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>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index a41812fc6f95..e3ab663ff3a7 100644
--- 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,
 };