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 = DIV_ROUND_UP(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(d) ((1 << ((d)->width)) - 1)
35 static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
37 unsigned int maxdiv = 0;
38 const struct clk_div_table *clkt;
40 for (clkt = table; clkt->div; clkt++)
41 if (clkt->div > maxdiv)
46 static unsigned int _get_table_mindiv(const struct clk_div_table *table)
48 unsigned int mindiv = UINT_MAX;
49 const struct clk_div_table *clkt;
51 for (clkt = table; clkt->div; clkt++)
52 if (clkt->div < mindiv)
57 static unsigned int _get_maxdiv(struct clk_divider *divider)
59 if (divider->flags & CLK_DIVIDER_ONE_BASED)
60 return div_mask(divider);
61 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
62 return 1 << div_mask(divider);
64 return _get_table_maxdiv(divider->table);
65 return div_mask(divider) + 1;
68 static unsigned int _get_table_div(const struct clk_div_table *table,
71 const struct clk_div_table *clkt;
73 for (clkt = table; clkt->div; clkt++)
79 static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
81 if (divider->flags & CLK_DIVIDER_ONE_BASED)
83 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
86 return _get_table_div(divider->table, val);
90 static unsigned int _get_table_val(const struct clk_div_table *table,
93 const struct clk_div_table *clkt;
95 for (clkt = table; clkt->div; clkt++)
101 static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
103 if (divider->flags & CLK_DIVIDER_ONE_BASED)
105 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
108 return _get_table_val(divider->table, div);
112 static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
113 unsigned long parent_rate)
115 struct clk_divider *divider = to_clk_divider(hw);
116 unsigned int div, val;
118 val = readl(divider->reg) >> divider->shift;
119 val &= div_mask(divider);
121 div = _get_div(divider, val);
123 WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
124 "%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
125 __clk_get_name(hw->clk));
129 return DIV_ROUND_UP(parent_rate, div);
133 * The reverse of DIV_ROUND_UP: The maximum number which
136 #define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
138 static bool _is_valid_table_div(const struct clk_div_table *table,
141 const struct clk_div_table *clkt;
143 for (clkt = table; clkt->div; clkt++)
144 if (clkt->div == div)
149 static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
151 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
152 return is_power_of_2(div);
154 return _is_valid_table_div(divider->table, div);
158 static int _round_up_table(const struct clk_div_table *table, int div)
160 const struct clk_div_table *clkt;
163 for (clkt = table; clkt->div; clkt++) {
164 if (clkt->div == div)
166 else if (clkt->div < div)
169 if ((clkt->div - div) < (up - div))
176 static int _round_down_table(const struct clk_div_table *table, int div)
178 const struct clk_div_table *clkt;
179 int down = _get_table_mindiv(table);
181 for (clkt = table; clkt->div; clkt++) {
182 if (clkt->div == div)
184 else if (clkt->div > div)
187 if ((div - clkt->div) < (div - down))
194 static int _div_round_up(struct clk_divider *divider,
195 unsigned long parent_rate, unsigned long rate)
197 int div = DIV_ROUND_UP(parent_rate, rate);
199 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
200 div = __roundup_pow_of_two(div);
202 div = _round_up_table(divider->table, div);
207 static int _div_round_closest(struct clk_divider *divider,
208 unsigned long parent_rate, unsigned long rate)
212 up = down = div = DIV_ROUND_CLOSEST(parent_rate, rate);
214 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) {
215 up = __roundup_pow_of_two(div);
216 down = __rounddown_pow_of_two(div);
217 } else if (divider->table) {
218 up = _round_up_table(divider->table, div);
219 down = _round_down_table(divider->table, div);
222 return (up - div) <= (div - down) ? up : down;
225 static int _div_round(struct clk_divider *divider, unsigned long parent_rate,
228 if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
229 return _div_round_closest(divider, parent_rate, rate);
231 return _div_round_up(divider, parent_rate, rate);
234 static bool _is_best_div(struct clk_divider *divider,
235 unsigned long rate, unsigned long now, unsigned long best)
237 if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
238 return abs(rate - now) < abs(rate - best);
240 return now <= rate && now > best;
243 static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
244 unsigned long *best_parent_rate)
246 struct clk_divider *divider = to_clk_divider(hw);
248 unsigned long parent_rate, best = 0, now, maxdiv;
253 maxdiv = _get_maxdiv(divider);
255 if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
256 parent_rate = *best_parent_rate;
257 bestdiv = _div_round(divider, parent_rate, rate);
258 bestdiv = bestdiv == 0 ? 1 : bestdiv;
259 bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
264 * The maximum divider we can use without overflowing
265 * unsigned long in rate * i below
267 maxdiv = min(ULONG_MAX / rate, maxdiv);
269 for (i = 1; i <= maxdiv; i++) {
270 if (!_is_valid_div(divider, i))
272 parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
273 MULT_ROUND_UP(rate, i));
274 now = DIV_ROUND_UP(parent_rate, i);
275 if (_is_best_div(divider, rate, now, best)) {
278 *best_parent_rate = parent_rate;
283 bestdiv = _get_maxdiv(divider);
284 *best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
290 static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
291 unsigned long *prate)
294 div = clk_divider_bestdiv(hw, rate, prate);
296 return DIV_ROUND_UP(*prate, div);
299 static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
300 unsigned long parent_rate)
302 struct clk_divider *divider = to_clk_divider(hw);
303 unsigned int div, value;
304 unsigned long flags = 0;
307 div = DIV_ROUND_UP(parent_rate, rate);
309 if (!_is_valid_div(divider, div))
312 value = _get_val(divider, div);
314 if (value > div_mask(divider))
315 value = div_mask(divider);
318 spin_lock_irqsave(divider->lock, flags);
320 val = readl(divider->reg);
321 val &= ~(div_mask(divider) << divider->shift);
322 val |= value << divider->shift;
323 writel(val, divider->reg);
326 spin_unlock_irqrestore(divider->lock, flags);
331 const struct clk_ops clk_divider_ops = {
332 .recalc_rate = clk_divider_recalc_rate,
333 .round_rate = clk_divider_round_rate,
334 .set_rate = clk_divider_set_rate,
336 EXPORT_SYMBOL_GPL(clk_divider_ops);
338 static struct clk *_register_divider(struct device *dev, const char *name,
339 const char *parent_name, unsigned long flags,
340 void __iomem *reg, u8 shift, u8 width,
341 u8 clk_divider_flags, const struct clk_div_table *table,
344 struct clk_divider *div;
346 struct clk_init_data init;
348 /* allocate the divider */
349 div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
351 pr_err("%s: could not allocate divider clk\n", __func__);
352 return ERR_PTR(-ENOMEM);
356 init.ops = &clk_divider_ops;
357 init.flags = flags | CLK_IS_BASIC;
358 init.parent_names = (parent_name ? &parent_name: NULL);
359 init.num_parents = (parent_name ? 1 : 0);
361 /* struct clk_divider assignments */
365 div->flags = clk_divider_flags;
367 div->hw.init = &init;
370 /* register the clock */
371 clk = clk_register(dev, &div->hw);
380 * clk_register_divider - register a divider clock with the clock framework
381 * @dev: device registering this clock
382 * @name: name of this clock
383 * @parent_name: name of clock's parent
384 * @flags: framework-specific flags
385 * @reg: register address to adjust divider
386 * @shift: number of bits to shift the bitfield
387 * @width: width of the bitfield
388 * @clk_divider_flags: divider-specific flags for this clock
389 * @lock: shared register lock for this clock
391 struct clk *clk_register_divider(struct device *dev, const char *name,
392 const char *parent_name, unsigned long flags,
393 void __iomem *reg, u8 shift, u8 width,
394 u8 clk_divider_flags, spinlock_t *lock)
396 return _register_divider(dev, name, parent_name, flags, reg, shift,
397 width, clk_divider_flags, NULL, lock);
401 * clk_register_divider_table - register a table based divider clock with
402 * the clock framework
403 * @dev: device registering this clock
404 * @name: name of this clock
405 * @parent_name: name of clock's parent
406 * @flags: framework-specific flags
407 * @reg: register address to adjust divider
408 * @shift: number of bits to shift the bitfield
409 * @width: width of the bitfield
410 * @clk_divider_flags: divider-specific flags for this clock
411 * @table: array of divider/value pairs ending with a div set to 0
412 * @lock: shared register lock for this clock
414 struct clk *clk_register_divider_table(struct device *dev, const char *name,
415 const char *parent_name, unsigned long flags,
416 void __iomem *reg, u8 shift, u8 width,
417 u8 clk_divider_flags, const struct clk_div_table *table,
420 return _register_divider(dev, name, parent_name, flags, reg, shift,
421 width, clk_divider_flags, table, lock);