target/linux/ramips/patches-3.14/0054-DMA-ralink-add-rt2880-dma-engine.patch

   1 From cf93418a4bd5e69f069a65da92537bd4d6191223 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 54/57] 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/dmaengine.c   |   26 ++
  11  drivers/dma/ralink-gdma.c |  577 +++++++++++++++++++++++++++++++++++++++++++++
  12  include/linux/dmaengine.h |    1 +
  13  5 files changed, 611 insertions(+)
  14  create mode 100644 drivers/dma/ralink-gdma.c
  15
  16 --- a/drivers/dma/Kconfig
  17 +++ b/drivers/dma/Kconfig
  18 @@ -351,6 +351,12 @@ config MOXART_DMA
  19         help
  20           Enable support for the MOXA ART SoC DMA controller.
  21
  22 +config DMA_RALINK
  23 +       tristate "RALINK DMA support"
  24 +       depends on RALINK && SOC_MT7620
  25 +       select DMA_ENGINE
  26 +       select DMA_VIRTUAL_CHANNELS
  27 +
  28  config DMA_ENGINE
  29         bool
  30
  31 --- a/drivers/dma/Makefile
  32 +++ b/drivers/dma/Makefile
  33 @@ -44,3 +44,4 @@ obj-$(CONFIG_DMA_JZ4740) += dma-jz4740.o
  34  obj-$(CONFIG_TI_CPPI41) += cppi41.o
  35  obj-$(CONFIG_K3_DMA) += k3dma.o
  36  obj-$(CONFIG_MOXART_DMA) += moxart-dma.o
  37 +obj-$(CONFIG_DMA_RALINK) += ralink-gdma.o
  38 --- a/drivers/dma/dmaengine.c
  39 +++ b/drivers/dma/dmaengine.c
  40 @@ -564,6 +564,32 @@ struct dma_chan *dma_get_any_slave_chann
  41  EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
  42
  43  /**
  44 + * dma_request_slave_channel - try to get specific channel exclusively
  45 + * @chan: target channel
  46 + */
  47 +struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
  48 +{
  49 +       int err = -EBUSY;
  50 +
  51 +       /* lock against __dma_request_channel */
  52 +       mutex_lock(&dma_list_mutex);
  53 +
  54 +       if (chan->client_count == 0) {
  55 +               err = dma_chan_get(chan);
  56 +               if (err)
  57 +                       pr_debug("%s: failed to get %s: (%d)\n",
  58 +                               __func__, dma_chan_name(chan), err);
  59 +       } else
  60 +               chan = NULL;
  61 +
  62 +       mutex_unlock(&dma_list_mutex);
  63 +
  64 +       return chan;
  65 +}
  66 +EXPORT_SYMBOL_GPL(dma_get_slave_channel);
  67 +
  68 +
  69 +/**
  70   * __dma_request_channel - try to allocate an exclusive channel
  71   * @mask: capabilities that the channel must satisfy
  72   * @fn: optional callback to disposition available channels
  73 --- /dev/null
  74 +++ b/drivers/dma/ralink-gdma.c
  75 @@ -0,0 +1,577 @@
  76 +/*
  77 + *  Copyright (C) 2013, Lars-Peter Clausen <lars@metafoo.de>
  78 + *  GDMA4740 DMAC support
  79 + *
  80 + *  This program is free software; you can redistribute it and/or modify it
  81 + *  under  the terms of the GNU General         Public License as published by the
  82 + *  Free Software Foundation;  either version 2 of the License, or (at your
  83 + *  option) any later version.
  84 + *
  85 + *  You should have received a copy of the GNU General Public License along
  86 + *  with this program; if not, write to the Free Software Foundation, Inc.,
  87 + *  675 Mass Ave, Cambridge, MA 02139, USA.
  88 + *
  89 + */
  90 +
  91 +#include <linux/dmaengine.h>
  92 +#include <linux/dma-mapping.h>
  93 +#include <linux/err.h>
  94 +#include <linux/init.h>
  95 +#include <linux/list.h>
  96 +#include <linux/module.h>
  97 +#include <linux/platform_device.h>
  98 +#include <linux/slab.h>
  99 +#include <linux/spinlock.h>
 100 +#include <linux/irq.h>
 101 +#include <linux/of_dma.h>
 102 +
 103 +#include "virt-dma.h"
 104 +
 105 +#define GDMA_NR_CHANS                  16
 106 +
 107 +#define GDMA_REG_SRC_ADDR(x)           (0x00 + (x) * 0x10)
 108 +#define GDMA_REG_DST_ADDR(x)           (0x04 + (x) * 0x10)
 109 +
 110 +#define GDMA_REG_CTRL0(x)              (0x08 + (x) * 0x10)
 111 +#define GDMA_REG_CTRL0_TX_MASK         0xffff
 112 +#define GDMA_REG_CTRL0_TX_SHIFT                16
 113 +#define GDMA_REG_CTRL0_CURR_MASK       0xff
 114 +#define GDMA_REG_CTRL0_CURR_SHIFT      8
 115 +#define        GDMA_REG_CTRL0_SRC_ADDR_FIXED   BIT(7)
 116 +#define GDMA_REG_CTRL0_DST_ADDR_FIXED  BIT(6)
 117 +#define GDMA_REG_CTRL0_BURST_MASK      0x7
 118 +#define GDMA_REG_CTRL0_BURST_SHIFT     3
 119 +#define        GDMA_REG_CTRL0_DONE_INT         BIT(2)
 120 +#define        GDMA_REG_CTRL0_ENABLE           BIT(1)
 121 +#define        GDMA_REG_CTRL0_HW_MODE          0
 122 +
 123 +#define GDMA_REG_CTRL1(x)              (0x0c + (x) * 0x10)
 124 +#define GDMA_REG_CTRL1_SEG_MASK                0xf
 125 +#define GDMA_REG_CTRL1_SEG_SHIFT       22
 126 +#define GDMA_REG_CTRL1_REQ_MASK                0x3f
 127 +#define GDMA_REG_CTRL1_SRC_REQ_SHIFT   16
 128 +#define GDMA_REG_CTRL1_DST_REQ_SHIFT   8
 129 +#define GDMA_REG_CTRL1_CONTINOUS       BIT(14)
 130 +#define GDMA_REG_CTRL1_NEXT_MASK       0x1f
 131 +#define GDMA_REG_CTRL1_NEXT_SHIFT      3
 132 +#define GDMA_REG_CTRL1_COHERENT                BIT(2)
 133 +#define GDMA_REG_CTRL1_FAIL            BIT(1)
 134 +#define GDMA_REG_CTRL1_MASK            BIT(0)
 135 +
 136 +#define GDMA_REG_UNMASK_INT            0x200
 137 +#define GDMA_REG_DONE_INT              0x204
 138 +
 139 +#define GDMA_REG_GCT                   0x220
 140 +#define GDMA_REG_GCT_CHAN_MASK         0x3
 141 +#define GDMA_REG_GCT_CHAN_SHIFT                3
 142 +#define GDMA_REG_GCT_VER_MASK          0x3
 143 +#define GDMA_REG_GCT_VER_SHIFT         1
 144 +#define GDMA_REG_GCT_ARBIT_RR          BIT(0)
 145 +
 146 +enum gdma_dma_transfer_size {
 147 +       GDMA_TRANSFER_SIZE_4BYTE        = 0,
 148 +       GDMA_TRANSFER_SIZE_8BYTE        = 1,
 149 +       GDMA_TRANSFER_SIZE_16BYTE       = 2,
 150 +       GDMA_TRANSFER_SIZE_32BYTE       = 3,
 151 +};
 152 +
 153 +struct gdma_dma_sg {
 154 +       dma_addr_t addr;
 155 +       unsigned int len;
 156 +};
 157 +
 158 +struct gdma_dma_desc {
 159 +       struct virt_dma_desc vdesc;
 160 +
 161 +       enum dma_transfer_direction direction;
 162 +       bool cyclic;
 163 +
 164 +       unsigned int num_sgs;
 165 +       struct gdma_dma_sg sg[];
 166 +};
 167 +
 168 +struct gdma_dmaengine_chan {
 169 +       struct virt_dma_chan vchan;
 170 +       unsigned int id;
 171 +
 172 +       dma_addr_t fifo_addr;
 173 +       unsigned int transfer_shift;
 174 +
 175 +       struct gdma_dma_desc *desc;
 176 +       unsigned int next_sg;
 177 +};
 178 +
 179 +struct gdma_dma_dev {
 180 +       struct dma_device ddev;
 181 +       void __iomem *base;
 182 +       struct clk *clk;
 183 +
 184 +       struct gdma_dmaengine_chan chan[GDMA_NR_CHANS];
 185 +};
 186 +
 187 +static struct gdma_dma_dev *gdma_dma_chan_get_dev(
 188 +       struct gdma_dmaengine_chan *chan)
 189 +{
 190 +       return container_of(chan->vchan.chan.device, struct gdma_dma_dev,
 191 +               ddev);
 192 +}
 193 +
 194 +static struct gdma_dmaengine_chan *to_gdma_dma_chan(struct dma_chan *c)
 195 +{
 196 +       return container_of(c, struct gdma_dmaengine_chan, vchan.chan);
 197 +}
 198 +
 199 +static struct gdma_dma_desc *to_gdma_dma_desc(struct virt_dma_desc *vdesc)
 200 +{
 201 +       return container_of(vdesc, struct gdma_dma_desc, vdesc);
 202 +}
 203 +
 204 +static inline uint32_t gdma_dma_read(struct gdma_dma_dev *dma_dev,
 205 +       unsigned int reg)
 206 +{
 207 +       return readl(dma_dev->base + reg);
 208 +}
 209 +
 210 +static inline void gdma_dma_write(struct gdma_dma_dev *dma_dev,
 211 +       unsigned reg, uint32_t val)
 212 +{
 213 +       //printk("gdma --> %p = 0x%08X\n", dma_dev->base + reg, val);
 214 +       writel(val, dma_dev->base + reg);
 215 +}
 216 +
 217 +static inline void gdma_dma_write_mask(struct gdma_dma_dev *dma_dev,
 218 +       unsigned int reg, uint32_t val, uint32_t mask)
 219 +{
 220 +       uint32_t tmp;
 221 +
 222 +       tmp = gdma_dma_read(dma_dev, reg);
 223 +       tmp &= ~mask;
 224 +       tmp |= val;
 225 +       gdma_dma_write(dma_dev, reg, tmp);
 226 +}
 227 +
 228 +static struct gdma_dma_desc *gdma_dma_alloc_desc(unsigned int num_sgs)
 229 +{
 230 +       return kzalloc(sizeof(struct gdma_dma_desc) +
 231 +               sizeof(struct gdma_dma_sg) * num_sgs, GFP_ATOMIC);
 232 +}
 233 +
 234 +static enum gdma_dma_transfer_size gdma_dma_maxburst(u32 maxburst)
 235 +{
 236 +       if (maxburst <= 7)
 237 +               return GDMA_TRANSFER_SIZE_4BYTE;
 238 +       else if (maxburst <= 15)
 239 +               return GDMA_TRANSFER_SIZE_8BYTE;
 240 +       else if (maxburst <= 31)
 241 +               return GDMA_TRANSFER_SIZE_16BYTE;
 242 +
 243 +       return GDMA_TRANSFER_SIZE_32BYTE;
 244 +}
 245 +
 246 +static int gdma_dma_slave_config(struct dma_chan *c,
 247 +       const struct dma_slave_config *config)
 248 +{
 249 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 250 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 251 +       enum gdma_dma_transfer_size transfer_size;
 252 +       uint32_t flags;
 253 +       uint32_t ctrl0, ctrl1;
 254 +
 255 +       switch (config->direction) {
 256 +       case DMA_MEM_TO_DEV:
 257 +               ctrl1 = 32 << GDMA_REG_CTRL1_SRC_REQ_SHIFT;
 258 +               ctrl1 |= config->slave_id << GDMA_REG_CTRL1_DST_REQ_SHIFT;
 259 +               flags = GDMA_REG_CTRL0_DST_ADDR_FIXED;
 260 +               transfer_size = gdma_dma_maxburst(config->dst_maxburst);
 261 +               chan->fifo_addr = config->dst_addr;
 262 +               break;
 263 +
 264 +       case DMA_DEV_TO_MEM:
 265 +               ctrl1 = config->slave_id << GDMA_REG_CTRL1_SRC_REQ_SHIFT;
 266 +               ctrl1 |= 32 << GDMA_REG_CTRL1_DST_REQ_SHIFT;
 267 +               flags = GDMA_REG_CTRL0_SRC_ADDR_FIXED;
 268 +               transfer_size = gdma_dma_maxburst(config->src_maxburst);
 269 +               chan->fifo_addr = config->src_addr;
 270 +               break;
 271 +
 272 +       default:
 273 +               return -EINVAL;
 274 +       }
 275 +
 276 +       chan->transfer_shift = 1 + transfer_size;
 277 +
 278 +       ctrl0 = flags | GDMA_REG_CTRL0_HW_MODE;
 279 +       ctrl0 |= GDMA_REG_CTRL0_DONE_INT;
 280 +
 281 +       ctrl1 &= ~(GDMA_REG_CTRL1_NEXT_MASK << GDMA_REG_CTRL1_NEXT_SHIFT);
 282 +       ctrl1 |= chan->id << GDMA_REG_CTRL1_NEXT_SHIFT;
 283 +       ctrl1 |= GDMA_REG_CTRL1_FAIL;
 284 +       ctrl1 &= ~GDMA_REG_CTRL1_CONTINOUS;
 285 +       gdma_dma_write(dma_dev, GDMA_REG_CTRL0(chan->id), ctrl0);
 286 +       gdma_dma_write(dma_dev, GDMA_REG_CTRL1(chan->id), ctrl1);
 287 +
 288 +       return 0;
 289 +}
 290 +
 291 +static int gdma_dma_terminate_all(struct dma_chan *c)
 292 +{
 293 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 294 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 295 +       unsigned long flags;
 296 +       LIST_HEAD(head);
 297 +
 298 +       spin_lock_irqsave(&chan->vchan.lock, flags);
 299 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL0(chan->id), 0,
 300 +                       GDMA_REG_CTRL0_ENABLE);
 301 +       chan->desc = NULL;
 302 +       vchan_get_all_descriptors(&chan->vchan, &head);
 303 +       spin_unlock_irqrestore(&chan->vchan.lock, flags);
 304 +
 305 +       vchan_dma_desc_free_list(&chan->vchan, &head);
 306 +
 307 +       return 0;
 308 +}
 309 +
 310 +static int gdma_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
 311 +       unsigned long arg)
 312 +{
 313 +       struct dma_slave_config *config = (struct dma_slave_config *)arg;
 314 +
 315 +       switch (cmd) {
 316 +       case DMA_SLAVE_CONFIG:
 317 +               return gdma_dma_slave_config(chan, config);
 318 +       case DMA_TERMINATE_ALL:
 319 +               return gdma_dma_terminate_all(chan);
 320 +       default:
 321 +               return -ENOSYS;
 322 +       }
 323 +}
 324 +
 325 +static int gdma_dma_start_transfer(struct gdma_dmaengine_chan *chan)
 326 +{
 327 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 328 +       dma_addr_t src_addr, dst_addr;
 329 +       struct virt_dma_desc *vdesc;
 330 +       struct gdma_dma_sg *sg;
 331 +
 332 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL0(chan->id), 0,
 333 +                       GDMA_REG_CTRL0_ENABLE);
 334 +
 335 +       if (!chan->desc) {
 336 +               vdesc = vchan_next_desc(&chan->vchan);
 337 +               if (!vdesc)
 338 +                       return 0;
 339 +               chan->desc = to_gdma_dma_desc(vdesc);
 340 +               chan->next_sg = 0;
 341 +       }
 342 +
 343 +       if (chan->next_sg == chan->desc->num_sgs)
 344 +               chan->next_sg = 0;
 345 +
 346 +       sg = &chan->desc->sg[chan->next_sg];
 347 +
 348 +       if (chan->desc->direction == DMA_MEM_TO_DEV) {
 349 +               src_addr = sg->addr;
 350 +               dst_addr = chan->fifo_addr;
 351 +       } else {
 352 +               src_addr = chan->fifo_addr;
 353 +               dst_addr = sg->addr;
 354 +       }
 355 +       gdma_dma_write(dma_dev, GDMA_REG_SRC_ADDR(chan->id), src_addr);
 356 +       gdma_dma_write(dma_dev, GDMA_REG_DST_ADDR(chan->id), dst_addr);
 357 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL0(chan->id),
 358 +                       (sg->len << GDMA_REG_CTRL0_TX_SHIFT) | GDMA_REG_CTRL0_ENABLE,
 359 +                       GDMA_REG_CTRL0_TX_MASK << GDMA_REG_CTRL0_TX_SHIFT);
 360 +       chan->next_sg++;
 361 +       gdma_dma_write_mask(dma_dev, GDMA_REG_CTRL1(chan->id), 0, GDMA_REG_CTRL1_MASK);
 362 +
 363 +       return 0;
 364 +}
 365 +
 366 +static void gdma_dma_chan_irq(struct gdma_dmaengine_chan *chan)
 367 +{
 368 +       spin_lock(&chan->vchan.lock);
 369 +       if (chan->desc) {
 370 +               if (chan->desc && chan->desc->cyclic) {
 371 +                       vchan_cyclic_callback(&chan->desc->vdesc);
 372 +               } else {
 373 +                       if (chan->next_sg == chan->desc->num_sgs) {
 374 +                               chan->desc = NULL;
 375 +                               vchan_cookie_complete(&chan->desc->vdesc);
 376 +                       }
 377 +               }
 378 +       }
 379 +       gdma_dma_start_transfer(chan);
 380 +       spin_unlock(&chan->vchan.lock);
 381 +}
 382 +
 383 +static irqreturn_t gdma_dma_irq(int irq, void *devid)
 384 +{
 385 +       struct gdma_dma_dev *dma_dev = devid;
 386 +       uint32_t unmask, done;
 387 +       unsigned int i;
 388 +
 389 +       unmask = gdma_dma_read(dma_dev, GDMA_REG_UNMASK_INT);
 390 +       gdma_dma_write(dma_dev, GDMA_REG_UNMASK_INT, unmask);
 391 +       done = gdma_dma_read(dma_dev, GDMA_REG_DONE_INT);
 392 +
 393 +       for (i = 0; i < GDMA_NR_CHANS; ++i)
 394 +               if (done & BIT(i))
 395 +                       gdma_dma_chan_irq(&dma_dev->chan[i]);
 396 +       gdma_dma_write(dma_dev, GDMA_REG_DONE_INT, done);
 397 +
 398 +       return IRQ_HANDLED;
 399 +}
 400 +
 401 +static void gdma_dma_issue_pending(struct dma_chan *c)
 402 +{
 403 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 404 +       unsigned long flags;
 405 +
 406 +       spin_lock_irqsave(&chan->vchan.lock, flags);
 407 +       if (vchan_issue_pending(&chan->vchan) && !chan->desc)
 408 +               gdma_dma_start_transfer(chan);
 409 +       spin_unlock_irqrestore(&chan->vchan.lock, flags);
 410 +}
 411 +
 412 +static struct dma_async_tx_descriptor *gdma_dma_prep_slave_sg(
 413 +       struct dma_chan *c, struct scatterlist *sgl,
 414 +       unsigned int sg_len, enum dma_transfer_direction direction,
 415 +       unsigned long flags, void *context)
 416 +{
 417 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 418 +       struct gdma_dma_desc *desc;
 419 +       struct scatterlist *sg;
 420 +       unsigned int i;
 421 +
 422 +       desc = gdma_dma_alloc_desc(sg_len);
 423 +       if (!desc)
 424 +               return NULL;
 425 +
 426 +       for_each_sg(sgl, sg, sg_len, i) {
 427 +               desc->sg[i].addr = sg_dma_address(sg);
 428 +               desc->sg[i].len = sg_dma_len(sg);
 429 +       }
 430 +
 431 +       desc->num_sgs = sg_len;
 432 +       desc->direction = direction;
 433 +       desc->cyclic = false;
 434 +
 435 +       return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
 436 +}
 437 +
 438 +static struct dma_async_tx_descriptor *gdma_dma_prep_dma_cyclic(
 439 +       struct dma_chan *c, dma_addr_t buf_addr, size_t buf_len,
 440 +       size_t period_len, enum dma_transfer_direction direction,
 441 +       unsigned long flags, void *context)
 442 +{
 443 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 444 +       struct gdma_dma_desc *desc;
 445 +       unsigned int num_periods, i;
 446 +
 447 +       if (buf_len % period_len)
 448 +               return NULL;
 449 +
 450 +       num_periods = buf_len / period_len;
 451 +
 452 +       desc = gdma_dma_alloc_desc(num_periods);
 453 +       if (!desc)
 454 +               return NULL;
 455 +
 456 +       for (i = 0; i < num_periods; i++) {
 457 +               desc->sg[i].addr = buf_addr;
 458 +               desc->sg[i].len = period_len;
 459 +               buf_addr += period_len;
 460 +       }
 461 +
 462 +       desc->num_sgs = num_periods;
 463 +       desc->direction = direction;
 464 +       desc->cyclic = true;
 465 +
 466 +       return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
 467 +}
 468 +
 469 +static size_t gdma_dma_desc_residue(struct gdma_dmaengine_chan *chan,
 470 +       struct gdma_dma_desc *desc, unsigned int next_sg)
 471 +{
 472 +       struct gdma_dma_dev *dma_dev = gdma_dma_chan_get_dev(chan);
 473 +       unsigned int residue, count;
 474 +       unsigned int i;
 475 +
 476 +       residue = 0;
 477 +
 478 +       for (i = next_sg; i < desc->num_sgs; i++)
 479 +               residue += desc->sg[i].len;
 480 +
 481 +       if (next_sg != 0) {
 482 +               count = gdma_dma_read(dma_dev, GDMA_REG_CTRL0(chan->id));
 483 +               count >>= GDMA_REG_CTRL0_CURR_SHIFT;
 484 +               count &= GDMA_REG_CTRL0_CURR_MASK;
 485 +               residue += count << chan->transfer_shift;
 486 +       }
 487 +
 488 +       return residue;
 489 +}
 490 +
 491 +static enum dma_status gdma_dma_tx_status(struct dma_chan *c,
 492 +       dma_cookie_t cookie, struct dma_tx_state *state)
 493 +{
 494 +       struct gdma_dmaengine_chan *chan = to_gdma_dma_chan(c);
 495 +       struct virt_dma_desc *vdesc;
 496 +       enum dma_status status;
 497 +       unsigned long flags;
 498 +
 499 +       status = dma_cookie_status(c, cookie, state);
 500 +       if (status == DMA_SUCCESS || !state)
 501 +               return status;
 502 +
 503 +       spin_lock_irqsave(&chan->vchan.lock, flags);
 504 +       vdesc = vchan_find_desc(&chan->vchan, cookie);
 505 +       if (cookie == chan->desc->vdesc.tx.cookie) {
 506 +               state->residue = gdma_dma_desc_residue(chan, chan->desc,
 507 +                               chan->next_sg);
 508 +       } else if (vdesc) {
 509 +               state->residue = gdma_dma_desc_residue(chan,
 510 +                               to_gdma_dma_desc(vdesc), 0);
 511 +       } else {
 512 +               state->residue = 0;
 513 +       }
 514 +       spin_unlock_irqrestore(&chan->vchan.lock, flags);
 515 +
 516 +       return status;
 517 +}
 518 +
 519 +static int gdma_dma_alloc_chan_resources(struct dma_chan *c)
 520 +{
 521 +       return 0;
 522 +}
 523 +
 524 +static void gdma_dma_free_chan_resources(struct dma_chan *c)
 525 +{
 526 +       vchan_free_chan_resources(to_virt_chan(c));
 527 +}
 528 +
 529 +static void gdma_dma_desc_free(struct virt_dma_desc *vdesc)
 530 +{
 531 +       kfree(container_of(vdesc, struct gdma_dma_desc, vdesc));
 532 +}
 533 +
 534 +static struct dma_chan *
 535 +of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
 536 +                       struct of_dma *ofdma)
 537 +{
 538 +       struct gdma_dma_dev *dma_dev = ofdma->of_dma_data;
 539 +       unsigned int request = dma_spec->args[0];
 540 +
 541 +       if (request >= GDMA_NR_CHANS)
 542 +               return NULL;
 543 +
 544 +       return dma_get_slave_channel(&(dma_dev->chan[request].vchan.chan));
 545 +}
 546 +
 547 +static int gdma_dma_probe(struct platform_device *pdev)
 548 +{
 549 +       struct gdma_dmaengine_chan *chan;
 550 +       struct gdma_dma_dev *dma_dev;
 551 +       struct dma_device *dd;
 552 +       unsigned int i;
 553 +       struct resource *res;
 554 +       uint32_t gct;
 555 +       int ret;
 556 +       int irq;
 557 +
 558 +
 559 +       dma_dev = devm_kzalloc(&pdev->dev, sizeof(*dma_dev), GFP_KERNEL);
 560 +       if (!dma_dev)
 561 +               return -EINVAL;
 562 +
 563 +       dd = &dma_dev->ddev;
 564 +
 565 +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 566 +       dma_dev->base = devm_ioremap_resource(&pdev->dev, res);
 567 +       if (IS_ERR(dma_dev->base))
 568 +               return PTR_ERR(dma_dev->base);
 569 +
 570 +       dma_cap_set(DMA_SLAVE, dd->cap_mask);
 571 +       dma_cap_set(DMA_CYCLIC, dd->cap_mask);
 572 +       dd->device_alloc_chan_resources = gdma_dma_alloc_chan_resources;
 573 +       dd->device_free_chan_resources = gdma_dma_free_chan_resources;
 574 +       dd->device_tx_status = gdma_dma_tx_status;
 575 +       dd->device_issue_pending = gdma_dma_issue_pending;
 576 +       dd->device_prep_slave_sg = gdma_dma_prep_slave_sg;
 577 +       dd->device_prep_dma_cyclic = gdma_dma_prep_dma_cyclic;
 578 +       dd->device_control = gdma_dma_control;
 579 +       dd->dev = &pdev->dev;
 580 +       dd->chancnt = GDMA_NR_CHANS;
 581 +       INIT_LIST_HEAD(&dd->channels);
 582 +
 583 +       for (i = 0; i < dd->chancnt; i++) {
 584 +               chan = &dma_dev->chan[i];
 585 +               chan->id = i;
 586 +               chan->vchan.desc_free = gdma_dma_desc_free;
 587 +               vchan_init(&chan->vchan, dd);
 588 +       }
 589 +
 590 +       ret = dma_async_device_register(dd);
 591 +       if (ret)
 592 +               return ret;
 593 +
 594 +       ret = of_dma_controller_register(pdev->dev.of_node,
 595 +               of_dma_xlate_by_chan_id, dma_dev);
 596 +       if (ret)
 597 +               goto err_unregister;
 598 +
 599 +       irq = platform_get_irq(pdev, 0);
 600 +       ret = request_irq(irq, gdma_dma_irq, 0, dev_name(&pdev->dev), dma_dev);
 601 +       if (ret)
 602 +               goto err_unregister;
 603 +
 604 +       gdma_dma_write(dma_dev, GDMA_REG_UNMASK_INT, 0);
 605 +       gdma_dma_write(dma_dev, GDMA_REG_DONE_INT, BIT(dd->chancnt) - 1);
 606 +
 607 +       gct = gdma_dma_read(dma_dev, GDMA_REG_GCT);
 608 +       dev_info(&pdev->dev, "revision: %d, channels: %d\n",
 609 +               (gct >> GDMA_REG_GCT_VER_SHIFT) & GDMA_REG_GCT_VER_MASK,
 610 +               8 << ((gct >> GDMA_REG_GCT_CHAN_SHIFT) & GDMA_REG_GCT_CHAN_MASK));
 611 +       platform_set_drvdata(pdev, dma_dev);
 612 +
 613 +       gdma_dma_write(dma_dev, GDMA_REG_GCT, GDMA_REG_GCT_ARBIT_RR);
 614 +
 615 +       return 0;
 616 +
 617 +err_unregister:
 618 +       dma_async_device_unregister(dd);
 619 +       return ret;
 620 +}
 621 +
 622 +static int gdma_dma_remove(struct platform_device *pdev)
 623 +{
 624 +       struct gdma_dma_dev *dma_dev = platform_get_drvdata(pdev);
 625 +       int irq = platform_get_irq(pdev, 0);
 626 +
 627 +       free_irq(irq, dma_dev);
 628 +        of_dma_controller_free(pdev->dev.of_node);
 629 +       dma_async_device_unregister(&dma_dev->ddev);
 630 +
 631 +       return 0;
 632 +}
 633 +
 634 +static const struct of_device_id gdma_of_match_table[] = {
 635 +       { .compatible = "ralink,rt2880-gdma" },
 636 +       { },
 637 +};
 638 +
 639 +static struct platform_driver gdma_dma_driver = {
 640 +       .probe = gdma_dma_probe,
 641 +       .remove = gdma_dma_remove,
 642 +       .driver = {
 643 +               .name = "gdma-rt2880",
 644 +               .owner = THIS_MODULE,
 645 +               .of_match_table = gdma_of_match_table,
 646 +       },
 647 +};
 648 +module_platform_driver(gdma_dma_driver);
 649 +
 650 +MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 651 +MODULE_DESCRIPTION("GDMA4740 DMA driver");
 652 +MODULE_LICENSE("GPLv2");
 653 --- a/include/linux/dmaengine.h
 654 +++ b/include/linux/dmaengine.h
 655 @@ -1073,6 +1073,7 @@ struct dma_chan *dma_request_slave_chann
 656                                                   const char *name);
 657  struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name);
 658  void dma_release_channel(struct dma_chan *chan);
 659 +struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
 660  #else
 661  static inline struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
 662  {