Function rpmsgmtd_write

drivers/mtd/rpmsgmtd.c:492–568

#ifdef CONFIG_MTD_BYTE_WRITE
static ssize_t rpmsgmtd_write(FAR struct mtd_dev_s *dev, off_t offset,
                              size_t nbytes, FAR const uint8_t *buffer)
{
  FAR struct rpmsgmtd_s *priv = (FAR struct rpmsgmtd_s *)dev;
  FAR struct rpmsgmtd_write_s *msg;
  struct rpmsgmtd_cookie_s cookie;
  uint32_t space;
  size_t written = 0;
  int ret;

  if (buffer == NULL)
    {
      return -EINVAL;
    }

  /* Sanity checks */

  DEBUGASSERT(priv != NULL);

  /* Perform the rpmsg write */

  memset(&cookie, 0, sizeof(cookie));
  nxsem_init(&cookie.sem, 0, 0);

  while (written < nbytes)
    {
      msg = rpmsgmtd_get_tx_payload_buffer(priv, &space);
      if (msg == NULL)
        {
          ret = -ENOMEM;
          goto out;
        }

      space -= sizeof(*msg) - 1;
      if (space >= nbytes - written)
        {
          /* Send complete, set cookie is valid, need ack */

          space = nbytes - written;
          msg->header.cookie = (uintptr_t)&cookie;
        }
      else
        {
          /* Not send complete, set cookie invalid, do not need ack */

          msg->header.cookie = 0;
        }

      msg->header.command = RPMSGMTD_WRITE;
      msg->header.result  = -ENXIO;
      msg->offset         = offset;
      msg->nbytes         = space;
      memcpy(msg->buf, buffer, space);

      ret = rpmsg_send_nocopy(&priv->ept, msg, sizeof(*msg) - 1 + space);
      if (ret < 0)
        {
          goto out;