1/*
2 * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
3 * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
4 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Adjustable divider clock implementation
11 */
12
13#include <linux/clk-provider.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <linux/io.h>
17#include <linux/err.h>
18#include <linux/string.h>
19#include <linux/log2.h>
20
21/*
22 * DOC: basic adjustable divider clock that cannot gate
23 *
24 * Traits of this clock:
25 * prepare - clk_prepare only ensures that parents are prepared
26 * enable - clk_enable only ensures that parents are enabled
27 * rate - rate is adjustable.  clk->rate = DIV_ROUND_UP(parent->rate / divisor)
28 * parent - fixed parent.  No clk_set_parent support
29 */
30
31#define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
32
33#define div_mask(width)	((1 << (width)) - 1)
34
35static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
36{
37	unsigned int maxdiv = 0;
38	const struct clk_div_table *clkt;
39
40	for (clkt = table; clkt->div; clkt++)
41		if (clkt->div > maxdiv)
42			maxdiv = clkt->div;
43	return maxdiv;
44}
45
46static unsigned int _get_table_mindiv(const struct clk_div_table *table)
47{
48	unsigned int mindiv = UINT_MAX;
49	const struct clk_div_table *clkt;
50
51	for (clkt = table; clkt->div; clkt++)
52		if (clkt->div < mindiv)
53			mindiv = clkt->div;
54	return mindiv;
55}
56
57static unsigned int _get_maxdiv(const struct clk_div_table *table, u8 width,
58				unsigned long flags)
59{
60	if (flags & CLK_DIVIDER_ONE_BASED)
61		return div_mask(width);
62	if (flags & CLK_DIVIDER_POWER_OF_TWO)
63		return 1 << div_mask(width);
64	if (table)
65		return _get_table_maxdiv(table);
66	return div_mask(width) + 1;
67}
68
69static unsigned int _get_table_div(const struct clk_div_table *table,
70							unsigned int val)
71{
72	const struct clk_div_table *clkt;
73
74	for (clkt = table; clkt->div; clkt++)
75		if (clkt->val == val)
76			return clkt->div;
77	return 0;
78}
79
80static unsigned int _get_div(const struct clk_div_table *table,
81			     unsigned int val, unsigned long flags)
82{
83	if (flags & CLK_DIVIDER_ONE_BASED)
84		return val;
85	if (flags & CLK_DIVIDER_POWER_OF_TWO)
86		return 1 << val;
87	if (table)
88		return _get_table_div(table, val);
89	return val + 1;
90}
91
92static unsigned int _get_table_val(const struct clk_div_table *table,
93							unsigned int div)
94{
95	const struct clk_div_table *clkt;
96
97	for (clkt = table; clkt->div; clkt++)
98		if (clkt->div == div)
99			return clkt->val;
100	return 0;
101}
102
103static unsigned int _get_val(const struct clk_div_table *table,
104			     unsigned int div, unsigned long flags)
105{
106	if (flags & CLK_DIVIDER_ONE_BASED)
107		return div;
108	if (flags & CLK_DIVIDER_POWER_OF_TWO)
109		return __ffs(div);
110	if (table)
111		return  _get_table_val(table, div);
112	return div - 1;
113}
114
115unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
116				  unsigned int val,
117				  const struct clk_div_table *table,
118				  unsigned long flags)
119{
120	unsigned int div;
121
122	div = _get_div(table, val, flags);
123	if (!div) {
124		WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
125			"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
126			__clk_get_name(hw->clk));
127		return parent_rate;
128	}
129
130	return DIV_ROUND_UP(parent_rate, div);
131}
132EXPORT_SYMBOL_GPL(divider_recalc_rate);
133
134static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
135		unsigned long parent_rate)
136{
137	struct clk_divider *divider = to_clk_divider(hw);
138	unsigned int val;
139
140	val = clk_readl(divider->reg) >> divider->shift;
141	val &= div_mask(divider->width);
142
143	return divider_recalc_rate(hw, parent_rate, val, divider->table,
144				   divider->flags);
145}
146
147static bool _is_valid_table_div(const struct clk_div_table *table,
148							 unsigned int div)
149{
150	const struct clk_div_table *clkt;
151
152	for (clkt = table; clkt->div; clkt++)
153		if (clkt->div == div)
154			return true;
155	return false;
156}
157
158static bool _is_valid_div(const struct clk_div_table *table, unsigned int div,
159			  unsigned long flags)
160{
161	if (flags & CLK_DIVIDER_POWER_OF_TWO)
162		return is_power_of_2(div);
163	if (table)
164		return _is_valid_table_div(table, div);
165	return true;
166}
167
168static int _round_up_table(const struct clk_div_table *table, int div)
169{
170	const struct clk_div_table *clkt;
171	int up = INT_MAX;
172
173	for (clkt = table; clkt->div; clkt++) {
174		if (clkt->div == div)
175			return clkt->div;
176		else if (clkt->div < div)
177			continue;
178
179		if ((clkt->div - div) < (up - div))
180			up = clkt->div;
181	}
182
183	return up;
184}
185
186static int _round_down_table(const struct clk_div_table *table, int div)
187{
188	const struct clk_div_table *clkt;
189	int down = _get_table_mindiv(table);
190
191	for (clkt = table; clkt->div; clkt++) {
192		if (clkt->div == div)
193			return clkt->div;
194		else if (clkt->div > div)
195			continue;
196
197		if ((div - clkt->div) < (div - down))
198			down = clkt->div;
199	}
200
201	return down;
202}
203
204static int _div_round_up(const struct clk_div_table *table,
205			 unsigned long parent_rate, unsigned long rate,
206			 unsigned long flags)
207{
208	int div = DIV_ROUND_UP(parent_rate, rate);
209
210	if (flags & CLK_DIVIDER_POWER_OF_TWO)
211		div = __roundup_pow_of_two(div);
212	if (table)
213		div = _round_up_table(table, div);
214
215	return div;
216}
217
218static int _div_round_closest(const struct clk_div_table *table,
219			      unsigned long parent_rate, unsigned long rate,
220			      unsigned long flags)
221{
222	int up, down;
223	unsigned long up_rate, down_rate;
224
225	up = DIV_ROUND_UP(parent_rate, rate);
226	down = parent_rate / rate;
227
228	if (flags & CLK_DIVIDER_POWER_OF_TWO) {
229		up = __roundup_pow_of_two(up);
230		down = __rounddown_pow_of_two(down);
231	} else if (table) {
232		up = _round_up_table(table, up);
233		down = _round_down_table(table, down);
234	}
235
236	up_rate = DIV_ROUND_UP(parent_rate, up);
237	down_rate = DIV_ROUND_UP(parent_rate, down);
238
239	return (rate - up_rate) <= (down_rate - rate) ? up : down;
240}
241
242static int _div_round(const struct clk_div_table *table,
243		      unsigned long parent_rate, unsigned long rate,
244		      unsigned long flags)
245{
246	if (flags & CLK_DIVIDER_ROUND_CLOSEST)
247		return _div_round_closest(table, parent_rate, rate, flags);
248
249	return _div_round_up(table, parent_rate, rate, flags);
250}
251
252static bool _is_best_div(unsigned long rate, unsigned long now,
253			 unsigned long best, unsigned long flags)
254{
255	if (flags & CLK_DIVIDER_ROUND_CLOSEST)
256		return abs(rate - now) < abs(rate - best);
257
258	return now <= rate && now > best;
259}
260
261static int _next_div(const struct clk_div_table *table, int div,
262		     unsigned long flags)
263{
264	div++;
265
266	if (flags & CLK_DIVIDER_POWER_OF_TWO)
267		return __roundup_pow_of_two(div);
268	if (table)
269		return _round_up_table(table, div);
270
271	return div;
272}
273
274static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
275			       unsigned long *best_parent_rate,
276			       const struct clk_div_table *table, u8 width,
277			       unsigned long flags)
278{
279	int i, bestdiv = 0;
280	unsigned long parent_rate, best = 0, now, maxdiv;
281	unsigned long parent_rate_saved = *best_parent_rate;
282
283	if (!rate)
284		rate = 1;
285
286	maxdiv = _get_maxdiv(table, width, flags);
287
288	if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
289		parent_rate = *best_parent_rate;
290		bestdiv = _div_round(table, parent_rate, rate, flags);
291		bestdiv = bestdiv == 0 ? 1 : bestdiv;
292		bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
293		return bestdiv;
294	}
295
296	/*
297	 * The maximum divider we can use without overflowing
298	 * unsigned long in rate * i below
299	 */
300	maxdiv = min(ULONG_MAX / rate, maxdiv);
301
302	for (i = 1; i <= maxdiv; i = _next_div(table, i, flags)) {
303		if (!_is_valid_div(table, i, flags))
304			continue;
305		if (rate * i == parent_rate_saved) {
306			/*
307			 * It's the most ideal case if the requested rate can be
308			 * divided from parent clock without needing to change
309			 * parent rate, so return the divider immediately.
310			 */
311			*best_parent_rate = parent_rate_saved;
312			return i;
313		}
314		parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
315					       rate * i);
316		now = DIV_ROUND_UP(parent_rate, i);
317		if (_is_best_div(rate, now, best, flags)) {
318			bestdiv = i;
319			best = now;
320			*best_parent_rate = parent_rate;
321		}
322	}
323
324	if (!bestdiv) {
325		bestdiv = _get_maxdiv(table, width, flags);
326		*best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
327	}
328
329	return bestdiv;
330}
331
332long divider_round_rate(struct clk_hw *hw, unsigned long rate,
333			unsigned long *prate, const struct clk_div_table *table,
334			u8 width, unsigned long flags)
335{
336	int div;
337
338	div = clk_divider_bestdiv(hw, rate, prate, table, width, flags);
339
340	return DIV_ROUND_UP(*prate, div);
341}
342EXPORT_SYMBOL_GPL(divider_round_rate);
343
344static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
345				unsigned long *prate)
346{
347	struct clk_divider *divider = to_clk_divider(hw);
348	int bestdiv;
349
350	/* if read only, just return current value */
351	if (divider->flags & CLK_DIVIDER_READ_ONLY) {
352		bestdiv = readl(divider->reg) >> divider->shift;
353		bestdiv &= div_mask(divider->width);
354		bestdiv = _get_div(divider->table, bestdiv, divider->flags);
355		return DIV_ROUND_UP(*prate, bestdiv);
356	}
357
358	return divider_round_rate(hw, rate, prate, divider->table,
359				  divider->width, divider->flags);
360}
361
362int divider_get_val(unsigned long rate, unsigned long parent_rate,
363		    const struct clk_div_table *table, u8 width,
364		    unsigned long flags)
365{
366	unsigned int div, value;
367
368	div = DIV_ROUND_UP(parent_rate, rate);
369
370	if (!_is_valid_div(table, div, flags))
371		return -EINVAL;
372
373	value = _get_val(table, div, flags);
374
375	return min_t(unsigned int, value, div_mask(width));
376}
377EXPORT_SYMBOL_GPL(divider_get_val);
378
379static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
380				unsigned long parent_rate)
381{
382	struct clk_divider *divider = to_clk_divider(hw);
383	unsigned int value;
384	unsigned long flags = 0;
385	u32 val;
386
387	value = divider_get_val(rate, parent_rate, divider->table,
388				divider->width, divider->flags);
389
390	if (divider->lock)
391		spin_lock_irqsave(divider->lock, flags);
392
393	if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
394		val = div_mask(divider->width) << (divider->shift + 16);
395	} else {
396		val = clk_readl(divider->reg);
397		val &= ~(div_mask(divider->width) << divider->shift);
398	}
399	val |= value << divider->shift;
400	clk_writel(val, divider->reg);
401
402	if (divider->lock)
403		spin_unlock_irqrestore(divider->lock, flags);
404
405	return 0;
406}
407
408const struct clk_ops clk_divider_ops = {
409	.recalc_rate = clk_divider_recalc_rate,
410	.round_rate = clk_divider_round_rate,
411	.set_rate = clk_divider_set_rate,
412};
413EXPORT_SYMBOL_GPL(clk_divider_ops);
414
415static struct clk *_register_divider(struct device *dev, const char *name,
416		const char *parent_name, unsigned long flags,
417		void __iomem *reg, u8 shift, u8 width,
418		u8 clk_divider_flags, const struct clk_div_table *table,
419		spinlock_t *lock)
420{
421	struct clk_divider *div;
422	struct clk *clk;
423	struct clk_init_data init;
424
425	if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
426		if (width + shift > 16) {
427			pr_warn("divider value exceeds LOWORD field\n");
428			return ERR_PTR(-EINVAL);
429		}
430	}
431
432	/* allocate the divider */
433	div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
434	if (!div) {
435		pr_err("%s: could not allocate divider clk\n", __func__);
436		return ERR_PTR(-ENOMEM);
437	}
438
439	init.name = name;
440	init.ops = &clk_divider_ops;
441	init.flags = flags | CLK_IS_BASIC;
442	init.parent_names = (parent_name ? &parent_name: NULL);
443	init.num_parents = (parent_name ? 1 : 0);
444
445	/* struct clk_divider assignments */
446	div->reg = reg;
447	div->shift = shift;
448	div->width = width;
449	div->flags = clk_divider_flags;
450	div->lock = lock;
451	div->hw.init = &init;
452	div->table = table;
453
454	/* register the clock */
455	clk = clk_register(dev, &div->hw);
456
457	if (IS_ERR(clk))
458		kfree(div);
459
460	return clk;
461}
462
463/**
464 * clk_register_divider - register a divider clock with the clock framework
465 * @dev: device registering this clock
466 * @name: name of this clock
467 * @parent_name: name of clock's parent
468 * @flags: framework-specific flags
469 * @reg: register address to adjust divider
470 * @shift: number of bits to shift the bitfield
471 * @width: width of the bitfield
472 * @clk_divider_flags: divider-specific flags for this clock
473 * @lock: shared register lock for this clock
474 */
475struct clk *clk_register_divider(struct device *dev, const char *name,
476		const char *parent_name, unsigned long flags,
477		void __iomem *reg, u8 shift, u8 width,
478		u8 clk_divider_flags, spinlock_t *lock)
479{
480	return _register_divider(dev, name, parent_name, flags, reg, shift,
481			width, clk_divider_flags, NULL, lock);
482}
483EXPORT_SYMBOL_GPL(clk_register_divider);
484
485/**
486 * clk_register_divider_table - register a table based divider clock with
487 * the clock framework
488 * @dev: device registering this clock
489 * @name: name of this clock
490 * @parent_name: name of clock's parent
491 * @flags: framework-specific flags
492 * @reg: register address to adjust divider
493 * @shift: number of bits to shift the bitfield
494 * @width: width of the bitfield
495 * @clk_divider_flags: divider-specific flags for this clock
496 * @table: array of divider/value pairs ending with a div set to 0
497 * @lock: shared register lock for this clock
498 */
499struct clk *clk_register_divider_table(struct device *dev, const char *name,
500		const char *parent_name, unsigned long flags,
501		void __iomem *reg, u8 shift, u8 width,
502		u8 clk_divider_flags, const struct clk_div_table *table,
503		spinlock_t *lock)
504{
505	return _register_divider(dev, name, parent_name, flags, reg, shift,
506			width, clk_divider_flags, table, lock);
507}
508EXPORT_SYMBOL_GPL(clk_register_divider_table);
509
510void clk_unregister_divider(struct clk *clk)
511{
512	struct clk_divider *div;
513	struct clk_hw *hw;
514
515	hw = __clk_get_hw(clk);
516	if (!hw)
517		return;
518
519	div = to_clk_divider(hw);
520
521	clk_unregister(clk);
522	kfree(div);
523}
524EXPORT_SYMBOL_GPL(clk_unregister_divider);
525