1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
4 * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
5 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
6 *
7 * Adjustable divider clock implementation
8 */
9
10#include <linux/clk-provider.h>
11#include <linux/device.h>
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/io.h>
15#include <linux/err.h>
16#include <linux/string.h>
17#include <linux/log2.h>
18
19/*
20 * DOC: basic adjustable divider clock that cannot gate
21 *
22 * Traits of this clock:
23 * prepare - clk_prepare only ensures that parents are prepared
24 * enable - clk_enable only ensures that parents are enabled
25 * rate - rate is adjustable. clk->rate = ceiling(parent->rate / divisor)
26 * parent - fixed parent. No clk_set_parent support
27 */
28
29static inline u32 clk_div_readl(struct clk_divider *divider)
30{
31 if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
32 return ioread32be(divider->reg);
33
34 return readl(addr: divider->reg);
35}
36
37static inline void clk_div_writel(struct clk_divider *divider, u32 val)
38{
39 if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
40 iowrite32be(val, divider->reg);
41 else
42 writel(val, addr: divider->reg);
43}
44
45static unsigned int _get_table_maxdiv(const struct clk_div_table *table,
46 u8 width)
47{
48 unsigned int maxdiv = 0, mask = clk_div_mask(width);
49 const struct clk_div_table *clkt;
50
51 for (clkt = table; clkt->div; clkt++)
52 if (clkt->div > maxdiv && clkt->val <= mask)
53 maxdiv = clkt->div;
54 return maxdiv;
55}
56
57static unsigned int _get_table_mindiv(const struct clk_div_table *table)
58{
59 unsigned int mindiv = UINT_MAX;
60 const struct clk_div_table *clkt;
61
62 for (clkt = table; clkt->div; clkt++)
63 if (clkt->div < mindiv)
64 mindiv = clkt->div;
65 return mindiv;
66}
67
68static unsigned int _get_maxdiv(const struct clk_div_table *table, u8 width,
69 unsigned long flags)
70{
71 if (flags & CLK_DIVIDER_ONE_BASED)
72 return clk_div_mask(width);
73 if (flags & CLK_DIVIDER_POWER_OF_TWO)
74 return 1 << clk_div_mask(width);
75 if (table)
76 return _get_table_maxdiv(table, width);
77 return clk_div_mask(width) + 1;
78}
79
80static unsigned int _get_table_div(const struct clk_div_table *table,
81 unsigned int val)
82{
83 const struct clk_div_table *clkt;
84
85 for (clkt = table; clkt->div; clkt++)
86 if (clkt->val == val)
87 return clkt->div;
88 return 0;
89}
90
91static unsigned int _get_div(const struct clk_div_table *table,
92 unsigned int val, unsigned long flags, u8 width)
93{
94 if (flags & CLK_DIVIDER_ONE_BASED)
95 return val;
96 if (flags & CLK_DIVIDER_POWER_OF_TWO)
97 return 1 << val;
98 if (flags & CLK_DIVIDER_MAX_AT_ZERO)
99 return val ? val : clk_div_mask(width) + 1;
100 if (table)
101 return _get_table_div(table, val);
102 return val + 1;
103}
104
105static unsigned int _get_table_val(const struct clk_div_table *table,
106 unsigned int div)
107{
108 const struct clk_div_table *clkt;
109
110 for (clkt = table; clkt->div; clkt++)
111 if (clkt->div == div)
112 return clkt->val;
113 return 0;
114}
115
116static unsigned int _get_val(const struct clk_div_table *table,
117 unsigned int div, unsigned long flags, u8 width)
118{
119 if (flags & CLK_DIVIDER_ONE_BASED)
120 return div;
121 if (flags & CLK_DIVIDER_POWER_OF_TWO)
122 return __ffs(div);
123 if (flags & CLK_DIVIDER_MAX_AT_ZERO)
124 return (div == clk_div_mask(width) + 1) ? 0 : div;
125 if (table)
126 return _get_table_val(table, div);
127 return div - 1;
128}
129
130unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
131 unsigned int val,
132 const struct clk_div_table *table,
133 unsigned long flags, unsigned long width)
134{
135 unsigned int div;
136
137 div = _get_div(table, val, flags, width);
138 if (!div) {
139 WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
140 "%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
141 clk_hw_get_name(hw));
142 return parent_rate;
143 }
144
145 return DIV_ROUND_UP_ULL((u64)parent_rate, div);
146}
147EXPORT_SYMBOL_GPL(divider_recalc_rate);
148
149static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
150 unsigned long parent_rate)
151{
152 struct clk_divider *divider = to_clk_divider(hw);
153 unsigned int val;
154
155 val = clk_div_readl(divider) >> divider->shift;
156 val &= clk_div_mask(divider->width);
157
158 return divider_recalc_rate(hw, parent_rate, val, divider->table,
159 divider->flags, divider->width);
160}
161
162static bool _is_valid_table_div(const struct clk_div_table *table,
163 unsigned int div)
164{
165 const struct clk_div_table *clkt;
166
167 for (clkt = table; clkt->div; clkt++)
168 if (clkt->div == div)
169 return true;
170 return false;
171}
172
173static bool _is_valid_div(const struct clk_div_table *table, unsigned int div,
174 unsigned long flags)
175{
176 if (flags & CLK_DIVIDER_POWER_OF_TWO)
177 return is_power_of_2(n: div);
178 if (table)
179 return _is_valid_table_div(table, div);
180 return true;
181}
182
183static int _round_up_table(const struct clk_div_table *table, int div)
184{
185 const struct clk_div_table *clkt;
186 int up = INT_MAX;
187
188 for (clkt = table; clkt->div; clkt++) {
189 if (clkt->div == div)
190 return clkt->div;
191 else if (clkt->div < div)
192 continue;
193
194 if ((clkt->div - div) < (up - div))
195 up = clkt->div;
196 }
197
198 return up;
199}
200
201static int _round_down_table(const struct clk_div_table *table, int div)
202{
203 const struct clk_div_table *clkt;
204 int down = _get_table_mindiv(table);
205
206 for (clkt = table; clkt->div; clkt++) {
207 if (clkt->div == div)
208 return clkt->div;
209 else if (clkt->div > div)
210 continue;
211
212 if ((div - clkt->div) < (div - down))
213 down = clkt->div;
214 }
215
216 return down;
217}
218
219static int _div_round_up(const struct clk_div_table *table,
220 unsigned long parent_rate, unsigned long rate,
221 unsigned long flags)
222{
223 int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
224
225 if (flags & CLK_DIVIDER_POWER_OF_TWO)
226 div = __roundup_pow_of_two(n: div);
227 if (table)
228 div = _round_up_table(table, div);
229
230 return div;
231}
232
233static int _div_round_closest(const struct clk_div_table *table,
234 unsigned long parent_rate, unsigned long rate,
235 unsigned long flags)
236{
237 int up, down;
238 unsigned long up_rate, down_rate;
239
240 up = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
241 down = parent_rate / rate;
242
243 if (flags & CLK_DIVIDER_POWER_OF_TWO) {
244 up = __roundup_pow_of_two(n: up);
245 down = __rounddown_pow_of_two(n: down);
246 } else if (table) {
247 up = _round_up_table(table, div: up);
248 down = _round_down_table(table, div: down);
249 }
250
251 up_rate = DIV_ROUND_UP_ULL((u64)parent_rate, up);
252 down_rate = DIV_ROUND_UP_ULL((u64)parent_rate, down);
253
254 return (rate - up_rate) <= (down_rate - rate) ? up : down;
255}
256
257static int _div_round(const struct clk_div_table *table,
258 unsigned long parent_rate, unsigned long rate,
259 unsigned long flags)
260{
261 if (flags & CLK_DIVIDER_ROUND_CLOSEST)
262 return _div_round_closest(table, parent_rate, rate, flags);
263
264 return _div_round_up(table, parent_rate, rate, flags);
265}
266
267static bool _is_best_div(unsigned long rate, unsigned long now,
268 unsigned long best, unsigned long flags)
269{
270 if (flags & CLK_DIVIDER_ROUND_CLOSEST)
271 return abs(rate - now) < abs(rate - best);
272
273 return now <= rate && now > best;
274}
275
276static int _next_div(const struct clk_div_table *table, int div,
277 unsigned long flags)
278{
279 div++;
280
281 if (flags & CLK_DIVIDER_POWER_OF_TWO)
282 return __roundup_pow_of_two(n: div);
283 if (table)
284 return _round_up_table(table, div);
285
286 return div;
287}
288
289static int clk_divider_bestdiv(struct clk_hw *hw, struct clk_hw *parent,
290 unsigned long rate,
291 unsigned long *best_parent_rate,
292 const struct clk_div_table *table, u8 width,
293 unsigned long flags)
294{
295 int i, bestdiv = 0;
296 unsigned long parent_rate, best = 0, now, maxdiv;
297 unsigned long parent_rate_saved = *best_parent_rate;
298
299 if (!rate)
300 rate = 1;
301
302 maxdiv = _get_maxdiv(table, width, flags);
303
304 if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
305 parent_rate = *best_parent_rate;
306 bestdiv = _div_round(table, parent_rate, rate, flags);
307 bestdiv = bestdiv == 0 ? 1 : bestdiv;
308 bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
309 return bestdiv;
310 }
311
312 /*
313 * The maximum divider we can use without overflowing
314 * unsigned long in rate * i below
315 */
316 maxdiv = min(ULONG_MAX / rate, maxdiv);
317
318 for (i = _next_div(table, div: 0, flags); i <= maxdiv;
319 i = _next_div(table, div: i, flags)) {
320 if (rate * i == parent_rate_saved) {
321 /*
322 * It's the most ideal case if the requested rate can be
323 * divided from parent clock without needing to change
324 * parent rate, so return the divider immediately.
325 */
326 *best_parent_rate = parent_rate_saved;
327 return i;
328 }
329 parent_rate = clk_hw_round_rate(hw: parent, rate: rate * i);
330 now = DIV_ROUND_UP_ULL((u64)parent_rate, i);
331 if (_is_best_div(rate, now, best, flags)) {
332 bestdiv = i;
333 best = now;
334 *best_parent_rate = parent_rate;
335 }
336 }
337
338 if (!bestdiv) {
339 bestdiv = _get_maxdiv(table, width, flags);
340 *best_parent_rate = clk_hw_round_rate(hw: parent, rate: 1);
341 }
342
343 return bestdiv;
344}
345
346int divider_determine_rate(struct clk_hw *hw, struct clk_rate_request *req,
347 const struct clk_div_table *table, u8 width,
348 unsigned long flags)
349{
350 int div;
351
352 div = clk_divider_bestdiv(hw, parent: req->best_parent_hw, rate: req->rate,
353 best_parent_rate: &req->best_parent_rate, table, width, flags);
354
355 req->rate = DIV_ROUND_UP_ULL((u64)req->best_parent_rate, div);
356
357 return 0;
358}
359EXPORT_SYMBOL_GPL(divider_determine_rate);
360
361int divider_ro_determine_rate(struct clk_hw *hw, struct clk_rate_request *req,
362 const struct clk_div_table *table, u8 width,
363 unsigned long flags, unsigned int val)
364{
365 int div;
366
367 div = _get_div(table, val, flags, width);
368
369 /* Even a read-only clock can propagate a rate change */
370 if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
371 if (!req->best_parent_hw)
372 return -EINVAL;
373
374 req->best_parent_rate = clk_hw_round_rate(hw: req->best_parent_hw,
375 rate: req->rate * div);
376 }
377
378 req->rate = DIV_ROUND_UP_ULL((u64)req->best_parent_rate, div);
379
380 return 0;
381}
382EXPORT_SYMBOL_GPL(divider_ro_determine_rate);
383
384long divider_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
385 unsigned long rate, unsigned long *prate,
386 const struct clk_div_table *table,
387 u8 width, unsigned long flags)
388{
389 struct clk_rate_request req;
390 int ret;
391
392 clk_hw_init_rate_request(hw, req: &req, rate);
393 req.best_parent_rate = *prate;
394 req.best_parent_hw = parent;
395
396 ret = divider_determine_rate(hw, &req, table, width, flags);
397 if (ret)
398 return ret;
399
400 *prate = req.best_parent_rate;
401
402 return req.rate;
403}
404EXPORT_SYMBOL_GPL(divider_round_rate_parent);
405
406long divider_ro_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
407 unsigned long rate, unsigned long *prate,
408 const struct clk_div_table *table, u8 width,
409 unsigned long flags, unsigned int val)
410{
411 struct clk_rate_request req;
412 int ret;
413
414 clk_hw_init_rate_request(hw, req: &req, rate);
415 req.best_parent_rate = *prate;
416 req.best_parent_hw = parent;
417
418 ret = divider_ro_determine_rate(hw, &req, table, width, flags, val);
419 if (ret)
420 return ret;
421
422 *prate = req.best_parent_rate;
423
424 return req.rate;
425}
426EXPORT_SYMBOL_GPL(divider_ro_round_rate_parent);
427
428static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
429 unsigned long *prate)
430{
431 struct clk_divider *divider = to_clk_divider(hw);
432
433 /* if read only, just return current value */
434 if (divider->flags & CLK_DIVIDER_READ_ONLY) {
435 u32 val;
436
437 val = clk_div_readl(divider) >> divider->shift;
438 val &= clk_div_mask(divider->width);
439
440 return divider_ro_round_rate(hw, rate, prate, table: divider->table,
441 width: divider->width, flags: divider->flags,
442 val);
443 }
444
445 return divider_round_rate(hw, rate, prate, table: divider->table,
446 width: divider->width, flags: divider->flags);
447}
448
449static int clk_divider_determine_rate(struct clk_hw *hw,
450 struct clk_rate_request *req)
451{
452 struct clk_divider *divider = to_clk_divider(hw);
453
454 /* if read only, just return current value */
455 if (divider->flags & CLK_DIVIDER_READ_ONLY) {
456 u32 val;
457
458 val = clk_div_readl(divider) >> divider->shift;
459 val &= clk_div_mask(divider->width);
460
461 return divider_ro_determine_rate(hw, req, divider->table,
462 divider->width,
463 divider->flags, val);
464 }
465
466 return divider_determine_rate(hw, req, divider->table, divider->width,
467 divider->flags);
468}
469
470int divider_get_val(unsigned long rate, unsigned long parent_rate,
471 const struct clk_div_table *table, u8 width,
472 unsigned long flags)
473{
474 unsigned int div, value;
475
476 div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
477
478 if (!_is_valid_div(table, div, flags))
479 return -EINVAL;
480
481 value = _get_val(table, div, flags, width);
482
483 return min_t(unsigned int, value, clk_div_mask(width));
484}
485EXPORT_SYMBOL_GPL(divider_get_val);
486
487static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
488 unsigned long parent_rate)
489{
490 struct clk_divider *divider = to_clk_divider(hw);
491 int value;
492 unsigned long flags = 0;
493 u32 val;
494
495 value = divider_get_val(rate, parent_rate, divider->table,
496 divider->width, divider->flags);
497 if (value < 0)
498 return value;
499
500 if (divider->lock)
501 spin_lock_irqsave(divider->lock, flags);
502 else
503 __acquire(divider->lock);
504
505 if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
506 val = clk_div_mask(divider->width) << (divider->shift + 16);
507 } else {
508 val = clk_div_readl(divider);
509 val &= ~(clk_div_mask(divider->width) << divider->shift);
510 }
511 val |= (u32)value << divider->shift;
512 clk_div_writel(divider, val);
513
514 if (divider->lock)
515 spin_unlock_irqrestore(lock: divider->lock, flags);
516 else
517 __release(divider->lock);
518
519 return 0;
520}
521
522const struct clk_ops clk_divider_ops = {
523 .recalc_rate = clk_divider_recalc_rate,
524 .round_rate = clk_divider_round_rate,
525 .determine_rate = clk_divider_determine_rate,
526 .set_rate = clk_divider_set_rate,
527};
528EXPORT_SYMBOL_GPL(clk_divider_ops);
529
530const struct clk_ops clk_divider_ro_ops = {
531 .recalc_rate = clk_divider_recalc_rate,
532 .round_rate = clk_divider_round_rate,
533 .determine_rate = clk_divider_determine_rate,
534};
535EXPORT_SYMBOL_GPL(clk_divider_ro_ops);
536
537struct clk_hw *__clk_hw_register_divider(struct device *dev,
538 struct device_node *np, const char *name,
539 const char *parent_name, const struct clk_hw *parent_hw,
540 const struct clk_parent_data *parent_data, unsigned long flags,
541 void __iomem *reg, u8 shift, u8 width, u8 clk_divider_flags,
542 const struct clk_div_table *table, spinlock_t *lock)
543{
544 struct clk_divider *div;
545 struct clk_hw *hw;
546 struct clk_init_data init = {};
547 int ret;
548
549 if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
550 if (width + shift > 16) {
551 pr_warn("divider value exceeds LOWORD field\n");
552 return ERR_PTR(error: -EINVAL);
553 }
554 }
555
556 /* allocate the divider */
557 div = kzalloc(size: sizeof(*div), GFP_KERNEL);
558 if (!div)
559 return ERR_PTR(error: -ENOMEM);
560
561 init.name = name;
562 if (clk_divider_flags & CLK_DIVIDER_READ_ONLY)
563 init.ops = &clk_divider_ro_ops;
564 else
565 init.ops = &clk_divider_ops;
566 init.flags = flags;
567 init.parent_names = parent_name ? &parent_name : NULL;
568 init.parent_hws = parent_hw ? &parent_hw : NULL;
569 init.parent_data = parent_data;
570 if (parent_name || parent_hw || parent_data)
571 init.num_parents = 1;
572 else
573 init.num_parents = 0;
574
575 /* struct clk_divider assignments */
576 div->reg = reg;
577 div->shift = shift;
578 div->width = width;
579 div->flags = clk_divider_flags;
580 div->lock = lock;
581 div->hw.init = &init;
582 div->table = table;
583
584 /* register the clock */
585 hw = &div->hw;
586 ret = clk_hw_register(dev, hw);
587 if (ret) {
588 kfree(objp: div);
589 hw = ERR_PTR(error: ret);
590 }
591
592 return hw;
593}
594EXPORT_SYMBOL_GPL(__clk_hw_register_divider);
595
596/**
597 * clk_register_divider_table - register a table based divider clock with
598 * the clock framework
599 * @dev: device registering this clock
600 * @name: name of this clock
601 * @parent_name: name of clock's parent
602 * @flags: framework-specific flags
603 * @reg: register address to adjust divider
604 * @shift: number of bits to shift the bitfield
605 * @width: width of the bitfield
606 * @clk_divider_flags: divider-specific flags for this clock
607 * @table: array of divider/value pairs ending with a div set to 0
608 * @lock: shared register lock for this clock
609 */
610struct clk *clk_register_divider_table(struct device *dev, const char *name,
611 const char *parent_name, unsigned long flags,
612 void __iomem *reg, u8 shift, u8 width,
613 u8 clk_divider_flags, const struct clk_div_table *table,
614 spinlock_t *lock)
615{
616 struct clk_hw *hw;
617
618 hw = __clk_hw_register_divider(dev, NULL, name, parent_name, NULL,
619 NULL, flags, reg, shift, width, clk_divider_flags,
620 table, lock);
621 if (IS_ERR(ptr: hw))
622 return ERR_CAST(ptr: hw);
623 return hw->clk;
624}
625EXPORT_SYMBOL_GPL(clk_register_divider_table);
626
627void clk_unregister_divider(struct clk *clk)
628{
629 struct clk_divider *div;
630 struct clk_hw *hw;
631
632 hw = __clk_get_hw(clk);
633 if (!hw)
634 return;
635
636 div = to_clk_divider(hw);
637
638 clk_unregister(clk);
639 kfree(objp: div);
640}
641EXPORT_SYMBOL_GPL(clk_unregister_divider);
642
643/**
644 * clk_hw_unregister_divider - unregister a clk divider
645 * @hw: hardware-specific clock data to unregister
646 */
647void clk_hw_unregister_divider(struct clk_hw *hw)
648{
649 struct clk_divider *div;
650
651 div = to_clk_divider(hw);
652
653 clk_hw_unregister(hw);
654 kfree(objp: div);
655}
656EXPORT_SYMBOL_GPL(clk_hw_unregister_divider);
657
658static void devm_clk_hw_release_divider(struct device *dev, void *res)
659{
660 clk_hw_unregister_divider(*(struct clk_hw **)res);
661}
662
663struct clk_hw *__devm_clk_hw_register_divider(struct device *dev,
664 struct device_node *np, const char *name,
665 const char *parent_name, const struct clk_hw *parent_hw,
666 const struct clk_parent_data *parent_data, unsigned long flags,
667 void __iomem *reg, u8 shift, u8 width, u8 clk_divider_flags,
668 const struct clk_div_table *table, spinlock_t *lock)
669{
670 struct clk_hw **ptr, *hw;
671
672 ptr = devres_alloc(devm_clk_hw_release_divider, sizeof(*ptr), GFP_KERNEL);
673 if (!ptr)
674 return ERR_PTR(error: -ENOMEM);
675
676 hw = __clk_hw_register_divider(dev, np, name, parent_name, parent_hw,
677 parent_data, flags, reg, shift, width,
678 clk_divider_flags, table, lock);
679
680 if (!IS_ERR(ptr: hw)) {
681 *ptr = hw;
682 devres_add(dev, res: ptr);
683 } else {
684 devres_free(res: ptr);
685 }
686
687 return hw;
688}
689EXPORT_SYMBOL_GPL(__devm_clk_hw_register_divider);
690

source code of linux/drivers/clk/clk-divider.c