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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * PWM device driver for ST SoCs
4 *
5 * Copyright (C) 2013-2016 STMicroelectronics (R&D) Limited
6 *
7 * Author: Ajit Pal Singh <ajitpal.singh@st.com>
8 * Lee Jones <lee.jones@linaro.org>
9 */
10
11#include <linux/clk.h>
12#include <linux/interrupt.h>
13#include <linux/math64.h>
14#include <linux/mfd/syscon.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/platform_device.h>
18#include <linux/pwm.h>
19#include <linux/regmap.h>
20#include <linux/sched.h>
21#include <linux/slab.h>
22#include <linux/time.h>
23#include <linux/wait.h>
24
25#define PWM_OUT_VAL(x) (0x00 + (4 * (x))) /* Device's Duty Cycle register */
26#define PWM_CPT_VAL(x) (0x10 + (4 * (x))) /* Capture value */
27#define PWM_CPT_EDGE(x) (0x30 + (4 * (x))) /* Edge to capture on */
28
29#define STI_PWM_CTRL 0x50 /* Control/Config register */
30#define STI_INT_EN 0x54 /* Interrupt Enable/Disable register */
31#define STI_INT_STA 0x58 /* Interrupt Status register */
32#define PWM_INT_ACK 0x5c
33#define PWM_PRESCALE_LOW_MASK 0x0f
34#define PWM_PRESCALE_HIGH_MASK 0xf0
35#define PWM_CPT_EDGE_MASK 0x03
36#define PWM_INT_ACK_MASK 0x1ff
37
38#define STI_MAX_CPT_DEVS 4
39#define CPT_DC_MAX 0xff
40
41/* Regfield IDs */
42enum {
43 /* Bits in PWM_CTRL*/
44 PWMCLK_PRESCALE_LOW,
45 PWMCLK_PRESCALE_HIGH,
46 CPTCLK_PRESCALE,
47
48 PWM_OUT_EN,
49 PWM_CPT_EN,
50
51 PWM_CPT_INT_EN,
52 PWM_CPT_INT_STAT,
53
54 /* Keep last */
55 MAX_REGFIELDS
56};
57
58/*
59 * Each capture input can be programmed to detect rising-edge, falling-edge,
60 * either edge or neither egde.
61 */
62enum sti_cpt_edge {
63 CPT_EDGE_DISABLED,
64 CPT_EDGE_RISING,
65 CPT_EDGE_FALLING,
66 CPT_EDGE_BOTH,
67};
68
69struct sti_cpt_ddata {
70 u32 snapshot[3];
71 unsigned int index;
72 struct mutex lock;
73 wait_queue_head_t wait;
74};
75
76struct sti_pwm_compat_data {
77 const struct reg_field *reg_fields;
78 unsigned int pwm_num_devs;
79 unsigned int cpt_num_devs;
80 unsigned int max_pwm_cnt;
81 unsigned int max_prescale;
82};
83
84struct sti_pwm_chip {
85 struct device *dev;
86 struct clk *pwm_clk;
87 struct clk *cpt_clk;
88 struct regmap *regmap;
89 struct sti_pwm_compat_data *cdata;
90 struct regmap_field *prescale_low;
91 struct regmap_field *prescale_high;
92 struct regmap_field *pwm_out_en;
93 struct regmap_field *pwm_cpt_en;
94 struct regmap_field *pwm_cpt_int_en;
95 struct regmap_field *pwm_cpt_int_stat;
96 struct pwm_chip chip;
97 struct pwm_device *cur;
98 unsigned long configured;
99 unsigned int en_count;
100 struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
101 void __iomem *mmio;
102};
103
104static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
105 [PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWM_CTRL, 0, 3),
106 [PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWM_CTRL, 11, 14),
107 [CPTCLK_PRESCALE] = REG_FIELD(STI_PWM_CTRL, 4, 8),
108 [PWM_OUT_EN] = REG_FIELD(STI_PWM_CTRL, 9, 9),
109 [PWM_CPT_EN] = REG_FIELD(STI_PWM_CTRL, 10, 10),
110 [PWM_CPT_INT_EN] = REG_FIELD(STI_INT_EN, 1, 4),
111 [PWM_CPT_INT_STAT] = REG_FIELD(STI_INT_STA, 1, 4),
112};
113
114static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
115{
116 return container_of(chip, struct sti_pwm_chip, chip);
117}
118
119/*
120 * Calculate the prescaler value corresponding to the period.
121 */
122static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
123 unsigned int *prescale)
124{
125 struct sti_pwm_compat_data *cdata = pc->cdata;
126 unsigned long clk_rate;
127 unsigned long value;
128 unsigned int ps;
129
130 clk_rate = clk_get_rate(pc->pwm_clk);
131 if (!clk_rate) {
132 dev_err(pc->dev, "failed to get clock rate\n");
133 return -EINVAL;
134 }
135
136 /*
137 * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_cnt + 1)) - 1
138 */
139 value = NSEC_PER_SEC / clk_rate;
140 value *= cdata->max_pwm_cnt + 1;
141
142 if (period % value)
143 return -EINVAL;
144
145 ps = period / value - 1;
146 if (ps > cdata->max_prescale)
147 return -EINVAL;
148
149 *prescale = ps;
150
151 return 0;
152}
153
154/*
155 * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles. The
156 * only way to change the period (apart from changing the PWM input clock) is
157 * to change the PWM clock prescaler.
158 *
159 * The prescaler is of 8 bits, so 256 prescaler values and hence 256 possible
160 * period values are supported (for a particular clock rate). The requested
161 * period will be applied only if it matches one of these 256 values.
162 */
163static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
164 int duty_ns, int period_ns)
165{
166 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
167 struct sti_pwm_compat_data *cdata = pc->cdata;
168 unsigned int ncfg, value, prescale = 0;
169 struct pwm_device *cur = pc->cur;
170 struct device *dev = pc->dev;
171 bool period_same = false;
172 int ret;
173
174 ncfg = hweight_long(pc->configured);
175 if (ncfg)
176 period_same = (period_ns == pwm_get_period(cur));
177
178 /*
179 * Allow configuration changes if one of the following conditions
180 * satisfy.
181 * 1. No devices have been configured.
182 * 2. Only one device has been configured and the new request is for
183 * the same device.
184 * 3. Only one device has been configured and the new request is for
185 * a new device and period of the new device is same as the current
186 * configured period.
187 * 4. More than one devices are configured and period of the new
188 * requestis the same as the current period.
189 */
190 if (!ncfg ||
191 ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
192 ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
193 ((ncfg > 1) && period_same)) {
194 /* Enable clock before writing to PWM registers. */
195 ret = clk_enable(pc->pwm_clk);
196 if (ret)
197 return ret;
198
199 ret = clk_enable(pc->cpt_clk);
200 if (ret)
201 return ret;
202
203 if (!period_same) {
204 ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
205 if (ret)
206 goto clk_dis;
207
208 value = prescale & PWM_PRESCALE_LOW_MASK;
209
210 ret = regmap_field_write(pc->prescale_low, value);
211 if (ret)
212 goto clk_dis;
213
214 value = (prescale & PWM_PRESCALE_HIGH_MASK) >> 4;
215
216 ret = regmap_field_write(pc->prescale_high, value);
217 if (ret)
218 goto clk_dis;
219 }
220
221 /*
222 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
223 * When PWMVal == max_pwm_count,
224 * PWM pulse = (max_pwm_count + 1) local cycles,
225 * that is continuous pulse: signal never goes low.
226 */
227 value = cdata->max_pwm_cnt * duty_ns / period_ns;
228
229 ret = regmap_write(pc->regmap, PWM_OUT_VAL(pwm->hwpwm), value);
230 if (ret)
231 goto clk_dis;
232
233 ret = regmap_field_write(pc->pwm_cpt_int_en, 0);
234
235 set_bit(pwm->hwpwm, &pc->configured);
236 pc->cur = pwm;
237
238 dev_dbg(dev, "prescale:%u, period:%i, duty:%i, value:%u\n",
239 prescale, period_ns, duty_ns, value);
240 } else {
241 return -EINVAL;
242 }
243
244clk_dis:
245 clk_disable(pc->pwm_clk);
246 clk_disable(pc->cpt_clk);
247 return ret;
248}
249
250static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
251{
252 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
253 struct device *dev = pc->dev;
254 int ret = 0;
255
256 /*
257 * Since we have a common enable for all PWM devices, do not enable if
258 * already enabled.
259 */
260 mutex_lock(&pc->sti_pwm_lock);
261
262 if (!pc->en_count) {
263 ret = clk_enable(pc->pwm_clk);
264 if (ret)
265 goto out;
266
267 ret = clk_enable(pc->cpt_clk);
268 if (ret)
269 goto out;
270
271 ret = regmap_field_write(pc->pwm_out_en, 1);
272 if (ret) {
273 dev_err(dev, "failed to enable PWM device %u: %d\n",
274 pwm->hwpwm, ret);
275 goto out;
276 }
277 }
278
279 pc->en_count++;
280
281out:
282 mutex_unlock(&pc->sti_pwm_lock);
283 return ret;
284}
285
286static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
287{
288 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
289
290 mutex_lock(&pc->sti_pwm_lock);
291
292 if (--pc->en_count) {
293 mutex_unlock(&pc->sti_pwm_lock);
294 return;
295 }
296
297 regmap_field_write(pc->pwm_out_en, 0);
298
299 clk_disable(pc->pwm_clk);
300 clk_disable(pc->cpt_clk);
301
302 mutex_unlock(&pc->sti_pwm_lock);
303}
304
305static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
306{
307 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
308
309 clear_bit(pwm->hwpwm, &pc->configured);
310}
311
312static int sti_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm,
313 struct pwm_capture *result, unsigned long timeout)
314{
315 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
316 struct sti_pwm_compat_data *cdata = pc->cdata;
317 struct sti_cpt_ddata *ddata = pwm_get_chip_data(pwm);
318 struct device *dev = pc->dev;
319 unsigned int effective_ticks;
320 unsigned long long high, low;
321 int ret;
322
323 if (pwm->hwpwm >= cdata->cpt_num_devs) {
324 dev_err(dev, "device %u is not valid\n", pwm->hwpwm);
325 return -EINVAL;
326 }
327
328 mutex_lock(&ddata->lock);
329 ddata->index = 0;
330
331 /* Prepare capture measurement */
332 regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_RISING);
333 regmap_field_write(pc->pwm_cpt_int_en, BIT(pwm->hwpwm));
334
335 /* Enable capture */
336 ret = regmap_field_write(pc->pwm_cpt_en, 1);
337 if (ret) {
338 dev_err(dev, "failed to enable PWM capture %u: %d\n",
339 pwm->hwpwm, ret);
340 goto out;
341 }
342
343 ret = wait_event_interruptible_timeout(ddata->wait, ddata->index > 1,
344 msecs_to_jiffies(timeout));
345
346 regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_DISABLED);
347
348 if (ret == -ERESTARTSYS)
349 goto out;
350
351 switch (ddata->index) {
352 case 0:
353 case 1:
354 /*
355 * Getting here could mean:
356 * - input signal is constant of less than 1 Hz
357 * - there is no input signal at all
358 *
359 * In such case the frequency is rounded down to 0
360 */
361 result->period = 0;
362 result->duty_cycle = 0;
363
364 break;
365
366 case 2:
367 /* We have everying we need */
368 high = ddata->snapshot[1] - ddata->snapshot[0];
369 low = ddata->snapshot[2] - ddata->snapshot[1];
370
371 effective_ticks = clk_get_rate(pc->cpt_clk);
372
373 result->period = (high + low) * NSEC_PER_SEC;
374 result->period /= effective_ticks;
375
376 result->duty_cycle = high * NSEC_PER_SEC;
377 result->duty_cycle /= effective_ticks;
378
379 break;
380
381 default:
382 dev_err(dev, "internal error\n");
383 break;
384 }
385
386out:
387 /* Disable capture */
388 regmap_field_write(pc->pwm_cpt_en, 0);
389
390 mutex_unlock(&ddata->lock);
391 return ret;
392}
393
394static int sti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
395 const struct pwm_state *state)
396{
397 int err;
398
399 if (state->polarity != PWM_POLARITY_NORMAL)
400 return -EINVAL;
401
402 if (!state->enabled) {
403 if (pwm->state.enabled)
404 sti_pwm_disable(chip, pwm);
405
406 return 0;
407 }
408
409 err = sti_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
410 if (err)
411 return err;
412
413 if (!pwm->state.enabled)
414 err = sti_pwm_enable(chip, pwm);
415
416 return err;
417}
418
419static const struct pwm_ops sti_pwm_ops = {
420 .capture = sti_pwm_capture,
421 .apply = sti_pwm_apply,
422 .free = sti_pwm_free,
423 .owner = THIS_MODULE,
424};
425
426static irqreturn_t sti_pwm_interrupt(int irq, void *data)
427{
428 struct sti_pwm_chip *pc = data;
429 struct device *dev = pc->dev;
430 struct sti_cpt_ddata *ddata;
431 int devicenum;
432 unsigned int cpt_int_stat;
433 unsigned int reg;
434 int ret = IRQ_NONE;
435
436 ret = regmap_field_read(pc->pwm_cpt_int_stat, &cpt_int_stat);
437 if (ret)
438 return ret;
439
440 while (cpt_int_stat) {
441 devicenum = ffs(cpt_int_stat) - 1;
442
443 ddata = pwm_get_chip_data(&pc->chip.pwms[devicenum]);
444
445 /*
446 * Capture input:
447 * _______ _______
448 * | | | |
449 * __| |_________________| |________
450 * ^0 ^1 ^2
451 *
452 * Capture start by the first available rising edge. When a
453 * capture event occurs, capture value (CPT_VALx) is stored,
454 * index incremented, capture edge changed.
455 *
456 * After the capture, if the index > 1, we have collected the
457 * necessary data so we signal the thread waiting for it and
458 * disable the capture by setting capture edge to none
459 */
460
461 regmap_read(pc->regmap,
462 PWM_CPT_VAL(devicenum),
463 &ddata->snapshot[ddata->index]);
464
465 switch (ddata->index) {
466 case 0:
467 case 1:
468 regmap_read(pc->regmap, PWM_CPT_EDGE(devicenum), ®);
469 reg ^= PWM_CPT_EDGE_MASK;
470 regmap_write(pc->regmap, PWM_CPT_EDGE(devicenum), reg);
471
472 ddata->index++;
473 break;
474
475 case 2:
476 regmap_write(pc->regmap,
477 PWM_CPT_EDGE(devicenum),
478 CPT_EDGE_DISABLED);
479 wake_up(&ddata->wait);
480 break;
481
482 default:
483 dev_err(dev, "Internal error\n");
484 }
485
486 cpt_int_stat &= ~BIT_MASK(devicenum);
487
488 ret = IRQ_HANDLED;
489 }
490
491 /* Just ACK everything */
492 regmap_write(pc->regmap, PWM_INT_ACK, PWM_INT_ACK_MASK);
493
494 return ret;
495}
496
497static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
498{
499 struct device *dev = pc->dev;
500 const struct reg_field *reg_fields;
501 struct device_node *np = dev->of_node;
502 struct sti_pwm_compat_data *cdata = pc->cdata;
503 u32 num_devs;
504 int ret;
505
506 ret = of_property_read_u32(np, "st,pwm-num-chan", &num_devs);
507 if (!ret)
508 cdata->pwm_num_devs = num_devs;
509
510 ret = of_property_read_u32(np, "st,capture-num-chan", &num_devs);
511 if (!ret)
512 cdata->cpt_num_devs = num_devs;
513
514 if (!cdata->pwm_num_devs && !cdata->cpt_num_devs) {
515 dev_err(dev, "No channels configured\n");
516 return -EINVAL;
517 }
518
519 reg_fields = cdata->reg_fields;
520
521 pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
522 reg_fields[PWMCLK_PRESCALE_LOW]);
523 if (IS_ERR(pc->prescale_low))
524 return PTR_ERR(pc->prescale_low);
525
526 pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
527 reg_fields[PWMCLK_PRESCALE_HIGH]);
528 if (IS_ERR(pc->prescale_high))
529 return PTR_ERR(pc->prescale_high);
530
531 pc->pwm_out_en = devm_regmap_field_alloc(dev, pc->regmap,
532 reg_fields[PWM_OUT_EN]);
533 if (IS_ERR(pc->pwm_out_en))
534 return PTR_ERR(pc->pwm_out_en);
535
536 pc->pwm_cpt_en = devm_regmap_field_alloc(dev, pc->regmap,
537 reg_fields[PWM_CPT_EN]);
538 if (IS_ERR(pc->pwm_cpt_en))
539 return PTR_ERR(pc->pwm_cpt_en);
540
541 pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
542 reg_fields[PWM_CPT_INT_EN]);
543 if (IS_ERR(pc->pwm_cpt_int_en))
544 return PTR_ERR(pc->pwm_cpt_int_en);
545
546 pc->pwm_cpt_int_stat = devm_regmap_field_alloc(dev, pc->regmap,
547 reg_fields[PWM_CPT_INT_STAT]);
548 if (PTR_ERR_OR_ZERO(pc->pwm_cpt_int_stat))
549 return PTR_ERR(pc->pwm_cpt_int_stat);
550
551 return 0;
552}
553
554static const struct regmap_config sti_pwm_regmap_config = {
555 .reg_bits = 32,
556 .val_bits = 32,
557 .reg_stride = 4,
558};
559
560static int sti_pwm_probe(struct platform_device *pdev)
561{
562 struct device *dev = &pdev->dev;
563 struct sti_pwm_compat_data *cdata;
564 struct sti_pwm_chip *pc;
565 unsigned int i;
566 int irq, ret;
567
568 pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
569 if (!pc)
570 return -ENOMEM;
571
572 cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
573 if (!cdata)
574 return -ENOMEM;
575
576 pc->mmio = devm_platform_ioremap_resource(pdev, 0);
577 if (IS_ERR(pc->mmio))
578 return PTR_ERR(pc->mmio);
579
580 pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
581 &sti_pwm_regmap_config);
582 if (IS_ERR(pc->regmap))
583 return PTR_ERR(pc->regmap);
584
585 irq = platform_get_irq(pdev, 0);
586 if (irq < 0)
587 return irq;
588
589 ret = devm_request_irq(&pdev->dev, irq, sti_pwm_interrupt, 0,
590 pdev->name, pc);
591 if (ret < 0) {
592 dev_err(&pdev->dev, "Failed to request IRQ\n");
593 return ret;
594 }
595
596 /*
597 * Setup PWM data with default values: some values could be replaced
598 * with specific ones provided from Device Tree.
599 */
600 cdata->reg_fields = sti_pwm_regfields;
601 cdata->max_prescale = 0xff;
602 cdata->max_pwm_cnt = 255;
603 cdata->pwm_num_devs = 0;
604 cdata->cpt_num_devs = 0;
605
606 pc->cdata = cdata;
607 pc->dev = dev;
608 pc->en_count = 0;
609 mutex_init(&pc->sti_pwm_lock);
610
611 ret = sti_pwm_probe_dt(pc);
612 if (ret)
613 return ret;
614
615 if (cdata->pwm_num_devs) {
616 pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
617 if (IS_ERR(pc->pwm_clk)) {
618 dev_err(dev, "failed to get PWM clock\n");
619 return PTR_ERR(pc->pwm_clk);
620 }
621
622 ret = clk_prepare(pc->pwm_clk);
623 if (ret) {
624 dev_err(dev, "failed to prepare clock\n");
625 return ret;
626 }
627 }
628
629 if (cdata->cpt_num_devs) {
630 pc->cpt_clk = of_clk_get_by_name(dev->of_node, "capture");
631 if (IS_ERR(pc->cpt_clk)) {
632 dev_err(dev, "failed to get PWM capture clock\n");
633 return PTR_ERR(pc->cpt_clk);
634 }
635
636 ret = clk_prepare(pc->cpt_clk);
637 if (ret) {
638 dev_err(dev, "failed to prepare clock\n");
639 return ret;
640 }
641 }
642
643 pc->chip.dev = dev;
644 pc->chip.ops = &sti_pwm_ops;
645 pc->chip.npwm = pc->cdata->pwm_num_devs;
646
647 ret = pwmchip_add(&pc->chip);
648 if (ret < 0) {
649 clk_unprepare(pc->pwm_clk);
650 clk_unprepare(pc->cpt_clk);
651 return ret;
652 }
653
654 for (i = 0; i < cdata->cpt_num_devs; i++) {
655 struct sti_cpt_ddata *ddata;
656
657 ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
658 if (!ddata)
659 return -ENOMEM;
660
661 init_waitqueue_head(&ddata->wait);
662 mutex_init(&ddata->lock);
663
664 pwm_set_chip_data(&pc->chip.pwms[i], ddata);
665 }
666
667 platform_set_drvdata(pdev, pc);
668
669 return 0;
670}
671
672static int sti_pwm_remove(struct platform_device *pdev)
673{
674 struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
675
676 pwmchip_remove(&pc->chip);
677
678 clk_unprepare(pc->pwm_clk);
679 clk_unprepare(pc->cpt_clk);
680
681 return 0;
682}
683
684static const struct of_device_id sti_pwm_of_match[] = {
685 { .compatible = "st,sti-pwm", },
686 { /* sentinel */ }
687};
688MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
689
690static struct platform_driver sti_pwm_driver = {
691 .driver = {
692 .name = "sti-pwm",
693 .of_match_table = sti_pwm_of_match,
694 },
695 .probe = sti_pwm_probe,
696 .remove = sti_pwm_remove,
697};
698module_platform_driver(sti_pwm_driver);
699
700MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
701MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
702MODULE_LICENSE("GPL");
1/*
2 * PWM device driver for ST SoCs.
3 * Author: Ajit Pal Singh <ajitpal.singh@st.com>
4 *
5 * Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 */
12
13#include <linux/clk.h>
14#include <linux/math64.h>
15#include <linux/mfd/syscon.h>
16#include <linux/module.h>
17#include <linux/of.h>
18#include <linux/platform_device.h>
19#include <linux/pwm.h>
20#include <linux/regmap.h>
21#include <linux/slab.h>
22#include <linux/time.h>
23
24#define STI_DS_REG(ch) (4 * (ch)) /* Channel's Duty Cycle register */
25#define STI_PWMCR 0x50 /* Control/Config register */
26#define STI_INTEN 0x54 /* Interrupt Enable/Disable register */
27#define PWM_PRESCALE_LOW_MASK 0x0f
28#define PWM_PRESCALE_HIGH_MASK 0xf0
29
30/* Regfield IDs */
31enum {
32 PWMCLK_PRESCALE_LOW,
33 PWMCLK_PRESCALE_HIGH,
34 PWM_EN,
35 PWM_INT_EN,
36
37 /* Keep last */
38 MAX_REGFIELDS
39};
40
41struct sti_pwm_compat_data {
42 const struct reg_field *reg_fields;
43 unsigned int num_chan;
44 unsigned int max_pwm_cnt;
45 unsigned int max_prescale;
46};
47
48struct sti_pwm_chip {
49 struct device *dev;
50 struct clk *clk;
51 unsigned long clk_rate;
52 struct regmap *regmap;
53 struct sti_pwm_compat_data *cdata;
54 struct regmap_field *prescale_low;
55 struct regmap_field *prescale_high;
56 struct regmap_field *pwm_en;
57 struct regmap_field *pwm_int_en;
58 struct pwm_chip chip;
59 struct pwm_device *cur;
60 unsigned long configured;
61 unsigned int en_count;
62 struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
63 void __iomem *mmio;
64};
65
66static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
67 [PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWMCR, 0, 3),
68 [PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWMCR, 11, 14),
69 [PWM_EN] = REG_FIELD(STI_PWMCR, 9, 9),
70 [PWM_INT_EN] = REG_FIELD(STI_INTEN, 0, 0),
71};
72
73static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
74{
75 return container_of(chip, struct sti_pwm_chip, chip);
76}
77
78/*
79 * Calculate the prescaler value corresponding to the period.
80 */
81static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
82 unsigned int *prescale)
83{
84 struct sti_pwm_compat_data *cdata = pc->cdata;
85 unsigned long val;
86 unsigned int ps;
87
88 /*
89 * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
90 */
91 val = NSEC_PER_SEC / pc->clk_rate;
92 val *= cdata->max_pwm_cnt + 1;
93
94 if (period % val) {
95 return -EINVAL;
96 } else {
97 ps = period / val - 1;
98 if (ps > cdata->max_prescale)
99 return -EINVAL;
100 }
101 *prescale = ps;
102
103 return 0;
104}
105
106/*
107 * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
108 * The only way to change the period (apart from changing the PWM input clock)
109 * is to change the PWM clock prescaler.
110 * The prescaler is of 8 bits, so 256 prescaler values and hence
111 * 256 possible period values are supported (for a particular clock rate).
112 * The requested period will be applied only if it matches one of these
113 * 256 values.
114 */
115static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
116 int duty_ns, int period_ns)
117{
118 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
119 struct sti_pwm_compat_data *cdata = pc->cdata;
120 struct pwm_device *cur = pc->cur;
121 struct device *dev = pc->dev;
122 unsigned int prescale = 0, pwmvalx;
123 int ret;
124 unsigned int ncfg;
125 bool period_same = false;
126
127 ncfg = hweight_long(pc->configured);
128 if (ncfg)
129 period_same = (period_ns == pwm_get_period(cur));
130
131 /* Allow configuration changes if one of the
132 * following conditions satisfy.
133 * 1. No channels have been configured.
134 * 2. Only one channel has been configured and the new request
135 * is for the same channel.
136 * 3. Only one channel has been configured and the new request is
137 * for a new channel and period of the new channel is same as
138 * the current configured period.
139 * 4. More than one channels are configured and period of the new
140 * requestis the same as the current period.
141 */
142 if (!ncfg ||
143 ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
144 ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
145 ((ncfg > 1) && period_same)) {
146 /* Enable clock before writing to PWM registers. */
147 ret = clk_enable(pc->clk);
148 if (ret)
149 return ret;
150
151 if (!period_same) {
152 ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
153 if (ret)
154 goto clk_dis;
155
156 ret =
157 regmap_field_write(pc->prescale_low,
158 prescale & PWM_PRESCALE_LOW_MASK);
159 if (ret)
160 goto clk_dis;
161
162 ret =
163 regmap_field_write(pc->prescale_high,
164 (prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
165 if (ret)
166 goto clk_dis;
167 }
168
169 /*
170 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
171 * When PWMVal == max_pwm_count,
172 * PWM pulse = (max_pwm_count + 1) local cycles,
173 * that is continuous pulse: signal never goes low.
174 */
175 pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
176
177 ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
178 if (ret)
179 goto clk_dis;
180
181 ret = regmap_field_write(pc->pwm_int_en, 0);
182
183 set_bit(pwm->hwpwm, &pc->configured);
184 pc->cur = pwm;
185
186 dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
187 prescale, period_ns, duty_ns, pwmvalx);
188 } else {
189 return -EINVAL;
190 }
191
192clk_dis:
193 clk_disable(pc->clk);
194 return ret;
195}
196
197static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
198{
199 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
200 struct device *dev = pc->dev;
201 int ret = 0;
202
203 /*
204 * Since we have a common enable for all PWM channels,
205 * do not enable if already enabled.
206 */
207 mutex_lock(&pc->sti_pwm_lock);
208 if (!pc->en_count) {
209 ret = clk_enable(pc->clk);
210 if (ret)
211 goto out;
212
213 ret = regmap_field_write(pc->pwm_en, 1);
214 if (ret) {
215 dev_err(dev, "failed to enable PWM device:%d\n",
216 pwm->hwpwm);
217 goto out;
218 }
219 }
220 pc->en_count++;
221out:
222 mutex_unlock(&pc->sti_pwm_lock);
223 return ret;
224}
225
226static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
227{
228 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
229
230 mutex_lock(&pc->sti_pwm_lock);
231 if (--pc->en_count) {
232 mutex_unlock(&pc->sti_pwm_lock);
233 return;
234 }
235 regmap_field_write(pc->pwm_en, 0);
236
237 clk_disable(pc->clk);
238 mutex_unlock(&pc->sti_pwm_lock);
239}
240
241static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
242{
243 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
244
245 clear_bit(pwm->hwpwm, &pc->configured);
246}
247
248static const struct pwm_ops sti_pwm_ops = {
249 .config = sti_pwm_config,
250 .enable = sti_pwm_enable,
251 .disable = sti_pwm_disable,
252 .free = sti_pwm_free,
253 .owner = THIS_MODULE,
254};
255
256static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
257{
258 struct device *dev = pc->dev;
259 const struct reg_field *reg_fields;
260 struct device_node *np = dev->of_node;
261 struct sti_pwm_compat_data *cdata = pc->cdata;
262 u32 num_chan;
263
264 of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
265 if (num_chan)
266 cdata->num_chan = num_chan;
267
268 reg_fields = cdata->reg_fields;
269
270 pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
271 reg_fields[PWMCLK_PRESCALE_LOW]);
272 if (IS_ERR(pc->prescale_low))
273 return PTR_ERR(pc->prescale_low);
274
275 pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
276 reg_fields[PWMCLK_PRESCALE_HIGH]);
277 if (IS_ERR(pc->prescale_high))
278 return PTR_ERR(pc->prescale_high);
279
280 pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
281 reg_fields[PWM_EN]);
282 if (IS_ERR(pc->pwm_en))
283 return PTR_ERR(pc->pwm_en);
284
285 pc->pwm_int_en = devm_regmap_field_alloc(dev, pc->regmap,
286 reg_fields[PWM_INT_EN]);
287 if (IS_ERR(pc->pwm_int_en))
288 return PTR_ERR(pc->pwm_int_en);
289
290 return 0;
291}
292
293static const struct regmap_config sti_pwm_regmap_config = {
294 .reg_bits = 32,
295 .val_bits = 32,
296 .reg_stride = 4,
297};
298
299static int sti_pwm_probe(struct platform_device *pdev)
300{
301 struct device *dev = &pdev->dev;
302 struct sti_pwm_compat_data *cdata;
303 struct sti_pwm_chip *pc;
304 struct resource *res;
305 int ret;
306
307 pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
308 if (!pc)
309 return -ENOMEM;
310
311 cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
312 if (!cdata)
313 return -ENOMEM;
314
315 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
316
317 pc->mmio = devm_ioremap_resource(dev, res);
318 if (IS_ERR(pc->mmio))
319 return PTR_ERR(pc->mmio);
320
321 pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
322 &sti_pwm_regmap_config);
323 if (IS_ERR(pc->regmap))
324 return PTR_ERR(pc->regmap);
325
326 /*
327 * Setup PWM data with default values: some values could be replaced
328 * with specific ones provided from Device Tree.
329 */
330 cdata->reg_fields = &sti_pwm_regfields[0];
331 cdata->max_prescale = 0xff;
332 cdata->max_pwm_cnt = 255;
333 cdata->num_chan = 1;
334
335 pc->cdata = cdata;
336 pc->dev = dev;
337 pc->en_count = 0;
338 mutex_init(&pc->sti_pwm_lock);
339
340 ret = sti_pwm_probe_dt(pc);
341 if (ret)
342 return ret;
343
344 pc->clk = of_clk_get_by_name(dev->of_node, "pwm");
345 if (IS_ERR(pc->clk)) {
346 dev_err(dev, "failed to get PWM clock\n");
347 return PTR_ERR(pc->clk);
348 }
349
350 pc->clk_rate = clk_get_rate(pc->clk);
351 if (!pc->clk_rate) {
352 dev_err(dev, "failed to get clock rate\n");
353 return -EINVAL;
354 }
355
356 ret = clk_prepare(pc->clk);
357 if (ret) {
358 dev_err(dev, "failed to prepare clock\n");
359 return ret;
360 }
361
362 pc->chip.dev = dev;
363 pc->chip.ops = &sti_pwm_ops;
364 pc->chip.base = -1;
365 pc->chip.npwm = pc->cdata->num_chan;
366 pc->chip.can_sleep = true;
367
368 ret = pwmchip_add(&pc->chip);
369 if (ret < 0) {
370 clk_unprepare(pc->clk);
371 return ret;
372 }
373
374 platform_set_drvdata(pdev, pc);
375
376 return 0;
377}
378
379static int sti_pwm_remove(struct platform_device *pdev)
380{
381 struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
382 unsigned int i;
383
384 for (i = 0; i < pc->cdata->num_chan; i++)
385 pwm_disable(&pc->chip.pwms[i]);
386
387 clk_unprepare(pc->clk);
388
389 return pwmchip_remove(&pc->chip);
390}
391
392static const struct of_device_id sti_pwm_of_match[] = {
393 { .compatible = "st,sti-pwm", },
394 { /* sentinel */ }
395};
396MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
397
398static struct platform_driver sti_pwm_driver = {
399 .driver = {
400 .name = "sti-pwm",
401 .of_match_table = sti_pwm_of_match,
402 },
403 .probe = sti_pwm_probe,
404 .remove = sti_pwm_remove,
405};
406module_platform_driver(sti_pwm_driver);
407
408MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
409MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
410MODULE_LICENSE("GPL");