struct uart_8250_port *up =
container_of(port, struct uart_8250_port, port);
- if (!(up->ier & UART_IER_THRI)) {
+ if (up->dma && !serial8250_tx_dma(up)) {
+ return;
+ } else if (!(up->ier & UART_IER_THRI)) {
up->ier |= UART_IER_THRI;
serial_port_out(port, UART_IER, up->ier);
unsigned long flags;
struct uart_8250_port *up =
container_of(port, struct uart_8250_port, port);
+ int dma_err = 0;
if (iir & UART_IIR_NO_INT)
return 0;
DEBUG_INTR("status = %x...", status);
- if (status & (UART_LSR_DR | UART_LSR_BI))
- status = serial8250_rx_chars(up, status);
+ if (status & (UART_LSR_DR | UART_LSR_BI)) {
+ if (up->dma)
+ dma_err = serial8250_rx_dma(up, iir);
+
+ if (!up->dma || dma_err)
+ status = serial8250_rx_chars(up, status);
+ }
serial8250_modem_status(up);
if (status & UART_LSR_THRE)
serial8250_tx_chars(up);
up->lsr_saved_flags = 0;
up->msr_saved_flags = 0;
+ /*
+ * Request DMA channels for both RX and TX.
+ */
+ if (up->dma) {
+ retval = serial8250_request_dma(up);
+ if (retval) {
+ pr_warn_ratelimited("ttyS%d - failed to request DMA\n",
+ serial_index(port));
+ up->dma = NULL;
+ }
+ }
+
/*
* Finally, enable interrupts. Note: Modem status interrupts
* are set via set_termios(), which will be occurring imminently
up->ier = 0;
serial_port_out(port, UART_IER, 0);
+ if (up->dma)
+ serial8250_release_dma(up);
+
spin_lock_irqsave(&port->lock, flags);
if (port->flags & UPF_FOURPORT) {
/* reset interrupts on the AST Fourport board */
uart->dl_read = up->dl_read;
if (up->dl_write)
uart->dl_write = up->dl_write;
+ if (up->dma)
+ uart->dma = up->dma;
if (serial8250_isa_config != NULL)
serial8250_isa_config(0, &uart->port,
--- /dev/null
+/*
+ * 8250_dma.c - DMA Engine API support for 8250.c
+ *
+ * Copyright (C) 2013 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_reg.h>
+#include <linux/dma-mapping.h>
+
+#include "8250.h"
+
+static void __dma_tx_complete(void *param)
+{
+ struct uart_8250_port *p = param;
+ struct uart_8250_dma *dma = p->dma;
+ struct circ_buf *xmit = &p->port.state->xmit;
+
+ dma->tx_running = 0;
+
+ dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr,
+ UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+ xmit->tail += dma->tx_size;
+ xmit->tail &= UART_XMIT_SIZE - 1;
+ p->port.icount.tx += dma->tx_size;
+
+ if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+ uart_write_wakeup(&p->port);
+
+ if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) {
+ serial8250_tx_dma(p);
+ uart_write_wakeup(&p->port);
+ }
+}
+
+static void __dma_rx_complete(void *param)
+{
+ struct uart_8250_port *p = param;
+ struct uart_8250_dma *dma = p->dma;
+ struct tty_struct *tty = p->port.state->port.tty;
+ struct dma_tx_state state;
+
+ dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
+ dma->rx_size, DMA_FROM_DEVICE);
+
+ dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+ dmaengine_terminate_all(dma->rxchan);
+
+ tty_insert_flip_string(tty, dma->rx_buf, dma->rx_size - state.residue);
+ p->port.icount.rx += dma->rx_size - state.residue;
+
+ tty_flip_buffer_push(tty);
+}
+
+int serial8250_tx_dma(struct uart_8250_port *p)
+{
+ struct uart_8250_dma *dma = p->dma;
+ struct circ_buf *xmit = &p->port.state->xmit;
+ struct dma_async_tx_descriptor *desc;
+
+ if (dma->tx_running) {
+ uart_write_wakeup(&p->port);
+ return -EBUSY;
+ }
+
+ dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+ desc = dmaengine_prep_slave_single(dma->txchan,
+ dma->tx_addr + xmit->tail,
+ dma->tx_size, DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc)
+ return -EBUSY;
+
+ dma->tx_running = 1;
+
+ desc->callback = __dma_tx_complete;
+ desc->callback_param = p;
+
+ dma->tx_cookie = dmaengine_submit(desc);
+
+ dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
+ UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+ dma_async_issue_pending(dma->txchan);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(serial8250_tx_dma);
+
+int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
+{
+ struct uart_8250_dma *dma = p->dma;
+ struct dma_async_tx_descriptor *desc;
+ struct dma_tx_state state;
+ int dma_status;
+
+ /*
+ * If RCVR FIFO trigger level was not reached, complete the transfer and
+ * let 8250.c copy the remaining data.
+ */
+ if ((iir & 0x3f) == UART_IIR_RX_TIMEOUT) {
+ dma_status = dmaengine_tx_status(dma->rxchan, dma->rx_cookie,
+ &state);
+ if (dma_status == DMA_IN_PROGRESS) {
+ dmaengine_pause(dma->rxchan);
+ __dma_rx_complete(p);
+ }
+ return -ETIMEDOUT;
+ }
+
+ 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;
+
+ 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;
+}
+EXPORT_SYMBOL_GPL(serial8250_rx_dma);
+
+int serial8250_request_dma(struct uart_8250_port *p)
+{
+ struct uart_8250_dma *dma = p->dma;
+ dma_cap_mask_t mask;
+
+ dma->rxconf.src_addr = p->port.mapbase + UART_RX;
+ dma->txconf.dst_addr = p->port.mapbase + UART_TX;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
+
+ /* Get a channel for RX */
+ dma->rxchan = dma_request_channel(mask, dma->fn, dma->rx_param);
+ if (!dma->rxchan)
+ return -ENODEV;
+
+ dmaengine_slave_config(dma->rxchan, &dma->rxconf);
+
+ /* Get a channel for TX */
+ dma->txchan = dma_request_channel(mask, dma->fn, dma->tx_param);
+ if (!dma->txchan) {
+ dma_release_channel(dma->rxchan);
+ return -ENODEV;
+ }
+
+ dmaengine_slave_config(dma->txchan, &dma->txconf);
+
+ /* RX buffer */
+ if (!dma->rx_size)
+ dma->rx_size = PAGE_SIZE;
+
+ dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
+ &dma->rx_addr, GFP_KERNEL);
+ if (!dma->rx_buf) {
+ dma_release_channel(dma->rxchan);
+ dma_release_channel(dma->txchan);
+ return -ENOMEM;
+ }
+
+ /* TX buffer */
+ dma->tx_addr = dma_map_single(dma->txchan->device->dev,
+ p->port.state->xmit.buf,
+ UART_XMIT_SIZE,
+ DMA_TO_DEVICE);
+
+ dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(serial8250_request_dma);
+
+void serial8250_release_dma(struct uart_8250_port *p)
+{
+ struct uart_8250_dma *dma = p->dma;
+
+ if (!dma)
+ return;
+
+ /* Release RX resources */
+ dmaengine_terminate_all(dma->rxchan);
+ dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
+ dma->rx_addr);
+ dma_release_channel(dma->rxchan);
+ dma->rxchan = NULL;
+
+ /* Release TX resources */
+ dmaengine_terminate_all(dma->txchan);
+ dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
+ UART_XMIT_SIZE, DMA_TO_DEVICE);
+ dma_release_channel(dma->txchan);
+ dma->txchan = NULL;
+ dma->tx_running = 0;
+
+ dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
+}
+EXPORT_SYMBOL_GPL(serial8250_release_dma);
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