xref: /openbmc/linux/drivers/amba/bus.c (revision e312cbdc)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/common/amba.c
4  *
5  *  Copyright (C) 2003 Deep Blue Solutions Ltd, All Rights Reserved.
6  */
7 #include <linux/module.h>
8 #include <linux/init.h>
9 #include <linux/device.h>
10 #include <linux/string.h>
11 #include <linux/slab.h>
12 #include <linux/io.h>
13 #include <linux/pm.h>
14 #include <linux/pm_runtime.h>
15 #include <linux/pm_domain.h>
16 #include <linux/amba/bus.h>
17 #include <linux/sizes.h>
18 #include <linux/limits.h>
19 #include <linux/clk/clk-conf.h>
20 #include <linux/platform_device.h>
21 #include <linux/reset.h>
22 #include <linux/of_irq.h>
23 #include <linux/of_device.h>
24 #include <linux/acpi.h>
25 #include <linux/iommu.h>
26 #include <linux/dma-map-ops.h>
27 
28 #define to_amba_driver(d)	container_of(d, struct amba_driver, drv)
29 
30 /* called on periphid match and class 0x9 coresight device. */
31 static int
amba_cs_uci_id_match(const struct amba_id * table,struct amba_device * dev)32 amba_cs_uci_id_match(const struct amba_id *table, struct amba_device *dev)
33 {
34 	int ret = 0;
35 	struct amba_cs_uci_id *uci;
36 
37 	uci = table->data;
38 
39 	/* no table data or zero mask - return match on periphid */
40 	if (!uci || (uci->devarch_mask == 0))
41 		return 1;
42 
43 	/* test against read devtype and masked devarch value */
44 	ret = (dev->uci.devtype == uci->devtype) &&
45 		((dev->uci.devarch & uci->devarch_mask) == uci->devarch);
46 	return ret;
47 }
48 
49 static const struct amba_id *
amba_lookup(const struct amba_id * table,struct amba_device * dev)50 amba_lookup(const struct amba_id *table, struct amba_device *dev)
51 {
52 	while (table->mask) {
53 		if (((dev->periphid & table->mask) == table->id) &&
54 			((dev->cid != CORESIGHT_CID) ||
55 			 (amba_cs_uci_id_match(table, dev))))
56 			return table;
57 		table++;
58 	}
59 	return NULL;
60 }
61 
amba_get_enable_pclk(struct amba_device * pcdev)62 static int amba_get_enable_pclk(struct amba_device *pcdev)
63 {
64 	int ret;
65 
66 	pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
67 	if (IS_ERR(pcdev->pclk))
68 		return PTR_ERR(pcdev->pclk);
69 
70 	ret = clk_prepare_enable(pcdev->pclk);
71 	if (ret)
72 		clk_put(pcdev->pclk);
73 
74 	return ret;
75 }
76 
amba_put_disable_pclk(struct amba_device * pcdev)77 static void amba_put_disable_pclk(struct amba_device *pcdev)
78 {
79 	clk_disable_unprepare(pcdev->pclk);
80 	clk_put(pcdev->pclk);
81 }
82 
83 
driver_override_show(struct device * _dev,struct device_attribute * attr,char * buf)84 static ssize_t driver_override_show(struct device *_dev,
85 				    struct device_attribute *attr, char *buf)
86 {
87 	struct amba_device *dev = to_amba_device(_dev);
88 	ssize_t len;
89 
90 	device_lock(_dev);
91 	len = sprintf(buf, "%s\n", dev->driver_override);
92 	device_unlock(_dev);
93 	return len;
94 }
95 
driver_override_store(struct device * _dev,struct device_attribute * attr,const char * buf,size_t count)96 static ssize_t driver_override_store(struct device *_dev,
97 				     struct device_attribute *attr,
98 				     const char *buf, size_t count)
99 {
100 	struct amba_device *dev = to_amba_device(_dev);
101 	int ret;
102 
103 	ret = driver_set_override(_dev, &dev->driver_override, buf, count);
104 	if (ret)
105 		return ret;
106 
107 	return count;
108 }
109 static DEVICE_ATTR_RW(driver_override);
110 
111 #define amba_attr_func(name,fmt,arg...)					\
112 static ssize_t name##_show(struct device *_dev,				\
113 			   struct device_attribute *attr, char *buf)	\
114 {									\
115 	struct amba_device *dev = to_amba_device(_dev);			\
116 	return sprintf(buf, fmt, arg);					\
117 }									\
118 static DEVICE_ATTR_RO(name)
119 
120 amba_attr_func(id, "%08x\n", dev->periphid);
121 amba_attr_func(resource, "\t%016llx\t%016llx\t%016lx\n",
122 	 (unsigned long long)dev->res.start, (unsigned long long)dev->res.end,
123 	 dev->res.flags);
124 
125 static struct attribute *amba_dev_attrs[] = {
126 	&dev_attr_id.attr,
127 	&dev_attr_resource.attr,
128 	&dev_attr_driver_override.attr,
129 	NULL,
130 };
131 ATTRIBUTE_GROUPS(amba_dev);
132 
amba_read_periphid(struct amba_device * dev)133 static int amba_read_periphid(struct amba_device *dev)
134 {
135 	struct reset_control *rstc;
136 	u32 size, pid, cid;
137 	void __iomem *tmp;
138 	int i, ret;
139 
140 	ret = dev_pm_domain_attach(&dev->dev, true);
141 	if (ret) {
142 		dev_dbg(&dev->dev, "can't get PM domain: %d\n", ret);
143 		goto err_out;
144 	}
145 
146 	ret = amba_get_enable_pclk(dev);
147 	if (ret) {
148 		dev_dbg(&dev->dev, "can't get pclk: %d\n", ret);
149 		goto err_pm;
150 	}
151 
152 	/*
153 	 * Find reset control(s) of the amba bus and de-assert them.
154 	 */
155 	rstc = of_reset_control_array_get_optional_shared(dev->dev.of_node);
156 	if (IS_ERR(rstc)) {
157 		ret = PTR_ERR(rstc);
158 		if (ret != -EPROBE_DEFER)
159 			dev_err(&dev->dev, "can't get reset: %d\n", ret);
160 		goto err_clk;
161 	}
162 	reset_control_deassert(rstc);
163 	reset_control_put(rstc);
164 
165 	size = resource_size(&dev->res);
166 	tmp = ioremap(dev->res.start, size);
167 	if (!tmp) {
168 		ret = -ENOMEM;
169 		goto err_clk;
170 	}
171 
172 	/*
173 	 * Read pid and cid based on size of resource
174 	 * they are located at end of region
175 	 */
176 	for (pid = 0, i = 0; i < 4; i++)
177 		pid |= (readl(tmp + size - 0x20 + 4 * i) & 255) << (i * 8);
178 	for (cid = 0, i = 0; i < 4; i++)
179 		cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) << (i * 8);
180 
181 	if (cid == CORESIGHT_CID) {
182 		/* set the base to the start of the last 4k block */
183 		void __iomem *csbase = tmp + size - 4096;
184 
185 		dev->uci.devarch = readl(csbase + UCI_REG_DEVARCH_OFFSET);
186 		dev->uci.devtype = readl(csbase + UCI_REG_DEVTYPE_OFFSET) & 0xff;
187 	}
188 
189 	if (cid == AMBA_CID || cid == CORESIGHT_CID) {
190 		dev->periphid = pid;
191 		dev->cid = cid;
192 	}
193 
194 	if (!dev->periphid)
195 		ret = -ENODEV;
196 
197 	iounmap(tmp);
198 
199 err_clk:
200 	amba_put_disable_pclk(dev);
201 err_pm:
202 	dev_pm_domain_detach(&dev->dev, true);
203 err_out:
204 	return ret;
205 }
206 
amba_match(struct device * dev,struct device_driver * drv)207 static int amba_match(struct device *dev, struct device_driver *drv)
208 {
209 	struct amba_device *pcdev = to_amba_device(dev);
210 	struct amba_driver *pcdrv = to_amba_driver(drv);
211 
212 	mutex_lock(&pcdev->periphid_lock);
213 	if (!pcdev->periphid) {
214 		int ret = amba_read_periphid(pcdev);
215 
216 		/*
217 		 * Returning any error other than -EPROBE_DEFER from bus match
218 		 * can cause driver registration failure. So, if there's a
219 		 * permanent failure in reading pid and cid, simply map it to
220 		 * -EPROBE_DEFER.
221 		 */
222 		if (ret) {
223 			mutex_unlock(&pcdev->periphid_lock);
224 			return -EPROBE_DEFER;
225 		}
226 		dev_set_uevent_suppress(dev, false);
227 		kobject_uevent(&dev->kobj, KOBJ_ADD);
228 	}
229 	mutex_unlock(&pcdev->periphid_lock);
230 
231 	/* When driver_override is set, only bind to the matching driver */
232 	if (pcdev->driver_override)
233 		return !strcmp(pcdev->driver_override, drv->name);
234 
235 	return amba_lookup(pcdrv->id_table, pcdev) != NULL;
236 }
237 
amba_uevent(const struct device * dev,struct kobj_uevent_env * env)238 static int amba_uevent(const struct device *dev, struct kobj_uevent_env *env)
239 {
240 	const struct amba_device *pcdev = to_amba_device(dev);
241 	int retval = 0;
242 
243 	retval = add_uevent_var(env, "AMBA_ID=%08x", pcdev->periphid);
244 	if (retval)
245 		return retval;
246 
247 	retval = add_uevent_var(env, "MODALIAS=amba:d%08X", pcdev->periphid);
248 	return retval;
249 }
250 
of_amba_device_decode_irq(struct amba_device * dev)251 static int of_amba_device_decode_irq(struct amba_device *dev)
252 {
253 	struct device_node *node = dev->dev.of_node;
254 	int i, irq = 0;
255 
256 	if (IS_ENABLED(CONFIG_OF_IRQ) && node) {
257 		/* Decode the IRQs and address ranges */
258 		for (i = 0; i < AMBA_NR_IRQS; i++) {
259 			irq = of_irq_get(node, i);
260 			if (irq < 0) {
261 				if (irq == -EPROBE_DEFER)
262 					return irq;
263 				irq = 0;
264 			}
265 
266 			dev->irq[i] = irq;
267 		}
268 	}
269 
270 	return 0;
271 }
272 
273 /*
274  * These are the device model conversion veneers; they convert the
275  * device model structures to our more specific structures.
276  */
amba_probe(struct device * dev)277 static int amba_probe(struct device *dev)
278 {
279 	struct amba_device *pcdev = to_amba_device(dev);
280 	struct amba_driver *pcdrv = to_amba_driver(dev->driver);
281 	const struct amba_id *id = amba_lookup(pcdrv->id_table, pcdev);
282 	int ret;
283 
284 	do {
285 		ret = of_amba_device_decode_irq(pcdev);
286 		if (ret)
287 			break;
288 
289 		ret = of_clk_set_defaults(dev->of_node, false);
290 		if (ret < 0)
291 			break;
292 
293 		ret = dev_pm_domain_attach(dev, true);
294 		if (ret)
295 			break;
296 
297 		ret = amba_get_enable_pclk(pcdev);
298 		if (ret) {
299 			dev_pm_domain_detach(dev, true);
300 			break;
301 		}
302 
303 		pm_runtime_get_noresume(dev);
304 		pm_runtime_set_active(dev);
305 		pm_runtime_enable(dev);
306 
307 		ret = pcdrv->probe(pcdev, id);
308 		if (ret == 0)
309 			break;
310 
311 		pm_runtime_disable(dev);
312 		pm_runtime_set_suspended(dev);
313 		pm_runtime_put_noidle(dev);
314 
315 		amba_put_disable_pclk(pcdev);
316 		dev_pm_domain_detach(dev, true);
317 	} while (0);
318 
319 	return ret;
320 }
321 
amba_remove(struct device * dev)322 static void amba_remove(struct device *dev)
323 {
324 	struct amba_device *pcdev = to_amba_device(dev);
325 	struct amba_driver *drv = to_amba_driver(dev->driver);
326 
327 	pm_runtime_get_sync(dev);
328 	if (drv->remove)
329 		drv->remove(pcdev);
330 	pm_runtime_put_noidle(dev);
331 
332 	/* Undo the runtime PM settings in amba_probe() */
333 	pm_runtime_disable(dev);
334 	pm_runtime_set_suspended(dev);
335 	pm_runtime_put_noidle(dev);
336 
337 	amba_put_disable_pclk(pcdev);
338 	dev_pm_domain_detach(dev, true);
339 }
340 
amba_shutdown(struct device * dev)341 static void amba_shutdown(struct device *dev)
342 {
343 	struct amba_driver *drv;
344 
345 	if (!dev->driver)
346 		return;
347 
348 	drv = to_amba_driver(dev->driver);
349 	if (drv->shutdown)
350 		drv->shutdown(to_amba_device(dev));
351 }
352 
amba_dma_configure(struct device * dev)353 static int amba_dma_configure(struct device *dev)
354 {
355 	struct amba_driver *drv = to_amba_driver(dev->driver);
356 	enum dev_dma_attr attr;
357 	int ret = 0;
358 
359 	if (dev->of_node) {
360 		ret = of_dma_configure(dev, dev->of_node, true);
361 	} else if (has_acpi_companion(dev)) {
362 		attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
363 		ret = acpi_dma_configure(dev, attr);
364 	}
365 
366 	if (!ret && !drv->driver_managed_dma) {
367 		ret = iommu_device_use_default_domain(dev);
368 		if (ret)
369 			arch_teardown_dma_ops(dev);
370 	}
371 
372 	return ret;
373 }
374 
amba_dma_cleanup(struct device * dev)375 static void amba_dma_cleanup(struct device *dev)
376 {
377 	struct amba_driver *drv = to_amba_driver(dev->driver);
378 
379 	if (!drv->driver_managed_dma)
380 		iommu_device_unuse_default_domain(dev);
381 }
382 
383 #ifdef CONFIG_PM
384 /*
385  * Hooks to provide runtime PM of the pclk (bus clock).  It is safe to
386  * enable/disable the bus clock at runtime PM suspend/resume as this
387  * does not result in loss of context.
388  */
amba_pm_runtime_suspend(struct device * dev)389 static int amba_pm_runtime_suspend(struct device *dev)
390 {
391 	struct amba_device *pcdev = to_amba_device(dev);
392 	int ret = pm_generic_runtime_suspend(dev);
393 
394 	if (ret == 0 && dev->driver) {
395 		if (pm_runtime_is_irq_safe(dev))
396 			clk_disable(pcdev->pclk);
397 		else
398 			clk_disable_unprepare(pcdev->pclk);
399 	}
400 
401 	return ret;
402 }
403 
amba_pm_runtime_resume(struct device * dev)404 static int amba_pm_runtime_resume(struct device *dev)
405 {
406 	struct amba_device *pcdev = to_amba_device(dev);
407 	int ret;
408 
409 	if (dev->driver) {
410 		if (pm_runtime_is_irq_safe(dev))
411 			ret = clk_enable(pcdev->pclk);
412 		else
413 			ret = clk_prepare_enable(pcdev->pclk);
414 		/* Failure is probably fatal to the system, but... */
415 		if (ret)
416 			return ret;
417 	}
418 
419 	return pm_generic_runtime_resume(dev);
420 }
421 #endif /* CONFIG_PM */
422 
423 static const struct dev_pm_ops amba_pm = {
424 	SET_RUNTIME_PM_OPS(
425 		amba_pm_runtime_suspend,
426 		amba_pm_runtime_resume,
427 		NULL
428 	)
429 };
430 
431 /*
432  * Primecells are part of the Advanced Microcontroller Bus Architecture,
433  * so we call the bus "amba".
434  * DMA configuration for platform and AMBA bus is same. So here we reuse
435  * platform's DMA config routine.
436  */
437 struct bus_type amba_bustype = {
438 	.name		= "amba",
439 	.dev_groups	= amba_dev_groups,
440 	.match		= amba_match,
441 	.uevent		= amba_uevent,
442 	.probe		= amba_probe,
443 	.remove		= amba_remove,
444 	.shutdown	= amba_shutdown,
445 	.dma_configure	= amba_dma_configure,
446 	.dma_cleanup	= amba_dma_cleanup,
447 	.pm		= &amba_pm,
448 };
449 EXPORT_SYMBOL_GPL(amba_bustype);
450 
amba_init(void)451 static int __init amba_init(void)
452 {
453 	return bus_register(&amba_bustype);
454 }
455 
456 postcore_initcall(amba_init);
457 
amba_proxy_probe(struct amba_device * adev,const struct amba_id * id)458 static int amba_proxy_probe(struct amba_device *adev,
459 			    const struct amba_id *id)
460 {
461 	WARN(1, "Stub driver should never match any device.\n");
462 	return -ENODEV;
463 }
464 
465 static const struct amba_id amba_stub_drv_ids[] = {
466 	{ 0, 0 },
467 };
468 
469 static struct amba_driver amba_proxy_drv = {
470 	.drv = {
471 		.name = "amba-proxy",
472 	},
473 	.probe = amba_proxy_probe,
474 	.id_table = amba_stub_drv_ids,
475 };
476 
amba_stub_drv_init(void)477 static int __init amba_stub_drv_init(void)
478 {
479 	if (!IS_ENABLED(CONFIG_MODULES))
480 		return 0;
481 
482 	/*
483 	 * The amba_match() function will get called only if there is at least
484 	 * one amba driver registered. If all amba drivers are modules and are
485 	 * only loaded based on uevents, then we'll hit a chicken-and-egg
486 	 * situation where amba_match() is waiting on drivers and drivers are
487 	 * waiting on amba_match(). So, register a stub driver to make sure
488 	 * amba_match() is called even if no amba driver has been registered.
489 	 */
490 	return amba_driver_register(&amba_proxy_drv);
491 }
492 late_initcall_sync(amba_stub_drv_init);
493 
494 /**
495  *	amba_driver_register - register an AMBA device driver
496  *	@drv: amba device driver structure
497  *
498  *	Register an AMBA device driver with the Linux device model
499  *	core.  If devices pre-exist, the drivers probe function will
500  *	be called.
501  */
amba_driver_register(struct amba_driver * drv)502 int amba_driver_register(struct amba_driver *drv)
503 {
504 	if (!drv->probe)
505 		return -EINVAL;
506 
507 	drv->drv.bus = &amba_bustype;
508 
509 	return driver_register(&drv->drv);
510 }
511 EXPORT_SYMBOL(amba_driver_register);
512 
513 /**
514  *	amba_driver_unregister - remove an AMBA device driver
515  *	@drv: AMBA device driver structure to remove
516  *
517  *	Unregister an AMBA device driver from the Linux device
518  *	model.  The device model will call the drivers remove function
519  *	for each device the device driver is currently handling.
520  */
amba_driver_unregister(struct amba_driver * drv)521 void amba_driver_unregister(struct amba_driver *drv)
522 {
523 	driver_unregister(&drv->drv);
524 }
525 EXPORT_SYMBOL(amba_driver_unregister);
526 
amba_device_release(struct device * dev)527 static void amba_device_release(struct device *dev)
528 {
529 	struct amba_device *d = to_amba_device(dev);
530 
531 	of_node_put(d->dev.of_node);
532 	if (d->res.parent)
533 		release_resource(&d->res);
534 	mutex_destroy(&d->periphid_lock);
535 	kfree(d);
536 }
537 
538 /**
539  *	amba_device_add - add a previously allocated AMBA device structure
540  *	@dev: AMBA device allocated by amba_device_alloc
541  *	@parent: resource parent for this devices resources
542  *
543  *	Claim the resource, and read the device cell ID if not already
544  *	initialized.  Register the AMBA device with the Linux device
545  *	manager.
546  */
amba_device_add(struct amba_device * dev,struct resource * parent)547 int amba_device_add(struct amba_device *dev, struct resource *parent)
548 {
549 	int ret;
550 
551 	ret = request_resource(parent, &dev->res);
552 	if (ret)
553 		return ret;
554 
555 	/* If primecell ID isn't hard-coded, figure it out */
556 	if (!dev->periphid) {
557 		/*
558 		 * AMBA device uevents require reading its pid and cid
559 		 * registers.  To do this, the device must be on, clocked and
560 		 * out of reset.  However in some cases those resources might
561 		 * not yet be available.  If that's the case, we suppress the
562 		 * generation of uevents until we can read the pid and cid
563 		 * registers.  See also amba_match().
564 		 */
565 		if (amba_read_periphid(dev))
566 			dev_set_uevent_suppress(&dev->dev, true);
567 	}
568 
569 	ret = device_add(&dev->dev);
570 	if (ret)
571 		release_resource(&dev->res);
572 
573 	return ret;
574 }
575 EXPORT_SYMBOL_GPL(amba_device_add);
576 
amba_device_initialize(struct amba_device * dev,const char * name)577 static void amba_device_initialize(struct amba_device *dev, const char *name)
578 {
579 	device_initialize(&dev->dev);
580 	if (name)
581 		dev_set_name(&dev->dev, "%s", name);
582 	dev->dev.release = amba_device_release;
583 	dev->dev.bus = &amba_bustype;
584 	dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
585 	dev->dev.dma_parms = &dev->dma_parms;
586 	dev->res.name = dev_name(&dev->dev);
587 	mutex_init(&dev->periphid_lock);
588 }
589 
590 /**
591  *	amba_device_alloc - allocate an AMBA device
592  *	@name: sysfs name of the AMBA device
593  *	@base: base of AMBA device
594  *	@size: size of AMBA device
595  *
596  *	Allocate and initialize an AMBA device structure.  Returns %NULL
597  *	on failure.
598  */
amba_device_alloc(const char * name,resource_size_t base,size_t size)599 struct amba_device *amba_device_alloc(const char *name, resource_size_t base,
600 	size_t size)
601 {
602 	struct amba_device *dev;
603 
604 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
605 	if (dev) {
606 		amba_device_initialize(dev, name);
607 		dev->res.start = base;
608 		dev->res.end = base + size - 1;
609 		dev->res.flags = IORESOURCE_MEM;
610 	}
611 
612 	return dev;
613 }
614 EXPORT_SYMBOL_GPL(amba_device_alloc);
615 
616 /**
617  *	amba_device_register - register an AMBA device
618  *	@dev: AMBA device to register
619  *	@parent: parent memory resource
620  *
621  *	Setup the AMBA device, reading the cell ID if present.
622  *	Claim the resource, and register the AMBA device with
623  *	the Linux device manager.
624  */
amba_device_register(struct amba_device * dev,struct resource * parent)625 int amba_device_register(struct amba_device *dev, struct resource *parent)
626 {
627 	amba_device_initialize(dev, dev->dev.init_name);
628 	dev->dev.init_name = NULL;
629 
630 	return amba_device_add(dev, parent);
631 }
632 EXPORT_SYMBOL(amba_device_register);
633 
634 /**
635  *	amba_device_put - put an AMBA device
636  *	@dev: AMBA device to put
637  */
amba_device_put(struct amba_device * dev)638 void amba_device_put(struct amba_device *dev)
639 {
640 	put_device(&dev->dev);
641 }
642 EXPORT_SYMBOL_GPL(amba_device_put);
643 
644 /**
645  *	amba_device_unregister - unregister an AMBA device
646  *	@dev: AMBA device to remove
647  *
648  *	Remove the specified AMBA device from the Linux device
649  *	manager.  All files associated with this object will be
650  *	destroyed, and device drivers notified that the device has
651  *	been removed.  The AMBA device's resources including
652  *	the amba_device structure will be freed once all
653  *	references to it have been dropped.
654  */
amba_device_unregister(struct amba_device * dev)655 void amba_device_unregister(struct amba_device *dev)
656 {
657 	device_unregister(&dev->dev);
658 }
659 EXPORT_SYMBOL(amba_device_unregister);
660 
661 /**
662  *	amba_request_regions - request all mem regions associated with device
663  *	@dev: amba_device structure for device
664  *	@name: name, or NULL to use driver name
665  */
amba_request_regions(struct amba_device * dev,const char * name)666 int amba_request_regions(struct amba_device *dev, const char *name)
667 {
668 	int ret = 0;
669 	u32 size;
670 
671 	if (!name)
672 		name = dev->dev.driver->name;
673 
674 	size = resource_size(&dev->res);
675 
676 	if (!request_mem_region(dev->res.start, size, name))
677 		ret = -EBUSY;
678 
679 	return ret;
680 }
681 EXPORT_SYMBOL(amba_request_regions);
682 
683 /**
684  *	amba_release_regions - release mem regions associated with device
685  *	@dev: amba_device structure for device
686  *
687  *	Release regions claimed by a successful call to amba_request_regions.
688  */
amba_release_regions(struct amba_device * dev)689 void amba_release_regions(struct amba_device *dev)
690 {
691 	u32 size;
692 
693 	size = resource_size(&dev->res);
694 	release_mem_region(dev->res.start, size);
695 }
696 EXPORT_SYMBOL(amba_release_regions);
697