diff options
Diffstat (limited to 'include/linux/pwm.h')
| -rw-r--r-- | include/linux/pwm.h | 269 |
1 files changed, 184 insertions, 85 deletions
diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 33f8decd9f38..17018f3c066e 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -5,59 +5,7 @@ #include <linux/mutex.h> #include <linux/of.h> -struct pwm_device; struct seq_file; - -#if IS_ENABLED(CONFIG_PWM) -/* - * pwm_request - request a PWM device - */ -struct pwm_device *pwm_request(int pwm_id, const char *label); - -/* - * pwm_free - free a PWM device - */ -void pwm_free(struct pwm_device *pwm); - -/* - * pwm_config - change a PWM device configuration - */ -int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns); - -/* - * pwm_enable - start a PWM output toggling - */ -int pwm_enable(struct pwm_device *pwm); - -/* - * pwm_disable - stop a PWM output toggling - */ -void pwm_disable(struct pwm_device *pwm); -#else -static inline struct pwm_device *pwm_request(int pwm_id, const char *label) -{ - return ERR_PTR(-ENODEV); -} - -static inline void pwm_free(struct pwm_device *pwm) -{ -} - -static inline int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) -{ - return -EINVAL; -} - -static inline int pwm_enable(struct pwm_device *pwm) -{ - return -EINVAL; -} - -static inline void pwm_disable(struct pwm_device *pwm) -{ -} -#endif - struct pwm_chip; /** @@ -184,11 +132,6 @@ static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm) return state.duty_cycle; } -/* - * pwm_set_polarity - configure the polarity of a PWM signal - */ -int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity); - static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm) { struct pwm_state state; @@ -204,34 +147,6 @@ static inline void pwm_get_args(const struct pwm_device *pwm, *args = pwm->args; } -static inline void pwm_apply_args(struct pwm_device *pwm) -{ - /* - * PWM users calling pwm_apply_args() expect to have a fresh config - * where the polarity and period are set according to pwm_args info. - * The problem is, polarity can only be changed when the PWM is - * disabled. - * - * PWM drivers supporting hardware readout may declare the PWM device - * as enabled, and prevent polarity setting, which changes from the - * existing behavior, where all PWM devices are declared as disabled - * 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. - * - * 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); -} - /** * struct pwm_ops - PWM controller operations * @request: optional hook for requesting a PWM @@ -240,6 +155,10 @@ static inline void pwm_apply_args(struct pwm_device *pwm) * @set_polarity: configure the polarity of this PWM * @enable: enable PWM output toggling * @disable: disable PWM output toggling + * @apply: atomically apply a new PWM config. The state argument + * should be adjusted with the real hardware config (if the + * approximate the period or duty_cycle value, state should + * reflect it) * @get_state: get the current PWM state. This function is only * called once per PWM device when the PWM chip is * registered. @@ -255,6 +174,8 @@ struct pwm_ops { enum pwm_polarity polarity); int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm); void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm); + int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state); void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state); #ifdef CONFIG_DEBUG_FS @@ -292,6 +213,115 @@ struct pwm_chip { }; #if IS_ENABLED(CONFIG_PWM) +/* PWM user APIs */ +struct pwm_device *pwm_request(int pwm_id, const char *label); +void pwm_free(struct pwm_device *pwm); +int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state); +int pwm_adjust_config(struct pwm_device *pwm); + +/** + * pwm_config() - change a PWM device configuration + * @pwm: PWM device + * @duty_ns: "on" time (in nanoseconds) + * @period_ns: duration (in nanoseconds) of one cycle + * + * Returns: 0 on success or a negative error code on failure. + */ +static inline int pwm_config(struct pwm_device *pwm, int duty_ns, + int period_ns) +{ + struct pwm_state state; + + if (!pwm) + return -EINVAL; + + pwm_get_state(pwm, &state); + if (state.duty_cycle == duty_ns && state.period == period_ns) + return 0; + + state.duty_cycle = duty_ns; + state.period = period_ns; + return pwm_apply_state(pwm, &state); +} + +/** + * pwm_set_polarity() - configure the polarity of a PWM signal + * @pwm: PWM device + * @polarity: new polarity of the PWM signal + * + * Note that the polarity cannot be configured while the PWM device is + * enabled. + * + * Returns: 0 on success or a negative error code on failure. + */ +static inline int pwm_set_polarity(struct pwm_device *pwm, + enum pwm_polarity polarity) +{ + struct pwm_state state; + + if (!pwm) + return -EINVAL; + + pwm_get_state(pwm, &state); + if (state.polarity == polarity) + return 0; + + /* + * Changing the polarity of a running PWM without adjusting the + * dutycycle/period value is a bit risky (can introduce glitches). + * Return -EBUSY in this case. + * Note that this is allowed when using pwm_apply_state() because + * the user specifies all the parameters. + */ + if (state.enabled) + return -EBUSY; + + state.polarity = polarity; + return pwm_apply_state(pwm, &state); +} + +/** + * pwm_enable() - start a PWM output toggling + * @pwm: PWM device + * + * Returns: 0 on success or a negative error code on failure. + */ +static inline int pwm_enable(struct pwm_device *pwm) +{ + struct pwm_state state; + + if (!pwm) + return -EINVAL; + + pwm_get_state(pwm, &state); + if (state.enabled) + return 0; + + state.enabled = true; + return pwm_apply_state(pwm, &state); +} + +/** + * pwm_disable() - stop a PWM output toggling + * @pwm: PWM device + */ +static inline void pwm_disable(struct pwm_device *pwm) +{ + struct pwm_state state; + + if (!pwm) + return; + + pwm_get_state(pwm, &state); + if (!state.enabled) + return; + + state.enabled = false; + pwm_apply_state(pwm, &state); +} + + +/* PWM provider APIs */ int pwm_set_chip_data(struct pwm_device *pwm, void *data); void *pwm_get_chip_data(struct pwm_device *pwm); @@ -317,6 +347,47 @@ void devm_pwm_put(struct device *dev, struct pwm_device *pwm); bool pwm_can_sleep(struct pwm_device *pwm); #else +static inline struct pwm_device *pwm_request(int pwm_id, const char *label) +{ + return ERR_PTR(-ENODEV); +} + +static inline void pwm_free(struct pwm_device *pwm) +{ +} + +static inline int pwm_apply_state(struct pwm_device *pwm, + const struct pwm_state *state) +{ + return -ENOTSUPP; +} + +static inline int pwm_adjust_config(struct pwm_device *pwm) +{ + return -ENOTSUPP; +} + +static inline int pwm_config(struct pwm_device *pwm, int duty_ns, + int period_ns) +{ + return -EINVAL; +} + +static inline int pwm_set_polarity(struct pwm_device *pwm, + enum pwm_polarity polarity) +{ + return -ENOTSUPP; +} + +static inline int pwm_enable(struct pwm_device *pwm) +{ + return -EINVAL; +} + +static inline void pwm_disable(struct pwm_device *pwm) +{ +} + static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data) { return -EINVAL; @@ -388,6 +459,34 @@ static inline bool pwm_can_sleep(struct pwm_device *pwm) } #endif +static inline void pwm_apply_args(struct pwm_device *pwm) +{ + /* + * PWM users calling pwm_apply_args() expect to have a fresh config + * where the polarity and period are set according to pwm_args info. + * The problem is, polarity can only be changed when the PWM is + * disabled. + * + * PWM drivers supporting hardware readout may declare the PWM device + * as enabled, and prevent polarity setting, which changes from the + * existing behavior, where all PWM devices are declared as disabled + * 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. + * + * 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); +} + struct pwm_lookup { struct list_head list; const char *provider; |