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         int                     count;
  52
  53         dma->rx_running = 0;
  54         dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
  55
  56         count = dma->rx_size - state.residue;
  57
  58         tty_insert_flip_string(tty_port, dma->rx_buf, count);
  59         p->port.icount.rx += count;
  60
  61         tty_flip_buffer_push(tty_port);
  62 }
  63
  64 int serial8250_tx_dma(struct uart_8250_port *p)
  65 {
  66         struct uart_8250_dma            *dma = p->dma;
  67         struct circ_buf                 *xmit = &p->port.state->xmit;
  68         struct dma_async_tx_descriptor  *desc;
  69         int ret;
  70
  71         if (dma->tx_running)
  72                 return 0;
  73
  74         if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
  75                 /* We have been called from __dma_tx_complete() */
  76                 serial8250_rpm_put_tx(p);
  77                 return 0;
  78         }
  79
  80         dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
  81
  82         desc = dmaengine_prep_slave_single(dma->txchan,
  83                                            dma->tx_addr + xmit->tail,
  84                                            dma->tx_size, DMA_MEM_TO_DEV,
  85                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
  86         if (!desc) {
  87                 ret = -EBUSY;
  88                 goto err;
  89         }
  90
  91         dma->tx_running = 1;
  92         desc->callback = __dma_tx_complete;
  93         desc->callback_param = p;
  94
  95         dma->tx_cookie = dmaengine_submit(desc);
  96
  97         dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
  98                                    UART_XMIT_SIZE, DMA_TO_DEVICE);
  99
 100         dma_async_issue_pending(dma->txchan);
 101         if (dma->tx_err) {
 102                 dma->tx_err = 0;
 103                 if (p->ier & UART_IER_THRI) {
 104                         p->ier &= ~UART_IER_THRI;
 105                         serial_out(p, UART_IER, p->ier);
 106                 }
 107         }
 108         return 0;
 109 err:
 110         dma->tx_err = 1;
 111         return ret;
 112 }
 113
 114 int serial8250_rx_dma(struct uart_8250_port *p)
 115 {
 116         struct uart_8250_dma            *dma = p->dma;
 117         struct dma_async_tx_descriptor  *desc;
 118
 119         if (dma->rx_running)
 120                 return 0;
 121
 122         desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
 123                                            dma->rx_size, DMA_DEV_TO_MEM,
 124                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 125         if (!desc)
 126                 return -EBUSY;
 127
 128         dma->rx_running = 1;
 129         desc->callback = __dma_rx_complete;
 130         desc->callback_param = p;
 131
 132         dma->rx_cookie = dmaengine_submit(desc);
 133
 134         dma_async_issue_pending(dma->rxchan);
 135
 136         return 0;
 137 }
 138
 139 void serial8250_rx_dma_flush(struct uart_8250_port *p)
 140 {
 141         struct uart_8250_dma *dma = p->dma;
 142
 143         if (dma->rx_running) {
 144                 dmaengine_pause(dma->rxchan);
 145                 __dma_rx_complete(p);
 146                 dmaengine_terminate_async(dma->rxchan);
 147         }
 148 }
 149 EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
 150
 151 int serial8250_request_dma(struct uart_8250_port *p)
 152 {
 153         struct uart_8250_dma    *dma = p->dma;
 154         phys_addr_t rx_dma_addr = dma->rx_dma_addr ?
 155                                   dma->rx_dma_addr : p->port.mapbase;
 156         phys_addr_t tx_dma_addr = dma->tx_dma_addr ?
 157                                   dma->tx_dma_addr : p->port.mapbase;
 158         dma_cap_mask_t          mask;
 159         struct dma_slave_caps   caps;
 160         int                     ret;
 161
 162         /* Default slave configuration parameters */
 163         dma->rxconf.direction           = DMA_DEV_TO_MEM;
 164         dma->rxconf.src_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 165         dma->rxconf.src_addr            = rx_dma_addr + UART_RX;
 166
 167         dma->txconf.direction           = DMA_MEM_TO_DEV;
 168         dma->txconf.dst_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 169         dma->txconf.dst_addr            = tx_dma_addr + UART_TX;
 170
 171         dma_cap_zero(mask);
 172         dma_cap_set(DMA_SLAVE, mask);
 173
 174         /* Get a channel for RX */
 175         dma->rxchan = dma_request_slave_channel_compat(mask,
 176                                                        dma->fn, dma->rx_param,
 177                                                        p->port.dev, "rx");
 178         if (!dma->rxchan)
 179                 return -ENODEV;
 180
 181         /* 8250 rx dma requires dmaengine driver to support pause/terminate */
 182         ret = dma_get_slave_caps(dma->rxchan, &caps);
 183         if (ret)
 184                 goto release_rx;
 185         if (!caps.cmd_pause || !caps.cmd_terminate ||
 186             caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
 187                 ret = -EINVAL;
 188                 goto release_rx;
 189         }
 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                 ret = -ENODEV;
 199                 goto release_rx;
 200         }
 201
 202         /* 8250 tx dma requires dmaengine driver to support terminate */
 203         ret = dma_get_slave_caps(dma->txchan, &caps);
 204         if (ret)
 205                 goto err;
 206         if (!caps.cmd_terminate) {
 207                 ret = -EINVAL;
 208                 goto err;
 209         }
 210
 211         dmaengine_slave_config(dma->txchan, &dma->txconf);
 212
 213         /* RX buffer */
 214         if (!dma->rx_size)
 215                 dma->rx_size = PAGE_SIZE;
 216
 217         dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
 218                                         &dma->rx_addr, GFP_KERNEL);
 219         if (!dma->rx_buf) {
 220                 ret = -ENOMEM;
 221                 goto err;
 222         }
 223
 224         /* TX buffer */
 225         dma->tx_addr = dma_map_single(dma->txchan->device->dev,
 226                                         p->port.state->xmit.buf,
 227                                         UART_XMIT_SIZE,
 228                                         DMA_TO_DEVICE);
 229         if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
 230                 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
 231                                   dma->rx_buf, dma->rx_addr);
 232                 ret = -ENOMEM;
 233                 goto err;
 234         }
 235
 236         dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
 237
 238         return 0;
 239 err:
 240         dma_release_channel(dma->txchan);
 241 release_rx:
 242         dma_release_channel(dma->rxchan);
 243         return ret;
 244 }
 245 EXPORT_SYMBOL_GPL(serial8250_request_dma);
 246
 247 void serial8250_release_dma(struct uart_8250_port *p)
 248 {
 249         struct uart_8250_dma *dma = p->dma;
 250
 251         if (!dma)
 252                 return;
 253
 254         /* Release RX resources */
 255         dmaengine_terminate_sync(dma->rxchan);
 256         dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 257                           dma->rx_addr);
 258         dma_release_channel(dma->rxchan);
 259         dma->rxchan = NULL;
 260
 261         /* Release TX resources */
 262         dmaengine_terminate_sync(dma->txchan);
 263         dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 264                          UART_XMIT_SIZE, DMA_TO_DEVICE);
 265         dma_release_channel(dma->txchan);
 266         dma->txchan = NULL;
 267         dma->tx_running = 0;
 268
 269         dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
 270 }
 271 EXPORT_SYMBOL_GPL(serial8250_release_dma);