aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/clk/clk-divider.c
blob: db7f8bce7467a2abfd37f6ccb8e22c784a6bce28 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
/*
 * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
 * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Adjustable divider clock implementation
 */

#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/log2.h>

/*
 * DOC: basic adjustable divider clock that cannot gate
 *
 * Traits of this clock:
 * prepare - clk_prepare only ensures that parents are prepared
 * enable - clk_enable only ensures that parents are enabled
 * rate - rate is adjustable.  clk->rate = DIV_ROUND_UP(parent->rate / divisor)
 * parent - fixed parent.  No clk_set_parent support
 */

#define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)

#define div_mask(width)	((1 << (width)) - 1)

static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
{
	unsigned int maxdiv = 0;
	const struct clk_div_table *clkt;

	for (clkt = table; clkt->div; clkt++)
		if (clkt->div > maxdiv)
			maxdiv = clkt->div;
	return maxdiv;
}

static unsigned int _get_table_mindiv(const struct clk_div_table *table)
{
	unsigned int mindiv = UINT_MAX;
	const struct clk_div_table *clkt;

	for (clkt = table; clkt->div; clkt++)
		if (clkt->div < mindiv)
			mindiv = clkt->div;
	return mindiv;
}

static unsigned int _get_maxdiv(const struct clk_div_table *table, u8 width,
				unsigned long flags)
{
	if (flags & CLK_DIVIDER_ONE_BASED)
		return div_mask(width);
	if (flags & CLK_DIVIDER_POWER_OF_TWO)
		return 1 << div_mask(width);
	if (table)
		return _get_table_maxdiv(table);
	return div_mask(width) + 1;
}

static unsigned int _get_table_div(const struct clk_div_table *table,
							unsigned int val)
{
	const struct clk_div_table *clkt;

	for (clkt = table; clkt->div; clkt++)
		if (clkt->val == val)
			return clkt->div;
	return 0;
}

static unsigned int _get_div(const struct clk_div_table *table,
			     unsigned int val, unsigned long flags)
{
	if (flags & CLK_DIVIDER_ONE_BASED)
		return val;
	if (flags & CLK_DIVIDER_POWER_OF_TWO)
		return 1 << val;
	if (table)
		return _get_table_div(table, val);
	return val + 1;
}

static unsigned int _get_table_val(const struct clk_div_table *table,
							unsigned int div)
{
	const struct clk_div_table *clkt;

	for (clkt = table; clkt->div; clkt++)
		if (clkt->div == div)
			return clkt->val;
	return 0;
}

static unsigned int _get_val(const struct clk_div_table *table,
			     unsigned int div, unsigned long flags)
{
	if (flags & CLK_DIVIDER_ONE_BASED)
		return div;
	if (flags & CLK_DIVIDER_POWER_OF_TWO)
		return __ffs(div);
	if (table)
		return  _get_table_val(table, div);
	return div - 1;
}

unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
				  unsigned int val,
				  const struct clk_div_table *table,
				  unsigned long flags)
{
	unsigned int div;

	div = _get_div(table, val, flags);
	if (!div) {
		WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
			"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
			__clk_get_name(hw->clk));
		return parent_rate;
	}

	return DIV_ROUND_UP(parent_rate, div);
}
EXPORT_SYMBOL_GPL(divider_recalc_rate);

static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	struct clk_divider *divider = to_clk_divider(hw);
	unsigned int val;

	val = clk_readl(divider->reg) >> divider->shift;
	val &= div_mask(divider->width);

	return divider_recalc_rate(hw, parent_rate, val, divider->table,
				   divider->flags);
}

/*
 * The reverse of DIV_ROUND_UP: The maximum number which
 * divided by m is r
 */
#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)

static bool _is_valid_table_div(const struct clk_div_table *table,
							 unsigned int div)
{
	const struct clk_div_table *clkt;

	for (clkt = table; clkt->div; clkt++)
		if (clkt->div == div)
			return true;
	return false;
}

static bool _is_valid_div(const struct clk_div_table *table, unsigned int div,
			  unsigned long flags)
{
	if (flags & CLK_DIVIDER_POWER_OF_TWO)
		return is_power_of_2(div);
	if (table)
		return _is_valid_table_div(table, div);
	return true;
}

static int _round_up_table(const struct clk_div_table *table, int div)
{
	const struct clk_div_table *clkt;
	int up = INT_MAX;

	for (clkt = table; clkt->div; clkt++) {
		if (clkt->div == div)
			return clkt->div;
		else if (clkt->div < div)
			continue;

		if ((clkt->div - div) < (up - div))
			up = clkt->div;
	}

	return up;
}

static int _round_down_table(const struct clk_div_table *table, int div)
{
	const struct clk_div_table *clkt;
	int down = _get_table_mindiv(table);

	for (clkt = table; clkt->div; clkt++) {
		if (clkt->div == div)
			return clkt->div;
		else if (clkt->div > div)
			continue;

		if ((div - clkt->div) < (div - down))
			down = clkt->div;
	}

	return down;
}

static int _div_round_up(const struct clk_div_table *table,
			 unsigned long parent_rate, unsigned long rate,
			 unsigned long flags)
{
	int div = DIV_ROUND_UP(parent_rate, rate);

	if (flags & CLK_DIVIDER_POWER_OF_TWO)
		div = __roundup_pow_of_two(div);
	if (table)
		div = _round_up_table(table, div);

	return div;
}

static int _div_round_closest(const struct clk_div_table *table,
			      unsigned long parent_rate, unsigned long rate,
			      unsigned long flags)
{
	int up, down, div;

	up = down = div = DIV_ROUND_CLOSEST(parent_rate, rate);

	if (flags & CLK_DIVIDER_POWER_OF_TWO) {
		up = __roundup_pow_of_two(div);
		down = __rounddown_pow_of_two(div);
	} else if (table) {
		up = _round_up_table(table, div);
		down = _round_down_table(table, div);
	}

	return (up - div) <= (div - down) ? up : down;
}

static int _div_round(const struct clk_div_table *table,
		      unsigned long parent_rate, unsigned long rate,
		      unsigned long flags)
{
	if (flags & CLK_DIVIDER_ROUND_CLOSEST)
		return _div_round_closest(table, parent_rate, rate, flags);

	return _div_round_up(table, parent_rate, rate, flags);
}

static bool _is_best_div(unsigned long rate, unsigned long now,
			 unsigned long best, unsigned long flags)
{
	if (flags & CLK_DIVIDER_ROUND_CLOSEST)
		return abs(rate - now) < abs(rate - best);

	return now <= rate && now > best;
}

static int _next_div(const struct clk_div_table *table, int div,
		     unsigned long flags)
{
	div++;

	if (flags & CLK_DIVIDER_POWER_OF_TWO)
		return __roundup_pow_of_two(div);
	if (table)
		return _round_up_table(table, div);

	return div;
}

static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
			       unsigned long *best_parent_rate,
			       const struct clk_div_table *table, u8 width,
			       unsigned long flags)
{
	int i, bestdiv = 0;
	unsigned long parent_rate, best = 0, now, maxdiv;
	unsigned long parent_rate_saved = *best_parent_rate;

	if (!rate)
		rate = 1;

	maxdiv = _get_maxdiv(table, width, flags);

	if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
		parent_rate = *best_parent_rate;
		bestdiv = _div_round(table, parent_rate, rate, flags);
		bestdiv = bestdiv == 0 ? 1 : bestdiv;
		bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
		return bestdiv;
	}

	/*
	 * The maximum divider we can use without overflowing
	 * unsigned long in rate * i below
	 */
	maxdiv = min(ULONG_MAX / rate, maxdiv);

	for (i = 1; i <= maxdiv; i = _next_div(table, i, flags)) {
		if (!_is_valid_div(table, i, flags))
			continue;
		if (rate * i == parent_rate_saved) {
			/*
			 * It's the most ideal case if the requested rate can be
			 * divided from parent clock without needing to change
			 * parent rate, so return the divider immediately.
			 */
			*best_parent_rate = parent_rate_saved;
			return i;
		}
		parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
				MULT_ROUND_UP(rate, i));
		now = DIV_ROUND_UP(parent_rate, i);
		if (_is_best_div(rate, now, best, flags)) {
			bestdiv = i;
			best = now;
			*best_parent_rate = parent_rate;
		}
	}

	if (!bestdiv) {
		bestdiv = _get_maxdiv(table, width, flags);
		*best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
	}

	return bestdiv;
}

long divider_round_rate(struct clk_hw *hw, unsigned long rate,
			unsigned long *prate, const struct clk_div_table *table,
			u8 width, unsigned long flags)
{
	int div;

	div = clk_divider_bestdiv(hw, rate, prate, table, width, flags);

	return DIV_ROUND_UP(*prate, div);
}
EXPORT_SYMBOL_GPL(divider_round_rate);

static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
				unsigned long *prate)
{
	struct clk_divider *divider = to_clk_divider(hw);
	int bestdiv;

	/* if read only, just return current value */
	if (divider->flags & CLK_DIVIDER_READ_ONLY) {
		bestdiv = readl(divider->reg) >> divider->shift;
		bestdiv &= div_mask(divider->width);
		bestdiv = _get_div(divider->table, bestdiv, divider->flags);
		return bestdiv;
	}

	return divider_round_rate(hw, rate, prate, divider->table,
				  divider->width, divider->flags);
}

int divider_get_val(unsigned long rate, unsigned long parent_rate,
		    const struct clk_div_table *table, u8 width,
		    unsigned long flags)
{
	unsigned int div, value;

	div = DIV_ROUND_UP(parent_rate, rate);

	if (!_is_valid_div(table, div, flags))
		return -EINVAL;

	value = _get_val(table, div, flags);

	return min_t(unsigned int, value, div_mask(width));
}
EXPORT_SYMBOL_GPL(divider_get_val);

static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
				unsigned long parent_rate)
{
	struct clk_divider *divider = to_clk_divider(hw);
	unsigned int value;
	unsigned long flags = 0;
	u32 val;

	value = divider_get_val(rate, parent_rate, divider->table,
				divider->width, divider->flags);

	if (divider->lock)
		spin_lock_irqsave(divider->lock, flags);

	if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
		val = div_mask(divider->width) << (divider->shift + 16);
	} else {
		val = clk_readl(divider->reg);
		val &= ~(div_mask(divider->width) << divider->shift);
	}
	val |= value << divider->shift;
	clk_writel(val, divider->reg);

	if (divider->lock)
		spin_unlock_irqrestore(divider->lock, flags);

	return 0;
}

const struct clk_ops clk_divider_ops = {
	.recalc_rate = clk_divider_recalc_rate,
	.round_rate = clk_divider_round_rate,
	.set_rate = clk_divider_set_rate,
};
EXPORT_SYMBOL_GPL(clk_divider_ops);

static struct clk *_register_divider(struct device *dev, const char *name,
		const char *parent_name, unsigned long flags,
		void __iomem *reg, u8 shift, u8 width,
		u8 clk_divider_flags, const struct clk_div_table *table,
		spinlock_t *lock)
{
	struct clk_divider *div;
	struct clk *clk;
	struct clk_init_data init;

	if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
		if (width + shift > 16) {
			pr_warn("divider value exceeds LOWORD field\n");
			return ERR_PTR(-EINVAL);
		}
	}

	/* allocate the divider */
	div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
	if (!div) {
		pr_err("%s: could not allocate divider clk\n", __func__);
		return ERR_PTR(-ENOMEM);
	}

	init.name = name;
	init.ops = &clk_divider_ops;
	init.flags = flags | CLK_IS_BASIC;
	init.parent_names = (parent_name ? &parent_name: NULL);
	init.num_parents = (parent_name ? 1 : 0);

	/* struct clk_divider assignments */
	div->reg = reg;
	div->shift = shift;
	div->width = width;
	div->flags = clk_divider_flags;
	div->lock = lock;
	div->hw.init = &init;
	div->table = table;

	/* register the clock */
	clk = clk_register(dev, &div->hw);

	if (IS_ERR(clk))
		kfree(div);

	return clk;
}

/**
 * clk_register_divider - register a divider clock with the clock framework
 * @dev: device registering this clock
 * @name: name of this clock
 * @parent_name: name of clock's parent
 * @flags: framework-specific flags
 * @reg: register address to adjust divider
 * @shift: number of bits to shift the bitfield
 * @width: width of the bitfield
 * @clk_divider_flags: divider-specific flags for this clock
 * @lock: shared register lock for this clock
 */
struct clk *clk_register_divider(struct device *dev, const char *name,
		const char *parent_name, unsigned long flags,
		void __iomem *reg, u8 shift, u8 width,
		u8 clk_divider_flags, spinlock_t *lock)
{
	return _register_divider(dev, name, parent_name, flags, reg, shift,
			width, clk_divider_flags, NULL, lock);
}
EXPORT_SYMBOL_GPL(clk_register_divider);

/**
 * clk_register_divider_table - register a table based divider clock with
 * the clock framework
 * @dev: device registering this clock
 * @name: name of this clock
 * @parent_name: name of clock's parent
 * @flags: framework-specific flags
 * @reg: register address to adjust divider
 * @shift: number of bits to shift the bitfield
 * @width: width of the bitfield
 * @clk_divider_flags: divider-specific flags for this clock
 * @table: array of divider/value pairs ending with a div set to 0
 * @lock: shared register lock for this clock
 */
struct clk *clk_register_divider_table(struct device *dev, const char *name,
		const char *parent_name, unsigned long flags,
		void __iomem *reg, u8 shift, u8 width,
		u8 clk_divider_flags, const struct clk_div_table *table,
		spinlock_t *lock)
{
	return _register_divider(dev, name, parent_name, flags, reg, shift,
			width, clk_divider_flags, table, lock);
}
EXPORT_SYMBOL_GPL(clk_register_divider_table);

void clk_unregister_divider(struct clk *clk)
{
	struct clk_divider *div;
	struct clk_hw *hw;

	hw = __clk_get_hw(clk);
	if (!hw)
		return;

	div = to_clk_divider(hw);

	clk_unregister(clk);
	kfree(div);
}
EXPORT_SYMBOL_GPL(clk_unregister_divider);