Pub L-814e 3 i.MX6 BSP Manual
| Pub L-814e 3 i.MX6 BSP Manual | |
|---|---|
| Document Title | PhyCORE_I.MX6 BSP Manual |
| Document Type | BSP Manual |
| Yocto Page | |
| Article Number | L-814e_3 |
| Status | Published |
| Release Date | 2017/06/22 |
| Is Branch of | Yocto/i.MX6 BSP Manual Head |
| Compatible BSP'S | BSP Release Type | BSP Release Date | BSP Status |
|---|---|---|---|
| BSP-Yocto-i.MX6-PD16.1.0 | Final Release (stable final Release) | 23 January 2017 | Released |
| BSP-Yocto-i.MX6-PD16.1.1 | Fix Release | 7 February 2018 | Released |
| |
Contents
- 1 Introduction to Yocto
- 2 Introduction to the BSP
- 3 Building the BSP
- 4 Booting the System
- 5 Updating the Software
- 6 Device Tree (DT)
- 7 Accessing Peripherals
- 7.1 i.MX 6 Pin Muxing
- 7.2 Serial TTYs
- 7.3 Network
- 7.4 CAN Bus
- 7.5 MMC/SD Card
- 7.6 eMMC Devices
- 7.7 NAND Flash
- 7.8 GPIOs
- 7.9 SPI Master
- 7.10 I²C Bus
- 7.11 USB Host Controller
- 7.12 USB OTG
- 7.13 SATA
- 7.14 PCIe
- 7.15 Audio
- 7.16 Video
- 7.17 Framebuffer
- 7.18 CPU Core Frequency Scaling
- 7.19 CPU Core Management
- 7.20 Watchdog
- 7.21 Thermal Management
- 7.22 On-Chip OTP Controller (OCOTP_CTRL) - eFuses
- 7.23 WLAN Modules
- 8 Customizing the BSP
Introduction to Yocto
Please read the Yocto Reference Manual (L-813e_5) for a better understanding of Yocto and this BSP.
Introduction to the BSP
Supported Hardware
For information which boards and modules are supported by the release of PHYTEC’s i.MX 6 unified BSP described herein, visit our web page at http://www.phytec.de/produkte/software/yocto/phytec-unified-yocto-bsp-releases/.
Click the corresponding BSP release and look for the ordering number of your module in the column "Hardware Article Number". Now you can find the correct machine name in the corresponding cell under "Machine Name". (BSP-Yocto_Machines)
Building the BSP
This section will guide you through the general build process of the unified i.MX 6 BSP using the phyLinux script. If you want to use our software without phyLinux and the Repo tool managed environment instead, you can find all Git repositories on
git://git.phytec.de
Used barebox repository:
git://git.phytec.de/barebox
Our barebox version is based on the barebox mainline and adds only a few patches which will be sent upstream in future.
Used Linux kernel repository:
git://git.phytec.de/linux-mainline
Our i.MX 6 kernel is based on the Linux stable kernel. The stable kernel repository can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
To find out which tag is used for a specific board, have a look at your checked out BSP source folder under:
meta-phytec/recipes-bsp/barebox/barebox_*.bb meta-phytec/recipes-kernel/linux/linux-mainline_*.bb
Get the BSP
- Create a fresh project directory, e.g.
host$ mkdir ~/yocto
- Download and run the phyLinux script
host$ cd ~/yocto host$ wget ftp://ftp.phytec.de/pub/Software/Linux/Yocto/Tools/phyLinux host$ chmod +x phyLinux host$ ./phyLinux init
Basic Set-Up
There are a few important steps which have to be done, before the main build process.
- Setting up the host, see Yocto Reference Manual, "Setting up the Host"
- Setting up the Git configuration, see Yocto Reference Manual "Git Configuration"
Finding the right Software Platform
The i.MX 6 BSP is a unified BSP, which means it supports a set of different PHYTEC carrier boards (CB) with different Systems on Module (SOMs). Sometimes it is not easy to find the right software for your PHYTEC board. So if you need to figure out the corresponding machine name of your board, have a look at http://www.phytec.de/produkte/software/yocto/phytec-unified-yocto-bsp-releases/ and click on the corresponding BSP release, or refer to the files in the source folder of the BSP:
meta-phytec/conf/machine/*.conf
where you can find the platform name to the corresponding product IDs. All this information is also displayed by the phyLinux script.
E.g.: phyflex-imx6-2.conf machine configuration file:
#@TYPE: Machine #@NAME: phyflex-imx6-2 #@DESCRIPTION: PFL-A-02-13237E0.A1/PBA-B-01 (i.MX6 Quad, 1GB RAM on one bank, 16MB NOR)
Machine phyflex-imx6-2.conf represents the PBA-B-01 (Kit) CB with the PFL-A-02-13237E0.A1 SOM.
Selecting a Software Platform
- To select the correct SoC, BSP version and platform call:
host$ ./phyLinux init
It is also possible to pass this information directly using command line parameters:
host$ ./phyLinux init -p imx6 -r PD16.1.0
Please read section " Initialization" in the Yocto Reference Manual for more information.
Starting the Build Process
Refer to Yocto Reference Manual "Start the Build".
BSP Images
All images generated by Bitbake are deployed to yocto/build/deploy/images/<machine>.
The following list shows for example all files generated for the i.MX 6 SoC, phyflex-imx6-2 machine:
- Barebox: barebox.bin
- Barebox configuration: barebox.config
- Kernel: zImage
- Kernel device tree file: zImage-imx6q-phytec-pbab01.dtb
- Kernel configuration: zImage.config
- Root filesystem: phytec-qt5demo-image-phyflex-imx6-2.tar.gz, phytec-qt5demo-image-phyflex-imx6-2.ubifs, phytec-qt5demo-image-phyflex-imx6-2.ext4
- SD card image: phytec-qt5demo-image-phyflex-imx6-2.sdcard
Booting the System
The default boot source for the i.MX 6 modules like phyCORE-i.MX 6, phyFLEX‑i.MX 6 and phyCARD‑i.MX 6 is the NAND Flash. The easiest way to get started with your freshly created images is writing them to an SD card and setting the boot configuration accordingly. For information how to set the correct boot configuration, refer to the corresponding hardware manual for your PHYTEC board. (LAN-095e.A0 i.MX 6 Bootjumper Configurations).
Booting from NAND Flash
NAND is the default boot source. To update the software of the NAND Flash see "Updating the Software".
Booting from SD Card
Booting from SD card is useful in several situations, e.g. if the board does not start anymore due to a damaged bootloader. To boot from SD card the SD card must be formatted in a special way as the i.MX 6 does not use file systems. Instead, it is hard coded at which sectors of the SD card the i.MX 6 expects the bootloader.
There are two ways to create a bootable SD card. You can either use:
- a single prebuild SD card image, or
- the four individual images (barebox-, kernel- and device tree image, and root filesystem)
Using a single, prebuild SD Card Image
The first possibility is to use the SD card image built by Bitbake, a tool integrated in Yocto. This image has the ending *.sdcard and can be found under build/deploy/images/<MACHINE>/<IMAGENAME>-<MACHINE>.sdcard. It contains all BSP files in already correctly formatted partitions and can be copied to the SD card easily using the single Linux command dd.
You can also find ready-to-use *.sdcard images on our FTP server.
 |
To create your bootable SD card with the dd command you must have root privileges. Because of that, you must be very careful when selecting the destination device for the dd command! All files on the selected destination device will be erased immediately without any further query! Consequently, having selected the wrong device can also erase your hard drive! |
To create your bootable SD card you must first find out the correct device name of your SD card and possible partitions and then unmount the partitions before you start copying the image to the SD card.
- In order to get the correct device name first remove your SD card and execute ls /dev.
- Now insert your SD card and execute ls /dev again.
- Compare the two outputs to find the new device name(s) listed in the second output. These are the device names of the SD card (device, and partitions if the SD card is formatted).
- In order to verify the device names found, execute the command dmesg. Within the last lines of its output, you should also find the device names, for example sde (depending on your system).
Now that you have the device name /dev/<your_device> (e.g. /dev/sde) you can recognize the partitions which must be unmounted if the SD card is formatted, too. In this case you will also find /dev/<your_device> with an appended number (e.g. /dev/sde1) in the output. These represent the partition(s) to be unmounted.
- Unmount all partitions with:
host$ umount /dev/<your_device><number>
- After having unmounted all devices with an appended number (<your_device><number>), you can create your bootable SD card with
host$ sudo dd if=<IMAGENAME>-<MACHINE>.sdcard of=/dev/<your_device> bs=1MB conv=fsync
using the device name (<your_device>) without appended number (e.g. sde) which stands for the whole device.
The parameter conv=fsync forces a sync operation on the device before dd returns. This ensures that all blocks are written to the SD card and are not still in memory.
Using four individual Images (barebox-, kernel- and device tree image, and root filesystem)
Instead of using the single prebuild SD card image, you can also use the barebox-, kernel- and device tree image together with the root filesystem separately to create a bootable SD card manually.
For this method, a new card must be set up with 2 partitions and 8 MB of free space at the beginning of the card. Use the following procedure with fdisk under Linux:
- Create a new FAT partition with partition id C. When creating the new partition you must leave 8 MB of free space at the beginning of the card. When you go through the process of creating a new partition, fdisk lets you specify where the first sector starts. During this process fdisk will tell you where the first sector on the disk begins. If, for example, the first sector begins at 1000, and each sector is 512 bytes, then 8 MB / 512 bytes = 16384 sectors, thus your first sector should begin at 17384 to leave 8 MB of free space. The size of the FAT partition needs only be big enough to hold the zImage which is only a few megabytes. To be safe we recommend a size of 64 MB.
- Create a new Linux partition with partition id 83. Make sure you start this partition after the last sector of partition 1! By default fdisk will try to use the first partition available on the disk, which in this example is 1000. However, this is our reserved space! You must use the remaining portion of the card for this partition.
- Write the new partition to the SD card and exit fdisk.
Example:
- Type:
host$ sudo fdisk -l /dev/sdc
You will receive:
Disk /dev/sdc: 4025 MB, 4025483264 bytes 4 heads, 32 sectors/track, 61424 cylinders, total 7862272 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x26edf128 Device Boot Start End Blocks Id System /dev/sdc1 8192 24575 8192 c W95 FAT32 (LBA) /dev/sdc2 24576 655359 315392 83 Linux
- Remove and reinsert the card. Otherwise, Linux will not recognize the new partitions created in the previous step.
- Create a file system on the partitions with (replace 'sde' with your device):
host$ sudo mkfs.vfat /dev/sde1 host$ sudo mkfs.ext4 -L "rootfs" /dev/sde2
Now, the images need to be copied to the SD card.
- Write the bootloader in front of the first partition (replace 'sde' with your device):
host$ sudo dd if=barebox.bin of=/dev/sde bs=512 skip=2 seek=2 conv=fsync
- Mount the first partition (vfat) and copy the linuximage and oftree file to it:
host$ sudo mount /dev/sd<X>1 /mnt
| |
Make sure that the images are named as mentioned before, as the bootloader expects them exactly like that. |
- In case you want to boot the whole Linux from SD card, also mount the ext4 partition.
- Then untar <IMAGENAME>-<MACHINE>.tar.gz rootfs image to it:
host$ sudo mount /dev/sd<X>2 /media host$ sudo tar zxf <IMAGENAME>-<MACHINE>.tar.gz -C /media/
- Do not forget to properly unmount the SD card with:
host$ sudo umount /media
Booting from USB OTG (Serial Downloader)
The i.MX 6 ROM code is capable of downloading a bootloader from the USB OTG interface ("Serial Downloader" in the i.MX 6 Reference Manual). This is useful for a last resort recovery of a broken bootloader, or for rapid barebox development.
First, you have to compile the program imx-usb-loader in the barebox source directory. You can use any current mainline barebox version and you have to.
- First load the default configuration with:
host$ make ARCH=arm imx_v7_defconfig
- In order to activate imx-usb-loader type
host$ make ARCH=arm menuconfig
and enable System Type --> i.MX specific settings --> compile imx-usb-loader
- Now, compile the imx-usb-loader:
host$ make ARCH=arm CROSS_COMPILE=<prefix of your arm cross toolchain> scripts/imx/
Now the tool is in scripts/imx/imx-usb-loader.
To load the bootloader to the module execute the following sequence.
- Connect your target to your host PC via USB OTG.
- Check the boot configuration of your board and ensure that the ROM code enters Serial Downloader mode (see the corresponding section in the Hardware Manual of your board). (LAN-095e.A0 i.MX 6 Bootjumper Configurations)
- As the boot configuration is not read during a soft reset, perform a power cycle.
- Finally execute the imx-usb-loader, e.g.
host$ sudo scripts/imx/imx-usb-loader images/barebox-phytec-pbab01-1gib-1bank.img
After that you should see the barebox boot messages on the serial console.
Booting from SPI NOR Flash
Most of the i.MX 6 modules (e.g. phyCORE-i.MX 6 and phyFLEX-i.MX 6) are optionally equipped with SPI NOR Flash. To boot from SPI Flash, select the correct boot mode as described in the hardware manual of your PHYTEC board. The SPI Flash is usually quite small so that only the bootloader, the Linux kernel and the device tree can be stored. The root filesystem is taken from NAND Flash by default. How to flash the SPI NOR is described in section "Updating the Software".
Booting the Kernel from Network
In this case, booting from network means to load the kernel over TFTP and the root filesystem over NFS. The bootloader itself must already be loaded from any other boot device available.
Development Host Preparations
On the development host, a TFTP server must be installed and configured. The following tools will be needed to boot the Kernel from Ethernet:
- a TFTP server and
- a tool for starting/stopping a service.
- For Ubuntu install:
host$ sudo apt-get install tftpd-hpa xinetd
After the installation of the packages, you have to configure the TFTP server.
Set up for the TFTP server:
- Edit /etc/xinetd.d/tftp.
service tftp { protocol = udp port = 69 socket_type = dgram wait = yes user = root server = /usr/sbin/in.tftpd server_args = -s /tftpboot disable = no }
- Create a directory to store the TFTP files:
host$ sudo mkdir /tftpboot host$ sudo chmod -R 777 /tftpboot host$ sudo chown -R nobody /tftpboot
- Configure a static IP address for the appropriate interface:
host$ ifconfig eth1
You will receive:
eth1 Link encap:Ethernet HWaddr 00:11:6b:98:e3:47
inet addr:192.168.3.10 Bcast:192.168.3.255 Mask:255.255.255.0
- Restart the services to pick up the configuration changes:
host$ sudo service tftpd-hpa restart
- Now connect the first port of the board to your host system, configure the board to network boot and start it.
Usually, TFTP servers are using the /tftpboot directory to fetch files from. If you built your own images, please copy them from the BSP’s build directory to there.
We also need a network connection between the embedded board and the TFTP server. The server should be set to IP 192.168.3.10 and netmask 255.255.255.0.
After the installation of the TFTP server, an NFS server needs to be installed, too. The NFS server is not restricted to a certain file system location, so all we have to do on most distributions is to modify the file /etc/exports and export our root filesystem to the embedded network. In this example file, the whole work directory is exported, and the ”lab network” address of the development host is 192.168.3.10, so the IP addresses have to be adapted to the local needs:
/home/<user>/<rootfspath> 192.168.3.10/255.255.255.0(rw,no_root_squash,sync,no_subtree_check)
Where <user> must be replaced with your home directory name. The <rootfspath> can be set to a folder which contains a rootfs tar.gz image extracted with sudo.
Preparations on the Embedded Board
- To find out the Ethernet settings in the bootloader of the target type:
bootloader$ ifup eth0 bootloader$ devinfo eth0
With your development host set to IP 192.168.3.10 and netmask 255.255.255.0, the target should return:
ipaddr=192.168.3.11 netmask=255.255.255.0 gateway=192.168.3.10 serverip=192.168.3.10
- If you need to change something, type
bootloader$ edit /env/network/eth0
Here you can also change the IP address to DHCP instead of using a static one.
- Just configure:
ip=dhcp
- Edit the settings if necessary and save them by leaving the editor with CTRL+D.
- Type saveenv if you made any changes.
- Set up paths for TFTP and NFS in the file /env/boot/net.
Please note that these modifications will only affect the bootloader settings. For modifying the IP setting in Linux please refer to chapter Network.
Booting the Embedded Board
- To boot from network call
bootloader$ boot net
or restart the board and press m to stop autoboot. You will get a menu:
Main menu 1: Boot default 2: Detect bootsources 3: Settings 4: Save environment 5: Shell 6: Reset
- Press 2 and then Enter which opens a second menu:
boot 1: mmc 2: nand 3: spi 4: net 5: back
- Press 4 and then Enter in order to boot the board from network.
Custom Boot Setup
You may have custom boot requirements that are not covered by the four available boot files (nand, net, mmc, spi). If this is the case you can create your own custom boot entry specifying the kernel and root filesystem location.
- First create your own boot entry in barebox, for example named "custom":
bootloader$ edit /env/boot/custom
- Use the following template to specify the location of the Linux kernel and root filesystem.
#!/bin/sh global.bootm.image="<kernel_loc_bootm.image>" global.bootm.oftree="<dts_loc_bootm.oftree>" nfsroot="<nfs_root_path>" bootargs-ip /env/config-expansions global.linux.bootargs.dyn.root="<rootfs_loc_dyn.root>"
Please note that the text in <> such as <kernel_loc_bootm.image>, <rootfs_loc_dyn.root>, and <nfs_root_path> are intended to be replaced with user specific values as described in the following.
- <kernel_loc_bootm.image> specifies the location of the Linux kernel image and can be:
/dev/nand0.kernel.bb - To boot the Linux kernel from NAND /mnt/tftp/zImage - To boot the Linux kernel via TFTP /mnt/mmc/zImage - To boot the Linux kernel from SD/MMC card
- <dts_loc_bootm.oftree> specifies the location of the device tree binary and can be:
/dev/nand0.oftree.bb - To boot the device tree binary from NAND /mnt/tftp/oftree - To boot the device tree binary via TFTP /mnt/mmc/oftree - To boot the device tree binary from SD/MMC card
- <rootfs_loc_dyn.root> specifies the location of the root filesystem and can be:
root=ubi0:root ubi.mtd=root rootfstype=ubifs - To mount the root filesystem from NAND root=/dev/nfs nfsroot=$nfsroot,vers=3,udp rw consoleblank=0 - To mount the root filesystem via NFS root=/dev/mmcblk0p2 rootwait - To mount the root filesystem from SD/MMC card
- <nfs_root_path> is only required if mounting the root filesystem from NFS is desired. Replace with the following:
nfsroot="/home/${global.user}/nfsroot/${global.hostname}"
- After completing the modifications exit the editor using CTRL+D and save the environment:
bootloader$ saveenv
- To run your custom boot entry from the barebox shell enter:
bootloader$ boot custom
If you want to configure the bootloader for booting always from "custom", you need to create the /env/nv/boot.default file. Here you can just insert "custom" and save it. Otherwise, the boot source and boot order are defined in /env/init/bootsource.
Updating the Software
In this chapter, we explain how to use the barebox bootloader to update the images in NAND and SPI NOR Flash.
Updating from Network
i.MX 6 boards that have an Ethernet connector can be updated over a network. Be sure to set up the development host correctly. The IP needs to be set to 192.168.3.10, the netmask to 255.255.255.0, and a TFTP server needs to be available.
- Boot the system using any boot device available.
- Press any key to stop autoboot, then type:
bootloader$ ifup eth0 bootloader$ devinfo eth0
The Ethernet interfaces should be configured like this:
ipaddr=192.168.3.11 netmask=255.255.255.0 gateway=192.168.3.10 serverip=192.168.3.10
If a DHCP server is available, it is also possible to set:
ip=dhcp
If you need to change something:
- Type:
bootloader$ edit /env/network/eth0
- Edit the settings, save them by leaving the editor with CTRL+D and type:
bootloader$ saveenv
- Reboot the board.
Updating NAND Flash from Network
To update the bootloader you may use the barebox_update command. This provides a handler which automatically erases and flashes two copies of the barebox image into the NAND Flash. This makes the system more robust against ECC issues. If one block is corrupted the ROM loader does use the next block. This handler also creates an FCB table in the NAND. The FCB table is needed from the ROM loader to boot from NAND.
- Type:
bootloader$ barebox_update -t nand /mnt/tftp/barebox.bin
On startup the TFTP server is automatically mounted to /mnt/tftp. So copying an image from TFTP to flash can be done in one step. Do not get confused when doing an ls on the /mnt/tftp folder. The TFTP protocol does not support anything like ls so the folder will appear to be empty.
We recommend to also erase the environment of the old barebox. Otherwise the new barebox would use the old environment.
- First erase the old environment with:
bootloader$ erase /dev/nand0.barebox-environment.bb
After erasing the environment, you have to reset your board. Otherwise the barebox still uses the old environment.
- To reset your board in order to get the new barebox running type:
bootloader$ reset
- Create UBI volumes for Linux kernel, oftree and root filesystem in NAND:
bootloader$ ubiformat /dev/nand0.root bootloader$ ubiattach /dev/nand0.root bootloader$ ubimkvol -t static /dev/nand0.root.ubi kernel 8M bootloader$ ubimkvol -t static /dev/nand0.root.ubi oftree 1M bootloader$ ubimkvol -t dynamic /dev/nand0.root.ubi root 0
- Now get the Linux kernel and oftree from your TFTP server and store it also into the NAND Flash with:
bootloader$ ubiupdatevol /dev/nand0.root.ubi.kernel /mnt/tftp/linuximage bootloader$ ubiupdatevol /dev/nand0.root.ubi.oftree /mnt/tftp/oftree
 |
If you get the following message /mnt/tftp/linuximage has unknown filesize, this is not supported you have to copy the linux kernel and the oftree before with cp. |
bootloader$ cp /mnt/tftp/linuximage . bootloader$ cp /mnt/tftp/oftree .
bootloader$ ubiupdatevol /dev/nand0.root.ubi.kernel linuximage bootloader$ ubiupdatevol /dev/nand0.root.ubi.oftree oftree
- For flashing Linux’s root filesystem into NAND, please use:
bootloader$ cp -v /mnt/tftp/root.ubifs /dev/nand0.root.ubi.root
Updating SPI NOR Flash from Network
- To update the bootloader in the SPI NOR Flash from network do the following:
bootloader$ erase /dev/m25p0.barebox bootloader$ cp /mnt/tftp/barebox.bin /dev/m25p0.barebox
We recommend to also erase the environment of the old barebox. Otherwise the new barebox would use the old environment.
- First erase the old environment with:
bootloader$ erase /dev/m25p0.barebox-environment
After erasing the environment, you have to reset your board. Otherwise the barebox still uses the old environment.
- To reset your board in order to get the new barebox running type:
bootloader$ reset
- The kernel and oftree are then updated with the regular erase and cp commands:
bootloader$ erase /dev/m25p0.kernel bootloader$ cp /mnt/tftp/zImage /dev/m25p0.kernel bootloader$ erase /dev/m25p0.oftree bootloader$ cp /mnt/tftp/oftree /dev/m25p0.oftree
Finally, the root filesystem must be updated. As the root filesystem is too big to fit into the SPI NOR Flash the default configuration when booting from SPI is to take the root filesystem from NAND Flash. Thus, the following steps describe how to flash the root filesystem to the NAND Flash.
- For flashing Linux’s root filesystem into NAND, use:
bootloader$ ubiformat /dev/nand0.root bootloader$ ubiattach /dev/nand0.root bootloader$ ubimkvol /dev/nand0.root.ubi root 0 bootloader$ cp -v /mnt/tftp/root.ubifs /dev/nand0.root.ubi.root
Updating eMMC from Network
From a high-level point of view, an eMMC device is like an SD card. Therefore it is possible to flash the image <name>.sdcard from the Yocto build system directly to the eMMC. The image contains the bootloader, kernel, device trees and root filesystem.
- To flash the SD card image, use:
bootloader$ detect mmc3 bootloader$ cp -v /mnt/tftp/<name>.sdcard /dev/mmc3
| |
After flashing the SD card image the root filesystem does not use all available space on the device. To enlarge the file system see section "Resize the ext4 Root Filesystem". |
- If you only want to update the bootloader on the eMMC, use:
bootloader$ barebox_update -l bootloader$ barebox_update -t mmc3 /mnt/tftp/barebox.bin
to find the correct update target.
We recommend to also erase the environment of the old barebox. Otherwise the new barebox would use the old environment.
- Type:
bootloader$ cp /dev/zero /dev/mmc3.barebox-environment
- You should check the boot configuration of the eMMC device with:
bootloader$ detect mmc3 bootloader$ devinfo mmc3
If you used the cp command as described in the previous step the value of boot should be disabled, or user:
[...]
Parameters:
boot: disabled ("disabled", "boot0", "boot1", "user")
probe: 0
If the values are not disabled, or user the i.MX 6 ROM code cannot load the bootloader from the i.MX 6 device.
Now you have to reset your board. Otherwise the barebox still uses the old environment.
- To reset your board in order to get the new barebox running type:
bootloader$ reset
- To update the kernel and device tree, use:
bootloader$ ls /mnt/emmc bootloader$ cp /mnt/tftp/zImage /mnt/emmc/ bootloader$ cp /mnt/tftp/oftree /mnt/emmc/
Updating from SD Card
To update an i.MX 6 board from SD card the SD card used for updating must be mounted after the board is powered and the boot sequence is stopped on the bootloader prompt. If the board is booted from SD card the card is already mounted automatically under /mnt/mmc/.
The kernel and device tree are already in the first partition of the SD card to allow booting from the SD card. In order to use the SD card also for updating the barebox in the NAND, or NOR Flash, you have to copy the barebox.bin to the SD card on your host PC, too.
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|
The actual bootloader on the SD card is not in a partition. It is located before the first partition after the partition table. |
|---|---|
| You cannot update the root filesystem, because the first partition is too small for it. |
Updating NAND Flash from SD Card
To update the images on the NAND Flash from SD card basically the same commands as updating from TFTP are used with just the path parameters adapted.
- Type:
bootloader$ barebox_update -t nand /mnt/mmc/barebox.bin
We recommend to also erase the environment of the old barebox. Otherwise, the new barebox would use the old environment.
- First erase the old environment with:
bootloader$ erase /dev/nand0.barebox-environment.bb
After erasing the environment, you have to reset your board. Otherwise the barebox still uses the old environment.
- To reset your board in order to get the new barebox running type:
bootloader$ reset
- Create UBI volumes for Linux kernel, oftree and root filesystem in NAND:
bootloader$ ubiformat /dev/nand0.root bootloader$ ubiattach /dev/nand0.root
bootloader$ ubimkvol -t static /dev/nand0.root.ubi kernel 8M bootloader$ ubimkvol -t static /dev/nand0.root.ubi oftree 1M bootloader$ ubimkvol -t dynamic /dev/nand0.root.ubi root 0
- Now get the Linux kernel and oftree from your SD card and store it also into the NAND Flash with:
bootloader$ ubiupdatevol /dev/nand0.root.ubi.kernel /mnt/mmc/zImage bootloader$ ubiupdatevol /dev/nand0.root.ubi.oftree /mnt/mmc/oftree
For flashing Linux’s root filesystem to NAND, please use:
bootloader$ cp -v /mnt/tftp/rootfs.ubifs /dev/nand0.root.ubi.root
- Change the boot configuration of your board to NAND boot if necessary, and reset your board.
Updating SPI Flash from SD Card
To update the images on the SPI Flash from SD card basically the same commands as updating from TFTP are used with just the path parameters adapted.
- Type:
bootloader$ erase /dev/m25p0.barebox bootloader$ cp /mnt/mmc/barebox.bin /dev/m25p0.barebox
We recommend to also erase the environment of the old barebox. Otherwise the new barebox would use the old environment.
- First erase the old environment with:
bootloader$ erase /dev/m25p0.barebox-environment
After erasing the environment, you have to reset your board. Otherwise the barebox still uses the old environment.
- To reset your board in order to get the new barebox running type:
bootloader$ reset
- The kernel and oftree are then updated with the regular erase and cp commands:
bootloader$ erase /dev/m25p0.kernel bootloader$ cp /mnt/mmc/zImage /dev/m25p0.kernel
bootloader$ erase /dev/m25p0.oftree bootloader$ cp /mnt/mmc/oftree /dev/m25p0.oftree
- Change the boot configuration of your board to NOR boot if necessary, and reset your board.
Troubleshooting NAND Flash Update
Updating from BSP-Yocto-i.MX6-PD15.x.x or BSP-Yocto-i.MX6-PD16.1.x
In the BSP-Yocto-i.MX6-PD16.1.x the NAND Flash's partition layout has changed. Instead of having a separate Linux image and oftree partition the images are now part of the root UBIFS. Inside the root UBIFS, two new static volumes are being created. So the kernel and oftree are now kept more secure and protected with wear leveling by ubi. To update the BSP use one of the following two ways:
- Boot the new BSP from a different bootsource than NAND and follow the update instructions in the previous sections.
- Update the BSP using an older release. Update the barebox with the barebox_update command and delete the environment partition as described in the update sections above. Reboot the board from NAND. Continue with updating the kernel, device tree and root filesystem as described in the previous sections.
- Depending on the previous release, you might need to add -y to the ubiformat command, as the volume layout has changed.
Device Tree (DT)
Introduction
The following text describes briefly the Device Tree and can be found in the Linux kernel (linux/Documentation/devicetree/usage-model.txt).
"The "Open Firmware Device Tree", or simply Device Tree (DT), is a data structure and language for describing hardware. More specifically, it is a description of hardware that is readable by an operating system so that the operating system doesn't need to hard code details of the machine.
Structurally, the DT is a tree, or acyclic graph with named nodes, and nodes may have an arbitrary number of named properties encapsulating arbitrary data. A mechanism also exists to create arbitrary links from one node to another outside of the natural tree structure.
Conceptually, a common set of usage conventions called 'bindings', is defined for how data should appear in the tree to describe typical hardware characteristics including data busses, interrupt lines, GPIO connections, and peripheral devices."
The kernel is a really good source for a DT introduction. An overview of the device tree data format can be found on the device tree usage page at devicetree.org:
http://devicetree.org/Device_Tree_Usage
PHYTEC i.MX 6 BSP Device Tree Concept
The following sections explain some rules we have defined on how to set up device trees in first place for our i.MX 6 SoC based boards.
The device tree files are divided roughly into three layers:
- the SoC layer,
- the module layer, and
- the baseboard layer
This resembles the physical properties of the hardware. E.g., the same phyFLEX-i.MX 6 module can be used on the phyFLEX Carrier Board, the phyBOARD-Alcor i.MX 6 and the phyBOARD-Subra i.MX 6.
In each layer are multiple device tree include files.
Furthermore, common functionality within a layer is factored out into an extra device tree include file. E.g., module settings which are identical for Solo/DualLite and Dual/Quad controllers are placed into file imx6qdl-phytec-pfla02.dtsi. This file is included together with the specific Solo/DualLite module file imx6dl-phytec-pfla02.dtsi and the module file imx6q-phytec-pfla02.dtsi specific to the Dual/Quad controller.
An overview of the device tree hierarchy for all PHYTEC i.MX 6 platforms is presented in the figures below.
There are some special device tree files which do not fit into the layer scheme. The imx6qdl-phytec-lcd-018.dtsi is an example. It does not belong to a baseboard nor to a module. It contains the configuration of a display and a backlight which can be connected to a phyFLEX, or phyCARD Carrier Board.
Switching Expansion Boards and Displays
Disconnect all power before connecting an expansion board. After you plugged in the board, the software support can be activated in the bootloader without recompiling and flashing the images.
Here is a simple example on how to enable the imx6qdl-phytec-lcd-018-peb-av-02 (Display Expansion Board) on the phyBOARD-Mira using the barebox bootloader.
The configuration for any expansion board currently selected can be found in env/config-expansions. E.g.:
#!/bin/sh . /env/expansions/imx6qdl-phytec-lcd-018-peb-av-02
To enable an expansion board the file config-expansions in the barebox environment must be edited.
- To enable imx6qdl-phytec-lcd-018-peb-av-02, modify the env/config-expansions file and add, or uncomment the text according to the expansion board used. E.g. for the PEB-AV-02 on the phyBOARD-Mira:
#!/bin/sh . /env/expansions/imx6qdl-phytec-lcd-018-peb-av-02
config-expansions is called within each bootsource script (/env/boot/*) and will be executed before every boot process. This will cause the barebox to modify the DT used before the boot process. Information on which DT nodes are necessary for the expansion board can be found in the expansion configuration files.
imx6qdl-phytec-lcd-018-peb-av-02:
of_fixup_status /display@di0 of_fixup_status /backlight of_fixup_status /soc/aips-bus@02100000/i2c@021a0000/edt-ft5x06@38 of_fixup_status /soc/aips-bus@02000000/pwm@02080000
of_fixup_status is a barebox command and will enable a given DT node.
| |
The phyBOARD-Mira has a LVDS display connector. To enable this display connector with a 10" display uncomment #. /env/expansions/imx6qdl-mira-enable-lvds in env/config-expansions |
Handle the Different Displays
If you have chosen a display as expansion you have to select the appropriate display timings in the device tree.
- Append the following lines to the end of config-expansions, e.g. phyFLEX-i.MX6:
# imx6qdl-phytec-lcd: 7" display #of_display_timings -S /soc/aips-bus@02000000/ldb@020e0008/lvds-channel@0/display-timings/ETM0700G0DH6 # imx6qdl-phytec-lcd: 5.7" display #of_display_timings -S /soc/aips-bus@02000000/ldb@020e0008/lvds-channel@0/display-timings/ETMV570G2DHU # imx6qdl-phytec-lcd: 4.3" display #of_display_timings -S /soc/aips-bus@02000000/ldb@020e0008/lvds-channel@0/display-timings/ETM0430G0DH6 # imx6qdl-phytec-lcd: 3.5" display #of_display_timings -S /soc/aips-bus@02000000/ldb@020e0008/lvds-channel@0/display-timings/ETM0350G0DH6
- Uncomment the of_display_timings -S ... command for your screen size and save the file and environment.
Beside the display timings, you have to choose the right touchscreen type. Capacitive touchscreens are the standard touchscreens used with our boards. Thus, if you want to use a resistive touchscreen, you have to choose a modified board file in the env/config-expansions. The board files for resistive touchscreens all have the suffix -res.
Example: If you have the imx6qdl-phytec-lcd board, change the env/config-expansions from:
#!/bin/sh . /env/expansions/imx6qdl-phytec-lcd
to:
#!/bin/sh #. /env/expansions/imx6qdl-phytec-lcd-res
Bootloader's DT Modifications
The bootloader loads the device tree blob, a separate binary which includes the hardware description (section "Accessing Peripherals"). Then it will modify the loaded memory node at runtime. Thus, there is no need to handle different RAM sizes in the device tree. However, we added a memory node dummy without RAM size information. Because of that, a bootloader is needed which sets the memory node with the correct RAM size.
Snippet from imx6qdl-phytec-pfla02.dtsi:
memory { reg = <0x0 0x0>; /* will be filled by bootloader */ };
The memory node is not the only node, which is modified by the bootloader. Display nodes and nodes of expansion boards can be enabled, whereas the partition table in the kernel device tree is modified by the bootloader. Because of that, it is not possible to use our device trees without modifications with another bootloader, then the barebox bootloader from our unified BSP.
| |
The unified BSP contains device tree (DT) sources for the barebox bootloader and for the Linux kernel. The bootloader DT holds only the absolutely necessary hardware description for the basic board bring-up and is also using a different DT model. Make sure you are working with the right DT. |
- To get a sample barebox configuration type:
barebox$ cat env/boot/mmc
The output will show something like:
#!/bin/sh global.bootm.image="/mnt/mmc/zImage" # kernel image global.bootm.oftree="/mnt/mmc/oftree" # DTB
Accessing Peripherals
The following sections provide an overview of the supported hardware components and their corresponding operating system drivers. Further changes can be ported upon customer request.
To find out which boards and modules are supported by the release of PHYTEC’s i.MX 6 unified BSP described herein, visit our web page at http://www.phytec.de/produkte/software/yocto/phytec-unified-yocto-bsp-releases/ and click the corresponding BSP release. Now you can find all hardware supported in the columns "Hardware Article Number" and the correct machine name in the corresponding cell under "Machine Name". (BSP-Yocto_Machines)
To achieve maximum software re-use, the Linux kernel offers a sophisticated infrastructure, layering software components into board specific parts. The BSP tries to modularize the kit features as far as possible, which means that when a customized baseboard or even a customer-specific module is developed, most of the software support can be re-used without error-prone copy-and-paste. The kernel code corresponding to the boards can be found in device trees (DT) under linux/arch/arm/boot/dts/*.dts*
In fact, software re-use is one of the most important features of the Linux kernel and especially of the ARM implementation, which always had to fight with an insane number of possibilities of the System-on-Chip CPUs.
The whole board specific hardware is described in DTs and is not part of the kernel image itself. The hardware description is in its own separate binary, called Device Tree Blob (DTB) (section "Bootloader's DT Modifications").
Please read also section PHYTEC i.MX 6 BSP Device Tree Concept to get an understanding of our unified i.MX 6 BSP device tree model.
The following sections provide an overview of the supported hardware components and their operating system drivers on the i.MX 6 platform.
i.MX 6 Pin Muxing
The i.MX 6 SoC contains many peripheral interfaces. In order to reduce package size and lower overall system cost while maintaining maximum functionality, many of the i.MX 6 terminals can multiplex up to eight signal functions. Although there are many combinations of pin multiplexing that are possible, only a certain number of sets, called IO sets, are valid due to timing limitations. These valid IO sets were carefully chosen to provide many possible application scenarios for the user.
Please refer to the NXP i.MX 6 Reference Manuals for more information about the specific pins and the muxing capabilities:
- for the Solo and DualLite:
http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-processors/i.mx-6-processors/i.mx6qp/i.mx-6duallite-processors-dual-core-3d-graphics-hd-video-arm-cortex-a9-core:i.MX6DL?tab=Documentation_Tab&link_28
- for the Dual and Quad core:
http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-processors/i.mx-6-processors/i.mx6qp/i.mx-6quad-processors-high-performance-3d-graphics-hd-video-arm-cortex-a9-core:i.MX6Q?tab=Documentation_Tab&pspll_35
The IO set configuration, also called muxing, is done in the Device Tree. The driver pinctrl-single reads the DT's node "fsl,pins" and does the appropriate pin muxing.
The following is an example of the pin muxing of the UART4 device in imx6qdl-phytec-pfla02.dtsi:
pinctrl_uart4: uart4grp {
fsl,pins = <
MX6QDL_PAD_KEY_COL0__UART4_TX_DATA 0x1b0b1
MX6QDL_PAD_KEY_ROW0__UART4_RX_DATA 0x1b0b1
>;
};
The first part of the string MX6QDL_PAD_KEY_COL0__UART4_TX_DATA names the pad (e.g. PAD_KEY_COL0). The second part of the string (here UART4_TX_DATA) is the desired muxing option for this pad.
The pad setting value (hex value on the right) is explained in:
linux/Documentation/devicetree/bindings/pinctrl/fsl,imx6q-pinctrl.txt linux/Documentation/devicetree/bindings/pinctrl/fsl,imx6dl-pinctrl.txt
In this example the pad setting value 0x1b0b1 means the pin is configured with: PAD_CTL_HYS, PAD_CTL_SRE_SLOW, PAD_CTL_DSE_40ohm, PAD_CTL_SPEED_MED, PAD_CTL_PUS_100K_UP, PAD_CTL_PUE and PAD_CTL_PKE.
This example is defined in:
linux/arch/arm/boot/dts/imx6q-pinfunc.h
for the i.MX 6 Dual/Quad, and
linux/arch/arm/boot/dts/imx6dl-pinfunc.h
for the i.MX6 Solo/DualLite
Serial TTYs
The i.MX 6 SoC provides up to 5 so-called UART units. PHYTEC boards support different numbers of these UART units. The debug UART is configured as 115200 8N1 (115200 baud, 8 data bits, no parity bit, 1 stop bit). The other UARTs will come up with default settings, which normally will be 9600 baud.
PHYTEC i.MX 6 boards use different UART units as standard console output. The following table gives an overview of the UART units used for each i.MX 6 board available.
| Board | Standard Console Output |
|---|---|
| phyFLEX-i.MX6 | ttymxc3 |
| phyCARD-i.MX6 | ttymxc2 |
| phyBOARD-Alcor i.MX 6 | ttymxc3 |
| phyBOARD-Subra i.MX 6 | ttymxc3 |
| phyBOARD-Mira i.MX 6 | ttymxc1 |
- From the command line prompt of Linux user space you can easily check the availability of other UART interfaces with:
target$ echo "test" > /dev/ttymxc2
Be sure that the baudrate is set correctly on host and target side.
In order to get the currently configured baud rate, you can use the command stty on the target. The following example shows how to copy all serial settings from ttymxc3 (the standard console on most i.MX 6 boards) to ttymxc2.
- First get the current parameters with:
target$ stty -F /dev/ttymxc3 -g
5500:5:1cb2:a3b:3:1c:7f:15:4:0:1:0:11:13:1a:0:12:f:17:16:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0
- Now use the output from the stty command above as argument for the next command:
target$ stty -F /dev/ttymxc2 5500:5:1cb2:a3b:3:1c:7f:15:4:0:1:0:11:13:1a:0:12:f:17:16:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0
- You can also write both in just one command in order to make it more simple:
target$ stty -F /dev/ttymxc2 $(stty -g < /dev/ttymxc3)
Here is an example from imx6qdl-phytec-pfla02.dtsi:
&iomuxc { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_hog>; imx6q-phytec-pfla02 { pinctrl_uart3: uart3grp { fsl,pins = < MX6QDL_PAD_EIM_D24__UART3_TX_DATA 0x1b0b1 MX6QDL_PAD_EIM_D25__UART3_RX_DATA 0x1b0b1 MX6QDL_PAD_EIM_D30__UART3_RTS_B 0x1b0b1 MX6QDL_PAD_EIM_D31__UART3_CTS_B 0x1b0b1 >; }; pinctrl_uart4: uart4grp { fsl,pins = < MX6QDL_PAD_KEY_COL0__UART4_TX_DATA 0x1b0b1 MX6QDL_PAD_KEY_ROW0__UART4_RX_DATA 0x1b0b1 >; }; }; }; &uart3 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_uart3>; fsl,uart-has-rtscts; status = "disabled"; }; &uart4 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_uart4>; status = "disabled"; };
RS-485
The phyBOARD-MIRA can also provides on RS-485 interface derived from UART3. The following code snippet can be found in the imx6qdl-phytec-mira.dtsi and imx6q-phytec-mira-rdk-nand-rs485.dts:
imx6qdl-phytec-mira.dtsi:
&iomuxc { imx6qdl-phytec-phyboard-mira { pinctrl_uart3: uart3grp { fsl,pins = < MX6QDL_PAD_EIM_EB3__UART3_CTS_B 0x1b0b1 MX6QDL_PAD_EIM_D23__UART3_RTS_B 0x1b0b1 MX6QDL_PAD_EIM_D24__UART3_TX_DATA 0x1b0b1 MX6QDL_PAD_EIM_D25__UART3_RX_DATA 0x1b0b1 >; }; }; }; &uart3 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_uart3>; fsl,uart-has-rtscts; status = "disabled"; };
imx6q-phytec-mira-rdk-nand-rs485.dts:
&uart3 { linux,rs485-enabled-at-boot-time; rs485-rts-active-high; status = "okay"; };
For first easy testing, the RS-485 port must be configured.
- Execute:
target$ stty -F /dev/ttymxc2 -echo -echoe -echok -echoctl -echoke 115200
Now, you can "echo" and "cat" data to and from /dev/ttymxc2
Network
The Ethernet features provided by our modules and boards vary (e.g.: 1 x 10/100 Mbit, or 1 x 1 Gbit).
However, all interfaces offer a standard Linux network port which can be programmed using the BSD socket interface.
The whole network configuration is handled by the systemd-networkd daemon. The relevant configuration files can be found on the target in /lib/systemd/network/ and also in the BSP in meta-yogurt/recipes-core/systemd/systemd/.
IP addresses can be configured within *.network files. The default IP address and netmask for eth0 are:
eth0: 192.168.3.11/24
The DT Ethernet setup might be split into two files depending on your hardware configuration, the module DT, and the board specific DT.
Example phyCORE-i.MX 6 mounted on phyBOARD-Mira i.MX 6:
Module DT, arch/arm/boot/dts/imx6qdl-phytec-phycore-som.dtsi:
&fec { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_enet>; phy-handle = <ðphy>; phy-mode = "rgmii"; phy-supply = <&vdd_eth_io>; phy-reset-gpios = <&gpio1 14 GPIO_ACTIVE_LOW>; status = "disabled"; mdio { #address-cells = <1>; #size-cells = <0>; ethphy: ethernet-phy@3 { reg = <3>; txc-skew-ps = <1680>; rxc-skew-ps = <1860>; }; }; }; &iomuxc { imx6qdl-phytec-phycore-som { pinctrl_enet: enetgrp { fsl,pins = < MX6QDL_PAD_ENET_MDIO__ENET_MDIO 0x1b0b0 MX6QDL_PAD_ENET_MDC__ENET_MDC 0x1b0b0 MX6QDL_PAD_RGMII_TXC__RGMII_TXC 0x1b0b0 MX6QDL_PAD_RGMII_TD0__RGMII_TD0 0x1b0b0 MX6QDL_PAD_RGMII_TD1__RGMII_TD1 0x1b0b0 MX6QDL_PAD_RGMII_TD2__RGMII_TD2 0x1b0b0 MX6QDL_PAD_RGMII_TD3__RGMII_TD3 0x1b0b0 MX6QDL_PAD_RGMII_TX_CTL__RGMII_TX_CTL 0x1b0b0 MX6QDL_PAD_ENET_REF_CLK__ENET_TX_CLK 0x1b0b0 MX6QDL_PAD_RGMII_RXC__RGMII_RXC 0x1b0b0 MX6QDL_PAD_RGMII_RD0__RGMII_RD0 0x1b0b0 MX6QDL_PAD_RGMII_RD1__RGMII_RD1 0x1b0b0 MX6QDL_PAD_RGMII_RD2__RGMII_RD2 0x1b0b0 MX6QDL_PAD_RGMII_RD3__RGMII_RD3 0x1b0b0 MX6QDL_PAD_RGMII_RX_CTL__RGMII_RX_CTL 0x1b0b0 MX6QDL_PAD_ENET_TX_EN__ENET_TX_EN 0x1b0b0 MX6QDL_PAD_SD2_DAT1__GPIO1_IO14 0x80000000 >; }; }; };
Board specific DT, arch/arm/boot/dts/imx6dl-phytec-mira-rdk-nand.dts:
ðphy { max-speed = <100>; }; &fec { status = "okay"; };
CAN Bus
The phyFLEX-i.MX 6 provides a Controller Area Network (CAN) interface, which is supported by drivers using the proposed Linux standard CAN framework SocketCAN. Using this framework, CAN interfaces can be programmed with the BSD socket API.
The CAN bus offers a low-bandwidth, prioritized message fieldbus for serial communication between microcontrollers. Unfortunately, CAN was not designed with the ISO/OSI layer model in mind, so most CAN APIs available throughout the industry do not support a clean separation between the different logical protocol layers, as for example, known from Ethernet.
The SocketCAN framework for Linux extends the BSD socket API concept towards CAN bus. Because of that, using this framework, the CAN interfaces can be programmed with the BSD socket API and behaves like an ordinary Linux network device, with some additional features special to CAN.
- E.g., use:
target$ ip link
to see if the interface is up or down, but the given MAC and IP addresses are arbitrary and obsolete.
- To get the information on can0 (which represents i.MX 6’s CAN module FLEXCAN1) such as bit rate and error counters type:
target$ ip -d -s link show can0
The information for can0 will look like the following:
2: can0: <NOARP,ECHO> mtu 16 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 10 link/can promiscuity 0 can state STOPPED (berr-counter tx 0 rx 0) restart-ms 0 bitrate 10000 sample-point 0.866 tq 6666 prop-seg 6 phase-seg1 6 phase-seg2 2 sjw 1 flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1 clock 30000000 re-started bus-errors arbit-lost error-warn error-pass bus-off 0 0 0 0 0 0 RX: bytes packets errors dropped overrun mcast 0 0 0 0 0 0 TX: bytes packets errors dropped carrier collsns 0 0 0 0 0 0
The output contains a standard set of parameters also shown for Ethernet interfaces, so not all of these are necessarily relevant for CAN (for example the MAC address). The following output parameters contain useful information:
| Field | Description |
|---|---|
| can0 | Interface Name |
| NOARP | CAN cannot use ARP protocol |
| MTU | Maximum Transfer Unit |
| RX packets | Number of Received Packets |
| TX packets | Number of Transmitted Packets |
| RX bytes | Number of Received Bytes |
| TX bytes | Number of Transmitted Bytes |
| errors... | Bus Error Statistics |
The CAN configuration is done in the systemd configuration file /lib/systemd/system/can0.service.
For a persistent change of e.g. the default bitrates change the configuration in the BSP under ./meta-yogurt/recipes-core/systemd/systemd-machine-units/can0.service in the root filesystem instead and rebuild the root filesystem.
[Unit] Description=can0 interface setup [Service] Type=simple RemainAfterExit=yes ExecStart=/sbin/ip link set can0 up type can bitrate 500000 ExecStop=/sbin/ip link set can0 down [Install] WantedBy=basic.target
The can0.service is started after boot by default. You can start and stop it with:
target$ systemctl stop can0.service target$ systemctl start can0.service
You can send messages with cansend or receive messages with candump:
target$ cansend can0 123#45.67 target$ candump can0
To generate random CAN traffic for testing purpose use cangen.
target$ cangen
See cansend --help and candump --help help messages for further information on options and usage.
The corresponding kernel part can be found within the board specific DT, e.g. arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi
&can1 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_flexcan1>; status = "disabled"; }; &iomuxc { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_hog>; imx6q-phytec-pfla02 { pinctrl_flexcan1: flexcan1grp { fsl,pins = < MX6QDL_PAD_KEY_ROW2__FLEXCAN1_RX 0x1b0b0 MX6QDL_PAD_KEY_COL2__FLEXCAN1_TX 0x1b0b0 >; }; }; };
MMC/SD Card
All i.MX 6 kits support a slot for Secure Digital Cards and Multimedia Cards to be used as general purpose block devices. The phyFLEX-i.MX 6 supports even two slots for Secure Digital Cards and Multimedia Cards.
These devices can be used in the same way as any other block device.
| |
This kind of devices are hot pluggable. Nevertheless, you must pay attention not to unplug the device while it is still mounted. This may result in data loss. |
After inserting an MMC/SD card, the kernel will generate new device nodes in /dev. The full device can be reached via its /dev/mmcblk0 device node, MMC/SD card partitions will show up in the following way:
/dev/mmcblk0p<Y>
<Y> counts as the partition number starting from 1 to the max. count of partitions on this device.
The partitions can be formatted with any kind of file system and also handled in a standard manner, e.g. the mount and umount command work as expected.
|
|
These partition device nodes will only be available if the card contains a valid partition table (”hard disk” like handling). If it does not contain one, the whole device can be used as a file system (”floppy” like handling). In this case /dev/mmcblk0 must be used for formatting and mounting. |
|---|---|
| The cards are always mounted as being writable. Write-protection of MMC/SD cards is only recognized on the phyCARD and the phyFLEX Carrier Board. |
DT configuration for the MMC interface in arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi:
&iomuxc { imx6q-phytec-pfla02 { pinctrl_usdhc2: usdhc2grp { fsl,pins = < MX6QDL_PAD_SD2_CMD__SD2_CMD 0x170f9 MX6QDL_PAD_SD2_CLK__SD2_CLK 0x100f9 MX6QDL_PAD_SD2_DAT0__SD2_DATA0 0x170f9 MX6QDL_PAD_SD2_DAT1__SD2_DATA1 0x170f9 MX6QDL_PAD_SD2_DAT2__SD2_DATA2 0x170f9 MX6QDL_PAD_SD2_DAT3__SD2_DATA3 0x170f9 >; }; pinctrl_usdhc3: usdhc3grp { fsl,pins = < MX6QDL_PAD_SD3_CMD__SD3_CMD 0x17059 MX6QDL_PAD_SD3_CLK__SD3_CLK 0x10059 MX6QDL_PAD_SD3_DAT0__SD3_DATA0 0x17059 MX6QDL_PAD_SD3_DAT1__SD3_DATA1 0x17059 MX6QDL_PAD_SD3_DAT2__SD3_DATA2 0x17059 MX6QDL_PAD_SD3_DAT3__SD3_DATA3 0x17059 >; }; pinctrl_usdhc3_100mhz: usdhc3grp100mhz { fsl,pins = < MX6QDL_PAD_SD3_CMD__SD3_CMD 0x170b9 MX6QDL_PAD_SD3_CLK__SD3_CLK 0x100b9 MX6QDL_PAD_SD3_DAT0__SD3_DATA0 0x170b9 MX6QDL_PAD_SD3_DAT1__SD3_DATA1 0x170b9 MX6QDL_PAD_SD3_DAT2__SD3_DATA2 0x170b9 MX6QDL_PAD_SD3_DAT3__SD3_DATA3 0x170b9 >; }; pinctrl_usdhc3_200mhz: usdhc3grp200mhz { fsl,pins = < MX6QDL_PAD_SD3_CMD__SD3_CMD 0x170f9 MX6QDL_PAD_SD3_CLK__SD3_CLK 0x100f9 MX6QDL_PAD_SD3_DAT0__SD3_DATA0 0x170f9 MX6QDL_PAD_SD3_DAT1__SD3_DATA1 0x170f9 MX6QDL_PAD_SD3_DAT2__SD3_DATA2 0x170f9 MX6QDL_PAD_SD3_DAT3__SD3_DATA3 0x170f9 >; }; pinctrl_usdhc3_cdwp: usdhc3cdwp { fsl,pins = < MX6QDL_PAD_ENET_RXD0__GPIO1_IO27 0x80000000 MX6QDL_PAD_ENET_TXD1__GPIO1_IO29 0x80000000 >; }; }; }; &usdhc2 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_usdhc2>; cd-gpios = <&gpio1 4 0>; wp-gpios = <&gpio1 2 0>; status = "disabled"; }; &usdhc3 { pinctrl-names = "default", "state_100mhz", "state_200mhz"; pinctrl-0 = <&pinctrl_usdhc3 &pinctrl_usdhc3_cdwp>; pinctrl-1 = <&pinctrl_usdhc3_100mhz &pinctrl_usdhc3_cdwp>; pinctrl-2 = <&pinctrl_usdhc3_200mhz &pinctrl_usdhc3_cdwp>; cd-gpios = <&gpio1 27 0>; wp-gpios = <&gpio1 29 0>; no-1-8-v; vmmc-supply = <&vdd_sd0_reg>; status = "disabled"; };
eMMC Devices
PHYTEC modules, e.g. phyCORE-i.MX 6, can be populated with an eMMC memory chip as main storage instead of the NAND Flash. eMMC devices contain raw MLC memory cells (section "Enable pseudo-SLC Mode") combined with a memory controller, that handles ECC and wear leveling. They are connected via an MMC/SD interface to the i.MX 6 and are represented as block devices in the Linux kernel like SD cards, flash drives, or hard disks.
The electric and protocol specification is provided by JEDEC (https://www.jedec.org/standards-documents/technology-focus-areas/flash-memory-ssds-ufs-emmc/e-mmc). The eMMC manufacturer's datasheet is mostly relatively short and meant to be read together with the supported version of the JEDEC eMMC standard.
PHYTEC currently utilizes two eMMC chips:
| Module article number | eMMC chip | Size | JEDEC version |
|---|---|---|---|
| PCM-058-30242C0X.A0 | Micron MTFC4GMDEA-4M IT | 4 GB | MMC 4.41 |
| PCM-058-40233C0I.A0 | Micron MTFC8GLDEA-4M IT | 8 GB | MMC 4.41 |
Extended CSD Register
eMMC devices have an extensive amount of extra information and settings that is available via the Extended CSD registers. For a detailed list of the registers see manufacturer datasheets and the JEDEC standard.
- In the Linux user space you can query the registers with:
target$ mmc extcsd read /dev/mmcblk3
You will see:
============================================= Extended CSD rev 1.5 (MMC 4.41) ============================================= Card Supported Command sets [S_CMD_SET: 0x01] [...]
- In the bootloader you can use
bootloader$ detect mmc3
if the device is not probed yet, and then
bootloader$ mmc_extcsd /dev/mmc3
Enable Background Operations (BKOPS)
In contrast to raw NAND Flashs an eMMC device contains a Flash Transfer Layer (FTL) that handles the wear leveling, block management and ECC of the raw MLC cells. This requires some maintenance tasks, e.g. erasing non used blocks, that are performed regularly. These tasks are called Background Operations (BKOPS).
In the default case, which depends on the chip, the background operations are not executed periodically which impacts the worst-case read and write latency.
Therefore the JEDEC Standard version v4.41 specifies a method, that the host can issue BKOPS manually. See the JEDEC Standard chapter Background Operations and the description of registers BKOPS_EN (Reg: 163) and BKOPS_START (Reg: 164) in the eMMC datasheet for more details.
Meaning of Register BKOPS_EN (Reg: 163) Bit MANUAL_EN (Bit 0):
- Value 0: The host does not support manual trigger of BKOPS. Device write performance suffers.
- Value 1: The host does support manual trigger of BKOPS. It will issue BKOPS from time to time when it does not need the device.
The mechanism to issue background operations is already implemented in the Linux kernel since v3.7. You only have to enable BKOPS_EN on the eMMC device (see below for details).
The JEDEC standard v5.1 introduces a new automatic BKOPS feature. It frees the host to trigger the background operations regularly because the device starts BKOPS itself when it is idle (see description of bit AUTO_EN in register BKOPS_EN (Reg: 163)).
eMMC chips deployed by PHYTEC currently do not support the new standard v5.1. The Linux kernel and user space tool mmc do not support the feature either.
- To check whether BKOPS_EN is set, execute:
target$ mmc extcsd read /dev/mmcblk3 | grep BKOPS_EN
The output will be for example:
Enable background operations handshake [BKOPS_EN]: 0x01
Here BKOPS_EN is enabled. The host will issue background operations from time to time.
There is also a kernel boot message showing if BKOPS_EN is not set:
mmc1: MAN_BKOPS_EN bit is not set
- To set the BKOPS_EN bit execute:
target$ bkops enable /dev/mmcblk3
- To ensure that the new setting is taken over and the kernel triggers BKOPS by itself, shut down the system with:
target$ poweroff
and perform a power cycle.
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The BKOPS_EN bit is one-time-programmable only. It cannot be reversed. |
Enable pseudo-SLC Mode
eMMC devices use MLC memory cells (https://en.wikipedia.org/wiki/Multi-level_cell) to store the data. Compared with SLC memory cells used in NAND Flashs MLC memory cells have a lower reliability and a higher error rate at lower costs.
If you prefer reliability over storage capacity, you can enable the pseudo-SLC mode, or SLC mode. The method, used here, employs the enhanced attribute, describe in the JEDEC standard, which can be set for continuous regions of the device. The JEDEC standard does not specify the implementation details and the guarantees of the enhanced attribute. This is left to the chipmaker. For the Micron chips the enhanced attribute increases the reliability, but also halves the capacity.
| |
When enabling the enhanced attribute on the device all data will be lost. |
The following sequence shows how to enable the enhanced attribute.
- First obtain the current size of the eMMC device with:
target$ parted -m /dev/mmcblk3 unit B print
You will receive:
BYT; /dev/mmcblk3:3783262208B:sd/mmc:512:512:unknown:MMC MMC04G:;
As you can see this device has 3783262208 Byte = 3608.0 MiB.
- To get the maximum size of the device after pseudo-SLC is enabled use
target$ mmc extcsd read /dev/mmcblk3 | grep ENH_SIZE_MULT -A 1
which shows for example:
Max Enhanced Area Size [MAX_ENH_SIZE_MULT]: 0x0001c3 i.e. 1847296 KiB -- Enhanced User Data Area Size [ENH_SIZE_MULT]: 0x000000 i.e. 0 KiB
Here the maximum size is 1847296 KiB = 1804 MiB.
- Now, you can set enhanced attribute for the whole device, e.g. 1847296 KiB, by typing:
target$ mmc enh_area set -y 0 1847296 /dev/mmcblk3
You will get:
Done setting ENH_USR area on /dev/mmcblk3 setting OTP PARTITION_SETTING_COMPLETED! Setting OTP PARTITION_SETTING_COMPLETED on /dev/mmcblk3 SUCCESS Device power cycle needed for settings to take effect. Confirm that PARTITION_SETTING_COMPLETED bit is set using 'extcsd read' after power cycle
- To ensure that the new setting is taken over shut down the system with:
target$ poweroff
and perform a power cycle.
It is recommended to verify the settings, now.
- First check the value of ENH_SIZE_MULT which must be 1847296 KiB:
targe$ mmc extcsd read /dev/mmcblk3 | grep ENH_SIZE_MULT -A 1
You should receive:
Max Enhanced Area Size [MAX_ENH_SIZE_MULT]: 0x0001c3 i.e. 1847296 KiB -- Enhanced User Data Area Size [ENH_SIZE_MULT]: 0x0001c3 i.e. 1847296 KiB
- Finally check the size of the device, in this example it should be 1891631104 Byte = 1804.0 MiB with:
target$ parted -m /dev/mmcblk3 unit B print
BYT; /dev/mmcblk3:1891631104B:sd/mmc:512:512:unknown:MMC MMC04G:;
- Now you can flash your new image.
Further reference: https://www.micron.com/support/faqs/products/managed-nand/emmc (chapter "What are the enhanced technology features mentioned in JEDEC specification, and what are the benefits?")
eMMC (Boot-)Partitions
An eMMC device contains already four different hardware partitions: user, boot1, boot2 and rpmb.
The user partition is called the User Data Area in the JEDEC standard and is the main storage partition. The partitions boot1 and boot2 can be used to host the bootloader and are more reliable. Which partition the i.MX 6 uses to load the bootloader, is controlled by the boot configuration of the eMMC device. The partition rpmb is a small partition and can only be accessed via trusted mechanism.
Furthermore, the user partition can be divided into four user-defined General Purpose Area Partitions. An explanation of this feature exceeds the scope of this document. For further information see the JEDEC Standard chapter "7.2 Partition Management".
| |
Do not confuse eMMC partitions with partitions of a DOS MBR, or GPT partition table. |
The current PHYTEC BSP does not use the extra partitioning feature of eMMC devices. The barebox is flashed at the beginning of the user partition. The barebox environment is placed at a fix location after the barebox. An MBR partition table is used to create two partitions, a FAT32 boot and ext4 rootfs partition. They are located right after the barebox and the barebox environment. The FAT32 boot partition contains kernel and device tree.
There are two ways to flash the bootloader to one of the two boot partitions and to switch the boot device, either via bootloader, or via user space commands, as shown in the following examples.
1. Via bootloader:
- First detect the eMMC if not already done:
bootloader$ detect mmc3
- Now, query some information about the eMMC device:
bootloader$ devinfo mmc3
The output will look like this:
Host information:
[...]
Parameters:
boot: disabled ("disabled", "boot0", "boot1", "user")
nt_signature: 85f3edec
probe: 1
Here the boot partition is currently set to disabled.
- Next flash the bootloader to the partition boot0:
bootloader$ cp -v /mnt/tftp/barebox.bin /dev/mmc3.boot0
- Finally switch the boot partition to boot0:
bootloader$ mmc3.boot=boot0
2. Via user space commands:
The partitions boot0 and boot1 are read-only by default. To write to them from user space you have to disable force_ro in the sysfs.
- Type:
target$ echo 0 > /sys/block/mmcblk3boot0/force_ro
- Now, flash the bootloader to partition boot0:
target$ dd if=/tmp/barebox.bin of=/dev/mmcblk3boot0
- After that set the boot partition from user space using the mmc tool:
target$ mmc bootpart enable 1 0 /dev/mmcblk3
(for 'boot0')
target$ mmc bootpart enable 2 0 /dev/mmcblk3
(for 'boot1')
target$ mmc bootpart enable 7 0 /dev/mmcblk3
(for 'user')
Currently, the mmc tool does not provide a way to show the current boot partition configuration.
Reliable Write
There are two different Reliable Write options:
- Reliable Write option for a whole eMMC device/partition
- Reliable Write for single write transactions
| |
Do not confuse eMMC partitions with partitions of a DOS MBR, or GPT partition table (see previous section). |
The first Reliable Write option can be enable with the mmc tool:
target$ mmc --help
[...] mmc write_reliability set <-y|-n> <partition> <device>
The second Reliable Write option is the configuration bit Reliable Write Request parameter (bit 31) in command CMD23. It is already used in the kernel since v3.0 by file systems, e.g. ext4 for the journal, and user space applications such as fdisk for the partition table. In the Linux kernel source code it is handled via flag REQ_META.
Conclusion: ext4 file system with mount option data=journal should be safe against power cuts. The file system check can recover the file system after a power failure, but data that was written just before the power cut maybe lost. At least a consistent state of the file system can be recovered. To ensure data consistency for the files of an application, the system functions fdatasync, or fsync should be used in the application.
Resize the ext4 Root Filesystem
parted and resize2fs can be used to expand the root filesystem. The example works for any block device such as eMMC, SD card, or hard disk.
- Get the current device size:
target$ parted -m /dev/mmcblk0 unit B print
The output looks like:
BYT; /dev/mmcblk0:3991928832B:sd/mmc:512:512:msdos:SD USD:; 1:4194304B:12582911B:8388608B:::lba; 2:12582912B:138412031B:125829120B:ext4::;
- Now use the size of device minus one as the new end of the second partition (e.g. 3991928832B):
target$ parted /dev/mmcblk0 resizepart 2 3991928831B
- After expanding the partition size, resize the ext4 file system in the partition:
target$ resize2fs /dev/mmcblk0p2
The command's output looks like this:
resize2fs 1.42.9 (28-Dec-2013) Filesystem at /dev/mmcblk0p2 is mounted on /; on-line resizing required old_desc_blocks = 1, new_desc_blocks = 15 The filesystem on /dev/mmcblk0p2 is now 3886080 blocks long.
Increasing the file system size can be done while it is mounted. An on-line resizing operation is performed. But you can also boot the board from SD card and then resize the file system on the eMMC partition while it is not mounted.
Erase the Device
It is possible to erase the eMMC device directly rather than overwriting it with zeros. The eMMC block management algorithm will erase the underlying MLC memory cells or mark these blocks as discard. The data on the device is lost and will be read back as zeros.
- After booting from SD card execute:
target$ blkdiscard --secure /dev/mmcblk3
The option --secure ensures that the command waits until the eMMC device has erased all blocks.
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dd if=/dev/zero of=/dev/mmcblk3 also destroys all information on the device, but is bad for wear leveling and takes much longer! |
For raw NAND flashes, the same could be achieved with the command flash_erase.
Additional Software in the BSP
In the BSP you will also find the tool flashbench which allows to get the page size and erase block size.
- E.g. type:
target$ flashbench -a /dev/mmcblk3 --blocksize=1024
This will, for example, result in:
align 1073741824 pre 779µs on 1.21ms post 768µs diff 439µs align 536870912 pre 855µs on 1.29ms post 858µs diff 433µs align 268435456 pre 846µs on 1.29ms post 821µs diff 454µs align 134217728 pre 812µs on 1.25ms post 822µs diff 429µs align 67108864 pre 846µs on 1.29ms post 832µs diff 452µs align 33554432 pre 830µs on 1.24ms post 807µs diff 422µs align 16777216 pre 841µs on 1.26ms post 842µs diff 418µs align 8388608 pre 842µs on 1.27ms post 814µs diff 446µs align 4194304 pre 838µs on 1.28ms post 842µs diff 436µs align 2097152 pre 827µs on 928µs post 834µs diff 97.9µs align 1048576 pre 826µs on 921µs post 827µs diff 94.5µs align 524288 pre 828µs on 924µs post 841µs diff 89.6µs align 262144 pre 835µs on 903µs post 841µs diff 65.1µs align 131072 pre 842µs on 949µs post 853µs diff 101µs align 65536 pre 854µs on 959µs post 858µs diff 103µs align 32768 pre 844µs on 954µs post 869µs diff 97.2µs align 16384 pre 862µs on 962µs post 847µs diff 108µs align 8192 pre 849µs on 946µs post 847µs diff 98.5µs align 4096 pre 858µs on 953µs post 855µs diff 96.9µ2s align 2048 pre 845µs on 936µs post 846µs diff 90.8µs
For an explanation how to interpret the output see: https://git.linaro.org/people/arnd.bergmann/flashbench.git/blob/HEAD:/README#l1
NAND Flash
PHYTEC i.MX 6 modules are equipped with raw NAND memory, which is used as media for storing Linux, DTB and root filesystem, including applications and their data files.
The NAND Flash is connected to the General Purpose Media Interface (GPMI) of the i.MX 6. The NAND Flash type and size is automatically being detected via the Open NAND Flash Interface (ONFI) during boot.
This type of media is managed by the UBI file system. This file system uses compression and decompression on the fly to increase the quantity of data stored.
From Linux user space the NAND Flash partitions start with /dev/mtdblock0. Only the /dev/mtdblock4 on the PHYTEC modules has a file system, meaning that the other partitions cannot be mounted to the root filesystem. The only way to access them is by flashing a prepared flash image into the corresponding /dev/mtd device node.
The partitions of a NAND Flash are defined in all DTs, but the barebox bootloader overwrites only the partitions of the kernel device tree. Thus, changing the partitions has to be done either in the barebox DT, or in the barebox environment. How to modify the partitions during runtime in the barebox environment is described in section "Changing MTD Partitions". Adding new partitions can be done by creating a new partition node in the corresponding board device tree ("PHYTEC i.MX 6 BSP Device Tree Concept").
The property label defines the name of the partition and the reg value the offset and size of a partition. Do not forget to update all following partitions when adding a partition, or changing a partition's size.
The partitions are defined in the DT, e.g. imx6qdl-phytec-pfla02.dtsi in the barebox:
&gpmi { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_gpmi_nand>; nand-on-flash-bbt; status = "okay"; #address-cells = <1>; #size-cells = <1>; partition@0 { label = "barebox"; reg = <0x0 0x400000>; }; partition@1 { label = "barebox-environment"; reg = <0x400000 0x100000>; }; partition@2 { label = "oftree"; reg = <0x500000 0x100000>; }; partition@3 { label = "kernel"; reg = <0x600000 0x800000>; }; partition@4 { label = "root"; reg = <0xe00000 0x0>; }; };
We also kept the partition nodes in the Linux Kernel DT as a fallback.
GPIOs
PHYTEC boards have often a set of pins specially dedicated as user I/Os. Those pins are connected directly to i.MX 6 pins and are muxed as GPIOs. They are directly usable in Linux user space. The processor has organized its GPIOs into six banks (GPIO1 – GPIO6) of 32 GPIOs each and one bank with 14 GPIOs. gpiochip0, gpiochip32, gpiochip64, gpiochip96, gpiochip128, gpiochip160 and gpiochip192 are the sysfs representation of these internal i.MX 6 GPIO banks GPIO1 – GPIO7.
The GPIOs are identified as GPIO<X>_<Y> (e.g. GPIO5_07). <X> identifies the GPIO bank and counts from 1 to 7, while <Y> stands for the GPIO within the bank. <Y> is being counted from 0 to 31 (32 GPIOs on each bank).
By contrast, the Linux kernel uses a single integer to enumerate all available GPIOs in the system. The formula to calculate the right number is:
Linux GPIO number: <N> = (<X> - 1) * 32 + <Y>
Accessing GPIOs from user space will be done using the sysfs path /sys/class/gpio/.
- First you have to register the GPIO that you want to use by writing its numbers into the file export, e.g.:
target$ echo <N> > /sys/class/gpio/export
This will create a new subdirectory gpio<N> (for GPIO<X>_<Y> of the controller). The two files direction and value in the new subdirectory allow you to control the GPIO.
- To use, for example, GPIO <N> as input execute the following commands:
target$ echo in > /sys/class/gpio/gpio<N>/direction target$ cat /sys/class/gpio/gpio<N>/value
On the carrier board PBA-B-01 for the phyFLEX-i.MX 6, for example, this will toggle LED D105.
- For example, to use the newly created GPIO 135 as output and to toggle it, execute:
target$ echo 135 > /sys/class/gpio/export target$ echo out > /sys/class/gpio/gpio135/direction target$ echo 1 > /sys/class/gpio/gpio135/value target$ echo 0 > /sys/class/gpio/gpio135/value
On the carrier board PBA-B-01 for the phyFLEX-i.MX 6, for example, this will read pin 3 of GPIO connector X54.
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Some of the user IOs are used for special functions on the carrier boards (e.g. GPIO5_8, GPIO1_9 and GPIO7_12 on the PBA-B-01 CB). Before using a user IO refer to the schematic, or the hardware manual of your board to ensure that it is not already in use. |
Pinmuxing of some GPIO pins in the device tree imx6qdl-phytec-pbab01.dtsi:
pinctrl_hog: hoggrp { fsl,pins = < MX6QDL_PAD_EIM_D23__GPIO3_IO23 0x80000000 MX6QDL_PAD_DISP0_DAT3__GPIO4_IO24 0x80000000 /* SPI NOR chipselect */ MX6QDL_PAD_SD4_DAT1__GPIO2_IO09 0x80000000 /* PMIC interrupt */ MX6QDL_PAD_ENET_TXD0__GPIO1_IO30 0x80000000 /* Green LED */ MX6QDL_PAD_EIM_EB3__GPIO2_IO31 0x80000000 /* Red LED */ MX6QDL_PAD_GPIO_8__GPIO1_IO08 0x80000000 [...]
Keys
With gpio-keys the Linux kernel can interpret GPIO signals as virtual keyboard events. Some carrier boards have buttons, which can be used with the gpio-keys driver. By pushing a button an interrupt is triggered which causes the system to handle the corresponding keyboard event.
To display the key events in ASCII format, use evtest':
- To show the available input devices run:
target$ evtest
You will get for example: No device specified, trying to scan all of /dev/input/event* Available devices: /dev/input/event0: stmpe-ts /dev/input/event1: gpio-keys Select the device event number [0-1]:
- Select input device gpio-keys
- Listening to the device with cat will print the raw output:
target$ cat /dev/input/event1
GPIO-Keys configuration in imx6qdl-phytec-mira-peb-eval-01.dtsi:
&iomuxc { imx6qdl-phytec-mira-pebeval01 { pinctrl_gpio_keys: gpio_keysgrp { fsl,pins = < MX6QDL_PAD_SD3_DAT6__GPIO6_IO18 0x80000000 MX6QDL_PAD_CSI0_DAT10__GPIO5_IO28 0x80000000 >; }; }; }; / { gpio-keys { compatible = "gpio-key"; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_gpio_keys>; status = "disabled"; home { label = "Home"; gpios = <&gpio6 18 GPIO_ACTIVE_LOW>; linux,code = <KEY_HOME>; }; power { label = "Power Button"; gpios = <&gpio5 28 GPIO_ACTIVE_LOW>; linux,code = <KEY_POWER>; gpio-key,wakeup; }; }; };
LEDS
In case that LEDs are being connected to GPIOs, you have the possibility to access them by a special LED driver interface instead of the general GPIO interface (section "GPIOs"). You will then access them using /sys/class/leds/ instead of /sys/class/gpio/. The maximum brightness of the LEDs can be read from the max_brightness file. The brightness file will set the brightness of the LED (taking a value from 0 up to max_brightness). Most LEDs do not have hardware brightness support and thus will just be turned on by all non-zero brightness settings.
Here is a simple example for the phyBOARD-Mira:
- To get all LEDs available, type:
target$ ls /sys/class/leds
mmc0:: phycore:green user_led_red mmc1:: user_led_green user_led_yellow
- To toogle the LEDs use
target$ echo 255 > /sys/class/leds/user_led_green/brightness
to turn it ON, and
target$ echo 0 > /sys/class/leds/user_led_green/brightness
to turn it OFF.
User I/O configuration in device tree file arch/arm/boot/dts/imx6qdl-phytec-mira-peb-eval-01.dtsi:
&iomuxc { imx6qdl-phytec-mira-pebeval01 { pinctrl_user_leds: user_ledsgrp { fsl,pins = < MX6QDL_PAD_SD3_DAT4__GPIO7_IO01 0x80000000 MX6QDL_PAD_SD3_DAT5__GPIO7_IO00 0x80000000 MX6QDL_PAD_CSI0_DAT11__GPIO5_IO29 0x80000000 >; }; }; }; / { user_leds: user_leds { compatible = "gpio-leds"; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_user_leds>; status = "disabled"; user_led_green { gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>; linux,default-trigger = "gpio"; default-state = "on"; }; user_led_yellow { gpios = <&gpio7 0 GPIO_ACTIVE_HIGH>; linux,default-trigger = "gpio"; default-state = "on"; }; user_led_red { gpios = <&gpio7 1 GPIO_ACTIVE_HIGH>; linux,default-trigger = "gpio"; default-state = "on"; }; }; };
SPI Master
Most PHYTEC boards are equipped with a NOR Flash which connects to the i.MX 6's ECSPI interface. The NOR Flash is suitable for booting (section "Booting from SPI NOR Flash").
From Linux user space the NOR Flash partitions start with dev/mtdblock5 (see mtdinfo -v). There are currently four partitions: barebox, barebox-environment, oftree and kernel. Please note that there is no root filesystem partition on the NOR Flash.
The partitions of an SPI Flash are defined in all DTs, but the barebox bootloader overwrites only the partitions of the kernel device tree. Thus, changing the partitions has to be done either in the barebox DT, or in the barebox environment. How to modify the partitions during runtime in the barebox environment is described in section "Changing MTD Partitions".
Adding new partitions can be done, for example in imx6qdl-phytec-pfla02.dtsi, by creating a new partition node. The property label defines the name of the partition and the reg value the offset and size of a partition. Do not forget to update all following partitions when adding a partition, or changing a partition's size.
The flash node is defined inside of the SPI master node in the module DTs. The SPI node contains all devices connected to this SPI bus which is in this case only the SPI NOR Flash.
Definition of the SPI master node with the partition layout, e.g. in imx6qdl-phytec-pfla02.dtsi:
&iomuxc { imx6q-phytec-pfla02 { pinctrl_ecspi3: ecspi3grp { fsl,pins = < MX6QDL_PAD_DISP0_DAT0__ECSPI3_SCLK 0x100b1 MX6QDL_PAD_DISP0_DAT2__ECSPI3_MISO 0x100b1 MX6QDL_PAD_DISP0_DAT1__ECSPI3_MOSI 0x100b1 MX6QDL_PAD_DISP0_DAT3__GPIO4_IO24 0x80000000 MX6QDL_PAD_DISP0_DAT4__GPIO4_IO25 0x80000000 MX6QDL_PAD_DISP0_DAT5__GPIO4_IO26 0x80000000 >; }; }; }; &ecspi3 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_ecspi3>; status = "okay"; fsl,spi-num-chipselects = <1>; cs-gpios = <&gpio4 24 0>; flash@0 { compatible = "m25p80"; spi-max-frequency = <20000000>; reg = <0>; #address-cells = <1>; #size-cells = <1>; partition@0 { label = "barebox"; reg = <0x0 0x100000>; }; partition@1 { label = "barebox-environment"; reg = <0x100000 0x20000>; }; partition@2 { label = "oftree"; reg = <0x120000 0x20000>; }; partition@3 { label = "kernel"; reg = <0x140000 0x0>; }; }; };
The imx6qdl-phytec-pbab01.dtsi also includes an example for an spidev device. This node has been enabled in the phyFLEX-i.MX 6 RDK. spidev allows you to access an SPI device directly from user space.
&ecspi3 { spi@1 { compatible = "spidev"; spi-max-frequency = <57600000>; reg = <1>; }; spi@2 { compatible = "spidev"; spi-max-frequency = <57600000>; reg = <2>; }; };
The partition layout is also available in the kernel as a fallback, e.g. imx6qdl phytec pfla02.dtsi.
I²C Bus
The i.MX 6 contains three multimaster fast-mode I²C modules called I2C1, I2C2, and I2C3. PHYTEC boards provide plenty of different I²C devices connected to the three I²C modules of the i.MX 6. This chapter will describe the basic device usage and its DT representation of some of the I²C devices integrated on our RDK boards.
General I²C bus configuration (e.g. imx6q-phytec-phycard-imx6-som.dtsi):
&i2c1 { status = "okay"; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_i2c1>; /* ... */ }; &iomuxc { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_hog>; imx6q-phytec-pcaaxl3 { pinctrl_i2c1: i2c1grp { fsl,pins = < MX6QDL_PAD_EIM_D21__I2C1_SCL 0x4001b8b1 MX6QDL_PAD_EIM_D28__I2C1_SDA 0x4001b8b1 >; }; }; };
EEPROM
It is possible to read and write directly to the device:
/sys/class/i2c-dev/i2c-0/device/0-0050/eeprom
- E.g. to read and print the first 1024 bytes of the EEPROM as hex number execute:
target$ dd if=/sys/class/i2c-dev/i2c-0/device/0-0050/eeprom bs=1 count=1024 | od -x
- To fill the whole EEPROM with zeros use:
target$ dd if=/dev/zero of=/sys/class/i2c-dev/i2c-0/device/0-0050/eeprom bs=4096 count=1
This operation takes some time because the EEPROM is relatively slow.
DT representation, e.g. in phyFLEX-i.MX 6 file imx6qdl-phytec-pfla02.dtsi:
eeprom@50 { compatible = "atmel,24c32"; reg = <0x50>; };
RTC
RTCs can be accessed via /dev/rtc*. Because PHYTEC boards have often more than one RTC, there might be more than one RTC device file.
- To find out the name of the RTC device you can read its sysfs entry with:
target$ cat /sys/class/rtc/rtc*/name
You will get for example:
rtc-pcf8563 da9063-rtc 20cc034.snvs-rtc-lp
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This will list all RTCs including the non-I²C RTCs. Linux assigns RTC devices IDs based on the device tree /aliases entries if present. |
imx6q-phytec-phycard-imx6-som.dtsi
aliases { ipu0 = &ipu1; ipu1 = &ipu2; rtc1 = &pmic; rtc2 = &snvs_rtc; };
imx6q-phytec-phycard-imx6-rdk.dts:
aliases { rtc0 = &i2c_rtc; };
As the time is set according to the value of rtc0 during system boot rtc0 should be always the RTC that is being backed up.
Date and time can be manipulated with the hwclock tool, using the -w (systohc) and -s (hctosys) options.
To set the date first use date and then run hwclock -w -u to store the new date into the RTC. For more information about this tool refer to the manpage of hwclock.
DT representation for I²C RTCs: imx6q-phytec-phycard-imx6-rdk.dts:
i2c_rtc: rtc@51 { compatible = "nxp,rtc8564"; reg = <0x51>; };
Capacitive Touchscreen
The capacitive touchscreen is a part of the display module.
- For a simple test of this feature start our demo application with:
target$ qtLauncher QtDemo
This application also includes a Multitouch Demo.
- To start another more simple test application type:
target$ qt5-opengles2-test
- To test the basic input handling of the touchscreen use evtest after selecting an input device:
target$ evtest
The raw touch input events will be displayed.
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The display DT representation for all displays implemented so far, are summarized in imx6qdl-phytec-lcd.dtsi. |
DT representation, e.g. in imx6qdl-phytec-pbab01.dtsi:
&i2c2 { polytouch: edt-ft5x06@38 { compatible = "edt,edt-ft5406", "edt,edt-ft5x06"; reg = <0x38>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_edt_ft5x06>; interrupt-parent = <&gpio7>; interrupts = <12 0>; }; […] }; &iomuxc { imx6q-phytec-pfla02 { pinctrl_edt_ft5x06: edt_ft5x06grp { fsl,pins = <MX6QDL_PAD_GPIO_17__GPIO7_IO12 0x80000000>; }; […] }; };
LED Dimmer
All LED dimmer controlled LEDs can be accessed through the sysfs. Here is a simple example:
- Use the ls command to list all LEDs:
target$ ls /sys/class/leds/
You will get:
green:user4 phyflex:green red:user1 mmc0:: phyflex:red yellow:user2 mmc1:: phyflex:user_led_gpio yellow:user3
- To turn on the red user LED1 write 255 to the corresponding file:
target$ echo 255 > /sys/class/leds/red\:user1/brightness
- To turn off the red user LED1 write 0 to the corresponding file:
target$ echo 0 > /sys/class/leds/red\:user1/brightness
Currently, only the GPIO functionality is used with the PCA9533. So you can only switch the LEDs on and off. The dimming feature of the PCA9533 is not yet tested.
DT representation, e.g. in imx6qdl-phytec-pbab01.dtsi:
leddim: leddimmer@62 { compatible = "nxp,pca9533"; gpio-controller; #gpio-cells = <2>; nxp,typecodes = <0xFF>; nxp,statecodes = <0x55>; reg = <0x62>; };
As you can see, the LED dimmer is a gpio-controller node. The PCA9533 controlled LEDs can be used within a gpio-led driver. Please read the related binding documentation in documentation/devicetree/bindings/ for more information about gpio-controller and gpio-leds.
&user_leds_pca9533 { led1 { label = "red:user1"; gpios = <&leddim 0 0>; linux,default-trigger = "none"; default-state = "on"; }; led2 { label = "yellow:user2"; gpios = <&leddim 1 0>; linux,default-trigger = "none"; default-state = "on"; }; led3 { label = "yellow:user3"; gpios = <&leddim 2 0>; linux,default-trigger = "none"; default-state = "on"; }; led4 { label = "green:user4"; gpios = <&leddim 3 0>; linux,default-trigger = "none"; default-state = "on"; }; };
LEDs are exported to the sysfs /sys/class/leds/.
USB Host Controller
The USB controller of the i.MX 6 SoC provides a low-cost connectivity solution for numerous consumer portable devices by providing a mechanism for data transfer between USB devices with a line/bus speed up to 480 Mbps. The USB subsystem has four independent USB controller cores. The first core is an On-The-Go (OTG) controller core and capable of acting as a USB peripheral device, or USB host. The second, third and fourth core are host-only controller cores. Only the first and the second core are connected to two USB 2.0 PHY macrocells. The third and fourth core only supports HSIC interfaces.
The unified BSP includes support for mass storage devices and keyboards. Other USB related device drivers must be enabled in the kernel configuration on demand.
Due to udev, all mass storage devices connected get unique IDs and can be found in /dev/disks/by-id. These IDs can be used in /etc/fstab to mount the different USB memory devices in different ways.
User USB1 (host) configuration in the kernel device tree imx6qdl-phytec-pfla02.dtsi:
[…] pinctrl_usbh1: usbh1grp { fsl,pins = < MX6QDL_PAD_GPIO_0__GPIO1_IO00 0x80000000 MX6QDL_PAD_GPIO_3__USB_H1_OC 0x1b0b0 >; }; […] &usbh1 { vbus-supply = <®_usb_h1_vbus>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_usbh1>; status = "disabled"; };
Kernel device tree imx6qdl-phytec-pbab01.dtsi:
&usbh1 { status = "okay"; };
USB OTG
Most PHYTEC boards provide a USB OTG interface. USB OTG ports automatically act as a USB device or USB host. The mode depends on the USB hardware attached to the USB OTG port. If, for example, a USB mass storage device is attached to the USB OTG port, the device will show up as /dev/sda.
USB Device
In order to connect the board as USB device to a USB host port (for example a PC), you need to configure the appropriate USB gadget. With USB configfs you can define the parameters and functions of the usb gadget. The BSP includes USB configfs support as a kernel module.
target$ modprobe libcompositeExample:
- First define the parameters such as the USB vendor and product IDs, and set the information strings for the english (0x409) language:
target$ cd /sys/kernel/config/usb_gadget/ target$ mkdir g1 target$ cd g1/ target$ echo "0x1d6b" > idVendor target$ echo "0x0104" > idProduct target$ mkdir strings/0x409 target$ echo "0123456789" > strings/0x409/serialnumber target$ echo "Foo Inc." > strings/0x409/manufacturer target$ echo "Bar Gadget" > strings/0x409/product
- Next create a file for the mass storage gadget:
target$ dd if=/dev/zero of=/tmp/file.img bs=1M count=64
- Now you should create the functions you want to use:
target$ cd /sys/kernel/config/usb_gadget/g1 target$ mkdir functions/acm.GS0 target$ mkdir functions/ecm.usb0 target$ mkdir functions/mass_storage.0 target$ echo /tmp/file.img > functions/mass_storage.0/lun.0/file
- acm: Serial gadget, creates serial interface like /dev/ttyGS0. - ecm: Ethernet gadget, creates ethernet interface, e.g. usb0 - mass_storage: The host can partition, format and mount the gadget mass storage the same way as any other USB mass storage.
- Bind the defined functions to a configuration with:
target$ cd /sys/kernel/config/usb_gadget/g1 target$ mkdir configs/c.1 target$ mkdir configs/c.1/strings/0x409 target$ echo "CDC ACM+ECM+MS" > configs/c.1/strings/0x409/configuration target$ ln -s functions/acm.GS0 configs/c.1/ target$ ln -s functions/ecm.usb0 configs/c.1/ target$ ln -s functions/mass_storage.0 configs/c.1/
- Finally start the USB gadget with the following commands:
target$ cd /sys/kernel/config/usb_gadget/g1 target$ ls /sys/class/udc/ ci_hdrc.0 target$ echo "ci_hdrc.0" >UDC
If your system has more than one USB Device or OTG port, you can pass the right one to the USB Device Controller (UDC).
- To stop the USB gadget and unbind the used functions execute:
target$ echo "" > /sys/kernel/config/usb_gadget/g1/UDC
User USB OTG configuration in the kernel device tree imx6qdl-phytec-pfla02.dtsi:
&iomuxc { imx6q-phytec-pfla02 { pinctrl_usbotg: usbotggrp { fsl,pins = < MX6QDL_PAD_GPIO_1__USB_OTG_ID 0x17059 MX6QDL_PAD_KEY_COL4__USB_OTG_OC 0x1b0b0 MX6QDL_PAD_KEY_ROW4__GPIO4_IO15 0x80000000 >; }; }; }; &usbotg { vbus-supply = <®_usb_otg_vbus>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_usbotg>; disable-over-current; status = "disabled"; };
Kernel device tree imx6qdl-phytec-pbab01.dtsi:
&usbotg { status = "okay"; dr_mode = "peripheral"; };
SATA
Some boards like the phyFLEX-i.MX 6 Kit feature a SATA connecter (Serial ATA) which is used to attach hard disks, or optical drives.
As in any other Linux system a SATA hard disk will show up as a standard block device (/dev/sda in the following example) after connecting.
- E.g. type:
target$ ls -l /dev/sda*
You will get something like:
brw-rw---- 1 root disk 8, 0 May 27 07:56 /dev/sda brw-rw---- 1 root disk 8, 1 May 27 07:56 /dev/sda1
The disk can be partitioned and formatted like any other block device.
To access the partitions you can also use the persistent block device naming in /dev/disk/ (ArchLinux Wiki-Persistent block device naming).
PCIe
Some PHYTEC boards feature a PCIe- or Mini-PCIe-Slot.
In general PCIe autodetects new devices on the bus. After connecting the device and booting up the system you can use the command lspci to see all PCIe devices recognized.
- Type:
target$ lspci -v
You will receive:
00:00.0 PCI bridge: Device 16c3:abcd (rev 01) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0
Memory at 01000000 (32-bit, non-prefetchable) [size=1M]
Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
I/O behind bridge: 00001000-00001fff
Prefetchable memory behind bridge: 01100000-011fffff
[virtual] Expansion ROM at 01200000 [disabled] [size=64K]
Capabilities: [40] Power Management version 3
Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
Capabilities: [70] Express Root Port (Slot-), MSI 00
Capabilities: [100] Advanced Error Reporting
Capabilities: [140] Virtual Channel
Kernel driver in use: pcieport
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
Subsystem: Realtek Semiconductor Co., Ltd. Device 0123
Flags: bus master, fast devsel, latency 0, IRQ 308
I/O ports at 1000 [size=256]
Memory at 01104000 (64-bit, prefetchable) [size=4K]
Memory at 01100000 (64-bit, prefetchable) [size=16K]
Capabilities: [40] Power Management version 3
Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
Capabilities: [70] Express Endpoint, MSI 01
Capabilities: [b0] MSI-X: Enable- Count=4 Masked-
Capabilities: [d0] Vital Product Data
Capabilities: [100] Advanced Error Reporting
Capabilities: [140] Virtual Channel
Capabilities: [160] Device Serial Number ef-ba-00-00-68-4c-e0-00
Kernel driver in use: r8169
Kernel modules: r8169
In this example, the PCIe device is the RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller.
For PCIe devices, you have to enable the correct driver in the kernel configuration. This Ethenet card, for example, is manufactured by Realtek Semiconductor Co.and the corresponding Kconfig option for the driver, which must be enabled, is named CONFIG_R8169 and can be found under Realtek 8169 gigabit ethernet support in the kernel configuration.
- In order to activate the driver use:
host$ bitbake virtual/kernel -c menuconfig
For some devices like this Ethernet card, additional binary firmware blobs are needed. For example, if you try to bring up the network interface with:
target$ ip link set up enp1s0
you will get the following output on the serial console:
[ 620.116794] r8169 0000:01:00.0: Direct firmware load for rtl_nic/rtl8168e-3.fw failed with error -2 [ 620.125943] r8169 0000:01:00.0 enp1s0: unable to load firmware patch rtl_nic/rtl8168e-3.fw (-2) [ 620.163733] r8169 0000:01:00.0 enp1s0: link down [ 620.168703] r8169 0000:01:00.0 enp1s0: link down [ 620.178436] IPv6: ADDRCONF(NETDEV_UP): enp1s0: link is not ready
These firmware blobs have to be placed in /lib/firmware/ before the device can be used.
- E.g. with:
host$ scp -r <firmware> root@192.168.3.11:/lib/firmware
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Some PCIe devices, e.g. this Ethernet card, may function properly even if no firmware blob could be loaded from /lib/firmware/ and you received an error message as shown in the first line of the output above. This is because some manufacturers provide the firmware as fall-back on the card itself. In this case, the behavior and output depend strongly on the manufacturer's firmware. |
Audio
On PHYTEC i.MX 6 boards different audio chips are used. This section is written for the phyFLEX Carrier Board (PBA-B-01) with the TI TLV320AIC3007 audio codec, but it should be applicable for other boards and audio chips as well.
Audio support is done via the I2S interface and controlled via I2C.
- To check if your soundcard driver is loaded correctly and what the device is called type:
target$ aplay -L
- Use scp to copy a wav file to the board and play it through the sound interface with:
target$ aplay -vv file.wav
Not all wave formats are supported by the sound interface. Use Audacity on your host to convert any file into 44100:S16_LE wave format which should be supported on all platforms.
- Run speaker-test to identify channel numbers:
target$ speaker-test -c 2 -t wav
- An external audio source can be connected to the input, in order to record a sound file which can then be played back:
target$ arecord -c 2 -r 441000 -f S16_LE test.wav target$ aplay test.wav
- To inspect your soundcards capabilities call:
target$ alsamixer
You should see a lot of options as the audio-ICs have many features you can play with. It might be better to open alsamixer via ssh instead of the serial console, as the console graphical effects could be better. You have either mono or stereo gain controls for all mix points. "MM" means the feature is muted, which can be toggled by hitting m.
For more advanced audio usage, you need to have an audio server. This is required e.g. if you want to playback from different applications at the same time, e.g. you a have a notification app which makes a beep every now and then, plus you have a browser running which should be able to play sounds embedded in websites. The notification app has no possibility to open the sound device as long as the browser is running. The notifications will be suppressed. The standard sound server of Linux is pulseaudio. It is not installed per default at the moment, though.
Audio Sources and Sinks
The baseboard has four jacks for microphone, headset speaker, line in and line out.
Enabling and disabling input and output channels can be done with the alsamixer program. F3 selects Screen Playback and F4 Screen Capture. With the Tabulator key you can switch between these screens. To enable, or disable switchable controls press m (mute).
With the keys cursor left and cursor right, you can step through the different channels. There are much more channels than fit onto one screen, so they will scroll if your cursor reaches the right or left edge of it. In case you get trouble in the display during scrolling, please use ssh instead of microcom.
alsamixer can be left by pressing the ESC key. The settings are saved automatically on shutdown and restored on boot by the systemd service alsa-restore. If you want to save the mixer settings manually you can execute aslactl store. The settings are saved in /var/lib/alsa/asound.state.
Playback
To playback simple audio streams, you can use aplay. For example:
target$ aplay /usr/share/sounds/alsa/Front_Center.wav
The file formats .ogg, and .flac can be played back using ogg123. MP3 playback is currently not supported per default, because of licensing issues. If you are going to deliver a product including .mp3 files, please check the royalty fees.
Capture
arecord is a command line tool for capturing audio streams which uses Line In as default input source.
To select a different audio source you can use alsamixer. For examle, switch on Right PGA Mixer Mic3R and Left PGA Mixer Mic3L in order to capture the audio from the microphone input.
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It is a known error that you need to choose Playback screen (F3) instead of Capture screen (F4) for accessing these two controls. |
The following example will capture the current stereo input source with a sample rate of 48000 Hz and will create an audio file in WAV format (signed 16 bit per channel, 32 bit per sample):
target$ arecord -t wav -c 2 -r 48000 -f S16_LE test.wav
Capturing can be stopped again using CTRL-C.
Texas Instruments TLV320AIC3007 (phyFLEX-i.MX6, phyCARD-i.MX 6)
The TI chip has a lot of mixing features as you will notice when opening alsamixer. To get an idea of the possibilities, refer to the datasheet from TI. One important feature is the analog mixing capability. You can route input channels to output channels either active or passive without transferring data back and forth to the SoC. This is usually known as zero latency monitoring in terms of PC Audio cards. To control this feature open alsamixer and go to Playback section (F3). There will be one group of selectors for each output channel, e.g. Right Line Mixer. For most of the input paths you can select between "passive through", or you can activate a programmable gain signal path. To route the line input to the line output, activate both "Right Line Mixer PGAR Bypass" and "Left Line Mixer PGAL Bypass". You should now hear the input signal at the line out.
As an example application, we can route the audio stream through the whole system. First, we deactivate the direct loop from line in to line out in alsamixer and activate the ADC for the analog input mixer and the DAC for the analog output mixer. We can now close the signal path in the user space by using a pipe and the ALSA tools:
target$ arecord -c 2 -r 44100 -f S16_LE | aplay
We created the following audio routing path:
analog in -> ADC -> i.MX 6 -> kernel -> (userspace -> kernel -> )* DAC -> analog out
* actually twice for the pipe
You should now hear the input signal at the line output again. But this time, the routing through the entire system added a latency of 750 ms to the signal. The line mixer on the other side will only add about 4 μs delay.
This pipe routing is a crude example of how to use audio. If you need good audio performance you should use an audio server. There are two prominent choices available, pulseaudio and jack.
As a third option, you can route the audio from line in to the internal ADC. But instead of taking the signal path through the complete system, you can directly use the internal digital mixer of the TLV to route the signal back to the DAC and then to the output analog mixer and line out. This signal path is record only. So you do not have the option of full-duplex playback in this mode, but you can use all the available DSP features of the TLV, the automatic gain, the high-pass filter, EQ and de-emphasis filters for the record path. To activate this mode you have to use the TI Windows tool to look up the specific I²C commands. The software can be found on the TI webpage and is called TLV320AIC3107EVM-K - GUI Software. The 3107 is register compatible in all available features to the 3007. The software is used for both chips.
Video
The i.MX 6 has a Video Processing Unit (VPU) which can decode and encode different video formats (for more information see the i.MX 6 Reference Manual). This chapter will show some gstreamer pipeline examples to play videos with different gstreamer plugins.
Videos with gstreamer plugin fbdevsink
There gstreamer plugins like decodebin and uridecodebin that automatically selects a suitable decoder and muxer for video file. You don't have to specify the video format and container format explicitly, but you still can set the output device/sink manually.
The following example uses decodebin for a VP8 encoded video. The video is installed by default on your images.
target$ gst-launch-1.0 filesrc location=/usr/share/phytec-qtdemo/videos/caminandes.webm \ ! decodebin \ ! videoconvert \ ! fbdevsink sync=false
The next examples uses uridecodebin for a h.264 encoded video. The plugin combines the elements filesrc and decodebin.
target$ gst-launch-1.0 uridecodebin uri=file:///tmp/big_buck_bunny_480p_h264.mov \ ! videoconvert \ ! fbdevsink sync=false
Videos with gstreamer plugin kmssink
The kmssink plugin needs a connector id. To get the connector id you can use the tool modetest.
- Get the connector-id
target$ modetest -cThe output will show something like:
trying to open device 'i915'...failed trying to open device 'radeon'...failed trying to open device 'nouveau'...failed trying to open device 'vmwgfx'...failed trying to open device 'omapdrm'...failed trying to open device 'exynos'...failed trying to open device 'tilcdc'...failed trying to open device 'msm'...failed trying to open device 'sti'...failed trying to open device 'tegra'...failed trying to open device 'imx-drm'...done Connectors: id encoder status name size (mm) modes encoders 32 31 connected HDMI-A-1 0x0 5 31 modes: name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot) 1024x768 60 1024 1048 1184 1344 768 771 777 806 flags: nhsync, nvsync; type: driver 800x600 60 800 840 968 1056 600 601 605 628 flags: phsync, pvsync; type: driver 800x600 56 800 824 896 1024 600 601 603 625 flags: phsync, pvsync; type: driver 848x480 60 848 864 976 1088 480 486 494 517 flags: phsync, pvsync; type: driver 640x480 60 640 656 752 800 480 489 492 525 flags: nhsync, nvsync; type: driver props: 1 EDID: flags: immutable blob blobs: value: 2 DPMS: flags: enum enums: On=0 Standby=1 Suspend=2 Off=3 value: 1
In this example the connector-id is 32.
... Connectors: id encoder status name size (mm) modes encoders 32 31 connected HDMI-A-1 0x0 5 31 ...
Automatic encoder selection
- Play video with:
target$ gst-launch-1.0 uridecodebin uri=file:///usr/share/phytec-qtdemo/videos/caminandes.webm ! \ videoscale ! \ videoconvert ! \ video/x-raw,width=800,height=400 ! \ kmssink connector-id=32 driver-name="imx-drm" sync=false scale=false
Playing Video with VPU
target$ gst-launch-1.0 filesrc location=big_buck_bunny_480p_h264.mov ! \
qtdemux ! \
h264parse ! \
v4l2video1videodec ! \
videoconvert ! \
videoscale ! \
video/x-raw,width=800,height=400 ! \
kmssink connector-id=32 driver-name="imx-drm" sync=false scale=false
Video streaming
target$ gst-launch-1.0 filesrc location=big_buck_bunny_480p_h264.mov ! \
qtdemux ! h264parse ! v4l2video1videodec ! \
jpegenc ! \
rtpjpegpay ! \
udpsink host=192.168.3.10 port=5200
host$ gst-launch-1.0 udpsrc port=5200 ! \ application/x-rtp,\ encoding-name=JPEG,payload=26 ! \ rtpjpegdepay ! \ jpegdec ! \ videoconvert ! \ videoscale ! \ ximagesink
Framebuffer
This driver gains access to displays connected to PHYTEC carrier boards via device node /dev/fb0.
The BSP is already prepared for use with the ETM0700G0DH6 (800 x 480) display, e.g. for the phyFLEX-i.MX 6 Kit. Other displays will be added in later BSP versions.
- To run a simple test of the framebuffer feature, execute:
fbtest
This will show various pictures on the display.
- Information about the framebuffer's resolution can be obtained with
fbset
which will return:
mode "800x480-0"
# D: 0.000 MHz, H: 0.000 kHz, V: 0.000 Hz
geometry 800 480 800 480 16
timings 0 0 0 0 0 0 0
accel true
rgba 5/11,6/5,5/0,0/0
endmode
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fbset cannot be used to change display resolution or color depth. Depending on the framebuffer device different kernel commands are mostly needed to do this.
Some documentation can be found in the kernel documentation at https://www.kernel.org/doc/Documentation/fb/modedb.txt. Please also refer to the manual of your display driver for more details. |
In the following section, you will find some more useful commands.
- To query the color depth of the framebuffer emulation type:
target$ cat /sys/class/graphics/fb0/bits_per_pixel
The result can be, for example:
16
- To get the name of the video interface execute:
traget$ ls /sys/class/drm/ -1
Possible output (e.g. for the phyFLEX i.MX 6 mounted on the phyFLEX Carrier Board PBA-B-01)):
card0 card0-HDMI-A-1 card0-LVDS-1 controlD64 version
The suffixes of "card0-*" are the identifiers which must be used to configure the corresponding interface.
- To set, for example, the HDMI interface to 1024 x 768 pixels and bits per pixel to 24 bpp, use the following kernel argument in the bootloader:
bootloader$ nv linux.bootargs.video="video=HDMI-A-1:1024x768-24" bootloader$ saveenv
| |
Ensure to use the correct bits per pixel for your display, e.g. 18, 16 or 24, … . Otherwise, the colors will look very strange. Use fbtest to test them. |
- An additional method to increase only the color depth of the framebuffer emulation with kernel arguments is:
bootloader$ nv linux.bootargs.fb="imxdrm.legacyfb_depth=32" bootloader$ saveenv
- If you have connected multiple displays to your board, for example, an LVDS and an HDMI display, you can disable one of them by setting
bootloader$ nv linux.bootargs.video="video=LVDS-1:d" bootloader$ saveenv
The display DT representation can be found in imx6qdl‑phytec‑lcd.dtsi. We have split the display configuration into two parts. In a generic display module imx6qdl‑phytec‑lcd.dtsi which includes the display DT representations for all displays implemented so far, and a board specific part, which can be found in all board DTs. The imx6qdl‑phytec‑lcd.dtsi file is included within the board DTs.
Board specific part, e.g. arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi:
&iomuxc {
imx6q-phytec-pfla02 {
pinctrl_pwm1: pwm1grp {
fsl,pins = <
MX6QDL_PAD_DISP0_DAT8__PWM1_OUT 0x1b0b1
>;
};
};
};
&pwm1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_pwm1>;
status = "okay";
};
Board specific part, e.g.arch/arm/boot/dts/imx6qdl-phytec-pbab01.dtsi
&backlight {
pwms = <&pwm1 0 5000000>;
enable-gpios = <&gpio1 8 GPIO_ACTIVE_LOW>;
brightness-levels = <0 4 8 16 32 64 128 255>;
};
Backlight Control
If a display is connected to the PHYTEC board, you can control its backlight with the Linux kernel sysfs interface. All available backlight devices in the system can be found in the folder /sys/class/backlight. Reading the appropriate files and writing to them allows you to control the backlight.
- To get, for example, the maximum brightness level (max_brightness) execute
target$ cd /sys/class/backlight/backlight/max_brightness target$ cat max_brightness
which will result in :
7
Valid brightness values are 0 to <max_brightness>.
- To obtain the current brightness level type
target$ cat brightness
you will get for example:
2
- Write to the file brightness to change the brightness. E.g.,
target$ echo 0 > brightness
turns the backlight off,
target$ echo 6 > brightness
Set brightness to the second highest brightness level.
For documentation of all files see https://www.kernel.org/doc/Documentation/ABI/stable/sysfs-class-backlight.
| |
If dimming does not work by writing to the file brightness, check the DIP switch settings on the bottom side of the display module (LCD-018). The correct setting of DIP switch S1 is 1=OFF, 2=OFF, 3=ON and 4=OFF.
This note applies to phyFLEX Kits with one of the following display modules: LCD-018-035-KAP, LCD-018-043-KAP, LCD-018-057-KAP, and LCD-018-070-KAP. |
Resistive Touchscreens
Most of the PHYTEC boards support connecting a resistive touchscreen which requires tslib support in general. But tslib support is also needed for the Qt framework for use of a resistive touchscreen, because tslib and Qt5 do not work together out of the box.
- To set the right environment when starting a Qt application, start it with our qtLauncher:
target$ qtLauncher QtDemo [optional QtDemo parameters]
The launcher will check, whether the touchscreen is calibrated or not. If not, it will automatically start the calibration program before starting your application.
- Recalibration of the touchscreen can be done after closing the Qt application by executing:
target$ ts_calibrate
CPU Core Frequency Scaling
The CPU in the i.MX 6 SoC is able to scale the clock frequency and the voltage. This is used to save power when the full performance of the CPU is not needed. Scaling the frequency and the voltage is referred to as 'Dynamic Voltage and Frequency Scaling' (DVFS).
The i.MX 6 BSP supports the DVFS feature. The Linux kernel provides a DVFS framework that allows each CPU core to have a min/max frequency and a governor that governs it. Depending on the i.MX 6 variant used several different frequencies are supported.
- Type
target$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
to get a complete list.
In case you have for example an i.MX 6 CPU with a maximum of approximately 1 GHz the result will be:
396000 792000 996000
The voltages are scaled according to the setup of the frequencies.
You can decrease the maximum frequency (e.g. to 792000),
target$ echo 792000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
or increase the minimum frequency (e.g. to 792000)
target$ echo 792000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
- To ask for the current frequency type:
target$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
So called governors are selecting one of this frequencies in accordance to their goals, automatically.
- List all governors available with the following command:
target$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
The result will be:
conservative userspace powersave ondemand performance
- conservative is much like the ondemand governor. It differs in behavior in that it gracefully increases and decreases the CPU speed rather than jumping to max speed the moment there is any load on the CPU.
- userspace allows the user or user space program running as root to set a specific frequency (e.g. to 792000). Type:
target$ echo 792000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
- powersave always selects the lowest possible CPU core frequency.
- ondemand switches between possible CPU core frequencies in reference to the current system load. When the system load increases above a specific limit it increases the CPU core frequency immediately. This is the default governor when the system starts up.
- performance always selects the highest possible CPU core frequency.
- In order to ask for the current governor, type:
target$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
You will normally get:
ondemand
- Switching over to another governor (e.g. userspace) is done with:
target$ echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
For more detailed information about the governors refer to the Linux kernel documentation in: linux/Documentation/cpu-freq/governors.txt.
CPU Core Management
The i.MX 6 SoC can have multiple processor cores on the die. The i.MX 6 Quad, for example, has 4 ARM Cores which can be turned on and off individually at runtime.
- To see all available cores in the system execute:
target$ ls /sys/devices/system/cpu -1
This will show for example:
cpu0 cpu1 cpu2 cpu3 cpufreq [...]
Here the system has four processor cores.
By default, all available cores in the system are enabled to get the maximum performance.
- To switch off a single core execute:
target$ echo 0 > /sys/devices/system/cpu/cpu3/online
As confirmation you will see:
[ 69.380888] CPU3: shutdown
Now the core is powered down and no more processes are scheduled on this core.
- You can use htop to see a graphical overview of the cores and processes.
target$ htop
- To power up the core again, execute:
target$ echo 1 > /sys/devices/system/cpu/cpu3/online
Use of the kernel boot parameter maxcpus allows you to limit the number of cores the system is using at runtime (https://www.kernel.org/doc/Documentation/kernel-parameters.txt).
Watchdog
The PHYTEC i.MX6 Modules includes a hardware watchdog which is able to reset the board when the system hangs. Support for this is already partly activated in the i.MX6 BSP. This chapter will explain how to enable full support based on a root filesystem using systemd. The kernel driver expects a user space to "ping" the watchdog in regular bases. As user space setups may handle this differently, we have not activated this for the whole system.
Watchdog Support in the Barebox Bootloader
The watchdog is enabled when the boot command is launched. The timeout of the watchdog is set with the persistent nv variable in boot.watchdog_timeout. The default value is 60 s.
- If the value should be changed edit the file boot.watchdog_timeout with:
bootloader$ edit /env/nv/boot.watchdog_timeout
- Or change the variable with the nv command:
bootloader$ nv boot.watchdog_timeout=<time, e.g. 30s>
- Then save the changes with saveenv.
It is also possible to enable the watchdog manually at the barebox prompt using the wd <timeout> command. Executing the wd command without any parameter retriggers the watchdog. Disabling the watchdog again can be done with wd 0.
Watchdog Support in systemd
Systemd does include hardware watchdog support since version 183.
- To activate watchdog support the file system.conf in /etc/systemd/ has to be adapted by enabling the options:
RuntimeWatchdogSec=60s ShutdownWatchdogSec=10min
RuntimeWatchdogSec defines the timeout value of the watchdog, while ShutdownWatchdogSec defines the timeout when the system is rebooted.
For more detailed information about hardware watchdogs under systemd refer to http://0pointer.de/blog/projects/watchdog.html
Thermal Management
The Linux kernel has an integrated thermal management which is capable of monitoring SoC temperatures, reducing the CPU frequency, driving fans, advising other drivers to reduce the power consumption of devices and – in the worst case – shutting down the system gracefully (https://www.kernel.org/doc/Documentation/thermal/sysfs-api.txt).
This section describes how the thermal management kernel API is used for the i.MX 6 SoC platform.
The i.MX 6 has internal temperature sensors for the SoC ("Temperature Monitor (TEMPMON)" in the i.MX 6 Reference Manual).
- The current temperature can be read in millicelsius with:
target$ cat /sys/class/thermal/thermal_zone0/temp
You will get for example:
77535
There are two trip points registered by the imx_thermal kernel driver:
- trip_point_0: 85 °C type: passive
- trip_point_1: 105 °C type: critical
(see kernel sysfs folder /sys/class/thermal/thermal_zone0/)
These trip points are used by the kernel thermal management to trigger events and change the cooling behavior.
The following thermal policies (also named thermal governors) are available in the kernel:Step Wise, Fair Share, Bang Bang and User space.
The default policy used in the BSP is step_wise.
If the value of the SoC temperature in the sysfs file temp is above trip_point_0 (greater than 85 °C) the CPU frequency is set to the lowest CPU frequency. When the SoC temperature drops below trip_point_0 again, the throttling is released.
If the SoC temperature reaches 105 °C, the thermal management of the kernel shuts down the systems. On the serial console you can see:
kernel[194]: [ 895.524255] thermal thermal_zone0: critical temperature reached(105 C),shutting down
[ OK ] Stopped target Sound Card.
[ OK ] Stopped target System Time Synchronized.
[ OK ] Stopped target Network.
Stopping Autostart Qt 5 Demo...
[...]
See Linux mainline patch: HACK: thermal: imx: force maximum cooling above passive trip point
On-Chip OTP Controller (OCOTP_CTRL) - eFuses
The i.MX 6 provides one-time programmable fuses to store information such as the MAC address, boot configuration and other permanent settings ("On-Chip OTP Controller (OCOTP_CTRL)" in the i.MX 6 References Manual).
The following list is an abstract from the i.MX 6 Solo/DualLite Reference Manual and includes some useful fuse registers in the OCOTP_CTRL (at base address 0x21BC000):
| Name | ADDR | Memory offset to 0x21BC000 | /dev/imx-ocotp | Description |
|---|---|---|---|---|
| OCOTP_CFG4 | 0x05 | 0x450 | 0x14 | contains BOOT_CFG[1,2,3,4]. Transferred to register SRC_SBMR1 0x20D8004 |
| OCOTP_CFG5 | 0x06 | 0x460 | 0x18 | contains BT_FUSE_SEL at the fifths bit. Some bits are transferred to register SRC_SBMR2 0x20D801C |
| OCOTP_MAC0 | 0x22 | 0x620 | 0x88 | contains bits 0-31 of MAC_ADDR |
| OCOTP_MAC1 | 0x23 | 0x630 | 0x8C | contains bits 32-47 of MAC_ADDR |
| OCOTP_GP1 | 0x26 | 0x660 | 0x98 | general purpose register 1 |
| OCOTP_GP2 | 0x27 | 0x670 | 0x9C | general purpose register 1 |
A complete list and a detailed mapping between the fuses in the OCOTP_CTRL and the boot/mac/... configuration are available in section "Fusemap" of the i.MX 6 Reference Manual.
Reading Fuse Values in Barebox
You can read the content of a fuse using memory mapped shadow registers.
To calculate the memory address use the fuse address ADDR (0x01-0x2F) in the following formula:
memory address = 0x21BC400 + <ADDR> * 0x10
- In the barebox use md to read the value. Examples:
bootloader$ md 0x21BC450+4
reads OCOTP_CFG4: addr 0x05
bootloader$ md 0x21BC460+4
reads OCOTP_CFG5: addr 0x06
bootloader$ md 0x21BC620+4
reads OCOTP_MAC0: addr 0x22
bootloader$ md 0x21BC630+4
reads OCOTP_MAC1: addr 0x23
Burning Boot Configuration Fuses
| |
Fuses can only be written once! You can brick your board easily, e.g. by burning a wrong boot configuration. It cannot be reversed! |
Execute the following commands on the barebox prompt to burn the BOOT_CFG1-4 values and enable reading the boot configuration from fuses. To select a boot device of your choice, replace the BOOT_CFG1-4 value with the appropriate value for your boot device (eMMC, SD, SPI, NAND, etc.).
- First enable write to fuses with:
bootloader$ ocotp0.permanent_write_enable=1
- Then check values:
bootloader$ devinfo ocotp0
- Finally burn the fuses:
bootloader$ mw -l -d /dev/imx-ocotp 0x14 0x58003283
writes OCOTP_CFG4: BOOT_CFG1-4 Here: NAND 2Gb 64 pages per block (replace with the actual boot config of your board).
bootloader$ mw -l -d /dev/imx-ocotp 0x18 0x00000010
writes OCOTP_CFG5: Set bit BT_FUSE_SEL
Here is a short overview of different BOOT_CFG1-4 values for various boards and boot configurations:
| SRC_SBMR1 Register (0x20D8004) | Module and Boot configuration |
|---|---|
| 0x58003283 | NAND 2 Gb 64 pages per block on phyFLEX-i.MX 6/phyCORE-i.MX 6 |
| 0x58005863 | eMMC usdhc4 on phyCORE-i.MX 6 |
| 0x58002243 | SD Card usdhc1 on phyCORE-i.MX 6 |
It is possible to read out a valid boot configuration from a board instead of deriving it from the i.MX 6 Reference Manual. For this purpose boot the board from the boot source you want to configure in the fuses. Press any key to stop autoboot and execute:
bootloader$ md 0x20D8004+4 020d8004: 58002243 C".X
The command has read the value of register SRC_SBMR1 (here 0x58002243) which represents the boot configuration BOOT_CFG1-4, and which can be written to the fuse register OCOTP_CFG4 as described above.
Burning MAC Address
| |
Fuses can only be written once! You can brick your board easily, e.g. by burning a wrong boot configuration. It cannot be reversed! |
To burn the MAC address you do not have to blow the two fuse registers (OCOTP_MAC0 and OCOTP_MAC1) manually. The barebox ocotp drivers has a special command for that. The following sequence shows how to use it. Replace the dummy MAC address in the following commands with a valid MAC address from your pool of addresses.
- First enable write to fuses with:
bootloader$ ocotp0.permanent_write_enable=1
- Then check values:
bootloader$ devinfo ocotp0
- Finally burn the MAC address:
bootloader$ ocotp0.mac_addr=22:33:44:55:66:77
When burning a mac address with X116 in the first byte will create a multicast address! This one is not assignable as ip address.
WLAN Modules
Supported Wi-Fi Modules and Software used
Currently, there is only one module supported. The BSP described herein allows to run the TiWi-BLE Bluetooth and Wi-Fi combo module in client and Access Point (AP) mode using WEP, WPA and WPA2 encryption. More information about the module can be found at https://www.lsr.com/embedded-wireless-modules/wifi-plus-bluetooth-module/tiwi-ble
This BSP is using the most current firmware from the linux-firmware repository.
git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
The following binaries are used:
wl127x-fw-5-mr.bin (multi role) wl127x-fw-5-sr.bin (single role) wl127x-fw-5-plt.bin (used for the calibration process)
The Linux kernel driver will select the right firmware.
| |
We are using a self generated nvs binary file to allow the TiWi-BLE combo module to operate in compliance with the modular certification for FCC and ETSI. We have also set the MAC in the nvs file to 00:00:00:00:00:00. This causes the driver to use the MAC from the BT BD address that is burned into the wl127x chip. |
The wl1271-nvs.bin can be generated by using TI's calibrator tool and our ini file in
/usr/share/wl127x-inis/tiwi-ble-fcc-etsi.ini
Please see section "Calibration", or http://www.lsr.com/downloads/products/330-0078.pdf (chapter 2.2) for more information.
Enable Wi-Fi Expansion Boards
The current BSP supports two expansion boards with the TiWi-BLE Bluetooth and Wi-Fi combo module. The supported expansion boards are:
| Expansion Board article # | Description |
|---|---|
| PEB-B-001 | Expansion board suitable for phyBOARD-Subra i.MX 6 |
| PEB-WLBT-01 | Expansion board suitable for phyBOARD-Mira i.MX 6 |
To enable the expansion board on the phyBOARD-Subra, perform the following steps:
- Copy special device tree zImage-imx6dl-phytec-phyboard-subra-wifi.dtb (for the i.MX 6 DualLite/Solo), or zImage-imx6q-phytec-phyboard-subra-wifi.dtb (for the i.MX 6 DualLite) into the TFTP server root directory. Then flash the kernel and rootfs as described in section "Updating NAND Flash from Network". After that erase the oftree partition with:
bootloader$ erase /dev/nand0.oftree.bb
- Then flash the device tree:
bootloader$ cp -v /mnt/tftp/zImage-imx6dl-phytec-phyboard-subra-wifi.dtb /dev/nand0.oftree.bb
- Now, boot the board from NAND.
bootloader$ boot nand
| |
On the phyBOARD-Subra the Wi-Fi expansion board (PEB-B-001) cannot be used with the SD card interface at the same time. You have to boot from NAND Flash. For the correct orientation of the expansion board consult the corresponding hardware manual. |
To enable the Wi-Fi expansion board on the phyBOARD-Mira, perform the following steps:
- Start the board and stop in the bootloader shell.
- Then edit the file /env/config-expansion with:
bootloader$ edit /env/config-expansions
- In the file remove the '#' character in the line:
. /env/expansions/imx6qdl-phytec-peb-wlbt-01
- After that press CTRL+D and save the environment with:
bootloader$ saveenv
- Now, reboot the board.
bootloader$ boot
| |
To use the expansion board PEB-WLBT-01 on the phyBOARD-Mira hardware modifications are required. These are implemented on the phyBOARD-Mira with article number PB-01501-1201I. |
After enabling the Wi-Fi module on the expansion board and booting the kernel, you should see an output on your console similar to the following:
cfg80211: Calling CRDA to update world regulatory domain wlcore: loaded wlcore: firmware booted (Rev 6.3.10.0.133)
Calibration
Calibration is a process of determining radio parameters for a specific chip. These configuration parameters are suitable to the specific chip with its unique design. Therefore, the calibration parameters are sent back to the driver to be stored in non-volatile memory for later use. Upon initialization, the wL12xx driver loads an nvs file, where it expects to read those calibration parameters to send them to the chip. The nvs file includes two main parts: one stores the calibration parameters and the other stores the initialization information required for the wL12xx driver. The calibration is described also in
http://processors.wiki.ti.com/index.php/WL12xx_NLCP_Calibration_Process and http://linuxwireless.org/en/users/Drivers/wl12xx/calibrator/#wl12xx_Calibration.
TI provides a calibration tool which can be found in the 18xx-ti-utils repository:
git://git.ti.com/wilink8-wlan/18xx-ti-utils.git
The calibrator version used is 0.80.
- Before starting the calibration, the WiFi module has to be set to PLT mode. For this purpose open the menuconfig in your Yocto directory:
<yocto_dir>/build$ bitbake virtual/kernel -c menuconfig
- Activate the NL80211_TESTMODE configuration:
Networking support > Wireless > nl80211 testmode command
- Press F6 to save the configurations and F9 to leave. Rebuild the kernel
<yocto_dir>/build$ bitbake phytec-headless-image
- Flash the new BSP image to the board (section "Updating the Software") and reboot the module.
- To start the calibration first generate an nvs reference file:
target$ calibrator set ref_nvs /usr/share/wl127x-inis/tiwi-ble-fcc-etsi.ini target$ cp new-nvs.bin /lib/firmware/ti-connectivity/wl1271-nvs.bin
- Reload the driver:
target$ ifconfig wlan0 down target$ rmmod wlcore_sdio target$ modprobe wlcore_sdio
- Now perform the first calibration:
target$ calibrator plt calibrate
- Copy the newly created file to the proper location:
target$ cp new-nvs.bin /lib/firmware/ti-connectivity/wl1271-nvs.bin
- Finally set the WLAN MAC address:
target$ calibrator set nvs_mac /lib/firmware/ti-connectivity/wl1271-nvs.bin 00:00:00:00:00:00
- Restart the module to get the new MAC address:
target$ rmmod wlcore_sdio target$ modprobe wlcore_sdio
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Remove the NL80211_TESTMODE config before shipping the BSP |
Customizing the BSP
Changing MTD Partitions
For Memory Technology Devices (MTD) like NAND Flash or SPI NOR Flash the partitions are usually defined in the device trees, i.e. they are defined in the device tree of the MLO, the barebox and the kernel. When changing the partition table all those parts need to be touched. Newer barebox versions (v2015.07.0 and newer) have a mechanism to overwrite partitions at runtime.
The barebox holds an internal list with partitions which are initialized with the partition table out of the barebox device tree. This list is used later on to fix up the device tree of the kernel and can be overwritten in the barebox shell, or with a script before booting the kernel.
- To print the partitions just type:
bootloader$ echo $<mtddevice>.partitions
Example:
bootloader$ echo $nand0.partitions 4M(barebox),1M(barebox-environment),1M(oftree),8M(kernel),1010M(root)
- To overwrite the partitions just change the partitions variable:
bootloader$ m25p0.partitions=1M(barebox),128k(barebox-environment),128k(oftree),5104k(kernel)
Adding and deleting partitions by overwriting the partitions variable is possible. But do not touch the barebox and bareboxenv partitions. Those should not be changed at runtime.
