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pwm: rcar: Add support "atomic" API

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This patch adds support for "atomic" API. This behavior differs with
legacy APIs a little.

 Legacy APIs:
  The PWMCNT register will be updated in rcar_pwm_config() even if
  the PWM state is disabled.

 Atomic API:
  The PWMCNT register will be updated in rcar_pwm_apply() only if
  the PWM state is enabled. Otherwize, if a PWM runs with 30% duty
  cycles and the pwm_apply_state() is called with state->enabled = 0,
  ->duty_cycle = 60 and ->period = 100, this is possible to output
  a 60% duty cycle.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Yoshihiro Shimoda 2019-01-09 17:19:05 +09:00 committed by Thierry Reding
parent 74d0c3b205
commit 7f68ce8287
1 changed files with 37 additions and 0 deletions
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37
drivers/pwm/pwm-rcar.c
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@ -192,12 +192,49 @@ static void rcar_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
rcar_pwm_update(rp, RCAR_PWMCR_EN0, 0, RCAR_PWMCR);
}
static int rcar_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct rcar_pwm_chip *rp = to_rcar_pwm_chip(chip);
struct pwm_state cur_state;
int div, ret;
/* This HW/driver only supports normal polarity */
pwm_get_state(pwm, &cur_state);
if (state->polarity != PWM_POLARITY_NORMAL)
return -ENOTSUPP;
if (!state->enabled) {
rcar_pwm_disable(chip, pwm);
return 0;
}
div = rcar_pwm_get_clock_division(rp, state->period);
if (div < 0)
return div;
rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR);
ret = rcar_pwm_set_counter(rp, div, state->duty_cycle, state->period);
if (!ret)
rcar_pwm_set_clock_control(rp, div);
/* The SYNC should be set to 0 even if rcar_pwm_set_counter failed */
rcar_pwm_update(rp, RCAR_PWMCR_SYNC, 0, RCAR_PWMCR);
if (!ret && state->enabled)
ret = rcar_pwm_enable(chip, pwm);
return ret;
}
static const struct pwm_ops rcar_pwm_ops = {
.request = rcar_pwm_request,
.free = rcar_pwm_free,
.config = rcar_pwm_config,
.enable = rcar_pwm_enable,
.disable = rcar_pwm_disable,
.apply = rcar_pwm_apply,
.owner = THIS_MODULE,
};