diff options
| -rw-r--r-- | drivers/tty/serial/8250/8250_omap.c | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 5f183d197dfa..1659858e595a 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -619,6 +619,102 @@ static void omap_8250_unthrottle(struct uart_port *port) } #ifdef CONFIG_SERIAL_8250_DMA +static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir); + +static void __dma_rx_do_complete(struct uart_8250_port *p, bool error) +{ + struct uart_8250_dma *dma = p->dma; + struct tty_port *tty_port = &p->port.state->port; + struct dma_tx_state state; + int count; + + dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr, + dma->rx_size, DMA_FROM_DEVICE); + + dma->rx_running = 0; + dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); + dmaengine_terminate_all(dma->rxchan); + + count = dma->rx_size - state.residue; + + tty_insert_flip_string(tty_port, dma->rx_buf, count); + p->port.icount.rx += count; + if (!error) + omap_8250_rx_dma(p, 0); + + tty_flip_buffer_push(tty_port); +} + +static void __dma_rx_complete(void *param) +{ + __dma_rx_do_complete(param, false); +} + +static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir) +{ + struct uart_8250_dma *dma = p->dma; + struct dma_async_tx_descriptor *desc; + + switch (iir & 0x3f) { + case UART_IIR_RLSI: + /* 8250_core handles errors and break interrupts */ + if (dma->rx_running) { + dmaengine_pause(dma->rxchan); + __dma_rx_do_complete(p, true); + } + return -EIO; + case UART_IIR_RX_TIMEOUT: + /* + * If RCVR FIFO trigger level was not reached, complete the + * transfer and let 8250_core copy the remaining data. + */ + if (dma->rx_running) { + dmaengine_pause(dma->rxchan); + __dma_rx_do_complete(p, true); + } + return -ETIMEDOUT; + case UART_IIR_RDI: + /* + * The OMAP UART is a special BEAST. If we receive RDI we _have_ + * a DMA transfer programmed but it didn't work. One reason is + * that we were too slow and there were too many bytes in the + * FIFO, the UART counted wrong and never kicked the DMA engine + * to do anything. That means once we receive RDI on OMAP then + * the DMA won't do anything soon so we have to cancel the DMA + * transfer and purge the FIFO manually. + */ + if (dma->rx_running) { + dmaengine_pause(dma->rxchan); + __dma_rx_do_complete(p, true); + } + return -ETIMEDOUT; + + default: + break; + } + + if (dma->rx_running) + return 0; + + desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr, + dma->rx_size, DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!desc) + return -EBUSY; + + dma->rx_running = 1; + desc->callback = __dma_rx_complete; + desc->callback_param = p; + + dma->rx_cookie = dmaengine_submit(desc); + + dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr, + dma->rx_size, DMA_FROM_DEVICE); + + dma_async_issue_pending(dma->rxchan); + return 0; +} + static int omap_8250_tx_dma(struct uart_8250_port *p); static void omap_8250_dma_tx_complete(void *param) |