drivers/spi/spi-pxa2xx-dma.c

   1 /*
   2  * PXA2xx SPI DMA engine support.
   3  *
   4  * Copyright (C) 2013, Intel Corporation
   5  * Author: Mika Westerberg <[email protected]>
   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 version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/device.h>
  13 #include <linux/dma-mapping.h>
  14 #include <linux/dmaengine.h>
  15 #include <linux/pxa2xx_ssp.h>
  16 #include <linux/scatterlist.h>
  17 #include <linux/sizes.h>
  18 #include <linux/spi/spi.h>
  19 #include <linux/spi/pxa2xx_spi.h>
  20
  21 #include "spi-pxa2xx.h"
  22
  23 static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
  24                                      enum dma_data_direction dir)
  25 {
  26         int i, nents, len = drv_data->len;
  27         struct scatterlist *sg;
  28         struct device *dmadev;
  29         struct sg_table *sgt;
  30         void *buf, *pbuf;
  31
  32         if (dir == DMA_TO_DEVICE) {
  33                 dmadev = drv_data->tx_chan->device->dev;
  34                 sgt = &drv_data->tx_sgt;
  35                 buf = drv_data->tx;
  36                 drv_data->tx_map_len = len;
  37         } else {
  38                 dmadev = drv_data->rx_chan->device->dev;
  39                 sgt = &drv_data->rx_sgt;
  40                 buf = drv_data->rx;
  41                 drv_data->rx_map_len = len;
  42         }
  43
  44         nents = DIV_ROUND_UP(len, SZ_2K);
  45         if (nents != sgt->nents) {
  46                 int ret;
  47
  48                 sg_free_table(sgt);
  49                 ret = sg_alloc_table(sgt, nents, GFP_ATOMIC);
  50                 if (ret)
  51                         return ret;
  52         }
  53
  54         pbuf = buf;
  55         for_each_sg(sgt->sgl, sg, sgt->nents, i) {
  56                 size_t bytes = min_t(size_t, len, SZ_2K);
  57
  58                 if (buf)
  59                         sg_set_buf(sg, pbuf, bytes);
  60                 else
  61                         sg_set_buf(sg, drv_data->dummy, bytes);
  62
  63                 pbuf += bytes;
  64                 len -= bytes;
  65         }
  66
  67         nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir);
  68         if (!nents)
  69                 return -ENOMEM;
  70
  71         return nents;
  72 }
  73
  74 static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data,
  75                                         enum dma_data_direction dir)
  76 {
  77         struct device *dmadev;
  78         struct sg_table *sgt;
  79
  80         if (dir == DMA_TO_DEVICE) {
  81                 dmadev = drv_data->tx_chan->device->dev;
  82                 sgt = &drv_data->tx_sgt;
  83         } else {
  84                 dmadev = drv_data->rx_chan->device->dev;
  85                 sgt = &drv_data->rx_sgt;
  86         }
  87
  88         dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir);
  89 }
  90
  91 static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data)
  92 {
  93         if (!drv_data->dma_mapped)
  94                 return;
  95
  96         pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE);
  97         pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
  98
  99         drv_data->dma_mapped = 0;
 100 }
 101
 102 static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
 103                                              bool error)
 104 {
 105         struct spi_message *msg = drv_data->cur_msg;
 106
 107         /*
 108          * It is possible that one CPU is handling ROR interrupt and other
 109          * just gets DMA completion. Calling pump_transfers() twice for the
 110          * same transfer leads to problems thus we prevent concurrent calls
 111          * by using ->dma_running.
 112          */
 113         if (atomic_dec_and_test(&drv_data->dma_running)) {
 114                 void __iomem *reg = drv_data->ioaddr;
 115
 116                 /*
 117                  * If the other CPU is still handling the ROR interrupt we
 118                  * might not know about the error yet. So we re-check the
 119                  * ROR bit here before we clear the status register.
 120                  */
 121                 if (!error) {
 122                         u32 status = read_SSSR(reg) & drv_data->mask_sr;
 123                         error = status & SSSR_ROR;
 124                 }
 125
 126                 /* Clear status & disable interrupts */
 127                 write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg);
 128                 write_SSSR_CS(drv_data, drv_data->clear_sr);
 129                 if (!pxa25x_ssp_comp(drv_data))
 130                         write_SSTO(0, reg);
 131
 132                 if (!error) {
 133                         pxa2xx_spi_unmap_dma_buffers(drv_data);
 134
 135                         drv_data->tx += drv_data->tx_map_len;
 136                         drv_data->rx += drv_data->rx_map_len;
 137
 138                         msg->actual_length += drv_data->len;
 139                         msg->state = pxa2xx_spi_next_transfer(drv_data);
 140                 } else {
 141                         /* In case we got an error we disable the SSP now */
 142                         write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);
 143
 144                         msg->state = ERROR_STATE;
 145                 }
 146
 147                 tasklet_schedule(&drv_data->pump_transfers);
 148         }
 149 }
 150
 151 static void pxa2xx_spi_dma_callback(void *data)
 152 {
 153         pxa2xx_spi_dma_transfer_complete(data, false);
 154 }
 155
 156 static struct dma_async_tx_descriptor *
 157 pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
 158                            enum dma_transfer_direction dir)
 159 {
 160         struct pxa2xx_spi_master *pdata = drv_data->master_info;
 161         struct chip_data *chip = drv_data->cur_chip;
 162         enum dma_slave_buswidth width;
 163         struct dma_slave_config cfg;
 164         struct dma_chan *chan;
 165         struct sg_table *sgt;
 166         int nents, ret;
 167
 168         switch (drv_data->n_bytes) {
 169         case 1:
 170                 width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 171                 break;
 172         case 2:
 173                 width = DMA_SLAVE_BUSWIDTH_2_BYTES;
 174                 break;
 175         default:
 176                 width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 177                 break;
 178         }
 179
 180         memset(&cfg, 0, sizeof(cfg));
 181         cfg.direction = dir;
 182
 183         if (dir == DMA_MEM_TO_DEV) {
 184                 cfg.dst_addr = drv_data->ssdr_physical;
 185                 cfg.dst_addr_width = width;
 186                 cfg.dst_maxburst = chip->dma_burst_size;
 187                 cfg.slave_id = pdata->tx_slave_id;
 188
 189                 sgt = &drv_data->tx_sgt;
 190                 nents = drv_data->tx_nents;
 191                 chan = drv_data->tx_chan;
 192         } else {
 193                 cfg.src_addr = drv_data->ssdr_physical;
 194                 cfg.src_addr_width = width;
 195                 cfg.src_maxburst = chip->dma_burst_size;
 196                 cfg.slave_id = pdata->rx_slave_id;
 197
 198                 sgt = &drv_data->rx_sgt;
 199                 nents = drv_data->rx_nents;
 200                 chan = drv_data->rx_chan;
 201         }
 202
 203         ret = dmaengine_slave_config(chan, &cfg);
 204         if (ret) {
 205                 dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n");
 206                 return NULL;
 207         }
 208
 209         return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir,
 210                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 211 }
 212
 213 static bool pxa2xx_spi_dma_filter(struct dma_chan *chan, void *param)
 214 {
 215         const struct pxa2xx_spi_master *pdata = param;
 216
 217         return chan->chan_id == pdata->tx_chan_id ||
 218                chan->chan_id == pdata->rx_chan_id;
 219 }
 220
 221 bool pxa2xx_spi_dma_is_possible(size_t len)
 222 {
 223         return len <= MAX_DMA_LEN;
 224 }
 225
 226 int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
 227 {
 228         const struct chip_data *chip = drv_data->cur_chip;
 229         int ret;
 230
 231         if (!chip->enable_dma)
 232                 return 0;
 233
 234         /* Don't bother with DMA if we can't do even a single burst */
 235         if (drv_data->len < chip->dma_burst_size)
 236                 return 0;
 237
 238         ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE);
 239         if (ret <= 0) {
 240                 dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n");
 241                 return 0;
 242         }
 243
 244         drv_data->tx_nents = ret;
 245
 246         ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE);
 247         if (ret <= 0) {
 248                 pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
 249                 dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n");
 250                 return 0;
 251         }
 252
 253         drv_data->rx_nents = ret;
 254         return 1;
 255 }
 256
 257 irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
 258 {
 259         u32 status;
 260
 261         status = read_SSSR(drv_data->ioaddr) & drv_data->mask_sr;
 262         if (status & SSSR_ROR) {
 263                 dev_err(&drv_data->pdev->dev, "FIFO overrun\n");
 264
 265                 dmaengine_terminate_all(drv_data->rx_chan);
 266                 dmaengine_terminate_all(drv_data->tx_chan);
 267
 268                 pxa2xx_spi_dma_transfer_complete(drv_data, true);
 269                 return IRQ_HANDLED;
 270         }
 271
 272         return IRQ_NONE;
 273 }
 274
 275 int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst)
 276 {
 277         struct dma_async_tx_descriptor *tx_desc, *rx_desc;
 278
 279         tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
 280         if (!tx_desc) {
 281                 dev_err(&drv_data->pdev->dev,
 282                         "failed to get DMA TX descriptor\n");
 283                 return -EBUSY;
 284         }
 285
 286         rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
 287         if (!rx_desc) {
 288                 dev_err(&drv_data->pdev->dev,
 289                         "failed to get DMA RX descriptor\n");
 290                 return -EBUSY;
 291         }
 292
 293         /* We are ready when RX completes */
 294         rx_desc->callback = pxa2xx_spi_dma_callback;
 295         rx_desc->callback_param = drv_data;
 296
 297         dmaengine_submit(rx_desc);
 298         dmaengine_submit(tx_desc);
 299         return 0;
 300 }
 301
 302 void pxa2xx_spi_dma_start(struct driver_data *drv_data)
 303 {
 304         dma_async_issue_pending(drv_data->rx_chan);
 305         dma_async_issue_pending(drv_data->tx_chan);
 306
 307         atomic_set(&drv_data->dma_running, 1);
 308 }
 309
 310 int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
 311 {
 312         struct pxa2xx_spi_master *pdata = drv_data->master_info;
 313         struct device *dev = &drv_data->pdev->dev;
 314         dma_cap_mask_t mask;
 315
 316         dma_cap_zero(mask);
 317         dma_cap_set(DMA_SLAVE, mask);
 318
 319         drv_data->dummy = devm_kzalloc(dev, SZ_2K, GFP_KERNEL);
 320         if (!drv_data->dummy)
 321                 return -ENOMEM;
 322
 323         drv_data->tx_chan = dma_request_slave_channel_compat(mask,
 324                                 pxa2xx_spi_dma_filter, pdata, dev, "tx");
 325         if (!drv_data->tx_chan)
 326                 return -ENODEV;
 327
 328         drv_data->rx_chan = dma_request_slave_channel_compat(mask,
 329                                 pxa2xx_spi_dma_filter, pdata, dev, "rx");
 330         if (!drv_data->rx_chan) {
 331                 dma_release_channel(drv_data->tx_chan);
 332                 drv_data->tx_chan = NULL;
 333                 return -ENODEV;
 334         }
 335
 336         return 0;
 337 }
 338
 339 void pxa2xx_spi_dma_release(struct driver_data *drv_data)
 340 {
 341         if (drv_data->rx_chan) {
 342                 dmaengine_terminate_all(drv_data->rx_chan);
 343                 dma_release_channel(drv_data->rx_chan);
 344                 sg_free_table(&drv_data->rx_sgt);
 345                 drv_data->rx_chan = NULL;
 346         }
 347         if (drv_data->tx_chan) {
 348                 dmaengine_terminate_all(drv_data->tx_chan);
 349                 dma_release_channel(drv_data->tx_chan);
 350                 sg_free_table(&drv_data->tx_sgt);
 351                 drv_data->tx_chan = NULL;
 352         }
 353 }
 354
 355 void pxa2xx_spi_dma_resume(struct driver_data *drv_data)
 356 {
 357 }
 358
 359 int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
 360                                            struct spi_device *spi,
 361                                            u8 bits_per_word, u32 *burst_code,
 362                                            u32 *threshold)
 363 {
 364         struct pxa2xx_spi_chip *chip_info = spi->controller_data;
 365
 366         /*
 367          * If the DMA burst size is given in chip_info we use that,
 368          * otherwise we use the default. Also we use the default FIFO
 369          * thresholds for now.
 370          */
 371         *burst_code = chip_info ? chip_info->dma_burst_size : 16;
 372         *threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
 373                    | SSCR1_TxTresh(TX_THRESH_DFLT);
 374
 375         return 0;
 376 }