drivers/tty/serial/8250/8250_dma.c

   1 /*
   2  * 8250_dma.c - DMA Engine API support for 8250.c
   3  *
   4  * Copyright (C) 2013 Intel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11 #include <linux/tty.h>
  12 #include <linux/tty_flip.h>
  13 #include <linux/serial_reg.h>
  14 #include <linux/dma-mapping.h>
  15
  16 #include "8250.h"
  17
  18 static void __dma_tx_complete(void *param)
  19 {
  20         struct uart_8250_port   *p = param;
  21         struct uart_8250_dma    *dma = p->dma;
  22         struct circ_buf         *xmit = &p->port.state->xmit;
  23         unsigned long   flags;
  24         int             ret;
  25
  26         dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr,
  27                                 UART_XMIT_SIZE, DMA_TO_DEVICE);
  28
  29         spin_lock_irqsave(&p->port.lock, flags);
  30
  31         dma->tx_running = 0;
  32
  33         xmit->tail += dma->tx_size;
  34         xmit->tail &= UART_XMIT_SIZE - 1;
  35         p->port.icount.tx += dma->tx_size;
  36
  37         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
  38                 uart_write_wakeup(&p->port);
  39
  40         ret = serial8250_tx_dma(p);
  41         if (ret) {
  42                 dma->tx_err = 1;
  43                 p->ier |= UART_IER_THRI;
  44                 serial_port_out(&p->port, UART_IER, p->ier);
  45         }
  46
  47         spin_unlock_irqrestore(&p->port.lock, flags);
  48 }
  49
  50 static void __dma_rx_complete(void *param)
  51 {
  52         struct uart_8250_port   *p = param;
  53         struct uart_8250_dma    *dma = p->dma;
  54         struct tty_port         *tty_port = &p->port.state->port;
  55         struct dma_tx_state     state;
  56         int                     count;
  57
  58         dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
  59                                 dma->rx_size, DMA_FROM_DEVICE);
  60
  61         dma->rx_running = 0;
  62         dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
  63         dmaengine_terminate_all(dma->rxchan);
  64
  65         count = dma->rx_size - state.residue;
  66
  67         tty_insert_flip_string(tty_port, dma->rx_buf, count);
  68         p->port.icount.rx += count;
  69
  70         tty_flip_buffer_push(tty_port);
  71 }
  72
  73 int serial8250_tx_dma(struct uart_8250_port *p)
  74 {
  75         struct uart_8250_dma            *dma = p->dma;
  76         struct circ_buf                 *xmit = &p->port.state->xmit;
  77         struct dma_async_tx_descriptor  *desc;
  78         int ret;
  79
  80         if (uart_tx_stopped(&p->port) || dma->tx_running ||
  81             uart_circ_empty(xmit))
  82                 return 0;
  83
  84         dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
  85
  86         desc = dmaengine_prep_slave_single(dma->txchan,
  87                                            dma->tx_addr + xmit->tail,
  88                                            dma->tx_size, DMA_MEM_TO_DEV,
  89                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
  90         if (!desc) {
  91                 ret = -EBUSY;
  92                 goto err;
  93         }
  94
  95         dma->tx_running = 1;
  96
  97         desc->callback = __dma_tx_complete;
  98         desc->callback_param = p;
  99
 100         dma->tx_cookie = dmaengine_submit(desc);
 101
 102         dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
 103                                    UART_XMIT_SIZE, DMA_TO_DEVICE);
 104
 105         dma_async_issue_pending(dma->txchan);
 106         if (dma->tx_err) {
 107                 dma->tx_err = 0;
 108                 if (p->ier & UART_IER_THRI) {
 109                         p->ier &= ~UART_IER_THRI;
 110                         serial_out(p, UART_IER, p->ier);
 111                 }
 112         }
 113         return 0;
 114 err:
 115         dma->tx_err = 1;
 116         return ret;
 117 }
 118
 119 int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
 120 {
 121         struct uart_8250_dma            *dma = p->dma;
 122         struct dma_async_tx_descriptor  *desc;
 123
 124         switch (iir & 0x3f) {
 125         case UART_IIR_RLSI:
 126                 /* 8250_core handles errors and break interrupts */
 127                 return -EIO;
 128         case UART_IIR_RX_TIMEOUT:
 129                 /*
 130                  * If RCVR FIFO trigger level was not reached, complete the
 131                  * transfer and let 8250_core copy the remaining data.
 132                  */
 133                 if (dma->rx_running) {
 134                         dmaengine_pause(dma->rxchan);
 135                         __dma_rx_complete(p);
 136                 }
 137                 return -ETIMEDOUT;
 138         default:
 139                 break;
 140         }
 141
 142         if (dma->rx_running)
 143                 return 0;
 144
 145         desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
 146                                            dma->rx_size, DMA_DEV_TO_MEM,
 147                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 148         if (!desc)
 149                 return -EBUSY;
 150
 151         dma->rx_running = 1;
 152         desc->callback = __dma_rx_complete;
 153         desc->callback_param = p;
 154
 155         dma->rx_cookie = dmaengine_submit(desc);
 156
 157         dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr,
 158                                    dma->rx_size, DMA_FROM_DEVICE);
 159
 160         dma_async_issue_pending(dma->rxchan);
 161
 162         return 0;
 163 }
 164
 165 int serial8250_request_dma(struct uart_8250_port *p)
 166 {
 167         struct uart_8250_dma    *dma = p->dma;
 168         dma_cap_mask_t          mask;
 169
 170         /* Default slave configuration parameters */
 171         dma->rxconf.direction           = DMA_DEV_TO_MEM;
 172         dma->rxconf.src_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 173         dma->rxconf.src_addr            = p->port.mapbase + UART_RX;
 174
 175         dma->txconf.direction           = DMA_MEM_TO_DEV;
 176         dma->txconf.dst_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 177         dma->txconf.dst_addr            = p->port.mapbase + UART_TX;
 178
 179         dma_cap_zero(mask);
 180         dma_cap_set(DMA_SLAVE, mask);
 181
 182         /* Get a channel for RX */
 183         dma->rxchan = dma_request_slave_channel_compat(mask,
 184                                                        dma->fn, dma->rx_param,
 185                                                        p->port.dev, "rx");
 186         if (!dma->rxchan)
 187                 return -ENODEV;
 188
 189         dmaengine_slave_config(dma->rxchan, &dma->rxconf);
 190
 191         /* Get a channel for TX */
 192         dma->txchan = dma_request_slave_channel_compat(mask,
 193                                                        dma->fn, dma->tx_param,
 194                                                        p->port.dev, "tx");
 195         if (!dma->txchan) {
 196                 dma_release_channel(dma->rxchan);
 197                 return -ENODEV;
 198         }
 199
 200         dmaengine_slave_config(dma->txchan, &dma->txconf);
 201
 202         /* RX buffer */
 203         if (!dma->rx_size)
 204                 dma->rx_size = PAGE_SIZE;
 205
 206         dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
 207                                         &dma->rx_addr, GFP_KERNEL);
 208         if (!dma->rx_buf)
 209                 goto err;
 210
 211         /* TX buffer */
 212         dma->tx_addr = dma_map_single(dma->txchan->device->dev,
 213                                         p->port.state->xmit.buf,
 214                                         UART_XMIT_SIZE,
 215                                         DMA_TO_DEVICE);
 216         if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
 217                 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
 218                                   dma->rx_buf, dma->rx_addr);
 219                 goto err;
 220         }
 221
 222         dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
 223
 224         return 0;
 225 err:
 226         dma_release_channel(dma->rxchan);
 227         dma_release_channel(dma->txchan);
 228
 229         return -ENOMEM;
 230 }
 231 EXPORT_SYMBOL_GPL(serial8250_request_dma);
 232
 233 void serial8250_release_dma(struct uart_8250_port *p)
 234 {
 235         struct uart_8250_dma *dma = p->dma;
 236
 237         if (!dma)
 238                 return;
 239
 240         /* Release RX resources */
 241         dmaengine_terminate_all(dma->rxchan);
 242         dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 243                           dma->rx_addr);
 244         dma_release_channel(dma->rxchan);
 245         dma->rxchan = NULL;
 246
 247         /* Release TX resources */
 248         dmaengine_terminate_all(dma->txchan);
 249         dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 250                          UART_XMIT_SIZE, DMA_TO_DEVICE);
 251         dma_release_channel(dma->txchan);
 252         dma->txchan = NULL;
 253         dma->tx_running = 0;
 254
 255         dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
 256 }
 257 EXPORT_SYMBOL_GPL(serial8250_release_dma);