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RPMsg.md

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RPMsg

This document explains how to run TI's lab_5 (and similarly any other RPMsg firmware example) on the BBB, without using the Code Composer Studio. This method is working as of 26-06-2019. RPMsg is a little tricky to get started with so I recommend following these steps. These are the exhaustive steps in using RPMsgs:

  1. SSH into the BeagleBone Black.
  2. Some tasks need you to be the root user, so login as root or use sudo if you get permission denied error.
  3. $ uname -r to verify kernel -> mine at the moment is 4.14.71-ti-r80
    Debian Version: BeagleBoard.org Debian Image 2018-10-07 (use $ cat /etc/issue to find)
  4. $ sudo apt-get update.
  5. cd / and then find clpru compiler which is generally in /usr/share/ti/cgt-pru. This is the location of the PRU code generation tools - compiler.
  6. On doing this:
$ which clpru
/usr/bin/clpru

So the compiler binary is in a different location. This is a problem for labs to make files.

$ cd /usr/share/ti/cgt-pru
$ mkdir bin
$ ln -s /usr/bin/clpru clpru

So now the make files will find the compiler executable in the correct location via the symbolic link.

ARM Linux also needs to create a symbolic link to the /usr/bin/ directory in order to use the same Makefile (ARM Linux) ln -s /usr/bin/ /usr/share/ti/cgt-pru/bin - I'm not entirely sure about this but I'll check on a different image and update.

  1. Make sure all the modules are loaded.
$ sudo modprobe pru_rproc
$ sudo modprobe rpmsg_pru
$ sudo modprobe virtio_rpmsg_bus
  1. $ cd ~
    $ git clone git://git.ti.com/pru-software-support-package/pru-software-support-package.git
    This will clone a copy of the latest pru-software-support-package: The ones used in TI's Hands On Training Labs.
  2. cd into lab_5 in the package:
$ cd lab_5/solution/PRU_Halt
$ make

This will fail, it is looking for the environment variable $PRU_CGT
$ export PRU_CGT=/usr/share/ti/cgt-pru
Now try make again. It should succeed.

  1. Do (for pru0)
$ cd gen
$ sudo cp PRU_Halt.out am335x-pru0-fw
$ sudo cp am335x-pru0-fw /lib/firmware
  1. Now cd into the PRU_RPMsg_Echo_Interrupt1 directory in the same lab_5.
    Edit main.c as follows:
//#define CHAN_NAME                 "rpmsg-client-sample"
#define CHAN_NAME                   "rpmsg-pru"

(Comment, Uncomment)

  1. Now almost the same as #10, this time for pru1:
$ cd gen
$ cp PRU_RPMsg_Echo_Interrupt1.out am335x-pru1-fw
$ cp am335x-pru1-fw /lib/firmware

  1. (i)REBOOT THE BBB (sudo reboot), This is important otherwise you will get state not found error; (ii) Start the second PRU i.e. pru1 - $ echo start | sudo tee /sys/class/remoteproc/remoteproc2/state

  2. cd /dev look for rpmsg_pru31 device file. It will be there!

  3. $ dmesg or $ dmesg | grep pru - The last few lines of dmesg should be something like this:

[   76.778231] pruss 4a300000.pruss: creating PRU cores and other child platform devices
[   76.811666] remoteproc remoteproc1: 4a334000.pru is available
[   76.811792] pru-rproc 4a334000.pru: PRU rproc node /ocp/pruss_soc_bus@4a326004/pruss@0/pru@34000 probed successfully
[   76.813392] remoteproc remoteproc2: 4a338000.pru is available
[   76.813498] pru-rproc 4a338000.pru: PRU rproc node /ocp/pruss_soc_bus@4a326004/pruss@0/pru@38000 probed successfully
[ 2035.360460] remoteproc remoteproc2: powering up 4a338000.pru
[ 2035.371491] remoteproc remoteproc2: Booting fw image am335x-pru1-fw, size 74032
[ 2035.374631] pruss 4a300000.pruss: configured system_events[63-0] = 0x00000000.000c0000
[ 2035.374652] pruss 4a300000.pruss: configured intr_channels = 0x0000000a host_intr = 0x0000000a
[ 2035.383501] virtio_rpmsg_bus virtio0: creating channel rpmsg-pru addr 0x1f
[ 2035.384526] rpmsg_pru virtio0.rpmsg-pru.-1.31: new rpmsg_pru device: /dev/rpmsg_pru31
[ 2035.385431] virtio_rpmsg_bus virtio0: rpmsg host is online
[ 2035.385594] remoteproc remoteproc2: registered virtio0 (type 7)
[ 2035.385605] remoteproc remoteproc2: remote processor 4a338000.pru is now up

  1. Now that the firmware has been loaded and the device file is ready, we need to echo into this file and read its output to communicate with it.
    Go back to pru_software_support_package/labs/lab5

  2. Compile the rpmsg_pru_user_space_echo.c file using GCC compiler ($ g++ rpmsg_pru_user_space_echo.c).

  3. $ sudo ./a.out MAKE SURE YOU ARE THE SUPERUSER WHILE EXECUTING ./a.out OTHERWISE YOU WILL GET "Failed to open /dev/rpmsg31" ERROR

  4. You sould be able to execute the file and get "Received 100 messages, closing /dev/rpmsg31" as output.

Hopefully I did not miss any of the steps. Let me know if any changes are needed.

Additional Notes

  1. The entry remoteproc0 relates to the Wakeup M3 (CM3) remoteproc driver that helps with low power tasks on the Cortex M3 co-processor in the AM33xx family of devices-it has no role in controlling the PRU-ICSS.
  2. "main.c", line 72: error #20: identifier "RPMSG_MESSAGE_SIZE" is undefined - If you are getting this error, change the line (72 in this case) from uint8_t payload[RPMSG_MESSAGE_SIZE]; to uint8_t payload[50].

Sources:

Greg's answer: https://groups.google.com/d/msg/beagleboard/od6h9yTKUD4/jzGE6KaxAQAJ
Abhishek's answer: https://groups.google.com/d/msg/beagleboard/4P9NdglojBo/qqizuGCZAQAJ