pwm-pca9685.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Driver for PCA9685 16-channel 12-bit PWM LED controller
  4 *
  5 * Copyright (C) 2013 Steffen Trumtrar <s.trumtrar@pengutronix.de>
  6 * Copyright (C) 2015 Clemens Gruber <clemens.gruber@pqgruber.com>
  7 *
  8 * based on the pwm-twl-led.c driver
  9 */
 10
 11#include <linux/gpio/driver.h>
 12#include <linux/i2c.h>
 13#include <linux/module.h>
 14#include <linux/mutex.h>
 15#include <linux/platform_device.h>
 16#include <linux/property.h>
 17#include <linux/pwm.h>
 18#include <linux/regmap.h>
 19#include <linux/slab.h>
 20#include <linux/delay.h>
 21#include <linux/pm_runtime.h>
 22#include <linux/bitmap.h>
 23
 24/*
 25 * Because the PCA9685 has only one prescaler per chip, only the first channel
 26 * that is enabled is allowed to change the prescale register.
 27 * PWM channels requested afterwards must use a period that results in the same
 28 * prescale setting as the one set by the first requested channel.
 29 */
 30
 31#define PCA9685_MODE1		0x00
 32#define PCA9685_MODE2		0x01
 33#define PCA9685_SUBADDR1	0x02
 34#define PCA9685_SUBADDR2	0x03
 35#define PCA9685_SUBADDR3	0x04
 36#define PCA9685_ALLCALLADDR	0x05
 37#define PCA9685_LEDX_ON_L	0x06
 38#define PCA9685_LEDX_ON_H	0x07
 39#define PCA9685_LEDX_OFF_L	0x08
 40#define PCA9685_LEDX_OFF_H	0x09
 41
 42#define PCA9685_ALL_LED_ON_L	0xFA
 43#define PCA9685_ALL_LED_ON_H	0xFB
 44#define PCA9685_ALL_LED_OFF_L	0xFC
 45#define PCA9685_ALL_LED_OFF_H	0xFD
 46#define PCA9685_PRESCALE	0xFE
 47
 48#define PCA9685_PRESCALE_MIN	0x03	/* => max. frequency of 1526 Hz */
 49#define PCA9685_PRESCALE_MAX	0xFF	/* => min. frequency of 24 Hz */
 50
 51#define PCA9685_COUNTER_RANGE	4096
 52#define PCA9685_OSC_CLOCK_HZ	25000000	/* Internal oscillator with 25 MHz */
 53
 54/*
 55 * The time value of one counter tick. Note that NSEC_PER_SEC is an integer
 56 * multiple of PCA9685_OSC_CLOCK_HZ, so there is no rounding involved and we're
 57 * not loosing precision due to the early division.
 58 */
 59#define PCA9685_QUANTUM_NS(_prescale)	((NSEC_PER_SEC / PCA9685_OSC_CLOCK_HZ) * (_prescale + 1))
 60
 61#define PCA9685_NUMREGS		0xFF
 62#define PCA9685_MAXCHAN		0x10
 63
 64#define LED_FULL		BIT(4)
 65#define MODE1_ALLCALL		BIT(0)
 66#define MODE1_SUB3		BIT(1)
 67#define MODE1_SUB2		BIT(2)
 68#define MODE1_SUB1		BIT(3)
 69#define MODE1_SLEEP		BIT(4)
 70#define MODE1_AI		BIT(5)
 71
 72#define MODE2_INVRT		BIT(4)
 73#define MODE2_OUTDRV		BIT(2)
 74
 75#define LED_N_ON_H(N)	(PCA9685_LEDX_ON_H + (4 * (N)))
 76#define LED_N_ON_L(N)	(PCA9685_LEDX_ON_L + (4 * (N)))
 77#define LED_N_OFF_H(N)	(PCA9685_LEDX_OFF_H + (4 * (N)))
 78#define LED_N_OFF_L(N)	(PCA9685_LEDX_OFF_L + (4 * (N)))
 79
 80#define REG_ON_H(C)	((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_ON_H : LED_N_ON_H((C)))
 81#define REG_ON_L(C)	((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_ON_L : LED_N_ON_L((C)))
 82#define REG_OFF_H(C)	((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_OFF_H : LED_N_OFF_H((C)))
 83#define REG_OFF_L(C)	((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_OFF_L : LED_N_OFF_L((C)))
 84
 85struct pca9685 {
 86	struct regmap *regmap;
 87	struct mutex lock;
 88	DECLARE_BITMAP(pwms_enabled, PCA9685_MAXCHAN + 1);
 89};
 90
 91static inline struct pca9685 *to_pca(struct pwm_chip *chip)
 92{
 93	return pwmchip_get_drvdata(chip);
 94}
 95
 96/* This function is supposed to be called with the lock mutex held */
 97static bool pca9685_prescaler_can_change(struct pca9685 *pca, int channel)
 98{
 99	/* No PWM enabled: Change allowed */
100	if (bitmap_empty(pca->pwms_enabled, PCA9685_MAXCHAN + 1))
101		return true;
102	/* More than one PWM enabled: Change not allowed */
103	if (bitmap_weight(pca->pwms_enabled, PCA9685_MAXCHAN + 1) > 1)
104		return false;
105	/*
106	 * Only one PWM enabled: Change allowed if the PWM about to
107	 * be changed is the one that is already enabled
108	 */
109	return test_bit(channel, pca->pwms_enabled);
110}
111
112static int pca9685_read_reg(struct pwm_chip *chip, unsigned int reg, unsigned int *val)
113{
114	struct pca9685 *pca = to_pca(chip);
115	struct device *dev = pwmchip_parent(chip);
116	int err;
117
118	err = regmap_read(pca->regmap, reg, val);
119	if (err)
120		dev_err(dev, "regmap_read of register 0x%x failed: %pe\n", reg, ERR_PTR(err));
121
122	return err;
123}
124
125static int pca9685_write_reg(struct pwm_chip *chip, unsigned int reg, unsigned int val)
126{
127	struct pca9685 *pca = to_pca(chip);
128	struct device *dev = pwmchip_parent(chip);
129	int err;
130
131	err = regmap_write(pca->regmap, reg, val);
132	if (err)
133		dev_err(dev, "regmap_write to register 0x%x failed: %pe\n", reg, ERR_PTR(err));
134
135	return err;
136}
137
138static int pca9685_write_4reg(struct pwm_chip *chip, unsigned int reg, u8 val[4])
139{
140	struct pca9685 *pca = to_pca(chip);
141	struct device *dev = pwmchip_parent(chip);
142	int err;
143
144	err = regmap_bulk_write(pca->regmap, reg, val, 4);
145	if (err)
146		dev_err(dev, "regmap_write to register 0x%x failed: %pe\n", reg, ERR_PTR(err));
147
148	return err;
149}
150
151static int pca9685_set_sleep_mode(struct pwm_chip *chip, bool enable)
152{
153	struct pca9685 *pca = to_pca(chip);
154	int err;
155
156	err = regmap_update_bits(pca->regmap, PCA9685_MODE1,
157				 MODE1_SLEEP, enable ? MODE1_SLEEP : 0);
158	if (err)
159		return err;
160
161	if (!enable) {
162		/* Wait 500us for the oscillator to be back up */
163		udelay(500);
164	}
165
166	return 0;
167}
168
169struct pca9685_waveform {
170	u8 onoff[4];
171	u8 prescale;
172};
173
174static int pca9685_round_waveform_tohw(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_waveform *wf, void *_wfhw)
175{
176	struct pca9685_waveform *wfhw = _wfhw;
177	struct pca9685 *pca = to_pca(chip);
178	unsigned int best_prescale;
179	u8 prescale;
180	unsigned int period_ns, duty;
181	int ret_tohw = 0;
182
183	if (!wf->period_length_ns) {
184		*wfhw = (typeof(*wfhw)){
185			.onoff = { 0, 0, 0, LED_FULL, },
186			.prescale = 0,
187		};
188
189		dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] -> [%hhx %hhx %hhx %hhx] PSC:%hhx\n",
190			pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
191			wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale);
192
193		return 0;
194	}
195
196	if (wf->period_length_ns >= PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(255)) {
197		best_prescale = 255;
198	} else if (wf->period_length_ns < PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(3)) {
199		best_prescale = 3;
200		ret_tohw = 1;
201	} else {
202		best_prescale = (unsigned int)wf->period_length_ns / (PCA9685_COUNTER_RANGE * (NSEC_PER_SEC / PCA9685_OSC_CLOCK_HZ)) - 1;
203	}
204
205	guard(mutex)(&pca->lock);
206
207	if (!pca9685_prescaler_can_change(pca, pwm->hwpwm)) {
208		unsigned int current_prescale;
209		int ret;
210
211		ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &current_prescale);
212		if (ret)
213			return ret;
214
215		if (current_prescale > best_prescale)
216			ret_tohw = 1;
217
218		prescale = current_prescale;
219	} else {
220		prescale = best_prescale;
221	}
222
223	period_ns = PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);
224
225	duty = (unsigned)min_t(u64, wf->duty_length_ns, period_ns) / PCA9685_QUANTUM_NS(prescale);
226
227	if (duty < PCA9685_COUNTER_RANGE) {
228		unsigned int on, off;
229
230		on = (unsigned)min_t(u64, wf->duty_offset_ns, period_ns) / PCA9685_QUANTUM_NS(prescale);
231		off = (on + duty) % PCA9685_COUNTER_RANGE;
232
233		/*
234		 * With a zero duty cycle, it doesn't matter if period was
235		 * rounded up
236		 */
237		if (!duty)
238			ret_tohw = 0;
239
240		*wfhw = (typeof(*wfhw)){
241			.onoff = { on & 0xff, (on >> 8) & 0xf, off & 0xff, (off >> 8) & 0xf },
242			.prescale = prescale,
243		};
244	} else {
245		*wfhw = (typeof(*wfhw)){
246			.onoff = { 0, LED_FULL, 0, 0, },
247			.prescale = prescale,
248		};
249	}
250
251	dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] -> %s[%hhx %hhx %hhx %hhx] PSC:%hhx\n",
252		pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
253		ret_tohw ? "#" : "", wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale);
254
255	return ret_tohw;
256}
257
258static int pca9685_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,
259					 const void *_wfhw, struct pwm_waveform *wf)
260{
261	const struct pca9685_waveform *wfhw = _wfhw;
262	struct pca9685 *pca = to_pca(chip);
263	unsigned int prescale;
264
265	if (wfhw->prescale)
266		prescale = wfhw->prescale;
267	else
268		scoped_guard(mutex, &pca->lock) {
269			int ret;
270
271			ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &prescale);
272			if (ret)
273				return ret;
274		}
275
276	wf->period_length_ns = PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);
277
278	if (wfhw->onoff[3] & LED_FULL) {
279		wf->duty_length_ns = 0;
280		wf->duty_offset_ns = 0;
281	} else if (wfhw->onoff[1] & LED_FULL) {
282		wf->duty_length_ns = wf->period_length_ns;
283		wf->duty_offset_ns = 0;
284	} else {
285		unsigned int on = wfhw->onoff[0] | (wfhw->onoff[1] & 0xf) << 8;
286		unsigned int off = wfhw->onoff[2] | (wfhw->onoff[3] & 0xf) << 8;
287
288		wf->duty_length_ns = (off - on) % PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);
289		wf->duty_offset_ns = on * PCA9685_QUANTUM_NS(prescale);
290	}
291
292	dev_dbg(&chip->dev, "pwm#%u: [%hhx %hhx %hhx %hhx] PSC:%hhx -> %lld/%lld [+%lld]\n",
293		pwm->hwpwm,
294		wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale,
295		wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns);
296
297	return 0;
298}
299
300static int pca9685_read_waveform(struct pwm_chip *chip, struct pwm_device *pwm, void *_wfhw)
301{
302	struct pca9685_waveform *wfhw = _wfhw;
303	struct pca9685 *pca = to_pca(chip);
304	unsigned int prescale;
305	int ret;
306
307	guard(mutex)(&pca->lock);
308
309	ret = regmap_bulk_read(pca->regmap, REG_ON_L(pwm->hwpwm), &wfhw->onoff, 4);
310	if (ret)
311		return ret;
312
313	ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &prescale);
314	if (ret)
315		return ret;
316
317	wfhw->prescale = prescale;
318
319	return 0;
320}
321
322static int pca9685_write_waveform(struct pwm_chip *chip, struct pwm_device *pwm, const void *_wfhw)
323{
324	const struct pca9685_waveform *wfhw = _wfhw;
325	struct pca9685 *pca = to_pca(chip);
326	unsigned int current_prescale;
327	int ret;
328
329	guard(mutex)(&pca->lock);
330
331	if (wfhw->prescale) {
332		ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &current_prescale);
333		if (ret)
334			return ret;
335
336		if (current_prescale != wfhw->prescale) {
337			if (!pca9685_prescaler_can_change(pca, pwm->hwpwm))
338				return -EBUSY;
339
340			/* Put chip into sleep mode */
341			ret = pca9685_set_sleep_mode(chip, true);
342			if (ret)
343				return ret;
344
345			/* Change the chip-wide output frequency */
346			ret = regmap_write(pca->regmap, PCA9685_PRESCALE, wfhw->prescale);
347			if (ret)
348				return ret;
349
350			/* Wake the chip up */
351			ret = pca9685_set_sleep_mode(chip, false);
352			if (ret)
353				return ret;
354		}
355	}
356
357	return regmap_bulk_write(pca->regmap, REG_ON_L(pwm->hwpwm), &wfhw->onoff, 4);
358}
359
360static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
361{
362	struct pca9685 *pca = to_pca(chip);
363
364	if (pwm->hwpwm < PCA9685_MAXCHAN) {
365		/* PWMs - except the "all LEDs" channel - default to enabled */
366		mutex_lock(&pca->lock);
367		set_bit(pwm->hwpwm, pca->pwms_enabled);
368		mutex_unlock(&pca->lock);
369	}
370
371	pm_runtime_get_sync(pwmchip_parent(chip));
372
373	return 0;
374}
375
376static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
377{
378	struct pca9685 *pca = to_pca(chip);
379
380	mutex_lock(&pca->lock);
381	clear_bit(pwm->hwpwm, pca->pwms_enabled);
382	mutex_unlock(&pca->lock);
383
384	pm_runtime_put(pwmchip_parent(chip));
385}
386
387static const struct pwm_ops pca9685_pwm_ops = {
388	.sizeof_wfhw = sizeof(struct pca9685_waveform),
389	.round_waveform_tohw = pca9685_round_waveform_tohw,
390	.round_waveform_fromhw = pca9685_round_waveform_fromhw,
391	.read_waveform = pca9685_read_waveform,
392	.write_waveform = pca9685_write_waveform,
393	.request = pca9685_pwm_request,
394	.free = pca9685_pwm_free,
395};
396
397static bool pca9685_readable_reg(struct device *dev, unsigned int reg)
398{
399	/* The ALL_LED registers are readable but read as zero */
400	return reg <= REG_OFF_H(15) || reg >= PCA9685_PRESCALE;
401}
402
403static bool pca9685_writeable_reg(struct device *dev, unsigned int reg)
404{
405	return reg <= REG_OFF_H(15) || reg >= PCA9685_ALL_LED_ON_L;
406}
407
408static bool pca9685_volatile_reg(struct device *dev, unsigned int reg)
409{
410	/*
411	 * Writing to an ALL_LED register affects all LEDi registers, so they
412	 * are not cachable. :-\
413	 */
414	return reg < PCA9685_PRESCALE;
415}
416
417static const struct regmap_config pca9685_regmap_i2c_config = {
418	.reg_bits = 8,
419	.val_bits = 8,
420
421	.readable_reg = pca9685_readable_reg,
422	.writeable_reg = pca9685_writeable_reg,
423	.volatile_reg = pca9685_volatile_reg,
424
425	.max_register = PCA9685_NUMREGS,
426	.cache_type = REGCACHE_MAPLE,
427};
428
429static int pca9685_pwm_probe(struct i2c_client *client)
430{
431	struct pwm_chip *chip;
432	struct pca9685 *pca;
433	unsigned int reg;
434	int ret;
435
436	/* Add an extra channel for ALL_LED */
437	chip = devm_pwmchip_alloc(&client->dev, PCA9685_MAXCHAN + 1, sizeof(*pca));
438	if (IS_ERR(chip))
439		return PTR_ERR(chip);
440	pca = to_pca(chip);
441
442	pca->regmap = devm_regmap_init_i2c(client, &pca9685_regmap_i2c_config);
443	if (IS_ERR(pca->regmap)) {
444		ret = PTR_ERR(pca->regmap);
445		dev_err(&client->dev, "Failed to initialize register map: %d\n",
446			ret);
447		return ret;
448	}
449
450	i2c_set_clientdata(client, chip);
451
452	mutex_init(&pca->lock);
453
454	/* clear MODE2_OCH */
455	reg = 0;
456
457	if (device_property_read_bool(&client->dev, "invert"))
458		reg |= MODE2_INVRT;
459	else
460		reg &= ~MODE2_INVRT;
461
462	if (device_property_read_bool(&client->dev, "open-drain"))
463		reg &= ~MODE2_OUTDRV;
464	else
465		reg |= MODE2_OUTDRV;
466
467	ret = pca9685_write_reg(chip, PCA9685_MODE2, reg);
468	if (ret)
469		return ret;
470
471	/*
472	 * Disable all LED ALLCALL and SUBx addresses to avoid bus collisions,
473	 * enable Auto-Increment.
474	 */
475	pca9685_read_reg(chip, PCA9685_MODE1, &reg);
476	reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
477	reg |= MODE1_AI;
478	pca9685_write_reg(chip, PCA9685_MODE1, reg);
479
480	/* Reset OFF/ON registers to POR default */
481	ret = pca9685_write_4reg(chip, PCA9685_ALL_LED_ON_L, (u8[]){ 0, LED_FULL, 0, LED_FULL });
482	if (ret < 0)
483		return dev_err_probe(&client->dev, ret, "Failed to reset ON/OFF registers\n");
484
485	chip->ops = &pca9685_pwm_ops;
486
487	ret = pwmchip_add(chip);
488	if (ret < 0)
489		return ret;
490
491	pm_runtime_enable(&client->dev);
492
493	if (pm_runtime_enabled(&client->dev)) {
494		/*
495		 * Although the chip comes out of power-up in the sleep state,
496		 * we force it to sleep in case it was woken up before
497		 */
498		pca9685_set_sleep_mode(chip, true);
499		pm_runtime_set_suspended(&client->dev);
500	} else {
501		/* Wake the chip up if runtime PM is disabled */
502		pca9685_set_sleep_mode(chip, false);
503	}
504
505	return 0;
506}
507
508static void pca9685_pwm_remove(struct i2c_client *client)
509{
510	struct pwm_chip *chip = i2c_get_clientdata(client);
511
512	pwmchip_remove(chip);
513
514	if (!pm_runtime_enabled(&client->dev)) {
515		/* Put chip in sleep state if runtime PM is disabled */
516		pca9685_set_sleep_mode(chip, true);
517	}
518
519	pm_runtime_disable(&client->dev);
520}
521
522static int __maybe_unused pca9685_pwm_runtime_suspend(struct device *dev)
523{
524	struct i2c_client *client = to_i2c_client(dev);
525	struct pwm_chip *chip = i2c_get_clientdata(client);
526
527	pca9685_set_sleep_mode(chip, true);
528	return 0;
529}
530
531static int __maybe_unused pca9685_pwm_runtime_resume(struct device *dev)
532{
533	struct i2c_client *client = to_i2c_client(dev);
534	struct pwm_chip *chip = i2c_get_clientdata(client);
535
536	pca9685_set_sleep_mode(chip, false);
537	return 0;
538}
539
540static const struct i2c_device_id pca9685_id[] = {
541	{ "pca9685" },
542	{ /* sentinel */ }
543};
544MODULE_DEVICE_TABLE(i2c, pca9685_id);
545
546static const struct acpi_device_id pca9685_acpi_ids[] = {
547	{ "INT3492", 0 },
548	{ /* sentinel */ },
549};
550MODULE_DEVICE_TABLE(acpi, pca9685_acpi_ids);
551
552static const struct of_device_id pca9685_dt_ids[] = {
553	{ .compatible = "nxp,pca9685-pwm", },
554	{ /* sentinel */ }
555};
556MODULE_DEVICE_TABLE(of, pca9685_dt_ids);
557
558static const struct dev_pm_ops pca9685_pwm_pm = {
559	SET_RUNTIME_PM_OPS(pca9685_pwm_runtime_suspend,
560			   pca9685_pwm_runtime_resume, NULL)
561};
562
563static struct i2c_driver pca9685_i2c_driver = {
564	.driver = {
565		.name = "pca9685-pwm",
566		.acpi_match_table = pca9685_acpi_ids,
567		.of_match_table = pca9685_dt_ids,
568		.pm = &pca9685_pwm_pm,
569	},
570	.probe = pca9685_pwm_probe,
571	.remove = pca9685_pwm_remove,
572	.id_table = pca9685_id,
573};
574
575module_i2c_driver(pca9685_i2c_driver);
576
577MODULE_AUTHOR("Steffen Trumtrar <s.trumtrar@pengutronix.de>");
578MODULE_DESCRIPTION("PWM driver for PCA9685");
579MODULE_LICENSE("GPL");