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pwm: Ensure callbacks exist before calling them

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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: 6c5126c640 ("pwm: Provide new consumer API functions for waveforms")
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/20250123172709.391349-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
This commit is contained in:
Uwe Kleine-König 2025-01-23 18:27:07 +01:00 committed by Uwe Kleine-König
parent 752b6e3af3
commit da6b353786
2 changed files with 28 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/pwm/core.c
View File

@ -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;

17
include/linux/pwm.h
View File

@ -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;