[PATCH] pwm: lpc18xx: Implement .apply() callback

* [PATCH] pwm: lpc18xx: Implement .apply() callback
@ 2022-05-08  9:40 ` Uwe Kleine-König
  0 siblings, 0 replies; 2+ messages in thread
From: Uwe Kleine-König @ 2022-05-08  9:40 UTC (permalink / raw)
  To: Thierry Reding, Lee Jones, Vladimir Zapolskiy
  Cc: linux-pwm, kernel, linux-arm-kernel

To eventually get rid of all legacy drivers convert this driver to the
modern world implementing .apply().
This pushes a variant of pwm_apply_legacy into the driver that was slightly
simplified because the .set_polarity callback was a noop.

There is no change in behavior.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-lpc18xx-sct.c | 43 ++++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 13 deletions(-)

Hello,

note the driver behave as expected when pwm_apply is called with a
polarity change and .enabled = false, because the polarity change is
only implemented in lpc18xx_pwm_enable(). I think this is a theoretic
concern though, because a) this probably never happens and b) because
the behaviour for a disabled PWM isn't formalized anyhow. This problem
exists with and without this patch.

Best regards
Uwe

diff --git a/drivers/pwm/pwm-lpc18xx-sct.c b/drivers/pwm/pwm-lpc18xx-sct.c
index b909096dba2f..272e0b5d01b8 100644
--- a/drivers/pwm/pwm-lpc18xx-sct.c
+++ b/drivers/pwm/pwm-lpc18xx-sct.c
@@ -226,14 +226,7 @@ static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static int lpc18xx_pwm_set_polarity(struct pwm_chip *chip,
-				    struct pwm_device *pwm,
-				    enum pwm_polarity polarity)
-{
-	return 0;
-}
-
-static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
@@ -249,7 +242,7 @@ static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 			   LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
 			   LPC18XX_PWM_EVSTATEMSK_ALL);
 
-	if (pwm_get_polarity(pwm) == PWM_POLARITY_NORMAL) {
+	if (polarity == PWM_POLARITY_NORMAL) {
 		set_event = lpc18xx_pwm->period_event;
 		clear_event = lpc18xx_data->duty_event;
 		res_action = LPC18XX_PWM_RES_SET;
@@ -308,11 +301,35 @@ static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 	clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
 }
 
+static int lpc18xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			     const struct pwm_state *state)
+{
+	int err;
+	bool enabled = pwm->state.enabled;
+
+	if (state->polarity != pwm->state.polarity && pwm->state.enabled) {
+		lpc18xx_pwm_disable(chip, pwm);
+		enabled = false;
+	}
+
+	if (!state->enabled) {
+		if (enabled)
+			lpc18xx_pwm_disable(chip, pwm);
+
+		return 0;
+	}
+
+	err = lpc18xx_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
+	if (err)
+		return err;
+
+	if (!enabled)
+		err = lpc18xx_pwm_enable(chip, pwm, state->polarity);
+
+	return err;
+}
 static const struct pwm_ops lpc18xx_pwm_ops = {
-	.config = lpc18xx_pwm_config,
-	.set_polarity = lpc18xx_pwm_set_polarity,
-	.enable = lpc18xx_pwm_enable,
-	.disable = lpc18xx_pwm_disable,
+	.apply = lpc18xx_pwm_apply,
 	.request = lpc18xx_pwm_request,
 	.free = lpc18xx_pwm_free,
 	.owner = THIS_MODULE,

base-commit: 2bf8ee0faa988b5cec3503ebf2f970a0e84d24ee
-- 
2.35.1


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