Current File : //usr/src/linux-headers-5.15.0-125-generic/include/linux/pwm.h
/* 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
* @usage_power: If set, the PWM driver is only required to maintain the power
* output but has more freedom regarding signal form.
* If supported, the signal can be optimized, for example to
* improve EMI by phase shifting individual channels.
*/
struct pwm_state {
u64 period;
u64 duty_cycle;
enum pwm_polarity polarity;
bool enabled;
bool usage_power;
};
/**
* 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
*
* The returned PWM state represents the state that was applied by a previous call to
* pwm_apply_state(). Drivers may have to slightly tweak that state before programming it to
* hardware. If pwm_apply_state() was never called, this returns either the current hardware
* state (if supported) or the default settings.
*/
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;
state->usage_power = false;
}
/**
* 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(struct pwm_chip *chip);
void pwmchip_remove(struct pwm_chip *chip);
int devm_pwmchip_add(struct device *dev, 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);
#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_remove(struct pwm_chip *chip)
{
return -EINVAL;
}
static inline int devm_pwmchip_add(struct device *dev, 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);
}
#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;
state.usage_power = false;
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 */
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