diff options
| -rw-r--r-- | drivers/pwm/pwm-pca9685.c | 74 |
1 files changed, 64 insertions, 10 deletions
diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c index 20dd579297e6..f70162114197 100644 --- a/drivers/pwm/pwm-pca9685.c +++ b/drivers/pwm/pwm-pca9685.c @@ -23,11 +23,11 @@ #include <linux/bitmap.h> /* - * Because the PCA9685 has only one prescaler per chip, changing the period of - * one channel affects the period of all 16 PWM outputs! - * However, the ratio between each configured duty cycle and the chip-wide - * period remains constant, because the OFF time is set in proportion to the - * counter range. + * 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. + * GPIOs do not count as enabled PWMs as they are not using the prescaler. */ #define PCA9685_MODE1 0x00 @@ -78,8 +78,9 @@ struct pca9685 { struct pwm_chip chip; struct regmap *regmap; -#if IS_ENABLED(CONFIG_GPIOLIB) struct mutex lock; + DECLARE_BITMAP(pwms_enabled, PCA9685_MAXCHAN + 1); +#if IS_ENABLED(CONFIG_GPIOLIB) struct gpio_chip gpio; DECLARE_BITMAP(pwms_inuse, PCA9685_MAXCHAN + 1); #endif @@ -90,6 +91,22 @@ static inline struct pca9685 *to_pca(struct pwm_chip *chip) return container_of(chip, struct pca9685, 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); +} + /* Helper function to set the duty cycle ratio to duty/4096 (e.g. duty=2048 -> 50%) */ static void pca9685_pwm_set_duty(struct pca9685 *pca, int channel, unsigned int duty) { @@ -269,8 +286,6 @@ static int pca9685_pwm_gpio_probe(struct pca9685 *pca) { struct device *dev = pca->chip.dev; - mutex_init(&pca->lock); - pca->gpio.label = dev_name(dev); pca->gpio.parent = dev; pca->gpio.request = pca9685_pwm_gpio_request; @@ -314,8 +329,8 @@ static void pca9685_set_sleep_mode(struct pca9685 *pca, bool enable) } } -static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, - const struct pwm_state *state) +static int __pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) { struct pca9685 *pca = to_pca(chip); unsigned long long duty, prescale; @@ -338,6 +353,12 @@ static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, regmap_read(pca->regmap, PCA9685_PRESCALE, &val); if (prescale != val) { + if (!pca9685_prescaler_can_change(pca, pwm->hwpwm)) { + dev_err(chip->dev, + "pwm not changed: periods of enabled pwms must match!\n"); + return -EBUSY; + } + /* * Putting the chip briefly into SLEEP mode * at this point won't interfere with the @@ -360,6 +381,25 @@ static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, return 0; } +static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct pca9685 *pca = to_pca(chip); + int ret; + + mutex_lock(&pca->lock); + ret = __pca9685_pwm_apply(chip, pwm, state); + if (ret == 0) { + if (state->enabled) + set_bit(pwm->hwpwm, pca->pwms_enabled); + else + clear_bit(pwm->hwpwm, pca->pwms_enabled); + } + mutex_unlock(&pca->lock); + + return ret; +} + static void pca9685_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { @@ -401,6 +441,14 @@ static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) if (pca9685_pwm_test_and_set_inuse(pca, pwm->hwpwm)) return -EBUSY; + + 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(chip->dev); return 0; @@ -410,7 +458,11 @@ static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) { struct pca9685 *pca = to_pca(chip); + mutex_lock(&pca->lock); pca9685_pwm_set_duty(pca, pwm->hwpwm, 0); + clear_bit(pwm->hwpwm, pca->pwms_enabled); + mutex_unlock(&pca->lock); + pm_runtime_put(chip->dev); pca9685_pwm_clear_inuse(pca, pwm->hwpwm); } @@ -451,6 +503,8 @@ static int pca9685_pwm_probe(struct i2c_client *client, i2c_set_clientdata(client, pca); + mutex_init(&pca->lock); + regmap_read(pca->regmap, PCA9685_MODE2, ®); if (device_property_read_bool(&client->dev, "invert")) |