1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * PWM device driver for ST SoCs
5 * Copyright (C) 2013-2016 STMicroelectronics (R&D) Limited
7 * Author: Ajit Pal Singh <ajitpal.singh@st.com>
8 * Lee Jones <lee.jones@linaro.org>
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>
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>
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 */
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
38 #define STI_MAX_CPT_DEVS 4
39 #define CPT_DC_MAX 0xff
59 * Each capture input can be programmed to detect rising-edge, falling-edge,
60 * either edge or neither egde.
69 struct sti_cpt_ddata {
73 wait_queue_head_t wait;
76 struct 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 struct sti_cpt_ddata *ddata;
89 struct regmap *regmap;
90 struct sti_pwm_compat_data *cdata;
91 struct regmap_field *prescale_low;
92 struct regmap_field *prescale_high;
93 struct regmap_field *pwm_out_en;
94 struct regmap_field *pwm_cpt_en;
95 struct regmap_field *pwm_cpt_int_en;
96 struct regmap_field *pwm_cpt_int_stat;
98 struct pwm_device *cur;
99 unsigned long configured;
100 unsigned int en_count;
101 struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
105 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
106 [PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWM_CTRL, 0, 3),
107 [PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWM_CTRL, 11, 14),
108 [CPTCLK_PRESCALE] = REG_FIELD(STI_PWM_CTRL, 4, 8),
109 [PWM_OUT_EN] = REG_FIELD(STI_PWM_CTRL, 9, 9),
110 [PWM_CPT_EN] = REG_FIELD(STI_PWM_CTRL, 10, 10),
111 [PWM_CPT_INT_EN] = REG_FIELD(STI_INT_EN, 1, 4),
112 [PWM_CPT_INT_STAT] = REG_FIELD(STI_INT_STA, 1, 4),
115 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
117 return container_of(chip, struct sti_pwm_chip, chip);
121 * Calculate the prescaler value corresponding to the period.
123 static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
124 unsigned int *prescale)
126 struct sti_pwm_compat_data *cdata = pc->cdata;
127 unsigned long clk_rate;
131 clk_rate = clk_get_rate(pc->pwm_clk);
133 dev_err(pc->dev, "failed to get clock rate\n");
138 * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_cnt + 1)) - 1
140 value = NSEC_PER_SEC / clk_rate;
141 value *= cdata->max_pwm_cnt + 1;
146 ps = period / value - 1;
147 if (ps > cdata->max_prescale)
156 * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles. The
157 * only way to change the period (apart from changing the PWM input clock) is
158 * to change the PWM clock prescaler.
160 * The prescaler is of 8 bits, so 256 prescaler values and hence 256 possible
161 * period values are supported (for a particular clock rate). The requested
162 * period will be applied only if it matches one of these 256 values.
164 static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
165 int duty_ns, int period_ns)
167 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
168 struct sti_pwm_compat_data *cdata = pc->cdata;
169 unsigned int ncfg, value, prescale = 0;
170 struct pwm_device *cur = pc->cur;
171 struct device *dev = pc->dev;
172 bool period_same = false;
175 ncfg = hweight_long(pc->configured);
177 period_same = (period_ns == pwm_get_period(cur));
180 * Allow configuration changes if one of the following conditions
182 * 1. No devices have been configured.
183 * 2. Only one device has been configured and the new request is for
185 * 3. Only one device has been configured and the new request is for
186 * a new device and period of the new device is same as the current
188 * 4. More than one devices are configured and period of the new
189 * requestis the same as the current period.
192 ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
193 ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
194 ((ncfg > 1) && period_same)) {
195 /* Enable clock before writing to PWM registers. */
196 ret = clk_enable(pc->pwm_clk);
200 ret = clk_enable(pc->cpt_clk);
205 ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
209 value = prescale & PWM_PRESCALE_LOW_MASK;
211 ret = regmap_field_write(pc->prescale_low, value);
215 value = (prescale & PWM_PRESCALE_HIGH_MASK) >> 4;
217 ret = regmap_field_write(pc->prescale_high, value);
223 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
224 * When PWMVal == max_pwm_count,
225 * PWM pulse = (max_pwm_count + 1) local cycles,
226 * that is continuous pulse: signal never goes low.
228 value = cdata->max_pwm_cnt * duty_ns / period_ns;
230 ret = regmap_write(pc->regmap, PWM_OUT_VAL(pwm->hwpwm), value);
234 ret = regmap_field_write(pc->pwm_cpt_int_en, 0);
236 set_bit(pwm->hwpwm, &pc->configured);
239 dev_dbg(dev, "prescale:%u, period:%i, duty:%i, value:%u\n",
240 prescale, period_ns, duty_ns, value);
246 clk_disable(pc->pwm_clk);
247 clk_disable(pc->cpt_clk);
251 static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
253 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
254 struct device *dev = pc->dev;
258 * Since we have a common enable for all PWM devices, do not enable if
261 mutex_lock(&pc->sti_pwm_lock);
264 ret = clk_enable(pc->pwm_clk);
268 ret = clk_enable(pc->cpt_clk);
272 ret = regmap_field_write(pc->pwm_out_en, 1);
274 dev_err(dev, "failed to enable PWM device %u: %d\n",
283 mutex_unlock(&pc->sti_pwm_lock);
287 static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
289 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
291 mutex_lock(&pc->sti_pwm_lock);
293 if (--pc->en_count) {
294 mutex_unlock(&pc->sti_pwm_lock);
298 regmap_field_write(pc->pwm_out_en, 0);
300 clk_disable(pc->pwm_clk);
301 clk_disable(pc->cpt_clk);
303 mutex_unlock(&pc->sti_pwm_lock);
306 static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
308 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
310 clear_bit(pwm->hwpwm, &pc->configured);
313 static int sti_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm,
314 struct pwm_capture *result, unsigned long timeout)
316 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
317 struct sti_pwm_compat_data *cdata = pc->cdata;
318 struct sti_cpt_ddata *ddata = &cdata->ddata[pwm->hwpwm];
319 struct device *dev = pc->dev;
320 unsigned int effective_ticks;
321 unsigned long long high, low;
324 if (pwm->hwpwm >= cdata->cpt_num_devs) {
325 dev_err(dev, "device %u is not valid\n", pwm->hwpwm);
329 mutex_lock(&ddata->lock);
332 /* Prepare capture measurement */
333 regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_RISING);
334 regmap_field_write(pc->pwm_cpt_int_en, BIT(pwm->hwpwm));
337 ret = regmap_field_write(pc->pwm_cpt_en, 1);
339 dev_err(dev, "failed to enable PWM capture %u: %d\n",
344 ret = wait_event_interruptible_timeout(ddata->wait, ddata->index > 1,
345 msecs_to_jiffies(timeout));
347 regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_DISABLED);
349 if (ret == -ERESTARTSYS)
352 switch (ddata->index) {
356 * Getting here could mean:
357 * - input signal is constant of less than 1 Hz
358 * - there is no input signal at all
360 * In such case the frequency is rounded down to 0
363 result->duty_cycle = 0;
368 /* We have everying we need */
369 high = ddata->snapshot[1] - ddata->snapshot[0];
370 low = ddata->snapshot[2] - ddata->snapshot[1];
372 effective_ticks = clk_get_rate(pc->cpt_clk);
374 result->period = (high + low) * NSEC_PER_SEC;
375 result->period /= effective_ticks;
377 result->duty_cycle = high * NSEC_PER_SEC;
378 result->duty_cycle /= effective_ticks;
383 dev_err(dev, "internal error\n");
388 /* Disable capture */
389 regmap_field_write(pc->pwm_cpt_en, 0);
391 mutex_unlock(&ddata->lock);
395 static const struct pwm_ops sti_pwm_ops = {
396 .capture = sti_pwm_capture,
397 .config = sti_pwm_config,
398 .enable = sti_pwm_enable,
399 .disable = sti_pwm_disable,
400 .free = sti_pwm_free,
401 .owner = THIS_MODULE,
404 static irqreturn_t sti_pwm_interrupt(int irq, void *data)
406 struct sti_pwm_chip *pc = data;
407 struct device *dev = pc->dev;
408 struct sti_cpt_ddata *ddata;
410 unsigned int cpt_int_stat;
414 ret = regmap_field_read(pc->pwm_cpt_int_stat, &cpt_int_stat);
418 while (cpt_int_stat) {
419 devicenum = ffs(cpt_int_stat) - 1;
421 ddata = &pc->cdata->ddata[devicenum];
427 * __| |_________________| |________
430 * Capture start by the first available rising edge. When a
431 * capture event occurs, capture value (CPT_VALx) is stored,
432 * index incremented, capture edge changed.
434 * After the capture, if the index > 1, we have collected the
435 * necessary data so we signal the thread waiting for it and
436 * disable the capture by setting capture edge to none
439 regmap_read(pc->regmap,
440 PWM_CPT_VAL(devicenum),
441 &ddata->snapshot[ddata->index]);
443 switch (ddata->index) {
446 regmap_read(pc->regmap, PWM_CPT_EDGE(devicenum), ®);
447 reg ^= PWM_CPT_EDGE_MASK;
448 regmap_write(pc->regmap, PWM_CPT_EDGE(devicenum), reg);
454 regmap_write(pc->regmap,
455 PWM_CPT_EDGE(devicenum),
457 wake_up(&ddata->wait);
461 dev_err(dev, "Internal error\n");
464 cpt_int_stat &= ~BIT_MASK(devicenum);
469 /* Just ACK everything */
470 regmap_write(pc->regmap, PWM_INT_ACK, PWM_INT_ACK_MASK);
475 static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
477 struct device *dev = pc->dev;
478 const struct reg_field *reg_fields;
479 struct device_node *np = dev->of_node;
480 struct sti_pwm_compat_data *cdata = pc->cdata;
484 ret = of_property_read_u32(np, "st,pwm-num-chan", &num_devs);
486 cdata->pwm_num_devs = num_devs;
488 ret = of_property_read_u32(np, "st,capture-num-chan", &num_devs);
490 cdata->cpt_num_devs = num_devs;
492 if (!cdata->pwm_num_devs && !cdata->cpt_num_devs) {
493 dev_err(dev, "No channels configured\n");
497 reg_fields = cdata->reg_fields;
499 pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
500 reg_fields[PWMCLK_PRESCALE_LOW]);
501 if (IS_ERR(pc->prescale_low))
502 return PTR_ERR(pc->prescale_low);
504 pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
505 reg_fields[PWMCLK_PRESCALE_HIGH]);
506 if (IS_ERR(pc->prescale_high))
507 return PTR_ERR(pc->prescale_high);
510 pc->pwm_out_en = devm_regmap_field_alloc(dev, pc->regmap,
511 reg_fields[PWM_OUT_EN]);
512 if (IS_ERR(pc->pwm_out_en))
513 return PTR_ERR(pc->pwm_out_en);
515 pc->pwm_cpt_en = devm_regmap_field_alloc(dev, pc->regmap,
516 reg_fields[PWM_CPT_EN]);
517 if (IS_ERR(pc->pwm_cpt_en))
518 return PTR_ERR(pc->pwm_cpt_en);
520 pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
521 reg_fields[PWM_CPT_INT_EN]);
522 if (IS_ERR(pc->pwm_cpt_int_en))
523 return PTR_ERR(pc->pwm_cpt_int_en);
525 pc->pwm_cpt_int_stat = devm_regmap_field_alloc(dev, pc->regmap,
526 reg_fields[PWM_CPT_INT_STAT]);
527 if (PTR_ERR_OR_ZERO(pc->pwm_cpt_int_stat))
528 return PTR_ERR(pc->pwm_cpt_int_stat);
533 static const struct regmap_config sti_pwm_regmap_config = {
539 static int sti_pwm_probe(struct platform_device *pdev)
541 struct device *dev = &pdev->dev;
542 struct sti_pwm_compat_data *cdata;
543 struct sti_pwm_chip *pc;
544 struct resource *res;
548 pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
552 cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
556 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
558 pc->mmio = devm_ioremap_resource(dev, res);
559 if (IS_ERR(pc->mmio))
560 return PTR_ERR(pc->mmio);
562 pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
563 &sti_pwm_regmap_config);
564 if (IS_ERR(pc->regmap))
565 return PTR_ERR(pc->regmap);
567 irq = platform_get_irq(pdev, 0);
571 ret = devm_request_irq(&pdev->dev, irq, sti_pwm_interrupt, 0,
574 dev_err(&pdev->dev, "Failed to request IRQ\n");
579 * Setup PWM data with default values: some values could be replaced
580 * with specific ones provided from Device Tree.
582 cdata->reg_fields = sti_pwm_regfields;
583 cdata->max_prescale = 0xff;
584 cdata->max_pwm_cnt = 255;
585 cdata->pwm_num_devs = 0;
586 cdata->cpt_num_devs = 0;
591 mutex_init(&pc->sti_pwm_lock);
593 ret = sti_pwm_probe_dt(pc);
597 if (cdata->pwm_num_devs) {
598 pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
599 if (IS_ERR(pc->pwm_clk)) {
600 dev_err(dev, "failed to get PWM clock\n");
601 return PTR_ERR(pc->pwm_clk);
604 ret = clk_prepare(pc->pwm_clk);
606 dev_err(dev, "failed to prepare clock\n");
611 if (cdata->cpt_num_devs) {
612 pc->cpt_clk = of_clk_get_by_name(dev->of_node, "capture");
613 if (IS_ERR(pc->cpt_clk)) {
614 dev_err(dev, "failed to get PWM capture clock\n");
615 return PTR_ERR(pc->cpt_clk);
618 ret = clk_prepare(pc->cpt_clk);
620 dev_err(dev, "failed to prepare clock\n");
624 cdata->ddata = devm_kzalloc(dev, cdata->cpt_num_devs * sizeof(*cdata->ddata), GFP_KERNEL);
630 pc->chip.ops = &sti_pwm_ops;
632 pc->chip.npwm = pc->cdata->pwm_num_devs;
634 for (i = 0; i < cdata->cpt_num_devs; i++) {
635 struct sti_cpt_ddata *ddata = &cdata->ddata[i];
637 init_waitqueue_head(&ddata->wait);
638 mutex_init(&ddata->lock);
641 ret = pwmchip_add(&pc->chip);
643 clk_unprepare(pc->pwm_clk);
644 clk_unprepare(pc->cpt_clk);
648 platform_set_drvdata(pdev, pc);
653 static int sti_pwm_remove(struct platform_device *pdev)
655 struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
658 for (i = 0; i < pc->cdata->pwm_num_devs; i++)
659 pwm_disable(&pc->chip.pwms[i]);
661 clk_unprepare(pc->pwm_clk);
662 clk_unprepare(pc->cpt_clk);
664 return pwmchip_remove(&pc->chip);
667 static const struct of_device_id sti_pwm_of_match[] = {
668 { .compatible = "st,sti-pwm", },
671 MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
673 static struct platform_driver sti_pwm_driver = {
676 .of_match_table = sti_pwm_of_match,
678 .probe = sti_pwm_probe,
679 .remove = sti_pwm_remove,
681 module_platform_driver(sti_pwm_driver);
683 MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
684 MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
685 MODULE_LICENSE("GPL");