1 files changed, 216 insertions, 0 deletions

diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
new file mode 100644
index 000000000000..b9f7fd28112e
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -0,0 +1,216 @@
+/*
+ * 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_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);
+
+        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;
+
+        tty_flip_buffer_push(tty_port);
+}
+
+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)
+                return -EBUSY;
+
+        dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+        if (!dma->tx_size)
+                return -EINVAL;
+
+        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);