[PATCH v2 06/13] pwm: sti: Add support for hardware readout

[Boris Brezillon]

Implement ->get_state() to provide support for initial state retrieval.

Signed-off-by: Boris Brezillon <boris.brezil...@free-electrons.com>
---
 drivers/pwm/pwm-sti.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 92abbd5..6300d3e 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -238,6 +238,43 @@ static void sti_pwm_disable(struct pwm_chip *chip, struct 
pwm_device *pwm)
        mutex_unlock(&pc->sti_pwm_lock);
 }
 
+static void sti_pwm_get_state(struct pwm_chip *chip,
+                             struct pwm_device *pwm,
+                             struct pwm_state *state)
+{
+       struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+       unsigned int regval, prescaler;
+       int ret;
+
+       /* The clock has to be enabled to access PWM registers */
+       ret = clk_enable(pc->clk);
+       if (ret) {
+               dev_err(chip->dev, "Failed to enable PWM clk");
+               return;
+       }
+
+       regmap_field_read(pc->prescale_high, &regval);
+       prescaler = regval << 4;
+       regmap_field_read(pc->prescale_low, &regval);
+       prescaler |= regval;
+       state->period = DIV_ROUND_CLOSEST_ULL((u64)(prescaler + 1) *
+                                             NSEC_PER_SEC *
+                                             (pc->cdata->max_pwm_cnt + 1),
+                                             pc->clk_rate);
+
+       regmap_read(pc->regmap, STI_DS_REG(pwm->hwpwm), &regval);
+       state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)(regval + 1) *
+                                                 state->period,
+                                                 pc->cdata->max_pwm_cnt + 1);
+
+       regmap_field_read(pc->pwm_en, &regval);
+       state->enabled = regval;
+
+       state->polarity = PWM_POLARITY_NORMAL;
+
+       clk_disable(pc->clk);
+}
+
 static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
        struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
@@ -249,6 +286,7 @@ static const struct pwm_ops sti_pwm_ops = {
        .config = sti_pwm_config,
        .enable = sti_pwm_enable,
        .disable = sti_pwm_disable,
+       .get_state = sti_pwm_get_state,
        .free = sti_pwm_free,
        .owner = THIS_MODULE,
 };
-- 
2.7.4