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         if (dma->tx_size < p->port.fifosize) {
  84                 ret = -EINVAL;
  85                 goto err;
  86         }
  87
  88         desc = dmaengine_prep_slave_single(dma->txchan,
  89                                            dma->tx_addr + xmit->tail,
  90                                            dma->tx_size, DMA_MEM_TO_DEV,
  91                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
  92         if (!desc) {
  93                 ret = -EBUSY;
  94                 goto err;
  95         }
  96
  97         dma->tx_running = 1;
  98         desc->callback = __dma_tx_complete;
  99         desc->callback_param = p;
 100
 101         dma->tx_cookie = dmaengine_submit(desc);
 102
 103         dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
 104                                    UART_XMIT_SIZE, DMA_TO_DEVICE);
 105
 106         dma_async_issue_pending(dma->txchan);
 107         if (dma->tx_err) {
 108                 dma->tx_err = 0;
 109                 if (p->ier & UART_IER_THRI) {
 110                         p->ier &= ~UART_IER_THRI;
 111                         serial_out(p, UART_IER, p->ier);
 112                 }
 113         }
 114         return 0;
 115 err:
 116         dma->tx_err = 1;
 117         return ret;
 118 }
 119
 120 int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
 121 {
 122         struct uart_8250_dma            *dma = p->dma;
 123         struct dma_async_tx_descriptor  *desc;
 124
 125         switch (iir & 0x3f) {
 126         case UART_IIR_RLSI:
 127                 /* 8250_core handles errors and break interrupts */
 128                 return -EIO;
 129         case UART_IIR_RX_TIMEOUT:
 130                 /*
 131                  * If RCVR FIFO trigger level was not reached, complete the
 132                  * transfer and let 8250_core copy the remaining data.
 133                  */
 134                 if (dma->rx_running) {
 135                         dmaengine_pause(dma->rxchan);
 136                         __dma_rx_complete(p);
 137                         dmaengine_terminate_all(dma->rxchan);
 138                 }
 139                 return -ETIMEDOUT;
 140         default:
 141                 break;
 142         }
 143
 144         if (dma->rx_running)
 145                 return 0;
 146
 147         desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
 148                                            dma->rx_size, DMA_DEV_TO_MEM,
 149                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 150         if (!desc)
 151                 return -EBUSY;
 152
 153         dma->rx_running = 1;
 154         desc->callback = __dma_rx_complete;
 155         desc->callback_param = p;
 156
 157         dma->rx_cookie = dmaengine_submit(desc);
 158
 159         dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr,
 160                                    dma->rx_size, DMA_FROM_DEVICE);
 161
 162         dma_async_issue_pending(dma->rxchan);
 163
 164         return 0;
 165 }
 166
 167 int serial8250_request_dma(struct uart_8250_port *p)
 168 {
 169         struct uart_8250_dma    *dma = p->dma;
 170         dma_cap_mask_t          mask;
 171
 172         /* Default slave configuration parameters */
 173         dma->rxconf.direction           = DMA_DEV_TO_MEM;
 174         dma->rxconf.src_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 175         dma->rxconf.src_addr            = p->port.mapbase + UART_RX;
 176
 177         dma->txconf.direction           = DMA_MEM_TO_DEV;
 178         dma->txconf.dst_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 179         dma->txconf.dst_addr            = p->port.mapbase + UART_TX;
 180
 181         dma_cap_zero(mask);
 182         dma_cap_set(DMA_SLAVE, mask);
 183
 184         /* Get a channel for RX */
 185         dma->rxchan = dma_request_slave_channel_compat(mask,
 186                                                        dma->fn, dma->rx_param,
 187                                                        p->port.dev, "rx");
 188         if (!dma->rxchan)
 189                 return -ENODEV;
 190
 191         dmaengine_slave_config(dma->rxchan, &dma->rxconf);
 192
 193         /* Get a channel for TX */
 194         dma->txchan = dma_request_slave_channel_compat(mask,
 195                                                        dma->fn, dma->tx_param,
 196                                                        p->port.dev, "tx");
 197         if (!dma->txchan) {
 198                 dma_release_channel(dma->rxchan);
 199                 return -ENODEV;
 200         }
 201
 202         dmaengine_slave_config(dma->txchan, &dma->txconf);
 203
 204         /* RX buffer */
 205         if (!dma->rx_size)
 206                 dma->rx_size = PAGE_SIZE;
 207
 208         dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
 209                                         &dma->rx_addr, GFP_KERNEL);
 210         if (!dma->rx_buf)
 211                 goto err;
 212
 213         /* TX buffer */
 214         dma->tx_addr = dma_map_single(dma->txchan->device->dev,
 215                                         p->port.state->xmit.buf,
 216                                         UART_XMIT_SIZE,
 217                                         DMA_TO_DEVICE);
 218         if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
 219                 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
 220                                   dma->rx_buf, dma->rx_addr);
 221                 goto err;
 222         }
 223
 224         dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
 225
 226         return 0;
 227 err:
 228         dma_release_channel(dma->rxchan);
 229         dma_release_channel(dma->txchan);
 230
 231         return -ENOMEM;
 232 }
 233 EXPORT_SYMBOL_GPL(serial8250_request_dma);
 234
 235 void serial8250_release_dma(struct uart_8250_port *p)
 236 {
 237         struct uart_8250_dma *dma = p->dma;
 238
 239         if (!dma)
 240                 return;
 241
 242         /* Release RX resources */
 243         dmaengine_terminate_all(dma->rxchan);
 244         dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 245                           dma->rx_addr);
 246         dma_release_channel(dma->rxchan);
 247         dma->rxchan = NULL;
 248
 249         /* Release TX resources */
 250         dmaengine_terminate_all(dma->txchan);
 251         dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 252                          UART_XMIT_SIZE, DMA_TO_DEVICE);
 253         dma_release_channel(dma->txchan);
 254         dma->txchan = NULL;
 255         dma->tx_running = 0;
 256
 257         dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
 258 }
 259 EXPORT_SYMBOL_GPL(serial8250_release_dma);