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                 p->ier |= UART_IER_THRI;
  39                 serial_port_out(&p->port, UART_IER, p->ier);
  40         }
  41
  42         spin_unlock_irqrestore(&p->port.lock, flags);
  43 }
  44
  45 static void __dma_rx_complete(void *param)
  46 {
  47         struct uart_8250_port   *p = param;
  48         struct uart_8250_dma    *dma = p->dma;
  49         struct tty_port         *tty_port = &p->port.state->port;
  50         struct dma_tx_state     state;
  51         enum dma_status         dma_status;
  52         int                     count;
  53
  54         /*
  55          * New DMA Rx can be started during the completion handler before it
  56          * could acquire port's lock and it might still be ongoing. Don't to
  57          * anything in such case.
  58          */
  59         dma_status = dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
  60         if (dma_status == DMA_IN_PROGRESS)
  61                 return;
  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         dma->rx_running = 0;
  68
  69         tty_flip_buffer_push(tty_port);
  70 }
  71
  72 static void dma_rx_complete(void *param)
  73 {
  74         struct uart_8250_port *p = param;
  75         struct uart_8250_dma *dma = p->dma;
  76         unsigned long flags;
  77
  78         spin_lock_irqsave(&p->port.lock, flags);
  79         if (dma->rx_running)
  80                 __dma_rx_complete(p);
  81         spin_unlock_irqrestore(&p->port.lock, flags);
  82 }
  83
  84 int serial8250_tx_dma(struct uart_8250_port *p)
  85 {
  86         struct uart_8250_dma            *dma = p->dma;
  87         struct circ_buf                 *xmit = &p->port.state->xmit;
  88         struct dma_async_tx_descriptor  *desc;
  89         int ret;
  90
  91         if (dma->tx_running)
  92                 return 0;
  93
  94         if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
  95                 /* We have been called from __dma_tx_complete() */
  96                 serial8250_rpm_put_tx(p);
  97                 return 0;
  98         }
  99
 100         dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
 101
 102         desc = dmaengine_prep_slave_single(dma->txchan,
 103                                            dma->tx_addr + xmit->tail,
 104                                            dma->tx_size, DMA_MEM_TO_DEV,
 105                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 106         if (!desc) {
 107                 ret = -EBUSY;
 108                 goto err;
 109         }
 110
 111         dma->tx_running = 1;
 112         desc->callback = __dma_tx_complete;
 113         desc->callback_param = p;
 114
 115         dma->tx_cookie = dmaengine_submit(desc);
 116
 117         dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
 118                                    UART_XMIT_SIZE, DMA_TO_DEVICE);
 119
 120         dma_async_issue_pending(dma->txchan);
 121         if (dma->tx_err) {
 122                 dma->tx_err = 0;
 123                 if (p->ier & UART_IER_THRI) {
 124                         p->ier &= ~UART_IER_THRI;
 125                         serial_out(p, UART_IER, p->ier);
 126                 }
 127         }
 128         return 0;
 129 err:
 130         dma->tx_err = 1;
 131         return ret;
 132 }
 133
 134 int serial8250_rx_dma(struct uart_8250_port *p)
 135 {
 136         struct uart_8250_dma            *dma = p->dma;
 137         struct dma_async_tx_descriptor  *desc;
 138
 139         if (dma->rx_running)
 140                 return 0;
 141
 142         desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
 143                                            dma->rx_size, DMA_DEV_TO_MEM,
 144                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 145         if (!desc)
 146                 return -EBUSY;
 147
 148         dma->rx_running = 1;
 149         desc->callback = dma_rx_complete;
 150         desc->callback_param = p;
 151
 152         dma->rx_cookie = dmaengine_submit(desc);
 153
 154         dma_async_issue_pending(dma->rxchan);
 155
 156         return 0;
 157 }
 158
 159 void serial8250_rx_dma_flush(struct uart_8250_port *p)
 160 {
 161         struct uart_8250_dma *dma = p->dma;
 162
 163         if (dma->rx_running) {
 164                 dmaengine_pause(dma->rxchan);
 165                 __dma_rx_complete(p);
 166                 dmaengine_terminate_async(dma->rxchan);
 167         }
 168 }
 169 EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
 170
 171 int serial8250_request_dma(struct uart_8250_port *p)
 172 {
 173         struct uart_8250_dma    *dma = p->dma;
 174         phys_addr_t rx_dma_addr = dma->rx_dma_addr ?
 175                                   dma->rx_dma_addr : p->port.mapbase;
 176         phys_addr_t tx_dma_addr = dma->tx_dma_addr ?
 177                                   dma->tx_dma_addr : p->port.mapbase;
 178         dma_cap_mask_t          mask;
 179         struct dma_slave_caps   caps;
 180         int                     ret;
 181
 182         /* Default slave configuration parameters */
 183         dma->rxconf.direction           = DMA_DEV_TO_MEM;
 184         dma->rxconf.src_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 185         dma->rxconf.src_addr            = rx_dma_addr + UART_RX;
 186
 187         dma->txconf.direction           = DMA_MEM_TO_DEV;
 188         dma->txconf.dst_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 189         dma->txconf.dst_addr            = tx_dma_addr + UART_TX;
 190
 191         dma_cap_zero(mask);
 192         dma_cap_set(DMA_SLAVE, mask);
 193
 194         /* Get a channel for RX */
 195         dma->rxchan = dma_request_slave_channel_compat(mask,
 196                                                        dma->fn, dma->rx_param,
 197                                                        p->port.dev, "rx");
 198         if (!dma->rxchan)
 199                 return -ENODEV;
 200
 201         /* 8250 rx dma requires dmaengine driver to support pause/terminate */
 202         ret = dma_get_slave_caps(dma->rxchan, &caps);
 203         if (ret)
 204                 goto release_rx;
 205         if (!caps.cmd_pause || !caps.cmd_terminate ||
 206             caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
 207                 ret = -EINVAL;
 208                 goto release_rx;
 209         }
 210
 211         dmaengine_slave_config(dma->rxchan, &dma->rxconf);
 212
 213         /* Get a channel for TX */
 214         dma->txchan = dma_request_slave_channel_compat(mask,
 215                                                        dma->fn, dma->tx_param,
 216                                                        p->port.dev, "tx");
 217         if (!dma->txchan) {
 218                 ret = -ENODEV;
 219                 goto release_rx;
 220         }
 221
 222         /* 8250 tx dma requires dmaengine driver to support terminate */
 223         ret = dma_get_slave_caps(dma->txchan, &caps);
 224         if (ret)
 225                 goto err;
 226         if (!caps.cmd_terminate) {
 227                 ret = -EINVAL;
 228                 goto err;
 229         }
 230
 231         dmaengine_slave_config(dma->txchan, &dma->txconf);
 232
 233         /* RX buffer */
 234         if (!dma->rx_size)
 235                 dma->rx_size = PAGE_SIZE;
 236
 237         dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
 238                                         &dma->rx_addr, GFP_KERNEL);
 239         if (!dma->rx_buf) {
 240                 ret = -ENOMEM;
 241                 goto err;
 242         }
 243
 244         /* TX buffer */
 245         dma->tx_addr = dma_map_single(dma->txchan->device->dev,
 246                                         p->port.state->xmit.buf,
 247                                         UART_XMIT_SIZE,
 248                                         DMA_TO_DEVICE);
 249         if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
 250                 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
 251                                   dma->rx_buf, dma->rx_addr);
 252                 ret = -ENOMEM;
 253                 goto err;
 254         }
 255
 256         dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
 257
 258         return 0;
 259 err:
 260         dma_release_channel(dma->txchan);
 261 release_rx:
 262         dma_release_channel(dma->rxchan);
 263         return ret;
 264 }
 265 EXPORT_SYMBOL_GPL(serial8250_request_dma);
 266
 267 void serial8250_release_dma(struct uart_8250_port *p)
 268 {
 269         struct uart_8250_dma *dma = p->dma;
 270
 271         if (!dma)
 272                 return;
 273
 274         /* Release RX resources */
 275         dmaengine_terminate_sync(dma->rxchan);
 276         dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 277                           dma->rx_addr);
 278         dma_release_channel(dma->rxchan);
 279         dma->rxchan = NULL;
 280
 281         /* Release TX resources */
 282         dmaengine_terminate_sync(dma->txchan);
 283         dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 284                          UART_XMIT_SIZE, DMA_TO_DEVICE);
 285         dma_release_channel(dma->txchan);
 286         dma->txchan = NULL;
 287         dma->tx_running = 0;
 288
 289         dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
 290 }
 291 EXPORT_SYMBOL_GPL(serial8250_release_dma);