i.MX8MP EVK

Overview

i.MX8M Plus LPDDR4 EVK board is based on NXP i.MX8M Plus applications processor, composed of a quad Cortex®-A53 cluster and a single Cortex®-M7 core. Zephyr OS is ported to run on the Cortex®-A53 core.

Board features:
- RAM: 2GB LPDDR4
- Storage:
  - SanDisk 16GB eMMC5.1
  - Micron 32MB QSPI NOR
  - microSD Socket
- Wireless:
  - WiFi: 2.4/5GHz IEEE 802.11b/g/n
  - Bluetooth: v4.1
- USB:
  - OTG - 2x type C
- Ethernet
- PCI-E M.2
- Connectors:
  - 40-Pin Dual Row Header
- LEDs:
  - 1x Power status LED
  - 1x UART LED
- Debug
  - JTAG 20-pin connector
  - MicroUSB for UART debug, two COM ports for A53 and M4

More information about the board can be found at the NXP website.

Supported Features

The Zephyr mimx8mp_evk_a53 board configuration supports the following hardware features:

Interface	Controller	Driver/Component
GIC-v3	on-chip	interrupt controller
ARM TIMER	on-chip	system clock
CLOCK	on-chip	clock_control
PINMUX	on-chip	pinmux
RDC	on-chip	Resource Domain Controller
UART	on-chip	serial port
ENET	on-chip	ethernet port

The Zephyr mimx8mp_evk_m7 board configuration supports the following hardware features:

Interface	Controller	Driver/Component
NVIC	on-chip	nested vector interrupt controller
SYSTICK	on-chip	systick
CLOCK	on-chip	clock_control
PINMUX	on-chip	pinmux
UART	on-chip	serial port-polling; serial port-interrupt

Devices

System Clock

This board configuration uses a system clock frequency of 8 MHz.

The M7 Core is configured to run at a 800 MHz clock speed.

Serial Port

This board configuration uses a single serial communication channel with the CPU’s UART4.

Programming and Debugging (A53)

U-Boot “cpu” command is used to load and kick Zephyr to Cortex-A secondary Core, Currently it is supported in : Real-Time Edge U-Boot (use the branch “uboot_vxxxx.xx-y.y.y, xxxx.xx is uboot version and y.y.y is Real-Time Edge Software version, for example “uboot_v2023.04-2.9.0” branch is U-Boot v2023.04 used in Real-Time Edge Software release v2.9.0), and pre-build images and user guide can be found at Real-Time Edge Software.

Copy the compiled zephyr.bin to the first FAT partition of the SD card and plug the SD card into the board. Power it up and stop the u-boot execution at prompt.

Use U-Boot to load and kick zephyr.bin to Cortex-A53 Core0:

fatload mmc 1:1 0xc0000000 zephyr.bin; dcache flush; icache flush; go 0xc0000000

Or kick zephyr.bin to the other Cortex-A53 Core, for example Core2:

fatload mmc 1:1 0xc0000000 zephyr.bin; dcache flush; icache flush; cpu 2 release 0xc0000000

Use this configuration to run basic Zephyr applications and kernel tests, for example, with the Basic Synchronization sample:

# From the root of the zephyr repository
west build -b imx8mp_evk/mimx8ml8/a53 samples/synchronization
west build -t run

This will build an image with the synchronization sample app, boot it and display the following console output:

*** Booting Zephyr OS build zephyr-v3.1.0-3575-g44dd713bd883  ***
thread_a: Hello World from cpu 0 on mimx8mp_evk_a53!
thread_b: Hello World from cpu 0 on mimx8mp_evk_a53!
thread_a: Hello World from cpu 0 on mimx8mp_evk_a53!
thread_b: Hello World from cpu 0 on mimx8mp_evk_a53!
thread_a: Hello World from cpu 0 on mimx8mp_evk_a53!

Use Jailhouse hypervisor, after root cell linux is up:

#jailhouse enable imx8mp.cell
#jailhouse cell create imx8mp-zephyr.cell
#jailhouse cell load 1 zephyr.bin -a 0xc0000000
#jailhouse cell start 1

Programming and Debugging (M7)

The MIMX8MP EVK board doesn’t have QSPI flash for the M7, and it needs to be started by the A53 core. The A53 core is responsible to load the M7 binary application into the RAM, put the M7 in reset, set the M7 Program Counter and Stack Pointer, and get the M7 out of reset. The A53 can perform these steps at bootloader level or after the Linux system has booted.

The M7 can use up to 3 different RAMs (currently, only two configurations are supported: ITCM and DDR). These are the memory mapping for A53 and M7:

Region	Cortex-A53	Cortex-M7 (System Bus)	Cortex-M7 (Code Bus)	Size
OCRAM	0x00900000-0x0098FFFF	0x20200000-0x2028FFFF	0x00900000-0x0098FFFF	576KB
DTCM	0x00800000-0x0081FFFF	0x20000000-0x2001FFFF		128KB
ITCM	0x007E0000-0x007FFFFF		0x00000000-0x0001FFFF	128KB
OCRAM_S	0x00180000-0x00188FFF	0x20180000-0x20188FFF	0x00180000-0x00188FFF	36KB
DDR	0x80000000-0x803FFFFF	0x80200000-0x803FFFFF	0x80000000-0x801FFFFF	2MB

For more information about memory mapping see the i.MX 8M Applications Processor Reference Manual (section 2.1 to 2.3)

At compilation time you have to choose which RAM will be used. This configuration is done based on board name (imx8mp_evk/mimx8ml8/m7 for ITCM and imx8mp_evk/mimx8ml8/m7/ddr for DDR).

There are two methods to load M7 Core images: U-Boot command and Linux remoteproc.

Load and Run M7 Zephyr Image from U-Boot

Load and run Zephyr on M7 from A53 using u-boot by copying the compiled zephyr.bin to the first FAT partition of the SD card and plug the SD card into the board. Power it up and stop the u-boot execution at prompt.

Load the M7 binary onto the desired memory and start its execution using:

ITCM

fatload mmc 0:1 0x48000000 zephyr.bin
cp.b 0x48000000 0x7e0000 20000
bootaux 0x7e0000

DDR

fatload mmc 0:1 0x80000000 zephyr.bin
dcache flush
bootaux 0x80000000

Load and Run M7 Zephyr Image by using Linux remoteproc

Prepare device tree:

The device tree must inlcude CM7 dts node with compatible string “fsl,imx8mn-cm7”, and also need to reserve M4 DDR memory if using DDR code and sys address, and also need to put “m4_reserved” in the list of memory-region property of the cm7 node.

reserved-memory {
         #address-cells = <2>;
         #size-cells = <2>;
         ranges;

         m7_reserved: m4@80000000 {
               no-map;
               reg = <0 0x80000000 0 0x1000000>;
         };
         ...
}


imx8mp-cm7 {
         compatible = "fsl,imx8mn-cm7";
         rsc-da = <0x55000000>;
         clocks = <&clk IMX8MP_CLK_M7_DIV>,
                  <&audio_blk_ctrl IMX8MP_CLK_AUDIO_BLK_CTRL_AUDPLL_ROOT>;
         clock-names = "core", "audio";
         mbox-names = "tx", "rx", "rxdb";
         mboxes = <&mu 0 1
                  &mu 1 1
                  &mu 3 1>;
         memory-region = <&vdevbuffer>, <&vdev0vring0>, <&vdev0vring1>, <&rsc_table>, <&m7_reserved>;
         status = "okay";
         fsl,startup-delay-ms = <500>;
};

Extra Zephyr Kernel configure item for DDR Image:

If use remotepoc to boot DDR board (imx8mp_evk/mimx8ml8/m7/ddr), also need to enable “CONFIG_ROMSTART_RELOCATION_ROM” in order to put romstart memory section into ITCM because M7 Core will get the first instruction from zero address of ITCM, but romstart relocation will make the storage size of zephyr.bin too large, so we don’t enable it by default in board defconfig.

diff --git a/boards/nxp/imx8mp_evk/imx8mp_evk_mimx8ml8_m7_ddr_defconfig b/boards/nxp/imx8mp_evk/imx8mp_evk_mimx8ml8_m7_ddr_defconfig
index 17542cb4eec..8c30c5b6fa3 100644
--- a/boards/nxp/imx8mp_evk/imx8mp_evk_mimx8ml8_m7_ddr_defconfig
+++ b/boards/nxp/imx8mp_evk/imx8mp_evk_mimx8ml8_m7_ddr_defconfig
@@ -12,3 +12,4 @@ CONFIG_CONSOLE=y
CONFIG_XIP=y
CONFIG_CODE_DDR=y
+CONFIG_ROMSTART_RELOCATION_ROM=y

Then use the following steps to boot Zephyr kernel:

In U-Boot command line execute prepare script:

u-boot=> run prepare_mcore

Boot Linux kernel with specified dtb and then boot Zephyr by using remoteproc:

root@imx8mp-lpddr4-evk:~# echo zephyr.elf > /sys/devices/platform/imx8mp-cm7/remoteproc/remoteproc0/firmware
root@imx8mp-lpddr4-evk:~# echo start  > /sys/devices/platform/imx8mp-cm7/remoteproc/remoteproc0/state
[   39.195651] remoteproc remoteproc0: powering up imx-rproc
[   39.203345] remoteproc remoteproc0: Booting fw image zephyr.elf, size 503992
[   39.203388] remoteproc remoteproc0: No resource table in elf
root@imx8mp-lpddr4-evk:~# [   39.711380] remoteproc remoteproc0: remote processor imx-rproc is now up

root@imx8mp-lpddr4-evk:~#

Debugging

MIMX8MP EVK board can be debugged by connecting an external JLink JTAG debugger to the J24 debug connector and to the PC. Then the application can be debugged using the usual way.

Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b imx8mp_evk/mimx8ml8/m7 samples/hello_world
west debug

Open a serial terminal, step through the application in your debugger, and you should see the following message in the terminal:

*** Booting Zephyr OS build v2.7.99-1310-g2801bf644a91  ***
Hello World! imx8mp_evk