+#ifdef CONFIG_SERIAL_SH_SCI_DMA
+static void sci_dma_tx_complete(void *arg)
+{
+ struct sci_port *s = arg;
+ struct uart_port *port = &s->port;
+ struct circ_buf *xmit = &port->state->xmit;
+ unsigned long flags;
+
+ dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ xmit->tail += s->sg_tx.length;
+ xmit->tail &= UART_XMIT_SIZE - 1;
+
+ port->icount.tx += s->sg_tx.length;
+
+ async_tx_ack(s->desc_tx);
+ s->cookie_tx = -EINVAL;
+ s->desc_tx = NULL;
+
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+ uart_write_wakeup(port);
+
+ if (uart_circ_chars_pending(xmit))
+ schedule_work(&s->work_tx);
+}
+
+/* Locking: called with port lock held */
+static int sci_dma_rx_push(struct sci_port *s, struct tty_struct *tty,
+ size_t count)
+{
+ struct uart_port *port = &s->port;
+ int i, active, room;
+
+ room = tty_buffer_request_room(tty, count);
+
+ if (s->active_rx == s->cookie_rx[0]) {
+ active = 0;
+ } else if (s->active_rx == s->cookie_rx[1]) {
+ active = 1;
+ } else {
+ dev_err(port->dev, "cookie %d not found!\n", s->active_rx);
+ return 0;
+ }
+
+ if (room < count)
+ dev_warn(port->dev, "Rx overrun: dropping %u bytes\n",
+ count - room);
+ if (!room)
+ return room;
+
+ for (i = 0; i < room; i++)
+ tty_insert_flip_char(tty, ((u8 *)sg_virt(&s->sg_rx[active]))[i],
+ TTY_NORMAL);
+
+ port->icount.rx += room;
+
+ return room;
+}
+
+static void sci_dma_rx_complete(void *arg)
+{
+ struct sci_port *s = arg;
+ struct uart_port *port = &s->port;
+ struct tty_struct *tty = port->state->port.tty;
+ unsigned long flags;
+ int count;
+
+ dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ count = sci_dma_rx_push(s, tty, s->buf_len_rx);
+
+ mod_timer(&s->rx_timer, jiffies + msecs_to_jiffies(5));
+
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ if (count)
+ tty_flip_buffer_push(tty);
+
+ schedule_work(&s->work_rx);
+}
+
+static void sci_start_rx(struct uart_port *port);
+static void sci_start_tx(struct uart_port *port);
+
+static void sci_rx_dma_release(struct sci_port *s, bool enable_pio)
+{
+ struct dma_chan *chan = s->chan_rx;
+ struct uart_port *port = &s->port;
+ unsigned long flags;
+
+ s->chan_rx = NULL;
+ s->cookie_rx[0] = s->cookie_rx[1] = -EINVAL;
+ dma_release_channel(chan);
+ dma_free_coherent(port->dev, s->buf_len_rx * 2,
+ sg_virt(&s->sg_rx[0]), sg_dma_address(&s->sg_rx[0]));
+ if (enable_pio)
+ sci_start_rx(port);
+}
+
+static void sci_tx_dma_release(struct sci_port *s, bool enable_pio)
+{
+ struct dma_chan *chan = s->chan_tx;
+ struct uart_port *port = &s->port;
+ unsigned long flags;
+
+ s->chan_tx = NULL;
+ s->cookie_tx = -EINVAL;
+ dma_release_channel(chan);
+ if (enable_pio)
+ sci_start_tx(port);
+}
+
+static void sci_submit_rx(struct sci_port *s)
+{
+ struct dma_chan *chan = s->chan_rx;
+ int i;
+
+ for (i = 0; i < 2; i++) {
+ struct scatterlist *sg = &s->sg_rx[i];
+ struct dma_async_tx_descriptor *desc;
+
+ desc = chan->device->device_prep_slave_sg(chan,
+ sg, 1, DMA_FROM_DEVICE, DMA_PREP_INTERRUPT);
+
+ if (desc) {
+ s->desc_rx[i] = desc;
+ desc->callback = sci_dma_rx_complete;
+ desc->callback_param = s;
+ s->cookie_rx[i] = desc->tx_submit(desc);
+ }
+
+ if (!desc || s->cookie_rx[i] < 0) {
+ if (i) {
+ async_tx_ack(s->desc_rx[0]);
+ s->cookie_rx[0] = -EINVAL;
+ }
+ if (desc) {
+ async_tx_ack(desc);
+ s->cookie_rx[i] = -EINVAL;
+ }
+ dev_warn(s->port.dev,
+ "failed to re-start DMA, using PIO\n");
+ sci_rx_dma_release(s, true);
+ return;
+ }
+ }
+
+ s->active_rx = s->cookie_rx[0];
+
+ dma_async_issue_pending(chan);
+}
+
+static void work_fn_rx(struct work_struct *work)
+{
+ struct sci_port *s = container_of(work, struct sci_port, work_rx);
+ struct uart_port *port = &s->port;
+ struct dma_async_tx_descriptor *desc;
+ int new;
+
+ if (s->active_rx == s->cookie_rx[0]) {
+ new = 0;
+ } else if (s->active_rx == s->cookie_rx[1]) {
+ new = 1;
+ } else {
+ dev_err(port->dev, "cookie %d not found!\n", s->active_rx);
+ return;
+ }
+ desc = s->desc_rx[new];
+
+ if (dma_async_is_tx_complete(s->chan_rx, s->active_rx, NULL, NULL) !=
+ DMA_SUCCESS) {
+ /* Handle incomplete DMA receive */
+ struct tty_struct *tty = port->state->port.tty;
+ struct dma_chan *chan = s->chan_rx;
+ struct sh_desc *sh_desc = container_of(desc, struct sh_desc,
+ async_tx);
+ unsigned long flags;
+ int count;
+
+ chan->device->device_terminate_all(chan);
+ dev_dbg(port->dev, "Read %u bytes with cookie %d\n",
+ sh_desc->partial, sh_desc->cookie);
+
+ spin_lock_irqsave(&port->lock, flags);
+ count = sci_dma_rx_push(s, tty, sh_desc->partial);
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ if (count)
+ tty_flip_buffer_push(tty);
+
+ sci_submit_rx(s);
+
+ return;
+ }
+
+ s->cookie_rx[new] = desc->tx_submit(desc);
+ if (s->cookie_rx[new] < 0) {
+ dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
+ sci_rx_dma_release(s, true);
+ return;
+ }
+
+ dev_dbg(port->dev, "%s: cookie %d #%d\n", __func__,
+ s->cookie_rx[new], new);
+
+ s->active_rx = s->cookie_rx[!new];
+}
+
+static void work_fn_tx(struct work_struct *work)
+{
+ struct sci_port *s = container_of(work, struct sci_port, work_tx);
+ struct dma_async_tx_descriptor *desc;
+ struct dma_chan *chan = s->chan_tx;
+ struct uart_port *port = &s->port;
+ struct circ_buf *xmit = &port->state->xmit;
+ struct scatterlist *sg = &s->sg_tx;
+
+ /*
+ * DMA is idle now.
+ * Port xmit buffer is already mapped, and it is one page... Just adjust
+ * offsets and lengths. Since it is a circular buffer, we have to
+ * transmit till the end, and then the rest. Take the port lock to get a
+ * consistent xmit buffer state.
+ */
+ spin_lock_irq(&port->lock);
+ sg->offset = xmit->tail & (UART_XMIT_SIZE - 1);
+ sg->dma_address = (sg_dma_address(sg) & ~(UART_XMIT_SIZE - 1)) +
+ sg->offset;
+ sg->length = min((int)CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE),
+ CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE));
+ sg->dma_length = sg->length;
+ spin_unlock_irq(&port->lock);
+
+ BUG_ON(!sg->length);
+
+ desc = chan->device->device_prep_slave_sg(chan,
+ sg, s->sg_len_tx, DMA_TO_DEVICE,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc) {
+ /* switch to PIO */
+ sci_tx_dma_release(s, true);
+ return;
+ }
+
+ dma_sync_sg_for_device(port->dev, sg, 1, DMA_TO_DEVICE);
+
+ spin_lock_irq(&port->lock);
+ s->desc_tx = desc;
+ desc->callback = sci_dma_tx_complete;
+ desc->callback_param = s;
+ spin_unlock_irq(&port->lock);
+ s->cookie_tx = desc->tx_submit(desc);
+ if (s->cookie_tx < 0) {
+ dev_warn(port->dev, "Failed submitting Tx DMA descriptor\n");
+ /* switch to PIO */
+ sci_tx_dma_release(s, true);
+ return;
+ }
+
+ dev_dbg(port->dev, "%s: %p: %d...%d, cookie %d\n", __func__,
+ xmit->buf, xmit->tail, xmit->head, s->cookie_tx);
+
+ dma_async_issue_pending(chan);
+}
+#endif
+