pwm: rcar: Add support "atomic" API

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>

diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index a41812fc6f95733a2568eb0d6b5c7f44fe5a1741..e3ab663ff3a7783bc9446905e9cbe4c1dbfb61d5 100644 (file)
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -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,
 };