drivers/amba/bus.c

   1 /*
   2  *  linux/arch/arm/common/amba.c
   3  *
   4  *  Copyright (C) 2003 Deep Blue Solutions Ltd, All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/device.h>
  13 #include <linux/string.h>
  14 #include <linux/slab.h>
  15 #include <linux/io.h>
  16 #include <linux/pm.h>
  17 #include <linux/pm_runtime.h>
  18 #include <linux/amba/bus.h>
  19
  20 #include <asm/irq.h>
  21 #include <asm/sizes.h>
  22
  23 #define to_amba_driver(d)       container_of(d, struct amba_driver, drv)
  24
  25 static const struct amba_id *
  26 amba_lookup(const struct amba_id *table, struct amba_device *dev)
  27 {
  28         int ret = 0;
  29
  30         while (table->mask) {
  31                 ret = (dev->periphid & table->mask) == table->id;
  32                 if (ret)
  33                         break;
  34                 table++;
  35         }
  36
  37         return ret ? table : NULL;
  38 }
  39
  40 static int amba_match(struct device *dev, struct device_driver *drv)
  41 {
  42         struct amba_device *pcdev = to_amba_device(dev);
  43         struct amba_driver *pcdrv = to_amba_driver(drv);
  44
  45         return amba_lookup(pcdrv->id_table, pcdev) != NULL;
  46 }
  47
  48 #ifdef CONFIG_HOTPLUG
  49 static int amba_uevent(struct device *dev, struct kobj_uevent_env *env)
  50 {
  51         struct amba_device *pcdev = to_amba_device(dev);
  52         int retval = 0;
  53
  54         retval = add_uevent_var(env, "AMBA_ID=%08x", pcdev->periphid);
  55         return retval;
  56 }
  57 #else
  58 #define amba_uevent NULL
  59 #endif
  60
  61 #define amba_attr_func(name,fmt,arg...)                                 \
  62 static ssize_t name##_show(struct device *_dev,                         \
  63                            struct device_attribute *attr, char *buf)    \
  64 {                                                                       \
  65         struct amba_device *dev = to_amba_device(_dev);                 \
  66         return sprintf(buf, fmt, arg);                                  \
  67 }
  68
  69 #define amba_attr(name,fmt,arg...)      \
  70 amba_attr_func(name,fmt,arg)            \
  71 static DEVICE_ATTR(name, S_IRUGO, name##_show, NULL)
  72
  73 amba_attr_func(id, "%08x\n", dev->periphid);
  74 amba_attr(irq0, "%u\n", dev->irq[0]);
  75 amba_attr(irq1, "%u\n", dev->irq[1]);
  76 amba_attr_func(resource, "\t%016llx\t%016llx\t%016lx\n",
  77          (unsigned long long)dev->res.start, (unsigned long long)dev->res.end,
  78          dev->res.flags);
  79
  80 static struct device_attribute amba_dev_attrs[] = {
  81         __ATTR_RO(id),
  82         __ATTR_RO(resource),
  83         __ATTR_NULL,
  84 };
  85
  86 #ifdef CONFIG_PM_SLEEP
  87
  88 static int amba_legacy_suspend(struct device *dev, pm_message_t mesg)
  89 {
  90         struct amba_driver *adrv = to_amba_driver(dev->driver);
  91         struct amba_device *adev = to_amba_device(dev);
  92         int ret = 0;
  93
  94         if (dev->driver && adrv->suspend)
  95                 ret = adrv->suspend(adev, mesg);
  96
  97         return ret;
  98 }
  99
 100 static int amba_legacy_resume(struct device *dev)
 101 {
 102         struct amba_driver *adrv = to_amba_driver(dev->driver);
 103         struct amba_device *adev = to_amba_device(dev);
 104         int ret = 0;
 105
 106         if (dev->driver && adrv->resume)
 107                 ret = adrv->resume(adev);
 108
 109         return ret;
 110 }
 111
 112 static int amba_pm_prepare(struct device *dev)
 113 {
 114         struct device_driver *drv = dev->driver;
 115         int ret = 0;
 116
 117         if (drv && drv->pm && drv->pm->prepare)
 118                 ret = drv->pm->prepare(dev);
 119
 120         return ret;
 121 }
 122
 123 static void amba_pm_complete(struct device *dev)
 124 {
 125         struct device_driver *drv = dev->driver;
 126
 127         if (drv && drv->pm && drv->pm->complete)
 128                 drv->pm->complete(dev);
 129 }
 130
 131 #else /* !CONFIG_PM_SLEEP */
 132
 133 #define amba_pm_prepare         NULL
 134 #define amba_pm_complete                NULL
 135
 136 #endif /* !CONFIG_PM_SLEEP */
 137
 138 #ifdef CONFIG_SUSPEND
 139
 140 static int amba_pm_suspend(struct device *dev)
 141 {
 142         struct device_driver *drv = dev->driver;
 143         int ret = 0;
 144
 145         if (!drv)
 146                 return 0;
 147
 148         if (drv->pm) {
 149                 if (drv->pm->suspend)
 150                         ret = drv->pm->suspend(dev);
 151         } else {
 152                 ret = amba_legacy_suspend(dev, PMSG_SUSPEND);
 153         }
 154
 155         return ret;
 156 }
 157
 158 static int amba_pm_suspend_noirq(struct device *dev)
 159 {
 160         struct device_driver *drv = dev->driver;
 161         int ret = 0;
 162
 163         if (!drv)
 164                 return 0;
 165
 166         if (drv->pm) {
 167                 if (drv->pm->suspend_noirq)
 168                         ret = drv->pm->suspend_noirq(dev);
 169         }
 170
 171         return ret;
 172 }
 173
 174 static int amba_pm_resume(struct device *dev)
 175 {
 176         struct device_driver *drv = dev->driver;
 177         int ret = 0;
 178
 179         if (!drv)
 180                 return 0;
 181
 182         if (drv->pm) {
 183                 if (drv->pm->resume)
 184                         ret = drv->pm->resume(dev);
 185         } else {
 186                 ret = amba_legacy_resume(dev);
 187         }
 188
 189         return ret;
 190 }
 191
 192 static int amba_pm_resume_noirq(struct device *dev)
 193 {
 194         struct device_driver *drv = dev->driver;
 195         int ret = 0;
 196
 197         if (!drv)
 198                 return 0;
 199
 200         if (drv->pm) {
 201                 if (drv->pm->resume_noirq)
 202                         ret = drv->pm->resume_noirq(dev);
 203         }
 204
 205         return ret;
 206 }
 207
 208 #else /* !CONFIG_SUSPEND */
 209
 210 #define amba_pm_suspend         NULL
 211 #define amba_pm_resume          NULL
 212 #define amba_pm_suspend_noirq   NULL
 213 #define amba_pm_resume_noirq    NULL
 214
 215 #endif /* !CONFIG_SUSPEND */
 216
 217 #ifdef CONFIG_HIBERNATE_CALLBACKS
 218
 219 static int amba_pm_freeze(struct device *dev)
 220 {
 221         struct device_driver *drv = dev->driver;
 222         int ret = 0;
 223
 224         if (!drv)
 225                 return 0;
 226
 227         if (drv->pm) {
 228                 if (drv->pm->freeze)
 229                         ret = drv->pm->freeze(dev);
 230         } else {
 231                 ret = amba_legacy_suspend(dev, PMSG_FREEZE);
 232         }
 233
 234         return ret;
 235 }
 236
 237 static int amba_pm_freeze_noirq(struct device *dev)
 238 {
 239         struct device_driver *drv = dev->driver;
 240         int ret = 0;
 241
 242         if (!drv)
 243                 return 0;
 244
 245         if (drv->pm) {
 246                 if (drv->pm->freeze_noirq)
 247                         ret = drv->pm->freeze_noirq(dev);
 248         }
 249
 250         return ret;
 251 }
 252
 253 static int amba_pm_thaw(struct device *dev)
 254 {
 255         struct device_driver *drv = dev->driver;
 256         int ret = 0;
 257
 258         if (!drv)
 259                 return 0;
 260
 261         if (drv->pm) {
 262                 if (drv->pm->thaw)
 263                         ret = drv->pm->thaw(dev);
 264         } else {
 265                 ret = amba_legacy_resume(dev);
 266         }
 267
 268         return ret;
 269 }
 270
 271 static int amba_pm_thaw_noirq(struct device *dev)
 272 {
 273         struct device_driver *drv = dev->driver;
 274         int ret = 0;
 275
 276         if (!drv)
 277                 return 0;
 278
 279         if (drv->pm) {
 280                 if (drv->pm->thaw_noirq)
 281                         ret = drv->pm->thaw_noirq(dev);
 282         }
 283
 284         return ret;
 285 }
 286
 287 static int amba_pm_poweroff(struct device *dev)
 288 {
 289         struct device_driver *drv = dev->driver;
 290         int ret = 0;
 291
 292         if (!drv)
 293                 return 0;
 294
 295         if (drv->pm) {
 296                 if (drv->pm->poweroff)
 297                         ret = drv->pm->poweroff(dev);
 298         } else {
 299                 ret = amba_legacy_suspend(dev, PMSG_HIBERNATE);
 300         }
 301
 302         return ret;
 303 }
 304
 305 static int amba_pm_poweroff_noirq(struct device *dev)
 306 {
 307         struct device_driver *drv = dev->driver;
 308         int ret = 0;
 309
 310         if (!drv)
 311                 return 0;
 312
 313         if (drv->pm) {
 314                 if (drv->pm->poweroff_noirq)
 315                         ret = drv->pm->poweroff_noirq(dev);
 316         }
 317
 318         return ret;
 319 }
 320
 321 static int amba_pm_restore(struct device *dev)
 322 {
 323         struct device_driver *drv = dev->driver;
 324         int ret = 0;
 325
 326         if (!drv)
 327                 return 0;
 328
 329         if (drv->pm) {
 330                 if (drv->pm->restore)
 331                         ret = drv->pm->restore(dev);
 332         } else {
 333                 ret = amba_legacy_resume(dev);
 334         }
 335
 336         return ret;
 337 }
 338
 339 static int amba_pm_restore_noirq(struct device *dev)
 340 {
 341         struct device_driver *drv = dev->driver;
 342         int ret = 0;
 343
 344         if (!drv)
 345                 return 0;
 346
 347         if (drv->pm) {
 348                 if (drv->pm->restore_noirq)
 349                         ret = drv->pm->restore_noirq(dev);
 350         }
 351
 352         return ret;
 353 }
 354
 355 #else /* !CONFIG_HIBERNATE_CALLBACKS */
 356
 357 #define amba_pm_freeze          NULL
 358 #define amba_pm_thaw            NULL
 359 #define amba_pm_poweroff                NULL
 360 #define amba_pm_restore         NULL
 361 #define amba_pm_freeze_noirq    NULL
 362 #define amba_pm_thaw_noirq              NULL
 363 #define amba_pm_poweroff_noirq  NULL
 364 #define amba_pm_restore_noirq   NULL
 365
 366 #endif /* !CONFIG_HIBERNATE_CALLBACKS */
 367
 368 #ifdef CONFIG_PM_RUNTIME
 369 /*
 370  * Hooks to provide runtime PM of the pclk (bus clock).  It is safe to
 371  * enable/disable the bus clock at runtime PM suspend/resume as this
 372  * does not result in loss of context.  However, disabling vcore power
 373  * would do, so we leave that to the driver.
 374  */
 375 static int amba_pm_runtime_suspend(struct device *dev)
 376 {
 377         struct amba_device *pcdev = to_amba_device(dev);
 378         int ret = pm_generic_runtime_suspend(dev);
 379
 380         if (ret == 0 && dev->driver)
 381                 clk_disable(pcdev->pclk);
 382
 383         return ret;
 384 }
 385
 386 static int amba_pm_runtime_resume(struct device *dev)
 387 {
 388         struct amba_device *pcdev = to_amba_device(dev);
 389         int ret;
 390
 391         if (dev->driver) {
 392                 ret = clk_enable(pcdev->pclk);
 393                 /* Failure is probably fatal to the system, but... */
 394                 if (ret)
 395                         return ret;
 396         }
 397
 398         return pm_generic_runtime_resume(dev);
 399 }
 400 #endif
 401
 402 #ifdef CONFIG_PM
 403
 404 static const struct dev_pm_ops amba_pm = {
 405         .prepare        = amba_pm_prepare,
 406         .complete       = amba_pm_complete,
 407         .suspend        = amba_pm_suspend,
 408         .resume         = amba_pm_resume,
 409         .freeze         = amba_pm_freeze,
 410         .thaw           = amba_pm_thaw,
 411         .poweroff       = amba_pm_poweroff,
 412         .restore        = amba_pm_restore,
 413         .suspend_noirq  = amba_pm_suspend_noirq,
 414         .resume_noirq   = amba_pm_resume_noirq,
 415         .freeze_noirq   = amba_pm_freeze_noirq,
 416         .thaw_noirq     = amba_pm_thaw_noirq,
 417         .poweroff_noirq = amba_pm_poweroff_noirq,
 418         .restore_noirq  = amba_pm_restore_noirq,
 419         SET_RUNTIME_PM_OPS(
 420                 amba_pm_runtime_suspend,
 421                 amba_pm_runtime_resume,
 422                 pm_generic_runtime_idle
 423         )
 424 };
 425
 426 #define AMBA_PM (&amba_pm)
 427
 428 #else /* !CONFIG_PM */
 429
 430 #define AMBA_PM NULL
 431
 432 #endif /* !CONFIG_PM */
 433
 434 /*
 435  * Primecells are part of the Advanced Microcontroller Bus Architecture,
 436  * so we call the bus "amba".
 437  */
 438 struct bus_type amba_bustype = {
 439         .name           = "amba",
 440         .dev_attrs      = amba_dev_attrs,
 441         .match          = amba_match,
 442         .uevent         = amba_uevent,
 443         .pm             = AMBA_PM,
 444 };
 445
 446 static int __init amba_init(void)
 447 {
 448         return bus_register(&amba_bustype);
 449 }
 450
 451 postcore_initcall(amba_init);
 452
 453 static int amba_get_enable_pclk(struct amba_device *pcdev)
 454 {
 455         struct clk *pclk = clk_get(&pcdev->dev, "apb_pclk");
 456         int ret;
 457
 458         pcdev->pclk = pclk;
 459
 460         if (IS_ERR(pclk))
 461                 return PTR_ERR(pclk);
 462
 463         ret = clk_prepare(pclk);
 464         if (ret) {
 465                 clk_put(pclk);
 466                 return ret;
 467         }
 468
 469         ret = clk_enable(pclk);
 470         if (ret) {
 471                 clk_unprepare(pclk);
 472                 clk_put(pclk);
 473         }
 474
 475         return ret;
 476 }
 477
 478 static void amba_put_disable_pclk(struct amba_device *pcdev)
 479 {
 480         struct clk *pclk = pcdev->pclk;
 481
 482         clk_disable(pclk);
 483         clk_unprepare(pclk);
 484         clk_put(pclk);
 485 }
 486
 487 static int amba_get_enable_vcore(struct amba_device *pcdev)
 488 {
 489         struct regulator *vcore = regulator_get(&pcdev->dev, "vcore");
 490         int ret;
 491
 492         pcdev->vcore = vcore;
 493
 494         if (IS_ERR(vcore)) {
 495                 /* It is OK not to supply a vcore regulator */
 496                 if (PTR_ERR(vcore) == -ENODEV)
 497                         return 0;
 498                 return PTR_ERR(vcore);
 499         }
 500
 501         ret = regulator_enable(vcore);
 502         if (ret) {
 503                 regulator_put(vcore);
 504                 pcdev->vcore = ERR_PTR(-ENODEV);
 505         }
 506
 507         return ret;
 508 }
 509
 510 static void amba_put_disable_vcore(struct amba_device *pcdev)
 511 {
 512         struct regulator *vcore = pcdev->vcore;
 513
 514         if (!IS_ERR(vcore)) {
 515                 regulator_disable(vcore);
 516                 regulator_put(vcore);
 517         }
 518 }
 519
 520 /*
 521  * These are the device model conversion veneers; they convert the
 522  * device model structures to our more specific structures.
 523  */
 524 static int amba_probe(struct device *dev)
 525 {
 526         struct amba_device *pcdev = to_amba_device(dev);
 527         struct amba_driver *pcdrv = to_amba_driver(dev->driver);
 528         const struct amba_id *id = amba_lookup(pcdrv->id_table, pcdev);
 529         int ret;
 530
 531         do {
 532                 ret = amba_get_enable_vcore(pcdev);
 533                 if (ret)
 534                         break;
 535
 536                 ret = amba_get_enable_pclk(pcdev);
 537                 if (ret)
 538                         break;
 539
 540                 pm_runtime_get_noresume(dev);
 541                 pm_runtime_set_active(dev);
 542                 pm_runtime_enable(dev);
 543
 544                 ret = pcdrv->probe(pcdev, id);
 545                 if (ret == 0)
 546                         break;
 547
 548                 pm_runtime_disable(dev);
 549                 pm_runtime_set_suspended(dev);
 550                 pm_runtime_put_noidle(dev);
 551
 552                 amba_put_disable_pclk(pcdev);
 553                 amba_put_disable_vcore(pcdev);
 554         } while (0);
 555
 556         return ret;
 557 }
 558
 559 static int amba_remove(struct device *dev)
 560 {
 561         struct amba_device *pcdev = to_amba_device(dev);
 562         struct amba_driver *drv = to_amba_driver(dev->driver);
 563         int ret;
 564
 565         pm_runtime_get_sync(dev);
 566         ret = drv->remove(pcdev);
 567         pm_runtime_put_noidle(dev);
 568
 569         /* Undo the runtime PM settings in amba_probe() */
 570         pm_runtime_disable(dev);
 571         pm_runtime_set_suspended(dev);
 572         pm_runtime_put_noidle(dev);
 573
 574         amba_put_disable_pclk(pcdev);
 575         amba_put_disable_vcore(pcdev);
 576
 577         return ret;
 578 }
 579
 580 static void amba_shutdown(struct device *dev)
 581 {
 582         struct amba_driver *drv = to_amba_driver(dev->driver);
 583         drv->shutdown(to_amba_device(dev));
 584 }
 585
 586 /**
 587  *      amba_driver_register - register an AMBA device driver
 588  *      @drv: amba device driver structure
 589  *
 590  *      Register an AMBA device driver with the Linux device model
 591  *      core.  If devices pre-exist, the drivers probe function will
 592  *      be called.
 593  */
 594 int amba_driver_register(struct amba_driver *drv)
 595 {
 596         drv->drv.bus = &amba_bustype;
 597
 598 #define SETFN(fn)       if (drv->fn) drv->drv.fn = amba_##fn
 599         SETFN(probe);
 600         SETFN(remove);
 601         SETFN(shutdown);
 602
 603         return driver_register(&drv->drv);
 604 }
 605
 606 /**
 607  *      amba_driver_unregister - remove an AMBA device driver
 608  *      @drv: AMBA device driver structure to remove
 609  *
 610  *      Unregister an AMBA device driver from the Linux device
 611  *      model.  The device model will call the drivers remove function
 612  *      for each device the device driver is currently handling.
 613  */
 614 void amba_driver_unregister(struct amba_driver *drv)
 615 {
 616         driver_unregister(&drv->drv);
 617 }
 618
 619
 620 static void amba_device_release(struct device *dev)
 621 {
 622         struct amba_device *d = to_amba_device(dev);
 623
 624         if (d->res.parent)
 625                 release_resource(&d->res);
 626         kfree(d);
 627 }
 628
 629 /**
 630  *      amba_device_register - register an AMBA device
 631  *      @dev: AMBA device to register
 632  *      @parent: parent memory resource
 633  *
 634  *      Setup the AMBA device, reading the cell ID if present.
 635  *      Claim the resource, and register the AMBA device with
 636  *      the Linux device manager.
 637  */
 638 int amba_device_register(struct amba_device *dev, struct resource *parent)
 639 {
 640         u32 size;
 641         void __iomem *tmp;
 642         int i, ret;
 643
 644         device_initialize(&dev->dev);
 645
 646         /*
 647          * Copy from device_add
 648          */
 649         if (dev->dev.init_name) {
 650                 dev_set_name(&dev->dev, "%s", dev->dev.init_name);
 651                 dev->dev.init_name = NULL;
 652         }
 653
 654         dev->dev.release = amba_device_release;
 655         dev->dev.bus = &amba_bustype;
 656         dev->dev.dma_mask = &dev->dma_mask;
 657         dev->res.name = dev_name(&dev->dev);
 658
 659         if (!dev->dev.coherent_dma_mask && dev->dma_mask)
 660                 dev_warn(&dev->dev, "coherent dma mask is unset\n");
 661
 662         ret = request_resource(parent, &dev->res);
 663         if (ret)
 664                 goto err_out;
 665
 666         /* Hard-coded primecell ID instead of plug-n-play */
 667         if (dev->periphid != 0)
 668                 goto skip_probe;
 669
 670         /*
 671          * Dynamically calculate the size of the resource
 672          * and use this for iomap
 673          */
 674         size = resource_size(&dev->res);
 675         tmp = ioremap(dev->res.start, size);
 676         if (!tmp) {
 677                 ret = -ENOMEM;
 678                 goto err_release;
 679         }
 680
 681         ret = amba_get_enable_pclk(dev);
 682         if (ret == 0) {
 683                 u32 pid, cid;
 684
 685                 /*
 686                  * Read pid and cid based on size of resource
 687                  * they are located at end of region
 688                  */
 689                 for (pid = 0, i = 0; i < 4; i++)
 690                         pid |= (readl(tmp + size - 0x20 + 4 * i) & 255) <<
 691                                 (i * 8);
 692                 for (cid = 0, i = 0; i < 4; i++)
 693                         cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) <<
 694                                 (i * 8);
 695
 696                 amba_put_disable_pclk(dev);
 697
 698                 if (cid == AMBA_CID)
 699                         dev->periphid = pid;
 700
 701                 if (!dev->periphid)
 702                         ret = -ENODEV;
 703         }
 704
 705         iounmap(tmp);
 706
 707         if (ret)
 708                 goto err_release;
 709
 710  skip_probe:
 711         ret = device_add(&dev->dev);
 712         if (ret)
 713                 goto err_release;
 714
 715         if (dev->irq[0] != NO_IRQ)
 716                 ret = device_create_file(&dev->dev, &dev_attr_irq0);
 717         if (ret == 0 && dev->irq[1] != NO_IRQ)
 718                 ret = device_create_file(&dev->dev, &dev_attr_irq1);
 719         if (ret == 0)
 720                 return ret;
 721
 722         device_unregister(&dev->dev);
 723
 724  err_release:
 725         release_resource(&dev->res);
 726  err_out:
 727         return ret;
 728 }
 729
 730 /**
 731  *      amba_device_unregister - unregister an AMBA device
 732  *      @dev: AMBA device to remove
 733  *
 734  *      Remove the specified AMBA device from the Linux device
 735  *      manager.  All files associated with this object will be
 736  *      destroyed, and device drivers notified that the device has
 737  *      been removed.  The AMBA device's resources including
 738  *      the amba_device structure will be freed once all
 739  *      references to it have been dropped.
 740  */
 741 void amba_device_unregister(struct amba_device *dev)
 742 {
 743         device_unregister(&dev->dev);
 744 }
 745
 746
 747 struct find_data {
 748         struct amba_device *dev;
 749         struct device *parent;
 750         const char *busid;
 751         unsigned int id;
 752         unsigned int mask;
 753 };
 754
 755 static int amba_find_match(struct device *dev, void *data)
 756 {
 757         struct find_data *d = data;
 758         struct amba_device *pcdev = to_amba_device(dev);
 759         int r;
 760
 761         r = (pcdev->periphid & d->mask) == d->id;
 762         if (d->parent)
 763                 r &= d->parent == dev->parent;
 764         if (d->busid)
 765                 r &= strcmp(dev_name(dev), d->busid) == 0;
 766
 767         if (r) {
 768                 get_device(dev);
 769                 d->dev = pcdev;
 770         }
 771
 772         return r;
 773 }
 774
 775 /**
 776  *      amba_find_device - locate an AMBA device given a bus id
 777  *      @busid: bus id for device (or NULL)
 778  *      @parent: parent device (or NULL)
 779  *      @id: peripheral ID (or 0)
 780  *      @mask: peripheral ID mask (or 0)
 781  *
 782  *      Return the AMBA device corresponding to the supplied parameters.
 783  *      If no device matches, returns NULL.
 784  *
 785  *      NOTE: When a valid device is found, its refcount is
 786  *      incremented, and must be decremented before the returned
 787  *      reference.
 788  */
 789 struct amba_device *
 790 amba_find_device(const char *busid, struct device *parent, unsigned int id,
 791                  unsigned int mask)
 792 {
 793         struct find_data data;
 794
 795         data.dev = NULL;
 796         data.parent = parent;
 797         data.busid = busid;
 798         data.id = id;
 799         data.mask = mask;
 800
 801         bus_for_each_dev(&amba_bustype, NULL, &data, amba_find_match);
 802
 803         return data.dev;
 804 }
 805
 806 /**
 807  *      amba_request_regions - request all mem regions associated with device
 808  *      @dev: amba_device structure for device
 809  *      @name: name, or NULL to use driver name
 810  */
 811 int amba_request_regions(struct amba_device *dev, const char *name)
 812 {
 813         int ret = 0;
 814         u32 size;
 815
 816         if (!name)
 817                 name = dev->dev.driver->name;
 818
 819         size = resource_size(&dev->res);
 820
 821         if (!request_mem_region(dev->res.start, size, name))
 822                 ret = -EBUSY;
 823
 824         return ret;
 825 }
 826
 827 /**
 828  *      amba_release_regions - release mem regions associated with device
 829  *      @dev: amba_device structure for device
 830  *
 831  *      Release regions claimed by a successful call to amba_request_regions.
 832  */
 833 void amba_release_regions(struct amba_device *dev)
 834 {
 835         u32 size;
 836
 837         size = resource_size(&dev->res);
 838         release_mem_region(dev->res.start, size);
 839 }
 840
 841 EXPORT_SYMBOL(amba_driver_register);
 842 EXPORT_SYMBOL(amba_driver_unregister);
 843 EXPORT_SYMBOL(amba_device_register);
 844 EXPORT_SYMBOL(amba_device_unregister);
 845 EXPORT_SYMBOL(amba_find_device);
 846 EXPORT_SYMBOL(amba_request_regions);
 847 EXPORT_SYMBOL(amba_release_regions);