537 строки
13 KiB
C
537 строки
13 KiB
C
#ifndef __LINUX_PWM_H
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#define __LINUX_PWM_H
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#include <linux/err.h>
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#include <linux/mutex.h>
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#include <linux/of.h>
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struct seq_file;
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struct pwm_chip;
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/**
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* enum pwm_polarity - polarity of a PWM signal
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* @PWM_POLARITY_NORMAL: a high signal for the duration of the duty-
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* cycle, followed by a low signal for the remainder of the pulse
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* period
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* @PWM_POLARITY_INVERSED: a low signal for the duration of the duty-
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* cycle, followed by a high signal for the remainder of the pulse
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* period
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*/
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enum pwm_polarity {
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PWM_POLARITY_NORMAL,
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PWM_POLARITY_INVERSED,
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};
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/**
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* struct pwm_args - board-dependent PWM arguments
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* @period: reference period
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* @polarity: reference polarity
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*
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* This structure describes board-dependent arguments attached to a PWM
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* device. These arguments are usually retrieved from the PWM lookup table or
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* device tree.
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*
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* Do not confuse this with the PWM state: PWM arguments represent the initial
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* configuration that users want to use on this PWM device rather than the
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* current PWM hardware state.
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*/
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struct pwm_args {
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unsigned int period;
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enum pwm_polarity polarity;
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};
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enum {
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PWMF_REQUESTED = 1 << 0,
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PWMF_EXPORTED = 1 << 1,
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};
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/*
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* struct pwm_state - state of a PWM channel
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* @period: PWM period (in nanoseconds)
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* @duty_cycle: PWM duty cycle (in nanoseconds)
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* @polarity: PWM polarity
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* @enabled: PWM enabled status
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*/
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struct pwm_state {
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unsigned int period;
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unsigned int duty_cycle;
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enum pwm_polarity polarity;
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bool enabled;
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};
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/**
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* struct pwm_device - PWM channel object
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* @label: name of the PWM device
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* @flags: flags associated with the PWM device
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* @hwpwm: per-chip relative index of the PWM device
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* @pwm: global index of the PWM device
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* @chip: PWM chip providing this PWM device
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* @chip_data: chip-private data associated with the PWM device
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* @args: PWM arguments
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* @state: curent PWM channel state
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*/
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struct pwm_device {
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const char *label;
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unsigned long flags;
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unsigned int hwpwm;
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unsigned int pwm;
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struct pwm_chip *chip;
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void *chip_data;
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struct pwm_args args;
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struct pwm_state state;
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};
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/**
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* pwm_get_state() - retrieve the current PWM state
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* @pwm: PWM device
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* @state: state to fill with the current PWM state
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*/
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static inline void pwm_get_state(const struct pwm_device *pwm,
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struct pwm_state *state)
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{
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*state = pwm->state;
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}
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static inline bool pwm_is_enabled(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.enabled;
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}
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static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
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{
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if (pwm)
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pwm->state.period = period;
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}
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static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.period;
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}
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static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
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{
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if (pwm)
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pwm->state.duty_cycle = duty;
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}
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static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.duty_cycle;
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}
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static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.polarity;
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}
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static inline void pwm_get_args(const struct pwm_device *pwm,
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struct pwm_args *args)
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{
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*args = pwm->args;
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}
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/**
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* struct pwm_ops - PWM controller operations
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* @request: optional hook for requesting a PWM
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* @free: optional hook for freeing a PWM
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* @config: configure duty cycles and period length for this PWM
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* @set_polarity: configure the polarity of this PWM
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* @enable: enable PWM output toggling
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* @disable: disable PWM output toggling
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* @apply: atomically apply a new PWM config. The state argument
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* should be adjusted with the real hardware config (if the
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* approximate the period or duty_cycle value, state should
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* reflect it)
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* @get_state: get the current PWM state. This function is only
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* called once per PWM device when the PWM chip is
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* registered.
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* @dbg_show: optional routine to show contents in debugfs
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* @owner: helps prevent removal of modules exporting active PWMs
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*/
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struct pwm_ops {
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int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
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void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
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int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns);
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int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
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enum pwm_polarity polarity);
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int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
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void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
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int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_state *state);
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void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_state *state);
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#ifdef CONFIG_DEBUG_FS
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void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);
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#endif
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struct module *owner;
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};
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/**
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* struct pwm_chip - abstract a PWM controller
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* @dev: device providing the PWMs
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* @list: list node for internal use
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* @ops: callbacks for this PWM controller
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* @base: number of first PWM controlled by this chip
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* @npwm: number of PWMs controlled by this chip
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* @pwms: array of PWM devices allocated by the framework
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* @of_xlate: request a PWM device given a device tree PWM specifier
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* @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
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* @can_sleep: must be true if the .config(), .enable() or .disable()
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* operations may sleep
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*/
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struct pwm_chip {
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struct device *dev;
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struct list_head list;
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const struct pwm_ops *ops;
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int base;
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unsigned int npwm;
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struct pwm_device *pwms;
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struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
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const struct of_phandle_args *args);
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unsigned int of_pwm_n_cells;
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bool can_sleep;
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};
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#if IS_ENABLED(CONFIG_PWM)
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/* PWM user APIs */
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struct pwm_device *pwm_request(int pwm_id, const char *label);
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void pwm_free(struct pwm_device *pwm);
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int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
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int pwm_adjust_config(struct pwm_device *pwm);
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/**
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* pwm_config() - change a PWM device configuration
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* @pwm: PWM device
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* @duty_ns: "on" time (in nanoseconds)
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* @period_ns: duration (in nanoseconds) of one cycle
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*
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* Returns: 0 on success or a negative error code on failure.
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*/
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static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
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int period_ns)
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{
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struct pwm_state state;
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if (!pwm)
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return -EINVAL;
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pwm_get_state(pwm, &state);
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if (state.duty_cycle == duty_ns && state.period == period_ns)
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return 0;
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state.duty_cycle = duty_ns;
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state.period = period_ns;
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return pwm_apply_state(pwm, &state);
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}
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/**
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* pwm_set_polarity() - configure the polarity of a PWM signal
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* @pwm: PWM device
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* @polarity: new polarity of the PWM signal
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*
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* Note that the polarity cannot be configured while the PWM device is
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* enabled.
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*
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* Returns: 0 on success or a negative error code on failure.
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*/
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static inline int pwm_set_polarity(struct pwm_device *pwm,
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enum pwm_polarity polarity)
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{
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struct pwm_state state;
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if (!pwm)
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return -EINVAL;
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pwm_get_state(pwm, &state);
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if (state.polarity == polarity)
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return 0;
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/*
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* Changing the polarity of a running PWM without adjusting the
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* dutycycle/period value is a bit risky (can introduce glitches).
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* Return -EBUSY in this case.
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* Note that this is allowed when using pwm_apply_state() because
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* the user specifies all the parameters.
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*/
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if (state.enabled)
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return -EBUSY;
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state.polarity = polarity;
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return pwm_apply_state(pwm, &state);
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}
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/**
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* pwm_enable() - start a PWM output toggling
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* @pwm: PWM device
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*
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* Returns: 0 on success or a negative error code on failure.
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*/
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static inline int pwm_enable(struct pwm_device *pwm)
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{
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struct pwm_state state;
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if (!pwm)
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return -EINVAL;
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pwm_get_state(pwm, &state);
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if (state.enabled)
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return 0;
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state.enabled = true;
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return pwm_apply_state(pwm, &state);
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}
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/**
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* pwm_disable() - stop a PWM output toggling
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* @pwm: PWM device
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*/
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static inline void pwm_disable(struct pwm_device *pwm)
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{
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struct pwm_state state;
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if (!pwm)
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return;
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pwm_get_state(pwm, &state);
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if (!state.enabled)
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return;
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state.enabled = false;
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pwm_apply_state(pwm, &state);
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}
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/* PWM provider APIs */
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int pwm_set_chip_data(struct pwm_device *pwm, void *data);
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void *pwm_get_chip_data(struct pwm_device *pwm);
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int pwmchip_add_with_polarity(struct pwm_chip *chip,
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enum pwm_polarity polarity);
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int pwmchip_add(struct pwm_chip *chip);
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int pwmchip_remove(struct pwm_chip *chip);
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struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
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unsigned int index,
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const char *label);
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struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
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const struct of_phandle_args *args);
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struct pwm_device *pwm_get(struct device *dev, const char *con_id);
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struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id);
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void pwm_put(struct pwm_device *pwm);
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struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
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struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
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const char *con_id);
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void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
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bool pwm_can_sleep(struct pwm_device *pwm);
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#else
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static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline void pwm_free(struct pwm_device *pwm)
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{
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}
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static inline int pwm_apply_state(struct pwm_device *pwm,
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const struct pwm_state *state)
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{
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return -ENOTSUPP;
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}
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static inline int pwm_adjust_config(struct pwm_device *pwm)
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{
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return -ENOTSUPP;
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}
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static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
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int period_ns)
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{
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return -EINVAL;
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}
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static inline int pwm_set_polarity(struct pwm_device *pwm,
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enum pwm_polarity polarity)
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{
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return -ENOTSUPP;
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}
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static inline int pwm_enable(struct pwm_device *pwm)
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{
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return -EINVAL;
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}
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static inline void pwm_disable(struct pwm_device *pwm)
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{
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}
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static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
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{
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return -EINVAL;
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}
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static inline void *pwm_get_chip_data(struct pwm_device *pwm)
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{
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return NULL;
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}
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static inline int pwmchip_add(struct pwm_chip *chip)
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{
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return -EINVAL;
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}
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static inline int pwmchip_add_inversed(struct pwm_chip *chip)
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{
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return -EINVAL;
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}
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static inline int pwmchip_remove(struct pwm_chip *chip)
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{
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return -EINVAL;
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}
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static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
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unsigned int index,
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const char *label)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline struct pwm_device *pwm_get(struct device *dev,
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const char *consumer)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline struct pwm_device *of_pwm_get(struct device_node *np,
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const char *con_id)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline void pwm_put(struct pwm_device *pwm)
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{
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}
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static inline struct pwm_device *devm_pwm_get(struct device *dev,
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const char *consumer)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
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struct device_node *np,
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const char *con_id)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
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{
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}
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static inline bool pwm_can_sleep(struct pwm_device *pwm)
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{
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return false;
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}
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#endif
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static inline void pwm_apply_args(struct pwm_device *pwm)
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{
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/*
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* PWM users calling pwm_apply_args() expect to have a fresh config
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* where the polarity and period are set according to pwm_args info.
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* The problem is, polarity can only be changed when the PWM is
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* disabled.
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*
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* PWM drivers supporting hardware readout may declare the PWM device
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* as enabled, and prevent polarity setting, which changes from the
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* existing behavior, where all PWM devices are declared as disabled
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* at startup (even if they are actually enabled), thus authorizing
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* polarity setting.
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*
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* Instead of setting ->enabled to false, we call pwm_disable()
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* before pwm_set_polarity() to ensure that everything is configured
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* as expected, and the PWM is really disabled when the user request
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* it.
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*
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* Note that PWM users requiring a smooth handover between the
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* bootloader and the kernel (like critical regulators controlled by
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* PWM devices) will have to switch to the atomic API and avoid calling
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* pwm_apply_args().
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*/
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pwm_disable(pwm);
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pwm_set_polarity(pwm, pwm->args.polarity);
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}
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struct pwm_lookup {
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struct list_head list;
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const char *provider;
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unsigned int index;
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const char *dev_id;
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const char *con_id;
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unsigned int period;
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enum pwm_polarity polarity;
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};
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#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
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{ \
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.provider = _provider, \
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.index = _index, \
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.dev_id = _dev_id, \
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.con_id = _con_id, \
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.period = _period, \
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.polarity = _polarity \
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}
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#if IS_ENABLED(CONFIG_PWM)
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void pwm_add_table(struct pwm_lookup *table, size_t num);
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void pwm_remove_table(struct pwm_lookup *table, size_t num);
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#else
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static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
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{
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}
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static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
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{
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}
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#endif
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#ifdef CONFIG_PWM_SYSFS
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void pwmchip_sysfs_export(struct pwm_chip *chip);
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void pwmchip_sysfs_unexport(struct pwm_chip *chip);
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#else
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static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
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{
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}
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static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
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{
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}
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#endif /* CONFIG_PWM_SYSFS */
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#endif /* __LINUX_PWM_H */
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