drivers/dma/bcm2835-dma.c

   1 /*
   2  * BCM2835 DMA engine support
   3  *
   4  * This driver only supports cyclic DMA transfers
   5  * as needed for the I2S module.
   6  *
   7  * Author:      Florian Meier <florian.meier@koalo.de>
   8  *              Copyright 2013
   9  *
  10  * Based on
  11  *      OMAP DMAengine support by Russell King
  12  *
  13  *      BCM2708 DMA Driver
  14  *      Copyright (C) 2010 Broadcom
  15  *
  16  *      Raspberry Pi PCM I2S ALSA Driver
  17  *      Copyright (c) by Phil Poole 2013
  18  *
  19  *      MARVELL MMP Peripheral DMA Driver
  20  *      Copyright 2012 Marvell International Ltd.
  21  *
  22  * This program is free software; you can redistribute it and/or modify
  23  * it under the terms of the GNU General Public License as published by
  24  * the Free Software Foundation; either version 2 of the License, or
  25  * (at your option) any later version.
  26  *
  27  * This program is distributed in the hope that it will be useful,
  28  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  29  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30  * GNU General Public License for more details.
  31  */
  32 #include <linux/dmaengine.h>
  33 #include <linux/dma-mapping.h>
  34 #include <linux/err.h>
  35 #include <linux/init.h>
  36 #include <linux/interrupt.h>
  37 #include <linux/list.h>
  38 #include <linux/module.h>
  39 #include <linux/platform_device.h>
  40 #include <linux/slab.h>
  41 #include <linux/io.h>
  42 #include <linux/spinlock.h>
  43 #include <linux/of.h>
  44 #include <linux/of_dma.h>
  45
  46 #include "virt-dma.h"
  47
  48 struct bcm2835_dmadev {
  49         struct dma_device ddev;
  50         spinlock_t lock;
  51         void __iomem *base;
  52         struct device_dma_parameters dma_parms;
  53 };
  54
  55 struct bcm2835_dma_cb {
  56         uint32_t info;
  57         uint32_t src;
  58         uint32_t dst;
  59         uint32_t length;
  60         uint32_t stride;
  61         uint32_t next;
  62         uint32_t pad[2];
  63 };
  64
  65 struct bcm2835_chan {
  66         struct virt_dma_chan vc;
  67         struct list_head node;
  68
  69         struct dma_slave_config cfg;
  70         bool cyclic;
  71         unsigned int dreq;
  72
  73         int ch;
  74         struct bcm2835_desc *desc;
  75
  76         void __iomem *chan_base;
  77         int irq_number;
  78 };
  79
  80 struct bcm2835_desc {
  81         struct virt_dma_desc vd;
  82         enum dma_transfer_direction dir;
  83
  84         unsigned int control_block_size;
  85         struct bcm2835_dma_cb *control_block_base;
  86         dma_addr_t control_block_base_phys;
  87
  88         unsigned int frames;
  89         size_t size;
  90 };
  91
  92 #define BCM2835_DMA_CS          0x00
  93 #define BCM2835_DMA_ADDR        0x04
  94 #define BCM2835_DMA_SOURCE_AD   0x0c
  95 #define BCM2835_DMA_DEST_AD     0x10
  96 #define BCM2835_DMA_NEXTCB      0x1C
  97
  98 /* DMA CS Control and Status bits */
  99 #define BCM2835_DMA_ACTIVE      BIT(0)
 100 #define BCM2835_DMA_INT BIT(2)
 101 #define BCM2835_DMA_ISPAUSED    BIT(4)  /* Pause requested or not active */
 102 #define BCM2835_DMA_ISHELD      BIT(5)  /* Is held by DREQ flow control */
 103 #define BCM2835_DMA_ERR BIT(8)
 104 #define BCM2835_DMA_ABORT       BIT(30) /* Stop current CB, go to next, WO */
 105 #define BCM2835_DMA_RESET       BIT(31) /* WO, self clearing */
 106
 107 #define BCM2835_DMA_INT_EN      BIT(0)
 108 #define BCM2835_DMA_D_INC       BIT(4)
 109 #define BCM2835_DMA_D_DREQ      BIT(6)
 110 #define BCM2835_DMA_S_INC       BIT(8)
 111 #define BCM2835_DMA_S_DREQ      BIT(10)
 112
 113 #define BCM2835_DMA_PER_MAP(x)  ((x) << 16)
 114
 115 #define BCM2835_DMA_DATA_TYPE_S8        1
 116 #define BCM2835_DMA_DATA_TYPE_S16       2
 117 #define BCM2835_DMA_DATA_TYPE_S32       4
 118 #define BCM2835_DMA_DATA_TYPE_S128      16
 119
 120 #define BCM2835_DMA_BULK_MASK   BIT(0)
 121 #define BCM2835_DMA_FIQ_MASK    (BIT(2) | BIT(3))
 122
 123 /* Valid only for channels 0 - 14, 15 has its own base address */
 124 #define BCM2835_DMA_CHAN(n)     ((n) << 8) /* Base address */
 125 #define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n))
 126
 127 static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
 128 {
 129         return container_of(d, struct bcm2835_dmadev, ddev);
 130 }
 131
 132 static inline struct bcm2835_chan *to_bcm2835_dma_chan(struct dma_chan *c)
 133 {
 134         return container_of(c, struct bcm2835_chan, vc.chan);
 135 }
 136
 137 static inline struct bcm2835_desc *to_bcm2835_dma_desc(
 138                 struct dma_async_tx_descriptor *t)
 139 {
 140         return container_of(t, struct bcm2835_desc, vd.tx);
 141 }
 142
 143 static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
 144 {
 145         struct bcm2835_desc *desc = container_of(vd, struct bcm2835_desc, vd);
 146         dma_free_coherent(desc->vd.tx.chan->device->dev,
 147                         desc->control_block_size,
 148                         desc->control_block_base,
 149                         desc->control_block_base_phys);
 150         kfree(desc);
 151 }
 152
 153 static int bcm2835_dma_abort(void __iomem *chan_base)
 154 {
 155         unsigned long cs;
 156         long int timeout = 10000;
 157
 158         cs = readl(chan_base + BCM2835_DMA_CS);
 159         if (!(cs & BCM2835_DMA_ACTIVE))
 160                 return 0;
 161
 162         /* Write 0 to the active bit - Pause the DMA */
 163         writel(0, chan_base + BCM2835_DMA_CS);
 164
 165         /* Wait for any current AXI transfer to complete */
 166         while ((cs & BCM2835_DMA_ISPAUSED) && --timeout) {
 167                 cpu_relax();
 168                 cs = readl(chan_base + BCM2835_DMA_CS);
 169         }
 170
 171         /* We'll un-pause when we set of our next DMA */
 172         if (!timeout)
 173                 return -ETIMEDOUT;
 174
 175         if (!(cs & BCM2835_DMA_ACTIVE))
 176                 return 0;
 177
 178         /* Terminate the control block chain */
 179         writel(0, chan_base + BCM2835_DMA_NEXTCB);
 180
 181         /* Abort the whole DMA */
 182         writel(BCM2835_DMA_ABORT | BCM2835_DMA_ACTIVE,
 183                chan_base + BCM2835_DMA_CS);
 184
 185         return 0;
 186 }
 187
 188 static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
 189 {
 190         struct virt_dma_desc *vd = vchan_next_desc(&c->vc);
 191         struct bcm2835_desc *d;
 192
 193         if (!vd) {
 194                 c->desc = NULL;
 195                 return;
 196         }
 197
 198         list_del(&vd->node);
 199
 200         c->desc = d = to_bcm2835_dma_desc(&vd->tx);
 201
 202         writel(d->control_block_base_phys, c->chan_base + BCM2835_DMA_ADDR);
 203         writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
 204 }
 205
 206 static irqreturn_t bcm2835_dma_callback(int irq, void *data)
 207 {
 208         struct bcm2835_chan *c = data;
 209         struct bcm2835_desc *d;
 210         unsigned long flags;
 211
 212         spin_lock_irqsave(&c->vc.lock, flags);
 213
 214         /* Acknowledge interrupt */
 215         writel(BCM2835_DMA_INT, c->chan_base + BCM2835_DMA_CS);
 216
 217         d = c->desc;
 218
 219         if (d) {
 220                 /* TODO Only works for cyclic DMA */
 221                 vchan_cyclic_callback(&d->vd);
 222         }
 223
 224         /* Keep the DMA engine running */
 225         writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
 226
 227         spin_unlock_irqrestore(&c->vc.lock, flags);
 228
 229         return IRQ_HANDLED;
 230 }
 231
 232 static int bcm2835_dma_alloc_chan_resources(struct dma_chan *chan)
 233 {
 234         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 235
 236         dev_dbg(c->vc.chan.device->dev,
 237                         "Allocating DMA channel %d\n", c->ch);
 238
 239         return request_irq(c->irq_number,
 240                         bcm2835_dma_callback, 0, "DMA IRQ", c);
 241 }
 242
 243 static void bcm2835_dma_free_chan_resources(struct dma_chan *chan)
 244 {
 245         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 246
 247         vchan_free_chan_resources(&c->vc);
 248         free_irq(c->irq_number, c);
 249
 250         dev_dbg(c->vc.chan.device->dev, "Freeing DMA channel %u\n", c->ch);
 251 }
 252
 253 static size_t bcm2835_dma_desc_size(struct bcm2835_desc *d)
 254 {
 255         return d->size;
 256 }
 257
 258 static size_t bcm2835_dma_desc_size_pos(struct bcm2835_desc *d, dma_addr_t addr)
 259 {
 260         unsigned int i;
 261         size_t size;
 262
 263         for (size = i = 0; i < d->frames; i++) {
 264                 struct bcm2835_dma_cb *control_block =
 265                         &d->control_block_base[i];
 266                 size_t this_size = control_block->length;
 267                 dma_addr_t dma;
 268
 269                 if (d->dir == DMA_DEV_TO_MEM)
 270                         dma = control_block->dst;
 271                 else
 272                         dma = control_block->src;
 273
 274                 if (size)
 275                         size += this_size;
 276                 else if (addr >= dma && addr < dma + this_size)
 277                         size += dma + this_size - addr;
 278         }
 279
 280         return size;
 281 }
 282
 283 static enum dma_status bcm2835_dma_tx_status(struct dma_chan *chan,
 284         dma_cookie_t cookie, struct dma_tx_state *txstate)
 285 {
 286         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 287         struct virt_dma_desc *vd;
 288         enum dma_status ret;
 289         unsigned long flags;
 290
 291         ret = dma_cookie_status(chan, cookie, txstate);
 292         if (ret == DMA_COMPLETE || !txstate)
 293                 return ret;
 294
 295         spin_lock_irqsave(&c->vc.lock, flags);
 296         vd = vchan_find_desc(&c->vc, cookie);
 297         if (vd) {
 298                 txstate->residue =
 299                         bcm2835_dma_desc_size(to_bcm2835_dma_desc(&vd->tx));
 300         } else if (c->desc && c->desc->vd.tx.cookie == cookie) {
 301                 struct bcm2835_desc *d = c->desc;
 302                 dma_addr_t pos;
 303
 304                 if (d->dir == DMA_MEM_TO_DEV)
 305                         pos = readl(c->chan_base + BCM2835_DMA_SOURCE_AD);
 306                 else if (d->dir == DMA_DEV_TO_MEM)
 307                         pos = readl(c->chan_base + BCM2835_DMA_DEST_AD);
 308                 else
 309                         pos = 0;
 310
 311                 txstate->residue = bcm2835_dma_desc_size_pos(d, pos);
 312         } else {
 313                 txstate->residue = 0;
 314         }
 315
 316         spin_unlock_irqrestore(&c->vc.lock, flags);
 317
 318         return ret;
 319 }
 320
 321 static void bcm2835_dma_issue_pending(struct dma_chan *chan)
 322 {
 323         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 324         unsigned long flags;
 325
 326         c->cyclic = true; /* Nothing else is implemented */
 327
 328         spin_lock_irqsave(&c->vc.lock, flags);
 329         if (vchan_issue_pending(&c->vc) && !c->desc)
 330                 bcm2835_dma_start_desc(c);
 331
 332         spin_unlock_irqrestore(&c->vc.lock, flags);
 333 }
 334
 335 static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 336         struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
 337         size_t period_len, enum dma_transfer_direction direction,
 338         unsigned long flags)
 339 {
 340         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 341         enum dma_slave_buswidth dev_width;
 342         struct bcm2835_desc *d;
 343         dma_addr_t dev_addr;
 344         unsigned int es, sync_type;
 345         unsigned int frame;
 346
 347         /* Grab configuration */
 348         if (!is_slave_direction(direction)) {
 349                 dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
 350                 return NULL;
 351         }
 352
 353         if (direction == DMA_DEV_TO_MEM) {
 354                 dev_addr = c->cfg.src_addr;
 355                 dev_width = c->cfg.src_addr_width;
 356                 sync_type = BCM2835_DMA_S_DREQ;
 357         } else {
 358                 dev_addr = c->cfg.dst_addr;
 359                 dev_width = c->cfg.dst_addr_width;
 360                 sync_type = BCM2835_DMA_D_DREQ;
 361         }
 362
 363         /* Bus width translates to the element size (ES) */
 364         switch (dev_width) {
 365         case DMA_SLAVE_BUSWIDTH_4_BYTES:
 366                 es = BCM2835_DMA_DATA_TYPE_S32;
 367                 break;
 368         default:
 369                 return NULL;
 370         }
 371
 372         /* Now allocate and setup the descriptor. */
 373         d = kzalloc(sizeof(*d), GFP_NOWAIT);
 374         if (!d)
 375                 return NULL;
 376
 377         d->dir = direction;
 378         d->frames = buf_len / period_len;
 379
 380         /* Allocate memory for control blocks */
 381         d->control_block_size = d->frames * sizeof(struct bcm2835_dma_cb);
 382         d->control_block_base = dma_zalloc_coherent(chan->device->dev,
 383                         d->control_block_size, &d->control_block_base_phys,
 384                         GFP_NOWAIT);
 385
 386         if (!d->control_block_base) {
 387                 kfree(d);
 388                 return NULL;
 389         }
 390
 391         /*
 392          * Iterate over all frames, create a control block
 393          * for each frame and link them together.
 394          */
 395         for (frame = 0; frame < d->frames; frame++) {
 396                 struct bcm2835_dma_cb *control_block =
 397                         &d->control_block_base[frame];
 398
 399                 /* Setup adresses */
 400                 if (d->dir == DMA_DEV_TO_MEM) {
 401                         control_block->info = BCM2835_DMA_D_INC;
 402                         control_block->src = dev_addr;
 403                         control_block->dst = buf_addr + frame * period_len;
 404                 } else {
 405                         control_block->info = BCM2835_DMA_S_INC;
 406                         control_block->src = buf_addr + frame * period_len;
 407                         control_block->dst = dev_addr;
 408                 }
 409
 410                 /* Enable interrupt */
 411                 control_block->info |= BCM2835_DMA_INT_EN;
 412
 413                 /* Setup synchronization */
 414                 if (sync_type != 0)
 415                         control_block->info |= sync_type;
 416
 417                 /* Setup DREQ channel */
 418                 if (c->dreq != 0)
 419                         control_block->info |=
 420                                 BCM2835_DMA_PER_MAP(c->dreq);
 421
 422                 /* Length of a frame */
 423                 control_block->length = period_len;
 424                 d->size += control_block->length;
 425
 426                 /*
 427                  * Next block is the next frame.
 428                  * This DMA engine driver currently only supports cyclic DMA.
 429                  * Therefore, wrap around at number of frames.
 430                  */
 431                 control_block->next = d->control_block_base_phys +
 432                         sizeof(struct bcm2835_dma_cb)
 433                         * ((frame + 1) % d->frames);
 434         }
 435
 436         return vchan_tx_prep(&c->vc, &d->vd, flags);
 437 }
 438
 439 static int bcm2835_dma_slave_config(struct bcm2835_chan *c,
 440                 struct dma_slave_config *cfg)
 441 {
 442         if ((cfg->direction == DMA_DEV_TO_MEM &&
 443              cfg->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) ||
 444             (cfg->direction == DMA_MEM_TO_DEV &&
 445              cfg->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) ||
 446             !is_slave_direction(cfg->direction)) {
 447                 return -EINVAL;
 448         }
 449
 450         c->cfg = *cfg;
 451
 452         return 0;
 453 }
 454
 455 static int bcm2835_dma_terminate_all(struct bcm2835_chan *c)
 456 {
 457         struct bcm2835_dmadev *d = to_bcm2835_dma_dev(c->vc.chan.device);
 458         unsigned long flags;
 459         int timeout = 10000;
 460         LIST_HEAD(head);
 461
 462         spin_lock_irqsave(&c->vc.lock, flags);
 463
 464         /* Prevent this channel being scheduled */
 465         spin_lock(&d->lock);
 466         list_del_init(&c->node);
 467         spin_unlock(&d->lock);
 468
 469         /*
 470          * Stop DMA activity: we assume the callback will not be called
 471          * after bcm_dma_abort() returns (even if it does, it will see
 472          * c->desc is NULL and exit.)
 473          */
 474         if (c->desc) {
 475                 c->desc = NULL;
 476                 bcm2835_dma_abort(c->chan_base);
 477
 478                 /* Wait for stopping */
 479                 while (--timeout) {
 480                         if (!(readl(c->chan_base + BCM2835_DMA_CS) &
 481                                                 BCM2835_DMA_ACTIVE))
 482                                 break;
 483
 484                         cpu_relax();
 485                 }
 486
 487                 if (!timeout)
 488                         dev_err(d->ddev.dev, "DMA transfer could not be terminated\n");
 489         }
 490
 491         vchan_get_all_descriptors(&c->vc, &head);
 492         spin_unlock_irqrestore(&c->vc.lock, flags);
 493         vchan_dma_desc_free_list(&c->vc, &head);
 494
 495         return 0;
 496 }
 497
 498 static int bcm2835_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
 499         unsigned long arg)
 500 {
 501         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 502
 503         switch (cmd) {
 504         case DMA_SLAVE_CONFIG:
 505                 return bcm2835_dma_slave_config(c,
 506                                 (struct dma_slave_config *)arg);
 507
 508         case DMA_TERMINATE_ALL:
 509                 return bcm2835_dma_terminate_all(c);
 510
 511         default:
 512                 return -ENXIO;
 513         }
 514 }
 515
 516 static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id, int irq)
 517 {
 518         struct bcm2835_chan *c;
 519
 520         c = devm_kzalloc(d->ddev.dev, sizeof(*c), GFP_KERNEL);
 521         if (!c)
 522                 return -ENOMEM;
 523
 524         c->vc.desc_free = bcm2835_dma_desc_free;
 525         vchan_init(&c->vc, &d->ddev);
 526         INIT_LIST_HEAD(&c->node);
 527
 528         d->ddev.chancnt++;
 529
 530         c->chan_base = BCM2835_DMA_CHANIO(d->base, chan_id);
 531         c->ch = chan_id;
 532         c->irq_number = irq;
 533
 534         return 0;
 535 }
 536
 537 static void bcm2835_dma_free(struct bcm2835_dmadev *od)
 538 {
 539         struct bcm2835_chan *c, *next;
 540
 541         list_for_each_entry_safe(c, next, &od->ddev.channels,
 542                                  vc.chan.device_node) {
 543                 list_del(&c->vc.chan.device_node);
 544                 tasklet_kill(&c->vc.task);
 545         }
 546 }
 547
 548 static const struct of_device_id bcm2835_dma_of_match[] = {
 549         { .compatible = "brcm,bcm2835-dma", },
 550         {},
 551 };
 552 MODULE_DEVICE_TABLE(of, bcm2835_dma_of_match);
 553
 554 static struct dma_chan *bcm2835_dma_xlate(struct of_phandle_args *spec,
 555                                            struct of_dma *ofdma)
 556 {
 557         struct bcm2835_dmadev *d = ofdma->of_dma_data;
 558         struct dma_chan *chan;
 559
 560         chan = dma_get_any_slave_channel(&d->ddev);
 561         if (!chan)
 562                 return NULL;
 563
 564         /* Set DREQ from param */
 565         to_bcm2835_dma_chan(chan)->dreq = spec->args[0];
 566
 567         return chan;
 568 }
 569
 570 static int bcm2835_dma_device_slave_caps(struct dma_chan *dchan,
 571         struct dma_slave_caps *caps)
 572 {
 573         caps->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
 574         caps->dstn_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
 575         caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
 576         caps->cmd_pause = false;
 577         caps->cmd_terminate = true;
 578
 579         return 0;
 580 }
 581
 582 static int bcm2835_dma_probe(struct platform_device *pdev)
 583 {
 584         struct bcm2835_dmadev *od;
 585         struct resource *res;
 586         void __iomem *base;
 587         int rc;
 588         int i;
 589         int irq;
 590         uint32_t chans_available;
 591
 592         if (!pdev->dev.dma_mask)
 593                 pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
 594
 595         rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
 596         if (rc)
 597                 return rc;
 598
 599         od = devm_kzalloc(&pdev->dev, sizeof(*od), GFP_KERNEL);
 600         if (!od)
 601                 return -ENOMEM;
 602
 603         pdev->dev.dma_parms = &od->dma_parms;
 604         dma_set_max_seg_size(&pdev->dev, 0x3FFFFFFF);
 605
 606         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 607         base = devm_ioremap_resource(&pdev->dev, res);
 608         if (IS_ERR(base))
 609                 return PTR_ERR(base);
 610
 611         od->base = base;
 612
 613         dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
 614         dma_cap_set(DMA_PRIVATE, od->ddev.cap_mask);
 615         dma_cap_set(DMA_CYCLIC, od->ddev.cap_mask);
 616         od->ddev.device_alloc_chan_resources = bcm2835_dma_alloc_chan_resources;
 617         od->ddev.device_free_chan_resources = bcm2835_dma_free_chan_resources;
 618         od->ddev.device_tx_status = bcm2835_dma_tx_status;
 619         od->ddev.device_issue_pending = bcm2835_dma_issue_pending;
 620         od->ddev.device_slave_caps = bcm2835_dma_device_slave_caps;
 621         od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic;
 622         od->ddev.device_control = bcm2835_dma_control;
 623         od->ddev.dev = &pdev->dev;
 624         INIT_LIST_HEAD(&od->ddev.channels);
 625         spin_lock_init(&od->lock);
 626
 627         platform_set_drvdata(pdev, od);
 628
 629         /* Request DMA channel mask from device tree */
 630         if (of_property_read_u32(pdev->dev.of_node,
 631                         "brcm,dma-channel-mask",
 632                         &chans_available)) {
 633                 dev_err(&pdev->dev, "Failed to get channel mask\n");
 634                 rc = -EINVAL;
 635                 goto err_no_dma;
 636         }
 637
 638         /*
 639          * Do not use the FIQ and BULK channels,
 640          * because they are used by the GPU.
 641          */
 642         chans_available &= ~(BCM2835_DMA_FIQ_MASK | BCM2835_DMA_BULK_MASK);
 643
 644         for (i = 0; i < pdev->num_resources; i++) {
 645                 irq = platform_get_irq(pdev, i);
 646                 if (irq < 0)
 647                         break;
 648
 649                 if (chans_available & (1 << i)) {
 650                         rc = bcm2835_dma_chan_init(od, i, irq);
 651                         if (rc)
 652                                 goto err_no_dma;
 653                 }
 654         }
 655
 656         dev_dbg(&pdev->dev, "Initialized %i DMA channels\n", i);
 657
 658         /* Device-tree DMA controller registration */
 659         rc = of_dma_controller_register(pdev->dev.of_node,
 660                         bcm2835_dma_xlate, od);
 661         if (rc) {
 662                 dev_err(&pdev->dev, "Failed to register DMA controller\n");
 663                 goto err_no_dma;
 664         }
 665
 666         rc = dma_async_device_register(&od->ddev);
 667         if (rc) {
 668                 dev_err(&pdev->dev,
 669                         "Failed to register slave DMA engine device: %d\n", rc);
 670                 goto err_no_dma;
 671         }
 672
 673         dev_dbg(&pdev->dev, "Load BCM2835 DMA engine driver\n");
 674
 675         return 0;
 676
 677 err_no_dma:
 678         bcm2835_dma_free(od);
 679         return rc;
 680 }
 681
 682 static int bcm2835_dma_remove(struct platform_device *pdev)
 683 {
 684         struct bcm2835_dmadev *od = platform_get_drvdata(pdev);
 685
 686         dma_async_device_unregister(&od->ddev);
 687         bcm2835_dma_free(od);
 688
 689         return 0;
 690 }
 691
 692 static struct platform_driver bcm2835_dma_driver = {
 693         .probe  = bcm2835_dma_probe,
 694         .remove = bcm2835_dma_remove,
 695         .driver = {
 696                 .name = "bcm2835-dma",
 697                 .owner = THIS_MODULE,
 698                 .of_match_table = of_match_ptr(bcm2835_dma_of_match),
 699         },
 700 };
 701
 702 module_platform_driver(bcm2835_dma_driver);
 703
 704 MODULE_ALIAS("platform:bcm2835-dma");
 705 MODULE_DESCRIPTION("BCM2835 DMA engine driver");
 706 MODULE_AUTHOR("Florian Meier <florian.meier@koalo.de>");
 707 MODULE_LICENSE("GPL v2");