From ef2bf4997f7da6efa8540d9cf726c44bf2b863af Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Fri, 27 May 2016 09:45:49 -0700 Subject: [PATCH 1/4] pwm: Improve args checking in pwm_apply_state() It seems like in the process of refactoring pwm_config() to utilize the newly-introduced pwm_apply_state() API, some args/bounds checking was dropped. In particular, I noted that we are now allowing invalid period selections, e.g.: # echo 1 > /sys/class/pwm/pwmchip0/export # cat /sys/class/pwm/pwmchip0/pwm1/period 100 # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle [... driver may or may not reject the value, or trigger some logic bug ...] It's better to see: # echo 1 > /sys/class/pwm/pwmchip0/export # cat /sys/class/pwm/pwmchip0/pwm1/period 100 # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle -bash: echo: write error: Invalid argument This patch reintroduces some bounds checks in both pwm_config() (for its signed parameters; we don't want to convert negative values into large unsigned values) and in pwm_apply_state() (which fix the above described behavior, as well as other potential API misuses). Fixes: 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates") Signed-off-by: Brian Norris Acked-by: Boris Brezillon Signed-off-by: Thierry Reding --- drivers/pwm/core.c | 3 ++- include/linux/pwm.h | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index dba3843c53b8..ed337a8c34ab 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -457,7 +457,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) { int err; - if (!pwm) + if (!pwm || !state || !state->period || + state->duty_cycle > state->period) return -EINVAL; if (!memcmp(state, &pwm->state, sizeof(*state))) diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 17018f3c066e..908b67c847cd 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -235,6 +235,9 @@ static inline int pwm_config(struct pwm_device *pwm, int duty_ns, if (!pwm) return -EINVAL; + if (duty_ns < 0 || period_ns < 0) + return -EINVAL; + pwm_get_state(pwm, &state); if (state.duty_cycle == duty_ns && state.period == period_ns) return 0; From fe5aa34d6eb9c4d34071845f70f3714b41c8a77d Mon Sep 17 00:00:00 2001 From: Ryo Kodama Date: Wed, 8 Jun 2016 10:58:23 +0900 Subject: [PATCH 2/4] pwm: sysfs: Get return value from pwm_apply_state() This patch adds to check the return value from pwm_apply_state() used in enable_store(). The error of enable_store() doesn't work if the return value doesn't received. Signed-off-by: Ryo Kodama Signed-off-by: Yoshihiro Shimoda Fixes: 39100ceea79f ("pwm: Switch to the atomic API") Signed-off-by: Thierry Reding --- drivers/pwm/sysfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c index d98599249a05..01695d48dd54 100644 --- a/drivers/pwm/sysfs.c +++ b/drivers/pwm/sysfs.c @@ -152,7 +152,7 @@ static ssize_t enable_store(struct device *child, goto unlock; } - pwm_apply_state(pwm, &state); + ret = pwm_apply_state(pwm, &state); unlock: mutex_unlock(&export->lock); From cc51846ba81ca179a3be20f6313e3b72531888c1 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 17 May 2016 11:12:32 +0200 Subject: [PATCH 3/4] pwm: atmel-hlcdc: Fix default PWM polarity The PWM device exposed by the HLCDC IP is configured with an inverted polarity by default. Registering the PWM chip with the normal polarity was not a problem before commit 42e8992c58d4 ("pwm: Add core infrastructure to allow atomic updates") because the ->set_polarity() hook was called no matter the current polarity state, but this is no longer the case. Signed-off-by: Boris Brezillon Signed-off-by: Thierry Reding --- drivers/pwm/pwm-atmel-hlcdc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-atmel-hlcdc.c b/drivers/pwm/pwm-atmel-hlcdc.c index f994c7eaf41c..14fc011faa32 100644 --- a/drivers/pwm/pwm-atmel-hlcdc.c +++ b/drivers/pwm/pwm-atmel-hlcdc.c @@ -272,7 +272,7 @@ static int atmel_hlcdc_pwm_probe(struct platform_device *pdev) chip->chip.of_pwm_n_cells = 3; chip->chip.can_sleep = 1; - ret = pwmchip_add(&chip->chip); + ret = pwmchip_add_with_polarity(&chip->chip, PWM_POLARITY_INVERSED); if (ret) { clk_disable_unprepare(hlcdc->periph_clk); return ret; From 33cdcee04be3b4482be97393167e7561b2584e1e Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Wed, 22 Jun 2016 09:25:14 +0200 Subject: [PATCH 4/4] pwm: Fix pwm_apply_args() Commit 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates"), implemented pwm_disable() as a wrapper around pwm_apply_state(), and then, commit ef2bf4997f7d ("pwm: Improve args checking in pwm_apply_state()") added missing checks on the ->period value in pwm_apply_state() to ensure we were not passing inappropriate values to the ->config() or ->apply() methods. The conjunction of these 2 commits led to a case where pwm_disable() was no longer succeeding, thus preventing the polarity setting done in pwm_apply_args(). Set a valid period in pwm_apply_args() to ensure polarity setting won't be rejected. Signed-off-by: Boris Brezillon Reported-by: Geert Uytterhoeven Suggested-by: Brian Norris Fixes: 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates") Tested-by: Geert Uytterhoeven Reviewed-by: Brian Norris Signed-off-by: Thierry Reding --- include/linux/pwm.h | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 908b67c847cd..c038ae36b10e 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -464,6 +464,8 @@ static inline bool pwm_can_sleep(struct pwm_device *pwm) static inline void pwm_apply_args(struct pwm_device *pwm) { + struct pwm_state state = { }; + /* * PWM users calling pwm_apply_args() expect to have a fresh config * where the polarity and period are set according to pwm_args info. @@ -476,18 +478,20 @@ static inline void pwm_apply_args(struct pwm_device *pwm) * at startup (even if they are actually enabled), thus authorizing * polarity setting. * - * Instead of setting ->enabled to false, we call pwm_disable() - * before pwm_set_polarity() to ensure that everything is configured - * as expected, and the PWM is really disabled when the user request - * it. + * To fulfill this requirement, we apply a new state which disables + * the PWM device and set the reference period and polarity config. * * Note that PWM users requiring a smooth handover between the * bootloader and the kernel (like critical regulators controlled by * PWM devices) will have to switch to the atomic API and avoid calling * pwm_apply_args(). */ - pwm_disable(pwm); - pwm_set_polarity(pwm, pwm->args.polarity); + + state.enabled = false; + state.polarity = pwm->args.polarity; + state.period = pwm->args.period; + + pwm_apply_state(pwm, &state); } struct pwm_lookup {