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  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  */
  12 #include <linux/tty.h>
  13 #include <linux/tty_flip.h>
  14 #include <linux/serial_reg.h>
  15 #include <linux/dma-mapping.h>
  16
  17 #include "8250.h"
  18
  19 static void __dma_tx_complete(void *param)
  20 {
  21         struct uart_8250_port   *p = param;
  22         struct uart_8250_dma    *dma = p->dma;
  23         struct circ_buf         *xmit = &p->port.state->xmit;
  24         unsigned long   flags;
  25         int             ret;
  26
  27         dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr,
  28                                 UART_XMIT_SIZE, DMA_TO_DEVICE);
  29
  30         spin_lock_irqsave(&p->port.lock, flags);
  31
  32         dma->tx_running = 0;
  33
  34         xmit->tail += dma->tx_size;
  35         xmit->tail &= UART_XMIT_SIZE - 1;
  36         p->port.icount.tx += dma->tx_size;
  37
  38         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
  39                 uart_write_wakeup(&p->port);
  40
  41         ret = serial8250_tx_dma(p);
  42         if (ret) {
  43                 p->ier |= UART_IER_THRI;
  44                 serial_port_out(&p->port, UART_IER, p->ier);
  45         }
  46
  47         spin_unlock_irqrestore(&p->port.lock, flags);
  48 }
  49
  50 static void __dma_rx_complete(void *param)
  51 {
  52         struct uart_8250_port   *p = param;
  53         struct uart_8250_dma    *dma = p->dma;
  54         struct tty_port         *tty_port = &p->port.state->port;
  55         struct dma_tx_state     state;
  56         int                     count;
  57
  58         dma->rx_running = 0;
  59         dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
  60
  61         count = dma->rx_size - state.residue;
  62
  63         tty_insert_flip_string(tty_port, dma->rx_buf, count);
  64         p->port.icount.rx += count;
  65
  66         tty_flip_buffer_push(tty_port);
  67 }
  68
  69 int serial8250_tx_dma(struct uart_8250_port *p)
  70 {
  71         struct uart_8250_dma            *dma = p->dma;
  72         struct circ_buf                 *xmit = &p->port.state->xmit;
  73         struct dma_async_tx_descriptor  *desc;
  74         int ret;
  75
  76         if (dma->tx_running)
  77                 return 0;
  78
  79         if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
  80                 /* We have been called from __dma_tx_complete() */
  81                 serial8250_rpm_put_tx(p);
  82                 return 0;
  83         }
  84
  85         dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
  86
  87         desc = dmaengine_prep_slave_single(dma->txchan,
  88                                            dma->tx_addr + xmit->tail,
  89                                            dma->tx_size, DMA_MEM_TO_DEV,
  90                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
  91         if (!desc) {
  92                 ret = -EBUSY;
  93                 goto err;
  94         }
  95
  96         dma->tx_running = 1;
  97         desc->callback = __dma_tx_complete;
  98         desc->callback_param = p;
  99
 100         dma->tx_cookie = dmaengine_submit(desc);
 101
 102         dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
 103                                    UART_XMIT_SIZE, DMA_TO_DEVICE);
 104
 105         dma_async_issue_pending(dma->txchan);
 106         if (dma->tx_err) {
 107                 dma->tx_err = 0;
 108                 if (p->ier & UART_IER_THRI) {
 109                         p->ier &= ~UART_IER_THRI;
 110                         serial_out(p, UART_IER, p->ier);
 111                 }
 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         desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
 128                                            dma->rx_size, DMA_DEV_TO_MEM,
 129                                            DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 130         if (!desc)
 131                 return -EBUSY;
 132
 133         dma->rx_running = 1;
 134         desc->callback = __dma_rx_complete;
 135         desc->callback_param = p;
 136
 137         dma->rx_cookie = dmaengine_submit(desc);
 138
 139         dma_async_issue_pending(dma->rxchan);
 140
 141         return 0;
 142 }
 143
 144 void serial8250_rx_dma_flush(struct uart_8250_port *p)
 145 {
 146         struct uart_8250_dma *dma = p->dma;
 147
 148         if (dma->rx_running) {
 149                 dmaengine_pause(dma->rxchan);
 150                 __dma_rx_complete(p);
 151                 dmaengine_terminate_async(dma->rxchan);
 152         }
 153 }
 154 EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
 155
 156 int serial8250_request_dma(struct uart_8250_port *p)
 157 {
 158         struct uart_8250_dma    *dma = p->dma;
 159         phys_addr_t rx_dma_addr = dma->rx_dma_addr ?
 160                                   dma->rx_dma_addr : p->port.mapbase;
 161         phys_addr_t tx_dma_addr = dma->tx_dma_addr ?
 162                                   dma->tx_dma_addr : p->port.mapbase;
 163         dma_cap_mask_t          mask;
 164         struct dma_slave_caps   caps;
 165         int                     ret;
 166
 167         /* Default slave configuration parameters */
 168         dma->rxconf.direction           = DMA_DEV_TO_MEM;
 169         dma->rxconf.src_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 170         dma->rxconf.src_addr            = rx_dma_addr + UART_RX;
 171
 172         dma->txconf.direction           = DMA_MEM_TO_DEV;
 173         dma->txconf.dst_addr_width      = DMA_SLAVE_BUSWIDTH_1_BYTE;
 174         dma->txconf.dst_addr            = tx_dma_addr + UART_TX;
 175
 176         dma_cap_zero(mask);
 177         dma_cap_set(DMA_SLAVE, mask);
 178
 179         /* Get a channel for RX */
 180         dma->rxchan = dma_request_slave_channel_compat(mask,
 181                                                        dma->fn, dma->rx_param,
 182                                                        p->port.dev, "rx");
 183         if (!dma->rxchan)
 184                 return -ENODEV;
 185
 186         /* 8250 rx dma requires dmaengine driver to support pause/terminate */
 187         ret = dma_get_slave_caps(dma->rxchan, &caps);
 188         if (ret)
 189                 goto release_rx;
 190         if (!caps.cmd_pause || !caps.cmd_terminate ||
 191             caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
 192                 ret = -EINVAL;
 193                 goto release_rx;
 194         }
 195
 196         dmaengine_slave_config(dma->rxchan, &dma->rxconf);
 197
 198         /* Get a channel for TX */
 199         dma->txchan = dma_request_slave_channel_compat(mask,
 200                                                        dma->fn, dma->tx_param,
 201                                                        p->port.dev, "tx");
 202         if (!dma->txchan) {
 203                 ret = -ENODEV;
 204                 goto release_rx;
 205         }
 206
 207         /* 8250 tx dma requires dmaengine driver to support terminate */
 208         ret = dma_get_slave_caps(dma->txchan, &caps);
 209         if (ret)
 210                 goto err;
 211         if (!caps.cmd_terminate) {
 212                 ret = -EINVAL;
 213                 goto err;
 214         }
 215
 216         dmaengine_slave_config(dma->txchan, &dma->txconf);
 217
 218         /* RX buffer */
 219         if (!dma->rx_size)
 220                 dma->rx_size = PAGE_SIZE;
 221
 222         dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
 223                                         &dma->rx_addr, GFP_KERNEL);
 224         if (!dma->rx_buf) {
 225                 ret = -ENOMEM;
 226                 goto err;
 227         }
 228
 229         /* TX buffer */
 230         dma->tx_addr = dma_map_single(dma->txchan->device->dev,
 231                                         p->port.state->xmit.buf,
 232                                         UART_XMIT_SIZE,
 233                                         DMA_TO_DEVICE);
 234         if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
 235                 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
 236                                   dma->rx_buf, dma->rx_addr);
 237                 ret = -ENOMEM;
 238                 goto err;
 239         }
 240
 241         dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
 242
 243         return 0;
 244 err:
 245         dma_release_channel(dma->txchan);
 246 release_rx:
 247         dma_release_channel(dma->rxchan);
 248         return ret;
 249 }
 250 EXPORT_SYMBOL_GPL(serial8250_request_dma);
 251
 252 void serial8250_release_dma(struct uart_8250_port *p)
 253 {
 254         struct uart_8250_dma *dma = p->dma;
 255
 256         if (!dma)
 257                 return;
 258
 259         /* Release RX resources */
 260         dmaengine_terminate_sync(dma->rxchan);
 261         dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 262                           dma->rx_addr);
 263         dma_release_channel(dma->rxchan);
 264         dma->rxchan = NULL;
 265
 266         /* Release TX resources */
 267         dmaengine_terminate_sync(dma->txchan);
 268         dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 269                          UART_XMIT_SIZE, DMA_TO_DEVICE);
 270         dma_release_channel(dma->txchan);
 271         dma->txchan = NULL;
 272         dma->tx_running = 0;
 273
 274         dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
 275 }
 276 EXPORT_SYMBOL_GPL(serial8250_release_dma);