diff options
| -rw-r--r-- | drivers/tty/serial/atmel_serial.c | 224 |
1 files changed, 220 insertions, 4 deletions
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 13c1d31..eaf7dc7 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -139,6 +139,7 @@ struct atmel_uart_port { u32 backup_imr; /* IMR saved during suspend */ int break_active; /* break being received */ + bool use_dma_rx; /* enable DMA receiver */ bool use_pdc_rx; /* enable PDC receiver */ short pdc_rx_idx; /* current PDC RX buffer */ struct atmel_dma_buffer pdc_rx[2]; /* PDC receier */ @@ -148,10 +149,15 @@ struct atmel_uart_port { struct atmel_dma_buffer pdc_tx; /* PDC transmitter */ spinlock_t lock_tx; /* port lock */ + spinlock_t lock_rx; /* port lock */ struct dma_chan *chan_tx; + struct dma_chan *chan_rx; struct dma_async_tx_descriptor *desc_tx; + struct dma_async_tx_descriptor *desc_rx; dma_cookie_t cookie_tx; + dma_cookie_t cookie_rx; struct scatterlist sg_tx; + struct scatterlist sg_rx; struct tasklet_struct tasklet; unsigned int irq_status; unsigned int irq_status_prev; @@ -224,6 +230,13 @@ static bool atmel_use_dma_tx(struct uart_port *port) return atmel_port->use_dma_tx; } +static bool atmel_use_dma_rx(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + + return atmel_port->use_dma_rx; +} + /* Enable or disable the rs485 support */ void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf) { @@ -758,6 +771,184 @@ chan_err: return -EINVAL; } +static void atmel_flip_buffer_rx_dma(struct uart_port *port, + char *buf, size_t count) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + struct tty_port *tport = &port->state->port; + + dma_sync_sg_for_cpu(port->dev, + &atmel_port->sg_rx, + 1, + DMA_DEV_TO_MEM); + + tty_insert_flip_string(tport, buf, count); + + dma_sync_sg_for_device(port->dev, + &atmel_port->sg_rx, + 1, + DMA_DEV_TO_MEM); + /* + * Drop the lock here since it might end up calling + * uart_start(), which takes the lock. + */ + spin_unlock(&port->lock); + tty_flip_buffer_push(tport); + spin_lock(&port->lock); +} + +static void atmel_complete_rx_dma(void *arg) +{ + struct uart_port *port = arg; + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + + tasklet_schedule(&atmel_port->tasklet); +} + +static void atmel_release_rx_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + struct dma_chan *chan = atmel_port->chan_rx; + + if (chan) { + dmaengine_terminate_all(chan); + dma_release_channel(chan); + dma_unmap_sg(port->dev, &atmel_port->sg_rx, 1, + DMA_DEV_TO_MEM); + } + + atmel_port->desc_rx = NULL; + atmel_port->chan_rx = NULL; + atmel_port->cookie_rx = -EINVAL; +} + +static void atmel_rx_from_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + struct circ_buf *ring = &atmel_port->rx_ring; + struct dma_chan *chan = atmel_port->chan_rx; + struct dma_tx_state state; + enum dma_status dmastat; + size_t pending, count; + + + /* Reset the UART timeout early so that we don't miss one */ + UART_PUT_CR(port, ATMEL_US_STTTO); + dmastat = dmaengine_tx_status(chan, + atmel_port->cookie_rx, + &state); + /* Restart a new tasklet if DMA status is error */ + if (dmastat == DMA_ERROR) { + dev_dbg(port->dev, "Get residue error, restart tasklet\n"); + UART_PUT_IER(port, ATMEL_US_TIMEOUT); + tasklet_schedule(&atmel_port->tasklet); + return; + } + /* current transfer size should no larger than dma buffer */ + pending = sg_dma_len(&atmel_port->sg_rx) - state.residue; + BUG_ON(pending > sg_dma_len(&atmel_port->sg_rx)); + + /* + * This will take the chars we have so far, + * ring->head will record the transfer size, only new bytes come + * will insert into the framework. + */ + if (pending > ring->head) { + count = pending - ring->head; + + atmel_flip_buffer_rx_dma(port, ring->buf + ring->head, count); + + ring->head += count; + if (ring->head == sg_dma_len(&atmel_port->sg_rx)) + ring->head = 0; + + port->icount.rx += count; + } + + UART_PUT_IER(port, ATMEL_US_TIMEOUT); +} + +static int atmel_prepare_rx_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + struct dma_async_tx_descriptor *desc; + dma_cap_mask_t mask; + struct dma_slave_config config; + struct circ_buf *ring; + int ret, nent; + + ring = &atmel_port->rx_ring; + + dma_cap_zero(mask); + dma_cap_set(DMA_CYCLIC, mask); + + atmel_port->chan_rx = dma_request_slave_channel(port->dev, "rx"); + if (atmel_port->chan_rx == NULL) + goto chan_err; + dev_info(port->dev, "using %s for rx DMA transfers\n", + dma_chan_name(atmel_port->chan_rx)); + + spin_lock_init(&atmel_port->lock_rx); + sg_init_table(&atmel_port->sg_rx, 1); + /* UART circular rx buffer is an aligned page. */ + BUG_ON((int)port->state->xmit.buf & ~PAGE_MASK); + sg_set_page(&atmel_port->sg_rx, + virt_to_page(ring->buf), + ATMEL_SERIAL_RINGSIZE, + (int)ring->buf & ~PAGE_MASK); + nent = dma_map_sg(port->dev, + &atmel_port->sg_rx, + 1, + DMA_DEV_TO_MEM); + + 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_rx), + ring->buf, + sg_dma_address(&atmel_port->sg_rx)); + } + + /* Configure the slave DMA */ + memset(&config, 0, sizeof(config)); + config.direction = DMA_DEV_TO_MEM; + config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + config.src_addr = port->mapbase + ATMEL_US_RHR; + + ret = dmaengine_device_control(atmel_port->chan_rx, + DMA_SLAVE_CONFIG, + (unsigned long)&config); + if (ret) { + dev_err(port->dev, "DMA rx slave configuration failed\n"); + goto chan_err; + } + /* + * Prepare a cyclic dma transfer, assign 2 descriptors, + * each one is half ring buffer size + */ + desc = dmaengine_prep_dma_cyclic(atmel_port->chan_rx, + sg_dma_address(&atmel_port->sg_rx), + sg_dma_len(&atmel_port->sg_rx), + sg_dma_len(&atmel_port->sg_rx)/2, + DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); + desc->callback = atmel_complete_rx_dma; + desc->callback_param = port; + atmel_port->desc_rx = desc; + atmel_port->cookie_rx = dmaengine_submit(desc); + + return 0; + +chan_err: + dev_err(port->dev, "RX channel not available, switch to pio\n"); + atmel_port->use_dma_rx = 0; + if (atmel_port->chan_rx) + atmel_release_rx_dma(port); + return -EINVAL; +} + /* * receive interrupt handler. */ @@ -785,6 +976,13 @@ atmel_handle_receive(struct uart_port *port, unsigned int pending) atmel_pdc_rxerr(port, pending); } + if (atmel_use_dma_rx(port)) { + if (pending & ATMEL_US_TIMEOUT) { + UART_PUT_IDR(port, ATMEL_US_TIMEOUT); + tasklet_schedule(&atmel_port->tasklet); + } + } + /* Interrupt receive */ if (pending & ATMEL_US_RXRDY) atmel_rx_chars(port); @@ -1176,7 +1374,11 @@ static void atmel_set_ops(struct uart_port *port) { struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); - if (atmel_use_pdc_rx(port)) { + if (atmel_use_dma_rx(port)) { + atmel_port->prepare_rx = &atmel_prepare_rx_dma; + atmel_port->schedule_rx = &atmel_rx_from_dma; + atmel_port->release_rx = &atmel_release_rx_dma; + } else if (atmel_use_pdc_rx(port)) { atmel_port->prepare_rx = &atmel_prepare_rx_pdc; atmel_port->schedule_rx = &atmel_rx_from_pdc; atmel_port->release_rx = &atmel_release_rx_pdc; @@ -1272,6 +1474,11 @@ static int atmel_startup(struct uart_port *port) UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT); /* enable PDC controller */ UART_PUT_PTCR(port, ATMEL_PDC_RXTEN); + } else if (atmel_use_dma_rx(port)) { + UART_PUT_RTOR(port, PDC_RX_TIMEOUT); + UART_PUT_CR(port, ATMEL_US_STTTO); + + UART_PUT_IER(port, ATMEL_US_TIMEOUT); } else { /* enable receive only */ UART_PUT_IER(port, ATMEL_US_RXRDY); @@ -1676,10 +1883,18 @@ static void atmel_of_init_port(struct atmel_uart_port *atmel_port, u32 rs485_delay[2]; /* DMA/PDC usage specification */ - if (of_get_property(np, "atmel,use-dma-rx", NULL)) - atmel_port->use_pdc_rx = true; - else + if (of_get_property(np, "atmel,use-dma-rx", NULL)) { + if (of_get_property(np, "dmas", NULL)) { + atmel_port->use_dma_rx = true; + atmel_port->use_pdc_rx = false; + } else { + atmel_port->use_dma_rx = false; + atmel_port->use_pdc_rx = true; + } + } else { + atmel_port->use_dma_rx = false; atmel_port->use_pdc_rx = false; + } if (of_get_property(np, "atmel,use-dma-tx", NULL)) { if (of_get_property(np, "dmas", NULL)) { @@ -1726,6 +1941,7 @@ 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_rx = false; atmel_port->use_dma_tx = false; atmel_port->rs485 = pdata->rs485; } |
