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: 6c5126c6406d ("pwm: Provide new consumer API functions for waveforms") Cc: stable@vger.kernel.org Signed-off-by: Uwe Kleine-König u.kleine-koenig@baylibre.com --- Hello,

assuming nobody spots a problem I will send this patch to Linus next week for inclusion in -rc1.

Best regards Uwe

drivers/pwm/core.c | 13 +++++++++++-- include/linux/pwm.h | 17 +++++++++++++++++ 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 9c733877e98e..1a36ee3cab91 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -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;

diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 78827f312407..b8d78009e779 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -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;

base-commit: e8c59791ebb60790c74b2c3ab520f04a8a57219a prerequisite-patch-id: f5f481d393ddd1fd20a685c86cd4e93dd40d26c7