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Diffstat (limited to 'include/linux/pwm.h')
| -rw-r--r-- | include/linux/pwm.h | 620 |
1 files changed, 620 insertions, 0 deletions
diff --git a/include/linux/pwm.h b/include/linux/pwm.h new file mode 100644 index 000000000..c0cf66133 --- /dev/null +++ b/include/linux/pwm.h @@ -0,0 +1,620 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_PWM_H +#define __LINUX_PWM_H + +#include <linux/err.h> +#include <linux/mutex.h> +#include <linux/of.h> + +struct pwm_capture; +struct seq_file; + +struct pwm_chip; + +/** + * enum pwm_polarity - polarity of a PWM signal + * @PWM_POLARITY_NORMAL: a high signal for the duration of the duty- + * cycle, followed by a low signal for the remainder of the pulse + * period + * @PWM_POLARITY_INVERSED: a low signal for the duration of the duty- + * cycle, followed by a high signal for the remainder of the pulse + * period + */ +enum pwm_polarity { + PWM_POLARITY_NORMAL, + PWM_POLARITY_INVERSED, +}; + +/** + * struct pwm_args - board-dependent PWM arguments + * @period: reference period + * @polarity: reference polarity + * + * This structure describes board-dependent arguments attached to a PWM + * device. These arguments are usually retrieved from the PWM lookup table or + * device tree. + * + * Do not confuse this with the PWM state: PWM arguments represent the initial + * configuration that users want to use on this PWM device rather than the + * current PWM hardware state. + */ +struct pwm_args { + u64 period; + enum pwm_polarity polarity; +}; + +enum { + PWMF_REQUESTED = 0, + PWMF_EXPORTED = 1, +}; + +/* + * struct pwm_state - state of a PWM channel + * @period: PWM period (in nanoseconds) + * @duty_cycle: PWM duty cycle (in nanoseconds) + * @polarity: PWM polarity + * @enabled: PWM enabled status + */ +struct pwm_state { + u64 period; + u64 duty_cycle; + enum pwm_polarity polarity; + bool enabled; +}; + +/** + * struct pwm_device - PWM channel object + * @label: name of the PWM device + * @flags: flags associated with the PWM device + * @hwpwm: per-chip relative index of the PWM device + * @pwm: global index of the PWM device + * @chip: PWM chip providing this PWM device + * @chip_data: chip-private data associated with the PWM device + * @args: PWM arguments + * @state: last applied state + * @last: last implemented state (for PWM_DEBUG) + */ +struct pwm_device { + const char *label; + unsigned long flags; + unsigned int hwpwm; + unsigned int pwm; + struct pwm_chip *chip; + void *chip_data; + + struct pwm_args args; + struct pwm_state state; + struct pwm_state last; +}; + +/** + * pwm_get_state() - retrieve the current PWM state + * @pwm: PWM device + * @state: state to fill with the current PWM state + */ +static inline void pwm_get_state(const struct pwm_device *pwm, + struct pwm_state *state) +{ + *state = pwm->state; +} + +static inline bool pwm_is_enabled(const struct pwm_device *pwm) +{ + struct pwm_state state; + + pwm_get_state(pwm, &state); + + return state.enabled; +} + +static inline void pwm_set_period(struct pwm_device *pwm, u64 period) +{ + if (pwm) + pwm->state.period = period; +} + +static inline u64 pwm_get_period(const struct pwm_device *pwm) +{ + struct pwm_state state; + + pwm_get_state(pwm, &state); + + return state.period; +} + +static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty) +{ + if (pwm) + pwm->state.duty_cycle = duty; +} + +static inline u64 pwm_get_duty_cycle(const struct pwm_device *pwm) +{ + struct pwm_state state; + + pwm_get_state(pwm, &state); + + return state.duty_cycle; +} + +static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm) +{ + struct pwm_state state; + + pwm_get_state(pwm, &state); + + return state.polarity; +} + +static inline void pwm_get_args(const struct pwm_device *pwm, + struct pwm_args *args) +{ + *args = pwm->args; +} + +/** + * pwm_init_state() - prepare a new state to be applied with pwm_apply_state() + * @pwm: PWM device + * @state: state to fill with the prepared PWM state + * + * This functions prepares a state that can later be tweaked and applied + * to the PWM device with pwm_apply_state(). This is a convenient function + * that first retrieves the current PWM state and the replaces the period + * and polarity fields with the reference values defined in pwm->args. + * Once the function returns, you can adjust the ->enabled and ->duty_cycle + * fields according to your needs before calling pwm_apply_state(). + * + * ->duty_cycle is initially set to zero to avoid cases where the current + * ->duty_cycle value exceed the pwm_args->period one, which would trigger + * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle + * first. + */ +static inline void pwm_init_state(const struct pwm_device *pwm, + struct pwm_state *state) +{ + struct pwm_args args; + + /* First get the current state. */ + pwm_get_state(pwm, state); + + /* Then fill it with the reference config */ + pwm_get_args(pwm, &args); + + state->period = args.period; + state->polarity = args.polarity; + state->duty_cycle = 0; +} + +/** + * pwm_get_relative_duty_cycle() - Get a relative duty cycle value + * @state: PWM state to extract the duty cycle from + * @scale: target scale of the relative duty cycle + * + * This functions converts the absolute duty cycle stored in @state (expressed + * in nanosecond) into a value relative to the period. + * + * For example if you want to get the duty_cycle expressed in percent, call: + * + * pwm_get_state(pwm, &state); + * duty = pwm_get_relative_duty_cycle(&state, 100); + */ +static inline unsigned int +pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale) +{ + if (!state->period) + return 0; + + return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale, + state->period); +} + +/** + * pwm_set_relative_duty_cycle() - Set a relative duty cycle value + * @state: PWM state to fill + * @duty_cycle: relative duty cycle value + * @scale: scale in which @duty_cycle is expressed + * + * This functions converts a relative into an absolute duty cycle (expressed + * in nanoseconds), and puts the result in state->duty_cycle. + * + * For example if you want to configure a 50% duty cycle, call: + * + * pwm_init_state(pwm, &state); + * pwm_set_relative_duty_cycle(&state, 50, 100); + * pwm_apply_state(pwm, &state); + * + * This functions returns -EINVAL if @duty_cycle and/or @scale are + * inconsistent (@scale == 0 or @duty_cycle > @scale). + */ +static inline int +pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle, + unsigned int scale) +{ + if (!scale || duty_cycle > scale) + return -EINVAL; + + state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle * + state->period, + scale); + + return 0; +} + +/** + * struct pwm_ops - PWM controller operations + * @request: optional hook for requesting a PWM + * @free: optional hook for freeing a PWM + * @capture: capture and report PWM signal + * @apply: atomically apply a new PWM config + * @get_state: get the current PWM state. This function is only + * called once per PWM device when the PWM chip is + * registered. + * @owner: helps prevent removal of modules exporting active PWMs + * @config: configure duty cycles and period length for this PWM + * @set_polarity: configure the polarity of this PWM + * @enable: enable PWM output toggling + * @disable: disable PWM output toggling + */ +struct pwm_ops { + int (*request)(struct pwm_chip *chip, struct pwm_device *pwm); + void (*free)(struct pwm_chip *chip, struct pwm_device *pwm); + int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_capture *result, unsigned long timeout); + int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state); + void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state); + struct module *owner; + + /* Only used by legacy drivers */ + int (*config)(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns); + int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm, + enum pwm_polarity polarity); + int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm); + void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm); +}; + +/** + * struct pwm_chip - abstract a PWM controller + * @dev: device providing the PWMs + * @ops: callbacks for this PWM controller + * @base: number of first PWM controlled by this chip + * @npwm: number of PWMs controlled by this chip + * @of_xlate: request a PWM device given a device tree PWM specifier + * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier + * @list: list node for internal use + * @pwms: array of PWM devices allocated by the framework + */ +struct pwm_chip { + struct device *dev; + const struct pwm_ops *ops; + int base; + unsigned int npwm; + + struct pwm_device * (*of_xlate)(struct pwm_chip *pc, + const struct of_phandle_args *args); + unsigned int of_pwm_n_cells; + + /* only used internally by the PWM framework */ + struct list_head list; + struct pwm_device *pwms; +}; + +/** + * struct pwm_capture - PWM capture data + * @period: period of the PWM signal (in nanoseconds) + * @duty_cycle: duty cycle of the PWM signal (in nanoseconds) + */ +struct pwm_capture { + unsigned int period; + unsigned int duty_cycle; +}; + +#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, const 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; + + 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; + + state.duty_cycle = duty_ns; + state.period = period_ns; + 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_capture(struct pwm_device *pwm, struct pwm_capture *result, + unsigned long timeout); +int pwm_set_chip_data(struct pwm_device *pwm, void *data); +void *pwm_get_chip_data(struct pwm_device *pwm); + +int pwmchip_add_with_polarity(struct pwm_chip *chip, + enum pwm_polarity polarity); +int pwmchip_add(struct pwm_chip *chip); +int pwmchip_remove(struct pwm_chip *chip); +struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip, + unsigned int index, + const char *label); + +struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc, + const struct of_phandle_args *args); + +struct pwm_device *pwm_get(struct device *dev, const char *con_id); +struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np, + const char *con_id); +void pwm_put(struct pwm_device *pwm); + +struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id); +struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np, + const char *con_id); +struct pwm_device *devm_fwnode_pwm_get(struct device *dev, + struct fwnode_handle *fwnode, + const char *con_id); +void devm_pwm_put(struct device *dev, 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_capture(struct pwm_device *pwm, + struct pwm_capture *result, + unsigned long timeout) +{ + return -EINVAL; +} + +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; +} + +static inline void *pwm_get_chip_data(struct pwm_device *pwm) +{ + return NULL; +} + +static inline int pwmchip_add(struct pwm_chip *chip) +{ + return -EINVAL; +} + +static inline int pwmchip_add_inversed(struct pwm_chip *chip) +{ + return -EINVAL; +} + +static inline int pwmchip_remove(struct pwm_chip *chip) +{ + return -EINVAL; +} + +static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip, + unsigned int index, + const char *label) +{ + return ERR_PTR(-ENODEV); +} + +static inline struct pwm_device *pwm_get(struct device *dev, + const char *consumer) +{ + return ERR_PTR(-ENODEV); +} + +static inline struct pwm_device *of_pwm_get(struct device *dev, + struct device_node *np, + const char *con_id) +{ + return ERR_PTR(-ENODEV); +} + +static inline void pwm_put(struct pwm_device *pwm) +{ +} + +static inline struct pwm_device *devm_pwm_get(struct device *dev, + const char *consumer) +{ + return ERR_PTR(-ENODEV); +} + +static inline struct pwm_device *devm_of_pwm_get(struct device *dev, + struct device_node *np, + const char *con_id) +{ + return ERR_PTR(-ENODEV); +} + +static inline struct pwm_device * +devm_fwnode_pwm_get(struct device *dev, struct fwnode_handle *fwnode, + const char *con_id) +{ + return ERR_PTR(-ENODEV); +} + +static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm) +{ +} +#endif + +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. + * 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. + * + * 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(). + */ + + state.enabled = false; + state.polarity = pwm->args.polarity; + state.period = pwm->args.period; + + pwm_apply_state(pwm, &state); +} + +struct pwm_lookup { + struct list_head list; + const char *provider; + unsigned int index; + const char *dev_id; + const char *con_id; + unsigned int period; + enum pwm_polarity polarity; + const char *module; /* optional, may be NULL */ +}; + +#define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, \ + _period, _polarity, _module) \ + { \ + .provider = _provider, \ + .index = _index, \ + .dev_id = _dev_id, \ + .con_id = _con_id, \ + .period = _period, \ + .polarity = _polarity, \ + .module = _module, \ + } + +#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \ + PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \ + _polarity, NULL) + +#if IS_ENABLED(CONFIG_PWM) +void pwm_add_table(struct pwm_lookup *table, size_t num); +void pwm_remove_table(struct pwm_lookup *table, size_t num); +#else +static inline void pwm_add_table(struct pwm_lookup *table, size_t num) +{ +} + +static inline void pwm_remove_table(struct pwm_lookup *table, size_t num) +{ +} +#endif + +#ifdef CONFIG_PWM_SYSFS +void pwmchip_sysfs_export(struct pwm_chip *chip); +void pwmchip_sysfs_unexport(struct pwm_chip *chip); +#else +static inline void pwmchip_sysfs_export(struct pwm_chip *chip) +{ +} + +static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip) +{ +} +#endif /* CONFIG_PWM_SYSFS */ + +#endif /* __LINUX_PWM_H */ |