aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/plat-omap/omap_device.c
blob: 2ed72013c2e22efb43fc78ce2764250a25919447 (plain) (blame)
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
/*
 * omap_device implementation
 *
 * Copyright (C) 2009 Nokia Corporation
 * Paul Walmsley
 *
 * Developed in collaboration with (alphabetical order): Benoit
 * Cousson, Kevin Hilman, Tony Lindgren, Rajendra Nayak, Vikram
 * Pandita, Sakari Poussa, Anand Sawant, Santosh Shilimkar, Richard
 * Woodruff
 *
 * 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.
 *
 * This code provides a consistent interface for OMAP device drivers
 * to control power management and interconnect properties of their
 * devices.
 *
 * In the medium- to long-term, this code should either be
 * a) implemented via arch-specific pointers in platform_data
 * or
 * b) implemented as a proper omap_bus/omap_device in Linux, no more
 *    platform_data func pointers
 *
 *
 * Guidelines for usage by driver authors:
 *
 * 1. These functions are intended to be used by device drivers via
 * function pointers in struct platform_data.  As an example,
 * omap_device_enable() should be passed to the driver as
 *
 * struct foo_driver_platform_data {
 * ...
 *      int (*device_enable)(struct platform_device *pdev);
 * ...
 * }
 *
 * Note that the generic "device_enable" name is used, rather than
 * "omap_device_enable".  This is so other architectures can pass in their
 * own enable/disable functions here.
 *
 * This should be populated during device setup:
 *
 * ...
 * pdata->device_enable = omap_device_enable;
 * ...
 *
 * 2. Drivers should first check to ensure the function pointer is not null
 * before calling it, as in:
 *
 * if (pdata->device_enable)
 *     pdata->device_enable(pdev);
 *
 * This allows other architectures that don't use similar device_enable()/
 * device_shutdown() functions to execute normally.
 *
 * ...
 *
 * Suggested usage by device drivers:
 *
 * During device initialization:
 * device_enable()
 *
 * During device idle:
 * (save remaining device context if necessary)
 * device_idle();
 *
 * During device resume:
 * device_enable();
 * (restore context if necessary)
 *
 * During device shutdown:
 * device_shutdown()
 * (device must be reinitialized at this point to use it again)
 *
 */
#undef DEBUG

#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/io.h>

#include <plat/omap_device.h>
#include <plat/omap_hwmod.h>

/* These parameters are passed to _omap_device_{de,}activate() */
#define USE_WAKEUP_LAT			0
#define IGNORE_WAKEUP_LAT		1


/* Private functions */

/**
 * _omap_device_activate - increase device readiness
 * @od: struct omap_device *
 * @ignore_lat: increase to latency target (0) or full readiness (1)?
 *
 * Increase readiness of omap_device @od (thus decreasing device
 * wakeup latency, but consuming more power).  If @ignore_lat is
 * IGNORE_WAKEUP_LAT, make the omap_device fully active.  Otherwise,
 * if @ignore_lat is USE_WAKEUP_LAT, and the device's maximum wakeup
 * latency is greater than the requested maximum wakeup latency, step
 * backwards in the omap_device_pm_latency table to ensure the
 * device's maximum wakeup latency is less than or equal to the
 * requested maximum wakeup latency.  Returns 0.
 */
static int _omap_device_activate(struct omap_device *od, u8 ignore_lat)
{
	struct timespec a, b, c;

	pr_debug("omap_device: %s: activating\n", od->pdev.name);

	while (od->pm_lat_level > 0) {
		struct omap_device_pm_latency *odpl;
		unsigned long long act_lat = 0;

		od->pm_lat_level--;

		odpl = od->pm_lats + od->pm_lat_level;

		if (!ignore_lat &&
		    (od->dev_wakeup_lat <= od->_dev_wakeup_lat_limit))
			break;

		read_persistent_clock(&a);

		/* XXX check return code */
		odpl->activate_func(od);

		read_persistent_clock(&b);

		c = timespec_sub(b, a);
		act_lat = timespec_to_ns(&c);

		pr_debug("omap_device: %s: pm_lat %d: activate: elapsed time "
			 "%llu nsec\n", od->pdev.name, od->pm_lat_level,
			 act_lat);

		WARN(act_lat > odpl->activate_lat, "omap_device: %s.%d: "
		     "activate step %d took longer than expected (%llu > %d)\n",
		     od->pdev.name, od->pdev.id, od->pm_lat_level,
		     act_lat, odpl->activate_lat);

		od->dev_wakeup_lat -= odpl->activate_lat;
	}

	return 0;
}

/**
 * _omap_device_deactivate - decrease device readiness
 * @od: struct omap_device *
 * @ignore_lat: decrease to latency target (0) or full inactivity (1)?
 *
 * Decrease readiness of omap_device @od (thus increasing device
 * wakeup latency, but conserving power).  If @ignore_lat is
 * IGNORE_WAKEUP_LAT, make the omap_device fully inactive.  Otherwise,
 * if @ignore_lat is USE_WAKEUP_LAT, and the device's maximum wakeup
 * latency is less than the requested maximum wakeup latency, step
 * forwards in the omap_device_pm_latency table to ensure the device's
 * maximum wakeup latency is less than or equal to the requested
 * maximum wakeup latency.  Returns 0.
 */
static int _omap_device_deactivate(struct omap_device *od, u8 ignore_lat)
{
	struct timespec a, b, c;

	pr_debug("omap_device: %s: deactivating\n", od->pdev.name);

	while (od->pm_lat_level < od->pm_lats_cnt) {
		struct omap_device_pm_latency *odpl;
		unsigned long long deact_lat = 0;

		odpl = od->pm_lats + od->pm_lat_level;

		if (!ignore_lat &&
		    ((od->dev_wakeup_lat + odpl->activate_lat) >
		     od->_dev_wakeup_lat_limit))
			break;

		read_persistent_clock(&a);

		/* XXX check return code */
		odpl->deactivate_func(od);

		read_persistent_clock(&b);

		c = timespec_sub(b, a);
		deact_lat = timespec_to_ns(&c);

		pr_debug("omap_device: %s: pm_lat %d: deactivate: elapsed time "
			 "%llu nsec\n", od->pdev.name, od->pm_lat_level,
			 deact_lat);

		WARN(deact_lat > odpl->deactivate_lat, "omap_device: %s.%d: "
		     "deactivate step %d took longer than expected "
		     "(%llu > %d)\n", od->pdev.name, od->pdev.id,
		     od->pm_lat_level, deact_lat, odpl->deactivate_lat);

		od->dev_wakeup_lat += odpl->activate_lat;

		od->pm_lat_level++;
	}

	return 0;
}

static inline struct omap_device *_find_by_pdev(struct platform_device *pdev)
{
	return container_of(pdev, struct omap_device, pdev);
}


/* Public functions for use by core code */

/**
 * omap_device_count_resources - count number of struct resource entries needed
 * @od: struct omap_device *
 *
 * Count the number of struct resource entries needed for this
 * omap_device @od.  Used by omap_device_build_ss() to determine how
 * much memory to allocate before calling
 * omap_device_fill_resources().  Returns the count.
 */
int omap_device_count_resources(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int c = 0;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		c += omap_hwmod_count_resources(oh);

	pr_debug("omap_device: %s: counted %d total resources across %d "
		 "hwmods\n", od->pdev.name, c, od->hwmods_cnt);

	return c;
}

/**
 * omap_device_fill_resources - fill in array of struct resource
 * @od: struct omap_device *
 * @res: pointer to an array of struct resource to be filled in
 *
 * Populate one or more empty struct resource pointed to by @res with
 * the resource data for this omap_device @od.  Used by
 * omap_device_build_ss() after calling omap_device_count_resources().
 * Ideally this function would not be needed at all.  If omap_device
 * replaces platform_device, then we can specify our own
 * get_resource()/ get_irq()/etc functions that use the underlying
 * omap_hwmod information.  Or if platform_device is extended to use
 * subarchitecture-specific function pointers, the various
 * platform_device functions can simply call omap_device internal
 * functions to get device resources.  Hacking around the existing
 * platform_device code wastes memory.  Returns 0.
 */
int omap_device_fill_resources(struct omap_device *od, struct resource *res)
{
	struct omap_hwmod *oh;
	int c = 0;
	int i, r;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++) {
		r = omap_hwmod_fill_resources(oh, res);
		res += r;
		c += r;
	}

	return 0;
}

/**
 * omap_device_build - build and register an omap_device with one omap_hwmod
 * @pdev_name: name of the platform_device driver to use
 * @pdev_id: this platform_device's connection ID
 * @oh: ptr to the single omap_hwmod that backs this omap_device
 * @pdata: platform_data ptr to associate with the platform_device
 * @pdata_len: amount of memory pointed to by @pdata
 * @pm_lats: pointer to a omap_device_pm_latency array for this device
 * @pm_lats_cnt: ARRAY_SIZE() of @pm_lats
 *
 * Convenience function for building and registering a single
 * omap_device record, which in turn builds and registers a
 * platform_device record.  See omap_device_build_ss() for more
 * information.  Returns ERR_PTR(-EINVAL) if @oh is NULL; otherwise,
 * passes along the return value of omap_device_build_ss().
 */
struct omap_device *omap_device_build(const char *pdev_name, int pdev_id,
				      struct omap_hwmod *oh, void *pdata,
				      int pdata_len,
				      struct omap_device_pm_latency *pm_lats,
				      int pm_lats_cnt)
{
	struct omap_hwmod *ohs[] = { oh };

	if (!oh)
		return ERR_PTR(-EINVAL);

	return omap_device_build_ss(pdev_name, pdev_id, ohs, 1, pdata,
				    pdata_len, pm_lats, pm_lats_cnt);
}

/**
 * omap_device_build_ss - build and register an omap_device with multiple hwmods
 * @pdev_name: name of the platform_device driver to use
 * @pdev_id: this platform_device's connection ID
 * @oh: ptr to the single omap_hwmod that backs this omap_device
 * @pdata: platform_data ptr to associate with the platform_device
 * @pdata_len: amount of memory pointed to by @pdata
 * @pm_lats: pointer to a omap_device_pm_latency array for this device
 * @pm_lats_cnt: ARRAY_SIZE() of @pm_lats
 *
 * Convenience function for building and registering an omap_device
 * subsystem record.  Subsystem records consist of multiple
 * omap_hwmods.  This function in turn builds and registers a
 * platform_device record.  Returns an ERR_PTR() on error, or passes
 * along the return value of omap_device_register().
 */
struct omap_device *omap_device_build_ss(const char *pdev_name, int pdev_id,
					 struct omap_hwmod **ohs, int oh_cnt,
					 void *pdata, int pdata_len,
					 struct omap_device_pm_latency *pm_lats,
					 int pm_lats_cnt)
{
	int ret = -ENOMEM;
	struct omap_device *od;
	char *pdev_name2;
	struct resource *res = NULL;
	int res_count;
	struct omap_hwmod **hwmods;

	if (!ohs || oh_cnt == 0 || !pdev_name)
		return ERR_PTR(-EINVAL);

	if (!pdata && pdata_len > 0)
		return ERR_PTR(-EINVAL);

	pr_debug("omap_device: %s: building with %d hwmods\n", pdev_name,
		 oh_cnt);

	od = kzalloc(sizeof(struct omap_device), GFP_KERNEL);
	if (!od)
		return ERR_PTR(-ENOMEM);

	od->hwmods_cnt = oh_cnt;

	hwmods = kzalloc(sizeof(struct omap_hwmod *) * oh_cnt,
			 GFP_KERNEL);
	if (!hwmods)
		goto odbs_exit1;

	memcpy(hwmods, ohs, sizeof(struct omap_hwmod *) * oh_cnt);
	od->hwmods = hwmods;

	pdev_name2 = kzalloc(strlen(pdev_name) + 1, GFP_KERNEL);
	if (!pdev_name2)
		goto odbs_exit2;
	strcpy(pdev_name2, pdev_name);

	od->pdev.name = pdev_name2;
	od->pdev.id = pdev_id;

	res_count = omap_device_count_resources(od);
	if (res_count > 0) {
		res = kzalloc(sizeof(struct resource) * res_count, GFP_KERNEL);
		if (!res)
			goto odbs_exit3;
	}
	omap_device_fill_resources(od, res);

	od->pdev.num_resources = res_count;
	od->pdev.resource = res;

	platform_device_add_data(&od->pdev, pdata, pdata_len);

	od->pm_lats = pm_lats;
	od->pm_lats_cnt = pm_lats_cnt;

	ret = omap_device_register(od);
	if (ret)
		goto odbs_exit4;

	return od;

odbs_exit4:
	kfree(res);
odbs_exit3:
	kfree(pdev_name2);
odbs_exit2:
	kfree(hwmods);
odbs_exit1:
	kfree(od);

	pr_err("omap_device: %s: build failed (%d)\n", pdev_name, ret);

	return ERR_PTR(ret);
}

/**
 * omap_device_register - register an omap_device with one omap_hwmod
 * @od: struct omap_device * to register
 *
 * Register the omap_device structure.  This currently just calls
 * platform_device_register() on the underlying platform_device.
 * Returns the return value of platform_device_register().
 */
int omap_device_register(struct omap_device *od)
{
	pr_debug("omap_device: %s: registering\n", od->pdev.name);

	return platform_device_register(&od->pdev);
}


/* Public functions for use by device drivers through struct platform_data */

/**
 * omap_device_enable - fully activate an omap_device
 * @od: struct omap_device * to activate
 *
 * Do whatever is necessary for the hwmods underlying omap_device @od
 * to be accessible and ready to operate.  This generally involves
 * enabling clocks, setting SYSCONFIG registers; and in the future may
 * involve remuxing pins.  Device drivers should call this function
 * (through platform_data function pointers) where they would normally
 * enable clocks, etc.  Returns -EINVAL if called when the omap_device
 * is already enabled, or passes along the return value of
 * _omap_device_activate().
 */
int omap_device_enable(struct platform_device *pdev)
{
	int ret;
	struct omap_device *od;

	od = _find_by_pdev(pdev);

	if (od->_state == OMAP_DEVICE_STATE_ENABLED) {
		WARN(1, "omap_device: %s.%d: omap_device_enable() called from "
		     "invalid state\n", od->pdev.name, od->pdev.id);
		return -EINVAL;
	}

	/* Enable everything if we're enabling this device from scratch */
	if (od->_state == OMAP_DEVICE_STATE_UNKNOWN)
		od->pm_lat_level = od->pm_lats_cnt;

	ret = _omap_device_activate(od, IGNORE_WAKEUP_LAT);

	od->dev_wakeup_lat = 0;
	od->_dev_wakeup_lat_limit = UINT_MAX;
	od->_state = OMAP_DEVICE_STATE_ENABLED;

	return ret;
}

/**
 * omap_device_idle - idle an omap_device
 * @od: struct omap_device * to idle
 *
 * Idle omap_device @od by calling as many .deactivate_func() entries
 * in the omap_device's pm_lats table as is possible without exceeding
 * the device's maximum wakeup latency limit, pm_lat_limit.  Device
 * drivers should call this function (through platform_data function
 * pointers) where they would normally disable clocks after operations
 * complete, etc..  Returns -EINVAL if the omap_device is not
 * currently enabled, or passes along the return value of
 * _omap_device_deactivate().
 */
int omap_device_idle(struct platform_device *pdev)
{
	int ret;
	struct omap_device *od;

	od = _find_by_pdev(pdev);

	if (od->_state != OMAP_DEVICE_STATE_ENABLED) {
		WARN(1, "omap_device: %s.%d: omap_device_idle() called from "
		     "invalid state\n", od->pdev.name, od->pdev.id);
		return -EINVAL;
	}

	ret = _omap_device_deactivate(od, USE_WAKEUP_LAT);

	od->_state = OMAP_DEVICE_STATE_IDLE;

	return ret;
}

/**
 * omap_device_shutdown - shut down an omap_device
 * @od: struct omap_device * to shut down
 *
 * Shut down omap_device @od by calling all .deactivate_func() entries
 * in the omap_device's pm_lats table and then shutting down all of
 * the underlying omap_hwmods.  Used when a device is being "removed"
 * or a device driver is being unloaded.  Returns -EINVAL if the
 * omap_device is not currently enabled or idle, or passes along the
 * return value of _omap_device_deactivate().
 */
int omap_device_shutdown(struct platform_device *pdev)
{
	int ret, i;
	struct omap_device *od;
	struct omap_hwmod *oh;

	od = _find_by_pdev(pdev);

	if (od->_state != OMAP_DEVICE_STATE_ENABLED &&
	    od->_state != OMAP_DEVICE_STATE_IDLE) {
		WARN(1, "omap_device: %s.%d: omap_device_shutdown() called "
		     "from invalid state\n", od->pdev.name, od->pdev.id);
		return -EINVAL;
	}

	ret = _omap_device_deactivate(od, IGNORE_WAKEUP_LAT);

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_shutdown(oh);

	od->_state = OMAP_DEVICE_STATE_SHUTDOWN;

	return ret;
}

/**
 * omap_device_align_pm_lat - activate/deactivate device to match wakeup lat lim
 * @od: struct omap_device *
 *
 * When a device's maximum wakeup latency limit changes, call some of
 * the .activate_func or .deactivate_func function pointers in the
 * omap_device's pm_lats array to ensure that the device's maximum
 * wakeup latency is less than or equal to the new latency limit.
 * Intended to be called by OMAP PM code whenever a device's maximum
 * wakeup latency limit changes (e.g., via
 * omap_pm_set_dev_wakeup_lat()).  Returns 0 if nothing needs to be
 * done (e.g., if the omap_device is not currently idle, or if the
 * wakeup latency is already current with the new limit) or passes
 * along the return value of _omap_device_deactivate() or
 * _omap_device_activate().
 */
int omap_device_align_pm_lat(struct platform_device *pdev,
			     u32 new_wakeup_lat_limit)
{
	int ret = -EINVAL;
	struct omap_device *od;

	od = _find_by_pdev(pdev);

	if (new_wakeup_lat_limit == od->dev_wakeup_lat)
		return 0;

	od->_dev_wakeup_lat_limit = new_wakeup_lat_limit;

	if (od->_state != OMAP_DEVICE_STATE_IDLE)
		return 0;
	else if (new_wakeup_lat_limit > od->dev_wakeup_lat)
		ret = _omap_device_deactivate(od, USE_WAKEUP_LAT);
	else if (new_wakeup_lat_limit < od->dev_wakeup_lat)
		ret = _omap_device_activate(od, USE_WAKEUP_LAT);

	return ret;
}

/**
 * omap_device_get_pwrdm - return the powerdomain * associated with @od
 * @od: struct omap_device *
 *
 * Return the powerdomain associated with the first underlying
 * omap_hwmod for this omap_device.  Intended for use by core OMAP PM
 * code.  Returns NULL on error or a struct powerdomain * upon
 * success.
 */
struct powerdomain *omap_device_get_pwrdm(struct omap_device *od)
{
	/*
	 * XXX Assumes that all omap_hwmod powerdomains are identical.
	 * This may not necessarily be true.  There should be a sanity
	 * check in here to WARN() if any difference appears.
	 */
	if (!od->hwmods_cnt)
		return NULL;

	return omap_hwmod_get_pwrdm(od->hwmods[0]);
}

/*
 * Public functions intended for use in omap_device_pm_latency
 * .activate_func and .deactivate_func function pointers
 */

/**
 * omap_device_enable_hwmods - call omap_hwmod_enable() on all hwmods
 * @od: struct omap_device *od
 *
 * Enable all underlying hwmods.  Returns 0.
 */
int omap_device_enable_hwmods(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_enable(oh);

	/* XXX pass along return value here? */
	return 0;
}

/**
 * omap_device_idle_hwmods - call omap_hwmod_idle() on all hwmods
 * @od: struct omap_device *od
 *
 * Idle all underlying hwmods.  Returns 0.
 */
int omap_device_idle_hwmods(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_idle(oh);

	/* XXX pass along return value here? */
	return 0;
}

/**
 * omap_device_disable_clocks - disable all main and interface clocks
 * @od: struct omap_device *od
 *
 * Disable the main functional clock and interface clock for all of the
 * omap_hwmods associated with the omap_device.  Returns 0.
 */
int omap_device_disable_clocks(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_disable_clocks(oh);

	/* XXX pass along return value here? */
	return 0;
}

/**
 * omap_device_enable_clocks - enable all main and interface clocks
 * @od: struct omap_device *od
 *
 * Enable the main functional clock and interface clock for all of the
 * omap_hwmods associated with the omap_device.  Returns 0.
 */
int omap_device_enable_clocks(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_enable_clocks(oh);

	/* XXX pass along return value here? */
	return 0;
}