Commit da6b3537 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Uwe Kleine-König
Browse files

pwm: Ensure callbacks exist before calling them 



If one of the waveform functions is called for a chip that only supports
.apply(), we want that an error code is returned and not a NULL pointer
exception.

Fixes: 6c5126c6 ("pwm: Provide new consumer API functions for waveforms")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: default avatarTrevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/20250123172709.391349-2-u.kleine-koenig@baylibre.com


Signed-off-by: default avatarUwe Kleine-König <ukleinek@kernel.org>
parent 752b6e3a

drivers/pwm/core.c

+11 −2
Original line number Diff line number Diff line
@@ -242,6 +242,9 @@ int pwm_round_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform * 


	BUG_ON(WFHWSIZE < ops->sizeof_wfhw);



	if (!pwmchip_supports_waveform(chip))

		return -EOPNOTSUPP;



	if (!pwm_wf_valid(wf))

		return -EINVAL;
@@ -294,6 +297,9 @@ int pwm_get_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *wf 


	BUG_ON(WFHWSIZE < ops->sizeof_wfhw);



	if (!pwmchip_supports_waveform(chip) || !ops->read_waveform)

		return -EOPNOTSUPP;



	guard(pwmchip)(chip);



	if (!chip->operational)
@@ -320,6 +326,9 @@ static int __pwm_set_waveform(struct pwm_device *pwm, 


	BUG_ON(WFHWSIZE < ops->sizeof_wfhw);



	if (!pwmchip_supports_waveform(chip))

		return -EOPNOTSUPP;



	if (!pwm_wf_valid(wf))

		return -EINVAL;
@@ -592,7 +601,7 @@ static int __pwm_apply(struct pwm_device *pwm, const struct pwm_state *state) 
	    state->usage_power == pwm->state.usage_power)

		return 0;



	if (ops->write_waveform) {

	if (pwmchip_supports_waveform(chip)) {

		struct pwm_waveform wf;

		char wfhw[WFHWSIZE];
@@ -746,7 +755,7 @@ int pwm_get_state_hw(struct pwm_device *pwm, struct pwm_state *state) 
	if (!chip->operational)

		return -ENODEV;



	if (ops->read_waveform) {

	if (pwmchip_supports_waveform(chip) && ops->read_waveform) {

		char wfhw[WFHWSIZE];

		struct pwm_waveform wf;

include/linux/pwm.h

+17 −0
Original line number Diff line number Diff line
@@ -347,6 +347,23 @@ struct pwm_chip { 
	struct pwm_device pwms[] __counted_by(npwm);

};



/**

 * pwmchip_supports_waveform() - checks if the given chip supports waveform callbacks

 * @chip: The pwm_chip to test

 *

 * Returns true iff the pwm chip support the waveform functions like

 * pwm_set_waveform_might_sleep() and pwm_round_waveform_might_sleep()

 */

static inline bool pwmchip_supports_waveform(struct pwm_chip *chip)

{

	/*

	 * only check for .write_waveform(). If that is available,

	 * .round_waveform_tohw() and .round_waveform_fromhw() asserted to be

	 * available, too, in pwmchip_add().

	 */

	return chip->ops->write_waveform != NULL;

}



static inline struct device *pwmchip_parent(const struct pwm_chip *chip)

{

	return chip->dev.parent;