VirtIOSerial.cpp

/**
 * MIT License:
 * Copyright (c) 2019 Bumsik kim <k.bumsik@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#if defined (VIRTIOCON)

#include "VirtIOSerial.h"
#include "core_debug.h"

#if !defined(VIRTIOSERIAL_NUM)
#define VIRTIOSERIAL_NUM    1
#endif

VirtIOSerialObj_t *VirtIOSerial_Handle[VIRTIOSERIAL_NUM] = {NULL};

uint32_t VirtIOSerial::VirtIOSerial_index = 0;

// Default instance
VirtIOSerial SerialVirtIO;

void serialEventVirtIO() __attribute__((weak));
VirtIOSerialObj_t *get_VirtIOSerial_obj(VIRT_UART_HandleTypeDef *huart);

void VirtIOSerial::begin(void)
{
  virtio_buffer_init(&_VirtIOSerialObj.ring);
  if (_VirtIOSerialObj.initialized) {
    return;
  }
  if (OPENAMP_Init() != 0) {
    Error_Handler();
  }
  if (VIRT_UART_Init(&_VirtIOSerialObj.handle) != VIRT_UART_OK) {
    Error_Handler();
  }

  VirtIOSerial_index ++;
  _VirtIOSerialObj.__this = (void *)this;

  /* Need to register callback for message reception by channels */
  if (VIRT_UART_RegisterCallback(&_VirtIOSerialObj.handle, VIRT_UART_RXCPLT_CB_ID, rxGenericCallback) != VIRT_UART_OK) {
    Error_Handler();
  }

  VirtIOSerial_Handle[VirtIOSerial_index] = &_VirtIOSerialObj;
  _VirtIOSerialObj.initialized = true;
  _VirtIOSerialObj.first_message_discarded = false;

  // This will wait for the first message "DUMMY", see rxCallback().
  OPENAMP_Wait_EndPointready(&_VirtIOSerialObj.handle.ept);
}

void VirtIOSerial::begin(uint32_t /* baud_count */)
{
  // uart config is ignored in OpenAMP
  begin();
}

void VirtIOSerial::begin(uint32_t /* baud_count */, uint8_t /* config */)
{
  // uart config is ignored in OpenAMP
  begin();
}

void VirtIOSerial::end()
{
  VIRT_UART_DeInit(&_VirtIOSerialObj.handle);
  OPENAMP_DeInit();
  virtio_buffer_init(&_VirtIOSerialObj.ring);
  _VirtIOSerialObj.initialized = false;
}

int VirtIOSerial::available(void)
{
  checkMessageFromISR();
  return virtio_buffer_read_available(&_VirtIOSerialObj.ring);
}

int VirtIOSerial::availableForWrite()
{
  checkMessageFromISR();
  // Just return max length of VIRT_UART_Transmit() can transmit.
  // See VIRT_UART_Transmit().
  return RPMSG_VRING_PAYLOAD_SIZE;
}

int VirtIOSerial::peek(void)
{
  checkMessageFromISR();
  if (virtio_buffer_read_available(&_VirtIOSerialObj.ring) > 0) {
    uint8_t tmp;
    virtio_buffer_peek(&_VirtIOSerialObj.ring, &tmp, 1);
    return tmp;
  } else {
    return -1;
  }
}

int VirtIOSerial::read(void)
{
  if (available() > 0) {
    char ch;
    readBytes(&ch, 1);
    return ch;
  } else {
    return -1;
  }
}

size_t VirtIOSerial::readBytes(char *buffer, size_t length)
{
  checkMessageFromISR();
  const size_t size = virtio_buffer_read(&_VirtIOSerialObj.ring, reinterpret_cast<uint8_t *>(buffer), length);
  // The ring buffer might be available enough to write after reading
  checkMessageFromISR();
  return size;
}

size_t VirtIOSerial::write(uint8_t ch)
{
  // Just write single-byte buffer.
  return write(&ch, 1);
}

// Warning: Currently VirtIOSerial implementation is synchronous, blocking
// until all bytes are sent. But it will be fast enough.
size_t VirtIOSerial::write(const uint8_t *buffer, size_t size)
{
  checkMessageFromISR();
  if (VIRT_UART_Transmit(&_VirtIOSerialObj.handle, const_cast<uint8_t *>(buffer), size) != VIRT_UART_OK) {
    // This error usually happens when size > 496. See VirtIOSerial::availableForWrite()
    core_debug("ERROR: VirtIOSerial::write() failed. Check availableForWrite().\n");
    return 0;
  }
  // It is likely receive "buf free" from the Linux host right after
  // VIRT_UART_Transmit(). So check it here too.
  checkMessageFromISR();
  return size;
}

void VirtIOSerial::flush(void)
{
  checkMessageFromISR();
  // write() is blocked until all bytes are sent. So flush() doesn't need to do
  // anything. See rpmsg_send().
  return;
}

/**
 * @brief Check if RPMsg message arrived from IPCC ISR
 * @note  This should called as mush as possible to consume RPMsg ring buffers,
 *        so that the host processor can send more messages quickly.
 */
void VirtIOSerial::checkMessageFromISR(void)
{
  OPENAMP_check_for_tx_message();
  if (virtio_buffer_write_available(&_VirtIOSerialObj.ring) >= RPMSG_VRING_TOTAL_PAYLOAD_SIZE) {
    // This calls rxCallback() VRING_NUM_BUFFS times at maximum
    OPENAMP_check_for_rx_message();
  }
}

void VirtIOSerial::rxGenericCallback(VIRT_UART_HandleTypeDef *huart)
{
  VirtIOSerialObj_t *obj = get_VirtIOSerial_obj(huart);
  VirtIOSerial *VIOS = (VirtIOSerial *)(obj->__this);

  VIOS->rxCallback(huart);
}

void VirtIOSerial::rxCallback(VIRT_UART_HandleTypeDef *huart)
{
  // Linux host must send a dummy data first to finish initialization of rpmsg
  // on the coprocessor side. This message should be discarded.
  // run_arduino_gen.sh script will send dummy data: "DUMMY".
  // See: https://github.com/OpenAMP/open-amp/issues/182
  // See: run_arduino_gen.sh
  if (!_VirtIOSerialObj.first_message_discarded) {
    huart->RxXferSize = 0;
    _VirtIOSerialObj.first_message_discarded = true;
  }

  size_t size = min(huart->RxXferSize, virtio_buffer_write_available(&_VirtIOSerialObj.ring));
  while (size > 0) {
    size -= virtio_buffer_write(&_VirtIOSerialObj.ring, huart->pRxBuffPtr, size);
  }
}

/* Aim of the function is to get _VirtIOSerialObj pointer using huart pointer */
/* Highly inspired from magical linux kernel's "container_of" */
VirtIOSerialObj_t *get_VirtIOSerial_obj(VIRT_UART_HandleTypeDef *huart)
{
  VirtIOSerialObj_t *obj;
  obj = (VirtIOSerialObj_t *)((char *)huart - offsetof(VirtIOSerialObj_t, handle));
  return (obj);
}

#endif /* VIRTIOCON */