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>
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.
10 * Adjustable divider clock implementation
13 #include <linux/clk-provider.h>
14 #include <linux/module.h>
15 #include <linux/slab.h>
17 #include <linux/err.h>
18 #include <linux/string.h>
19 #include <linux/log2.h>
22 * DOC: basic adjustable divider clock that cannot gate
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 = ceiling(parent->rate / divisor)
28 * parent - fixed parent. No clk_set_parent support
31 #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
33 #define div_mask(width) ((1 << (width)) - 1)
35 static unsigned int _get_table_maxdiv(const struct clk_div_table *table,
38 unsigned int maxdiv = 0, mask = div_mask(width);
39 const struct clk_div_table *clkt;
41 for (clkt = table; clkt->div; clkt++)
42 if (clkt->div > maxdiv && clkt->val <= mask)
47 static unsigned int _get_table_mindiv(const struct clk_div_table *table)
49 unsigned int mindiv = UINT_MAX;
50 const struct clk_div_table *clkt;
52 for (clkt = table; clkt->div; clkt++)
53 if (clkt->div < mindiv)
58 static unsigned int _get_maxdiv(const struct clk_div_table *table, u8 width,
61 if (flags & CLK_DIVIDER_ONE_BASED)
62 return div_mask(width);
63 if (flags & CLK_DIVIDER_POWER_OF_TWO)
64 return 1 << div_mask(width);
66 return _get_table_maxdiv(table, width);
67 return div_mask(width) + 1;
70 static unsigned int _get_table_div(const struct clk_div_table *table,
73 const struct clk_div_table *clkt;
75 for (clkt = table; clkt->div; clkt++)
81 static unsigned int _get_div(const struct clk_div_table *table,
82 unsigned int val, unsigned long flags, u8 width)
84 if (flags & CLK_DIVIDER_ONE_BASED)
86 if (flags & CLK_DIVIDER_POWER_OF_TWO)
88 if (flags & CLK_DIVIDER_MAX_AT_ZERO)
89 return val ? val : div_mask(width) + 1;
91 return _get_table_div(table, val);
95 static unsigned int _get_table_val(const struct clk_div_table *table,
98 const struct clk_div_table *clkt;
100 for (clkt = table; clkt->div; clkt++)
101 if (clkt->div == div)
106 static unsigned int _get_val(const struct clk_div_table *table,
107 unsigned int div, unsigned long flags, u8 width)
109 if (flags & CLK_DIVIDER_ONE_BASED)
111 if (flags & CLK_DIVIDER_POWER_OF_TWO)
113 if (flags & CLK_DIVIDER_MAX_AT_ZERO)
114 return (div == div_mask(width) + 1) ? 0 : div;
116 return _get_table_val(table, div);
120 unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
122 const struct clk_div_table *table,
125 struct clk_divider *divider = to_clk_divider(hw);
128 div = _get_div(table, val, flags, divider->width);
130 WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
131 "%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
132 clk_hw_get_name(hw));
136 return DIV_ROUND_UP_ULL((u64)parent_rate, div);
138 EXPORT_SYMBOL_GPL(divider_recalc_rate);
140 static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
141 unsigned long parent_rate)
143 struct clk_divider *divider = to_clk_divider(hw);
146 val = clk_readl(divider->reg) >> divider->shift;
147 val &= div_mask(divider->width);
149 return divider_recalc_rate(hw, parent_rate, val, divider->table,
153 static bool _is_valid_table_div(const struct clk_div_table *table,
156 const struct clk_div_table *clkt;
158 for (clkt = table; clkt->div; clkt++)
159 if (clkt->div == div)
164 static bool _is_valid_div(const struct clk_div_table *table, unsigned int div,
167 if (flags & CLK_DIVIDER_POWER_OF_TWO)
168 return is_power_of_2(div);
170 return _is_valid_table_div(table, div);
174 static int _round_up_table(const struct clk_div_table *table, int div)
176 const struct clk_div_table *clkt;
179 for (clkt = table; clkt->div; clkt++) {
180 if (clkt->div == div)
182 else if (clkt->div < div)
185 if ((clkt->div - div) < (up - div))
192 static int _round_down_table(const struct clk_div_table *table, int div)
194 const struct clk_div_table *clkt;
195 int down = _get_table_mindiv(table);
197 for (clkt = table; clkt->div; clkt++) {
198 if (clkt->div == div)
200 else if (clkt->div > div)
203 if ((div - clkt->div) < (div - down))
210 static int _div_round_up(const struct clk_div_table *table,
211 unsigned long parent_rate, unsigned long rate,
214 int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
216 if (flags & CLK_DIVIDER_POWER_OF_TWO)
217 div = __roundup_pow_of_two(div);
219 div = _round_up_table(table, div);
224 static int _div_round_closest(const struct clk_div_table *table,
225 unsigned long parent_rate, unsigned long rate,
229 unsigned long up_rate, down_rate;
231 up = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
232 down = parent_rate / rate;
234 if (flags & CLK_DIVIDER_POWER_OF_TWO) {
235 up = __roundup_pow_of_two(up);
236 down = __rounddown_pow_of_two(down);
238 up = _round_up_table(table, up);
239 down = _round_down_table(table, down);
242 up_rate = DIV_ROUND_UP_ULL((u64)parent_rate, up);
243 down_rate = DIV_ROUND_UP_ULL((u64)parent_rate, down);
245 return (rate - up_rate) <= (down_rate - rate) ? up : down;
248 static int _div_round(const struct clk_div_table *table,
249 unsigned long parent_rate, unsigned long rate,
252 if (flags & CLK_DIVIDER_ROUND_CLOSEST)
253 return _div_round_closest(table, parent_rate, rate, flags);
255 return _div_round_up(table, parent_rate, rate, flags);
258 static bool _is_best_div(unsigned long rate, unsigned long now,
259 unsigned long best, unsigned long flags)
261 if (flags & CLK_DIVIDER_ROUND_CLOSEST)
262 return abs(rate - now) < abs(rate - best);
264 return now <= rate && now > best;
267 static int _next_div(const struct clk_div_table *table, int div,
272 if (flags & CLK_DIVIDER_POWER_OF_TWO)
273 return __roundup_pow_of_two(div);
275 return _round_up_table(table, div);
280 static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
281 unsigned long *best_parent_rate,
282 const struct clk_div_table *table, u8 width,
286 unsigned long parent_rate, best = 0, now, maxdiv;
287 unsigned long parent_rate_saved = *best_parent_rate;
292 maxdiv = _get_maxdiv(table, width, flags);
294 if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
295 parent_rate = *best_parent_rate;
296 bestdiv = _div_round(table, parent_rate, rate, flags);
297 bestdiv = bestdiv == 0 ? 1 : bestdiv;
298 bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
303 * The maximum divider we can use without overflowing
304 * unsigned long in rate * i below
306 maxdiv = min(ULONG_MAX / rate, maxdiv);
308 for (i = 1; i <= maxdiv; i = _next_div(table, i, flags)) {
309 if (!_is_valid_div(table, i, flags))
311 if (rate * i == parent_rate_saved) {
313 * It's the most ideal case if the requested rate can be
314 * divided from parent clock without needing to change
315 * parent rate, so return the divider immediately.
317 *best_parent_rate = parent_rate_saved;
320 parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
322 now = DIV_ROUND_UP_ULL((u64)parent_rate, i);
323 if (_is_best_div(rate, now, best, flags)) {
326 *best_parent_rate = parent_rate;
331 bestdiv = _get_maxdiv(table, width, flags);
332 *best_parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), 1);
338 long divider_round_rate(struct clk_hw *hw, unsigned long rate,
339 unsigned long *prate, const struct clk_div_table *table,
340 u8 width, unsigned long flags)
344 div = clk_divider_bestdiv(hw, rate, prate, table, width, flags);
346 return DIV_ROUND_UP_ULL((u64)*prate, div);
348 EXPORT_SYMBOL_GPL(divider_round_rate);
350 static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
351 unsigned long *prate)
353 struct clk_divider *divider = to_clk_divider(hw);
356 /* if read only, just return current value */
357 if (divider->flags & CLK_DIVIDER_READ_ONLY) {
358 bestdiv = readl(divider->reg) >> divider->shift;
359 bestdiv &= div_mask(divider->width);
360 bestdiv = _get_div(divider->table, bestdiv, divider->flags,
362 return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
365 return divider_round_rate(hw, rate, prate, divider->table,
366 divider->width, divider->flags);
369 int divider_get_val(unsigned long rate, unsigned long parent_rate,
370 const struct clk_div_table *table, u8 width,
373 unsigned int div, value;
375 div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
377 if (!_is_valid_div(table, div, flags))
380 value = _get_val(table, div, flags, width);
382 return min_t(unsigned int, value, div_mask(width));
384 EXPORT_SYMBOL_GPL(divider_get_val);
386 static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
387 unsigned long parent_rate)
389 struct clk_divider *divider = to_clk_divider(hw);
391 unsigned long flags = 0;
394 value = divider_get_val(rate, parent_rate, divider->table,
395 divider->width, divider->flags);
398 spin_lock_irqsave(divider->lock, flags);
400 __acquire(divider->lock);
402 if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
403 val = div_mask(divider->width) << (divider->shift + 16);
405 val = clk_readl(divider->reg);
406 val &= ~(div_mask(divider->width) << divider->shift);
408 val |= value << divider->shift;
409 clk_writel(val, divider->reg);
412 spin_unlock_irqrestore(divider->lock, flags);
414 __release(divider->lock);
419 const struct clk_ops clk_divider_ops = {
420 .recalc_rate = clk_divider_recalc_rate,
421 .round_rate = clk_divider_round_rate,
422 .set_rate = clk_divider_set_rate,
424 EXPORT_SYMBOL_GPL(clk_divider_ops);
426 static struct clk *_register_divider(struct device *dev, const char *name,
427 const char *parent_name, unsigned long flags,
428 void __iomem *reg, u8 shift, u8 width,
429 u8 clk_divider_flags, const struct clk_div_table *table,
432 struct clk_divider *div;
434 struct clk_init_data init;
436 if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
437 if (width + shift > 16) {
438 pr_warn("divider value exceeds LOWORD field\n");
439 return ERR_PTR(-EINVAL);
443 /* allocate the divider */
444 div = kzalloc(sizeof(*div), GFP_KERNEL);
446 return ERR_PTR(-ENOMEM);
449 init.ops = &clk_divider_ops;
450 init.flags = flags | CLK_IS_BASIC;
451 init.parent_names = (parent_name ? &parent_name: NULL);
452 init.num_parents = (parent_name ? 1 : 0);
454 /* struct clk_divider assignments */
458 div->flags = clk_divider_flags;
460 div->hw.init = &init;
463 /* register the clock */
464 clk = clk_register(dev, &div->hw);
473 * clk_register_divider - register a divider clock with the clock framework
474 * @dev: device registering this clock
475 * @name: name of this clock
476 * @parent_name: name of clock's parent
477 * @flags: framework-specific flags
478 * @reg: register address to adjust divider
479 * @shift: number of bits to shift the bitfield
480 * @width: width of the bitfield
481 * @clk_divider_flags: divider-specific flags for this clock
482 * @lock: shared register lock for this clock
484 struct clk *clk_register_divider(struct device *dev, const char *name,
485 const char *parent_name, unsigned long flags,
486 void __iomem *reg, u8 shift, u8 width,
487 u8 clk_divider_flags, spinlock_t *lock)
489 return _register_divider(dev, name, parent_name, flags, reg, shift,
490 width, clk_divider_flags, NULL, lock);
492 EXPORT_SYMBOL_GPL(clk_register_divider);
495 * clk_register_divider_table - register a table based divider clock with
496 * the clock framework
497 * @dev: device registering this clock
498 * @name: name of this clock
499 * @parent_name: name of clock's parent
500 * @flags: framework-specific flags
501 * @reg: register address to adjust divider
502 * @shift: number of bits to shift the bitfield
503 * @width: width of the bitfield
504 * @clk_divider_flags: divider-specific flags for this clock
505 * @table: array of divider/value pairs ending with a div set to 0
506 * @lock: shared register lock for this clock
508 struct clk *clk_register_divider_table(struct device *dev, const char *name,
509 const char *parent_name, unsigned long flags,
510 void __iomem *reg, u8 shift, u8 width,
511 u8 clk_divider_flags, const struct clk_div_table *table,
514 return _register_divider(dev, name, parent_name, flags, reg, shift,
515 width, clk_divider_flags, table, lock);
517 EXPORT_SYMBOL_GPL(clk_register_divider_table);
519 void clk_unregister_divider(struct clk *clk)
521 struct clk_divider *div;
524 hw = __clk_get_hw(clk);
528 div = to_clk_divider(hw);
533 EXPORT_SYMBOL_GPL(clk_unregister_divider);