target/linux/ramips/patches-4.3/0047-DMA-ralink-add-rt2880-dma-engine.patch

   1 From f1c4d9e622c800e1f38b3818f933ec7597d1ccfb Mon Sep 17 00:00:00 2001
   2 From: John Crispin <blogic@openwrt.org>
   3 Date: Sun, 27 Jul 2014 09:29:51 +0100
   4 Subject: [PATCH 47/53] DMA: ralink: add rt2880 dma engine
   5
   6 Signed-off-by: John Crispin <blogic@openwrt.org>
   7 ---
   8  drivers/dma/Kconfig       |    6 +
   9  drivers/dma/Makefile      |    1 +
  10  drivers/dma/ralink-gdma.c |  577 +++++++++++++++++++++++++++++++++++++++++++++
  11  include/linux/dmaengine.h |    1 +
  12  4 files changed, 585 insertions(+)
  13  create mode 100644 drivers/dma/ralink-gdma.c
  14
  15 diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
  16 index b458475..2d5ae4a 100644
  17 --- a/drivers/dma/Kconfig
  18 +++ b/drivers/dma/Kconfig
  19 @@ -40,6 +40,12 @@ config ASYNC_TX_ENABLE_CHANNEL_SWITCH
  20  config ARCH_HAS_ASYNC_TX_FIND_CHANNEL
  21         bool
  22
  23 +config DMA_RALINK
  24 +       tristate "RALINK DMA support"
  25 +       depends on RALINK && SOC_MT7620
  26 +       select DMA_ENGINE
  27 +       select DMA_VIRTUAL_CHANNELS
  28 +
  29  config DMA_ENGINE
  30         bool
  31
  32 diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
  33 index 7711a71..b33c434 100644
  34 --- a/drivers/dma/Makefile
  35 +++ b/drivers/dma/Makefile
  36 @@ -65,5 +65,6 @@ obj-$(CONFIG_TI_DMA_CROSSBAR) += ti-dma-crossbar.o
  37  obj-$(CONFIG_TI_EDMA) += edma.o
  38  obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
  39  obj-$(CONFIG_ZX_DMA) += zx296702_dma.o
  40 +obj-$(CONFIG_DMA_RALINK) += ralink-gdma.o
  41
  42  obj-y += xilinx/
  43 diff --git a/drivers/dma/ralink-gdma.c b/drivers/dma/ralink-gdma.c
  44 new file mode 100644
  45 index 0000000..2c3cace
  46 --- /dev/null
  47 +++ b/drivers/dma/ralink-gdma.c
  48 @@ -0,0 +1,577 @@
  49 +/*
  50 + *  Copyright (C) 2013, Lars-Peter Clausen <lars@metafoo.de>
  51 + *  GDMA4740 DMAC support
  52 + *
  53 + *  This program is free software; you can redistribute it and/or modify it
  54 + *  under  the terms of the GNU General         Public License as published by the
  55 + *  Free Software Foundation;  either version 2 of the License, or (at your
  56 + *  option) any later version.
  57 + *
  58 + *  You should have received a copy of the GNU General Public License along
  59 + *  with this program; if not, write to the Free Software Foundation, Inc.,
  60 + *  675 Mass Ave, Cambridge, MA 02139, USA.
  61 + *
  62 + */
  63 +
  64 +#include <linux/dmaengine.h>
  65 +#include <linux/dma-mapping.h>
  66 +#include <linux/err.h>
  67 +#include <linux/init.h>
  68 +#include <linux/list.h>
  69 +#include <linux/module.h>
  70 +#include <linux/platform_device.h>
  71 +#include <linux/slab.h>
  72 +#include <linux/spinlock.h>
  73 +#include <linux/irq.h>
  74 +#include <linux/of_dma.h>
  75 +
  76 +#include "virt-dma.h"
  77 +
  78 +#define GDMA_NR_CHANS                  16
  79 +
  80 +#define GDMA_REG_SRC_ADDR(x)           (0x00 + (x) * 0x10)
  81 +#define GDMA_REG_DST_ADDR(x)           (0x04 + (x) * 0x10)
  82 +
  83 +#define GDMA_REG_CTRL0(x)              (0x08 + (x) * 0x10)
  84 +#define GDMA_REG_CTRL0_TX_MASK         0xffff
  85 +#define GDMA_REG_CTRL0_TX_SHIFT                16
  86 +#define GDMA_REG_CTRL0_CURR_MASK       0xff
  87 +#define GDMA_REG_CTRL0_CURR_SHIFT      8
  88 +#define        GDMA_REG_CTRL0_SRC_ADDR_FIXED   BIT(7)
  89 +#define GDMA_REG_CTRL0_DST_ADDR_FIXED  BIT(6)
  90 +#define GDMA_REG_CTRL0_BURST_MASK      0x7
  91 +#define GDMA_REG_CTRL0_BURST_SHIFT     3
  92 +#define        GDMA_REG_CTRL0_DONE_INT         BIT(2)
  93 +#define        GDMA_REG_CTRL0_ENABLE           BIT(1)
  94 +#define        GDMA_REG_CTRL0_HW_MODE          0
  95 +
  96 +#define GDMA_REG_CTRL1(x)              (0x0c + (x) * 0x10)
  97 +#define GDMA_REG_CTRL1_SEG_MASK                0xf
  98 +#define GDMA_REG_CTRL1_SEG_SHIFT       22
  99 +#define GDMA_REG_CTRL1_REQ_MASK                0x3f
 100 +#define GDMA_REG_CTRL1_SRC_REQ_SHIFT   16
 101 +#define GDMA_REG_CTRL1_DST_REQ_SHIFT   8
 102 +#define GDMA_REG_CTRL1_CONTINOUS       BIT(14)
 103 +#define GDMA_REG_CTRL1_NEXT_MASK       0x1f
 104 +#define GDMA_REG_CTRL1_NEXT_SHIFT      3
 105 +#define GDMA_REG_CTRL1_COHERENT                BIT(2)
 106 +#define GDMA_REG_CTRL1_FAIL            BIT(1)
 107 +#define GDMA_REG_CTRL1_MASK            BIT(0)
 108 +
 109 +#define GDMA_REG_UNMASK_INT            0x200
 110 +#define GDMA_REG_DONE_INT              0x204
 111 +
 112 +#define GDMA_REG_GCT                   0x220
 113 +#define GDMA_REG_GCT_CHAN_MASK         0x3
 114 +#define GDMA_REG_GCT_CHAN_SHIFT                3
 115 +#define GDMA_REG_GCT_VER_MASK          0x3
 116 +#define GDMA_REG_GCT_VER_SHIFT         1
 117 +#define GDMA_REG_GCT_ARBIT_RR          BIT(0)
 118 +
 119 +enum gdma_dma_transfer_size {
 120 +       GDMA_TRANSFER_SIZE_4BYTE        = 0,
 121 +       GDMA_TRANSFER_SIZE_8BYTE        = 1,
 122 +       GDMA_TRANSFER_SIZE_16BYTE       = 2,
 123 +       GDMA_TRANSFER_SIZE_32BYTE       = 3,
 124 +};
 125 +
 126 +struct gdma_dma_sg {
 127 +       dma_addr_t addr;
 128 +       unsigned int len;
 129 +};
 130 +
 131 +struct gdma_dma_desc {
 132 +       struct virt_dma_desc vdesc;
 133 +
 134 +       enum dma_transfer_direction direction;
 135 +       bool cyclic;
 136 +
 137 +       unsigned int num_sgs;
 138 +       struct gdma_dma_sg sg[];
 139 +};
 140 +
 141 +struct gdma_dmaengine_chan {
 142 +       struct virt_dma_chan vchan;
 143 +       unsigned int id;
 144 +
 145 +       dma_addr_t fifo_addr;
 146 +       unsigned int transfer_shift;
 147 +
 148 +       struct gdma_dma_desc *desc;
 149 +       unsigned int next_sg;
 150 +};
 151 +
 152 +struct gdma_dma_dev {
 153 +       struct dma_device ddev;
 154 +       void __iomem *base;
 155 +       struct clk *clk;
 156 +
 157 +       struct gdma_dmaengine_chan chan[GDMA_NR_CHANS];
 158 +};
 159 +
 160 +static struct gdma_dma_dev *gdma_dma_chan_get_dev(
 161 +       struct gdma_dmaengine_chan *chan)
 162 +{
 163 +       return container_of(chan->vchan.chan.device, struct gdma_dma_dev,
 164 +               ddev);
 165 +}
 166 +
 167 +static struct gdma_dmaengine_chan *to_gdma_dma_chan(struct dma_chan *c)
 168 +{
 169 +       return container_of(c, struct gdma_dmaengine_chan, vchan.chan);
 170 +}
 171 +
 172 +static struct gdma_dma_desc *to_gdma_dma_desc(struct virt_dma_desc *vdesc)
 173 +{
 174 +       return container_of(vdesc, struct gdma_dma_desc, vdesc);
 175 +}
 176 +
 177 +static inline uint32_t gdma_dma_read(struct gdma_dma_dev *dma_dev,
 178 +       unsigned int reg)
 179 +{
 180 +       return readl(dma_dev->base + reg);
 181 +}
 182 +
 183 +static inline void gdma_dma_write(struct gdma_dma_dev *dma_dev,
 184 +       unsigned reg, uint32_t val)
 185 +{
 186 +       //printk("gdma --> %p = 0x%08X\n", dma_dev->base + reg, val);
 187 +       writel(val, dma_dev->base + reg);
 188 +}
 189 +
 190 +static inline void gdma_dma_write_mask(struct gdma_dma_dev *dma_dev,
 191 +       unsigned int reg, uint32_t val, uint32_t mask)
 192 +{
 193 +       uint32_t tmp;
 194 +
 195 +       tmp = gdma_dma_read(dma_dev, reg);
 196 +       tmp &= ~mask;
 197 +       tmp |= val;
 198 +       gdma_dma_write(dma_dev, reg, tmp);
 199 +}
 200 +
 201 +static struct gdma_dma_desc *gdma_dma_alloc_desc(unsigned int num_sgs)
 202 +{
 203 +       return kzalloc(sizeof(struct gdma_dma_desc) +
 204 +               sizeof(struct gdma_dma_sg) * num_sgs, GFP_ATOMIC);
 205 +}
 206 +
 207 +static enum gdma_dma_transfer_size gdma_dma_maxburst(u32 maxburst)
 208 +{
 209 +       if (maxburst <= 7)
 210 +               return GDMA_TRANSFER_SIZE_4BYTE;
 211 +       else if (maxburst <= 15)
 212 +               return GDMA_TRANSFER_SIZE_8BYTE;
 213 +       else if (maxburst <= 31)
 214 +               return GDMA_TRANSFER_SIZE_16BYTE;
 215 +
 216 +       return GDMA_TRANSFER_SIZE_32BYTE;
 217 +}
 218 +
 219 +static int gdma_dma_slave_config(struct dma_chan *c,
 220 +       const struct dma_slave_config *config)
 221 +{
 222 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 223 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 224 +       enum gdma_dma_transfer_size transfer_size;
 225 +       uint32_t flags;
 226 +       uint32_t ctrl0, ctrl1;
 227 +
 228 +       switch (config->direction) {
 229 +       case DMA_MEM_TO_DEV:
 230 +               ctrl1 = 32 << GDMA_REG_CTRL1_SRC_REQ_SHIFT;
 231 +               ctrl1 |= config->slave_id << GDMA_REG_CTRL1_DST_REQ_SHIFT;
 232 +               flags = GDMA_REG_CTRL0_DST_ADDR_FIXED;
 233 +               transfer_size = gdma_dma_maxburst(config->dst_maxburst);
 234 +               chan->fifo_addr = config->dst_addr;
 235 +               break;
 236 +
 237 +       case DMA_DEV_TO_MEM:
 238 +               ctrl1 = config->slave_id << GDMA_REG_CTRL1_SRC_REQ_SHIFT;
 239 +               ctrl1 |= 32 << GDMA_REG_CTRL1_DST_REQ_SHIFT;
 240 +               flags = GDMA_REG_CTRL0_SRC_ADDR_FIXED;
 241 +               transfer_size = gdma_dma_maxburst(config->src_maxburst);
 242 +               chan->fifo_addr = config->src_addr;
 243 +               break;
 244 +
 245 +       default:
 246 +               return -EINVAL;
 247 +       }
 248 +
 249 +       chan->transfer_shift = 1 + transfer_size;
 250 +
 251 +       ctrl0 = flags | GDMA_REG_CTRL0_HW_MODE;
 252 +       ctrl0 |= GDMA_REG_CTRL0_DONE_INT;
 253 +
 254 +       ctrl1 &= ~(GDMA_REG_CTRL1_NEXT_MASK << GDMA_REG_CTRL1_NEXT_SHIFT);
 255 +       ctrl1 |= chan->id << GDMA_REG_CTRL1_NEXT_SHIFT;
 256 +       ctrl1 |= GDMA_REG_CTRL1_FAIL;
 257 +       ctrl1 &= ~GDMA_REG_CTRL1_CONTINOUS;
 258 +       gdma_dma_write(dma_dev, GDMA_REG_CTRL0(chan->id), ctrl0);
 259 +       gdma_dma_write(dma_dev, GDMA_REG_CTRL1(chan->id), ctrl1);
 260 +
 261 +       return 0;
 262 +}
 263 +
 264 +static int gdma_dma_terminate_all(struct dma_chan *c)
 265 +{
 266 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 267 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 268 +       unsigned long flags;
 269 +       LIST_HEAD(head);
 270 +
 271 +       spin_lock_irqsave(&chan->vchan.lock, flags);
 272 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL0(chan->id), 0,
 273 +                       GDMA_REG_CTRL0_ENABLE);
 274 +       chan->desc = NULL;
 275 +       vchan_get_all_descriptors(&chan->vchan, &head);
 276 +       spin_unlock_irqrestore(&chan->vchan.lock, flags);
 277 +
 278 +       vchan_dma_desc_free_list(&chan->vchan, &head);
 279 +
 280 +       return 0;
 281 +}
 282 +
 283 +static int gdma_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
 284 +       unsigned long arg)
 285 +{
 286 +       struct dma_slave_config *config = (struct dma_slave_config *)arg;
 287 +
 288 +       switch (cmd) {
 289 +       case DMA_SLAVE_CONFIG:
 290 +               return gdma_dma_slave_config(chan, config);
 291 +       case DMA_TERMINATE_ALL:
 292 +               return gdma_dma_terminate_all(chan);
 293 +       default:
 294 +               return -ENOSYS;
 295 +       }
 296 +}
 297 +
 298 +static int gdma_dma_start_transfer(struct gdma_dmaengine_chan *chan)
 299 +{
 300 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 301 +       dma_addr_t src_addr, dst_addr;
 302 +       struct virt_dma_desc *vdesc;
 303 +       struct gdma_dma_sg *sg;
 304 +
 305 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL0(chan->id), 0,
 306 +                       GDMA_REG_CTRL0_ENABLE);
 307 +
 308 +       if (!chan->desc) {
 309 +               vdesc = vchan_next_desc(&chan->vchan);
 310 +               if (!vdesc)
 311 +                       return 0;
 312 +               chan->desc = to_gdma_dma_desc(vdesc);
 313 +               chan->next_sg = 0;
 314 +       }
 315 +
 316 +       if (chan->next_sg == chan->desc->num_sgs)
 317 +               chan->next_sg = 0;
 318 +
 319 +       sg = &chan->desc->sg[chan->next_sg];
 320 +
 321 +       if (chan->desc->direction == DMA_MEM_TO_DEV) {
 322 +               src_addr = sg->addr;
 323 +               dst_addr = chan->fifo_addr;
 324 +       } else {
 325 +               src_addr = chan->fifo_addr;
 326 +               dst_addr = sg->addr;
 327 +       }
 328 +       gdma_dma_write(dma_dev, GDMA_REG_SRC_ADDR(chan->id), src_addr);
 329 +       gdma_dma_write(dma_dev, GDMA_REG_DST_ADDR(chan->id), dst_addr);
 330 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL0(chan->id),
 331 +                       (sg->len << GDMA_REG_CTRL0_TX_SHIFT) | GDMA_REG_CTRL0_ENABLE,
 332 +                       GDMA_REG_CTRL0_TX_MASK << GDMA_REG_CTRL0_TX_SHIFT);
 333 +       chan->next_sg++;
 334 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL1(chan->id), 0, GDMA_REG_CTRL1_MASK);
 335 +
 336 +       return 0;
 337 +}
 338 +
 339 +static void gdma_dma_chan_irq(struct gdma_dmaengine_chan *chan)
 340 +{
 341 +       spin_lock(&chan->vchan.lock);
 342 +       if (chan->desc) {
 343 +               if (chan->desc && chan->desc->cyclic) {
 344 +                       vchan_cyclic_callback(&chan->desc->vdesc);
 345 +               } else {
 346 +                       if (chan->next_sg == chan->desc->num_sgs) {
 347 +                               chan->desc = NULL;
 348 +                               vchan_cookie_complete(&chan->desc->vdesc);
 349 +                       }
 350 +               }
 351 +       }
 352 +       gdma_dma_start_transfer(chan);
 353 +       spin_unlock(&chan->vchan.lock);
 354 +}
 355 +
 356 +static irqreturn_t gdma_dma_irq(int irq, void *devid)
 357 +{
 358 +       struct gdma_dma_dev *dma_dev = devid;
 359 +       uint32_t unmask, done;
 360 +       unsigned int i;
 361 +
 362 +       unmask = gdma_dma_read(dma_dev, GDMA_REG_UNMASK_INT);
 363 +       gdma_dma_write(dma_dev, GDMA_REG_UNMASK_INT, unmask);
 364 +       done = gdma_dma_read(dma_dev, GDMA_REG_DONE_INT);
 365 +
 366 +       for (i = 0; i < GDMA_NR_CHANS; ++i)
 367 +               if (done & BIT(i))
 368 +                       gdma_dma_chan_irq(&dma_dev->chan[i]);
 369 +       gdma_dma_write(dma_dev, GDMA_REG_DONE_INT, done);
 370 +
 371 +       return IRQ_HANDLED;
 372 +}
 373 +
 374 +static void gdma_dma_issue_pending(struct dma_chan *c)
 375 +{
 376 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 377 +       unsigned long flags;
 378 +
 379 +       spin_lock_irqsave(&chan->vchan.lock, flags);
 380 +       if (vchan_issue_pending(&chan->vchan) && !chan->desc)
 381 +               gdma_dma_start_transfer(chan);
 382 +       spin_unlock_irqrestore(&chan->vchan.lock, flags);
 383 +}
 384 +
 385 +static struct dma_async_tx_descriptor *gdma_dma_prep_slave_sg(
 386 +       struct dma_chan *c, struct scatterlist *sgl,
 387 +       unsigned int sg_len, enum dma_transfer_direction direction,
 388 +       unsigned long flags, void *context)
 389 +{
 390 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 391 +       struct gdma_dma_desc *desc;
 392 +       struct scatterlist *sg;
 393 +       unsigned int i;
 394 +
 395 +       desc = gdma_dma_alloc_desc(sg_len);
 396 +       if (!desc)
 397 +               return NULL;
 398 +
 399 +       for_each_sg(sgl, sg, sg_len, i) {
 400 +               desc->sg[i].addr = sg_dma_address(sg);
 401 +               desc->sg[i].len = sg_dma_len(sg);
 402 +       }
 403 +
 404 +       desc->num_sgs = sg_len;
 405 +       desc->direction = direction;
 406 +       desc->cyclic = false;
 407 +
 408 +       return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
 409 +}
 410 +
 411 +static struct dma_async_tx_descriptor *gdma_dma_prep_dma_cyclic(
 412 +       struct dma_chan *c, dma_addr_t buf_addr, size_t buf_len,
 413 +       size_t period_len, enum dma_transfer_direction direction,
 414 +       unsigned long flags, void *context)
 415 +{
 416 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 417 +       struct gdma_dma_desc *desc;
 418 +       unsigned int num_periods, i;
 419 +
 420 +       if (buf_len % period_len)
 421 +               return NULL;
 422 +
 423 +       num_periods = buf_len / period_len;
 424 +
 425 +       desc = gdma_dma_alloc_desc(num_periods);
 426 +       if (!desc)
 427 +               return NULL;
 428 +
 429 +       for (i = 0; i < num_periods; i++) {
 430 +               desc->sg[i].addr = buf_addr;
 431 +               desc->sg[i].len = period_len;
 432 +               buf_addr += period_len;
 433 +       }
 434 +
 435 +       desc->num_sgs = num_periods;
 436 +       desc->direction = direction;
 437 +       desc->cyclic = true;
 438 +
 439 +       return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
 440 +}
 441 +
 442 +static size_t gdma_dma_desc_residue(struct gdma_dmaengine_chan *chan,
 443 +       struct gdma_dma_desc *desc, unsigned int next_sg)
 444 +{
 445 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 446 +       unsigned int residue, count;
 447 +       unsigned int i;
 448 +
 449 +       residue = 0;
 450 +
 451 +       for (i = next_sg; i < desc->num_sgs; i++)
 452 +               residue += desc->sg[i].len;
 453 +
 454 +       if (next_sg != 0) {
 455 +               count = gdma_dma_read(dma_dev, GDMA_REG_CTRL0(chan->id));
 456 +               count >>= GDMA_REG_CTRL0_CURR_SHIFT;
 457 +               count &= GDMA_REG_CTRL0_CURR_MASK;
 458 +               residue += count << chan->transfer_shift;
 459 +       }
 460 +
 461 +       return residue;
 462 +}
 463 +
 464 +static enum dma_status gdma_dma_tx_status(struct dma_chan *c,
 465 +       dma_cookie_t cookie, struct dma_tx_state *state)
 466 +{
 467 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 468 +       struct virt_dma_desc *vdesc;
 469 +       enum dma_status status;
 470 +       unsigned long flags;
 471 +
 472 +       status = dma_cookie_status(c, cookie, state);
 473 +       if (status == DMA_SUCCESS || !state)
 474 +               return status;
 475 +
 476 +       spin_lock_irqsave(&chan->vchan.lock, flags);
 477 +       vdesc = vchan_find_desc(&chan->vchan, cookie);
 478 +       if (cookie == chan->desc->vdesc.tx.cookie) {
 479 +               state->residue = gdma_dma_desc_residue(chan, chan->desc,
 480 +                               chan->next_sg);
 481 +       } else if (vdesc) {
 482 +               state->residue = gdma_dma_desc_residue(chan,
 483 +                               to_gdma_dma_desc(vdesc), 0);
 484 +       } else {
 485 +               state->residue = 0;
 486 +       }
 487 +       spin_unlock_irqrestore(&chan->vchan.lock, flags);
 488 +
 489 +       return status;
 490 +}
 491 +
 492 +static int gdma_dma_alloc_chan_resources(struct dma_chan *c)
 493 +{
 494 +       return 0;
 495 +}
 496 +
 497 +static void gdma_dma_free_chan_resources(struct dma_chan *c)
 498 +{
 499 +       vchan_free_chan_resources(to_virt_chan(c));
 500 +}
 501 +
 502 +static void gdma_dma_desc_free(struct virt_dma_desc *vdesc)
 503 +{
 504 +       kfree(container_of(vdesc, struct gdma_dma_desc, vdesc));
 505 +}
 506 +
 507 +static struct dma_chan *
 508 +of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
 509 +                       struct of_dma *ofdma)
 510 +{
 511 +       struct gdma_dma_dev *dma_dev = ofdma->of_dma_data;
 512 +       unsigned int request = dma_spec->args[0];
 513 +
 514 +       if (request >= GDMA_NR_CHANS)
 515 +               return NULL;
 516 +
 517 +       return dma_get_slave_channel(&(dma_dev->chan[request].vchan.chan));
 518 +}
 519 +
 520 +static int gdma_dma_probe(struct platform_device *pdev)
 521 +{
 522 +       struct gdma_dmaengine_chan *chan;
 523 +       struct gdma_dma_dev *dma_dev;
 524 +       struct dma_device *dd;
 525 +       unsigned int i;
 526 +       struct resource *res;
 527 +       uint32_t gct;
 528 +       int ret;
 529 +       int irq;
 530 +
 531 +
 532 +       dma_dev = devm_kzalloc(&pdev->dev, sizeof(*dma_dev), GFP_KERNEL);
 533 +       if (!dma_dev)
 534 +               return -EINVAL;
 535 +
 536 +       dd = &dma_dev->ddev;
 537 +
 538 +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 539 +       dma_dev->base = devm_ioremap_resource(&pdev->dev, res);
 540 +       if (IS_ERR(dma_dev->base))
 541 +               return PTR_ERR(dma_dev->base);
 542 +
 543 +       dma_cap_set(DMA_SLAVE, dd->cap_mask);
 544 +       dma_cap_set(DMA_CYCLIC, dd->cap_mask);
 545 +       dd->device_alloc_chan_resources = gdma_dma_alloc_chan_resources;
 546 +       dd->device_free_chan_resources = gdma_dma_free_chan_resources;
 547 +       dd->device_tx_status = gdma_dma_tx_status;
 548 +       dd->device_issue_pending = gdma_dma_issue_pending;
 549 +       dd->device_prep_slave_sg = gdma_dma_prep_slave_sg;
 550 +       dd->device_prep_dma_cyclic = gdma_dma_prep_dma_cyclic;
 551 +       dd->device_control = gdma_dma_control;
 552 +       dd->dev = &pdev->dev;
 553 +       dd->chancnt = GDMA_NR_CHANS;
 554 +       INIT_LIST_HEAD(&dd->channels);
 555 +
 556 +       for (i = 0; i < dd->chancnt; i++) {
 557 +               chan = &dma_dev->chan[i];
 558 +               chan->id = i;
 559 +               chan->vchan.desc_free = gdma_dma_desc_free;
 560 +               vchan_init(&chan->vchan, dd);
 561 +       }
 562 +
 563 +       ret = dma_async_device_register(dd);
 564 +       if (ret)
 565 +               return ret;
 566 +
 567 +       ret = of_dma_controller_register(pdev->dev.of_node,
 568 +               of_dma_xlate_by_chan_id, dma_dev);
 569 +       if (ret)
 570 +               goto err_unregister;
 571 +
 572 +       irq = platform_get_irq(pdev, 0);
 573 +       ret = request_irq(irq, gdma_dma_irq, 0, dev_name(&pdev->dev), dma_dev);
 574 +       if (ret)
 575 +               goto err_unregister;
 576 +
 577 +       gdma_dma_write(dma_dev, GDMA_REG_UNMASK_INT, 0);
 578 +       gdma_dma_write(dma_dev, GDMA_REG_DONE_INT, BIT(dd->chancnt) - 1);
 579 +
 580 +       gct = gdma_dma_read(dma_dev, GDMA_REG_GCT);
 581 +       dev_info(&pdev->dev, "revision: %d, channels: %d\n",
 582 +               (gct >> GDMA_REG_GCT_VER_SHIFT) & GDMA_REG_GCT_VER_MASK,
 583 +               8 << ((gct >> GDMA_REG_GCT_CHAN_SHIFT) & GDMA_REG_GCT_CHAN_MASK));
 584 +       platform_set_drvdata(pdev, dma_dev);
 585 +
 586 +       gdma_dma_write(dma_dev, GDMA_REG_GCT, GDMA_REG_GCT_ARBIT_RR);
 587 +
 588 +       return 0;
 589 +
 590 +err_unregister:
 591 +       dma_async_device_unregister(dd);
 592 +       return ret;
 593 +}
 594 +
 595 +static int gdma_dma_remove(struct platform_device *pdev)
 596 +{
 597 +       struct gdma_dma_dev *dma_dev = platform_get_drvdata(pdev);
 598 +       int irq = platform_get_irq(pdev, 0);
 599 +
 600 +       free_irq(irq, dma_dev);
 601 +        of_dma_controller_free(pdev->dev.of_node);
 602 +       dma_async_device_unregister(&dma_dev->ddev);
 603 +
 604 +       return 0;
 605 +}
 606 +
 607 +static const struct of_device_id gdma_of_match_table[] = {
 608 +       { .compatible = "ralink,rt2880-gdma" },
 609 +       { },
 610 +};
 611 +
 612 +static struct platform_driver gdma_dma_driver = {
 613 +       .probe = gdma_dma_probe,
 614 +       .remove = gdma_dma_remove,
 615 +       .driver = {
 616 +               .name = "gdma-rt2880",
 617 +               .owner = THIS_MODULE,
 618 +               .of_match_table = gdma_of_match_table,
 619 +       },
 620 +};
 621 +module_platform_driver(gdma_dma_driver);
 622 +
 623 +MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 624 +MODULE_DESCRIPTION("GDMA4740 DMA driver");
 625 +MODULE_LICENSE("GPLv2");
 626 diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
 627 index 7ea9184..d371bf1 100644
 628 --- a/include/linux/dmaengine.h
 629 +++ b/include/linux/dmaengine.h
 630 @@ -496,6 +496,7 @@ static inline void dma_set_unmap(struct dma_async_tx_descriptor *tx,
 631  struct dmaengine_unmap_data *
 632  dmaengine_get_unmap_data(struct device *dev, int nr, gfp_t flags);
 633  void dmaengine_unmap_put(struct dmaengine_unmap_data *unmap);
 634 +struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
 635  #else
 636  static inline void dma_set_unmap(struct dma_async_tx_descriptor *tx,
 637                                  struct dmaengine_unmap_data *unmap)
 638 --
 639 1.7.10.4
 640