summaryrefslogtreecommitdiffstats
path: root/arch/arm/mach-tegra/clock.c
blob: 8dad8d18cb49cd26e12212718de9295a4f4e550a (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
/*
 *
 * Copyright (C) 2010 Google, Inc.
 *
 * Author:
 *	Colin Cross <ccross@google.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include <mach/clk.h>

#include "board.h"
#include "clock.h"

/*
 * Locking:
 *
 * Each struct clk has a spinlock.
 *
 * To avoid AB-BA locking problems, locks must always be traversed from child
 * clock to parent clock.  For example, when enabling a clock, the clock's lock
 * is taken, and then clk_enable is called on the parent, which take's the
 * parent clock's lock.  There is one exceptions to this ordering: When dumping
 * the clock tree through debugfs.  In this case, clk_lock_all is called,
 * which attemps to iterate through the entire list of clocks and take every
 * clock lock.  If any call to spin_trylock fails, all locked clocks are
 * unlocked, and the process is retried.  When all the locks are held,
 * the only clock operation that can be called is clk_get_rate_all_locked.
 *
 * Within a single clock, no clock operation can call another clock operation
 * on itself, except for clk_get_rate_locked and clk_set_rate_locked.  Any
 * clock operation can call any other clock operation on any of it's possible
 * parents.
 *
 * An additional mutex, clock_list_lock, is used to protect the list of all
 * clocks.
 *
 * The clock operations must lock internally to protect against
 * read-modify-write on registers that are shared by multiple clocks
 */
static DEFINE_MUTEX(clock_list_lock);
static LIST_HEAD(clocks);

struct clk *tegra_get_clock_by_name(const char *name)
{
	struct clk *c;
	struct clk *ret = NULL;
	mutex_lock(&clock_list_lock);
	list_for_each_entry(c, &clocks, node) {
		if (strcmp(c->name, name) == 0) {
			ret = c;
			break;
		}
	}
	mutex_unlock(&clock_list_lock);
	return ret;
}

/* Must be called with c->spinlock held */
static unsigned long clk_predict_rate_from_parent(struct clk *c, struct clk *p)
{
	u64 rate;

	rate = clk_get_rate(p);

	if (c->mul != 0 && c->div != 0) {
		rate *= c->mul;
		rate += c->div - 1; /* round up */
		do_div(rate, c->div);
	}

	return rate;
}

/* Must be called with c->spinlock held */
unsigned long clk_get_rate_locked(struct clk *c)
{
	unsigned long rate;

	if (c->parent)
		rate = clk_predict_rate_from_parent(c, c->parent);
	else
		rate = c->rate;

	return rate;
}

unsigned long clk_get_rate(struct clk *c)
{
	unsigned long flags;
	unsigned long rate;

	spin_lock_irqsave(&c->spinlock, flags);

	rate = clk_get_rate_locked(c);

	spin_unlock_irqrestore(&c->spinlock, flags);

	return rate;
}
EXPORT_SYMBOL(clk_get_rate);

int clk_reparent(struct clk *c, struct clk *parent)
{
	c->parent = parent;
	return 0;
}

void clk_init(struct clk *c)
{
	spin_lock_init(&c->spinlock);

	if (c->ops && c->ops->init)
		c->ops->init(c);

	if (!c->ops || !c->ops->enable) {
		c->refcnt++;
		c->set = true;
		if (c->parent)
			c->state = c->parent->state;
		else
			c->state = ON;
	}

	mutex_lock(&clock_list_lock);
	list_add(&c->node, &clocks);
	mutex_unlock(&clock_list_lock);
}

int clk_enable(struct clk *c)
{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&c->spinlock, flags);

	if (c->refcnt == 0) {
		if (c->parent) {
			ret = clk_enable(c->parent);
			if (ret)
				goto out;
		}

		if (c->ops && c->ops->enable) {
			ret = c->ops->enable(c);
			if (ret) {
				if (c->parent)
					clk_disable(c->parent);
				goto out;
			}
			c->state = ON;
			c->set = true;
		}
	}
	c->refcnt++;
out:
	spin_unlock_irqrestore(&c->spinlock, flags);
	return ret;
}
EXPORT_SYMBOL(clk_enable);

void clk_disable(struct clk *c)
{
	unsigned long flags;

	spin_lock_irqsave(&c->spinlock, flags);

	if (c->refcnt == 0) {
		WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
		spin_unlock_irqrestore(&c->spinlock, flags);
		return;
	}
	if (c->refcnt == 1) {
		if (c->ops && c->ops->disable)
			c->ops->disable(c);

		if (c->parent)
			clk_disable(c->parent);

		c->state = OFF;
	}
	c->refcnt--;

	spin_unlock_irqrestore(&c->spinlock, flags);
}
EXPORT_SYMBOL(clk_disable);

int clk_set_parent(struct clk *c, struct clk *parent)
{
	int ret;
	unsigned long flags;
	unsigned long new_rate;
	unsigned long old_rate;

	spin_lock_irqsave(&c->spinlock, flags);

	if (!c->ops || !c->ops->set_parent) {
		ret = -ENOSYS;
		goto out;
	}

	new_rate = clk_predict_rate_from_parent(c, parent);
	old_rate = clk_get_rate_locked(c);

	ret = c->ops->set_parent(c, parent);
	if (ret)
		goto out;

out:
	spin_unlock_irqrestore(&c->spinlock, flags);
	return ret;
}
EXPORT_SYMBOL(clk_set_parent);

struct clk *clk_get_parent(struct clk *c)
{
	return c->parent;
}
EXPORT_SYMBOL(clk_get_parent);

int clk_set_rate_locked(struct clk *c, unsigned long rate)
{
	long new_rate;

	if (!c->ops || !c->ops->set_rate)
		return -ENOSYS;

	if (rate > c->max_rate)
		rate = c->max_rate;

	if (c->ops && c->ops->round_rate) {
		new_rate = c->ops->round_rate(c, rate);

		if (new_rate < 0)
			return new_rate;

		rate = new_rate;
	}

	return c->ops->set_rate(c, rate);
}

int clk_set_rate(struct clk *c, unsigned long rate)
{
	int ret;
	unsigned long flags;

	spin_lock_irqsave(&c->spinlock, flags);

	ret = clk_set_rate_locked(c, rate);

	spin_unlock_irqrestore(&c->spinlock, flags);

	return ret;
}
EXPORT_SYMBOL(clk_set_rate);


/* Must be called with clocks lock and all indvidual clock locks held */
unsigned long clk_get_rate_all_locked(struct clk *c)
{
	u64 rate;
	int mul = 1;
	int div = 1;
	struct clk *p = c;

	while (p) {
		c = p;
		if (c->mul != 0 && c->div != 0) {
			mul *= c->mul;
			div *= c->div;
		}
		p = c->parent;
	}

	rate = c->rate;
	rate *= mul;
	do_div(rate, div);

	return rate;
}

long clk_round_rate(struct clk *c, unsigned long rate)
{
	unsigned long flags;
	long ret;

	spin_lock_irqsave(&c->spinlock, flags);

	if (!c->ops || !c->ops->round_rate) {
		ret = -ENOSYS;
		goto out;
	}

	if (rate > c->max_rate)
		rate = c->max_rate;

	ret = c->ops->round_rate(c, rate);

out:
	spin_unlock_irqrestore(&c->spinlock, flags);
	return ret;
}
EXPORT_SYMBOL(clk_round_rate);

static int tegra_clk_init_one_from_table(struct tegra_clk_init_table *table)
{
	struct clk *c;
	struct clk *p;

	int ret = 0;

	c = tegra_get_clock_by_name(table->name);

	if (!c) {
		pr_warning("Unable to initialize clock %s\n",
			table->name);
		return -ENODEV;
	}

	if (table->parent) {
		p = tegra_get_clock_by_name(table->parent);
		if (!p) {
			pr_warning("Unable to find parent %s of clock %s\n",
				table->parent, table->name);
			return -ENODEV;
		}

		if (c->parent != p) {
			ret = clk_set_parent(c, p);
			if (ret) {
				pr_warning("Unable to set parent %s of clock %s: %d\n",
					table->parent, table->name, ret);
				return -EINVAL;
			}
		}
	}

	if (table->rate && table->rate != clk_get_rate(c)) {
		ret = clk_set_rate(c, table->rate);
		if (ret) {
			pr_warning("Unable to set clock %s to rate %lu: %d\n",
				table->name, table->rate, ret);
			return -EINVAL;
		}
	}

	if (table->enabled) {
		ret = clk_enable(c);
		if (ret) {
			pr_warning("Unable to enable clock %s: %d\n",
				table->name, ret);
			return -EINVAL;
		}
	}

	return 0;
}

void tegra_clk_init_from_table(struct tegra_clk_init_table *table)
{
	for (; table->name; table++)
		tegra_clk_init_one_from_table(table);
}
EXPORT_SYMBOL(tegra_clk_init_from_table);

void tegra_periph_reset_deassert(struct clk *c)
{
	BUG_ON(!c->ops->reset);
	c->ops->reset(c, false);
}
EXPORT_SYMBOL(tegra_periph_reset_deassert);

void tegra_periph_reset_assert(struct clk *c)
{
	BUG_ON(!c->ops->reset);
	c->ops->reset(c, true);
}
EXPORT_SYMBOL(tegra_periph_reset_assert);

/* Several extended clock configuration bits (e.g., clock routing, clock
 * phase control) are included in PLL and peripheral clock source
 * registers. */
int tegra_clk_cfg_ex(struct clk *c, enum tegra_clk_ex_param p, u32 setting)
{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&c->spinlock, flags);

	if (!c->ops || !c->ops->clk_cfg_ex) {
		ret = -ENOSYS;
		goto out;
	}
	ret = c->ops->clk_cfg_ex(c, p, setting);

out:
	spin_unlock_irqrestore(&c->spinlock, flags);

	return ret;
}

#ifdef CONFIG_DEBUG_FS

static int __clk_lock_all_spinlocks(void)
{
	struct clk *c;

	list_for_each_entry(c, &clocks, node)
		if (!spin_trylock(&c->spinlock))
			goto unlock_spinlocks;

	return 0;

unlock_spinlocks:
	list_for_each_entry_continue_reverse(c, &clocks, node)
		spin_unlock(&c->spinlock);

	return -EAGAIN;
}

static void __clk_unlock_all_spinlocks(void)
{
	struct clk *c;

	list_for_each_entry_reverse(c, &clocks, node)
		spin_unlock(&c->spinlock);
}

/*
 * This function retries until it can take all locks, and may take
 * an arbitrarily long time to complete.
 * Must be called with irqs enabled, returns with irqs disabled
 * Must be called with clock_list_lock held
 */
static void clk_lock_all(void)
{
	int ret;
retry:
	local_irq_disable();

	ret = __clk_lock_all_spinlocks();
	if (ret)
		goto failed_spinlocks;

	/* All locks taken successfully, return */
	return;

failed_spinlocks:
	local_irq_enable();
	yield();
	goto retry;
}

/*
 * Unlocks all clocks after a clk_lock_all
 * Must be called with irqs disabled, returns with irqs enabled
 * Must be called with clock_list_lock held
 */
static void clk_unlock_all(void)
{
	__clk_unlock_all_spinlocks();

	local_irq_enable();
}

static struct dentry *clk_debugfs_root;


static void clock_tree_show_one(struct seq_file *s, struct clk *c, int level)
{
	struct clk *child;
	const char *state = "uninit";
	char div[8] = {0};

	if (c->state == ON)
		state = "on";
	else if (c->state == OFF)
		state = "off";

	if (c->mul != 0 && c->div != 0) {
		if (c->mul > c->div) {
			int mul = c->mul / c->div;
			int mul2 = (c->mul * 10 / c->div) % 10;
			int mul3 = (c->mul * 10) % c->div;
			if (mul2 == 0 && mul3 == 0)
				snprintf(div, sizeof(div), "x%d", mul);
			else if (mul3 == 0)
				snprintf(div, sizeof(div), "x%d.%d", mul, mul2);
			else
				snprintf(div, sizeof(div), "x%d.%d..", mul, mul2);
		} else {
			snprintf(div, sizeof(div), "%d%s", c->div / c->mul,
				(c->div % c->mul) ? ".5" : "");
		}
	}

	seq_printf(s, "%*s%c%c%-*s %-6s %-3d %-8s %-10lu\n",
		level * 3 + 1, "",
		c->rate > c->max_rate ? '!' : ' ',
		!c->set ? '*' : ' ',
		30 - level * 3, c->name,
		state, c->refcnt, div, clk_get_rate_all_locked(c));

	list_for_each_entry(child, &clocks, node) {
		if (child->parent != c)
			continue;

		clock_tree_show_one(s, child, level + 1);
	}
}

static int clock_tree_show(struct seq_file *s, void *data)
{
	struct clk *c;
	seq_printf(s, "   clock                          state  ref div      rate\n");
	seq_printf(s, "--------------------------------------------------------------\n");

	mutex_lock(&clock_list_lock);

	clk_lock_all();

	list_for_each_entry(c, &clocks, node)
		if (c->parent == NULL)
			clock_tree_show_one(s, c, 0);

	clk_unlock_all();

	mutex_unlock(&clock_list_lock);
	return 0;
}

static int clock_tree_open(struct inode *inode, struct file *file)
{
	return single_open(file, clock_tree_show, inode->i_private);
}

static const struct file_operations clock_tree_fops = {
	.open		= clock_tree_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int possible_parents_show(struct seq_file *s, void *data)
{
	struct clk *c = s->private;
	int i;

	for (i = 0; c->inputs[i].input; i++) {
		char *first = (i == 0) ? "" : " ";
		seq_printf(s, "%s%s", first, c->inputs[i].input->name);
	}
	seq_printf(s, "\n");
	return 0;
}

static int possible_parents_open(struct inode *inode, struct file *file)
{
	return single_open(file, possible_parents_show, inode->i_private);
}

static const struct file_operations possible_parents_fops = {
	.open		= possible_parents_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int clk_debugfs_register_one(struct clk *c)
{
	struct dentry *d;

	d = debugfs_create_dir(c->name, clk_debugfs_root);
	if (!d)
		return -ENOMEM;
	c->dent = d;

	d = debugfs_create_u8("refcnt", S_IRUGO, c->dent, (u8 *)&c->refcnt);
	if (!d)
		goto err_out;

	d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
	if (!d)
		goto err_out;

	d = debugfs_create_x32("flags", S_IRUGO, c->dent, (u32 *)&c->flags);
	if (!d)
		goto err_out;

	if (c->inputs) {
		d = debugfs_create_file("possible_parents", S_IRUGO, c->dent,
			c, &possible_parents_fops);
		if (!d)
			goto err_out;
	}

	return 0;

err_out:
	debugfs_remove_recursive(c->dent);
	return -ENOMEM;
}

static int clk_debugfs_register(struct clk *c)
{
	int err;
	struct clk *pa = c->parent;

	if (pa && !pa->dent) {
		err = clk_debugfs_register(pa);
		if (err)
			return err;
	}

	if (!c->dent) {
		err = clk_debugfs_register_one(c);
		if (err)
			return err;
	}
	return 0;
}

static int __init clk_debugfs_init(void)
{
	struct clk *c;
	struct dentry *d;
	int err = -ENOMEM;

	d = debugfs_create_dir("clock", NULL);
	if (!d)
		return -ENOMEM;
	clk_debugfs_root = d;

	d = debugfs_create_file("clock_tree", S_IRUGO, clk_debugfs_root, NULL,
		&clock_tree_fops);
	if (!d)
		goto err_out;

	list_for_each_entry(c, &clocks, node) {
		err = clk_debugfs_register(c);
		if (err)
			goto err_out;
	}
	return 0;
err_out:
	debugfs_remove_recursive(clk_debugfs_root);
	return err;
}

late_initcall(clk_debugfs_init);
#endif
OpenPOWER on IntegriCloud