pwm: cros-ec: Put per-channel data into driver data

Instead of an allocation of a single u16 per channel, allocate them all in
a single chunk which greatly reduces memory fragmentation and also the
overhead to track the allocated memory. Also put the channel data in
driver data where it's cheaper to determine the address (no function call
involved, just a trivial pointer addition).

This also allows to get rid of the request and free callbacks.

The only cost is that the channel data is allocated early, and even for
unused channels.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20230705080650.2353391-8-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-cros-ec.c

@@ -22,12 +22,14 @@
  * @ec: Pointer to EC device
  * @chip: PWM controller chip
  * @use_pwm_type: Use PWM types instead of generic channels
+ * @channel: array with per-channel data
  */
 struct cros_ec_pwm_device {
 	struct device *dev;
 	struct cros_ec_device *ec;
 	struct pwm_chip chip;
 	bool use_pwm_type;
+	struct cros_ec_pwm *channel;
 };
 
 /**
@@ -43,26 +45,6 @@ static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *chi
 	return container_of(chip, struct cros_ec_pwm_device, chip);
 }
 
-static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct cros_ec_pwm *channel;
-
-	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
-	if (!channel)
-		return -ENOMEM;
-
-	pwm_set_chip_data(pwm, channel);
-
-	return 0;
-}
-
-static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
-
-	kfree(channel);
-}
-
 static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type)
 {
 	switch (dt_index) {
@@ -158,7 +140,7 @@ static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			     const struct pwm_state *state)
 {
 	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
-	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
+	struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm];
 	u16 duty_cycle;
 	int ret;
 
@@ -188,7 +170,7 @@ static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 				 struct pwm_state *state)
 {
 	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
-	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
+	struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm];
 	int ret;
 
 	ret = cros_ec_pwm_get_duty(ec_pwm, pwm->hwpwm);
@@ -237,8 +219,6 @@ cros_ec_pwm_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
 }
 
 static const struct pwm_ops cros_ec_pwm_ops = {
-	.request = cros_ec_pwm_request,
-	.free = cros_ec_pwm_free,
 	.get_state	= cros_ec_pwm_get_state,
 	.apply		= cros_ec_pwm_apply,
 };
@@ -316,6 +296,11 @@ static int cros_ec_pwm_probe(struct platform_device *pdev)
 		chip->npwm = ret;
 	}
 
+	ec_pwm->channel = devm_kcalloc(dev, chip->npwm, sizeof(*ec_pwm->channel),
+					GFP_KERNEL);
+	if (!ec_pwm->channel)
+		return -ENOMEM;
+
 	dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
 
 	ret = pwmchip_add(chip);