diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 0df2b1c091ae..1912136f7257 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -222,6 +222,9 @@ struct imx_port { struct dma_chan *dma_chan_rx, *dma_chan_tx; struct scatterlist rx_sgl, tx_sgl[2]; void *rx_buf; + struct circ_buf rx_ring; + unsigned int rx_periods; + dma_cookie_t rx_cookie; unsigned int tx_bytes; unsigned int dma_tx_nents; wait_queue_head_t dma_wait; @@ -932,30 +935,6 @@ static void imx_timeout(unsigned long data) } #define RX_BUF_SIZE (PAGE_SIZE) -static void imx_rx_dma_done(struct imx_port *sport) -{ - unsigned long temp; - unsigned long flags; - - spin_lock_irqsave(&sport->port.lock, flags); - - /* re-enable interrupts to get notified when new symbols are incoming */ - temp = readl(sport->port.membase + UCR1); - temp |= UCR1_RRDYEN; - writel(temp, sport->port.membase + UCR1); - - temp = readl(sport->port.membase + UCR2); - temp |= UCR2_ATEN; - writel(temp, sport->port.membase + UCR2); - - sport->dma_is_rxing = 0; - - /* Is the shutdown waiting for us? */ - if (waitqueue_active(&sport->dma_wait)) - wake_up(&sport->dma_wait); - - spin_unlock_irqrestore(&sport->port.lock, flags); -} /* * There are two kinds of RX DMA interrupts(such as in the MX6Q): @@ -972,43 +951,75 @@ static void dma_rx_callback(void *data) struct scatterlist *sgl = &sport->rx_sgl; struct tty_port *port = &sport->port.state->port; struct dma_tx_state state; + struct circ_buf *rx_ring = &sport->rx_ring; enum dma_status status; - unsigned int count; - - /* unmap it first */ - dma_unmap_sg(sport->port.dev, sgl, 1, DMA_FROM_DEVICE); + unsigned int w_bytes = 0; + unsigned int r_bytes; + unsigned int bd_size; status = dmaengine_tx_status(chan, (dma_cookie_t)0, &state); - count = RX_BUF_SIZE - state.residue; - dev_dbg(sport->port.dev, "We get %d bytes.\n", count); - - if (count) { - if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) { - int bytes = tty_insert_flip_string(port, sport->rx_buf, - count); - - if (bytes != count) - sport->port.icount.buf_overrun++; - } - tty_flip_buffer_push(port); - sport->port.icount.rx += count; + if (status == DMA_ERROR) { + dev_err(sport->port.dev, "DMA transaction error.\n"); + return; } - /* - * Restart RX DMA directly if more data is available in order to skip - * the roundtrip through the IRQ handler. If there is some data already - * in the FIFO, DMA needs to be restarted soon anyways. - * - * Otherwise stop the DMA and reactivate FIFO IRQs to restart DMA once - * data starts to arrive again. - */ - if (readl(sport->port.membase + USR2) & USR2_RDR) - start_rx_dma(sport); - else - imx_rx_dma_done(sport); + if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) { + + /* + * The state-residue variable represents the empty space + * relative to the entire buffer. Taking this in consideration + * the head is always calculated base on the buffer total + * length - DMA transaction residue. The UART script from the + * SDMA firmware will jump to the next buffer descriptor, + * once a DMA transaction if finalized (IMX53 RM - A.4.1.2.4). + * Taking this in consideration the tail is always at the + * beginning of the buffer descriptor that contains the head. + */ + + /* Calculate the head */ + rx_ring->head = sg_dma_len(sgl) - state.residue; + + /* Calculate the tail. */ + bd_size = sg_dma_len(sgl) / sport->rx_periods; + rx_ring->tail = ((rx_ring->head-1) / bd_size) * bd_size; + + if (rx_ring->head <= sg_dma_len(sgl) && + rx_ring->head > rx_ring->tail) { + + /* Move data from tail to head */ + r_bytes = rx_ring->head - rx_ring->tail; + + /* CPU claims ownership of RX DMA buffer */ + dma_sync_sg_for_cpu(sport->port.dev, sgl, 1, + DMA_FROM_DEVICE); + + w_bytes = tty_insert_flip_string(port, + sport->rx_buf + rx_ring->tail, r_bytes); + + /* UART retrieves ownership of RX DMA buffer */ + dma_sync_sg_for_device(sport->port.dev, sgl, 1, + DMA_FROM_DEVICE); + + if (w_bytes != r_bytes) + sport->port.icount.buf_overrun++; + + sport->port.icount.rx += w_bytes; + } else { + WARN_ON(rx_ring->head > sg_dma_len(sgl)); + WARN_ON(rx_ring->head <= rx_ring->tail); + } + } + + if (w_bytes) { + tty_flip_buffer_push(port); + dev_dbg(sport->port.dev, "We get %d bytes.\n", w_bytes); + } } +/* RX DMA buffer periods */ +#define RX_DMA_PERIODS 4 + static int start_rx_dma(struct imx_port *sport) { struct scatterlist *sgl = &sport->rx_sgl; @@ -1017,14 +1028,21 @@ static int start_rx_dma(struct imx_port *sport) struct dma_async_tx_descriptor *desc; int ret; + sport->rx_ring.head = 0; + sport->rx_ring.tail = 0; + sport->rx_periods = RX_DMA_PERIODS; + sg_init_one(sgl, sport->rx_buf, RX_BUF_SIZE); ret = dma_map_sg(dev, sgl, 1, DMA_FROM_DEVICE); if (ret == 0) { dev_err(dev, "DMA mapping error for RX.\n"); return -EINVAL; } - desc = dmaengine_prep_slave_sg(chan, sgl, 1, DMA_DEV_TO_MEM, - DMA_PREP_INTERRUPT); + + desc = dmaengine_prep_dma_cyclic(chan, sg_dma_address(sgl), + sg_dma_len(sgl), sg_dma_len(sgl) / sport->rx_periods, + DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT); + if (!desc) { dma_unmap_sg(dev, sgl, 1, DMA_FROM_DEVICE); dev_err(dev, "We cannot prepare for the RX slave dma!\n"); @@ -1034,7 +1052,7 @@ static int start_rx_dma(struct imx_port *sport) desc->callback_param = sport; dev_dbg(dev, "RX: prepare for the DMA.\n"); - dmaengine_submit(desc); + sport->rx_cookie = dmaengine_submit(desc); dma_async_issue_pending(chan); return 0; } @@ -1058,14 +1076,16 @@ static void imx_setup_ufcr(struct imx_port *sport, static void imx_uart_dma_exit(struct imx_port *sport) { if (sport->dma_chan_rx) { + dmaengine_terminate_all(sport->dma_chan_rx); dma_release_channel(sport->dma_chan_rx); sport->dma_chan_rx = NULL; - + sport->rx_cookie = -EINVAL; kfree(sport->rx_buf); sport->rx_buf = NULL; } if (sport->dma_chan_tx) { + dmaengine_terminate_all(sport->dma_chan_tx); dma_release_channel(sport->dma_chan_tx); sport->dma_chan_tx = NULL; } @@ -1103,6 +1123,7 @@ static int imx_uart_dma_init(struct imx_port *sport) ret = -ENOMEM; goto err; } + sport->rx_ring.buf = sport->rx_buf; /* Prepare for TX : */ sport->dma_chan_tx = dma_request_slave_channel(dev, "tx"); @@ -1283,17 +1304,11 @@ static void imx_shutdown(struct uart_port *port) unsigned long flags; if (sport->dma_is_enabled) { - int ret; + sport->dma_is_rxing = 0; + sport->dma_is_txing = 0; + dmaengine_terminate_all(sport->dma_chan_tx); + dmaengine_terminate_all(sport->dma_chan_rx); - /* We have to wait for the DMA to finish. */ - ret = wait_event_interruptible(sport->dma_wait, - !sport->dma_is_rxing && !sport->dma_is_txing); - if (ret != 0) { - sport->dma_is_rxing = 0; - sport->dma_is_txing = 0; - dmaengine_terminate_all(sport->dma_chan_tx); - dmaengine_terminate_all(sport->dma_chan_rx); - } spin_lock_irqsave(&sport->port.lock, flags); imx_stop_tx(port); imx_stop_rx(port);