[PATCH v2] pwm: bcm2835: Support apply function for atomic configuration

From: Lino Sanfilippo
Date: Sat Nov 28 2020 - 17:02:45 EST


Use the newer apply function of pwm_ops instead of config, enable, disable
and set_polarity.

This guarantees atomic changes of the pwm controller configuration. It also
reduces the size of the driver.

This has been tested on a Raspberry PI 4.

v2: Fixed compiler error

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@xxxxxx>
---
drivers/pwm/pwm-bcm2835.c | 64 ++++++++++++++++-------------------------------
1 file changed, 21 insertions(+), 43 deletions(-)

diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
index 6841dcf..dad7443 100644
--- a/drivers/pwm/pwm-bcm2835.c
+++ b/drivers/pwm/pwm-bcm2835.c
@@ -58,13 +58,14 @@ static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
writel(value, pc->base + PWM_CONTROL);
}

-static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
- int duty_ns, int period_ns)
+static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_state *state)
{
+
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
unsigned long rate = clk_get_rate(pc->clk);
unsigned long scaler;
- u32 period;
+ u32 value;

if (!rate) {
dev_err(pc->dev, "failed to get clock rate\n");
@@ -72,65 +73,42 @@ static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
}

scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
- period = DIV_ROUND_CLOSEST(period_ns, scaler);
+ /* set period */
+ value = DIV_ROUND_CLOSEST_ULL(state->period, scaler);

- if (period < PERIOD_MIN)
+ if (value < PERIOD_MIN)
return -EINVAL;

- writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
- pc->base + DUTY(pwm->hwpwm));
- writel(period, pc->base + PERIOD(pwm->hwpwm));
-
- return 0;
-}
+ writel(value, pc->base + PERIOD(pwm->hwpwm));

-static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
- u32 value;
+ /* set duty cycle */
+ value = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
+ writel(value, pc->base + DUTY(pwm->hwpwm));

+ /* set polarity */
value = readl(pc->base + PWM_CONTROL);
- value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
- writel(value, pc->base + PWM_CONTROL);
-
- return 0;
-}

-static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
- u32 value;
-
- value = readl(pc->base + PWM_CONTROL);
- value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
- writel(value, pc->base + PWM_CONTROL);
-}
-
-static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
- enum pwm_polarity polarity)
-{
- struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
- u32 value;
-
- value = readl(pc->base + PWM_CONTROL);
-
- if (polarity == PWM_POLARITY_NORMAL)
+ if (state->polarity == PWM_POLARITY_NORMAL)
value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
else
value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);

+ /* enable/disable */
+ if (state->enabled)
+ value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
+ else
+ value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
+
writel(value, pc->base + PWM_CONTROL);

return 0;
}

+
static const struct pwm_ops bcm2835_pwm_ops = {
.request = bcm2835_pwm_request,
.free = bcm2835_pwm_free,
- .config = bcm2835_pwm_config,
- .enable = bcm2835_pwm_enable,
- .disable = bcm2835_pwm_disable,
- .set_polarity = bcm2835_set_polarity,
+ .apply = bcm2835_pwm_apply,
.owner = THIS_MODULE,
};

--
2.7.4