Commit c97267ae authored by Lee Jones's avatar Lee Jones Committed by Thierry Reding
Browse files

pwm: sti: Add PWM capture callback 



Once a PWM capture has been initiated, the capture call enables a rising
edge detection interrupt, then waits. Once each of the 3 phase changes
have been recorded the thread then wakes. The remaining part of the call
carries out the relevant calculations and returns a structure filled out
with the capture data.

Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 25eb5380

drivers/pwm/pwm-sti.c

+88 −0
Original line number Diff line number Diff line
@@ -305,7 +305,90 @@ static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 
	clear_bit(pwm->hwpwm, &pc->configured);

}



static int sti_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm,

			   struct pwm_capture *result, unsigned long timeout)

{

	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);

	struct sti_pwm_compat_data *cdata = pc->cdata;

	struct sti_cpt_ddata *ddata = pwm_get_chip_data(pwm);

	struct device *dev = pc->dev;

	unsigned int effective_ticks;

	unsigned long long high, low;

	int ret;



	if (pwm->hwpwm >= cdata->cpt_num_devs) {

		dev_err(dev, "device %u is not valid\n", pwm->hwpwm);

		return -EINVAL;

	}



	mutex_lock(&ddata->lock);

	ddata->index = 0;



	/* Prepare capture measurement */

	regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_RISING);

	regmap_field_write(pc->pwm_cpt_int_en, BIT(pwm->hwpwm));



	/* Enable capture */

	ret = regmap_field_write(pc->pwm_cpt_en, 1);

	if (ret) {

		dev_err(dev, "failed to enable PWM capture %u: %d\n",

			pwm->hwpwm, ret);

		goto out;

	}



	ret = wait_event_interruptible_timeout(ddata->wait, ddata->index > 1,

					       msecs_to_jiffies(timeout));



	regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_DISABLED);



	if (ret == -ERESTARTSYS)

		goto out;



	switch (ddata->index) {

	case 0:

	case 1:

		/*

		 * Getting here could mean:

		 *  - input signal is constant of less than 1 Hz

		 *  - there is no input signal at all

		 *

		 * In such case the frequency is rounded down to 0

		 */

		result->period = 0;

		result->duty_cycle = 0;



		break;



	case 2:

		/* We have everying we need */

		high = ddata->snapshot[1] - ddata->snapshot[0];

		low = ddata->snapshot[2] - ddata->snapshot[1];



		effective_ticks = clk_get_rate(pc->cpt_clk);



		result->period = (high + low) * NSEC_PER_SEC;

		result->period /= effective_ticks;



		result->duty_cycle = high * NSEC_PER_SEC;

		result->duty_cycle /= effective_ticks;



		break;



	default:

		dev_err(dev, "internal error\n");

		break;

	}



out:

	/* Disable capture */

	regmap_field_write(pc->pwm_cpt_en, 0);



	mutex_unlock(&ddata->lock);

	return ret;

}



static const struct pwm_ops sti_pwm_ops = {

	.capture = sti_pwm_capture,

	.config = sti_pwm_config,

	.enable = sti_pwm_enable,

	.disable = sti_pwm_disable,
@@ -418,6 +501,11 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc) 
	if (IS_ERR(pc->pwm_out_en))

		return PTR_ERR(pc->pwm_out_en);



	pc->pwm_cpt_en = devm_regmap_field_alloc(dev, pc->regmap,

						 reg_fields[PWM_CPT_EN]);

	if (IS_ERR(pc->pwm_cpt_en))

		return PTR_ERR(pc->pwm_cpt_en);



	pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,

						 reg_fields[PWM_CPT_INT_EN]);

	if (IS_ERR(pc->pwm_cpt_int_en))

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