target/linux/brcm2708/patches-4.4/0020-dmaengine-bcm2835-Add-slave-dma-support.patch

   1 From dc5b926436bccc4efbb1695ec3696b5db6746d3b Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
   3 Date: Thu, 9 Apr 2015 12:34:11 +0200
   4 Subject: [PATCH 020/170] dmaengine: bcm2835: Add slave dma support
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Add slave transfer capability to BCM2835 dmaengine driver.
  10 This patch is pulled from the bcm2708-dmaengine driver in the
  11 Raspberry Pi repo. The work was done by Gellert Weisz.
  12
  13 Tested using the bcm2835-mmc driver from the same repo.
  14
  15 Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
  16 ---
  17  drivers/dma/bcm2835-dma.c | 206 ++++++++++++++++++++++++++++++++++++++++++----
  18  1 file changed, 192 insertions(+), 14 deletions(-)
  19
  20 --- a/drivers/dma/bcm2835-dma.c
  21 +++ b/drivers/dma/bcm2835-dma.c
  22 @@ -1,11 +1,10 @@
  23  /*
  24   * BCM2835 DMA engine support
  25   *
  26 - * This driver only supports cyclic DMA transfers
  27 - * as needed for the I2S module.
  28 - *
  29   * Author:      Florian Meier <florian.meier@koalo.de>
  30   *              Copyright 2013
  31 + *              Gellert Weisz <gellert@raspberrypi.org>
  32 + *              Copyright 2013-2014
  33   *
  34   * Based on
  35   *     OMAP DMAengine support by Russell King
  36 @@ -95,6 +94,8 @@ struct bcm2835_desc {
  37         size_t size;
  38  };
  39
  40 +#define BCM2835_DMA_WAIT_CYCLES        0  /* Slow down DMA transfers: 0-31 */
  41 +
  42  #define BCM2835_DMA_CS         0x00
  43  #define BCM2835_DMA_ADDR       0x04
  44  #define BCM2835_DMA_SOURCE_AD  0x0c
  45 @@ -111,12 +112,16 @@ struct bcm2835_desc {
  46  #define BCM2835_DMA_RESET      BIT(31) /* WO, self clearing */
  47
  48  #define BCM2835_DMA_INT_EN     BIT(0)
  49 +#define BCM2835_DMA_WAIT_RESP  BIT(3)
  50  #define BCM2835_DMA_D_INC      BIT(4)
  51 +#define BCM2835_DMA_D_WIDTH    BIT(5)
  52  #define BCM2835_DMA_D_DREQ     BIT(6)
  53  #define BCM2835_DMA_S_INC      BIT(8)
  54 +#define BCM2835_DMA_S_WIDTH    BIT(9)
  55  #define BCM2835_DMA_S_DREQ     BIT(10)
  56
  57  #define BCM2835_DMA_PER_MAP(x) ((x) << 16)
  58 +#define BCM2835_DMA_WAITS(x)   (((x) & 0x1f) << 21)
  59
  60  #define BCM2835_DMA_DATA_TYPE_S8       1
  61  #define BCM2835_DMA_DATA_TYPE_S16      2
  62 @@ -130,6 +135,14 @@ struct bcm2835_desc {
  63  #define BCM2835_DMA_CHAN(n)    ((n) << 8) /* Base address */
  64  #define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n))
  65
  66 +#define MAX_NORMAL_TRANSFER    SZ_1G
  67 +/*
  68 + * Max length on a Lite channel is 65535 bytes.
  69 + * DMA handles byte-enables on SDRAM reads and writes even on 128-bit accesses,
  70 + * but byte-enables don't exist on peripheral addresses, so align to 32-bit.
  71 + */
  72 +#define MAX_LITE_TRANSFER      (SZ_64K - 4)
  73 +
  74  static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
  75  {
  76         return container_of(d, struct bcm2835_dmadev, ddev);
  77 @@ -226,12 +239,18 @@ static irqreturn_t bcm2835_dma_callback(
  78         d = c->desc;
  79
  80         if (d) {
  81 -               /* TODO Only works for cyclic DMA */
  82 -               vchan_cyclic_callback(&d->vd);
  83 -       }
  84 +               if (c->cyclic) {
  85 +                       vchan_cyclic_callback(&d->vd);
  86
  87 -       /* Keep the DMA engine running */
  88 -       writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
  89 +                       /* Keep the DMA engine running */
  90 +                       writel(BCM2835_DMA_ACTIVE,
  91 +                              c->chan_base + BCM2835_DMA_CS);
  92 +
  93 +               } else {
  94 +                       vchan_cookie_complete(&c->desc->vd);
  95 +                       bcm2835_dma_start_desc(c);
  96 +               }
  97 +       }
  98
  99         spin_unlock_irqrestore(&c->vc.lock, flags);
 100
 101 @@ -339,8 +358,6 @@ static void bcm2835_dma_issue_pending(st
 102         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 103         unsigned long flags;
 104
 105 -       c->cyclic = true; /* Nothing else is implemented */
 106 -
 107         spin_lock_irqsave(&c->vc.lock, flags);
 108         if (vchan_issue_pending(&c->vc) && !c->desc)
 109                 bcm2835_dma_start_desc(c);
 110 @@ -358,7 +375,7 @@ static struct dma_async_tx_descriptor *b
 111         struct bcm2835_desc *d;
 112         dma_addr_t dev_addr;
 113         unsigned int es, sync_type;
 114 -       unsigned int frame;
 115 +       unsigned int frame, max_size;
 116         int i;
 117
 118         /* Grab configuration */
 119 @@ -393,7 +410,12 @@ static struct dma_async_tx_descriptor *b
 120
 121         d->c = c;
 122         d->dir = direction;
 123 -       d->frames = buf_len / period_len;
 124 +       if (c->ch >= 8) /* LITE channel */
 125 +               max_size = MAX_LITE_TRANSFER;
 126 +       else
 127 +               max_size = MAX_NORMAL_TRANSFER;
 128 +       period_len = min(period_len, max_size);
 129 +       d->frames = (buf_len - 1) / (period_len + 1);
 130
 131         d->cb_list = kcalloc(d->frames, sizeof(*d->cb_list), GFP_KERNEL);
 132         if (!d->cb_list) {
 133 @@ -441,17 +463,171 @@ static struct dma_async_tx_descriptor *b
 134                                 BCM2835_DMA_PER_MAP(c->dreq);
 135
 136                 /* Length of a frame */
 137 -               control_block->length = period_len;
 138 +               if (frame != d->frames - 1)
 139 +                       control_block->length = period_len;
 140 +               else
 141 +                       control_block->length = buf_len - (d->frames - 1) *
 142 +                                               period_len;
 143                 d->size += control_block->length;
 144
 145                 /*
 146                  * Next block is the next frame.
 147 -                * This DMA engine driver currently only supports cyclic DMA.
 148 +                * This function is called on cyclic DMA transfers.
 149                  * Therefore, wrap around at number of frames.
 150                  */
 151                 control_block->next = d->cb_list[((frame + 1) % d->frames)].paddr;
 152         }
 153
 154 +       c->cyclic = true;
 155 +
 156 +       return vchan_tx_prep(&c->vc, &d->vd, flags);
 157 +}
 158 +
 159 +static struct dma_async_tx_descriptor *
 160 +bcm2835_dma_prep_slave_sg(struct dma_chan *chan,
 161 +                         struct scatterlist *sgl,
 162 +                         unsigned int sg_len,
 163 +                         enum dma_transfer_direction direction,
 164 +                         unsigned long flags, void *context)
 165 +{
 166 +       struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 167 +       enum dma_slave_buswidth dev_width;
 168 +       struct bcm2835_desc *d;
 169 +       dma_addr_t dev_addr;
 170 +       struct scatterlist *sgent;
 171 +       unsigned int i, sync_type, split_cnt, max_size;
 172 +
 173 +       if (!is_slave_direction(direction)) {
 174 +               dev_err(chan->device->dev, "direction not supported\n");
 175 +               return NULL;
 176 +       }
 177 +
 178 +       if (direction == DMA_DEV_TO_MEM) {
 179 +               dev_addr = c->cfg.src_addr;
 180 +               dev_width = c->cfg.src_addr_width;
 181 +               sync_type = BCM2835_DMA_S_DREQ;
 182 +       } else {
 183 +               dev_addr = c->cfg.dst_addr;
 184 +               dev_width = c->cfg.dst_addr_width;
 185 +               sync_type = BCM2835_DMA_D_DREQ;
 186 +       }
 187 +
 188 +       /* Bus width translates to the element size (ES) */
 189 +       switch (dev_width) {
 190 +       case DMA_SLAVE_BUSWIDTH_4_BYTES:
 191 +               break;
 192 +       default:
 193 +               dev_err(chan->device->dev, "buswidth not supported: %i\n",
 194 +                       dev_width);
 195 +               return NULL;
 196 +       }
 197 +
 198 +       /* Allocate and setup the descriptor. */
 199 +       d = kzalloc(sizeof(*d), GFP_NOWAIT);
 200 +       if (!d)
 201 +               return NULL;
 202 +
 203 +       d->dir = direction;
 204 +
 205 +       if (c->ch >= 8) /* LITE channel */
 206 +               max_size = MAX_LITE_TRANSFER;
 207 +       else
 208 +               max_size = MAX_NORMAL_TRANSFER;
 209 +
 210 +       /*
 211 +        * Store the length of the SG list in d->frames
 212 +        * taking care to account for splitting up transfers
 213 +        * too large for a LITE channel
 214 +        */
 215 +       d->frames = 0;
 216 +       for_each_sg(sgl, sgent, sg_len, i) {
 217 +               unsigned int len = sg_dma_len(sgent);
 218 +
 219 +               d->frames += len / max_size + 1;
 220 +       }
 221 +
 222 +       /* Allocate memory for control blocks */
 223 +       d->control_block_size = d->frames * sizeof(struct bcm2835_dma_cb);
 224 +       d->control_block_base = dma_zalloc_coherent(chan->device->dev,
 225 +                       d->control_block_size, &d->control_block_base_phys,
 226 +                       GFP_NOWAIT);
 227 +       if (!d->control_block_base) {
 228 +               kfree(d);
 229 +               return NULL;
 230 +       }
 231 +
 232 +       /*
 233 +        * Iterate over all SG entries, create a control block
 234 +        * for each frame and link them together.
 235 +        * Count the number of times an SG entry had to be split
 236 +        * as a result of using a LITE channel
 237 +        */
 238 +       split_cnt = 0;
 239 +
 240 +       for_each_sg(sgl, sgent, sg_len, i) {
 241 +               unsigned int j;
 242 +               dma_addr_t addr = sg_dma_address(sgent);
 243 +               unsigned int len = sg_dma_len(sgent);
 244 +
 245 +               for (j = 0; j < len; j += max_size) {
 246 +                       struct bcm2835_dma_cb *control_block =
 247 +                               &d->control_block_base[i + split_cnt];
 248 +
 249 +                       /* Setup addresses */
 250 +                       if (d->dir == DMA_DEV_TO_MEM) {
 251 +                               control_block->info = BCM2835_DMA_D_INC |
 252 +                                                     BCM2835_DMA_D_WIDTH |
 253 +                                                     BCM2835_DMA_S_DREQ;
 254 +                               control_block->src = dev_addr;
 255 +                               control_block->dst = addr + (dma_addr_t)j;
 256 +                       } else {
 257 +                               control_block->info = BCM2835_DMA_S_INC |
 258 +                                                     BCM2835_DMA_S_WIDTH |
 259 +                                                     BCM2835_DMA_D_DREQ;
 260 +                               control_block->src = addr + (dma_addr_t)j;
 261 +                               control_block->dst = dev_addr;
 262 +                       }
 263 +
 264 +                       /* Common part */
 265 +                       control_block->info |=
 266 +                               BCM2835_DMA_WAITS(BCM2835_DMA_WAIT_CYCLES);
 267 +                       control_block->info |= BCM2835_DMA_WAIT_RESP;
 268 +
 269 +                       /* Enable */
 270 +                       if (i == sg_len - 1 && len - j <= max_size)
 271 +                               control_block->info |= BCM2835_DMA_INT_EN;
 272 +
 273 +                       /* Setup synchronization */
 274 +                       if (sync_type)
 275 +                               control_block->info |= sync_type;
 276 +
 277 +                       /* Setup DREQ channel */
 278 +                       if (c->dreq)
 279 +                               control_block->info |=
 280 +                                       BCM2835_DMA_PER_MAP(c->dreq);
 281 +
 282 +                       /* Length of a frame */
 283 +                       control_block->length = min(len - j, max_size);
 284 +                       d->size += control_block->length;
 285 +
 286 +                       if (i < sg_len - 1 || len - j > max_size) {
 287 +                               /* Next block is the next frame. */
 288 +                               control_block->next =
 289 +                                       d->control_block_base_phys +
 290 +                                       sizeof(struct bcm2835_dma_cb) *
 291 +                                       (i + split_cnt + 1);
 292 +                       } else {
 293 +                               /* Next block is empty. */
 294 +                               control_block->next = 0;
 295 +                       }
 296 +
 297 +                       if (len - j > max_size)
 298 +                               split_cnt++;
 299 +               }
 300 +       }
 301 +
 302 +       c->cyclic = false;
 303 +
 304         return vchan_tx_prep(&c->vc, &d->vd, flags);
 305  error_cb:
 306         i--;
 307 @@ -620,6 +796,7 @@ static int bcm2835_dma_probe(struct plat
 308         od->ddev.device_tx_status = bcm2835_dma_tx_status;
 309         od->ddev.device_issue_pending = bcm2835_dma_issue_pending;
 310         od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic;
 311 +       od->ddev.device_prep_slave_sg = bcm2835_dma_prep_slave_sg;
 312         od->ddev.device_config = bcm2835_dma_slave_config;
 313         od->ddev.device_terminate_all = bcm2835_dma_terminate_all;
 314         od->ddev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
 315 @@ -708,4 +885,5 @@ module_platform_driver(bcm2835_dma_drive
 316  MODULE_ALIAS("platform:bcm2835-dma");
 317  MODULE_DESCRIPTION("BCM2835 DMA engine driver");
 318  MODULE_AUTHOR("Florian Meier <florian.meier@koalo.de>");
 319 +MODULE_AUTHOR("Gellert Weisz <gellert@raspberrypi.org>");
 320  MODULE_LICENSE("GPL v2");