STM32MP157——Remoteproc和RPMsg【转】

转自：https://hceng.cn/2020/05/09/STM32MP157%E2%80%94%E2%80%94Remoteproc%E5%92%8CRPMsg/

简单介绍基于STM32MP157的Remoteproc和RPMsg框架。

STM32MP1系列产品，是STM32进军Linux的首款微处理器，采用MCU+MPU的组合，集成两颗主频为650MHz的Cortex-A7应用处理器内核和一颗主频为209MHz的Cortex-M4微控制器内核。

非对称多处理Asymmetric Multiprocessing(AMP)虽然目前在嵌入式还不是主流，但未来肯定是趋势。将多媒体处理扔给专用的MCU，亦或将对控制延时敏感的传感器交给MCU实时控制，更多的组合给人更多的遐想。

对于非对称多核架构，不同的核心是如何启动运行，又是如何进行通信？这些疑惑在上手STM32MP157后，逐渐明朗，因此记录下笔记。

1.生成M4固件

在进行启动M4之前，需要先建立工程，生成M4固件，这里以点灯为例，简单说下创建STM32MP157的M4工程。

这里要M4点灯，涉及到资源的分配，资源分配如下图所示。

深蓝色的IP为A7独占，浅蓝色的IP为M4独占，竖线分割的IP为同一时刻只能一个占有，斜线分割的IP为任意时刻两者可以同时占用。
比如这里GPIO就为两者可以同时占用，在Linux中可以控制GPIO，同时M4也可控制GPIO。UART则为只能一个独占，分配给M4后，A7将不能控制。

支持STM32开发的集成开发环境有很多，国内熟知的有Keil MDK-ARM和IAR EWAR。这两个IDE都很好用，但它们都是商业软件，免费或评估版要么有器件型号限制，要么有程序容量限制。于是出现了免费的Eclipse+GNU GCC来搭建STM32开发环境，但搭建过程繁琐、版本差异大导致教程不统一，对新手很不友好。

STM32CubeIDE是ST公司基于Eclipse/CDT框架和GUN GCC工具链制作的免费IDE，并集成了STM32CubeMX。一个软件就可以实现STM32系列芯片的外围设备配置、代码生成、代码编辑、代码编译、在线调试，并且支持数百个Eclipse现有插件。

打开STM32CubeIDE，创建一个新的“STM32 Project”。

在弹出的STM32CubeMX，选择“STM32MP157A”，具体型号以自己使用的开发板为准。注意这里的“芯片资料区”，提供了该型号的芯片手册，不用再去网上找了。

再设置工程名字，打开STM32CubeMX的关联视图。

我使用的板子，LED灯接在PD13引脚上，因此这里把PD13设置为输出引脚。

需要注意，这里还要选中该引脚，右键弹出“Pin Reservation”，选择“Cortex-M4”，不然不会自动生成GPIO初始化代码。

最后，如图设置下GPIO的属性。

设置完后，在标签栏选择“Project”->“Generate Code”，即可自动生成相关初始化代码。默认的初始化代码如下图，需要注意的是“main.c”文件，在里面添加LED灯的控制逻辑。还有“stm32mp1xx_hal_gpio.c”，这个是hal库源码，从里面可知hal提供的GPIO相关操作函数，比如这里用到的HAL_GPIO_WritePin()。

HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_SET);
HAL_Delay(1000);
HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_RESET);
HAL_Delay(1000);

添加完LED的控制逻辑代码后，在标签栏选择“Project”->“Build Project”即可编译工程，得到GPIO_LED_CM4.elf。该文件就是M4的固件，包含Cortex-A7和Cortex-M4都可以访问的资源表(.resource_table)和LED的控制程序等。

在Linux里，使用readelf -a GPIO_LED_CM4.elf命令，可以获取ELF文件的更多信息。

2.Remoteproc框架

Remoteproc(Remote Processor Framework)，主要作用就是对远程处理器的生命周期进行管理，即启动、停止远程处理器。
以STM32MP157为例，Cortex-A内核先启动，然后使用Linux RemoteProc框架进行加载Cortex-M4固件，启动M4内核。

ST官方提供的内核已经默认配置了Remoteproc驱动，进入系统后，首先将要运行的M4固件放在/lib/firmware/目录下，然后将固件名字写到/sys/class/remoteproc/remoteproc0/firmware，再操作/sys/class/remoteproc/remoteproc0/state启动、停止M4处理器。

[root@stm32mp157:~]# ls /lib/firmware/
DEMO_LED_CM4.elf  
[root@stm32mp157:~]# echo GPIO_LED_CM4.elf > /sys/class/remoteproc/remoteproc0/firmware
[root@stm32mp157:~]# cat /sys/class/remoteproc/remoteproc0/state
offline
[root@stm32mp157:~]# echo start > /sys/class/remoteproc/remoteproc0/state
[22683.222322] remoteproc remoteproc0: powering up m4
[22683.229097] remoteproc remoteproc0: Booting fw image GPIO_LED_CM4.elf, size 1899976
[22683.235549] remoteproc remoteproc0: header-less resource table
[22683.241235] remoteproc remoteproc0: not resource table found for this firmware
[22683.248749] remoteproc remoteproc0: header-less resource table
[22683.254414] remoteproc remoteproc0: remote processor m4 is now up
[root@stm32mp157:~]# echo stop > /sys/class/remoteproc/remoteproc0/state
[22709.281733] remoteproc remoteproc0: warning: remote FW shutdown without ack
[22709.287325] remoteproc remoteproc0: stopped remote processor m4

除了在Linux的用户态控制M4内核的生命周期，还能在Linux内核态使用API控制(参考linux-origin_master/Documentation/remoteproc.txt)，甚至U-boot中控制。

3.RPMsg框架

Remoteproc框架实现了对远程处理器生命周期的管理，RPMsg框架(Remote Processor Messaging Framework)则是实现对远程处理器信息传递。
RPMsg是基于VirtIO的消息总线，它允许内核驱动程序与系统上可用的远程处理器进行通信，同时，驱动程序可以根据需要公开适当的用户空间接口(参考linux-origin_master/Documentation/rpmsg.txt)。

STM32MP1多核通信框架如下图。

消息服务基于共享内存，使用RPMsg和Virtio框架，RemoteProc框架则控制远程处理器生命周期。
信号通知(Mailbox)服务则基于内部IPCC(Inter-Processor communication controller)，ST提供OpenAMP相关库。

这里列举两个示例：
第一个示例在Linux的用户态和M4通信，实现A7控制M4的灯，A7和M4的相互唤醒；
第二个示例则是在Linux的内核态创建一个简单的RPMsg客户端，实现A7和M4的大量数据传输。

3.1 用户态的通信

3.1.1 A7准备

ST官方提供的内核已经默认配置了RPMSG_TTY驱动，Linux这边就不需要做什么了。
STM32MP1多核消息通信应用接口框图如下，在RPMsg和Virtio框架创建一个面向用户态的/dev/ttyRPMSG接口，M4在OpenAMP上创建虚拟串口，两者最终效果像是串口透传。

3.1.2 M4准备

创建一个STM32工程，在STM32CubeMX里，依次配置GPIO用于LED、配置UART5用于M4打印、以及配置IPCC和OPENAMP用于通信。

注意配置IPCC时，需要在NVIC Settings选项卡里，将IPCC RX1 occupied interrupt和IPCC TX1 free interrupt
的使能勾选上，不然后面的OPENAMP的Activated始终为灰色，无法激活。

生成初始化代码后，在USER CODE BEGIN 0和USER CODE END 0之间添加printf的重定向函数，让UART5与printf绑定。

/* USER CODE BEGIN 0 */
#ifdef __GNUC__
	/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
     set to 'Yes') calls __io_putchar() */
	#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
	#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */
PUTCHAR_PROTOTYPE
{
	/* Place your implementation of fputc here */
	HAL_UART_Transmit(&huart5, (uint8_t *)&ch, 1, HAL_MAX_DELAY);
	return ch;
}
/* USER CODE END 0 */

这里计划创建两个RPMsg tty通道，一个用来LED控制命令，一个用来传输唤醒命令。

1.初始化两个RPMsg tty虚拟串口

if (VIRT_UART_Init(&huart0) != VIRT_UART_OK) {
 printf("VIRT_UART_Init UART0 failed.
");
  Error_Handler();
}
 
if (VIRT_UART_Init(&huart1) != VIRT_UART_OK) {
 printf("VIRT_UART_Init UART1 failed.
");
  Error_Handler();
}

2.注册回调函数以按通道接收消息

if(VIRT_UART_RegisterCallback(&huart0, VIRT_UART_RXCPLT_CB_ID, VIRT_UART0_RxCpltCallback) != VIRT_UART_OK)
{
 Error_Handler();
}
 
if(VIRT_UART_RegisterCallback(&huart1, VIRT_UART_RXCPLT_CB_ID, VIRT_UART1_RxCpltCallback) != VIRT_UART_OK)
{
 Error_Handler();
}

3.编写虚拟串口回调函数
当RPMsg收到数据后，将调用该回调函数。在此函数里，需要将接收的数据复制到用户内存，并修改接收标志位，通知用户完成数据接收。

/* USER CODE BEGIN 4 */
void VIRT_UART0_RxCpltCallback(VIRT_UART_HandleTypeDef *huart)
{
    printf("Msg received on VIRTUAL UART0 channel:  %s 

", (char *) huart->pRxBuffPtr);
 
    /* copy received msg in a variable to sent it back to master processor in main infinite loop*/
    VirtUart0ChannelRxSize = huart->RxXferSize < MAX_BUFFER_SIZE? huart->RxXferSize : MAX_BUFFER_SIZE-1;
    memcpy(VirtUart0ChannelBuffRx, huart->pRxBuffPtr, VirtUart0ChannelRxSize);
    VirtUart0RxMsg = SET;
}
 
void VIRT_UART1_RxCpltCallback(VIRT_UART_HandleTypeDef *huart)
{
    printf("Msg received on VIRTUAL UART1 channel:  %s 

", (char *) huart->pRxBuffPtr);
 
    /* copy received msg in a variable to sent it back to master processor in main infinite loop*/
    VirtUart1ChannelRxSize = huart->RxXferSize < MAX_BUFFER_SIZE? huart->RxXferSize : MAX_BUFFER_SIZE-1;
    memcpy(VirtUart1ChannelBuffRx, huart->pRxBuffPtr, VirtUart1ChannelRxSize);
    VirtUart1RxMsg = SET;
}
/* USER CODE END 4 */

4.主函数轮询RPMsg消息
OPENAMP_check_for_message()查询MailBox状态。
当收到数据时，VIRT_UARTx_RxCpltCallback()会保存好收到数据，然后修改VirtUartxRxMsg标志位。
主函数里发现VirtUartxRxMsg标志位发生变化时，即可获取接收的数据。

while (1)
{
   OPENAMP_check_for_message();
  /* USER CODE END WHILE */
 
  /* USER CODE BEGIN 3 */
  if (VirtUart0RxMsg)
  {
    VirtUart0RxMsg = RESET;
 
    /*VirUART0收到数据*/
  }
 
  if (VirtUart1RxMsg)
  {
    VirtUart1RxMsg = RESET;
 
    /*VirUART1收到数据*/
  }
}

5.VirUART0接收控制LED指令
每次VirtUart0RxMsg发生变化，说明VirUART0收到了数据。
然后比较收到的数据内容，执行对应的操作。
这里，M4收到MSG_LED_ON(*led_on)则打开LED灯，并发送消息给A7；M4收到MSG_LED_OFF(*led_off)则关闭LED灯，并发送消息给A7。

if (VirtUart0RxMsg)
{
  VirtUart0RxMsg = RESET;
 
  if (!strncmp((char *)VirtUart0ChannelBuffRx, MSG_LED_ON, strlen(MSG_LED_ON)))
  {
	  strcpy((char *)BuffTx, "m4:led on
");
	  printf("%s
", BuffTx);
	  VIRT_UART_Transmit(&huart0, BuffTx, strlen((const char *)BuffTx));
	  HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_RESET);
  }
 
  if (!strncmp((char *)VirtUart0ChannelBuffRx, MSG_LED_OFF, strlen(MSG_LED_OFF)))
  {
	  strcpy((char *)BuffTx, "m4:led off
");
	  printf("%s
", BuffTx);
	  VIRT_UART_Transmit(&huart0, BuffTx, strlen((const char *)BuffTx));
	  HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_SET);
  }
  memset(VirtUart0ChannelBuffRx, 0 ,VirtUart0ChannelRxSize);
  memset(BuffTx, 0 ,strlen((const char *)BuffTx));
}

6.VirUART1接收休眠唤醒指令
每次VirtUart1RxMsg发生变化，说明VirUART1收到了数据。
然后比较收到的数据内容，执行对应的操作。
这里，M4收到MSG_STOP(*stop)则进入CStop模式，中途A7再发任意数据给M4，由于IPCC也可设置为中断唤醒源，将M4唤醒；M4收到MSG_DELAY(*delay)则等待20S后发数据给A7，在这20S内，将A7先休眠，随后将被M4唤醒。

if (VirtUart1RxMsg)
{
  VirtUart1RxMsg = RESET;
 
  if (!strncmp((char *)VirtUart1ChannelBuffRx, MSG_STOP, strlen(MSG_STOP)))
  {
	  strcpy((char *)BuffTx, "m4:stop
");
	  printf("%s
", BuffTx);
	  VIRT_UART_Transmit(&huart1, BuffTx, strlen((const char *)BuffTx));
 
	  //RCC_backupClocks();
	  /* Clear the MCU flags before going into CSTOP */
	  SET_BIT(PWR->MCUCR, PWR_MCUCR_CSSF);
 
	  printf("Going to CStop mode
");
	  /* (C)STOP protection mechanism
	   * Only the IT with the highest priority (0 value) can interrupt.
	   * RCC_WAKEUP_IRQn IT is intended to have the highest priority and to be the
	   * only one IT having this value
	   * RCC_WAKEUP_IRQn is generated only when RCC is completely resumed from
	   * CSTOP */
	   __set_BASEPRI(1 << (8 - __NVIC_PRIO_BITS));
 
	   HAL_PWR_EnterSTOPMode(PWR_MAINREGULATOR_ON, PWR_STOPENTRY_WFI);
 
	   /* To allow Systick to increment after CSTOP (Eg.: to not block during
	    * TIMEOUT routines), TICK_INT_PRIORITY < BASEPRI
	    * For this example as TICK_INT_PRIORITY = 1, BASEPRI should be 2  */
	   __set_BASEPRI(2 << (8 - __NVIC_PRIO_BITS));
 
	   printf("Leaving CStop mode
");
 
	   /* Test if system was on STOP mode */
	   if( (PWR->MCUCR & PWR_MCUCR_STOPF) == PWR_MCUCR_STOPF)
	   {
		  printf("System was on STOP mode
");
 
	      /* Clear the MCU flags */
	      SET_BIT(PWR->MCUCR, PWR_MCUCR_CSSF);
 
	      /* Restore clocks */
	      /*
	      if (RCC_restoreClocks() == HAL_OK)
	      {
	    	  printf("CM4 restored clocks successfully
");
	      }
	      */
	    }
 
	    /* All level of ITs can interrupt */
	    __set_BASEPRI(0U);
  }
 
  if (!strncmp((char *)VirtUart1ChannelBuffRx, MSG_DELAY, strlen(MSG_DELAY)))
  {
	  printf("Waiting 20 secs before sending the answer message
");
	  HAL_Delay(20 *1000);
 
	  strcpy((char *)BuffTx, "m4:wakeup A7
");
	  printf("%s
", BuffTx);
	  VIRT_UART_Transmit(&huart1, BuffTx, strlen((const char *)BuffTx));
  }
  memset(VirtUart1ChannelBuffRx, 0 ,VirtUart1ChannelRxSize);
  memset(BuffTx, 0 ,strlen((const char *)BuffTx));
}

为了A7能发消息将M4唤醒，还需要IPCC作为M4的中断唤醒源。

EXTI_ConfigTypeDef EXTI_ConfigStructure;
EXTI_HandleTypeDef hexti62;
/*
 * Set configuration of Exti line 62 (IPCC interrupt CPU2). It could be used to wakeup the
 * M4 from CStop mode when RPMsg received from Cortex-A7
 */
EXTI_ConfigStructure.Line = EXTI_LINE_62;
EXTI_ConfigStructure.Mode = EXTI_MODE_C2_INTERRUPT;
//PERIPH_LOCK(EXTI);
HAL_EXTI_SetConfigLine(&hexti62, &EXTI_ConfigStructure);
//PERIPH_UNLOCK(EXTI);
 
/*
 *     Enable RCC_IT_WKUP to exit M4 from CStop mode.
 *     Indeed, due to SOC issue, M4 firmware shall make sure
 *     RCC_WAKEUP interrupt is the first one used to exit M4 from CStop mode.
 *     Therefore, M4 masks all NVIC interrupts with priority higher than 0
 *     before entering CStop mode and unmasks them when moving from WFI.
 *     (in HAL_PWR_EnterSTOPMode function)
 *     Note: All other NVIC interrupts shall be set to a different value
 *     from 0 to make sure that this workaround works well.
 */
 __HAL_RCC_ENABLE_IT(RCC_IT_WKUP);

3.1.3 M4完整代码

[main.c]

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2020 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
 
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "openamp.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "virt_uart.h"
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* USER CODE END PTD */
 
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
#define MAX_BUFFER_SIZE RPMSG_BUFFER_SIZE
/* USER CODE END PD */
 
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
 
/* USER CODE END PM */
 
/* Private variables ---------------------------------------------------------*/
IPCC_HandleTypeDef hipcc;
 
UART_HandleTypeDef huart5;
 
/* USER CODE BEGIN PV */
VIRT_UART_HandleTypeDef huart0;
VIRT_UART_HandleTypeDef huart1;
 
__IO FlagStatus VirtUart0RxMsg = RESET;
uint8_t VirtUart0ChannelBuffRx[MAX_BUFFER_SIZE];
uint16_t VirtUart0ChannelRxSize = 0;
 
__IO FlagStatus VirtUart1RxMsg = RESET;
uint8_t VirtUart1ChannelBuffRx[MAX_BUFFER_SIZE];
uint16_t VirtUart1ChannelRxSize = 0;
 
uint8_t BuffTx[MAX_BUFFER_SIZE];
 
#define MSG_LED_ON "*led_on"
#define MSG_LED_OFF "*led_off"
#define MSG_STOP "*stop"
#define MSG_DELAY "*delay"
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_IPCC_Init(void);
static void MX_UART5_Init(void);
int MX_OPENAMP_Init(int RPMsgRole, rpmsg_ns_bind_cb ns_bind_cb);
/* USER CODE BEGIN PFP */
void VIRT_UART0_RxCpltCallback(VIRT_UART_HandleTypeDef *huart);
void VIRT_UART1_RxCpltCallback(VIRT_UART_HandleTypeDef *huart);
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
#ifdef __GNUC__
	/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
     set to 'Yes') calls __io_putchar() */
	#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
	#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */
PUTCHAR_PROTOTYPE
{
	/* Place your implementation of fputc here */
	HAL_UART_Transmit(&huart5, (uint8_t *)&ch, 1, HAL_MAX_DELAY);
	return ch;
}
/* USER CODE END 0 */
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */
 
  /* USER CODE END 1 */
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  if(IS_ENGINEERING_BOOT_MODE())
  {
    /* Configure the system clock */
    SystemClock_Config();
  }
 
  /* IPCC initialisation */
   MX_IPCC_Init();
  /* OpenAmp initialisation ---------------------------------*/
  MX_OPENAMP_Init(RPMSG_REMOTE, NULL);
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_UART5_Init();
  /* USER CODE BEGIN 2 */
  printf("RPMsg user mode test
");
 
  if (VIRT_UART_Init(&huart0) != VIRT_UART_OK) {
	  printf("VIRT_UART_Init UART0 failed.
");
    Error_Handler();
  }
 
  if (VIRT_UART_Init(&huart1) != VIRT_UART_OK) {
	  printf("VIRT_UART_Init UART1 failed.
");
    Error_Handler();
  }
 
  if(VIRT_UART_RegisterCallback(&huart0, VIRT_UART_RXCPLT_CB_ID, VIRT_UART0_RxCpltCallback) != VIRT_UART_OK)
  {
   Error_Handler();
  }
 
  if(VIRT_UART_RegisterCallback(&huart1, VIRT_UART_RXCPLT_CB_ID, VIRT_UART1_RxCpltCallback) != VIRT_UART_OK)
  {
   Error_Handler();
  }
 
  EXTI_ConfigTypeDef EXTI_ConfigStructure;
  EXTI_HandleTypeDef hexti62;
  /*
   * Set configuration of Exti line 62 (IPCC interrupt CPU2). It could be used to wakeup the
   * M4 from CStop mode when RPMsg received from Cortex-A7
   */
  EXTI_ConfigStructure.Line = EXTI_LINE_62;
  EXTI_ConfigStructure.Mode = EXTI_MODE_C2_INTERRUPT;
  //PERIPH_LOCK(EXTI);
  HAL_EXTI_SetConfigLine(&hexti62, &EXTI_ConfigStructure);
  //PERIPH_UNLOCK(EXTI);
 
  /*
   *     Enable RCC_IT_WKUP to exit M4 from CStop mode.
   *     Indeed, due to SOC issue, M4 firmware shall make sure
   *     RCC_WAKEUP interrupt is the first one used to exit M4 from CStop mode.
   *     Therefore, M4 masks all NVIC interrupts with priority higher than 0
   *     before entering CStop mode and unmasks them when moving from WFI.
   *     (in HAL_PWR_EnterSTOPMode function)
   *     Note: All other NVIC interrupts shall be set to a different value
   *     from 0 to make sure that this workaround works well.
   */
   __HAL_RCC_ENABLE_IT(RCC_IT_WKUP);
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	 OPENAMP_check_for_message();
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
	if (VirtUart0RxMsg)
	{
	  VirtUart0RxMsg = RESET;
 
	  if (!strncmp((char *)VirtUart0ChannelBuffRx, MSG_LED_ON, strlen(MSG_LED_ON)))
	  {
		  strcpy((char *)BuffTx, "m4:led on
");
		  printf("%s
", BuffTx);
		  VIRT_UART_Transmit(&huart0, BuffTx, strlen((const char *)BuffTx));
		  HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_RESET);
	  }
 
	  if (!strncmp((char *)VirtUart0ChannelBuffRx, MSG_LED_OFF, strlen(MSG_LED_OFF)))
	  {
		  strcpy((char *)BuffTx, "m4:led off
");
		  printf("%s
", BuffTx);
		  VIRT_UART_Transmit(&huart0, BuffTx, strlen((const char *)BuffTx));
		  HAL_GPIO_WritePin(LED_BLUE_GPIO_Port, LED_BLUE_Pin, GPIO_PIN_SET);
	  }
	  memset(VirtUart0ChannelBuffRx, 0 ,VirtUart0ChannelRxSize);
	  memset(BuffTx, 0 ,strlen((const char *)BuffTx));
	}
 
	if (VirtUart1RxMsg)
	{
	  VirtUart1RxMsg = RESET;
 
	  if (!strncmp((char *)VirtUart1ChannelBuffRx, MSG_STOP, strlen(MSG_STOP)))
	  {
		  strcpy((char *)BuffTx, "m4:stop
");
		  printf("%s
", BuffTx);
		  VIRT_UART_Transmit(&huart1, BuffTx, strlen((const char *)BuffTx));
 
		  //RCC_backupClocks();
		  /* Clear the MCU flags before going into CSTOP */
		  SET_BIT(PWR->MCUCR, PWR_MCUCR_CSSF);
 
		  printf("Going to CStop mode
");
		  /* (C)STOP protection mechanism
		   * Only the IT with the highest priority (0 value) can interrupt.
		   * RCC_WAKEUP_IRQn IT is intended to have the highest priority and to be the
		   * only one IT having this value
		   * RCC_WAKEUP_IRQn is generated only when RCC is completely resumed from
		   * CSTOP */
		   __set_BASEPRI(1 << (8 - __NVIC_PRIO_BITS));
 
		   HAL_PWR_EnterSTOPMode(PWR_MAINREGULATOR_ON, PWR_STOPENTRY_WFI);
 
		   /* To allow Systick to increment after CSTOP (Eg.: to not block during
		    * TIMEOUT routines), TICK_INT_PRIORITY < BASEPRI
		    * For this example as TICK_INT_PRIORITY = 1, BASEPRI should be 2  */
		   __set_BASEPRI(2 << (8 - __NVIC_PRIO_BITS));
 
		   printf("Leaving CStop mode
");
 
		   /* Test if system was on STOP mode */
		   if( (PWR->MCUCR & PWR_MCUCR_STOPF) == PWR_MCUCR_STOPF)
		   {
			  printf("System was on STOP mode
");
 
		      /* Clear the MCU flags */
		      SET_BIT(PWR->MCUCR, PWR_MCUCR_CSSF);
 
		      /* Restore clocks */
		      /*
		      if (RCC_restoreClocks() == HAL_OK)
		      {
		    	  printf("CM4 restored clocks successfully
");
		      }
		      */
		    }
 
		    /* All level of ITs can interrupt */
		    __set_BASEPRI(0U);
	  }
 
	  if (!strncmp((char *)VirtUart1ChannelBuffRx, MSG_DELAY, strlen(MSG_DELAY)))
	  {
		  printf("Waiting 20 secs before sending the answer message
");
		  HAL_Delay(20 *1000);
 
		  strcpy((char *)BuffTx, "m4:wakeup A7
");
		  printf("%s
", BuffTx);
		  VIRT_UART_Transmit(&huart1, BuffTx, strlen((const char *)BuffTx));
	  }
	  memset(VirtUart1ChannelBuffRx, 0 ,VirtUart1ChannelRxSize);
	  memset(BuffTx, 0 ,strlen((const char *)BuffTx));
	}
 
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.HSIDivValue = RCC_HSI_DIV1;
  RCC_OscInitStruct.LSIState = RCC_LSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  RCC_OscInitStruct.PLL2.PLLState = RCC_PLL_NONE;
  RCC_OscInitStruct.PLL3.PLLState = RCC_PLL_NONE;
  RCC_OscInitStruct.PLL4.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** RCC Clock Config 
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_ACLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
                              |RCC_CLOCKTYPE_PCLK3|RCC_CLOCKTYPE_PCLK4
                              |RCC_CLOCKTYPE_PCLK5;
  RCC_ClkInitStruct.AXISSInit.AXI_Clock = RCC_AXISSOURCE_HSI;
  RCC_ClkInitStruct.AXISSInit.AXI_Div = RCC_AXI_DIV1;
  RCC_ClkInitStruct.MCUInit.MCU_Clock = RCC_MCUSSOURCE_HSI;
  RCC_ClkInitStruct.MCUInit.MCU_Div = RCC_MCU_DIV1;
  RCC_ClkInitStruct.APB4_Div = RCC_APB4_DIV1;
  RCC_ClkInitStruct.APB5_Div = RCC_APB5_DIV1;
  RCC_ClkInitStruct.APB1_Div = RCC_APB1_DIV1;
  RCC_ClkInitStruct.APB2_Div = RCC_APB2_DIV1;
  RCC_ClkInitStruct.APB3_Div = RCC_APB3_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief IPCC Initialization Function
  * @param None
  * @retval None
  */
static void MX_IPCC_Init(void)
{
 
  /* USER CODE BEGIN IPCC_Init 0 */
 
  /* USER CODE END IPCC_Init 0 */
 
  /* USER CODE BEGIN IPCC_Init 1 */
 
  /* USER CODE END IPCC_Init 1 */
  hipcc.Instance = IPCC;
  if (HAL_IPCC_Init(&hipcc) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN IPCC_Init 2 */
 
  /* USER CODE END IPCC_Init 2 */
 
}
 
/**
  * @brief UART5 Initialization Function
  * @param None
  * @retval None
  */
static void MX_UART5_Init(void)
{
 
  /* USER CODE BEGIN UART5_Init 0 */
 
  /* USER CODE END UART5_Init 0 */
 
  /* USER CODE BEGIN UART5_Init 1 */
 
  /* USER CODE END UART5_Init 1 */
  huart5.Instance = UART5;
  huart5.Init.BaudRate = 115200;
  huart5.Init.WordLength = UART_WORDLENGTH_8B;
  huart5.Init.StopBits = UART_STOPBITS_1;
  huart5.Init.Parity = UART_PARITY_NONE;
  huart5.Init.Mode = UART_MODE_TX_RX;
  huart5.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart5.Init.OverSampling = UART_OVERSAMPLING_16;
  huart5.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart5.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart5.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart5) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart5, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart5, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart5) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN UART5_Init 2 */
 
  /* USER CODE END UART5_Init 2 */
 
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
 
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOB_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();
 
  /*Configure GPIO pin : LED_BLUE_Pin */
  GPIO_InitStruct.Pin = LED_BLUE_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
  HAL_GPIO_Init(LED_BLUE_GPIO_Port, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
void VIRT_UART0_RxCpltCallback(VIRT_UART_HandleTypeDef *huart)
{
    printf("Msg received on VIRTUAL UART0 channel:  %s 
", (char *) huart->pRxBuffPtr);
 
    /* copy received msg in a variable to sent it back to master processor in main infinite loop*/
    VirtUart0ChannelRxSize = huart->RxXferSize < MAX_BUFFER_SIZE? huart->RxXferSize : MAX_BUFFER_SIZE-1;
    memcpy(VirtUart0ChannelBuffRx, huart->pRxBuffPtr, VirtUart0ChannelRxSize);
    VirtUart0RxMsg = SET;
}
 
void VIRT_UART1_RxCpltCallback(VIRT_UART_HandleTypeDef *huart)
{
    printf("Msg received on VIRTUAL UART1 channel:  %s 
", (char *) huart->pRxBuffPtr);
 
    /* copy received msg in a variable to sent it back to master processor in main infinite loop*/
    VirtUart1ChannelRxSize = huart->RxXferSize < MAX_BUFFER_SIZE? huart->RxXferSize : MAX_BUFFER_SIZE-1;
    memcpy(VirtUart1ChannelBuffRx, huart->pRxBuffPtr, VirtUart1ChannelRxSize);
    VirtUart1RxMsg = SET;
}
/* USER CODE END 4 */
 
/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
 
  /* USER CODE END Error_Handler_Debug */
}
 
#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{ 
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     tex: printf("Wrong parameters value: file %s on line %d
", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

3.1.4 测试效果

1.测试A7命令M4控制LED灯
首先将前面编译生成的rpmsg_user_CM4.elf放在/lib/firmware目录下。
然后启动固件，此时看到打印信息里提示创建了两个通道ttyRPMSG0和ttyRPMSG1，同时M4也打印了测试开始信息。

1

2

3

cd /sys/class/remoteproc/remoteproc0

echo rpmsg_user_CM4.elf > firmware

echo start > state

然后还需要设置虚拟串口/dev/ttyRPMSG0。
-onlcr是不将NL字符映射为CR-NL字符，就是说发送给M4的数据，不会自动加上回车，不然这里发送led_on，M4收到的为led_on，正确的应该是收到*led_on。
-echo是禁止回显，以方便查看接收的字符。

1 2	stty -onlcr -echo -F /dev/ttyRPMSG0 cat /dev/ttyRPMSG0 &

最后，向/dev/ttyRPMSG0写入预定义的指令，M4收到指令便会控制LED灯，并发送结果给A7。

1 2	echo "led_on" > /dev/ttyRPMSG0 echo "led_off" > /dev/ttyRPMSG0

2.测试A7和M4休眠唤醒
接着前面，启动M4后。
首先设置虚拟串口/dev/ttyRPMSG1。

1

2

stty -onlcr -echo -F /dev/ttyRPMSG1

cat /dev/ttyRPMSG1 &

然后向/dev/ttyRPMSG1写入*stop，M4随后卡在打印Going to CStop mode后，接着向/dev/ttyRPMSG1写入wakeup(任意字符即可)，M4随后打印Leaving CStop mode。即实现了A7控制M4的休眠和唤醒。

1 2	echo "*stop" > /dev/ttyRPMSG1 echo "wakeup" >/dev/ttyRPMSG1

再测试M4唤醒A7。
先使能A7唤醒，然后向/dev/ttyRPMSG1写入*delay，M4收到指令后，20S后会向A7发数据，从而唤醒A7。
此时控制A7进入休眠状态，20S后，A7被唤醒。

1
2
3

echo enabled > /sys/devices/platform/soc/4c001000.mailbox/power/wakeup
echo "*delay" > /dev/ttyRPMSG1
echo mem > /sys/power/state

3.2 内核态的通信

3.2.1 A7准备

内核已经提供了示例驱动程序linux-origin_master/samples/rpmsg/rpmsg_client_sample.c，这里直接使用该驱动，简单的修改了下打印内容，方便查看。

[rpmsg_client_sample.c]

/*
 * Remote processor messaging - sample client driver
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Copyright (C) 2011 Google, Inc.
 *
 * Ohad Ben-Cohen <ohad@wizery.com>
 * Brian Swetland <swetland@google.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
 
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rpmsg.h>
 
#define MSG		"hello world! A7->M4"
#define MSG_LIMIT	100
 
struct instance_data {
	int rx_count;
};
 
static int rpmsg_sample_cb(struct rpmsg_device *rpdev, void *data, int len,
						void *priv, u32 src)
{
	int ret;
	struct instance_data *idata = dev_get_drvdata(&rpdev->dev);
 
	//dev_info(&rpdev->dev, "incoming msg %d (src: 0x%x)
", ++idata->rx_count, src);
	//print_hex_dump(KERN_DEBUG, __func__, DUMP_PREFIX_NONE, 16, 1, data, len,  true);
 
	printk(KERN_DEBUG "received_rpmsg: %s %d 
", data, ++idata->rx_count);
 
 
	/* samples should not live forever */
	if (idata->rx_count >= MSG_LIMIT) {
		//dev_info(&rpdev->dev, "goodbye!
");
		return 0;
	}
 
	/* send a new message now */
	ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
	if (ret)
		dev_err(&rpdev->dev, "rpmsg_send failed: %d
", ret);
	else
		printk(KERN_DEBUG "send_rpmsg: %s 
", MSG);
 
	return 0;
}
 
static int rpmsg_sample_probe(struct rpmsg_device *rpdev)
{
	int ret;
	struct instance_data *idata;
 
	dev_info(&rpdev->dev, "new channel: 0x%x -> 0x%x!
",
					rpdev->src, rpdev->dst);
 
	idata = devm_kzalloc(&rpdev->dev, sizeof(*idata), GFP_KERNEL);
	if (!idata)
		return -ENOMEM;
 
	dev_set_drvdata(&rpdev->dev, idata);
 
	/* send a message to our remote processor */
	ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
	if (ret) {
		dev_err(&rpdev->dev, "rpmsg_send failed: %d
", ret);
		return ret;
	}
	else
		printk(KERN_DEBUG "send_rpmsg: %s 
", MSG);
 
	return 0;
}
 
static void rpmsg_sample_remove(struct rpmsg_device *rpdev)
{
	dev_info(&rpdev->dev, "rpmsg sample client driver is removed
");
}
 
static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
	{ .name	= "rpmsg-client-sample" },
	{ },
};
MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_sample_id_table);
 
static struct rpmsg_driver rpmsg_sample_client = {
	.drv.name	= KBUILD_MODNAME,
	.id_table	= rpmsg_driver_sample_id_table,
	.probe		= rpmsg_sample_probe,
	.callback	= rpmsg_sample_cb,
	.remove		= rpmsg_sample_remove,
};
module_rpmsg_driver(rpmsg_sample_client);
 
MODULE_DESCRIPTION("Remote processor messaging sample client driver");
MODULE_LICENSE("GPL v2");

驱动比较简单，核心是rpmsg_sample_cb()，rpmsg收到数据后将回调该函数。
从data获得M4发来的数据，通过rpmsg_send()将数据发给M4。
将该驱动编译成模块，并在A7中加载。

3.2.2 M4准备

参考前面的示例，依次在STM32CubeMX配置UART5、IPCC和OPENAMP，然后生成初始化代码。

1.建一个rpmsg通道

1

OPENAMP_create_endpoint(&resmgr_ept, RPMSG_SERVICE_NAME, RPMSG_ADDR_ANY, rx_callback, NULL);

注意这里的RPMSG_SERVICE_NAME和驱动里rpmsg_device_id结构体的.name的名字一样。
之后，一旦rpmsg通道数据，将回调rx_callback()函数。

2.编写接收回调函数
此函数里，需要将接收的数据复制到用户内存，并修改接收标志位。

static int rx_callback(struct rpmsg_endpoint *rp_chnl, void *data, size_t len, uint32_t src, void *priv)
{
  /* copy received msg, and raise a flag  */
  memcpy(received_rpmsg, data, len > sizeof(received_rpmsg) ? sizeof(received_rpmsg) : len);
  printf("received_rpmsg=%s
", received_rpmsg);
  rx_status = SET;
  return 0;

3.主函数轮询RPMsg消息
OPENAMP_check_for_message()查询MailBox状态。
当收到数据时，rx_callback()会保存好收到数据，然后修改rx_status标志位。
主函数里发现rx_status标志位发生变化时，即可获取接收的数据。

 while (1)
 {
OPENAMP_check_for_message();
   /* USER CODE END WHILE */
if (rx_status == SET)
{
  /* Message received: send back a message anwser */
  rx_status = RESET;
 
 /*rpmsg收到数据*/
}
   /* USER CODE BEGIN 3 */
 }

4.向M4发送数据
使用OPENAMP_send()向A7发送数据。

 if (++count < 100)
sprintf((char *)msg, "hello world! M4->A7 %02ld", count);
 else
strcpy((char *)msg, "goodbye!");
 
 if (OPENAMP_send(&resmgr_ept, msg, strlen((char *)msg) + 1) < 0)
 {
printf("Failed to send message
");
Error_Handler();
 }
 else
printf("send_rpmsg=%s
", msg);

3.2.3 M4完整代码

[main.c]

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2020 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
 
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "openamp.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
 
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* USER CODE END PTD */
 
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
#define RPMSG_SERVICE_NAME              "rpmsg-client-sample"
/* USER CODE END PD */
 
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
 
/* USER CODE END PM */
 
/* Private variables ---------------------------------------------------------*/
IPCC_HandleTypeDef hipcc;
 
UART_HandleTypeDef huart5;
 
/* USER CODE BEGIN PV */
__IO FlagStatus rx_status = RESET;
uint8_t received_rpmsg[128];
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_IPCC_Init(void);
static void MX_UART5_Init(void);
int MX_OPENAMP_Init(int RPMsgRole, rpmsg_ns_bind_cb ns_bind_cb);
/* USER CODE BEGIN PFP */
static int rx_callback(struct rpmsg_endpoint *rp_chnl, void *data, size_t len, uint32_t src, void *priv);
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
#ifdef __GNUC__
	/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
     set to 'Yes') calls __io_putchar() */
	#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
	#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */
PUTCHAR_PROTOTYPE
{
	/* Place your implementation of fputc here */
	HAL_UART_Transmit(&huart5, (uint8_t *)&ch, 1, HAL_MAX_DELAY);
	return ch;
}
/* USER CODE END 0 */
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */
  struct rpmsg_endpoint resmgr_ept;
  uint32_t count = 0;
  uint8_t msg[32];
  /* USER CODE END 1 */
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  if(IS_ENGINEERING_BOOT_MODE())
  {
    /* Configure the system clock */
    SystemClock_Config();
  }
 
  /* IPCC initialisation */
   MX_IPCC_Init();
  /* OpenAmp initialisation ---------------------------------*/
  MX_OPENAMP_Init(RPMSG_REMOTE, NULL);
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_UART5_Init();
  /* USER CODE BEGIN 2 */
  printf("RPMsg kernel mode test
");
  /* Create an rpmsg channel to communicate with the Master processor CPU1(CA7) */
  OPENAMP_create_endpoint(&resmgr_ept, RPMSG_SERVICE_NAME, RPMSG_ADDR_ANY,
		  rx_callback, NULL);
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	OPENAMP_check_for_message();
    /* USER CODE END WHILE */
	if (rx_status == SET)
	{
	  /* Message received: send back a message anwser */
	  rx_status = RESET;
 
	  if (++count < 100)
		sprintf((char *)msg, "hello world! M4->A7 %02ld", count);
	  else
		strcpy((char *)msg, "goodbye!");
 
	  if (OPENAMP_send(&resmgr_ept, msg, strlen((char *)msg) + 1) < 0)
	  {
		printf("Failed to send message
");
		Error_Handler();
	  }
	  else
		printf("send_rpmsg=%s
", msg);
	}
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.HSIDivValue = RCC_HSI_DIV1;
  RCC_OscInitStruct.LSIState = RCC_LSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  RCC_OscInitStruct.PLL2.PLLState = RCC_PLL_NONE;
  RCC_OscInitStruct.PLL3.PLLState = RCC_PLL_NONE;
  RCC_OscInitStruct.PLL4.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** RCC Clock Config 
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_ACLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
                              |RCC_CLOCKTYPE_PCLK3|RCC_CLOCKTYPE_PCLK4
                              |RCC_CLOCKTYPE_PCLK5;
  RCC_ClkInitStruct.AXISSInit.AXI_Clock = RCC_AXISSOURCE_HSI;
  RCC_ClkInitStruct.AXISSInit.AXI_Div = RCC_AXI_DIV1;
  RCC_ClkInitStruct.MCUInit.MCU_Clock = RCC_MCUSSOURCE_HSI;
  RCC_ClkInitStruct.MCUInit.MCU_Div = RCC_MCU_DIV1;
  RCC_ClkInitStruct.APB4_Div = RCC_APB4_DIV1;
  RCC_ClkInitStruct.APB5_Div = RCC_APB5_DIV1;
  RCC_ClkInitStruct.APB1_Div = RCC_APB1_DIV1;
  RCC_ClkInitStruct.APB2_Div = RCC_APB2_DIV1;
  RCC_ClkInitStruct.APB3_Div = RCC_APB3_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief IPCC Initialization Function
  * @param None
  * @retval None
  */
static void MX_IPCC_Init(void)
{
 
  /* USER CODE BEGIN IPCC_Init 0 */
 
  /* USER CODE END IPCC_Init 0 */
 
  /* USER CODE BEGIN IPCC_Init 1 */
 
  /* USER CODE END IPCC_Init 1 */
  hipcc.Instance = IPCC;
  if (HAL_IPCC_Init(&hipcc) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN IPCC_Init 2 */
 
  /* USER CODE END IPCC_Init 2 */
 
}
 
/**
  * @brief UART5 Initialization Function
  * @param None
  * @retval None
  */
static void MX_UART5_Init(void)
{
 
  /* USER CODE BEGIN UART5_Init 0 */
 
  /* USER CODE END UART5_Init 0 */
 
  /* USER CODE BEGIN UART5_Init 1 */
 
  /* USER CODE END UART5_Init 1 */
  huart5.Instance = UART5;
  huart5.Init.BaudRate = 115200;
  huart5.Init.WordLength = UART_WORDLENGTH_8B;
  huart5.Init.StopBits = UART_STOPBITS_1;
  huart5.Init.Parity = UART_PARITY_NONE;
  huart5.Init.Mode = UART_MODE_TX_RX;
  huart5.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart5.Init.OverSampling = UART_OVERSAMPLING_16;
  huart5.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart5.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart5.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart5) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart5, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart5, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart5) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN UART5_Init 2 */
 
  /* USER CODE END UART5_Init 2 */
 
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
 
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOB_CLK_ENABLE();
 
}
 
/* USER CODE BEGIN 4 */
static int rx_callback(struct rpmsg_endpoint *rp_chnl, void *data, size_t len, uint32_t src, void *priv)
{
  /* copy received msg, and raise a flag  */
  memcpy(received_rpmsg, data, len > sizeof(received_rpmsg) ? sizeof(received_rpmsg) : len);
  printf("received_rpmsg=%s
", received_rpmsg);
  rx_status = SET;
  return 0;
}
/* USER CODE END 4 */
 
/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
 
  /* USER CODE END Error_Handler_Debug */
}
 
#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{ 
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     tex: printf("Wrong parameters value: file %s on line %d
", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

3.2.4 测试效果

首先加载驱动rpmsg_client_sample.ko，并修改打印等级。

1 2	insmod rpmsg_client_sample.ko echo 8 > /proc/sys/kernel/printk

然后加载M4固件，可以看到A7和M4都同时发送和接收到相互之间的数据。

1
2
3

cd /sys/class/remoteproc/remoteproc0
echo rpmsg_kernel_CM4.elf > firmware
echo start > state

本文采用知识共享署名-非商业性使用-相同方式共享 4.0 国际许可协议进行许可，欢迎转载，但转载请注明来自hceng blog，并保持转载后文章内容的完整。本人保留所有版权相关权利。

【作者】张昺华

【出处】http://www.cnblogs.com/sky-heaven/

【博客园】 http://www.cnblogs.com/sky-heaven/

【知乎】 http://www.zhihu.com/people/zhang-bing-hua

【我的作品---旋转倒立摆】 http://v.youku.com/v_show/id_XODM5NDAzNjQw.html?spm=a2hzp.8253869.0.0&from=y1.7-2

【我的作品---自平衡自动循迹车】 http://v.youku.com/v_show/id_XODM5MzYyNTIw.html?spm=a2hzp.8253869.0.0&from=y1.7-2

【大饼教你学系列】https://edu.csdn.net/course/detail/10393

【新浪微博】张昺华--sky

【twitter】 @sky2030_

【微信公众号】张昺华

本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利.

相关阅读:
spring-mvc----数据库数据到页面错误--tomcat启动不了
 springmvc注解@RequestMapping
数据库到jsp页面报错（一）
IDEA秒退或者一直让填写激活码问题
 spting Boot 创建一个springBoot项目
 SSM框架整合(实现从数据库到页面展示)
asp.net dbproviderfactory（提供程序工厂模型）多数据库访问
 connectionStrings 中的 providerName 属性
 IDisposable
利用提示引导语句运行
原文地址：https://www.cnblogs.com/sky-heaven/p/13556572.html