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

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * 8250_dma.c - DMA Engine API support for 8250.c
   4  *
   5  * Copyright (C) 2013 Intel Corporation
   6  */
   7 #include <linux/tty.h>
   8 #include <linux/tty_flip.h>
   9 #include <linux/serial_reg.h>
  10 #include <linux/dma-mapping.h>
  11
  12 #include "8250.h"
  13
  14 static void __dma_tx_complete(void *param)
  15 {
  16         struct uart_8250_port   *p = param;
  17         struct uart_8250_dma    *dma = p->dma;
  18         struct circ_buf         *xmit = &p->port.state->xmit;
  19         unsigned long   flags;
  20         int             ret;
  21
  22         dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr,
  23                                 UART_XMIT_SIZE, DMA_TO_DEVICE);
  24
  25         spin_lock_irqsave(&p->port.lock, flags);
  26
  27         dma->tx_running = 0;
  28
  29         xmit->tail += dma->tx_size;
  30         xmit->tail &= UART_XMIT_SIZE - 1;
  31         p->port.icount.tx += dma->tx_size;
  32
  33         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
  34                 uart_write_wakeup(&p->port);
  35
  36         ret = serial8250_tx_dma(p);
  37         if (ret)
  38                 serial8250_set_THRI(p);
  39
  40         spin_unlock_irqrestore(&p->port.lock, flags);
  41 }
  42
  43 static void __dma_rx_complete(void *param)
  44 {
  45         struct uart_8250_port   *p = param;
  46         struct uart_8250_dma    *dma = p->dma;
  47         struct tty_port         *tty_port = &p->port.state->port;
  48         struct dma_tx_state     state;
  49         int                     count;
  50
  51         dma->rx_running = 0;
  52         dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
  53
  54         count = dma->rx_size - state.residue;
  55
  56         tty_insert_flip_string(tty_port, dma->rx_buf, count);
  57         p->port.icount.rx += count;
  58
  59         tty_flip_buffer_push(tty_port);
  60 }
  61
  62 int serial8250_tx_dma(struct uart_8250_port *p)
  63 {
  64         struct uart_8250_dma            *dma = p->dma;
  65         struct circ_buf                 *xmit = &p->port.state->xmit;
  66         struct dma_async_tx_descriptor  *desc;
  67         int ret;
  68
  69         if (dma->tx_running)
  70                 return 0;
  71
  72         if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
  73                 /* We have been called from __dma_tx_complete() */
  74                 serial8250_rpm_put_tx(p);
  75                 return 0;
  76         }
  77
  78         dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
  79
  80         desc = dmaengine_prep_slave_single(dma->txchan,
  81                                            dma->tx_addr + xmit->tail,
  82                                            dma->tx_size, DMA_MEM_TO_DEV,
  83                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
  84         if (!desc) {
  85                 ret = -EBUSY;
  86                 goto err;
  87         }
  88
  89         dma->tx_running = 1;
  90         desc->callback = __dma_tx_complete;
  91         desc->callback_param = p;
  92
  93         dma->tx_cookie = dmaengine_submit(desc);
  94
  95         dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
  96                                    UART_XMIT_SIZE, DMA_TO_DEVICE);
  97
  98         dma_async_issue_pending(dma->txchan);
  99         if (dma->tx_err) {
 100                 dma->tx_err = 0;
 101                 serial8250_clear_THRI(p);
 102         }
 103         return 0;
 104 err:
 105         dma->tx_err = 1;
 106         return ret;
 107 }
 108
 109 int serial8250_rx_dma(struct uart_8250_port *p)
 110 {
 111         struct uart_8250_dma            *dma = p->dma;
 112         struct dma_async_tx_descriptor  *desc;
 113
 114         if (dma->rx_running)
 115                 return 0;
 116
 117         desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
 118                                            dma->rx_size, DMA_DEV_TO_MEM,
 119                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 120         if (!desc)
 121                 return -EBUSY;
 122
 123         dma->rx_running = 1;
 124         desc->callback = __dma_rx_complete;
 125         desc->callback_param = p;
 126
 127         dma->rx_cookie = dmaengine_submit(desc);
 128
 129         dma_async_issue_pending(dma->rxchan);
 130
 131         return 0;
 132 }
 133
 134 void serial8250_rx_dma_flush(struct uart_8250_port *p)
 135 {
 136         struct uart_8250_dma *dma = p->dma;
 137
 138         if (dma->rx_running) {
 139                 dmaengine_pause(dma->rxchan);
 140                 __dma_rx_complete(p);
 141                 dmaengine_terminate_async(dma->rxchan);
 142         }
 143 }
 144 EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
 145
 146 int serial8250_request_dma(struct uart_8250_port *p)
 147 {
 148         struct uart_8250_dma    *dma = p->dma;
 149         phys_addr_t rx_dma_addr = dma->rx_dma_addr ?
 150                                   dma->rx_dma_addr : p->port.mapbase;
 151         phys_addr_t tx_dma_addr = dma->tx_dma_addr ?
 152                                   dma->tx_dma_addr : p->port.mapbase;
 153         dma_cap_mask_t          mask;
 154         struct dma_slave_caps   caps;
 155         int                     ret;
 156
 157         /* Default slave configuration parameters */
 158         dma->rxconf.direction           = DMA_DEV_TO_MEM;
 159         dma->rxconf.src_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 160         dma->rxconf.src_addr            = rx_dma_addr + UART_RX;
 161
 162         dma->txconf.direction           = DMA_MEM_TO_DEV;
 163         dma->txconf.dst_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 164         dma->txconf.dst_addr            = tx_dma_addr + UART_TX;
 165
 166         dma_cap_zero(mask);
 167         dma_cap_set(DMA_SLAVE, mask);
 168
 169         /* Get a channel for RX */
 170         dma->rxchan = dma_request_slave_channel_compat(mask,
 171                                                        dma->fn, dma->rx_param,
 172                                                        p->port.dev, "rx");
 173         if (!dma->rxchan)
 174                 return -ENODEV;
 175
 176         /* 8250 rx dma requires dmaengine driver to support pause/terminate */
 177         ret = dma_get_slave_caps(dma->rxchan, &caps);
 178         if (ret)
 179                 goto release_rx;
 180         if (!caps.cmd_pause || !caps.cmd_terminate ||
 181             caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
 182                 ret = -EINVAL;
 183                 goto release_rx;
 184         }
 185
 186         dmaengine_slave_config(dma->rxchan, &dma->rxconf);
 187
 188         /* Get a channel for TX */
 189         dma->txchan = dma_request_slave_channel_compat(mask,
 190                                                        dma->fn, dma->tx_param,
 191                                                        p->port.dev, "tx");
 192         if (!dma->txchan) {
 193                 ret = -ENODEV;
 194                 goto release_rx;
 195         }
 196
 197         /* 8250 tx dma requires dmaengine driver to support terminate */
 198         ret = dma_get_slave_caps(dma->txchan, &caps);
 199         if (ret)
 200                 goto err;
 201         if (!caps.cmd_terminate) {
 202                 ret = -EINVAL;
 203                 goto err;
 204         }
 205
 206         dmaengine_slave_config(dma->txchan, &dma->txconf);
 207
 208         /* RX buffer */
 209         if (!dma->rx_size)
 210                 dma->rx_size = PAGE_SIZE;
 211
 212         dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
 213                                         &dma->rx_addr, GFP_KERNEL);
 214         if (!dma->rx_buf) {
 215                 ret = -ENOMEM;
 216                 goto err;
 217         }
 218
 219         /* TX buffer */
 220         dma->tx_addr = dma_map_single(dma->txchan->device->dev,
 221                                         p->port.state->xmit.buf,
 222                                         UART_XMIT_SIZE,
 223                                         DMA_TO_DEVICE);
 224         if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
 225                 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
 226                                   dma->rx_buf, dma->rx_addr);
 227                 ret = -ENOMEM;
 228                 goto err;
 229         }
 230
 231         dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
 232
 233         return 0;
 234 err:
 235         dma_release_channel(dma->txchan);
 236 release_rx:
 237         dma_release_channel(dma->rxchan);
 238         return ret;
 239 }
 240 EXPORT_SYMBOL_GPL(serial8250_request_dma);
 241
 242 void serial8250_release_dma(struct uart_8250_port *p)
 243 {
 244         struct uart_8250_dma *dma = p->dma;
 245
 246         if (!dma)
 247                 return;
 248
 249         /* Release RX resources */
 250         dmaengine_terminate_sync(dma->rxchan);
 251         dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 252                           dma->rx_addr);
 253         dma_release_channel(dma->rxchan);
 254         dma->rxchan = NULL;
 255
 256         /* Release TX resources */
 257         dmaengine_terminate_sync(dma->txchan);
 258         dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 259                          UART_XMIT_SIZE, DMA_TO_DEVICE);
 260         dma_release_channel(dma->txchan);
 261         dma->txchan = NULL;
 262         dma->tx_running = 0;
 263
 264         dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
 265 }
 266 EXPORT_SYMBOL_GPL(serial8250_release_dma);