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linux/drivers/pwm/pwm-pca9685.c
Uwe Kleine-König ce11164460 pwm: pca9586: Convert to waveform API 
This allows to expose the duty_offset feature that the chip supports, and
so also emit inverted polarity waveforms. The conversion from a waveform to
hardware settings (and vice versa) is aligned to the usual rounding rules
silencing warnings with PWM_DEBUG.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/1927d115ae6797858e6c4537971dacf1d563854f.1753784092.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
2025-09-15 11:39:46 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for PCA9685 16-channel 12-bit PWM LED controller
*
* Copyright (C) 2013 Steffen Trumtrar <s.trumtrar@pengutronix.de>
* Copyright (C) 2015 Clemens Gruber <clemens.gruber@pqgruber.com>
*
* based on the pwm-twl-led.c driver
*/
#include <linux/gpio/driver.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/pm_runtime.h>
#include <linux/bitmap.h>
/*
* Because the PCA9685 has only one prescaler per chip, only the first channel
* that is enabled is allowed to change the prescale register.
* PWM channels requested afterwards must use a period that results in the same
* prescale setting as the one set by the first requested channel.
*/
#define PCA9685_MODE1 0x00
#define PCA9685_MODE2 0x01
#define PCA9685_SUBADDR1 0x02
#define PCA9685_SUBADDR2 0x03
#define PCA9685_SUBADDR3 0x04
#define PCA9685_ALLCALLADDR 0x05
#define PCA9685_LEDX_ON_L 0x06
#define PCA9685_LEDX_ON_H 0x07
#define PCA9685_LEDX_OFF_L 0x08
#define PCA9685_LEDX_OFF_H 0x09
#define PCA9685_ALL_LED_ON_L 0xFA
#define PCA9685_ALL_LED_ON_H 0xFB
#define PCA9685_ALL_LED_OFF_L 0xFC
#define PCA9685_ALL_LED_OFF_H 0xFD
#define PCA9685_PRESCALE 0xFE
#define PCA9685_PRESCALE_MIN 0x03 /* => max. frequency of 1526 Hz */
#define PCA9685_PRESCALE_MAX 0xFF /* => min. frequency of 24 Hz */
#define PCA9685_COUNTER_RANGE 4096
#define PCA9685_OSC_CLOCK_HZ 25000000 /* Internal oscillator with 25 MHz */
/*
* The time value of one counter tick. Note that NSEC_PER_SEC is an integer
* multiple of PCA9685_OSC_CLOCK_HZ, so there is no rounding involved and we're
* not loosing precision due to the early division.
*/
#define PCA9685_QUANTUM_NS(_prescale) ((NSEC_PER_SEC / PCA9685_OSC_CLOCK_HZ) * (_prescale + 1))
#define PCA9685_NUMREGS 0xFF
#define PCA9685_MAXCHAN 0x10
#define LED_FULL BIT(4)
#define MODE1_ALLCALL BIT(0)
#define MODE1_SUB3 BIT(1)
#define MODE1_SUB2 BIT(2)
#define MODE1_SUB1 BIT(3)
#define MODE1_SLEEP BIT(4)
#define MODE1_AI BIT(5)
#define MODE2_INVRT BIT(4)
#define MODE2_OUTDRV BIT(2)
#define LED_N_ON_H(N) (PCA9685_LEDX_ON_H + (4 * (N)))
#define LED_N_ON_L(N) (PCA9685_LEDX_ON_L + (4 * (N)))
#define LED_N_OFF_H(N) (PCA9685_LEDX_OFF_H + (4 * (N)))
#define LED_N_OFF_L(N) (PCA9685_LEDX_OFF_L + (4 * (N)))
#define REG_ON_H(C) ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_ON_H : LED_N_ON_H((C)))
#define REG_ON_L(C) ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_ON_L : LED_N_ON_L((C)))
#define REG_OFF_H(C) ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_OFF_H : LED_N_OFF_H((C)))
#define REG_OFF_L(C) ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_OFF_L : LED_N_OFF_L((C)))
struct pca9685 {
struct regmap *regmap;
struct mutex lock;
DECLARE_BITMAP(pwms_enabled, PCA9685_MAXCHAN + 1);
};
static inline struct pca9685 *to_pca(struct pwm_chip *chip)
{
return pwmchip_get_drvdata(chip);
}
/* This function is supposed to be called with the lock mutex held */
static bool pca9685_prescaler_can_change(struct pca9685 *pca, int channel)
{
/* No PWM enabled: Change allowed */
if (bitmap_empty(pca->pwms_enabled, PCA9685_MAXCHAN + 1))
return true;
/* More than one PWM enabled: Change not allowed */
if (bitmap_weight(pca->pwms_enabled, PCA9685_MAXCHAN + 1) > 1)
return false;
/*
* Only one PWM enabled: Change allowed if the PWM about to
* be changed is the one that is already enabled
*/
return test_bit(channel, pca->pwms_enabled);
}
static int pca9685_read_reg(struct pwm_chip *chip, unsigned int reg, unsigned int *val)
{
struct pca9685 *pca = to_pca(chip);
struct device *dev = pwmchip_parent(chip);
int err;
err = regmap_read(pca->regmap, reg, val);
if (err)
dev_err(dev, "regmap_read of register 0x%x failed: %pe\n", reg, ERR_PTR(err));
return err;
}
static int pca9685_write_reg(struct pwm_chip *chip, unsigned int reg, unsigned int val)
{
struct pca9685 *pca = to_pca(chip);
struct device *dev = pwmchip_parent(chip);
int err;
err = regmap_write(pca->regmap, reg, val);
if (err)
dev_err(dev, "regmap_write to register 0x%x failed: %pe\n", reg, ERR_PTR(err));
return err;
}
static int pca9685_write_4reg(struct pwm_chip *chip, unsigned int reg, u8 val[4])
{
struct pca9685 *pca = to_pca(chip);
struct device *dev = pwmchip_parent(chip);
int err;
err = regmap_bulk_write(pca->regmap, reg, val, 4);
if (err)
dev_err(dev, "regmap_write to register 0x%x failed: %pe\n", reg, ERR_PTR(err));
return err;
}
static int pca9685_set_sleep_mode(struct pwm_chip *chip, bool enable)
{
struct pca9685 *pca = to_pca(chip);
int err;
err = regmap_update_bits(pca->regmap, PCA9685_MODE1,
MODE1_SLEEP, enable ? MODE1_SLEEP : 0);
if (err)
return err;
if (!enable) {
/* Wait 500us for the oscillator to be back up */
udelay(500);
}
return 0;
}
struct pca9685_waveform {
u8 onoff[4];
u8 prescale;
};
static int pca9685_round_waveform_tohw(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_waveform *wf, void *_wfhw)
{
struct pca9685_waveform *wfhw = _wfhw;
struct pca9685 *pca = to_pca(chip);
unsigned int best_prescale;
u8 prescale;
unsigned int period_ns, duty;
int ret_tohw = 0;
if (!wf->period_length_ns) {
*wfhw = (typeof(*wfhw)){
.onoff = { 0, 0, 0, LED_FULL, },
.prescale = 0,
};
dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] -> [%hhx %hhx %hhx %hhx] PSC:%hhx\n",
pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale);
return 0;
}
if (wf->period_length_ns >= PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(255)) {
best_prescale = 255;
} else if (wf->period_length_ns < PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(3)) {
best_prescale = 3;
ret_tohw = 1;
} else {
best_prescale = (unsigned int)wf->period_length_ns / (PCA9685_COUNTER_RANGE * (NSEC_PER_SEC / PCA9685_OSC_CLOCK_HZ)) - 1;
}
guard(mutex)(&pca->lock);
if (!pca9685_prescaler_can_change(pca, pwm->hwpwm)) {
unsigned int current_prescale;
int ret;
ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &current_prescale);
if (ret)
return ret;
if (current_prescale > best_prescale)
ret_tohw = 1;
prescale = current_prescale;
} else {
prescale = best_prescale;
}
period_ns = PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);
duty = (unsigned)min_t(u64, wf->duty_length_ns, period_ns) / PCA9685_QUANTUM_NS(prescale);
if (duty < PCA9685_COUNTER_RANGE) {
unsigned int on, off;
on = (unsigned)min_t(u64, wf->duty_offset_ns, period_ns) / PCA9685_QUANTUM_NS(prescale);
off = (on + duty) % PCA9685_COUNTER_RANGE;
/*
* With a zero duty cycle, it doesn't matter if period was
* rounded up
*/
if (!duty)
ret_tohw = 0;
*wfhw = (typeof(*wfhw)){
.onoff = { on & 0xff, (on >> 8) & 0xf, off & 0xff, (off >> 8) & 0xf },
.prescale = prescale,
};
} else {
*wfhw = (typeof(*wfhw)){
.onoff = { 0, LED_FULL, 0, 0, },
.prescale = prescale,
};
}
dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] -> %s[%hhx %hhx %hhx %hhx] PSC:%hhx\n",
pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
ret_tohw ? "#" : "", wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale);
return ret_tohw;
}
static int pca9685_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,
const void *_wfhw, struct pwm_waveform *wf)
{
const struct pca9685_waveform *wfhw = _wfhw;
struct pca9685 *pca = to_pca(chip);
unsigned int prescale;
if (wfhw->prescale)
prescale = wfhw->prescale;
else
scoped_guard(mutex, &pca->lock) {
int ret;
ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &prescale);
if (ret)
return ret;
}
wf->period_length_ns = PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);
if (wfhw->onoff[3] & LED_FULL) {
wf->duty_length_ns = 0;
wf->duty_offset_ns = 0;
} else if (wfhw->onoff[1] & LED_FULL) {
wf->duty_length_ns = wf->period_length_ns;
wf->duty_offset_ns = 0;
} else {
unsigned int on = wfhw->onoff[0] | (wfhw->onoff[1] & 0xf) << 8;
unsigned int off = wfhw->onoff[2] | (wfhw->onoff[3] & 0xf) << 8;
wf->duty_length_ns = (off - on) % PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);
wf->duty_offset_ns = on * PCA9685_QUANTUM_NS(prescale);
}
dev_dbg(&chip->dev, "pwm#%u: [%hhx %hhx %hhx %hhx] PSC:%hhx -> %lld/%lld [+%lld]\n",
pwm->hwpwm,
wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale,
wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns);
return 0;
}
static int pca9685_read_waveform(struct pwm_chip *chip, struct pwm_device *pwm, void *_wfhw)
{
struct pca9685_waveform *wfhw = _wfhw;
struct pca9685 *pca = to_pca(chip);
unsigned int prescale;
int ret;
guard(mutex)(&pca->lock);
ret = regmap_bulk_read(pca->regmap, REG_ON_L(pwm->hwpwm), &wfhw->onoff, 4);
if (ret)
return ret;
ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &prescale);
if (ret)
return ret;
wfhw->prescale = prescale;
return 0;
}
static int pca9685_write_waveform(struct pwm_chip *chip, struct pwm_device *pwm, const void *_wfhw)
{
const struct pca9685_waveform *wfhw = _wfhw;
struct pca9685 *pca = to_pca(chip);
unsigned int current_prescale;
int ret;
guard(mutex)(&pca->lock);
if (wfhw->prescale) {
ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &current_prescale);
if (ret)
return ret;
if (current_prescale != wfhw->prescale) {
if (!pca9685_prescaler_can_change(pca, pwm->hwpwm))
return -EBUSY;
/* Put chip into sleep mode */
ret = pca9685_set_sleep_mode(chip, true);
if (ret)
return ret;
/* Change the chip-wide output frequency */
ret = regmap_write(pca->regmap, PCA9685_PRESCALE, wfhw->prescale);
if (ret)
return ret;
/* Wake the chip up */
ret = pca9685_set_sleep_mode(chip, false);
if (ret)
return ret;
}
}
return regmap_bulk_write(pca->regmap, REG_ON_L(pwm->hwpwm), &wfhw->onoff, 4);
}
static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
if (pwm->hwpwm < PCA9685_MAXCHAN) {
/* PWMs - except the "all LEDs" channel - default to enabled */
mutex_lock(&pca->lock);
set_bit(pwm->hwpwm, pca->pwms_enabled);
mutex_unlock(&pca->lock);
}
pm_runtime_get_sync(pwmchip_parent(chip));
return 0;
}
static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
mutex_lock(&pca->lock);
clear_bit(pwm->hwpwm, pca->pwms_enabled);
mutex_unlock(&pca->lock);
pm_runtime_put(pwmchip_parent(chip));
}
static const struct pwm_ops pca9685_pwm_ops = {
.sizeof_wfhw = sizeof(struct pca9685_waveform),
.round_waveform_tohw = pca9685_round_waveform_tohw,
.round_waveform_fromhw = pca9685_round_waveform_fromhw,
.read_waveform = pca9685_read_waveform,
.write_waveform = pca9685_write_waveform,
.request = pca9685_pwm_request,
.free = pca9685_pwm_free,
};
static bool pca9685_readable_reg(struct device *dev, unsigned int reg)
{
/* The ALL_LED registers are readable but read as zero */
return reg <= REG_OFF_H(15) || reg >= PCA9685_PRESCALE;
}
static bool pca9685_writeable_reg(struct device *dev, unsigned int reg)
{
return reg <= REG_OFF_H(15) || reg >= PCA9685_ALL_LED_ON_L;
}
static bool pca9685_volatile_reg(struct device *dev, unsigned int reg)
{
/*
* Writing to an ALL_LED register affects all LEDi registers, so they
* are not cachable. :-\
*/
return reg < PCA9685_PRESCALE;
}
static const struct regmap_config pca9685_regmap_i2c_config = {
.reg_bits = 8,
.val_bits = 8,
.readable_reg = pca9685_readable_reg,
.writeable_reg = pca9685_writeable_reg,
.volatile_reg = pca9685_volatile_reg,
.max_register = PCA9685_NUMREGS,
.cache_type = REGCACHE_MAPLE,
};
static int pca9685_pwm_probe(struct i2c_client *client)
{
struct pwm_chip *chip;
struct pca9685 *pca;
unsigned int reg;
int ret;
/* Add an extra channel for ALL_LED */
chip = devm_pwmchip_alloc(&client->dev, PCA9685_MAXCHAN + 1, sizeof(*pca));
if (IS_ERR(chip))
return PTR_ERR(chip);
pca = to_pca(chip);
pca->regmap = devm_regmap_init_i2c(client, &pca9685_regmap_i2c_config);
if (IS_ERR(pca->regmap)) {
ret = PTR_ERR(pca->regmap);
dev_err(&client->dev, "Failed to initialize register map: %d\n",
ret);
return ret;
}
i2c_set_clientdata(client, chip);
mutex_init(&pca->lock);
/* clear MODE2_OCH */
reg = 0;
if (device_property_read_bool(&client->dev, "invert"))
reg |= MODE2_INVRT;
else
reg &= ~MODE2_INVRT;
if (device_property_read_bool(&client->dev, "open-drain"))
reg &= ~MODE2_OUTDRV;
else
reg |= MODE2_OUTDRV;
ret = pca9685_write_reg(chip, PCA9685_MODE2, reg);
if (ret)
return ret;
/*
* Disable all LED ALLCALL and SUBx addresses to avoid bus collisions,
* enable Auto-Increment.
*/
pca9685_read_reg(chip, PCA9685_MODE1, &reg);
reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
reg |= MODE1_AI;
pca9685_write_reg(chip, PCA9685_MODE1, reg);
/* Reset OFF/ON registers to POR default */
ret = pca9685_write_4reg(chip, PCA9685_ALL_LED_ON_L, (u8[]){ 0, LED_FULL, 0, LED_FULL });
if (ret < 0)
return dev_err_probe(&client->dev, ret, "Failed to reset ON/OFF registers\n");
chip->ops = &pca9685_pwm_ops;
ret = pwmchip_add(chip);
if (ret < 0)
return ret;
pm_runtime_enable(&client->dev);
if (pm_runtime_enabled(&client->dev)) {
/*
* Although the chip comes out of power-up in the sleep state,
* we force it to sleep in case it was woken up before
*/
pca9685_set_sleep_mode(chip, true);
pm_runtime_set_suspended(&client->dev);
} else {
/* Wake the chip up if runtime PM is disabled */
pca9685_set_sleep_mode(chip, false);
}
return 0;
}
static void pca9685_pwm_remove(struct i2c_client *client)
{
struct pwm_chip *chip = i2c_get_clientdata(client);
pwmchip_remove(chip);
if (!pm_runtime_enabled(&client->dev)) {
/* Put chip in sleep state if runtime PM is disabled */
pca9685_set_sleep_mode(chip, true);
}
pm_runtime_disable(&client->dev);
}
static int __maybe_unused pca9685_pwm_runtime_suspend(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct pwm_chip *chip = i2c_get_clientdata(client);
pca9685_set_sleep_mode(chip, true);
return 0;
}
static int __maybe_unused pca9685_pwm_runtime_resume(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct pwm_chip *chip = i2c_get_clientdata(client);
pca9685_set_sleep_mode(chip, false);
return 0;
}
static const struct i2c_device_id pca9685_id[] = {
{ "pca9685" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, pca9685_id);
static const struct acpi_device_id pca9685_acpi_ids[] = {
{ "INT3492", 0 },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(acpi, pca9685_acpi_ids);
static const struct of_device_id pca9685_dt_ids[] = {
{ .compatible = "nxp,pca9685-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pca9685_dt_ids);
static const struct dev_pm_ops pca9685_pwm_pm = {
SET_RUNTIME_PM_OPS(pca9685_pwm_runtime_suspend,
pca9685_pwm_runtime_resume, NULL)
};
static struct i2c_driver pca9685_i2c_driver = {
.driver = {
.name = "pca9685-pwm",
.acpi_match_table = pca9685_acpi_ids,
.of_match_table = pca9685_dt_ids,
.pm = &pca9685_pwm_pm,
},
.probe = pca9685_pwm_probe,
.remove = pca9685_pwm_remove,
.id_table = pca9685_id,
};
module_i2c_driver(pca9685_i2c_driver);
MODULE_AUTHOR("Steffen Trumtrar <s.trumtrar@pengutronix.de>");
MODULE_DESCRIPTION("PWM driver for PCA9685");
MODULE_LICENSE("GPL");
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