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authorClemens Gruber <clemens.gruber@pqgruber.com>2021-04-15 14:14:48 +0200
committerThierry Reding <thierry.reding@gmail.com>2021-04-23 18:44:55 +0200
commit9af1fba33b5751d71c0e6727a875b9fd7d8a99de (patch)
tree0696057e620fb2715c380d3cafc169723bdaccbf /drivers/pwm
parent64d7d074acd52e1bdff621f2cb86c0aae9bcef80 (diff)
pwm: pca9685: Switch to atomic API
The switch to the atomic API goes hand in hand with a few fixes to previously experienced issues: - The duty cycle is no longer lost after disable/enable (previously the OFF registers were cleared in disable and the user was required to call config to restore the duty cycle settings) - If one sets a period resulting in the same prescale register value, the sleep and write to the register is now skipped - Previously, only the full ON bit was toggled in GPIO mode (and full OFF cleared if set to high), which could result in both full OFF and full ON not being set and on=0, off=0, which is not allowed according to the datasheet - The OFF registers were reset to 0 in probe, which could lead to the forbidden on=0, off=0. Fixed by resetting to POR default (full OFF) Signed-off-by: Clemens Gruber <clemens.gruber@pqgruber.com> Acked-by: Uwe Kleine-K├Ânig <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
-rw-r--r--drivers/pwm/pwm-pca9685.c261
1 files changed, 91 insertions, 170 deletions
diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index 00976b2c57b2..b740b824bda9 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -51,7 +51,6 @@
#define PCA9685_PRESCALE_MAX 0xFF /* => min. frequency of 24 Hz */
#define PCA9685_COUNTER_RANGE 4096
-#define PCA9685_DEFAULT_PERIOD 5000000 /* Default period_ns = 1/200 Hz */
#define PCA9685_OSC_CLOCK_MHZ 25 /* Internal oscillator with 25 MHz */
#define PCA9685_NUMREGS 0xFF
@@ -71,10 +70,14 @@
#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 pwm_chip chip;
struct regmap *regmap;
- int period_ns;
#if IS_ENABLED(CONFIG_GPIOLIB)
struct mutex lock;
struct gpio_chip gpio;
@@ -87,6 +90,53 @@ static inline struct pca9685 *to_pca(struct pwm_chip *chip)
return container_of(chip, struct pca9685, chip);
}
+/* 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)
+{
+ if (duty == 0) {
+ /* Set the full OFF bit, which has the highest precedence */
+ regmap_write(pca->regmap, REG_OFF_H(channel), LED_FULL);
+ } 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);
+ }
+}
+
+static unsigned int pca9685_pwm_get_duty(struct pca9685 *pca, int channel)
+{
+ unsigned int off_h = 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) {
+ /* Full OFF bit is set */
+ return 0;
+ }
+
+ regmap_read(pca->regmap, LED_N_ON_H(channel), &val);
+ if (val & 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 */
+ val = 0;
+ }
+ return ((off_h & 0xf) << 8) | (val & 0xff);
+}
+
#if IS_ENABLED(CONFIG_GPIOLIB)
static bool pca9685_pwm_test_and_set_inuse(struct pca9685 *pca, int pwm_idx)
{
@@ -138,34 +188,23 @@ static int pca9685_pwm_gpio_request(struct gpio_chip *gpio, unsigned int offset)
static int pca9685_pwm_gpio_get(struct gpio_chip *gpio, unsigned int offset)
{
struct pca9685 *pca = gpiochip_get_data(gpio);
- struct pwm_device *pwm = &pca->chip.pwms[offset];
- unsigned int value;
- regmap_read(pca->regmap, LED_N_ON_H(pwm->hwpwm), &value);
-
- return value & LED_FULL;
+ return pca9685_pwm_get_duty(pca, offset) != 0;
}
static void pca9685_pwm_gpio_set(struct gpio_chip *gpio, unsigned int offset,
int value)
{
struct pca9685 *pca = gpiochip_get_data(gpio);
- struct pwm_device *pwm = &pca->chip.pwms[offset];
- unsigned int on = value ? LED_FULL : 0;
-
- /* Clear both OFF registers */
- regmap_write(pca->regmap, LED_N_OFF_L(pwm->hwpwm), 0);
- regmap_write(pca->regmap, LED_N_OFF_H(pwm->hwpwm), 0);
- /* Set the full ON bit */
- regmap_write(pca->regmap, LED_N_ON_H(pwm->hwpwm), on);
+ pca9685_pwm_set_duty(pca, offset, value ? PCA9685_COUNTER_RANGE : 0);
}
static void pca9685_pwm_gpio_free(struct gpio_chip *gpio, unsigned int offset)
{
struct pca9685 *pca = gpiochip_get_data(gpio);
- pca9685_pwm_gpio_set(gpio, offset, 0);
+ pca9685_pwm_set_duty(pca, offset, 0);
pm_runtime_put(pca->chip.dev);
pca9685_pwm_clear_inuse(pca, offset);
}
@@ -246,167 +285,52 @@ static void pca9685_set_sleep_mode(struct pca9685 *pca, bool enable)
}
}
-static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
- int duty_ns, int period_ns)
+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;
- unsigned int reg;
- int prescale;
-
- if (period_ns != pca->period_ns) {
- prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ * period_ns,
- PCA9685_COUNTER_RANGE * 1000) - 1;
-
- if (prescale >= PCA9685_PRESCALE_MIN &&
- prescale <= PCA9685_PRESCALE_MAX) {
- /*
- * Putting the chip briefly into SLEEP mode
- * at this point won't interfere with the
- * pm_runtime framework, because the pm_runtime
- * state is guaranteed active here.
- */
- /* Put chip into sleep mode */
- pca9685_set_sleep_mode(pca, true);
-
- /* Change the chip-wide output frequency */
- regmap_write(pca->regmap, PCA9685_PRESCALE, prescale);
-
- /* Wake the chip up */
- pca9685_set_sleep_mode(pca, false);
-
- pca->period_ns = period_ns;
- } else {
- dev_err(chip->dev,
- "prescaler not set: period out of bounds!\n");
- return -EINVAL;
- }
- }
+ unsigned long long duty, prescale;
+ unsigned int val = 0;
- if (duty_ns < 1) {
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_H;
- else
- reg = LED_N_OFF_H(pwm->hwpwm);
+ if (state->polarity != PWM_POLARITY_NORMAL)
+ return -EINVAL;
- regmap_write(pca->regmap, reg, LED_FULL);
-
- return 0;
+ prescale = DIV_ROUND_CLOSEST_ULL(PCA9685_OSC_CLOCK_MHZ * state->period,
+ PCA9685_COUNTER_RANGE * 1000) - 1;
+ if (prescale < PCA9685_PRESCALE_MIN || prescale > PCA9685_PRESCALE_MAX) {
+ dev_err(chip->dev, "pwm not changed: period out of bounds!\n");
+ return -EINVAL;
}
- if (duty_ns == period_ns) {
- /* Clear both OFF registers */
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_L;
- else
- reg = LED_N_OFF_L(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, 0x0);
-
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_H;
- else
- reg = LED_N_OFF_H(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, 0x0);
-
- /* Set the full ON bit */
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_ON_H;
- else
- reg = LED_N_ON_H(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, LED_FULL);
-
+ if (!state->enabled) {
+ pca9685_pwm_set_duty(pca, pwm->hwpwm, 0);
return 0;
}
- duty = PCA9685_COUNTER_RANGE * (unsigned long long)duty_ns;
- duty = DIV_ROUND_UP_ULL(duty, period_ns);
-
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_L;
- else
- reg = LED_N_OFF_L(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, (int)duty & 0xff);
-
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_H;
- else
- reg = LED_N_OFF_H(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, ((int)duty >> 8) & 0xf);
-
- /* Clear the full ON bit, otherwise the set OFF time has no effect */
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_ON_H;
- else
- reg = LED_N_ON_H(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, 0);
-
- return 0;
-}
-
-static int pca9685_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct pca9685 *pca = to_pca(chip);
- unsigned int reg;
-
- /*
- * The PWM subsystem does not support a pre-delay.
- * So, set the ON-timeout to 0
- */
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_ON_L;
- else
- reg = LED_N_ON_L(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, 0);
-
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_ON_H;
- else
- reg = LED_N_ON_H(pwm->hwpwm);
+ regmap_read(pca->regmap, PCA9685_PRESCALE, &val);
+ if (prescale != val) {
+ /*
+ * Putting the chip briefly into SLEEP mode
+ * at this point won't interfere with the
+ * pm_runtime framework, because the pm_runtime
+ * state is guaranteed active here.
+ */
+ /* Put chip into sleep mode */
+ pca9685_set_sleep_mode(pca, true);
- regmap_write(pca->regmap, reg, 0);
+ /* Change the chip-wide output frequency */
+ regmap_write(pca->regmap, PCA9685_PRESCALE, prescale);
- /*
- * Clear the full-off bit.
- * It has precedence over the others and must be off.
- */
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_H;
- else
- reg = LED_N_OFF_H(pwm->hwpwm);
-
- regmap_update_bits(pca->regmap, reg, LED_FULL, 0x0);
+ /* Wake the chip up */
+ pca9685_set_sleep_mode(pca, false);
+ }
+ duty = PCA9685_COUNTER_RANGE * state->duty_cycle;
+ duty = DIV_ROUND_UP_ULL(duty, state->period);
+ pca9685_pwm_set_duty(pca, pwm->hwpwm, duty);
return 0;
}
-static void pca9685_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct pca9685 *pca = to_pca(chip);
- unsigned int reg;
-
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_H;
- else
- reg = LED_N_OFF_H(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, LED_FULL);
-
- /* Clear the LED_OFF counter. */
- if (pwm->hwpwm >= PCA9685_MAXCHAN)
- reg = PCA9685_ALL_LED_OFF_L;
- else
- reg = LED_N_OFF_L(pwm->hwpwm);
-
- regmap_write(pca->regmap, reg, 0x0);
-}
-
static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
@@ -422,15 +346,13 @@ static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
- pca9685_pwm_disable(chip, pwm);
+ pca9685_pwm_set_duty(pca, pwm->hwpwm, 0);
pm_runtime_put(chip->dev);
pca9685_pwm_clear_inuse(pca, pwm->hwpwm);
}
static const struct pwm_ops pca9685_pwm_ops = {
- .enable = pca9685_pwm_enable,
- .disable = pca9685_pwm_disable,
- .config = pca9685_pwm_config,
+ .apply = pca9685_pwm_apply,
.request = pca9685_pwm_request,
.free = pca9685_pwm_free,
.owner = THIS_MODULE,
@@ -461,7 +383,6 @@ static int pca9685_pwm_probe(struct i2c_client *client,
ret);
return ret;
}
- pca->period_ns = PCA9685_DEFAULT_PERIOD;
i2c_set_clientdata(client, pca);
@@ -484,9 +405,9 @@ static int pca9685_pwm_probe(struct i2c_client *client,
reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
regmap_write(pca->regmap, PCA9685_MODE1, reg);
- /* Clear all "full off" bits */
- regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);
- regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, 0);
+ /* 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);
pca->chip.ops = &pca9685_pwm_ops;
/* Add an extra channel for ALL_LED */