drivers/spi/spi-pxa2xx-dma.c

   1 /*
   2  * PXA2xx SPI DMA engine support.
   3  *
   4  * Copyright (C) 2013, Intel Corporation
   5  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
   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/init.h>
  13 #include <linux/device.h>
  14 #include <linux/dma-mapping.h>
  15 #include <linux/dmaengine.h>
  16 #include <linux/pxa2xx_ssp.h>
  17 #include <linux/scatterlist.h>
  18 #include <linux/sizes.h>
  19 #include <linux/spi/spi.h>
  20 #include <linux/spi/pxa2xx_spi.h>
  21
  22 #include "spi-pxa2xx.h"
  23
  24 static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
  25                                      enum dma_data_direction dir)
  26 {
  27         int i, nents, len = drv_data->len;
  28         struct scatterlist *sg;
  29         struct device *dmadev;
  30         struct sg_table *sgt;
  31         void *buf, *pbuf;
  32
  33         /*
  34          * Some DMA controllers have problems transferring buffers that are
  35          * not multiple of 4 bytes. So we truncate the transfer so that it
  36          * is suitable for such controllers, and handle the trailing bytes
  37          * manually after the DMA completes.
  38          *
  39          * REVISIT: It would be better if this information could be
  40          * retrieved directly from the DMA device in a similar way than
  41          * ->copy_align etc. is done.
  42          */
  43         len = ALIGN(drv_data->len, 4);
  44
  45         if (dir == DMA_TO_DEVICE) {
  46                 dmadev = drv_data->tx_chan->device->dev;
  47                 sgt = &drv_data->tx_sgt;
  48                 buf = drv_data->tx;
  49                 drv_data->tx_map_len = len;
  50         } else {
  51                 dmadev = drv_data->rx_chan->device->dev;
  52                 sgt = &drv_data->rx_sgt;
  53                 buf = drv_data->rx;
  54                 drv_data->rx_map_len = len;
  55         }
  56
  57         nents = DIV_ROUND_UP(len, SZ_2K);
  58         if (nents != sgt->nents) {
  59                 int ret;
  60
  61                 sg_free_table(sgt);
  62                 ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
  63                 if (ret)
  64                         return ret;
  65         }
  66
  67         pbuf = buf;
  68         for_each_sg(sgt->sgl, sg, sgt->nents, i) {
  69                 size_t bytes = min_t(size_t, len, SZ_2K);
  70
  71                 if (buf)
  72                         sg_set_buf(sg, pbuf, bytes);
  73                 else
  74                         sg_set_buf(sg, drv_data->dummy, bytes);
  75
  76                 pbuf += bytes;
  77                 len -= bytes;
  78         }
  79
  80         nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir);
  81         if (!nents)
  82                 return -ENOMEM;
  83
  84         return nents;
  85 }
  86
  87 static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data,
  88                                         enum dma_data_direction dir)
  89 {
  90         struct device *dmadev;
  91         struct sg_table *sgt;
  92
  93         if (dir == DMA_TO_DEVICE) {
  94                 dmadev = drv_data->tx_chan->device->dev;
  95                 sgt = &drv_data->tx_sgt;
  96         } else {
  97                 dmadev = drv_data->rx_chan->device->dev;
  98                 sgt = &drv_data->rx_sgt;
  99         }
 100
 101         dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir);
 102 }
 103
 104 static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data)
 105 {
 106         if (!drv_data->dma_mapped)
 107                 return;
 108
 109         pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE);
 110         pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
 111
 112         drv_data->dma_mapped = 0;
 113 }
 114
 115 static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
 116                                              bool error)
 117 {
 118         struct spi_message *msg = drv_data->cur_msg;
 119
 120         /*
 121          * It is possible that one CPU is handling ROR interrupt and other
 122          * just gets DMA completion. Calling pump_transfers() twice for the
 123          * same transfer leads to problems thus we prevent concurrent calls
 124          * by using ->dma_running.
 125          */
 126         if (atomic_dec_and_test(&drv_data->dma_running)) {
 127                 void __iomem *reg = drv_data->ioaddr;
 128
 129                 /*
 130                  * If the other CPU is still handling the ROR interrupt we
 131                  * might not know about the error yet. So we re-check the
 132                  * ROR bit here before we clear the status register.
 133                  */
 134                 if (!error) {
 135                         u32 status = read_SSSR(reg) & drv_data->mask_sr;
 136                         error = status & SSSR_ROR;
 137                 }
 138
 139                 /* Clear status & disable interrupts */
 140                 write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg);
 141                 write_SSSR_CS(drv_data, drv_data->clear_sr);
 142                 if (!pxa25x_ssp_comp(drv_data))
 143                         write_SSTO(0, reg);
 144
 145                 if (!error) {
 146                         pxa2xx_spi_unmap_dma_buffers(drv_data);
 147
 148                         /* Handle the last bytes of unaligned transfer */
 149                         drv_data->tx += drv_data->tx_map_len;
 150                         drv_data->write(drv_data);
 151
 152                         drv_data->rx += drv_data->rx_map_len;
 153                         drv_data->read(drv_data);
 154
 155                         msg->actual_length += drv_data->len;
 156                         msg->state = pxa2xx_spi_next_transfer(drv_data);
 157                 } else {
 158                         /* In case we got an error we disable the SSP now */
 159                         write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);
 160
 161                         msg->state = ERROR_STATE;
 162                 }
 163
 164                 tasklet_schedule(&drv_data->pump_transfers);
 165         }
 166 }
 167
 168 static void pxa2xx_spi_dma_callback(void *data)
 169 {
 170         pxa2xx_spi_dma_transfer_complete(data, false);
 171 }
 172
 173 static struct dma_async_tx_descriptor *
 174 pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
 175                            enum dma_transfer_direction dir)
 176 {
 177         struct pxa2xx_spi_master *pdata = drv_data->master_info;
 178         struct chip_data *chip = drv_data->cur_chip;
 179         enum dma_slave_buswidth width;
 180         struct dma_slave_config cfg;
 181         struct dma_chan *chan;
 182         struct sg_table *sgt;
 183         int nents, ret;
 184
 185         switch (drv_data->n_bytes) {
 186         case 1:
 187                 width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 188                 break;
 189         case 2:
 190                 width = DMA_SLAVE_BUSWIDTH_2_BYTES;
 191                 break;
 192         default:
 193                 width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 194                 break;
 195         }
 196
 197         memset(&cfg, 0, sizeof(cfg));
 198         cfg.direction = dir;
 199
 200         if (dir == DMA_MEM_TO_DEV) {
 201                 cfg.dst_addr = drv_data->ssdr_physical;
 202                 cfg.dst_addr_width = width;
 203                 cfg.dst_maxburst = chip->dma_burst_size;
 204                 cfg.slave_id = pdata->tx_slave_id;
 205
 206                 sgt = &drv_data->tx_sgt;
 207                 nents = drv_data->tx_nents;
 208                 chan = drv_data->tx_chan;
 209         } else {
 210                 cfg.src_addr = drv_data->ssdr_physical;
 211                 cfg.src_addr_width = width;
 212                 cfg.src_maxburst = chip->dma_burst_size;
 213                 cfg.slave_id = pdata->rx_slave_id;
 214
 215                 sgt = &drv_data->rx_sgt;
 216                 nents = drv_data->rx_nents;
 217                 chan = drv_data->rx_chan;
 218         }
 219
 220         ret = dmaengine_slave_config(chan, &cfg);
 221         if (ret) {
 222                 dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n");
 223                 return NULL;
 224         }
 225
 226         return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir,
 227                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 228 }
 229
 230 static bool pxa2xx_spi_dma_filter(struct dma_chan *chan, void *param)
 231 {
 232         const struct pxa2xx_spi_master *pdata = param;
 233
 234         return chan->chan_id == pdata->tx_chan_id ||
 235                chan->chan_id == pdata->rx_chan_id;
 236 }
 237
 238 bool pxa2xx_spi_dma_is_possible(size_t len)
 239 {
 240         return len <= MAX_DMA_LEN;
 241 }
 242
 243 int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
 244 {
 245         const struct chip_data *chip = drv_data->cur_chip;
 246         int ret;
 247
 248         if (!chip->enable_dma)
 249                 return 0;
 250
 251         /* Don't bother with DMA if we can't do even a single burst */
 252         if (drv_data->len < chip->dma_burst_size)
 253                 return 0;
 254
 255         ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE);
 256         if (ret <= 0) {
 257                 dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n");
 258                 return 0;
 259         }
 260
 261         drv_data->tx_nents = ret;
 262
 263         ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE);
 264         if (ret <= 0) {
 265                 pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
 266                 dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n");
 267                 return 0;
 268         }
 269
 270         drv_data->rx_nents = ret;
 271         return 1;
 272 }
 273
 274 irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
 275 {
 276         u32 status;
 277
 278         status = read_SSSR(drv_data->ioaddr) & drv_data->mask_sr;
 279         if (status & SSSR_ROR) {
 280                 dev_err(&drv_data->pdev->dev, "FIFO overrun\n");
 281
 282                 dmaengine_terminate_all(drv_data->rx_chan);
 283                 dmaengine_terminate_all(drv_data->tx_chan);
 284
 285                 pxa2xx_spi_dma_transfer_complete(drv_data, true);
 286                 return IRQ_HANDLED;
 287         }
 288
 289         return IRQ_NONE;
 290 }
 291
 292 int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst)
 293 {
 294         struct dma_async_tx_descriptor *tx_desc, *rx_desc;
 295
 296         tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
 297         if (!tx_desc) {
 298                 dev_err(&drv_data->pdev->dev,
 299                         "failed to get DMA TX descriptor\n");
 300                 return -EBUSY;
 301         }
 302
 303         rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
 304         if (!rx_desc) {
 305                 dev_err(&drv_data->pdev->dev,
 306                         "failed to get DMA RX descriptor\n");
 307                 return -EBUSY;
 308         }
 309
 310         /* We are ready when RX completes */
 311         rx_desc->callback = pxa2xx_spi_dma_callback;
 312         rx_desc->callback_param = drv_data;
 313
 314         dmaengine_submit(rx_desc);
 315         dmaengine_submit(tx_desc);
 316         return 0;
 317 }
 318
 319 void pxa2xx_spi_dma_start(struct driver_data *drv_data)
 320 {
 321         dma_async_issue_pending(drv_data->rx_chan);
 322         dma_async_issue_pending(drv_data->tx_chan);
 323
 324         atomic_set(&drv_data->dma_running, 1);
 325 }
 326
 327 int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
 328 {
 329         struct pxa2xx_spi_master *pdata = drv_data->master_info;
 330         dma_cap_mask_t mask;
 331
 332         dma_cap_zero(mask);
 333         dma_cap_set(DMA_SLAVE, mask);
 334
 335         drv_data->dummy = devm_kzalloc(&drv_data->pdev->dev, SZ_2K, GFP_KERNEL);
 336         if (!drv_data->dummy)
 337                 return -ENOMEM;
 338
 339         drv_data->tx_chan = dma_request_channel(mask, pxa2xx_spi_dma_filter,
 340                                                 pdata);
 341         if (!drv_data->tx_chan)
 342                 return -ENODEV;
 343
 344         drv_data->rx_chan = dma_request_channel(mask, pxa2xx_spi_dma_filter,
 345                                                 pdata);
 346         if (!drv_data->rx_chan) {
 347                 dma_release_channel(drv_data->tx_chan);
 348                 drv_data->tx_chan = NULL;
 349                 return -ENODEV;
 350         }
 351
 352         return 0;
 353 }
 354
 355 void pxa2xx_spi_dma_release(struct driver_data *drv_data)
 356 {
 357         if (drv_data->rx_chan) {
 358                 dmaengine_terminate_all(drv_data->rx_chan);
 359                 dma_release_channel(drv_data->rx_chan);
 360                 sg_free_table(&drv_data->rx_sgt);
 361                 drv_data->rx_chan = NULL;
 362         }
 363         if (drv_data->tx_chan) {
 364                 dmaengine_terminate_all(drv_data->tx_chan);
 365                 dma_release_channel(drv_data->tx_chan);
 366                 sg_free_table(&drv_data->tx_sgt);
 367                 drv_data->tx_chan = NULL;
 368         }
 369 }
 370
 371 void pxa2xx_spi_dma_resume(struct driver_data *drv_data)
 372 {
 373 }
 374
 375 int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
 376                                            struct spi_device *spi,
 377                                            u8 bits_per_word, u32 *burst_code,
 378                                            u32 *threshold)
 379 {
 380         struct pxa2xx_spi_chip *chip_info = spi->controller_data;
 381
 382         /*
 383          * If the DMA burst size is given in chip_info we use that,
 384          * otherwise we use the default. Also we use the default FIFO
 385          * thresholds for now.
 386          */
 387         *burst_code = chip_info ? chip_info->dma_burst_size : 16;
 388         *threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
 389                    | SSCR1_TxTresh(TX_THRESH_DFLT);
 390
 391         return 0;
 392 }