forked from Minki/linux
serial: at91: add tx dma support
Request a slave dma channel for tx dma use. Tx dma will setup a single transfer, when transfer complete, it will call atmel_complete_tx_dma to do finish stuff. Signed-off-by: Elen Song <elen.song@atmel.com> Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Elen Song
Greg Kroah-Hartman
parent
a930e52875
commit
08f738be88
@ -143,9 +143,15 @@ struct atmel_uart_port {
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short pdc_rx_idx; /* current PDC RX buffer */
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struct atmel_dma_buffer pdc_rx[2]; /* PDC receier */
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bool use_dma_tx; /* enable DMA transmitter */
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bool use_pdc_tx; /* enable PDC transmitter */
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struct atmel_dma_buffer pdc_tx; /* PDC transmitter */
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spinlock_t lock_tx; /* port lock */
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struct dma_chan *chan_tx;
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struct dma_async_tx_descriptor *desc_tx;
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dma_cookie_t cookie_tx;
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struct scatterlist sg_tx;
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struct tasklet_struct tasklet;
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unsigned int irq_status;
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unsigned int irq_status_prev;
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@ -211,6 +217,13 @@ static bool atmel_use_pdc_tx(struct uart_port *port)
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}
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#endif
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static bool atmel_use_dma_tx(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
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return atmel_port->use_dma_tx;
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}
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/* Enable or disable the rs485 support */
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void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
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{
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@ -569,6 +582,182 @@ static void atmel_tx_chars(struct uart_port *port)
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UART_PUT_IER(port, atmel_port->tx_done_mask);
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}
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static void atmel_complete_tx_dma(void *arg)
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{
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struct atmel_uart_port *atmel_port = arg;
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struct uart_port *port = &atmel_port->uart;
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struct circ_buf *xmit = &port->state->xmit;
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struct dma_chan *chan = atmel_port->chan_tx;
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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if (chan)
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dmaengine_terminate_all(chan);
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xmit->tail += sg_dma_len(&atmel_port->sg_tx);
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xmit->tail &= UART_XMIT_SIZE - 1;
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port->icount.tx += sg_dma_len(&atmel_port->sg_tx);
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spin_lock_irq(&atmel_port->lock_tx);
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async_tx_ack(atmel_port->desc_tx);
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atmel_port->cookie_tx = -EINVAL;
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atmel_port->desc_tx = NULL;
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spin_unlock_irq(&atmel_port->lock_tx);
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if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
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uart_write_wakeup(port);
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/* Do we really need this? */
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if (!uart_circ_empty(xmit))
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tasklet_schedule(&atmel_port->tasklet);
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spin_unlock_irqrestore(&port->lock, flags);
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}
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static void atmel_release_tx_dma(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
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struct dma_chan *chan = atmel_port->chan_tx;
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if (chan) {
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dmaengine_terminate_all(chan);
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dma_release_channel(chan);
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dma_unmap_sg(port->dev, &atmel_port->sg_tx, 1,
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DMA_MEM_TO_DEV);
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}
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atmel_port->desc_tx = NULL;
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atmel_port->chan_tx = NULL;
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atmel_port->cookie_tx = -EINVAL;
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}
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/*
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* Called from tasklet with TXRDY interrupt is disabled.
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*/
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static void atmel_tx_dma(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
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struct circ_buf *xmit = &port->state->xmit;
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struct dma_chan *chan = atmel_port->chan_tx;
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struct dma_async_tx_descriptor *desc;
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struct scatterlist *sg = &atmel_port->sg_tx;
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/* Make sure we have an idle channel */
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if (atmel_port->desc_tx != NULL)
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return;
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if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
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/*
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* DMA is idle now.
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* Port xmit buffer is already mapped,
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* and it is one page... Just adjust
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* offsets and lengths. Since it is a circular buffer,
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* we have to transmit till the end, and then the rest.
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* Take the port lock to get a
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* consistent xmit buffer state.
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*/
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sg->offset = xmit->tail & (UART_XMIT_SIZE - 1);
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sg_dma_address(sg) = (sg_dma_address(sg) &
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~(UART_XMIT_SIZE - 1))
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+ sg->offset;
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sg_dma_len(sg) = CIRC_CNT_TO_END(xmit->head,
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xmit->tail,
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UART_XMIT_SIZE);
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BUG_ON(!sg_dma_len(sg));
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desc = dmaengine_prep_slave_sg(chan,
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sg,
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1,
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DMA_MEM_TO_DEV,
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DMA_PREP_INTERRUPT |
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DMA_CTRL_ACK);
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if (!desc) {
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dev_err(port->dev, "Failed to send via dma!\n");
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return;
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}
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dma_sync_sg_for_device(port->dev, sg, 1, DMA_MEM_TO_DEV);
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atmel_port->desc_tx = desc;
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desc->callback = atmel_complete_tx_dma;
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desc->callback_param = atmel_port;
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atmel_port->cookie_tx = dmaengine_submit(desc);
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} else {
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if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
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/* DMA done, stop TX, start RX for RS485 */
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atmel_start_rx(port);
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}
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}
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if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
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uart_write_wakeup(port);
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}
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static int atmel_prepare_tx_dma(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
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dma_cap_mask_t mask;
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struct dma_slave_config config;
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int ret, nent;
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dma_cap_zero(mask);
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dma_cap_set(DMA_SLAVE, mask);
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atmel_port->chan_tx = dma_request_slave_channel(port->dev, "tx");
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if (atmel_port->chan_tx == NULL)
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goto chan_err;
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dev_info(port->dev, "using %s for tx DMA transfers\n",
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dma_chan_name(atmel_port->chan_tx));
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spin_lock_init(&atmel_port->lock_tx);
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sg_init_table(&atmel_port->sg_tx, 1);
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/* UART circular tx buffer is an aligned page. */
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BUG_ON((int)port->state->xmit.buf & ~PAGE_MASK);
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sg_set_page(&atmel_port->sg_tx,
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virt_to_page(port->state->xmit.buf),
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UART_XMIT_SIZE,
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(int)port->state->xmit.buf & ~PAGE_MASK);
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nent = dma_map_sg(port->dev,
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&atmel_port->sg_tx,
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1,
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DMA_MEM_TO_DEV);
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if (!nent) {
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dev_dbg(port->dev, "need to release resource of dma\n");
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goto chan_err;
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} else {
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dev_dbg(port->dev, "%s: mapped %d@%p to %x\n", __func__,
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sg_dma_len(&atmel_port->sg_tx),
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port->state->xmit.buf,
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sg_dma_address(&atmel_port->sg_tx));
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}
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/* Configure the slave DMA */
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memset(&config, 0, sizeof(config));
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config.direction = DMA_MEM_TO_DEV;
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config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
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config.dst_addr = port->mapbase + ATMEL_US_THR;
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ret = dmaengine_device_control(atmel_port->chan_tx,
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DMA_SLAVE_CONFIG,
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(unsigned long)&config);
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if (ret) {
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dev_err(port->dev, "DMA tx slave configuration failed\n");
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goto chan_err;
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}
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return 0;
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chan_err:
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dev_err(port->dev, "TX channel not available, switch to pio\n");
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atmel_port->use_dma_tx = 0;
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if (atmel_port->chan_tx)
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atmel_release_tx_dma(port);
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return -EINVAL;
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}
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/*
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* receive interrupt handler.
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*/
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@ -997,7 +1186,11 @@ static void atmel_set_ops(struct uart_port *port)
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atmel_port->release_rx = NULL;
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}
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if (atmel_use_pdc_tx(port)) {
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if (atmel_use_dma_tx(port)) {
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atmel_port->prepare_tx = &atmel_prepare_tx_dma;
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atmel_port->schedule_tx = &atmel_tx_dma;
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atmel_port->release_tx = &atmel_release_tx_dma;
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} else if (atmel_use_pdc_tx(port)) {
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atmel_port->prepare_tx = &atmel_prepare_tx_pdc;
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atmel_port->schedule_tx = &atmel_tx_pdc;
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atmel_port->release_tx = &atmel_release_tx_pdc;
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@ -1488,10 +1681,18 @@ static void atmel_of_init_port(struct atmel_uart_port *atmel_port,
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else
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atmel_port->use_pdc_rx = false;
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if (of_get_property(np, "atmel,use-dma-tx", NULL))
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atmel_port->use_pdc_tx = true;
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else
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if (of_get_property(np, "atmel,use-dma-tx", NULL)) {
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if (of_get_property(np, "dmas", NULL)) {
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atmel_port->use_dma_tx = true;
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atmel_port->use_pdc_tx = false;
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} else {
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atmel_port->use_dma_tx = false;
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atmel_port->use_pdc_tx = true;
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}
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} else {
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atmel_port->use_dma_tx = false;
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atmel_port->use_pdc_tx = false;
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}
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/* rs485 properties */
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if (of_property_read_u32_array(np, "rs485-rts-delay",
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@ -1525,6 +1726,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
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} else {
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atmel_port->use_pdc_rx = pdata->use_dma_rx;
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atmel_port->use_pdc_tx = pdata->use_dma_tx;
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atmel_port->use_dma_tx = false;
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atmel_port->rs485 = pdata->rs485;
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}
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