Commit 2f81b51d authored by Lino Sanfilippo's avatar Lino Sanfilippo Committed by Thierry Reding
Browse files

pwm: bcm2835: Support apply function for atomic configuration 



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.

Since now period is a 64 bit value, add an extra check to reject periods
that exceed the possible max value for the 32 bit register.

This has been tested on a Raspberry PI 4.

Signed-off-by: default avatarLino Sanfilippo <LinoSanfilippo@gmx.de>
Reviewed-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent bb72e1db

drivers/pwm/pwm-bcm2835.c

+24 −45
Original line number Diff line number Diff line
@@ -58,13 +58,15 @@ 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 long period;

	unsigned long scaler;

	u32 period;

	u32 val;



	if (!rate) {

		dev_err(pc->dev, "failed to get clock rate\n");
@@ -72,54 +74,34 @@ 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 */

	period = DIV_ROUND_CLOSEST_ULL(state->period, scaler);



	if (period < PERIOD_MIN)

	/* dont accept a period that is too small or has been truncated */

	if ((period < PERIOD_MIN) || (period > U32_MAX))

		return -EINVAL;



	writel(DIV_ROUND_CLOSEST(duty_ns, scaler),

	       pc->base + DUTY(pwm->hwpwm));

	writel(period, pc->base + PERIOD(pwm->hwpwm));



	return 0;

}



static int bcm2835_pwm_enable(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);

	/* set duty cycle */

	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);

	writel(val, pc->base + DUTY(pwm->hwpwm));



	return 0;

}

	/* set polarity */

	val = readl(pc->base + PWM_CONTROL);



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 (state->polarity == PWM_POLARITY_NORMAL)

		val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));

	else

		val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);



	if (polarity == PWM_POLARITY_NORMAL)

		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));

	/* enable/disable */

	if (state->enabled)

		val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);

	else

		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);

		val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));



	writel(value, pc->base + PWM_CONTROL);

	writel(val, pc->base + PWM_CONTROL);



	return 0;

}
@@ -127,10 +109,7 @@ static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, 
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,

};