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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: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Lee Jones 2016-08-16 10:35:05 +01:00 committed by Thierry Reding
parent 25eb538096
commit c97267ae83
1 changed files with 88 additions and 0 deletions
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88
drivers/pwm/pwm-sti.c
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@ -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))