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 || !dma->tx_running)
  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         struct uart_port                *up = &p->port;
  68         int ret;
  69
  70         if (dma->tx_running) {
  71                 if (up->x_char) {
  72                         dmaengine_pause(dma->txchan);
  73                         uart_xchar_out(up, UART_TX);
  74                         dmaengine_resume(dma->txchan);
  75                 }
  76                 return 0;
  77         } else if (up->x_char) {
  78                 uart_xchar_out(up, UART_TX);
  79         }
  80
  81         if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
  82                 /* We have been called from __dma_tx_complete() */
  83                 return 0;
  84         }
  85
  86         dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
  87
  88         serial8250_do_prepare_tx_dma(p);
  89
  90         desc = dmaengine_prep_slave_single(dma->txchan,
  91                                            dma->tx_addr + xmit->tail,
  92                                            dma->tx_size, DMA_MEM_TO_DEV,
  93                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
  94         if (!desc) {
  95                 ret = -EBUSY;
  96                 goto err;
  97         }
  98
  99         dma->tx_running = 1;
 100         desc->callback = __dma_tx_complete;
 101         desc->callback_param = p;
 102
 103         dma->tx_cookie = dmaengine_submit(desc);
 104
 105         dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
 106                                    UART_XMIT_SIZE, DMA_TO_DEVICE);
 107
 108         dma_async_issue_pending(dma->txchan);
 109         serial8250_clear_THRI(p);
 110         if (dma->tx_err)
 111                 dma->tx_err = 0;
 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)
 120 {
 121         struct uart_8250_dma            *dma = p->dma;
 122         struct dma_async_tx_descriptor  *desc;
 123
 124         if (dma->rx_running)
 125                 return 0;
 126
 127         serial8250_do_prepare_rx_dma(p);
 128
 129         desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
 130                                            dma->rx_size, DMA_DEV_TO_MEM,
 131                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 132         if (!desc)
 133                 return -EBUSY;
 134
 135         dma->rx_running = 1;
 136         desc->callback = __dma_rx_complete;
 137         desc->callback_param = p;
 138
 139         dma->rx_cookie = dmaengine_submit(desc);
 140
 141         dma_async_issue_pending(dma->rxchan);
 142
 143         return 0;
 144 }
 145
 146 void serial8250_rx_dma_flush(struct uart_8250_port *p)
 147 {
 148         struct uart_8250_dma *dma = p->dma;
 149
 150         if (dma->rx_running) {
 151                 dmaengine_pause(dma->rxchan);
 152                 __dma_rx_complete(p);
 153                 dmaengine_terminate_async(dma->rxchan);
 154         }
 155 }
 156 EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
 157
 158 int serial8250_request_dma(struct uart_8250_port *p)
 159 {
 160         struct uart_8250_dma    *dma = p->dma;
 161         phys_addr_t rx_dma_addr = dma->rx_dma_addr ?
 162                                   dma->rx_dma_addr : p->port.mapbase;
 163         phys_addr_t tx_dma_addr = dma->tx_dma_addr ?
 164                                   dma->tx_dma_addr : p->port.mapbase;
 165         dma_cap_mask_t          mask;
 166         struct dma_slave_caps   caps;
 167         int                     ret;
 168
 169         /* Default slave configuration parameters */
 170         dma->rxconf.direction           = DMA_DEV_TO_MEM;
 171         dma->rxconf.src_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 172         dma->rxconf.src_addr            = rx_dma_addr + UART_RX;
 173
 174         dma->txconf.direction           = DMA_MEM_TO_DEV;
 175         dma->txconf.dst_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 176         dma->txconf.dst_addr            = tx_dma_addr + UART_TX;
 177
 178         dma_cap_zero(mask);
 179         dma_cap_set(DMA_SLAVE, mask);
 180
 181         /* Get a channel for RX */
 182         dma->rxchan = dma_request_slave_channel_compat(mask,
 183                                                        dma->fn, dma->rx_param,
 184                                                        p->port.dev, "rx");
 185         if (!dma->rxchan)
 186                 return -ENODEV;
 187
 188         /* 8250 rx dma requires dmaengine driver to support pause/terminate */
 189         ret = dma_get_slave_caps(dma->rxchan, &caps);
 190         if (ret)
 191                 goto release_rx;
 192         if (!caps.cmd_pause || !caps.cmd_terminate ||
 193             caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
 194                 ret = -EINVAL;
 195                 goto release_rx;
 196         }
 197
 198         dmaengine_slave_config(dma->rxchan, &dma->rxconf);
 199
 200         /* Get a channel for TX */
 201         dma->txchan = dma_request_slave_channel_compat(mask,
 202                                                        dma->fn, dma->tx_param,
 203                                                        p->port.dev, "tx");
 204         if (!dma->txchan) {
 205                 ret = -ENODEV;
 206                 goto release_rx;
 207         }
 208
 209         /* 8250 tx dma requires dmaengine driver to support terminate */
 210         ret = dma_get_slave_caps(dma->txchan, &caps);
 211         if (ret)
 212                 goto err;
 213         if (!caps.cmd_terminate) {
 214                 ret = -EINVAL;
 215                 goto err;
 216         }
 217
 218         dmaengine_slave_config(dma->txchan, &dma->txconf);
 219
 220         /* RX buffer */
 221         if (!dma->rx_size)
 222                 dma->rx_size = PAGE_SIZE;
 223
 224         dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
 225                                         &dma->rx_addr, GFP_KERNEL);
 226         if (!dma->rx_buf) {
 227                 ret = -ENOMEM;
 228                 goto err;
 229         }
 230
 231         /* TX buffer */
 232         dma->tx_addr = dma_map_single(dma->txchan->device->dev,
 233                                         p->port.state->xmit.buf,
 234                                         UART_XMIT_SIZE,
 235                                         DMA_TO_DEVICE);
 236         if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
 237                 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
 238                                   dma->rx_buf, dma->rx_addr);
 239                 ret = -ENOMEM;
 240                 goto err;
 241         }
 242
 243         dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
 244
 245         return 0;
 246 err:
 247         dma_release_channel(dma->txchan);
 248 release_rx:
 249         dma_release_channel(dma->rxchan);
 250         return ret;
 251 }
 252 EXPORT_SYMBOL_GPL(serial8250_request_dma);
 253
 254 void serial8250_release_dma(struct uart_8250_port *p)
 255 {
 256         struct uart_8250_dma *dma = p->dma;
 257
 258         if (!dma)
 259                 return;
 260
 261         /* Release RX resources */
 262         dmaengine_terminate_sync(dma->rxchan);
 263         dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 264                           dma->rx_addr);
 265         dma_release_channel(dma->rxchan);
 266         dma->rxchan = NULL;
 267
 268         /* Release TX resources */
 269         dmaengine_terminate_sync(dma->txchan);
 270         dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 271                          UART_XMIT_SIZE, DMA_TO_DEVICE);
 272         dma_release_channel(dma->txchan);
 273         dma->txchan = NULL;
 274         dma->tx_running = 0;
 275
 276         dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
 277 }
 278 EXPORT_SYMBOL_GPL(serial8250_release_dma);