summaryrefslogtreecommitdiff
path: root/drivers/amba/bus.c
blob: 0cf51d57e4ae8782fcb737c2056795939d709584 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
/*
 *  linux/arch/arm/common/amba.c
 *
 *  Copyright (C) 2003 Deep Blue Solutions Ltd, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/pm_domain.h>
#include <linux/amba/bus.h>
#include <linux/sizes.h>
#include <linux/limits.h>
#include <linux/clk/clk-conf.h>
#include <linux/platform_device.h>

#include <asm/irq.h>

#define to_amba_driver(d)	container_of(d, struct amba_driver, drv)

static const struct amba_id *
amba_lookup(const struct amba_id *table, struct amba_device *dev)
{
	int ret = 0;

	while (table->mask) {
		ret = (dev->periphid & table->mask) == table->id;
		if (ret)
			break;
		table++;
	}

	return ret ? table : NULL;
}

static int amba_match(struct device *dev, struct device_driver *drv)
{
	struct amba_device *pcdev = to_amba_device(dev);
	struct amba_driver *pcdrv = to_amba_driver(drv);

	/* When driver_override is set, only bind to the matching driver */
	if (pcdev->driver_override)
		return !strcmp(pcdev->driver_override, drv->name);

	return amba_lookup(pcdrv->id_table, pcdev) != NULL;
}

static int amba_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct amba_device *pcdev = to_amba_device(dev);
	int retval = 0;

	retval = add_uevent_var(env, "AMBA_ID=%08x", pcdev->periphid);
	if (retval)
		return retval;

	retval = add_uevent_var(env, "MODALIAS=amba:d%08X", pcdev->periphid);
	return retval;
}

static ssize_t driver_override_show(struct device *_dev,
				    struct device_attribute *attr, char *buf)
{
	struct amba_device *dev = to_amba_device(_dev);
	ssize_t len;

	device_lock(_dev);
	len = sprintf(buf, "%s\n", dev->driver_override);
	device_unlock(_dev);
	return len;
}

static ssize_t driver_override_store(struct device *_dev,
				     struct device_attribute *attr,
				     const char *buf, size_t count)
{
	struct amba_device *dev = to_amba_device(_dev);
	char *driver_override, *old, *cp;

	/* We need to keep extra room for a newline */
	if (count >= (PAGE_SIZE - 1))
		return -EINVAL;

	driver_override = kstrndup(buf, count, GFP_KERNEL);
	if (!driver_override)
		return -ENOMEM;

	cp = strchr(driver_override, '\n');
	if (cp)
		*cp = '\0';

	device_lock(_dev);
	old = dev->driver_override;
	if (strlen(driver_override)) {
		dev->driver_override = driver_override;
	} else {
	       kfree(driver_override);
	       dev->driver_override = NULL;
	}
	device_unlock(_dev);

	kfree(old);

	return count;
}
static DEVICE_ATTR_RW(driver_override);

#define amba_attr_func(name,fmt,arg...)					\
static ssize_t name##_show(struct device *_dev,				\
			   struct device_attribute *attr, char *buf)	\
{									\
	struct amba_device *dev = to_amba_device(_dev);			\
	return sprintf(buf, fmt, arg);					\
}									\
static DEVICE_ATTR_RO(name)

amba_attr_func(id, "%08x\n", dev->periphid);
amba_attr_func(irq0, "%u\n", dev->irq[0]);
amba_attr_func(irq1, "%u\n", dev->irq[1]);
amba_attr_func(resource, "\t%016llx\t%016llx\t%016lx\n",
	 (unsigned long long)dev->res.start, (unsigned long long)dev->res.end,
	 dev->res.flags);

static struct attribute *amba_dev_attrs[] = {
	&dev_attr_id.attr,
	&dev_attr_resource.attr,
	&dev_attr_driver_override.attr,
	NULL,
};
ATTRIBUTE_GROUPS(amba_dev);

#ifdef CONFIG_PM
/*
 * Hooks to provide runtime PM of the pclk (bus clock).  It is safe to
 * enable/disable the bus clock at runtime PM suspend/resume as this
 * does not result in loss of context.
 */
static int amba_pm_runtime_suspend(struct device *dev)
{
	struct amba_device *pcdev = to_amba_device(dev);
	int ret = pm_generic_runtime_suspend(dev);

	if (ret == 0 && dev->driver) {
		if (pm_runtime_is_irq_safe(dev))
			clk_disable(pcdev->pclk);
		else
			clk_disable_unprepare(pcdev->pclk);
	}

	return ret;
}

static int amba_pm_runtime_resume(struct device *dev)
{
	struct amba_device *pcdev = to_amba_device(dev);
	int ret;

	if (dev->driver) {
		if (pm_runtime_is_irq_safe(dev))
			ret = clk_enable(pcdev->pclk);
		else
			ret = clk_prepare_enable(pcdev->pclk);
		/* Failure is probably fatal to the system, but... */
		if (ret)
			return ret;
	}

	return pm_generic_runtime_resume(dev);
}
#endif /* CONFIG_PM */

static const struct dev_pm_ops amba_pm = {
	.suspend	= pm_generic_suspend,
	.resume		= pm_generic_resume,
	.freeze		= pm_generic_freeze,
	.thaw		= pm_generic_thaw,
	.poweroff	= pm_generic_poweroff,
	.restore	= pm_generic_restore,
	SET_RUNTIME_PM_OPS(
		amba_pm_runtime_suspend,
		amba_pm_runtime_resume,
		NULL
	)
};

/*
 * Primecells are part of the Advanced Microcontroller Bus Architecture,
 * so we call the bus "amba".
 * DMA configuration for platform and AMBA bus is same. So here we reuse
 * platform's DMA config routine.
 */
struct bus_type amba_bustype = {
	.name		= "amba",
	.dev_groups	= amba_dev_groups,
	.match		= amba_match,
	.uevent		= amba_uevent,
	.dma_configure	= platform_dma_configure,
	.pm		= &amba_pm,
};

static int __init amba_init(void)
{
	return bus_register(&amba_bustype);
}

postcore_initcall(amba_init);

static int amba_get_enable_pclk(struct amba_device *pcdev)
{
	int ret;

	pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
	if (IS_ERR(pcdev->pclk))
		return PTR_ERR(pcdev->pclk);

	ret = clk_prepare_enable(pcdev->pclk);
	if (ret)
		clk_put(pcdev->pclk);

	return ret;
}

static void amba_put_disable_pclk(struct amba_device *pcdev)
{
	clk_disable_unprepare(pcdev->pclk);
	clk_put(pcdev->pclk);
}

/*
 * These are the device model conversion veneers; they convert the
 * device model structures to our more specific structures.
 */
static int amba_probe(struct device *dev)
{
	struct amba_device *pcdev = to_amba_device(dev);
	struct amba_driver *pcdrv = to_amba_driver(dev->driver);
	const struct amba_id *id = amba_lookup(pcdrv->id_table, pcdev);
	int ret;

	do {
		ret = of_clk_set_defaults(dev->of_node, false);
		if (ret < 0)
			break;

		ret = dev_pm_domain_attach(dev, true);
		if (ret)
			break;

		ret = amba_get_enable_pclk(pcdev);
		if (ret) {
			dev_pm_domain_detach(dev, true);
			break;
		}

		pm_runtime_get_noresume(dev);
		pm_runtime_set_active(dev);
		pm_runtime_enable(dev);

		ret = pcdrv->probe(pcdev, id);
		if (ret == 0)
			break;

		pm_runtime_disable(dev);
		pm_runtime_set_suspended(dev);
		pm_runtime_put_noidle(dev);

		amba_put_disable_pclk(pcdev);
		dev_pm_domain_detach(dev, true);
	} while (0);

	return ret;
}

static int amba_remove(struct device *dev)
{
	struct amba_device *pcdev = to_amba_device(dev);
	struct amba_driver *drv = to_amba_driver(dev->driver);
	int ret;

	pm_runtime_get_sync(dev);
	ret = drv->remove(pcdev);
	pm_runtime_put_noidle(dev);

	/* Undo the runtime PM settings in amba_probe() */
	pm_runtime_disable(dev);
	pm_runtime_set_suspended(dev);
	pm_runtime_put_noidle(dev);

	amba_put_disable_pclk(pcdev);
	dev_pm_domain_detach(dev, true);

	return ret;
}

static void amba_shutdown(struct device *dev)
{
	struct amba_driver *drv = to_amba_driver(dev->driver);
	drv->shutdown(to_amba_device(dev));
}

/**
 *	amba_driver_register - register an AMBA device driver
 *	@drv: amba device driver structure
 *
 *	Register an AMBA device driver with the Linux device model
 *	core.  If devices pre-exist, the drivers probe function will
 *	be called.
 */
int amba_driver_register(struct amba_driver *drv)
{
	drv->drv.bus = &amba_bustype;

#define SETFN(fn)	if (drv->fn) drv->drv.fn = amba_##fn
	SETFN(probe);
	SETFN(remove);
	SETFN(shutdown);

	return driver_register(&drv->drv);
}

/**
 *	amba_driver_unregister - remove an AMBA device driver
 *	@drv: AMBA device driver structure to remove
 *
 *	Unregister an AMBA device driver from the Linux device
 *	model.  The device model will call the drivers remove function
 *	for each device the device driver is currently handling.
 */
void amba_driver_unregister(struct amba_driver *drv)
{
	driver_unregister(&drv->drv);
}


static void amba_device_release(struct device *dev)
{
	struct amba_device *d = to_amba_device(dev);

	if (d->res.parent)
		release_resource(&d->res);
	kfree(d);
}

static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
{
	u32 size;
	void __iomem *tmp;
	int i, ret;

	WARN_ON(dev->irq[0] == (unsigned int)-1);
	WARN_ON(dev->irq[1] == (unsigned int)-1);

	ret = request_resource(parent, &dev->res);
	if (ret)
		goto err_out;

	/* Hard-coded primecell ID instead of plug-n-play */
	if (dev->periphid != 0)
		goto skip_probe;

	/*
	 * Dynamically calculate the size of the resource
	 * and use this for iomap
	 */
	size = resource_size(&dev->res);
	tmp = ioremap(dev->res.start, size);
	if (!tmp) {
		ret = -ENOMEM;
		goto err_release;
	}

	ret = dev_pm_domain_attach(&dev->dev, true);
	if (ret) {
		iounmap(tmp);
		goto err_release;
	}

	ret = amba_get_enable_pclk(dev);
	if (ret == 0) {
		u32 pid, cid;

		/*
		 * Read pid and cid based on size of resource
		 * they are located at end of region
		 */
		for (pid = 0, i = 0; i < 4; i++)
			pid |= (readl(tmp + size - 0x20 + 4 * i) & 255) <<
				(i * 8);
		for (cid = 0, i = 0; i < 4; i++)
			cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) <<
				(i * 8);

		amba_put_disable_pclk(dev);

		if (cid == AMBA_CID || cid == CORESIGHT_CID)
			dev->periphid = pid;

		if (!dev->periphid)
			ret = -ENODEV;
	}

	iounmap(tmp);
	dev_pm_domain_detach(&dev->dev, true);

	if (ret)
		goto err_release;

 skip_probe:
	ret = device_add(&dev->dev);
	if (ret)
		goto err_release;

	if (dev->irq[0])
		ret = device_create_file(&dev->dev, &dev_attr_irq0);
	if (ret == 0 && dev->irq[1])
		ret = device_create_file(&dev->dev, &dev_attr_irq1);
	if (ret == 0)
		return ret;

	device_unregister(&dev->dev);

 err_release:
	release_resource(&dev->res);
 err_out:
	return ret;
}

/*
 * Registration of AMBA device require reading its pid and cid registers.
 * To do this, the device must be turned on (if it is a part of power domain)
 * and have clocks enabled. However in some cases those resources might not be
 * yet available. Returning EPROBE_DEFER is not a solution in such case,
 * because callers don't handle this special error code. Instead such devices
 * are added to the special list and their registration is retried from
 * periodic worker, until all resources are available and registration succeeds.
 */
struct deferred_device {
	struct amba_device *dev;
	struct resource *parent;
	struct list_head node;
};

static LIST_HEAD(deferred_devices);
static DEFINE_MUTEX(deferred_devices_lock);

static void amba_deferred_retry_func(struct work_struct *dummy);
static DECLARE_DELAYED_WORK(deferred_retry_work, amba_deferred_retry_func);

#define DEFERRED_DEVICE_TIMEOUT (msecs_to_jiffies(5 * 1000))

static void amba_deferred_retry_func(struct work_struct *dummy)
{
	struct deferred_device *ddev, *tmp;

	mutex_lock(&deferred_devices_lock);

	list_for_each_entry_safe(ddev, tmp, &deferred_devices, node) {
		int ret = amba_device_try_add(ddev->dev, ddev->parent);

		if (ret == -EPROBE_DEFER)
			continue;

		list_del_init(&ddev->node);
		kfree(ddev);
	}

	if (!list_empty(&deferred_devices))
		schedule_delayed_work(&deferred_retry_work,
				      DEFERRED_DEVICE_TIMEOUT);

	mutex_unlock(&deferred_devices_lock);
}

/**
 *	amba_device_add - add a previously allocated AMBA device structure
 *	@dev: AMBA device allocated by amba_device_alloc
 *	@parent: resource parent for this devices resources
 *
 *	Claim the resource, and read the device cell ID if not already
 *	initialized.  Register the AMBA device with the Linux device
 *	manager.
 */
int amba_device_add(struct amba_device *dev, struct resource *parent)
{
	int ret = amba_device_try_add(dev, parent);

	if (ret == -EPROBE_DEFER) {
		struct deferred_device *ddev;

		ddev = kmalloc(sizeof(*ddev), GFP_KERNEL);
		if (!ddev)
			return -ENOMEM;

		ddev->dev = dev;
		ddev->parent = parent;
		ret = 0;

		mutex_lock(&deferred_devices_lock);

		if (list_empty(&deferred_devices))
			schedule_delayed_work(&deferred_retry_work,
					      DEFERRED_DEVICE_TIMEOUT);
		list_add_tail(&ddev->node, &deferred_devices);

		mutex_unlock(&deferred_devices_lock);
	}
	return ret;
}
EXPORT_SYMBOL_GPL(amba_device_add);

static struct amba_device *
amba_aphb_device_add(struct device *parent, const char *name,
		     resource_size_t base, size_t size, int irq1, int irq2,
		     void *pdata, unsigned int periphid, u64 dma_mask,
		     struct resource *resbase)
{
	struct amba_device *dev;
	int ret;

	dev = amba_device_alloc(name, base, size);
	if (!dev)
		return ERR_PTR(-ENOMEM);

	dev->dev.coherent_dma_mask = dma_mask;
	dev->irq[0] = irq1;
	dev->irq[1] = irq2;
	dev->periphid = periphid;
	dev->dev.platform_data = pdata;
	dev->dev.parent = parent;

	ret = amba_device_add(dev, resbase);
	if (ret) {
		amba_device_put(dev);
		return ERR_PTR(ret);
	}

	return dev;
}

struct amba_device *
amba_apb_device_add(struct device *parent, const char *name,
		    resource_size_t base, size_t size, int irq1, int irq2,
		    void *pdata, unsigned int periphid)
{
	return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
				    periphid, 0, &iomem_resource);
}
EXPORT_SYMBOL_GPL(amba_apb_device_add);

struct amba_device *
amba_ahb_device_add(struct device *parent, const char *name,
		    resource_size_t base, size_t size, int irq1, int irq2,
		    void *pdata, unsigned int periphid)
{
	return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
				    periphid, ~0ULL, &iomem_resource);
}
EXPORT_SYMBOL_GPL(amba_ahb_device_add);

struct amba_device *
amba_apb_device_add_res(struct device *parent, const char *name,
			resource_size_t base, size_t size, int irq1,
			int irq2, void *pdata, unsigned int periphid,
			struct resource *resbase)
{
	return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
				    periphid, 0, resbase);
}
EXPORT_SYMBOL_GPL(amba_apb_device_add_res);

struct amba_device *
amba_ahb_device_add_res(struct device *parent, const char *name,
			resource_size_t base, size_t size, int irq1,
			int irq2, void *pdata, unsigned int periphid,
			struct resource *resbase)
{
	return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
				    periphid, ~0ULL, resbase);
}
EXPORT_SYMBOL_GPL(amba_ahb_device_add_res);


static void amba_device_initialize(struct amba_device *dev, const char *name)
{
	device_initialize(&dev->dev);
	if (name)
		dev_set_name(&dev->dev, "%s", name);
	dev->dev.release = amba_device_release;
	dev->dev.bus = &amba_bustype;
	dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
	dev->res.name = dev_name(&dev->dev);
}

/**
 *	amba_device_alloc - allocate an AMBA device
 *	@name: sysfs name of the AMBA device
 *	@base: base of AMBA device
 *	@size: size of AMBA device
 *
 *	Allocate and initialize an AMBA device structure.  Returns %NULL
 *	on failure.
 */
struct amba_device *amba_device_alloc(const char *name, resource_size_t base,
	size_t size)
{
	struct amba_device *dev;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (dev) {
		amba_device_initialize(dev, name);
		dev->res.start = base;
		dev->res.end = base + size - 1;
		dev->res.flags = IORESOURCE_MEM;
	}

	return dev;
}
EXPORT_SYMBOL_GPL(amba_device_alloc);

/**
 *	amba_device_register - register an AMBA device
 *	@dev: AMBA device to register
 *	@parent: parent memory resource
 *
 *	Setup the AMBA device, reading the cell ID if present.
 *	Claim the resource, and register the AMBA device with
 *	the Linux device manager.
 */
int amba_device_register(struct amba_device *dev, struct resource *parent)
{
	amba_device_initialize(dev, dev->dev.init_name);
	dev->dev.init_name = NULL;

	return amba_device_add(dev, parent);
}

/**
 *	amba_device_put - put an AMBA device
 *	@dev: AMBA device to put
 */
void amba_device_put(struct amba_device *dev)
{
	put_device(&dev->dev);
}
EXPORT_SYMBOL_GPL(amba_device_put);

/**
 *	amba_device_unregister - unregister an AMBA device
 *	@dev: AMBA device to remove
 *
 *	Remove the specified AMBA device from the Linux device
 *	manager.  All files associated with this object will be
 *	destroyed, and device drivers notified that the device has
 *	been removed.  The AMBA device's resources including
 *	the amba_device structure will be freed once all
 *	references to it have been dropped.
 */
void amba_device_unregister(struct amba_device *dev)
{
	device_unregister(&dev->dev);
}


struct find_data {
	struct amba_device *dev;
	struct device *parent;
	const char *busid;
	unsigned int id;
	unsigned int mask;
};

static int amba_find_match(struct device *dev, void *data)
{
	struct find_data *d = data;
	struct amba_device *pcdev = to_amba_device(dev);
	int r;

	r = (pcdev->periphid & d->mask) == d->id;
	if (d->parent)
		r &= d->parent == dev->parent;
	if (d->busid)
		r &= strcmp(dev_name(dev), d->busid) == 0;

	if (r) {
		get_device(dev);
		d->dev = pcdev;
	}

	return r;
}

/**
 *	amba_find_device - locate an AMBA device given a bus id
 *	@busid: bus id for device (or NULL)
 *	@parent: parent device (or NULL)
 *	@id: peripheral ID (or 0)
 *	@mask: peripheral ID mask (or 0)
 *
 *	Return the AMBA device corresponding to the supplied parameters.
 *	If no device matches, returns NULL.
 *
 *	NOTE: When a valid device is found, its refcount is
 *	incremented, and must be decremented before the returned
 *	reference.
 */
struct amba_device *
amba_find_device(const char *busid, struct device *parent, unsigned int id,
		 unsigned int mask)
{
	struct find_data data;

	data.dev = NULL;
	data.parent = parent;
	data.busid = busid;
	data.id = id;
	data.mask = mask;

	bus_for_each_dev(&amba_bustype, NULL, &data, amba_find_match);

	return data.dev;
}

/**
 *	amba_request_regions - request all mem regions associated with device
 *	@dev: amba_device structure for device
 *	@name: name, or NULL to use driver name
 */
int amba_request_regions(struct amba_device *dev, const char *name)
{
	int ret = 0;
	u32 size;

	if (!name)
		name = dev->dev.driver->name;

	size = resource_size(&dev->res);

	if (!request_mem_region(dev->res.start, size, name))
		ret = -EBUSY;

	return ret;
}

/**
 *	amba_release_regions - release mem regions associated with device
 *	@dev: amba_device structure for device
 *
 *	Release regions claimed by a successful call to amba_request_regions.
 */
void amba_release_regions(struct amba_device *dev)
{
	u32 size;

	size = resource_size(&dev->res);
	release_mem_region(dev->res.start, size);
}

EXPORT_SYMBOL(amba_driver_register);
EXPORT_SYMBOL(amba_driver_unregister);
EXPORT_SYMBOL(amba_device_register);
EXPORT_SYMBOL(amba_device_unregister);
EXPORT_SYMBOL(amba_find_device);
EXPORT_SYMBOL(amba_request_regions);
EXPORT_SYMBOL(amba_release_regions);