diff options
Diffstat (limited to 'drivers/pwm/pwm-pca9685.c')
| -rw-r--r-- | drivers/pwm/pwm-pca9685.c | 198 |
1 files changed, 159 insertions, 39 deletions
diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c index 7c9f174de64e..42ed770b432c 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 @@ -90,51 +91,120 @@ 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); +} + +static int pca9685_read_reg(struct pca9685 *pca, unsigned int reg, unsigned int *val) +{ + struct device *dev = pca->chip.dev; + 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 pca9685 *pca, unsigned int reg, unsigned int val) +{ + struct device *dev = pca->chip.dev; + 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; +} + /* 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) { + struct pwm_device *pwm = &pca->chip.pwms[channel]; + unsigned int on, off; + if (duty == 0) { /* Set the full OFF bit, which has the highest precedence */ - regmap_write(pca->regmap, REG_OFF_H(channel), LED_FULL); + pca9685_write_reg(pca, REG_OFF_H(channel), LED_FULL); + return; } else if (duty >= PCA9685_COUNTER_RANGE) { /* Set the full ON bit and clear the full OFF bit */ - regmap_write(pca->regmap, REG_ON_H(channel), LED_FULL); - regmap_write(pca->regmap, REG_OFF_H(channel), 0); - } else { - /* Set OFF time (clears the full OFF bit) */ - regmap_write(pca->regmap, REG_OFF_L(channel), duty & 0xff); - regmap_write(pca->regmap, REG_OFF_H(channel), (duty >> 8) & 0xf); - /* Clear the full ON bit */ - regmap_write(pca->regmap, REG_ON_H(channel), 0); + pca9685_write_reg(pca, REG_ON_H(channel), LED_FULL); + pca9685_write_reg(pca, REG_OFF_H(channel), 0); + return; } + + + if (pwm->state.usage_power && channel < PCA9685_MAXCHAN) { + /* + * If usage_power is set, the pca9685 driver will phase shift + * the individual channels relative to their channel number. + * This improves EMI because the enabled channels no longer + * turn on at the same time, while still maintaining the + * configured duty cycle / power output. + */ + on = channel * PCA9685_COUNTER_RANGE / PCA9685_MAXCHAN; + } else + on = 0; + + off = (on + duty) % PCA9685_COUNTER_RANGE; + + /* Set ON time (clears full ON bit) */ + pca9685_write_reg(pca, REG_ON_L(channel), on & 0xff); + pca9685_write_reg(pca, REG_ON_H(channel), (on >> 8) & 0xf); + /* Set OFF time (clears full OFF bit) */ + pca9685_write_reg(pca, REG_OFF_L(channel), off & 0xff); + pca9685_write_reg(pca, REG_OFF_H(channel), (off >> 8) & 0xf); } static unsigned int pca9685_pwm_get_duty(struct pca9685 *pca, int channel) { - unsigned int off_h = 0, val = 0; + struct pwm_device *pwm = &pca->chip.pwms[channel]; + unsigned int off = 0, on = 0, val = 0; if (WARN_ON(channel >= PCA9685_MAXCHAN)) { /* HW does not support reading state of "all LEDs" channel */ return 0; } - regmap_read(pca->regmap, LED_N_OFF_H(channel), &off_h); - if (off_h & LED_FULL) { + pca9685_read_reg(pca, LED_N_OFF_H(channel), &off); + if (off & LED_FULL) { /* Full OFF bit is set */ return 0; } - regmap_read(pca->regmap, LED_N_ON_H(channel), &val); - if (val & LED_FULL) { + pca9685_read_reg(pca, LED_N_ON_H(channel), &on); + if (on & LED_FULL) { /* Full ON bit is set */ return PCA9685_COUNTER_RANGE; } - if (regmap_read(pca->regmap, LED_N_OFF_L(channel), &val)) { - /* Reset val to 0 in case reading LED_N_OFF_L failed */ + pca9685_read_reg(pca, LED_N_OFF_L(channel), &val); + off = ((off & 0xf) << 8) | (val & 0xff); + if (!pwm->state.usage_power) + return off; + + /* Read ON register to calculate duty cycle of staggered output */ + if (pca9685_read_reg(pca, LED_N_ON_L(channel), &val)) { + /* Reset val to 0 in case reading LED_N_ON_L failed */ val = 0; } - return ((off_h & 0xf) << 8) | (val & 0xff); + on = ((on & 0xf) << 8) | (val & 0xff); + return (off - on) & (PCA9685_COUNTER_RANGE - 1); } #if IS_ENABLED(CONFIG_GPIOLIB) @@ -240,8 +310,6 @@ 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; @@ -277,16 +345,23 @@ static inline int pca9685_pwm_gpio_probe(struct pca9685 *pca) static void pca9685_set_sleep_mode(struct pca9685 *pca, bool enable) { - regmap_update_bits(pca->regmap, PCA9685_MODE1, - MODE1_SLEEP, enable ? MODE1_SLEEP : 0); + struct device *dev = pca->chip.dev; + int err = regmap_update_bits(pca->regmap, PCA9685_MODE1, + MODE1_SLEEP, enable ? MODE1_SLEEP : 0); + if (err) { + dev_err(dev, "regmap_update_bits of register 0x%x failed: %pe\n", + PCA9685_MODE1, ERR_PTR(err)); + return; + } + if (!enable) { /* Wait 500us for the oscillator to be back up */ udelay(500); } } -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; @@ -307,8 +382,14 @@ static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, return 0; } - regmap_read(pca->regmap, PCA9685_PRESCALE, &val); + pca9685_read_reg(pca, 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 @@ -319,7 +400,7 @@ static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, pca9685_set_sleep_mode(pca, true); /* Change the chip-wide output frequency */ - regmap_write(pca->regmap, PCA9685_PRESCALE, prescale); + pca9685_write_reg(pca, PCA9685_PRESCALE, prescale); /* Wake the chip up */ pca9685_set_sleep_mode(pca, false); @@ -331,6 +412,25 @@ 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) { @@ -339,7 +439,7 @@ static void pca9685_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, unsigned int val = 0; /* Calculate (chip-wide) period from prescale value */ - regmap_read(pca->regmap, PCA9685_PRESCALE, &val); + pca9685_read_reg(pca, PCA9685_PRESCALE, &val); /* * PCA9685_OSC_CLOCK_MHZ is 25, i.e. an integer divider of 1000. * The following calculation is therefore only a multiplication @@ -372,6 +472,14 @@ 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; @@ -381,7 +489,11 @@ 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); } @@ -422,7 +534,11 @@ static int pca9685_pwm_probe(struct i2c_client *client, i2c_set_clientdata(client, pca); - regmap_read(pca->regmap, PCA9685_MODE2, ®); + mutex_init(&pca->lock); + + ret = pca9685_read_reg(pca, PCA9685_MODE2, ®); + if (ret) + return ret; if (device_property_read_bool(&client->dev, "invert")) reg |= MODE2_INVRT; @@ -434,16 +550,20 @@ static int pca9685_pwm_probe(struct i2c_client *client, else reg |= MODE2_OUTDRV; - regmap_write(pca->regmap, PCA9685_MODE2, reg); + ret = pca9685_write_reg(pca, PCA9685_MODE2, reg); + if (ret) + return ret; /* Disable all LED ALLCALL and SUBx addresses to avoid bus collisions */ - regmap_read(pca->regmap, PCA9685_MODE1, ®); + pca9685_read_reg(pca, PCA9685_MODE1, ®); reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3); - regmap_write(pca->regmap, PCA9685_MODE1, reg); + pca9685_write_reg(pca, PCA9685_MODE1, reg); - /* Reset OFF registers to POR default */ - regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, LED_FULL); - regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, LED_FULL); + /* Reset OFF/ON registers to POR default */ + pca9685_write_reg(pca, PCA9685_ALL_LED_OFF_L, LED_FULL); + pca9685_write_reg(pca, PCA9685_ALL_LED_OFF_H, LED_FULL); + pca9685_write_reg(pca, PCA9685_ALL_LED_ON_L, 0); + pca9685_write_reg(pca, PCA9685_ALL_LED_ON_H, 0); pca->chip.ops = &pca9685_pwm_ops; /* Add an extra channel for ALL_LED */ |