xref: /openbmc/linux/drivers/clk/clk.c (revision 6774def6)
1 /*
2  * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
3  * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  *
9  * Standard functionality for the common clock API.  See Documentation/clk.txt
10  */
11 
12 #include <linux/clk-private.h>
13 #include <linux/clk/clk-conf.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <linux/spinlock.h>
17 #include <linux/err.h>
18 #include <linux/list.h>
19 #include <linux/slab.h>
20 #include <linux/of.h>
21 #include <linux/device.h>
22 #include <linux/init.h>
23 #include <linux/sched.h>
24 
25 #include "clk.h"
26 
27 static DEFINE_SPINLOCK(enable_lock);
28 static DEFINE_MUTEX(prepare_lock);
29 
30 static struct task_struct *prepare_owner;
31 static struct task_struct *enable_owner;
32 
33 static int prepare_refcnt;
34 static int enable_refcnt;
35 
36 static HLIST_HEAD(clk_root_list);
37 static HLIST_HEAD(clk_orphan_list);
38 static LIST_HEAD(clk_notifier_list);
39 
40 /***           locking             ***/
41 static void clk_prepare_lock(void)
42 {
43 	if (!mutex_trylock(&prepare_lock)) {
44 		if (prepare_owner == current) {
45 			prepare_refcnt++;
46 			return;
47 		}
48 		mutex_lock(&prepare_lock);
49 	}
50 	WARN_ON_ONCE(prepare_owner != NULL);
51 	WARN_ON_ONCE(prepare_refcnt != 0);
52 	prepare_owner = current;
53 	prepare_refcnt = 1;
54 }
55 
56 static void clk_prepare_unlock(void)
57 {
58 	WARN_ON_ONCE(prepare_owner != current);
59 	WARN_ON_ONCE(prepare_refcnt == 0);
60 
61 	if (--prepare_refcnt)
62 		return;
63 	prepare_owner = NULL;
64 	mutex_unlock(&prepare_lock);
65 }
66 
67 static unsigned long clk_enable_lock(void)
68 {
69 	unsigned long flags;
70 
71 	if (!spin_trylock_irqsave(&enable_lock, flags)) {
72 		if (enable_owner == current) {
73 			enable_refcnt++;
74 			return flags;
75 		}
76 		spin_lock_irqsave(&enable_lock, flags);
77 	}
78 	WARN_ON_ONCE(enable_owner != NULL);
79 	WARN_ON_ONCE(enable_refcnt != 0);
80 	enable_owner = current;
81 	enable_refcnt = 1;
82 	return flags;
83 }
84 
85 static void clk_enable_unlock(unsigned long flags)
86 {
87 	WARN_ON_ONCE(enable_owner != current);
88 	WARN_ON_ONCE(enable_refcnt == 0);
89 
90 	if (--enable_refcnt)
91 		return;
92 	enable_owner = NULL;
93 	spin_unlock_irqrestore(&enable_lock, flags);
94 }
95 
96 /***        debugfs support        ***/
97 
98 #ifdef CONFIG_DEBUG_FS
99 #include <linux/debugfs.h>
100 
101 static struct dentry *rootdir;
102 static int inited = 0;
103 static DEFINE_MUTEX(clk_debug_lock);
104 static HLIST_HEAD(clk_debug_list);
105 
106 static struct hlist_head *all_lists[] = {
107 	&clk_root_list,
108 	&clk_orphan_list,
109 	NULL,
110 };
111 
112 static struct hlist_head *orphan_list[] = {
113 	&clk_orphan_list,
114 	NULL,
115 };
116 
117 static void clk_summary_show_one(struct seq_file *s, struct clk *c, int level)
118 {
119 	if (!c)
120 		return;
121 
122 	seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n",
123 		   level * 3 + 1, "",
124 		   30 - level * 3, c->name,
125 		   c->enable_count, c->prepare_count, clk_get_rate(c),
126 		   clk_get_accuracy(c), clk_get_phase(c));
127 }
128 
129 static void clk_summary_show_subtree(struct seq_file *s, struct clk *c,
130 				     int level)
131 {
132 	struct clk *child;
133 
134 	if (!c)
135 		return;
136 
137 	clk_summary_show_one(s, c, level);
138 
139 	hlist_for_each_entry(child, &c->children, child_node)
140 		clk_summary_show_subtree(s, child, level + 1);
141 }
142 
143 static int clk_summary_show(struct seq_file *s, void *data)
144 {
145 	struct clk *c;
146 	struct hlist_head **lists = (struct hlist_head **)s->private;
147 
148 	seq_puts(s, "   clock                         enable_cnt  prepare_cnt        rate   accuracy   phase\n");
149 	seq_puts(s, "----------------------------------------------------------------------------------------\n");
150 
151 	clk_prepare_lock();
152 
153 	for (; *lists; lists++)
154 		hlist_for_each_entry(c, *lists, child_node)
155 			clk_summary_show_subtree(s, c, 0);
156 
157 	clk_prepare_unlock();
158 
159 	return 0;
160 }
161 
162 
163 static int clk_summary_open(struct inode *inode, struct file *file)
164 {
165 	return single_open(file, clk_summary_show, inode->i_private);
166 }
167 
168 static const struct file_operations clk_summary_fops = {
169 	.open		= clk_summary_open,
170 	.read		= seq_read,
171 	.llseek		= seq_lseek,
172 	.release	= single_release,
173 };
174 
175 static void clk_dump_one(struct seq_file *s, struct clk *c, int level)
176 {
177 	if (!c)
178 		return;
179 
180 	seq_printf(s, "\"%s\": { ", c->name);
181 	seq_printf(s, "\"enable_count\": %d,", c->enable_count);
182 	seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);
183 	seq_printf(s, "\"rate\": %lu", clk_get_rate(c));
184 	seq_printf(s, "\"accuracy\": %lu", clk_get_accuracy(c));
185 	seq_printf(s, "\"phase\": %d", clk_get_phase(c));
186 }
187 
188 static void clk_dump_subtree(struct seq_file *s, struct clk *c, int level)
189 {
190 	struct clk *child;
191 
192 	if (!c)
193 		return;
194 
195 	clk_dump_one(s, c, level);
196 
197 	hlist_for_each_entry(child, &c->children, child_node) {
198 		seq_printf(s, ",");
199 		clk_dump_subtree(s, child, level + 1);
200 	}
201 
202 	seq_printf(s, "}");
203 }
204 
205 static int clk_dump(struct seq_file *s, void *data)
206 {
207 	struct clk *c;
208 	bool first_node = true;
209 	struct hlist_head **lists = (struct hlist_head **)s->private;
210 
211 	seq_printf(s, "{");
212 
213 	clk_prepare_lock();
214 
215 	for (; *lists; lists++) {
216 		hlist_for_each_entry(c, *lists, child_node) {
217 			if (!first_node)
218 				seq_puts(s, ",");
219 			first_node = false;
220 			clk_dump_subtree(s, c, 0);
221 		}
222 	}
223 
224 	clk_prepare_unlock();
225 
226 	seq_printf(s, "}");
227 	return 0;
228 }
229 
230 
231 static int clk_dump_open(struct inode *inode, struct file *file)
232 {
233 	return single_open(file, clk_dump, inode->i_private);
234 }
235 
236 static const struct file_operations clk_dump_fops = {
237 	.open		= clk_dump_open,
238 	.read		= seq_read,
239 	.llseek		= seq_lseek,
240 	.release	= single_release,
241 };
242 
243 /* caller must hold prepare_lock */
244 static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
245 {
246 	struct dentry *d;
247 	int ret = -ENOMEM;
248 
249 	if (!clk || !pdentry) {
250 		ret = -EINVAL;
251 		goto out;
252 	}
253 
254 	d = debugfs_create_dir(clk->name, pdentry);
255 	if (!d)
256 		goto out;
257 
258 	clk->dentry = d;
259 
260 	d = debugfs_create_u32("clk_rate", S_IRUGO, clk->dentry,
261 			(u32 *)&clk->rate);
262 	if (!d)
263 		goto err_out;
264 
265 	d = debugfs_create_u32("clk_accuracy", S_IRUGO, clk->dentry,
266 			(u32 *)&clk->accuracy);
267 	if (!d)
268 		goto err_out;
269 
270 	d = debugfs_create_u32("clk_phase", S_IRUGO, clk->dentry,
271 			(u32 *)&clk->phase);
272 	if (!d)
273 		goto err_out;
274 
275 	d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry,
276 			(u32 *)&clk->flags);
277 	if (!d)
278 		goto err_out;
279 
280 	d = debugfs_create_u32("clk_prepare_count", S_IRUGO, clk->dentry,
281 			(u32 *)&clk->prepare_count);
282 	if (!d)
283 		goto err_out;
284 
285 	d = debugfs_create_u32("clk_enable_count", S_IRUGO, clk->dentry,
286 			(u32 *)&clk->enable_count);
287 	if (!d)
288 		goto err_out;
289 
290 	d = debugfs_create_u32("clk_notifier_count", S_IRUGO, clk->dentry,
291 			(u32 *)&clk->notifier_count);
292 	if (!d)
293 		goto err_out;
294 
295 	if (clk->ops->debug_init) {
296 		ret = clk->ops->debug_init(clk->hw, clk->dentry);
297 		if (ret)
298 			goto err_out;
299 	}
300 
301 	ret = 0;
302 	goto out;
303 
304 err_out:
305 	debugfs_remove_recursive(clk->dentry);
306 	clk->dentry = NULL;
307 out:
308 	return ret;
309 }
310 
311 /**
312  * clk_debug_register - add a clk node to the debugfs clk tree
313  * @clk: the clk being added to the debugfs clk tree
314  *
315  * Dynamically adds a clk to the debugfs clk tree if debugfs has been
316  * initialized.  Otherwise it bails out early since the debugfs clk tree
317  * will be created lazily by clk_debug_init as part of a late_initcall.
318  */
319 static int clk_debug_register(struct clk *clk)
320 {
321 	int ret = 0;
322 
323 	mutex_lock(&clk_debug_lock);
324 	hlist_add_head(&clk->debug_node, &clk_debug_list);
325 
326 	if (!inited)
327 		goto unlock;
328 
329 	ret = clk_debug_create_one(clk, rootdir);
330 unlock:
331 	mutex_unlock(&clk_debug_lock);
332 
333 	return ret;
334 }
335 
336  /**
337  * clk_debug_unregister - remove a clk node from the debugfs clk tree
338  * @clk: the clk being removed from the debugfs clk tree
339  *
340  * Dynamically removes a clk and all it's children clk nodes from the
341  * debugfs clk tree if clk->dentry points to debugfs created by
342  * clk_debug_register in __clk_init.
343  */
344 static void clk_debug_unregister(struct clk *clk)
345 {
346 	mutex_lock(&clk_debug_lock);
347 	if (!clk->dentry)
348 		goto out;
349 
350 	hlist_del_init(&clk->debug_node);
351 	debugfs_remove_recursive(clk->dentry);
352 	clk->dentry = NULL;
353 out:
354 	mutex_unlock(&clk_debug_lock);
355 }
356 
357 struct dentry *clk_debugfs_add_file(struct clk *clk, char *name, umode_t mode,
358 				void *data, const struct file_operations *fops)
359 {
360 	struct dentry *d = NULL;
361 
362 	if (clk->dentry)
363 		d = debugfs_create_file(name, mode, clk->dentry, data, fops);
364 
365 	return d;
366 }
367 EXPORT_SYMBOL_GPL(clk_debugfs_add_file);
368 
369 /**
370  * clk_debug_init - lazily create the debugfs clk tree visualization
371  *
372  * clks are often initialized very early during boot before memory can
373  * be dynamically allocated and well before debugfs is setup.
374  * clk_debug_init walks the clk tree hierarchy while holding
375  * prepare_lock and creates the topology as part of a late_initcall,
376  * thus insuring that clks initialized very early will still be
377  * represented in the debugfs clk tree.  This function should only be
378  * called once at boot-time, and all other clks added dynamically will
379  * be done so with clk_debug_register.
380  */
381 static int __init clk_debug_init(void)
382 {
383 	struct clk *clk;
384 	struct dentry *d;
385 
386 	rootdir = debugfs_create_dir("clk", NULL);
387 
388 	if (!rootdir)
389 		return -ENOMEM;
390 
391 	d = debugfs_create_file("clk_summary", S_IRUGO, rootdir, &all_lists,
392 				&clk_summary_fops);
393 	if (!d)
394 		return -ENOMEM;
395 
396 	d = debugfs_create_file("clk_dump", S_IRUGO, rootdir, &all_lists,
397 				&clk_dump_fops);
398 	if (!d)
399 		return -ENOMEM;
400 
401 	d = debugfs_create_file("clk_orphan_summary", S_IRUGO, rootdir,
402 				&orphan_list, &clk_summary_fops);
403 	if (!d)
404 		return -ENOMEM;
405 
406 	d = debugfs_create_file("clk_orphan_dump", S_IRUGO, rootdir,
407 				&orphan_list, &clk_dump_fops);
408 	if (!d)
409 		return -ENOMEM;
410 
411 	mutex_lock(&clk_debug_lock);
412 	hlist_for_each_entry(clk, &clk_debug_list, debug_node)
413 		clk_debug_create_one(clk, rootdir);
414 
415 	inited = 1;
416 	mutex_unlock(&clk_debug_lock);
417 
418 	return 0;
419 }
420 late_initcall(clk_debug_init);
421 #else
422 static inline int clk_debug_register(struct clk *clk) { return 0; }
423 static inline void clk_debug_reparent(struct clk *clk, struct clk *new_parent)
424 {
425 }
426 static inline void clk_debug_unregister(struct clk *clk)
427 {
428 }
429 #endif
430 
431 /* caller must hold prepare_lock */
432 static void clk_unprepare_unused_subtree(struct clk *clk)
433 {
434 	struct clk *child;
435 
436 	if (!clk)
437 		return;
438 
439 	hlist_for_each_entry(child, &clk->children, child_node)
440 		clk_unprepare_unused_subtree(child);
441 
442 	if (clk->prepare_count)
443 		return;
444 
445 	if (clk->flags & CLK_IGNORE_UNUSED)
446 		return;
447 
448 	if (__clk_is_prepared(clk)) {
449 		if (clk->ops->unprepare_unused)
450 			clk->ops->unprepare_unused(clk->hw);
451 		else if (clk->ops->unprepare)
452 			clk->ops->unprepare(clk->hw);
453 	}
454 }
455 
456 /* caller must hold prepare_lock */
457 static void clk_disable_unused_subtree(struct clk *clk)
458 {
459 	struct clk *child;
460 	unsigned long flags;
461 
462 	if (!clk)
463 		goto out;
464 
465 	hlist_for_each_entry(child, &clk->children, child_node)
466 		clk_disable_unused_subtree(child);
467 
468 	flags = clk_enable_lock();
469 
470 	if (clk->enable_count)
471 		goto unlock_out;
472 
473 	if (clk->flags & CLK_IGNORE_UNUSED)
474 		goto unlock_out;
475 
476 	/*
477 	 * some gate clocks have special needs during the disable-unused
478 	 * sequence.  call .disable_unused if available, otherwise fall
479 	 * back to .disable
480 	 */
481 	if (__clk_is_enabled(clk)) {
482 		if (clk->ops->disable_unused)
483 			clk->ops->disable_unused(clk->hw);
484 		else if (clk->ops->disable)
485 			clk->ops->disable(clk->hw);
486 	}
487 
488 unlock_out:
489 	clk_enable_unlock(flags);
490 
491 out:
492 	return;
493 }
494 
495 static bool clk_ignore_unused;
496 static int __init clk_ignore_unused_setup(char *__unused)
497 {
498 	clk_ignore_unused = true;
499 	return 1;
500 }
501 __setup("clk_ignore_unused", clk_ignore_unused_setup);
502 
503 static int clk_disable_unused(void)
504 {
505 	struct clk *clk;
506 
507 	if (clk_ignore_unused) {
508 		pr_warn("clk: Not disabling unused clocks\n");
509 		return 0;
510 	}
511 
512 	clk_prepare_lock();
513 
514 	hlist_for_each_entry(clk, &clk_root_list, child_node)
515 		clk_disable_unused_subtree(clk);
516 
517 	hlist_for_each_entry(clk, &clk_orphan_list, child_node)
518 		clk_disable_unused_subtree(clk);
519 
520 	hlist_for_each_entry(clk, &clk_root_list, child_node)
521 		clk_unprepare_unused_subtree(clk);
522 
523 	hlist_for_each_entry(clk, &clk_orphan_list, child_node)
524 		clk_unprepare_unused_subtree(clk);
525 
526 	clk_prepare_unlock();
527 
528 	return 0;
529 }
530 late_initcall_sync(clk_disable_unused);
531 
532 /***    helper functions   ***/
533 
534 const char *__clk_get_name(struct clk *clk)
535 {
536 	return !clk ? NULL : clk->name;
537 }
538 EXPORT_SYMBOL_GPL(__clk_get_name);
539 
540 struct clk_hw *__clk_get_hw(struct clk *clk)
541 {
542 	return !clk ? NULL : clk->hw;
543 }
544 EXPORT_SYMBOL_GPL(__clk_get_hw);
545 
546 u8 __clk_get_num_parents(struct clk *clk)
547 {
548 	return !clk ? 0 : clk->num_parents;
549 }
550 EXPORT_SYMBOL_GPL(__clk_get_num_parents);
551 
552 struct clk *__clk_get_parent(struct clk *clk)
553 {
554 	return !clk ? NULL : clk->parent;
555 }
556 EXPORT_SYMBOL_GPL(__clk_get_parent);
557 
558 struct clk *clk_get_parent_by_index(struct clk *clk, u8 index)
559 {
560 	if (!clk || index >= clk->num_parents)
561 		return NULL;
562 	else if (!clk->parents)
563 		return __clk_lookup(clk->parent_names[index]);
564 	else if (!clk->parents[index])
565 		return clk->parents[index] =
566 			__clk_lookup(clk->parent_names[index]);
567 	else
568 		return clk->parents[index];
569 }
570 EXPORT_SYMBOL_GPL(clk_get_parent_by_index);
571 
572 unsigned int __clk_get_enable_count(struct clk *clk)
573 {
574 	return !clk ? 0 : clk->enable_count;
575 }
576 
577 unsigned int __clk_get_prepare_count(struct clk *clk)
578 {
579 	return !clk ? 0 : clk->prepare_count;
580 }
581 
582 unsigned long __clk_get_rate(struct clk *clk)
583 {
584 	unsigned long ret;
585 
586 	if (!clk) {
587 		ret = 0;
588 		goto out;
589 	}
590 
591 	ret = clk->rate;
592 
593 	if (clk->flags & CLK_IS_ROOT)
594 		goto out;
595 
596 	if (!clk->parent)
597 		ret = 0;
598 
599 out:
600 	return ret;
601 }
602 EXPORT_SYMBOL_GPL(__clk_get_rate);
603 
604 unsigned long __clk_get_accuracy(struct clk *clk)
605 {
606 	if (!clk)
607 		return 0;
608 
609 	return clk->accuracy;
610 }
611 
612 unsigned long __clk_get_flags(struct clk *clk)
613 {
614 	return !clk ? 0 : clk->flags;
615 }
616 EXPORT_SYMBOL_GPL(__clk_get_flags);
617 
618 bool __clk_is_prepared(struct clk *clk)
619 {
620 	int ret;
621 
622 	if (!clk)
623 		return false;
624 
625 	/*
626 	 * .is_prepared is optional for clocks that can prepare
627 	 * fall back to software usage counter if it is missing
628 	 */
629 	if (!clk->ops->is_prepared) {
630 		ret = clk->prepare_count ? 1 : 0;
631 		goto out;
632 	}
633 
634 	ret = clk->ops->is_prepared(clk->hw);
635 out:
636 	return !!ret;
637 }
638 
639 bool __clk_is_enabled(struct clk *clk)
640 {
641 	int ret;
642 
643 	if (!clk)
644 		return false;
645 
646 	/*
647 	 * .is_enabled is only mandatory for clocks that gate
648 	 * fall back to software usage counter if .is_enabled is missing
649 	 */
650 	if (!clk->ops->is_enabled) {
651 		ret = clk->enable_count ? 1 : 0;
652 		goto out;
653 	}
654 
655 	ret = clk->ops->is_enabled(clk->hw);
656 out:
657 	return !!ret;
658 }
659 EXPORT_SYMBOL_GPL(__clk_is_enabled);
660 
661 static struct clk *__clk_lookup_subtree(const char *name, struct clk *clk)
662 {
663 	struct clk *child;
664 	struct clk *ret;
665 
666 	if (!strcmp(clk->name, name))
667 		return clk;
668 
669 	hlist_for_each_entry(child, &clk->children, child_node) {
670 		ret = __clk_lookup_subtree(name, child);
671 		if (ret)
672 			return ret;
673 	}
674 
675 	return NULL;
676 }
677 
678 struct clk *__clk_lookup(const char *name)
679 {
680 	struct clk *root_clk;
681 	struct clk *ret;
682 
683 	if (!name)
684 		return NULL;
685 
686 	/* search the 'proper' clk tree first */
687 	hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
688 		ret = __clk_lookup_subtree(name, root_clk);
689 		if (ret)
690 			return ret;
691 	}
692 
693 	/* if not found, then search the orphan tree */
694 	hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
695 		ret = __clk_lookup_subtree(name, root_clk);
696 		if (ret)
697 			return ret;
698 	}
699 
700 	return NULL;
701 }
702 
703 /*
704  * Helper for finding best parent to provide a given frequency. This can be used
705  * directly as a determine_rate callback (e.g. for a mux), or from a more
706  * complex clock that may combine a mux with other operations.
707  */
708 long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
709 			      unsigned long *best_parent_rate,
710 			      struct clk **best_parent_p)
711 {
712 	struct clk *clk = hw->clk, *parent, *best_parent = NULL;
713 	int i, num_parents;
714 	unsigned long parent_rate, best = 0;
715 
716 	/* if NO_REPARENT flag set, pass through to current parent */
717 	if (clk->flags & CLK_SET_RATE_NO_REPARENT) {
718 		parent = clk->parent;
719 		if (clk->flags & CLK_SET_RATE_PARENT)
720 			best = __clk_round_rate(parent, rate);
721 		else if (parent)
722 			best = __clk_get_rate(parent);
723 		else
724 			best = __clk_get_rate(clk);
725 		goto out;
726 	}
727 
728 	/* find the parent that can provide the fastest rate <= rate */
729 	num_parents = clk->num_parents;
730 	for (i = 0; i < num_parents; i++) {
731 		parent = clk_get_parent_by_index(clk, i);
732 		if (!parent)
733 			continue;
734 		if (clk->flags & CLK_SET_RATE_PARENT)
735 			parent_rate = __clk_round_rate(parent, rate);
736 		else
737 			parent_rate = __clk_get_rate(parent);
738 		if (parent_rate <= rate && parent_rate > best) {
739 			best_parent = parent;
740 			best = parent_rate;
741 		}
742 	}
743 
744 out:
745 	if (best_parent)
746 		*best_parent_p = best_parent;
747 	*best_parent_rate = best;
748 
749 	return best;
750 }
751 EXPORT_SYMBOL_GPL(__clk_mux_determine_rate);
752 
753 /***        clk api        ***/
754 
755 void __clk_unprepare(struct clk *clk)
756 {
757 	if (!clk)
758 		return;
759 
760 	if (WARN_ON(clk->prepare_count == 0))
761 		return;
762 
763 	if (--clk->prepare_count > 0)
764 		return;
765 
766 	WARN_ON(clk->enable_count > 0);
767 
768 	if (clk->ops->unprepare)
769 		clk->ops->unprepare(clk->hw);
770 
771 	__clk_unprepare(clk->parent);
772 }
773 
774 /**
775  * clk_unprepare - undo preparation of a clock source
776  * @clk: the clk being unprepared
777  *
778  * clk_unprepare may sleep, which differentiates it from clk_disable.  In a
779  * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
780  * if the operation may sleep.  One example is a clk which is accessed over
781  * I2c.  In the complex case a clk gate operation may require a fast and a slow
782  * part.  It is this reason that clk_unprepare and clk_disable are not mutually
783  * exclusive.  In fact clk_disable must be called before clk_unprepare.
784  */
785 void clk_unprepare(struct clk *clk)
786 {
787 	if (IS_ERR_OR_NULL(clk))
788 		return;
789 
790 	clk_prepare_lock();
791 	__clk_unprepare(clk);
792 	clk_prepare_unlock();
793 }
794 EXPORT_SYMBOL_GPL(clk_unprepare);
795 
796 int __clk_prepare(struct clk *clk)
797 {
798 	int ret = 0;
799 
800 	if (!clk)
801 		return 0;
802 
803 	if (clk->prepare_count == 0) {
804 		ret = __clk_prepare(clk->parent);
805 		if (ret)
806 			return ret;
807 
808 		if (clk->ops->prepare) {
809 			ret = clk->ops->prepare(clk->hw);
810 			if (ret) {
811 				__clk_unprepare(clk->parent);
812 				return ret;
813 			}
814 		}
815 	}
816 
817 	clk->prepare_count++;
818 
819 	return 0;
820 }
821 
822 /**
823  * clk_prepare - prepare a clock source
824  * @clk: the clk being prepared
825  *
826  * clk_prepare may sleep, which differentiates it from clk_enable.  In a simple
827  * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
828  * operation may sleep.  One example is a clk which is accessed over I2c.  In
829  * the complex case a clk ungate operation may require a fast and a slow part.
830  * It is this reason that clk_prepare and clk_enable are not mutually
831  * exclusive.  In fact clk_prepare must be called before clk_enable.
832  * Returns 0 on success, -EERROR otherwise.
833  */
834 int clk_prepare(struct clk *clk)
835 {
836 	int ret;
837 
838 	clk_prepare_lock();
839 	ret = __clk_prepare(clk);
840 	clk_prepare_unlock();
841 
842 	return ret;
843 }
844 EXPORT_SYMBOL_GPL(clk_prepare);
845 
846 static void __clk_disable(struct clk *clk)
847 {
848 	if (!clk)
849 		return;
850 
851 	if (WARN_ON(clk->enable_count == 0))
852 		return;
853 
854 	if (--clk->enable_count > 0)
855 		return;
856 
857 	if (clk->ops->disable)
858 		clk->ops->disable(clk->hw);
859 
860 	__clk_disable(clk->parent);
861 }
862 
863 /**
864  * clk_disable - gate a clock
865  * @clk: the clk being gated
866  *
867  * clk_disable must not sleep, which differentiates it from clk_unprepare.  In
868  * a simple case, clk_disable can be used instead of clk_unprepare to gate a
869  * clk if the operation is fast and will never sleep.  One example is a
870  * SoC-internal clk which is controlled via simple register writes.  In the
871  * complex case a clk gate operation may require a fast and a slow part.  It is
872  * this reason that clk_unprepare and clk_disable are not mutually exclusive.
873  * In fact clk_disable must be called before clk_unprepare.
874  */
875 void clk_disable(struct clk *clk)
876 {
877 	unsigned long flags;
878 
879 	if (IS_ERR_OR_NULL(clk))
880 		return;
881 
882 	flags = clk_enable_lock();
883 	__clk_disable(clk);
884 	clk_enable_unlock(flags);
885 }
886 EXPORT_SYMBOL_GPL(clk_disable);
887 
888 static int __clk_enable(struct clk *clk)
889 {
890 	int ret = 0;
891 
892 	if (!clk)
893 		return 0;
894 
895 	if (WARN_ON(clk->prepare_count == 0))
896 		return -ESHUTDOWN;
897 
898 	if (clk->enable_count == 0) {
899 		ret = __clk_enable(clk->parent);
900 
901 		if (ret)
902 			return ret;
903 
904 		if (clk->ops->enable) {
905 			ret = clk->ops->enable(clk->hw);
906 			if (ret) {
907 				__clk_disable(clk->parent);
908 				return ret;
909 			}
910 		}
911 	}
912 
913 	clk->enable_count++;
914 	return 0;
915 }
916 
917 /**
918  * clk_enable - ungate a clock
919  * @clk: the clk being ungated
920  *
921  * clk_enable must not sleep, which differentiates it from clk_prepare.  In a
922  * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
923  * if the operation will never sleep.  One example is a SoC-internal clk which
924  * is controlled via simple register writes.  In the complex case a clk ungate
925  * operation may require a fast and a slow part.  It is this reason that
926  * clk_enable and clk_prepare are not mutually exclusive.  In fact clk_prepare
927  * must be called before clk_enable.  Returns 0 on success, -EERROR
928  * otherwise.
929  */
930 int clk_enable(struct clk *clk)
931 {
932 	unsigned long flags;
933 	int ret;
934 
935 	flags = clk_enable_lock();
936 	ret = __clk_enable(clk);
937 	clk_enable_unlock(flags);
938 
939 	return ret;
940 }
941 EXPORT_SYMBOL_GPL(clk_enable);
942 
943 /**
944  * __clk_round_rate - round the given rate for a clk
945  * @clk: round the rate of this clock
946  * @rate: the rate which is to be rounded
947  *
948  * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate
949  */
950 unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
951 {
952 	unsigned long parent_rate = 0;
953 	struct clk *parent;
954 
955 	if (!clk)
956 		return 0;
957 
958 	parent = clk->parent;
959 	if (parent)
960 		parent_rate = parent->rate;
961 
962 	if (clk->ops->determine_rate)
963 		return clk->ops->determine_rate(clk->hw, rate, &parent_rate,
964 						&parent);
965 	else if (clk->ops->round_rate)
966 		return clk->ops->round_rate(clk->hw, rate, &parent_rate);
967 	else if (clk->flags & CLK_SET_RATE_PARENT)
968 		return __clk_round_rate(clk->parent, rate);
969 	else
970 		return clk->rate;
971 }
972 EXPORT_SYMBOL_GPL(__clk_round_rate);
973 
974 /**
975  * clk_round_rate - round the given rate for a clk
976  * @clk: the clk for which we are rounding a rate
977  * @rate: the rate which is to be rounded
978  *
979  * Takes in a rate as input and rounds it to a rate that the clk can actually
980  * use which is then returned.  If clk doesn't support round_rate operation
981  * then the parent rate is returned.
982  */
983 long clk_round_rate(struct clk *clk, unsigned long rate)
984 {
985 	unsigned long ret;
986 
987 	clk_prepare_lock();
988 	ret = __clk_round_rate(clk, rate);
989 	clk_prepare_unlock();
990 
991 	return ret;
992 }
993 EXPORT_SYMBOL_GPL(clk_round_rate);
994 
995 /**
996  * __clk_notify - call clk notifier chain
997  * @clk: struct clk * that is changing rate
998  * @msg: clk notifier type (see include/linux/clk.h)
999  * @old_rate: old clk rate
1000  * @new_rate: new clk rate
1001  *
1002  * Triggers a notifier call chain on the clk rate-change notification
1003  * for 'clk'.  Passes a pointer to the struct clk and the previous
1004  * and current rates to the notifier callback.  Intended to be called by
1005  * internal clock code only.  Returns NOTIFY_DONE from the last driver
1006  * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
1007  * a driver returns that.
1008  */
1009 static int __clk_notify(struct clk *clk, unsigned long msg,
1010 		unsigned long old_rate, unsigned long new_rate)
1011 {
1012 	struct clk_notifier *cn;
1013 	struct clk_notifier_data cnd;
1014 	int ret = NOTIFY_DONE;
1015 
1016 	cnd.clk = clk;
1017 	cnd.old_rate = old_rate;
1018 	cnd.new_rate = new_rate;
1019 
1020 	list_for_each_entry(cn, &clk_notifier_list, node) {
1021 		if (cn->clk == clk) {
1022 			ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
1023 					&cnd);
1024 			break;
1025 		}
1026 	}
1027 
1028 	return ret;
1029 }
1030 
1031 /**
1032  * __clk_recalc_accuracies
1033  * @clk: first clk in the subtree
1034  *
1035  * Walks the subtree of clks starting with clk and recalculates accuracies as
1036  * it goes.  Note that if a clk does not implement the .recalc_accuracy
1037  * callback then it is assumed that the clock will take on the accuracy of it's
1038  * parent.
1039  *
1040  * Caller must hold prepare_lock.
1041  */
1042 static void __clk_recalc_accuracies(struct clk *clk)
1043 {
1044 	unsigned long parent_accuracy = 0;
1045 	struct clk *child;
1046 
1047 	if (clk->parent)
1048 		parent_accuracy = clk->parent->accuracy;
1049 
1050 	if (clk->ops->recalc_accuracy)
1051 		clk->accuracy = clk->ops->recalc_accuracy(clk->hw,
1052 							  parent_accuracy);
1053 	else
1054 		clk->accuracy = parent_accuracy;
1055 
1056 	hlist_for_each_entry(child, &clk->children, child_node)
1057 		__clk_recalc_accuracies(child);
1058 }
1059 
1060 /**
1061  * clk_get_accuracy - return the accuracy of clk
1062  * @clk: the clk whose accuracy is being returned
1063  *
1064  * Simply returns the cached accuracy of the clk, unless
1065  * CLK_GET_ACCURACY_NOCACHE flag is set, which means a recalc_rate will be
1066  * issued.
1067  * If clk is NULL then returns 0.
1068  */
1069 long clk_get_accuracy(struct clk *clk)
1070 {
1071 	unsigned long accuracy;
1072 
1073 	clk_prepare_lock();
1074 	if (clk && (clk->flags & CLK_GET_ACCURACY_NOCACHE))
1075 		__clk_recalc_accuracies(clk);
1076 
1077 	accuracy = __clk_get_accuracy(clk);
1078 	clk_prepare_unlock();
1079 
1080 	return accuracy;
1081 }
1082 EXPORT_SYMBOL_GPL(clk_get_accuracy);
1083 
1084 static unsigned long clk_recalc(struct clk *clk, unsigned long parent_rate)
1085 {
1086 	if (clk->ops->recalc_rate)
1087 		return clk->ops->recalc_rate(clk->hw, parent_rate);
1088 	return parent_rate;
1089 }
1090 
1091 /**
1092  * __clk_recalc_rates
1093  * @clk: first clk in the subtree
1094  * @msg: notification type (see include/linux/clk.h)
1095  *
1096  * Walks the subtree of clks starting with clk and recalculates rates as it
1097  * goes.  Note that if a clk does not implement the .recalc_rate callback then
1098  * it is assumed that the clock will take on the rate of its parent.
1099  *
1100  * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
1101  * if necessary.
1102  *
1103  * Caller must hold prepare_lock.
1104  */
1105 static void __clk_recalc_rates(struct clk *clk, unsigned long msg)
1106 {
1107 	unsigned long old_rate;
1108 	unsigned long parent_rate = 0;
1109 	struct clk *child;
1110 
1111 	old_rate = clk->rate;
1112 
1113 	if (clk->parent)
1114 		parent_rate = clk->parent->rate;
1115 
1116 	clk->rate = clk_recalc(clk, parent_rate);
1117 
1118 	/*
1119 	 * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
1120 	 * & ABORT_RATE_CHANGE notifiers
1121 	 */
1122 	if (clk->notifier_count && msg)
1123 		__clk_notify(clk, msg, old_rate, clk->rate);
1124 
1125 	hlist_for_each_entry(child, &clk->children, child_node)
1126 		__clk_recalc_rates(child, msg);
1127 }
1128 
1129 /**
1130  * clk_get_rate - return the rate of clk
1131  * @clk: the clk whose rate is being returned
1132  *
1133  * Simply returns the cached rate of the clk, unless CLK_GET_RATE_NOCACHE flag
1134  * is set, which means a recalc_rate will be issued.
1135  * If clk is NULL then returns 0.
1136  */
1137 unsigned long clk_get_rate(struct clk *clk)
1138 {
1139 	unsigned long rate;
1140 
1141 	clk_prepare_lock();
1142 
1143 	if (clk && (clk->flags & CLK_GET_RATE_NOCACHE))
1144 		__clk_recalc_rates(clk, 0);
1145 
1146 	rate = __clk_get_rate(clk);
1147 	clk_prepare_unlock();
1148 
1149 	return rate;
1150 }
1151 EXPORT_SYMBOL_GPL(clk_get_rate);
1152 
1153 static int clk_fetch_parent_index(struct clk *clk, struct clk *parent)
1154 {
1155 	int i;
1156 
1157 	if (!clk->parents) {
1158 		clk->parents = kcalloc(clk->num_parents,
1159 					sizeof(struct clk *), GFP_KERNEL);
1160 		if (!clk->parents)
1161 			return -ENOMEM;
1162 	}
1163 
1164 	/*
1165 	 * find index of new parent clock using cached parent ptrs,
1166 	 * or if not yet cached, use string name comparison and cache
1167 	 * them now to avoid future calls to __clk_lookup.
1168 	 */
1169 	for (i = 0; i < clk->num_parents; i++) {
1170 		if (clk->parents[i] == parent)
1171 			return i;
1172 
1173 		if (clk->parents[i])
1174 			continue;
1175 
1176 		if (!strcmp(clk->parent_names[i], parent->name)) {
1177 			clk->parents[i] = __clk_lookup(parent->name);
1178 			return i;
1179 		}
1180 	}
1181 
1182 	return -EINVAL;
1183 }
1184 
1185 static void clk_reparent(struct clk *clk, struct clk *new_parent)
1186 {
1187 	hlist_del(&clk->child_node);
1188 
1189 	if (new_parent) {
1190 		/* avoid duplicate POST_RATE_CHANGE notifications */
1191 		if (new_parent->new_child == clk)
1192 			new_parent->new_child = NULL;
1193 
1194 		hlist_add_head(&clk->child_node, &new_parent->children);
1195 	} else {
1196 		hlist_add_head(&clk->child_node, &clk_orphan_list);
1197 	}
1198 
1199 	clk->parent = new_parent;
1200 }
1201 
1202 static struct clk *__clk_set_parent_before(struct clk *clk, struct clk *parent)
1203 {
1204 	unsigned long flags;
1205 	struct clk *old_parent = clk->parent;
1206 
1207 	/*
1208 	 * Migrate prepare state between parents and prevent race with
1209 	 * clk_enable().
1210 	 *
1211 	 * If the clock is not prepared, then a race with
1212 	 * clk_enable/disable() is impossible since we already have the
1213 	 * prepare lock (future calls to clk_enable() need to be preceded by
1214 	 * a clk_prepare()).
1215 	 *
1216 	 * If the clock is prepared, migrate the prepared state to the new
1217 	 * parent and also protect against a race with clk_enable() by
1218 	 * forcing the clock and the new parent on.  This ensures that all
1219 	 * future calls to clk_enable() are practically NOPs with respect to
1220 	 * hardware and software states.
1221 	 *
1222 	 * See also: Comment for clk_set_parent() below.
1223 	 */
1224 	if (clk->prepare_count) {
1225 		__clk_prepare(parent);
1226 		clk_enable(parent);
1227 		clk_enable(clk);
1228 	}
1229 
1230 	/* update the clk tree topology */
1231 	flags = clk_enable_lock();
1232 	clk_reparent(clk, parent);
1233 	clk_enable_unlock(flags);
1234 
1235 	return old_parent;
1236 }
1237 
1238 static void __clk_set_parent_after(struct clk *clk, struct clk *parent,
1239 		struct clk *old_parent)
1240 {
1241 	/*
1242 	 * Finish the migration of prepare state and undo the changes done
1243 	 * for preventing a race with clk_enable().
1244 	 */
1245 	if (clk->prepare_count) {
1246 		clk_disable(clk);
1247 		clk_disable(old_parent);
1248 		__clk_unprepare(old_parent);
1249 	}
1250 }
1251 
1252 static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index)
1253 {
1254 	unsigned long flags;
1255 	int ret = 0;
1256 	struct clk *old_parent;
1257 
1258 	old_parent = __clk_set_parent_before(clk, parent);
1259 
1260 	/* change clock input source */
1261 	if (parent && clk->ops->set_parent)
1262 		ret = clk->ops->set_parent(clk->hw, p_index);
1263 
1264 	if (ret) {
1265 		flags = clk_enable_lock();
1266 		clk_reparent(clk, old_parent);
1267 		clk_enable_unlock(flags);
1268 
1269 		if (clk->prepare_count) {
1270 			clk_disable(clk);
1271 			clk_disable(parent);
1272 			__clk_unprepare(parent);
1273 		}
1274 		return ret;
1275 	}
1276 
1277 	__clk_set_parent_after(clk, parent, old_parent);
1278 
1279 	return 0;
1280 }
1281 
1282 /**
1283  * __clk_speculate_rates
1284  * @clk: first clk in the subtree
1285  * @parent_rate: the "future" rate of clk's parent
1286  *
1287  * Walks the subtree of clks starting with clk, speculating rates as it
1288  * goes and firing off PRE_RATE_CHANGE notifications as necessary.
1289  *
1290  * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
1291  * pre-rate change notifications and returns early if no clks in the
1292  * subtree have subscribed to the notifications.  Note that if a clk does not
1293  * implement the .recalc_rate callback then it is assumed that the clock will
1294  * take on the rate of its parent.
1295  *
1296  * Caller must hold prepare_lock.
1297  */
1298 static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
1299 {
1300 	struct clk *child;
1301 	unsigned long new_rate;
1302 	int ret = NOTIFY_DONE;
1303 
1304 	new_rate = clk_recalc(clk, parent_rate);
1305 
1306 	/* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
1307 	if (clk->notifier_count)
1308 		ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
1309 
1310 	if (ret & NOTIFY_STOP_MASK) {
1311 		pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n",
1312 				__func__, clk->name, ret);
1313 		goto out;
1314 	}
1315 
1316 	hlist_for_each_entry(child, &clk->children, child_node) {
1317 		ret = __clk_speculate_rates(child, new_rate);
1318 		if (ret & NOTIFY_STOP_MASK)
1319 			break;
1320 	}
1321 
1322 out:
1323 	return ret;
1324 }
1325 
1326 static void clk_calc_subtree(struct clk *clk, unsigned long new_rate,
1327 			     struct clk *new_parent, u8 p_index)
1328 {
1329 	struct clk *child;
1330 
1331 	clk->new_rate = new_rate;
1332 	clk->new_parent = new_parent;
1333 	clk->new_parent_index = p_index;
1334 	/* include clk in new parent's PRE_RATE_CHANGE notifications */
1335 	clk->new_child = NULL;
1336 	if (new_parent && new_parent != clk->parent)
1337 		new_parent->new_child = clk;
1338 
1339 	hlist_for_each_entry(child, &clk->children, child_node) {
1340 		child->new_rate = clk_recalc(child, new_rate);
1341 		clk_calc_subtree(child, child->new_rate, NULL, 0);
1342 	}
1343 }
1344 
1345 /*
1346  * calculate the new rates returning the topmost clock that has to be
1347  * changed.
1348  */
1349 static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
1350 {
1351 	struct clk *top = clk;
1352 	struct clk *old_parent, *parent;
1353 	unsigned long best_parent_rate = 0;
1354 	unsigned long new_rate;
1355 	int p_index = 0;
1356 
1357 	/* sanity */
1358 	if (IS_ERR_OR_NULL(clk))
1359 		return NULL;
1360 
1361 	/* save parent rate, if it exists */
1362 	parent = old_parent = clk->parent;
1363 	if (parent)
1364 		best_parent_rate = parent->rate;
1365 
1366 	/* find the closest rate and parent clk/rate */
1367 	if (clk->ops->determine_rate) {
1368 		new_rate = clk->ops->determine_rate(clk->hw, rate,
1369 						    &best_parent_rate,
1370 						    &parent);
1371 	} else if (clk->ops->round_rate) {
1372 		new_rate = clk->ops->round_rate(clk->hw, rate,
1373 						&best_parent_rate);
1374 	} else if (!parent || !(clk->flags & CLK_SET_RATE_PARENT)) {
1375 		/* pass-through clock without adjustable parent */
1376 		clk->new_rate = clk->rate;
1377 		return NULL;
1378 	} else {
1379 		/* pass-through clock with adjustable parent */
1380 		top = clk_calc_new_rates(parent, rate);
1381 		new_rate = parent->new_rate;
1382 		goto out;
1383 	}
1384 
1385 	/* some clocks must be gated to change parent */
1386 	if (parent != old_parent &&
1387 	    (clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) {
1388 		pr_debug("%s: %s not gated but wants to reparent\n",
1389 			 __func__, clk->name);
1390 		return NULL;
1391 	}
1392 
1393 	/* try finding the new parent index */
1394 	if (parent) {
1395 		p_index = clk_fetch_parent_index(clk, parent);
1396 		if (p_index < 0) {
1397 			pr_debug("%s: clk %s can not be parent of clk %s\n",
1398 				 __func__, parent->name, clk->name);
1399 			return NULL;
1400 		}
1401 	}
1402 
1403 	if ((clk->flags & CLK_SET_RATE_PARENT) && parent &&
1404 	    best_parent_rate != parent->rate)
1405 		top = clk_calc_new_rates(parent, best_parent_rate);
1406 
1407 out:
1408 	clk_calc_subtree(clk, new_rate, parent, p_index);
1409 
1410 	return top;
1411 }
1412 
1413 /*
1414  * Notify about rate changes in a subtree. Always walk down the whole tree
1415  * so that in case of an error we can walk down the whole tree again and
1416  * abort the change.
1417  */
1418 static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
1419 {
1420 	struct clk *child, *tmp_clk, *fail_clk = NULL;
1421 	int ret = NOTIFY_DONE;
1422 
1423 	if (clk->rate == clk->new_rate)
1424 		return NULL;
1425 
1426 	if (clk->notifier_count) {
1427 		ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
1428 		if (ret & NOTIFY_STOP_MASK)
1429 			fail_clk = clk;
1430 	}
1431 
1432 	hlist_for_each_entry(child, &clk->children, child_node) {
1433 		/* Skip children who will be reparented to another clock */
1434 		if (child->new_parent && child->new_parent != clk)
1435 			continue;
1436 		tmp_clk = clk_propagate_rate_change(child, event);
1437 		if (tmp_clk)
1438 			fail_clk = tmp_clk;
1439 	}
1440 
1441 	/* handle the new child who might not be in clk->children yet */
1442 	if (clk->new_child) {
1443 		tmp_clk = clk_propagate_rate_change(clk->new_child, event);
1444 		if (tmp_clk)
1445 			fail_clk = tmp_clk;
1446 	}
1447 
1448 	return fail_clk;
1449 }
1450 
1451 /*
1452  * walk down a subtree and set the new rates notifying the rate
1453  * change on the way
1454  */
1455 static void clk_change_rate(struct clk *clk)
1456 {
1457 	struct clk *child;
1458 	struct hlist_node *tmp;
1459 	unsigned long old_rate;
1460 	unsigned long best_parent_rate = 0;
1461 	bool skip_set_rate = false;
1462 	struct clk *old_parent;
1463 
1464 	old_rate = clk->rate;
1465 
1466 	if (clk->new_parent)
1467 		best_parent_rate = clk->new_parent->rate;
1468 	else if (clk->parent)
1469 		best_parent_rate = clk->parent->rate;
1470 
1471 	if (clk->new_parent && clk->new_parent != clk->parent) {
1472 		old_parent = __clk_set_parent_before(clk, clk->new_parent);
1473 
1474 		if (clk->ops->set_rate_and_parent) {
1475 			skip_set_rate = true;
1476 			clk->ops->set_rate_and_parent(clk->hw, clk->new_rate,
1477 					best_parent_rate,
1478 					clk->new_parent_index);
1479 		} else if (clk->ops->set_parent) {
1480 			clk->ops->set_parent(clk->hw, clk->new_parent_index);
1481 		}
1482 
1483 		__clk_set_parent_after(clk, clk->new_parent, old_parent);
1484 	}
1485 
1486 	if (!skip_set_rate && clk->ops->set_rate)
1487 		clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate);
1488 
1489 	clk->rate = clk_recalc(clk, best_parent_rate);
1490 
1491 	if (clk->notifier_count && old_rate != clk->rate)
1492 		__clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
1493 
1494 	/*
1495 	 * Use safe iteration, as change_rate can actually swap parents
1496 	 * for certain clock types.
1497 	 */
1498 	hlist_for_each_entry_safe(child, tmp, &clk->children, child_node) {
1499 		/* Skip children who will be reparented to another clock */
1500 		if (child->new_parent && child->new_parent != clk)
1501 			continue;
1502 		clk_change_rate(child);
1503 	}
1504 
1505 	/* handle the new child who might not be in clk->children yet */
1506 	if (clk->new_child)
1507 		clk_change_rate(clk->new_child);
1508 }
1509 
1510 /**
1511  * clk_set_rate - specify a new rate for clk
1512  * @clk: the clk whose rate is being changed
1513  * @rate: the new rate for clk
1514  *
1515  * In the simplest case clk_set_rate will only adjust the rate of clk.
1516  *
1517  * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
1518  * propagate up to clk's parent; whether or not this happens depends on the
1519  * outcome of clk's .round_rate implementation.  If *parent_rate is unchanged
1520  * after calling .round_rate then upstream parent propagation is ignored.  If
1521  * *parent_rate comes back with a new rate for clk's parent then we propagate
1522  * up to clk's parent and set its rate.  Upward propagation will continue
1523  * until either a clk does not support the CLK_SET_RATE_PARENT flag or
1524  * .round_rate stops requesting changes to clk's parent_rate.
1525  *
1526  * Rate changes are accomplished via tree traversal that also recalculates the
1527  * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
1528  *
1529  * Returns 0 on success, -EERROR otherwise.
1530  */
1531 int clk_set_rate(struct clk *clk, unsigned long rate)
1532 {
1533 	struct clk *top, *fail_clk;
1534 	int ret = 0;
1535 
1536 	if (!clk)
1537 		return 0;
1538 
1539 	/* prevent racing with updates to the clock topology */
1540 	clk_prepare_lock();
1541 
1542 	/* bail early if nothing to do */
1543 	if (rate == clk_get_rate(clk))
1544 		goto out;
1545 
1546 	if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) {
1547 		ret = -EBUSY;
1548 		goto out;
1549 	}
1550 
1551 	/* calculate new rates and get the topmost changed clock */
1552 	top = clk_calc_new_rates(clk, rate);
1553 	if (!top) {
1554 		ret = -EINVAL;
1555 		goto out;
1556 	}
1557 
1558 	/* notify that we are about to change rates */
1559 	fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
1560 	if (fail_clk) {
1561 		pr_debug("%s: failed to set %s rate\n", __func__,
1562 				fail_clk->name);
1563 		clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
1564 		ret = -EBUSY;
1565 		goto out;
1566 	}
1567 
1568 	/* change the rates */
1569 	clk_change_rate(top);
1570 
1571 out:
1572 	clk_prepare_unlock();
1573 
1574 	return ret;
1575 }
1576 EXPORT_SYMBOL_GPL(clk_set_rate);
1577 
1578 /**
1579  * clk_get_parent - return the parent of a clk
1580  * @clk: the clk whose parent gets returned
1581  *
1582  * Simply returns clk->parent.  Returns NULL if clk is NULL.
1583  */
1584 struct clk *clk_get_parent(struct clk *clk)
1585 {
1586 	struct clk *parent;
1587 
1588 	clk_prepare_lock();
1589 	parent = __clk_get_parent(clk);
1590 	clk_prepare_unlock();
1591 
1592 	return parent;
1593 }
1594 EXPORT_SYMBOL_GPL(clk_get_parent);
1595 
1596 /*
1597  * .get_parent is mandatory for clocks with multiple possible parents.  It is
1598  * optional for single-parent clocks.  Always call .get_parent if it is
1599  * available and WARN if it is missing for multi-parent clocks.
1600  *
1601  * For single-parent clocks without .get_parent, first check to see if the
1602  * .parents array exists, and if so use it to avoid an expensive tree
1603  * traversal.  If .parents does not exist then walk the tree with __clk_lookup.
1604  */
1605 static struct clk *__clk_init_parent(struct clk *clk)
1606 {
1607 	struct clk *ret = NULL;
1608 	u8 index;
1609 
1610 	/* handle the trivial cases */
1611 
1612 	if (!clk->num_parents)
1613 		goto out;
1614 
1615 	if (clk->num_parents == 1) {
1616 		if (IS_ERR_OR_NULL(clk->parent))
1617 			ret = clk->parent = __clk_lookup(clk->parent_names[0]);
1618 		ret = clk->parent;
1619 		goto out;
1620 	}
1621 
1622 	if (!clk->ops->get_parent) {
1623 		WARN(!clk->ops->get_parent,
1624 			"%s: multi-parent clocks must implement .get_parent\n",
1625 			__func__);
1626 		goto out;
1627 	};
1628 
1629 	/*
1630 	 * Do our best to cache parent clocks in clk->parents.  This prevents
1631 	 * unnecessary and expensive calls to __clk_lookup.  We don't set
1632 	 * clk->parent here; that is done by the calling function
1633 	 */
1634 
1635 	index = clk->ops->get_parent(clk->hw);
1636 
1637 	if (!clk->parents)
1638 		clk->parents =
1639 			kcalloc(clk->num_parents, sizeof(struct clk *),
1640 					GFP_KERNEL);
1641 
1642 	ret = clk_get_parent_by_index(clk, index);
1643 
1644 out:
1645 	return ret;
1646 }
1647 
1648 void __clk_reparent(struct clk *clk, struct clk *new_parent)
1649 {
1650 	clk_reparent(clk, new_parent);
1651 	__clk_recalc_accuracies(clk);
1652 	__clk_recalc_rates(clk, POST_RATE_CHANGE);
1653 }
1654 
1655 /**
1656  * clk_set_parent - switch the parent of a mux clk
1657  * @clk: the mux clk whose input we are switching
1658  * @parent: the new input to clk
1659  *
1660  * Re-parent clk to use parent as its new input source.  If clk is in
1661  * prepared state, the clk will get enabled for the duration of this call. If
1662  * that's not acceptable for a specific clk (Eg: the consumer can't handle
1663  * that, the reparenting is glitchy in hardware, etc), use the
1664  * CLK_SET_PARENT_GATE flag to allow reparenting only when clk is unprepared.
1665  *
1666  * After successfully changing clk's parent clk_set_parent will update the
1667  * clk topology, sysfs topology and propagate rate recalculation via
1668  * __clk_recalc_rates.
1669  *
1670  * Returns 0 on success, -EERROR otherwise.
1671  */
1672 int clk_set_parent(struct clk *clk, struct clk *parent)
1673 {
1674 	int ret = 0;
1675 	int p_index = 0;
1676 	unsigned long p_rate = 0;
1677 
1678 	if (!clk)
1679 		return 0;
1680 
1681 	/* verify ops for for multi-parent clks */
1682 	if ((clk->num_parents > 1) && (!clk->ops->set_parent))
1683 		return -ENOSYS;
1684 
1685 	/* prevent racing with updates to the clock topology */
1686 	clk_prepare_lock();
1687 
1688 	if (clk->parent == parent)
1689 		goto out;
1690 
1691 	/* check that we are allowed to re-parent if the clock is in use */
1692 	if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) {
1693 		ret = -EBUSY;
1694 		goto out;
1695 	}
1696 
1697 	/* try finding the new parent index */
1698 	if (parent) {
1699 		p_index = clk_fetch_parent_index(clk, parent);
1700 		p_rate = parent->rate;
1701 		if (p_index < 0) {
1702 			pr_debug("%s: clk %s can not be parent of clk %s\n",
1703 					__func__, parent->name, clk->name);
1704 			ret = p_index;
1705 			goto out;
1706 		}
1707 	}
1708 
1709 	/* propagate PRE_RATE_CHANGE notifications */
1710 	ret = __clk_speculate_rates(clk, p_rate);
1711 
1712 	/* abort if a driver objects */
1713 	if (ret & NOTIFY_STOP_MASK)
1714 		goto out;
1715 
1716 	/* do the re-parent */
1717 	ret = __clk_set_parent(clk, parent, p_index);
1718 
1719 	/* propagate rate an accuracy recalculation accordingly */
1720 	if (ret) {
1721 		__clk_recalc_rates(clk, ABORT_RATE_CHANGE);
1722 	} else {
1723 		__clk_recalc_rates(clk, POST_RATE_CHANGE);
1724 		__clk_recalc_accuracies(clk);
1725 	}
1726 
1727 out:
1728 	clk_prepare_unlock();
1729 
1730 	return ret;
1731 }
1732 EXPORT_SYMBOL_GPL(clk_set_parent);
1733 
1734 /**
1735  * clk_set_phase - adjust the phase shift of a clock signal
1736  * @clk: clock signal source
1737  * @degrees: number of degrees the signal is shifted
1738  *
1739  * Shifts the phase of a clock signal by the specified
1740  * degrees. Returns 0 on success, -EERROR otherwise.
1741  *
1742  * This function makes no distinction about the input or reference
1743  * signal that we adjust the clock signal phase against. For example
1744  * phase locked-loop clock signal generators we may shift phase with
1745  * respect to feedback clock signal input, but for other cases the
1746  * clock phase may be shifted with respect to some other, unspecified
1747  * signal.
1748  *
1749  * Additionally the concept of phase shift does not propagate through
1750  * the clock tree hierarchy, which sets it apart from clock rates and
1751  * clock accuracy. A parent clock phase attribute does not have an
1752  * impact on the phase attribute of a child clock.
1753  */
1754 int clk_set_phase(struct clk *clk, int degrees)
1755 {
1756 	int ret = 0;
1757 
1758 	if (!clk)
1759 		goto out;
1760 
1761 	/* sanity check degrees */
1762 	degrees %= 360;
1763 	if (degrees < 0)
1764 		degrees += 360;
1765 
1766 	clk_prepare_lock();
1767 
1768 	if (!clk->ops->set_phase)
1769 		goto out_unlock;
1770 
1771 	ret = clk->ops->set_phase(clk->hw, degrees);
1772 
1773 	if (!ret)
1774 		clk->phase = degrees;
1775 
1776 out_unlock:
1777 	clk_prepare_unlock();
1778 
1779 out:
1780 	return ret;
1781 }
1782 
1783 /**
1784  * clk_get_phase - return the phase shift of a clock signal
1785  * @clk: clock signal source
1786  *
1787  * Returns the phase shift of a clock node in degrees, otherwise returns
1788  * -EERROR.
1789  */
1790 int clk_get_phase(struct clk *clk)
1791 {
1792 	int ret = 0;
1793 
1794 	if (!clk)
1795 		goto out;
1796 
1797 	clk_prepare_lock();
1798 	ret = clk->phase;
1799 	clk_prepare_unlock();
1800 
1801 out:
1802 	return ret;
1803 }
1804 
1805 /**
1806  * __clk_init - initialize the data structures in a struct clk
1807  * @dev:	device initializing this clk, placeholder for now
1808  * @clk:	clk being initialized
1809  *
1810  * Initializes the lists in struct clk, queries the hardware for the
1811  * parent and rate and sets them both.
1812  */
1813 int __clk_init(struct device *dev, struct clk *clk)
1814 {
1815 	int i, ret = 0;
1816 	struct clk *orphan;
1817 	struct hlist_node *tmp2;
1818 
1819 	if (!clk)
1820 		return -EINVAL;
1821 
1822 	clk_prepare_lock();
1823 
1824 	/* check to see if a clock with this name is already registered */
1825 	if (__clk_lookup(clk->name)) {
1826 		pr_debug("%s: clk %s already initialized\n",
1827 				__func__, clk->name);
1828 		ret = -EEXIST;
1829 		goto out;
1830 	}
1831 
1832 	/* check that clk_ops are sane.  See Documentation/clk.txt */
1833 	if (clk->ops->set_rate &&
1834 	    !((clk->ops->round_rate || clk->ops->determine_rate) &&
1835 	      clk->ops->recalc_rate)) {
1836 		pr_warning("%s: %s must implement .round_rate or .determine_rate in addition to .recalc_rate\n",
1837 				__func__, clk->name);
1838 		ret = -EINVAL;
1839 		goto out;
1840 	}
1841 
1842 	if (clk->ops->set_parent && !clk->ops->get_parent) {
1843 		pr_warning("%s: %s must implement .get_parent & .set_parent\n",
1844 				__func__, clk->name);
1845 		ret = -EINVAL;
1846 		goto out;
1847 	}
1848 
1849 	if (clk->ops->set_rate_and_parent &&
1850 			!(clk->ops->set_parent && clk->ops->set_rate)) {
1851 		pr_warn("%s: %s must implement .set_parent & .set_rate\n",
1852 				__func__, clk->name);
1853 		ret = -EINVAL;
1854 		goto out;
1855 	}
1856 
1857 	/* throw a WARN if any entries in parent_names are NULL */
1858 	for (i = 0; i < clk->num_parents; i++)
1859 		WARN(!clk->parent_names[i],
1860 				"%s: invalid NULL in %s's .parent_names\n",
1861 				__func__, clk->name);
1862 
1863 	/*
1864 	 * Allocate an array of struct clk *'s to avoid unnecessary string
1865 	 * look-ups of clk's possible parents.  This can fail for clocks passed
1866 	 * in to clk_init during early boot; thus any access to clk->parents[]
1867 	 * must always check for a NULL pointer and try to populate it if
1868 	 * necessary.
1869 	 *
1870 	 * If clk->parents is not NULL we skip this entire block.  This allows
1871 	 * for clock drivers to statically initialize clk->parents.
1872 	 */
1873 	if (clk->num_parents > 1 && !clk->parents) {
1874 		clk->parents = kcalloc(clk->num_parents, sizeof(struct clk *),
1875 					GFP_KERNEL);
1876 		/*
1877 		 * __clk_lookup returns NULL for parents that have not been
1878 		 * clk_init'd; thus any access to clk->parents[] must check
1879 		 * for a NULL pointer.  We can always perform lazy lookups for
1880 		 * missing parents later on.
1881 		 */
1882 		if (clk->parents)
1883 			for (i = 0; i < clk->num_parents; i++)
1884 				clk->parents[i] =
1885 					__clk_lookup(clk->parent_names[i]);
1886 	}
1887 
1888 	clk->parent = __clk_init_parent(clk);
1889 
1890 	/*
1891 	 * Populate clk->parent if parent has already been __clk_init'd.  If
1892 	 * parent has not yet been __clk_init'd then place clk in the orphan
1893 	 * list.  If clk has set the CLK_IS_ROOT flag then place it in the root
1894 	 * clk list.
1895 	 *
1896 	 * Every time a new clk is clk_init'd then we walk the list of orphan
1897 	 * clocks and re-parent any that are children of the clock currently
1898 	 * being clk_init'd.
1899 	 */
1900 	if (clk->parent)
1901 		hlist_add_head(&clk->child_node,
1902 				&clk->parent->children);
1903 	else if (clk->flags & CLK_IS_ROOT)
1904 		hlist_add_head(&clk->child_node, &clk_root_list);
1905 	else
1906 		hlist_add_head(&clk->child_node, &clk_orphan_list);
1907 
1908 	/*
1909 	 * Set clk's accuracy.  The preferred method is to use
1910 	 * .recalc_accuracy. For simple clocks and lazy developers the default
1911 	 * fallback is to use the parent's accuracy.  If a clock doesn't have a
1912 	 * parent (or is orphaned) then accuracy is set to zero (perfect
1913 	 * clock).
1914 	 */
1915 	if (clk->ops->recalc_accuracy)
1916 		clk->accuracy = clk->ops->recalc_accuracy(clk->hw,
1917 					__clk_get_accuracy(clk->parent));
1918 	else if (clk->parent)
1919 		clk->accuracy = clk->parent->accuracy;
1920 	else
1921 		clk->accuracy = 0;
1922 
1923 	/*
1924 	 * Set clk's phase.
1925 	 * Since a phase is by definition relative to its parent, just
1926 	 * query the current clock phase, or just assume it's in phase.
1927 	 */
1928 	if (clk->ops->get_phase)
1929 		clk->phase = clk->ops->get_phase(clk->hw);
1930 	else
1931 		clk->phase = 0;
1932 
1933 	/*
1934 	 * Set clk's rate.  The preferred method is to use .recalc_rate.  For
1935 	 * simple clocks and lazy developers the default fallback is to use the
1936 	 * parent's rate.  If a clock doesn't have a parent (or is orphaned)
1937 	 * then rate is set to zero.
1938 	 */
1939 	if (clk->ops->recalc_rate)
1940 		clk->rate = clk->ops->recalc_rate(clk->hw,
1941 				__clk_get_rate(clk->parent));
1942 	else if (clk->parent)
1943 		clk->rate = clk->parent->rate;
1944 	else
1945 		clk->rate = 0;
1946 
1947 	clk_debug_register(clk);
1948 	/*
1949 	 * walk the list of orphan clocks and reparent any that are children of
1950 	 * this clock
1951 	 */
1952 	hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
1953 		if (orphan->num_parents && orphan->ops->get_parent) {
1954 			i = orphan->ops->get_parent(orphan->hw);
1955 			if (!strcmp(clk->name, orphan->parent_names[i]))
1956 				__clk_reparent(orphan, clk);
1957 			continue;
1958 		}
1959 
1960 		for (i = 0; i < orphan->num_parents; i++)
1961 			if (!strcmp(clk->name, orphan->parent_names[i])) {
1962 				__clk_reparent(orphan, clk);
1963 				break;
1964 			}
1965 	 }
1966 
1967 	/*
1968 	 * optional platform-specific magic
1969 	 *
1970 	 * The .init callback is not used by any of the basic clock types, but
1971 	 * exists for weird hardware that must perform initialization magic.
1972 	 * Please consider other ways of solving initialization problems before
1973 	 * using this callback, as its use is discouraged.
1974 	 */
1975 	if (clk->ops->init)
1976 		clk->ops->init(clk->hw);
1977 
1978 	kref_init(&clk->ref);
1979 out:
1980 	clk_prepare_unlock();
1981 
1982 	return ret;
1983 }
1984 
1985 /**
1986  * __clk_register - register a clock and return a cookie.
1987  *
1988  * Same as clk_register, except that the .clk field inside hw shall point to a
1989  * preallocated (generally statically allocated) struct clk. None of the fields
1990  * of the struct clk need to be initialized.
1991  *
1992  * The data pointed to by .init and .clk field shall NOT be marked as init
1993  * data.
1994  *
1995  * __clk_register is only exposed via clk-private.h and is intended for use with
1996  * very large numbers of clocks that need to be statically initialized.  It is
1997  * a layering violation to include clk-private.h from any code which implements
1998  * a clock's .ops; as such any statically initialized clock data MUST be in a
1999  * separate C file from the logic that implements its operations.  Returns 0
2000  * on success, otherwise an error code.
2001  */
2002 struct clk *__clk_register(struct device *dev, struct clk_hw *hw)
2003 {
2004 	int ret;
2005 	struct clk *clk;
2006 
2007 	clk = hw->clk;
2008 	clk->name = hw->init->name;
2009 	clk->ops = hw->init->ops;
2010 	clk->hw = hw;
2011 	clk->flags = hw->init->flags;
2012 	clk->parent_names = hw->init->parent_names;
2013 	clk->num_parents = hw->init->num_parents;
2014 	if (dev && dev->driver)
2015 		clk->owner = dev->driver->owner;
2016 	else
2017 		clk->owner = NULL;
2018 
2019 	ret = __clk_init(dev, clk);
2020 	if (ret)
2021 		return ERR_PTR(ret);
2022 
2023 	return clk;
2024 }
2025 EXPORT_SYMBOL_GPL(__clk_register);
2026 
2027 /**
2028  * clk_register - allocate a new clock, register it and return an opaque cookie
2029  * @dev: device that is registering this clock
2030  * @hw: link to hardware-specific clock data
2031  *
2032  * clk_register is the primary interface for populating the clock tree with new
2033  * clock nodes.  It returns a pointer to the newly allocated struct clk which
2034  * cannot be dereferenced by driver code but may be used in conjuction with the
2035  * rest of the clock API.  In the event of an error clk_register will return an
2036  * error code; drivers must test for an error code after calling clk_register.
2037  */
2038 struct clk *clk_register(struct device *dev, struct clk_hw *hw)
2039 {
2040 	int i, ret;
2041 	struct clk *clk;
2042 
2043 	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
2044 	if (!clk) {
2045 		pr_err("%s: could not allocate clk\n", __func__);
2046 		ret = -ENOMEM;
2047 		goto fail_out;
2048 	}
2049 
2050 	clk->name = kstrdup(hw->init->name, GFP_KERNEL);
2051 	if (!clk->name) {
2052 		pr_err("%s: could not allocate clk->name\n", __func__);
2053 		ret = -ENOMEM;
2054 		goto fail_name;
2055 	}
2056 	clk->ops = hw->init->ops;
2057 	if (dev && dev->driver)
2058 		clk->owner = dev->driver->owner;
2059 	clk->hw = hw;
2060 	clk->flags = hw->init->flags;
2061 	clk->num_parents = hw->init->num_parents;
2062 	hw->clk = clk;
2063 
2064 	/* allocate local copy in case parent_names is __initdata */
2065 	clk->parent_names = kcalloc(clk->num_parents, sizeof(char *),
2066 					GFP_KERNEL);
2067 
2068 	if (!clk->parent_names) {
2069 		pr_err("%s: could not allocate clk->parent_names\n", __func__);
2070 		ret = -ENOMEM;
2071 		goto fail_parent_names;
2072 	}
2073 
2074 
2075 	/* copy each string name in case parent_names is __initdata */
2076 	for (i = 0; i < clk->num_parents; i++) {
2077 		clk->parent_names[i] = kstrdup(hw->init->parent_names[i],
2078 						GFP_KERNEL);
2079 		if (!clk->parent_names[i]) {
2080 			pr_err("%s: could not copy parent_names\n", __func__);
2081 			ret = -ENOMEM;
2082 			goto fail_parent_names_copy;
2083 		}
2084 	}
2085 
2086 	ret = __clk_init(dev, clk);
2087 	if (!ret)
2088 		return clk;
2089 
2090 fail_parent_names_copy:
2091 	while (--i >= 0)
2092 		kfree(clk->parent_names[i]);
2093 	kfree(clk->parent_names);
2094 fail_parent_names:
2095 	kfree(clk->name);
2096 fail_name:
2097 	kfree(clk);
2098 fail_out:
2099 	return ERR_PTR(ret);
2100 }
2101 EXPORT_SYMBOL_GPL(clk_register);
2102 
2103 /*
2104  * Free memory allocated for a clock.
2105  * Caller must hold prepare_lock.
2106  */
2107 static void __clk_release(struct kref *ref)
2108 {
2109 	struct clk *clk = container_of(ref, struct clk, ref);
2110 	int i = clk->num_parents;
2111 
2112 	kfree(clk->parents);
2113 	while (--i >= 0)
2114 		kfree(clk->parent_names[i]);
2115 
2116 	kfree(clk->parent_names);
2117 	kfree(clk->name);
2118 	kfree(clk);
2119 }
2120 
2121 /*
2122  * Empty clk_ops for unregistered clocks. These are used temporarily
2123  * after clk_unregister() was called on a clock and until last clock
2124  * consumer calls clk_put() and the struct clk object is freed.
2125  */
2126 static int clk_nodrv_prepare_enable(struct clk_hw *hw)
2127 {
2128 	return -ENXIO;
2129 }
2130 
2131 static void clk_nodrv_disable_unprepare(struct clk_hw *hw)
2132 {
2133 	WARN_ON_ONCE(1);
2134 }
2135 
2136 static int clk_nodrv_set_rate(struct clk_hw *hw, unsigned long rate,
2137 					unsigned long parent_rate)
2138 {
2139 	return -ENXIO;
2140 }
2141 
2142 static int clk_nodrv_set_parent(struct clk_hw *hw, u8 index)
2143 {
2144 	return -ENXIO;
2145 }
2146 
2147 static const struct clk_ops clk_nodrv_ops = {
2148 	.enable		= clk_nodrv_prepare_enable,
2149 	.disable	= clk_nodrv_disable_unprepare,
2150 	.prepare	= clk_nodrv_prepare_enable,
2151 	.unprepare	= clk_nodrv_disable_unprepare,
2152 	.set_rate	= clk_nodrv_set_rate,
2153 	.set_parent	= clk_nodrv_set_parent,
2154 };
2155 
2156 /**
2157  * clk_unregister - unregister a currently registered clock
2158  * @clk: clock to unregister
2159  */
2160 void clk_unregister(struct clk *clk)
2161 {
2162 	unsigned long flags;
2163 
2164 	if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
2165 		return;
2166 
2167 	clk_debug_unregister(clk);
2168 
2169 	clk_prepare_lock();
2170 
2171 	if (clk->ops == &clk_nodrv_ops) {
2172 		pr_err("%s: unregistered clock: %s\n", __func__, clk->name);
2173 		return;
2174 	}
2175 	/*
2176 	 * Assign empty clock ops for consumers that might still hold
2177 	 * a reference to this clock.
2178 	 */
2179 	flags = clk_enable_lock();
2180 	clk->ops = &clk_nodrv_ops;
2181 	clk_enable_unlock(flags);
2182 
2183 	if (!hlist_empty(&clk->children)) {
2184 		struct clk *child;
2185 		struct hlist_node *t;
2186 
2187 		/* Reparent all children to the orphan list. */
2188 		hlist_for_each_entry_safe(child, t, &clk->children, child_node)
2189 			clk_set_parent(child, NULL);
2190 	}
2191 
2192 	hlist_del_init(&clk->child_node);
2193 
2194 	if (clk->prepare_count)
2195 		pr_warn("%s: unregistering prepared clock: %s\n",
2196 					__func__, clk->name);
2197 	kref_put(&clk->ref, __clk_release);
2198 
2199 	clk_prepare_unlock();
2200 }
2201 EXPORT_SYMBOL_GPL(clk_unregister);
2202 
2203 static void devm_clk_release(struct device *dev, void *res)
2204 {
2205 	clk_unregister(*(struct clk **)res);
2206 }
2207 
2208 /**
2209  * devm_clk_register - resource managed clk_register()
2210  * @dev: device that is registering this clock
2211  * @hw: link to hardware-specific clock data
2212  *
2213  * Managed clk_register(). Clocks returned from this function are
2214  * automatically clk_unregister()ed on driver detach. See clk_register() for
2215  * more information.
2216  */
2217 struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
2218 {
2219 	struct clk *clk;
2220 	struct clk **clkp;
2221 
2222 	clkp = devres_alloc(devm_clk_release, sizeof(*clkp), GFP_KERNEL);
2223 	if (!clkp)
2224 		return ERR_PTR(-ENOMEM);
2225 
2226 	clk = clk_register(dev, hw);
2227 	if (!IS_ERR(clk)) {
2228 		*clkp = clk;
2229 		devres_add(dev, clkp);
2230 	} else {
2231 		devres_free(clkp);
2232 	}
2233 
2234 	return clk;
2235 }
2236 EXPORT_SYMBOL_GPL(devm_clk_register);
2237 
2238 static int devm_clk_match(struct device *dev, void *res, void *data)
2239 {
2240 	struct clk *c = res;
2241 	if (WARN_ON(!c))
2242 		return 0;
2243 	return c == data;
2244 }
2245 
2246 /**
2247  * devm_clk_unregister - resource managed clk_unregister()
2248  * @clk: clock to unregister
2249  *
2250  * Deallocate a clock allocated with devm_clk_register(). Normally
2251  * this function will not need to be called and the resource management
2252  * code will ensure that the resource is freed.
2253  */
2254 void devm_clk_unregister(struct device *dev, struct clk *clk)
2255 {
2256 	WARN_ON(devres_release(dev, devm_clk_release, devm_clk_match, clk));
2257 }
2258 EXPORT_SYMBOL_GPL(devm_clk_unregister);
2259 
2260 /*
2261  * clkdev helpers
2262  */
2263 int __clk_get(struct clk *clk)
2264 {
2265 	if (clk) {
2266 		if (!try_module_get(clk->owner))
2267 			return 0;
2268 
2269 		kref_get(&clk->ref);
2270 	}
2271 	return 1;
2272 }
2273 
2274 void __clk_put(struct clk *clk)
2275 {
2276 	if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
2277 		return;
2278 
2279 	clk_prepare_lock();
2280 	kref_put(&clk->ref, __clk_release);
2281 	clk_prepare_unlock();
2282 
2283 	module_put(clk->owner);
2284 }
2285 
2286 /***        clk rate change notifiers        ***/
2287 
2288 /**
2289  * clk_notifier_register - add a clk rate change notifier
2290  * @clk: struct clk * to watch
2291  * @nb: struct notifier_block * with callback info
2292  *
2293  * Request notification when clk's rate changes.  This uses an SRCU
2294  * notifier because we want it to block and notifier unregistrations are
2295  * uncommon.  The callbacks associated with the notifier must not
2296  * re-enter into the clk framework by calling any top-level clk APIs;
2297  * this will cause a nested prepare_lock mutex.
2298  *
2299  * In all notification cases cases (pre, post and abort rate change) the
2300  * original clock rate is passed to the callback via struct
2301  * clk_notifier_data.old_rate and the new frequency is passed via struct
2302  * clk_notifier_data.new_rate.
2303  *
2304  * clk_notifier_register() must be called from non-atomic context.
2305  * Returns -EINVAL if called with null arguments, -ENOMEM upon
2306  * allocation failure; otherwise, passes along the return value of
2307  * srcu_notifier_chain_register().
2308  */
2309 int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
2310 {
2311 	struct clk_notifier *cn;
2312 	int ret = -ENOMEM;
2313 
2314 	if (!clk || !nb)
2315 		return -EINVAL;
2316 
2317 	clk_prepare_lock();
2318 
2319 	/* search the list of notifiers for this clk */
2320 	list_for_each_entry(cn, &clk_notifier_list, node)
2321 		if (cn->clk == clk)
2322 			break;
2323 
2324 	/* if clk wasn't in the notifier list, allocate new clk_notifier */
2325 	if (cn->clk != clk) {
2326 		cn = kzalloc(sizeof(struct clk_notifier), GFP_KERNEL);
2327 		if (!cn)
2328 			goto out;
2329 
2330 		cn->clk = clk;
2331 		srcu_init_notifier_head(&cn->notifier_head);
2332 
2333 		list_add(&cn->node, &clk_notifier_list);
2334 	}
2335 
2336 	ret = srcu_notifier_chain_register(&cn->notifier_head, nb);
2337 
2338 	clk->notifier_count++;
2339 
2340 out:
2341 	clk_prepare_unlock();
2342 
2343 	return ret;
2344 }
2345 EXPORT_SYMBOL_GPL(clk_notifier_register);
2346 
2347 /**
2348  * clk_notifier_unregister - remove a clk rate change notifier
2349  * @clk: struct clk *
2350  * @nb: struct notifier_block * with callback info
2351  *
2352  * Request no further notification for changes to 'clk' and frees memory
2353  * allocated in clk_notifier_register.
2354  *
2355  * Returns -EINVAL if called with null arguments; otherwise, passes
2356  * along the return value of srcu_notifier_chain_unregister().
2357  */
2358 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
2359 {
2360 	struct clk_notifier *cn = NULL;
2361 	int ret = -EINVAL;
2362 
2363 	if (!clk || !nb)
2364 		return -EINVAL;
2365 
2366 	clk_prepare_lock();
2367 
2368 	list_for_each_entry(cn, &clk_notifier_list, node)
2369 		if (cn->clk == clk)
2370 			break;
2371 
2372 	if (cn->clk == clk) {
2373 		ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb);
2374 
2375 		clk->notifier_count--;
2376 
2377 		/* XXX the notifier code should handle this better */
2378 		if (!cn->notifier_head.head) {
2379 			srcu_cleanup_notifier_head(&cn->notifier_head);
2380 			list_del(&cn->node);
2381 			kfree(cn);
2382 		}
2383 
2384 	} else {
2385 		ret = -ENOENT;
2386 	}
2387 
2388 	clk_prepare_unlock();
2389 
2390 	return ret;
2391 }
2392 EXPORT_SYMBOL_GPL(clk_notifier_unregister);
2393 
2394 #ifdef CONFIG_OF
2395 /**
2396  * struct of_clk_provider - Clock provider registration structure
2397  * @link: Entry in global list of clock providers
2398  * @node: Pointer to device tree node of clock provider
2399  * @get: Get clock callback.  Returns NULL or a struct clk for the
2400  *       given clock specifier
2401  * @data: context pointer to be passed into @get callback
2402  */
2403 struct of_clk_provider {
2404 	struct list_head link;
2405 
2406 	struct device_node *node;
2407 	struct clk *(*get)(struct of_phandle_args *clkspec, void *data);
2408 	void *data;
2409 };
2410 
2411 static const struct of_device_id __clk_of_table_sentinel
2412 	__used __section(__clk_of_table_end);
2413 
2414 static LIST_HEAD(of_clk_providers);
2415 static DEFINE_MUTEX(of_clk_mutex);
2416 
2417 /* of_clk_provider list locking helpers */
2418 void of_clk_lock(void)
2419 {
2420 	mutex_lock(&of_clk_mutex);
2421 }
2422 
2423 void of_clk_unlock(void)
2424 {
2425 	mutex_unlock(&of_clk_mutex);
2426 }
2427 
2428 struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
2429 				     void *data)
2430 {
2431 	return data;
2432 }
2433 EXPORT_SYMBOL_GPL(of_clk_src_simple_get);
2434 
2435 struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data)
2436 {
2437 	struct clk_onecell_data *clk_data = data;
2438 	unsigned int idx = clkspec->args[0];
2439 
2440 	if (idx >= clk_data->clk_num) {
2441 		pr_err("%s: invalid clock index %d\n", __func__, idx);
2442 		return ERR_PTR(-EINVAL);
2443 	}
2444 
2445 	return clk_data->clks[idx];
2446 }
2447 EXPORT_SYMBOL_GPL(of_clk_src_onecell_get);
2448 
2449 /**
2450  * of_clk_add_provider() - Register a clock provider for a node
2451  * @np: Device node pointer associated with clock provider
2452  * @clk_src_get: callback for decoding clock
2453  * @data: context pointer for @clk_src_get callback.
2454  */
2455 int of_clk_add_provider(struct device_node *np,
2456 			struct clk *(*clk_src_get)(struct of_phandle_args *clkspec,
2457 						   void *data),
2458 			void *data)
2459 {
2460 	struct of_clk_provider *cp;
2461 	int ret;
2462 
2463 	cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL);
2464 	if (!cp)
2465 		return -ENOMEM;
2466 
2467 	cp->node = of_node_get(np);
2468 	cp->data = data;
2469 	cp->get = clk_src_get;
2470 
2471 	mutex_lock(&of_clk_mutex);
2472 	list_add(&cp->link, &of_clk_providers);
2473 	mutex_unlock(&of_clk_mutex);
2474 	pr_debug("Added clock from %s\n", np->full_name);
2475 
2476 	ret = of_clk_set_defaults(np, true);
2477 	if (ret < 0)
2478 		of_clk_del_provider(np);
2479 
2480 	return ret;
2481 }
2482 EXPORT_SYMBOL_GPL(of_clk_add_provider);
2483 
2484 /**
2485  * of_clk_del_provider() - Remove a previously registered clock provider
2486  * @np: Device node pointer associated with clock provider
2487  */
2488 void of_clk_del_provider(struct device_node *np)
2489 {
2490 	struct of_clk_provider *cp;
2491 
2492 	mutex_lock(&of_clk_mutex);
2493 	list_for_each_entry(cp, &of_clk_providers, link) {
2494 		if (cp->node == np) {
2495 			list_del(&cp->link);
2496 			of_node_put(cp->node);
2497 			kfree(cp);
2498 			break;
2499 		}
2500 	}
2501 	mutex_unlock(&of_clk_mutex);
2502 }
2503 EXPORT_SYMBOL_GPL(of_clk_del_provider);
2504 
2505 struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec)
2506 {
2507 	struct of_clk_provider *provider;
2508 	struct clk *clk = ERR_PTR(-EPROBE_DEFER);
2509 
2510 	/* Check if we have such a provider in our array */
2511 	list_for_each_entry(provider, &of_clk_providers, link) {
2512 		if (provider->node == clkspec->np)
2513 			clk = provider->get(clkspec, provider->data);
2514 		if (!IS_ERR(clk))
2515 			break;
2516 	}
2517 
2518 	return clk;
2519 }
2520 
2521 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
2522 {
2523 	struct clk *clk;
2524 
2525 	mutex_lock(&of_clk_mutex);
2526 	clk = __of_clk_get_from_provider(clkspec);
2527 	mutex_unlock(&of_clk_mutex);
2528 
2529 	return clk;
2530 }
2531 
2532 int of_clk_get_parent_count(struct device_node *np)
2533 {
2534 	return of_count_phandle_with_args(np, "clocks", "#clock-cells");
2535 }
2536 EXPORT_SYMBOL_GPL(of_clk_get_parent_count);
2537 
2538 const char *of_clk_get_parent_name(struct device_node *np, int index)
2539 {
2540 	struct of_phandle_args clkspec;
2541 	struct property *prop;
2542 	const char *clk_name;
2543 	const __be32 *vp;
2544 	u32 pv;
2545 	int rc;
2546 	int count;
2547 
2548 	if (index < 0)
2549 		return NULL;
2550 
2551 	rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
2552 					&clkspec);
2553 	if (rc)
2554 		return NULL;
2555 
2556 	index = clkspec.args_count ? clkspec.args[0] : 0;
2557 	count = 0;
2558 
2559 	/* if there is an indices property, use it to transfer the index
2560 	 * specified into an array offset for the clock-output-names property.
2561 	 */
2562 	of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) {
2563 		if (index == pv) {
2564 			index = count;
2565 			break;
2566 		}
2567 		count++;
2568 	}
2569 
2570 	if (of_property_read_string_index(clkspec.np, "clock-output-names",
2571 					  index,
2572 					  &clk_name) < 0)
2573 		clk_name = clkspec.np->name;
2574 
2575 	of_node_put(clkspec.np);
2576 	return clk_name;
2577 }
2578 EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
2579 
2580 struct clock_provider {
2581 	of_clk_init_cb_t clk_init_cb;
2582 	struct device_node *np;
2583 	struct list_head node;
2584 };
2585 
2586 static LIST_HEAD(clk_provider_list);
2587 
2588 /*
2589  * This function looks for a parent clock. If there is one, then it
2590  * checks that the provider for this parent clock was initialized, in
2591  * this case the parent clock will be ready.
2592  */
2593 static int parent_ready(struct device_node *np)
2594 {
2595 	int i = 0;
2596 
2597 	while (true) {
2598 		struct clk *clk = of_clk_get(np, i);
2599 
2600 		/* this parent is ready we can check the next one */
2601 		if (!IS_ERR(clk)) {
2602 			clk_put(clk);
2603 			i++;
2604 			continue;
2605 		}
2606 
2607 		/* at least one parent is not ready, we exit now */
2608 		if (PTR_ERR(clk) == -EPROBE_DEFER)
2609 			return 0;
2610 
2611 		/*
2612 		 * Here we make assumption that the device tree is
2613 		 * written correctly. So an error means that there is
2614 		 * no more parent. As we didn't exit yet, then the
2615 		 * previous parent are ready. If there is no clock
2616 		 * parent, no need to wait for them, then we can
2617 		 * consider their absence as being ready
2618 		 */
2619 		return 1;
2620 	}
2621 }
2622 
2623 /**
2624  * of_clk_init() - Scan and init clock providers from the DT
2625  * @matches: array of compatible values and init functions for providers.
2626  *
2627  * This function scans the device tree for matching clock providers
2628  * and calls their initialization functions. It also does it by trying
2629  * to follow the dependencies.
2630  */
2631 void __init of_clk_init(const struct of_device_id *matches)
2632 {
2633 	const struct of_device_id *match;
2634 	struct device_node *np;
2635 	struct clock_provider *clk_provider, *next;
2636 	bool is_init_done;
2637 	bool force = false;
2638 
2639 	if (!matches)
2640 		matches = &__clk_of_table;
2641 
2642 	/* First prepare the list of the clocks providers */
2643 	for_each_matching_node_and_match(np, matches, &match) {
2644 		struct clock_provider *parent =
2645 			kzalloc(sizeof(struct clock_provider),	GFP_KERNEL);
2646 
2647 		parent->clk_init_cb = match->data;
2648 		parent->np = np;
2649 		list_add_tail(&parent->node, &clk_provider_list);
2650 	}
2651 
2652 	while (!list_empty(&clk_provider_list)) {
2653 		is_init_done = false;
2654 		list_for_each_entry_safe(clk_provider, next,
2655 					&clk_provider_list, node) {
2656 			if (force || parent_ready(clk_provider->np)) {
2657 
2658 				clk_provider->clk_init_cb(clk_provider->np);
2659 				of_clk_set_defaults(clk_provider->np, true);
2660 
2661 				list_del(&clk_provider->node);
2662 				kfree(clk_provider);
2663 				is_init_done = true;
2664 			}
2665 		}
2666 
2667 		/*
2668 		 * We didn't manage to initialize any of the
2669 		 * remaining providers during the last loop, so now we
2670 		 * initialize all the remaining ones unconditionally
2671 		 * in case the clock parent was not mandatory
2672 		 */
2673 		if (!is_init_done)
2674 			force = true;
2675 	}
2676 }
2677 #endif
2678