From 08f738be88bb7a0163afd810a19b9cb13c79808f Mon Sep 17 00:00:00 2001 From: Elen Song Date: Mon, 22 Jul 2013 16:30:26 +0800 Subject: [PATCH] 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 Signed-off-by: Ludovic Desroches Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 210 +++++++++++++++++++++++++++++- 1 file changed, 206 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index b56123d3affe..13c1d3170119 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -143,9 +143,15 @@ struct atmel_uart_port { short pdc_rx_idx; /* current PDC RX buffer */ struct atmel_dma_buffer pdc_rx[2]; /* PDC receier */ + bool use_dma_tx; /* enable DMA transmitter */ bool use_pdc_tx; /* enable PDC transmitter */ struct atmel_dma_buffer pdc_tx; /* PDC transmitter */ + spinlock_t lock_tx; /* port lock */ + struct dma_chan *chan_tx; + struct dma_async_tx_descriptor *desc_tx; + dma_cookie_t cookie_tx; + struct scatterlist sg_tx; struct tasklet_struct tasklet; unsigned int irq_status; unsigned int irq_status_prev; @@ -211,6 +217,13 @@ static bool atmel_use_pdc_tx(struct uart_port *port) } #endif +static bool atmel_use_dma_tx(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + + return atmel_port->use_dma_tx; +} + /* Enable or disable the rs485 support */ void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf) { @@ -569,6 +582,182 @@ static void atmel_tx_chars(struct uart_port *port) UART_PUT_IER(port, atmel_port->tx_done_mask); } +static void atmel_complete_tx_dma(void *arg) +{ + struct atmel_uart_port *atmel_port = arg; + struct uart_port *port = &atmel_port->uart; + struct circ_buf *xmit = &port->state->xmit; + struct dma_chan *chan = atmel_port->chan_tx; + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + + if (chan) + dmaengine_terminate_all(chan); + xmit->tail += sg_dma_len(&atmel_port->sg_tx); + xmit->tail &= UART_XMIT_SIZE - 1; + + port->icount.tx += sg_dma_len(&atmel_port->sg_tx); + + spin_lock_irq(&atmel_port->lock_tx); + async_tx_ack(atmel_port->desc_tx); + atmel_port->cookie_tx = -EINVAL; + atmel_port->desc_tx = NULL; + spin_unlock_irq(&atmel_port->lock_tx); + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); + + /* Do we really need this? */ + if (!uart_circ_empty(xmit)) + tasklet_schedule(&atmel_port->tasklet); + + spin_unlock_irqrestore(&port->lock, flags); +} + +static void atmel_release_tx_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + struct dma_chan *chan = atmel_port->chan_tx; + + if (chan) { + dmaengine_terminate_all(chan); + dma_release_channel(chan); + dma_unmap_sg(port->dev, &atmel_port->sg_tx, 1, + DMA_MEM_TO_DEV); + } + + atmel_port->desc_tx = NULL; + atmel_port->chan_tx = NULL; + atmel_port->cookie_tx = -EINVAL; +} + +/* + * Called from tasklet with TXRDY interrupt is disabled. + */ +static void atmel_tx_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + struct circ_buf *xmit = &port->state->xmit; + struct dma_chan *chan = atmel_port->chan_tx; + struct dma_async_tx_descriptor *desc; + struct scatterlist *sg = &atmel_port->sg_tx; + + /* Make sure we have an idle channel */ + if (atmel_port->desc_tx != NULL) + return; + + if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) { + /* + * 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. + */ + sg->offset = xmit->tail & (UART_XMIT_SIZE - 1); + sg_dma_address(sg) = (sg_dma_address(sg) & + ~(UART_XMIT_SIZE - 1)) + + sg->offset; + sg_dma_len(sg) = CIRC_CNT_TO_END(xmit->head, + xmit->tail, + UART_XMIT_SIZE); + BUG_ON(!sg_dma_len(sg)); + + desc = dmaengine_prep_slave_sg(chan, + sg, + 1, + DMA_MEM_TO_DEV, + DMA_PREP_INTERRUPT | + DMA_CTRL_ACK); + if (!desc) { + dev_err(port->dev, "Failed to send via dma!\n"); + return; + } + + dma_sync_sg_for_device(port->dev, sg, 1, DMA_MEM_TO_DEV); + + atmel_port->desc_tx = desc; + desc->callback = atmel_complete_tx_dma; + desc->callback_param = atmel_port; + atmel_port->cookie_tx = dmaengine_submit(desc); + + } else { + if (atmel_port->rs485.flags & SER_RS485_ENABLED) { + /* DMA done, stop TX, start RX for RS485 */ + atmel_start_rx(port); + } + } + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); +} + +static int atmel_prepare_tx_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + dma_cap_mask_t mask; + struct dma_slave_config config; + int ret, nent; + + dma_cap_zero(mask); + dma_cap_set(DMA_SLAVE, mask); + + atmel_port->chan_tx = dma_request_slave_channel(port->dev, "tx"); + if (atmel_port->chan_tx == NULL) + goto chan_err; + dev_info(port->dev, "using %s for tx DMA transfers\n", + dma_chan_name(atmel_port->chan_tx)); + + spin_lock_init(&atmel_port->lock_tx); + sg_init_table(&atmel_port->sg_tx, 1); + /* UART circular tx buffer is an aligned page. */ + BUG_ON((int)port->state->xmit.buf & ~PAGE_MASK); + sg_set_page(&atmel_port->sg_tx, + virt_to_page(port->state->xmit.buf), + UART_XMIT_SIZE, + (int)port->state->xmit.buf & ~PAGE_MASK); + nent = dma_map_sg(port->dev, + &atmel_port->sg_tx, + 1, + DMA_MEM_TO_DEV); + + if (!nent) { + dev_dbg(port->dev, "need to release resource of dma\n"); + goto chan_err; + } else { + dev_dbg(port->dev, "%s: mapped %d@%p to %x\n", __func__, + sg_dma_len(&atmel_port->sg_tx), + port->state->xmit.buf, + sg_dma_address(&atmel_port->sg_tx)); + } + + /* Configure the slave DMA */ + memset(&config, 0, sizeof(config)); + config.direction = DMA_MEM_TO_DEV; + config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + config.dst_addr = port->mapbase + ATMEL_US_THR; + + ret = dmaengine_device_control(atmel_port->chan_tx, + DMA_SLAVE_CONFIG, + (unsigned long)&config); + if (ret) { + dev_err(port->dev, "DMA tx slave configuration failed\n"); + goto chan_err; + } + + return 0; + +chan_err: + dev_err(port->dev, "TX channel not available, switch to pio\n"); + atmel_port->use_dma_tx = 0; + if (atmel_port->chan_tx) + atmel_release_tx_dma(port); + return -EINVAL; +} + /* * receive interrupt handler. */ @@ -997,7 +1186,11 @@ static void atmel_set_ops(struct uart_port *port) atmel_port->release_rx = NULL; } - if (atmel_use_pdc_tx(port)) { + if (atmel_use_dma_tx(port)) { + atmel_port->prepare_tx = &atmel_prepare_tx_dma; + atmel_port->schedule_tx = &atmel_tx_dma; + atmel_port->release_tx = &atmel_release_tx_dma; + } else if (atmel_use_pdc_tx(port)) { atmel_port->prepare_tx = &atmel_prepare_tx_pdc; atmel_port->schedule_tx = &atmel_tx_pdc; atmel_port->release_tx = &atmel_release_tx_pdc; @@ -1488,10 +1681,18 @@ static void atmel_of_init_port(struct atmel_uart_port *atmel_port, else atmel_port->use_pdc_rx = false; - if (of_get_property(np, "atmel,use-dma-tx", NULL)) - atmel_port->use_pdc_tx = true; - else + if (of_get_property(np, "atmel,use-dma-tx", NULL)) { + if (of_get_property(np, "dmas", NULL)) { + atmel_port->use_dma_tx = true; + atmel_port->use_pdc_tx = false; + } else { + atmel_port->use_dma_tx = false; + atmel_port->use_pdc_tx = true; + } + } else { + atmel_port->use_dma_tx = false; atmel_port->use_pdc_tx = false; + } /* rs485 properties */ if (of_property_read_u32_array(np, "rs485-rts-delay", @@ -1525,6 +1726,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port, } else { atmel_port->use_pdc_rx = pdata->use_dma_rx; atmel_port->use_pdc_tx = pdata->use_dma_tx; + atmel_port->use_dma_tx = false; atmel_port->rs485 = pdata->rs485; } -- 2.30.2