/**
  @page OpenAMP_TTY_echo OpenAMP TTY echo example started by Linux Remote Processor Framework

  @verbatim
  ******************** (C) COPYRIGHT 2019 STMicroelectronics *******************
  * @file    OpenAMP/OpenAMP_TTY_echo/Remoteproc/README
  * @author  MCD Application Team
  * @brief   How to run example using Linux Remote Processor Framework
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2019 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
  *
  ******************************************************************************
  @endverbatim

@par Description of M4 Cube example with Linux Remote Processor Framework

When Cube firmware is running on Cortex-M4, System Clock tree and regulators(vrefbuf) are configured by Cortex-A7
Besides, clock source for each peripheral assigned to Cortex-M4 is done by Cortex-A7.


@par How to use it ?

In order to make the program work with Linux running on Cortex-A7, you must do the following :
Before running M4 Cube example, you have to
1) interrupt uboot
2) choose the right configuration to make sure that M4 resources are assigned to Linux Resource Manager driver

Then,
 - Start example using the following command: "fw_cortex_m4.sh start" under example directory installed in userfs partition
     * it will load and start firmware using Linux Remote Processor
 - Stop example using the following command: "fw_cortex_m4.sh stop" under example directory installed in userfs partition
     * it will stop firmware using Linux Remote Processor

@par Example Description
How to use OpenAMP MW + Virtual UART to create an Inter-Processor Communication channel seen as TTY device in Linux OS.

This project deals with CPU2 (Cortex-M4) firmware and requires Linux OS running on CPU1 (Cortex-A7)
OpenAMP MW uses the following HW resources
    * IPCC peripheral for event signal (mailbox) between CPU1(CA7) and CPU2(CM4)
    * MCUSRAM peripheral for buffer communications (virtio buffers) between CPU1(CA7) and CPU2(CM4)
            Reserved shared memeory region for this example: SHM_ADDR=0x10040000 and SHM_SIZE=128k.
            It is defined in platform_info.c file

In this example:
    - CPU2(CM4) initialize OPenAMP MW which initializes/configures IPCC peripheral through HAL
    and setup openamp-rpmsg framwork infrastructure
    - CPU2(CM4) creates 2 rpmsg channels for 2 virtual UART instance UART0 and UART1
    - CPU2(CM4) is waiting for messages from CPU1(CA7) on these both channels
    - When CPU2(CM4) receives a message on 1 Virtual UART instance/rpmsg channel,
      it sends the message back to CPU1(CA7) on the same Virtual UART instance

    Notes:
    - It requires Linux console to run example.
    - CM4 logging is redirected in Shared memory in MCUSRAM and can be displayed in Linux console for verdict
      using following command:
          cat /sys/kernel/debug/remoteproc/remoteproc0/trace0

    Following command should be done in Linux console on CA7 to run the example :

    > stty -onlcr -echo -F /dev/ttyRPMSG0
    > cat /dev/ttyRPMSG0 &
    > stty -onlcr -echo -F /dev/ttyRPMSG1
    > cat /dev/ttyRPMSG1 &
    > echo "Hello Virtual UART0" >/dev/ttyRPMSG0
    > echo "Hello Virtual UART1" >/dev/ttyRPMSG1

    You should get "Hello Virtual UART0" and "Hello Virtual UART1" in Linux console

@note Care must be taken when using HAL_Delay(), this function provides accurate
      delay (in milliseconds) based on variable incremented in HAL time base ISR.
      This implies that if HAL_Delay() is called from a peripheral ISR process, then
      the HAL time base interrupt must have higher priority (numerically lower) than
      the peripheral interrupt. Otherwise the caller ISR process will be blocked.
      To change the HAL time base interrupt priority you have to use HAL_NVIC_SetPriority()
      function.

@note The application needs to ensure that the HAL time base is always set to 1 millisecond
      to have correct HAL operation.


@par Directory contents
    - OpenAMP/OpenAMP_TTY_echo/Inc/main.h                             Main program header file
    - OpenAMP/OpenAMP_TTY_echo/Inc/mbox_ipcc.h                        mailbox_ipcc_if.c MiddleWare configuration header file
    - OpenAMP/OpenAMP_TTY_echo/Inc/openamp.h                          User OpenAMP init header file
    - OpenAMP/OpenAMP_TTY_echo/Inc/openamp_conf.h                     Configuration file for OpenAMP MW
    - OpenAMP/OpenAMP_TTY_echo/Inc/rsc_table.h                        Resource_table for OpenAMP header file
    - OpenAMP/OpenAMP_TTY_echo/Inc/stm32mp1xx_hal_conf.h         HAL Library Configuration file
    - OpenAMP/OpenAMP_TTY_echo/Inc/stm32mp1xx_it.h               Interrupt handlers header file
    - OpenAMP/OpenAMP_TTY_echo/Src/main.c                             Main program
    - OpenAMP/OpenAMP_TTY_echo/Src/mbox_ipcc.c                        mailbox_ipcc_if.c MiddleWare configuration
    - OpenAMP/OpenAMP_TTY_echo/Src/openamp.c                          User OpenAMP init
    - OpenAMP/OpenAMP_TTY_echo/Src/rsc_table.c                        Resource_table for OpenAMP
    - OpenAMP/OpenAMP_TTY_echo/Src/stm32mp1xx_it.c               Interrupt handlers
    - OpenAMP/OpenAMP_TTY_echo/Src/system_stm32mp1xx.c           STM32MP1xx system clock configuration file


@par Hardware and Software environment

  - This example runs on STM32MP157CACx devices.

  - This example has been tested with STM32MP157C-DK2 board and can be
    easily tailored to any other supported device and development board.

@par How to use it ?

In order to make the program work, you must do the following:
 - Open your preferred toolchain
 - Rebuild all files and load your image into target memory
 - Run the example


 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */
