RPMSG on a Toradex Apalis iMX8

Technical Support
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1

Dear Toradex Community,
I am building an application with a Apalis iMX8 on which both the M4Fs communicate with a separate CAN Bus to our product. On those I use FreeRTOS and they communicate with each other using the Message Unit.

Now I would like to also broadcast the received CAN Data from both of the M4Fs to the Linux-System. For this purpose I try to use RPMSG.

I tried to follow the readme.txt in the rpmsg_lite_str_echo_rtos example in the multicore folder of the SDK from NXP and your page Communicating between cores with RPMsg .

My problem now is that the RPMSG never appears as a TTY.

Until now I did the following steps:

  • In the device Tree File imx8qm.dsti i changed the status of both rpmsg0 and rpmsg1 to "okay", then i compiled and uploaded the device tree using TCBuilder
  • Then: modprobe imx_rpmsg_tty
  • finally: echo imx_rpmsg_tty > /etc/modules-load.d/rpmsg_tty.conf

The problem now is i never see a TTY in /dev and when inspecting dmesg i get several errors like this: virtio_rpmsg_bus: probe of virtio0 failed with error -12
Do you have any suggestions on how to deal with RPMSG using Torizon? Thank you in advance!
2

Hi @Juli7478,

I made this overlay works on BSP 6.3. Could you please check if it looks like yours or test it on TorizonCore 6 as well? It should work. This will enable the RPMsg channels and then, after the modprobe, you should see the tty devices appears in your module.

/dts-v1/;
/plugin/;

/ {
	compatible = "toradex,apalis-imx8-v1.1",
		     "toradex,apalis-imx8",
		     "fsl,imx8qm";
};

&{/} {
	reserved-memory {

		#address-cells = <2>;
		#size-cells = <2>;
		ranges;

		vdev0vring0: vdev0vring0@90000000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90000000 0 0x8000>;
			no-map;
		};

		vdev0vring1: vdev0vring1@90008000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90008000 0 0x8000>;
			no-map;
		};

		vdev1vring0: vdev1vring0@90010000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90010000 0 0x8000>;
			no-map;
		};

		vdev1vring1: vdev1vring1@90018000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90018000 0 0x8000>;
			no-map;
		};

		vdev2vring0: vdev0vring0@90100000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90100000 0 0x8000>;
			no-map;
		};

		vdev2vring1: vdev0vring1@90108000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90108000 0 0x8000>;
			no-map;
		};

		vdev3vring0: vdev1vring0@90110000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90110000 0 0x8000>;
			no-map;
		};

		vdev3vring1: vdev1vring1@90118000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90118000 0 0x8000>;
			no-map;
		};

		vdevbuffer: vdevbuffer {
                        compatible = "shared-dma-pool";
			reg = <0 0x90400000 0 0x100000>;
			no-map;
		};
	};

	rpmsg0: rpmsg@0 {
		compatible = "fsl,imx8qm-rpmsg";
		mbox-names = "tx", "rx", "rxdb";
		mboxes = <&lsio_mu5 0 1
			  &lsio_mu5 1 1
			  &lsio_mu5 3 1>;
		mub-partition = <3>;
		vdev-nums = <2>;
		reg = <0 0x90000000 0 0x20000>;
		memory-region = <&vdevbuffer>, <&vdev0vring0>, <&vdev0vring1>,
				<&vdev1vring0>, <&vdev1vring1>;
		status = "okay";
	};

	rpmsg1: rpmsg1 {
		compatible = "fsl,imx8qm-rpmsg";
		mbox-names = "tx", "rx", "rxdb";
		mboxes = <&lsio_mu6 0 1
			  &lsio_mu6 1 1
			  &lsio_mu6 3 1>;
		mub-partition = <4>;
		vdev-nums = <2>;
		reg = <0 0x90100000 0 0x20000>;
		memory-region = <&vdevbuffer>, <&vdev2vring0>, <&vdev2vring1>,
				<&vdev3vring0>, <&vdev3vring1>;
		status = "okay";
	};
};

&iomuxc {
	pinctrl-0 = <&pinctrl_cam1_gpios>, <&pinctrl_dap1_gpios>,
		    <&pinctrl_esai0_gpios>, <&pinctrl_fec2_gpios>,
		    <&pinctrl_gpio3>, <&pinctrl_gpio4>, <&pinctrl_gpio_keys>,
		    <&pinctrl_gpio_usbh_oc_n>,
		    <&pinctrl_lvds0_i2c0_gpio>, <&pinctrl_lvds1_i2c0_gpios>,
		    <&pinctrl_mipi_dsi_0_1_en>, <&pinctrl_mipi_dsi1_gpios>,
		    <&pinctrl_mlb_gpios>, <&pinctrl_qspi1a_gpios>,
		    <&pinctrl_sata1_act>, <&pinctrl_sim0_gpios>,
		    <&pinctrl_usdhc1_gpios>;
};

&lpuart2 {
	status = "disabled";
};

&lsio_pwm0 {
	status = "disabled";
};

&lsio_pwm1 {
	status = "disabled";
};

Best Regards,
Hiago.

3

Dear @hfranco.tx ,
Thanks for your answer.
Specifically I am using TorizonCore 5.7.0 build 17. and not TC6

I tried to apply your Overlay as is, but the disabling of &lsio_pwm0 and &lsio_pwm1 result in the error Failed to apply '/tmp/tmptfa45zdx': FDT_ERR_NOTFOUND .
Thus, I replaced the groupnames with &pwm0 and &pwm1. Like this I can build the devicetree. However, I don’t know if this has any imapct on RPMSG.

Now I applied the adapted Overlay and the virtio error does not appear anymore. In dmesg i get these lines, which looks promising:

[    2.359908] virtio_rpmsg_bus virtio0: rpmsg host is online
[    2.389929] virtio_rpmsg_bus virtio1: rpmsg host is online
[    2.390339] imx-rpmsg 90100000.rpmsg1: assigned reserved memory node vdevbuffer
[    2.419917] virtio_rpmsg_bus virtio2: rpmsg host is online
[    2.449923] virtio_rpmsg_bus virtio3: rpmsg host is online

Nevertheless, the RPMSG TTY still does not appear in /dev. After the modprobe, I checked using lsmod and i get this line, which indicate that it is not used by anything:

imx_rpmsg_tty          20480  0

Do you have any further suggestions?
Sincerely

4

Hi @Juli7478,

I’m sorry for the delay.

For TorizonCore 5 or BSP 5, can you please try the following code?

/dts-v1/;
/plugin/;

#include <dt-bindings/firmware/imx/rsrc.h>

/* Enable RPMSG for Apalis iMX8 */

/ {
	compatible = "toradex,apalis-imx8-v1.1",
		     "toradex,apalis-imx8",
		     "fsl,imx8qm";
};


&{/} {

    reserved-memory {

		#address-cells = <2>;
		#size-cells = <2>;
		ranges;

        /* Allocate TX and RX buffers for communication between m4 cores
        with Linux and m4 core0 with m4 core1. Allocate the necessary resource
        tables as well. */
        
        vdev0vring0: vdev0vring0@90000000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90000000 0 0x8000>;
			no-map;
		};

		vdev0vring1: vdev0vring1@90008000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90008000 0 0x8000>;
			no-map;
		};

		vdev1vring0: vdev1vring0@90010000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90010000 0 0x8000>;
			no-map;
		};

		vdev1vring1: vdev1vring1@90018000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90018000 0 0x8000>;
			no-map;
		};

        rsc_table0: rsc_table0@0x900ff000 {
			reg = <0 0x900ff000 0 0x1000>;
			no-map;
		};
		
        rsc_table1: rsc_table1@0x901ff000 {
			reg = <0 0x901ff000 0 0x1000>;
			no-map;
		};

        vdev2vring0: vdev0vring0@90100000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90100000 0 0x8000>;
			no-map;
		};

		vdev2vring1: vdev0vring1@90108000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90108000 0 0x8000>;
			no-map;
		};

		vdev3vring0: vdev1vring0@90110000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90110000 0 0x8000>;
			no-map;
		};

		vdev3vring1: vdev1vring1@90118000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90118000 0 0x8000>;
			no-map;
		};
    };
};

&rpmsg0 {
    status = "okay";
};

&rpmsg1 {
    status = "okay";
};

It should be possible to compile and use it with TorizonCore 5 and the rpmsg will be enabled. Can you please check on your side and see if it works?

Best Regards,
Hiago.

5

Hi @hfranco.tx ,
Thanks for the suggestion. I tried your overlay, but the TTY still does not seem to appear. In dmesg I get exactly the same lines as previously.
Maybe I am overseeing it in /dev, as I am not sure whats the actual name of it. How exactly should it appear?

I am also not sure if this is related, and if it is even new, but i get the following Error while booting:

## Flattened Device Tree blob at 83000000
   Booting using the fdt blob at 0x83000000
   Loading Ramdisk to fcd8c000, end fd64d32f ... OK
ERROR: reserving fdt memory region failed (addr=95000000 size=400000)
   Loading Device Tree to 00000000fcd3f000, end 00000000fcd8bfff ... OK

Another question: Does the RPMSG on the M4 side has to be active for it to appear in /dev? And am I right, that the RPMSGLite Library on the M4 side is compatible with the normal RPMSG Protocol on the Linux side, as long as the memory area is correctly specified?

Many Thanks!!

6

Hi @Juli7478,

I tested the overlay on my side with TorizonCore 5 and it worked for me. Could you please double-check how you’re loading it?

If you want to try mine, here is the DTBO file (it’s going to be available for 3 months): Download - Toradex File Sharing Platform

Here I copied this file to /boot/ostree/<hash>/dtb/overlays and then edited the /boot/ostree/<hash>/dtb/overlays.txt file to include the name of this overlay, apalis-imx8_hmp_overlay.dtbo.

Next, I’ve compiled and loaded the M4 binary called rpmsg_lite_str_echo_rtos_m40.bin inside the multicore example folder.

For more information on how to load your binary, please check these guides:

After rebooting and M4 successfully running, I can see these messages on dmesg:

torizon@apalis-imx8-07204567:~$ dmesg | grep rpmsg
[    0.082549] imx rpmsg driver is registered.
[    2.392342] imx-rpmsg 90000000.rpmsg0: assigned reserved memory node vdevbuffer
[    2.392820] virtio_rpmsg_bus virtio0: rpmsg host is online
[    2.393239] virtio_rpmsg_bus virtio1: rpmsg host is online
[    2.393429] virtio_rpmsg_bus virtio1: creating channel rpmsg-virtual-tty-channel addr 0x1e
[    2.393565] imx-rpmsg 90100000.rpmsg1: assigned reserved memory node vdevbuffer
[    2.422026] virtio_rpmsg_bus virtio2: rpmsg host is online
[    2.452446] virtio_rpmsg_bus virtio3: rpmsg host is online

After loading the driver, I can see the channel has been created and I can send messages and check the echo back:

torizon@apalis-imx8-07204567:~$ sudo modprobe imx_rpmsg_tty
Password: 
torizon@apalis-imx8-07204567:~$ dmesg | grep rpmsg
[    0.082549] imx rpmsg driver is registered.
[    2.392342] imx-rpmsg 90000000.rpmsg0: assigned reserved memory node vdevbuffer
[    2.392820] virtio_rpmsg_bus virtio0: rpmsg host is online
[    2.393239] virtio_rpmsg_bus virtio1: rpmsg host is online
[    2.393429] virtio_rpmsg_bus virtio1: creating channel rpmsg-virtual-tty-channel addr 0x1e
[    2.393565] imx-rpmsg 90100000.rpmsg1: assigned reserved memory node vdevbuffer
[    2.422026] virtio_rpmsg_bus virtio2: rpmsg host is online
[    2.452446] virtio_rpmsg_bus virtio3: rpmsg host is online
[   80.633880] imx_rpmsg_tty virtio1.rpmsg-virtual-tty-channel.-1.30: new channel: 0x400 -> 0x1e!
[   80.634086] Install rpmsg tty driver!
torizon@apalis-imx8-07204567:~$ ls /dev/ | grep -i rpmsg
ttyRPMSG30
torizon@apalis-imx8-07204567:~$ cat /dev/ttyRPMSG30 &
[1] 1500
torizon@apalis-imx8-07204567:~$ echo Toradex > /dev/ttyRPMSG30 
torizon@apalis-imx8-07204567:~$ Toradex

Toradex

Let me know if you have any questions or need help.

Best Regards,
Hiago.

7

Dear @hfranco.tx
Many thanks for the support, I successfully loaded the M4 Image and now get the same behavior as yours. I think the problem was, that the M4 Program was not running previously.
Best regards,
Julian

1 Like
8

Hi @hfranco.tx ,
I am using BSP 5.7.6 and have followed the device tree you suggested as follows:

/dts-v1/;
/plugin/;

#include <dt-bindings/firmware/imx/rsrc.h>

/* Disable PWM0 and PMW1 to use M4 Core 1 UART */

/ {
    compatible = "toradex,apalis-imx8qm-ixora-v1.2",
		 "toradex,apalis-imx8-ixora-v1.2",
		 "toradex,apalis-imx8qm-ixora",
		 "toradex,apalis-imx8-ixora",
		 "toradex,apalis-imx8qm",
		 "toradex,apalis-imx8-v1.1",
		 "toradex,apalis-imx8",
		 "fsl,imx8qm";
		
};

&{/} {

    reserved-memory {

		#address-cells = <2>;
		#size-cells = <2>;
		ranges;

		/* Allocate TX and RX buffers for communication between m4 cores
		with Linux and m4 core0 with m4 core1. Allocate the necessary resource
		tables as well. */
		
		vdev0vring0: vdev0vring0@90000000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90000000 0 0x8000>;
			no-map;
		};

		vdev0vring1: vdev0vring1@90008000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90008000 0 0x8000>;
			no-map;
		};

		vdev1vring0: vdev1vring0@90010000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90010000 0 0x8000>;
			no-map;
		};

		vdev1vring1: vdev1vring1@90018000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90018000 0 0x8000>;
			no-map;
		};

        	rsc_table0: rsc_table0@0x900ff000 {
			reg = <0 0x900ff000 0 0x1000>;
			no-map;
		};
		
        	rsc_table1: rsc_table1@0x901ff000 {
			reg = <0 0x901ff000 0 0x1000>;
			no-map;
		};

        	vdev2vring0: vdev0vring0@90100000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90100000 0 0x8000>;
			no-map;
		};

		vdev2vring1: vdev0vring1@90108000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90108000 0 0x8000>;
			no-map;
		};

		vdev3vring0: vdev1vring0@90110000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90110000 0 0x8000>;
			no-map;
		};

		vdev3vring1: vdev1vring1@90118000 {
			compatible = "shared-dma-pool";
			reg = <0 0x90118000 0 0x8000>;
			no-map;
		};
    };
};

&pwm0 {
    status = "disabled";
};

&pwm1 {
    status = "disabled";
};

&lpuart2 {
    status = "disabled";
};

&rpmsg0{
	status = "okay";
};

&rpmsg1{
	status = "okay";
};

and it works to start rpmsg on boot and it also runs on the M4_1 core I’m using with rpmsg_lite_str_echo_rtos_m41.bin.

[    0.090626] 001: imx rpmsg driver is registered.
[    3.392638] 004: imx-rpmsg 90000000.rpmsg0: assigned reserved memory node vdevbuffer
[    3.393432] 004: virtio_rpmsg_bus virtio0: Registered as RPMsg char device.
[    3.415331] 004: virtio_rpmsg_bus virtio0: rpmsg host is online
[    3.415856] 004: virtio_rpmsg_bus virtio1: Registered as RPMsg char device.
[    3.439356] 004: virtio_rpmsg_bus virtio1: rpmsg host is online
[    3.439777] 004: imx-rpmsg 90100000.rpmsg1: assigned reserved memory node vdevbuffer
[    3.440563] 004: virtio_rpmsg_bus virtio2: Registered as RPMsg char device.
[    3.440649] 004: virtio_rpmsg_bus virtio2: rpmsg host is online
[    3.441408] 004: virtio_rpmsg_bus virtio3: Registered as RPMsg char device.
[    3.441436] 004: virtio_rpmsg_bus virtio3: rpmsg host is online
[    3.441482] 000: virtio_rpmsg_bus virtio3: creating channel rpmsg-virtual-tty-channel-1 addr 0x1f
[    3.441538] 000: virtio_rpmsg_bus virtio3: Remote has announced service rpmsg-virtual-tty-channel-1, 31.
[    3.442160] 000: virtio_rpmsg_bus virtio2: creating channel rpmsg-i2c-channel addr 0x1
[    3.442184] 000: virtio_rpmsg_bus virtio2: Remote has announced service rpmsg-i2c-channel, 1.

image

but my problem is how to enable tty rpmsg on /dev because after I load the imx_rpmsg_tty module there is no output and on /dev there is no ttyRPMSG…

image
image

so what have i not done yet to be able to achieve the same situation as you did because i think the problem in the linux kernel config that is related to the rpmsg has been activated. please give me a clue or suggestion.

root@apalis-imx8-14904109:~# zcat /proc/config.gz |grep -i "rpmsg"
CONFIG_GPIO_IMX_RPMSG=y
CONFIG_REGULATOR_PF1550_RPMSG=y
CONFIG_SND_SOC_FSL_RPMSG_I2S=y
CONFIG_SND_SOC_IMX_PCM_RPMSG=y
CONFIG_SND_SOC_IMX_I2S_RPMSG=y
CONFIG_SND_SOC_IMX_RPMSG=y
CONFIG_SND_SOC_RPMSG_WM8960=y
CONFIG_SND_SOC_RPMSG_WM8960_I2C=y
CONFIG_SND_SOC_RPMSG_CS42XX8=y
CONFIG_SND_SOC_RPMSG_AK4497=y
# CONFIG_RTC_DRV_IMX_RPMSG is not set
# Rpmsg drivers
CONFIG_RPMSG=y
CONFIG_RPMSG_CHAR=y
CONFIG_RPMSG_QCOM_GLINK_NATIVE=y
CONFIG_RPMSG_QCOM_GLINK_RPM=y
CONFIG_RPMSG_VIRTIO=y
CONFIG_RPMSG_VIRTIO_CHAR=y
CONFIG_HAVE_IMX_RPMSG=y
CONFIG_IMX_RPMSG_PINGPONG=m
CONFIG_IMX_RPMSG_TTY=m
# end of Rpmsg drivers

Best regards,
Azka.

9

Hi @Azkaaa , please try the patch provided here.