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