1 /* SPDX-License-Identifier: GPL-2.0 */
6 #include <linux/mutex.h>
15 * enum pwm_polarity - polarity of a PWM signal
16 * @PWM_POLARITY_NORMAL: a high signal for the duration of the duty-
17 * cycle, followed by a low signal for the remainder of the pulse
19 * @PWM_POLARITY_INVERSED: a low signal for the duration of the duty-
20 * cycle, followed by a high signal for the remainder of the pulse
25 PWM_POLARITY_INVERSED,
29 * struct pwm_args - board-dependent PWM arguments
30 * @period: reference period
31 * @polarity: reference polarity
33 * This structure describes board-dependent arguments attached to a PWM
34 * device. These arguments are usually retrieved from the PWM lookup table or
37 * Do not confuse this with the PWM state: PWM arguments represent the initial
38 * configuration that users want to use on this PWM device rather than the
39 * current PWM hardware state.
43 enum pwm_polarity polarity;
47 PWMF_REQUESTED = 1 << 0,
48 PWMF_EXPORTED = 1 << 1,
52 * struct pwm_state - state of a PWM channel
53 * @period: PWM period (in nanoseconds)
54 * @duty_cycle: PWM duty cycle (in nanoseconds)
55 * @polarity: PWM polarity
56 * @enabled: PWM enabled status
57 * @usage_power: If set, the PWM driver is only required to maintain the power
58 * output but has more freedom regarding signal form.
59 * If supported, the signal can be optimized, for example to
60 * improve EMI by phase shifting individual channels.
65 enum pwm_polarity polarity;
71 * struct pwm_device - PWM channel object
72 * @label: name of the PWM device
73 * @flags: flags associated with the PWM device
74 * @hwpwm: per-chip relative index of the PWM device
75 * @pwm: global index of the PWM device
76 * @chip: PWM chip providing this PWM device
77 * @chip_data: chip-private data associated with the PWM device
78 * @args: PWM arguments
79 * @state: last applied state
80 * @last: last implemented state (for PWM_DEBUG)
87 struct pwm_chip *chip;
91 struct pwm_state state;
92 struct pwm_state last;
96 * pwm_get_state() - retrieve the current PWM state
98 * @state: state to fill with the current PWM state
100 * The returned PWM state represents the state that was applied by a previous call to
101 * pwm_apply_state(). Drivers may have to slightly tweak that state before programming it to
102 * hardware. If pwm_apply_state() was never called, this returns either the current hardware
103 * state (if supported) or the default settings.
105 static inline void pwm_get_state(const struct pwm_device *pwm,
106 struct pwm_state *state)
111 static inline bool pwm_is_enabled(const struct pwm_device *pwm)
113 struct pwm_state state;
115 pwm_get_state(pwm, &state);
117 return state.enabled;
120 static inline void pwm_set_period(struct pwm_device *pwm, u64 period)
123 pwm->state.period = period;
126 static inline u64 pwm_get_period(const struct pwm_device *pwm)
128 struct pwm_state state;
130 pwm_get_state(pwm, &state);
135 static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
138 pwm->state.duty_cycle = duty;
141 static inline u64 pwm_get_duty_cycle(const struct pwm_device *pwm)
143 struct pwm_state state;
145 pwm_get_state(pwm, &state);
147 return state.duty_cycle;
150 static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
152 struct pwm_state state;
154 pwm_get_state(pwm, &state);
156 return state.polarity;
159 static inline void pwm_get_args(const struct pwm_device *pwm,
160 struct pwm_args *args)
166 * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
168 * @state: state to fill with the prepared PWM state
170 * This functions prepares a state that can later be tweaked and applied
171 * to the PWM device with pwm_apply_state(). This is a convenient function
172 * that first retrieves the current PWM state and the replaces the period
173 * and polarity fields with the reference values defined in pwm->args.
174 * Once the function returns, you can adjust the ->enabled and ->duty_cycle
175 * fields according to your needs before calling pwm_apply_state().
177 * ->duty_cycle is initially set to zero to avoid cases where the current
178 * ->duty_cycle value exceed the pwm_args->period one, which would trigger
179 * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
182 static inline void pwm_init_state(const struct pwm_device *pwm,
183 struct pwm_state *state)
185 struct pwm_args args;
187 /* First get the current state. */
188 pwm_get_state(pwm, state);
190 /* Then fill it with the reference config */
191 pwm_get_args(pwm, &args);
193 state->period = args.period;
194 state->polarity = args.polarity;
195 state->duty_cycle = 0;
196 state->usage_power = false;
200 * pwm_get_relative_duty_cycle() - Get a relative duty cycle value
201 * @state: PWM state to extract the duty cycle from
202 * @scale: target scale of the relative duty cycle
204 * This functions converts the absolute duty cycle stored in @state (expressed
205 * in nanosecond) into a value relative to the period.
207 * For example if you want to get the duty_cycle expressed in percent, call:
209 * pwm_get_state(pwm, &state);
210 * duty = pwm_get_relative_duty_cycle(&state, 100);
212 static inline unsigned int
213 pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
218 return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
223 * pwm_set_relative_duty_cycle() - Set a relative duty cycle value
224 * @state: PWM state to fill
225 * @duty_cycle: relative duty cycle value
226 * @scale: scale in which @duty_cycle is expressed
228 * This functions converts a relative into an absolute duty cycle (expressed
229 * in nanoseconds), and puts the result in state->duty_cycle.
231 * For example if you want to configure a 50% duty cycle, call:
233 * pwm_init_state(pwm, &state);
234 * pwm_set_relative_duty_cycle(&state, 50, 100);
235 * pwm_apply_state(pwm, &state);
237 * This functions returns -EINVAL if @duty_cycle and/or @scale are
238 * inconsistent (@scale == 0 or @duty_cycle > @scale).
241 pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
244 if (!scale || duty_cycle > scale)
247 state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
255 * struct pwm_ops - PWM controller operations
256 * @request: optional hook for requesting a PWM
257 * @free: optional hook for freeing a PWM
258 * @capture: capture and report PWM signal
259 * @apply: atomically apply a new PWM config
260 * @get_state: get the current PWM state. This function is only
261 * called once per PWM device when the PWM chip is
263 * @owner: helps prevent removal of modules exporting active PWMs
264 * @config: configure duty cycles and period length for this PWM
265 * @set_polarity: configure the polarity of this PWM
266 * @enable: enable PWM output toggling
267 * @disable: disable PWM output toggling
270 int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
271 void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
272 int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
273 struct pwm_capture *result, unsigned long timeout);
274 int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
275 const struct pwm_state *state);
276 void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
277 struct pwm_state *state);
278 struct module *owner;
280 /* Only used by legacy drivers */
281 int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
282 int duty_ns, int period_ns);
283 int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
284 enum pwm_polarity polarity);
285 int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
286 void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
290 * struct pwm_chip - abstract a PWM controller
291 * @dev: device providing the PWMs
292 * @ops: callbacks for this PWM controller
293 * @base: number of first PWM controlled by this chip
294 * @npwm: number of PWMs controlled by this chip
295 * @of_xlate: request a PWM device given a device tree PWM specifier
296 * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
297 * @list: list node for internal use
298 * @pwms: array of PWM devices allocated by the framework
302 const struct pwm_ops *ops;
306 struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
307 const struct of_phandle_args *args);
308 unsigned int of_pwm_n_cells;
310 /* only used internally by the PWM framework */
311 struct list_head list;
312 struct pwm_device *pwms;
316 * struct pwm_capture - PWM capture data
317 * @period: period of the PWM signal (in nanoseconds)
318 * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
322 unsigned int duty_cycle;
325 #if IS_ENABLED(CONFIG_PWM)
327 struct pwm_device *pwm_request(int pwm_id, const char *label);
328 void pwm_free(struct pwm_device *pwm);
329 int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state);
330 int pwm_adjust_config(struct pwm_device *pwm);
333 * pwm_config() - change a PWM device configuration
335 * @duty_ns: "on" time (in nanoseconds)
336 * @period_ns: duration (in nanoseconds) of one cycle
338 * Returns: 0 on success or a negative error code on failure.
340 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
343 struct pwm_state state;
348 if (duty_ns < 0 || period_ns < 0)
351 pwm_get_state(pwm, &state);
352 if (state.duty_cycle == duty_ns && state.period == period_ns)
355 state.duty_cycle = duty_ns;
356 state.period = period_ns;
357 return pwm_apply_state(pwm, &state);
361 * pwm_enable() - start a PWM output toggling
364 * Returns: 0 on success or a negative error code on failure.
366 static inline int pwm_enable(struct pwm_device *pwm)
368 struct pwm_state state;
373 pwm_get_state(pwm, &state);
377 state.enabled = true;
378 return pwm_apply_state(pwm, &state);
382 * pwm_disable() - stop a PWM output toggling
385 static inline void pwm_disable(struct pwm_device *pwm)
387 struct pwm_state state;
392 pwm_get_state(pwm, &state);
396 state.enabled = false;
397 pwm_apply_state(pwm, &state);
400 /* PWM provider APIs */
401 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
402 unsigned long timeout);
403 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
404 void *pwm_get_chip_data(struct pwm_device *pwm);
406 int pwmchip_add(struct pwm_chip *chip);
407 void pwmchip_remove(struct pwm_chip *chip);
409 int devm_pwmchip_add(struct device *dev, struct pwm_chip *chip);
411 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
415 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
416 const struct of_phandle_args *args);
417 struct pwm_device *of_pwm_single_xlate(struct pwm_chip *pc,
418 const struct of_phandle_args *args);
420 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
421 struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,
423 void pwm_put(struct pwm_device *pwm);
425 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
426 struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
428 struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
429 struct fwnode_handle *fwnode,
432 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
435 return ERR_PTR(-ENODEV);
438 static inline void pwm_free(struct pwm_device *pwm)
443 static inline int pwm_apply_state(struct pwm_device *pwm,
444 const struct pwm_state *state)
450 static inline int pwm_adjust_config(struct pwm_device *pwm)
455 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
462 static inline int pwm_capture(struct pwm_device *pwm,
463 struct pwm_capture *result,
464 unsigned long timeout)
469 static inline int pwm_enable(struct pwm_device *pwm)
475 static inline void pwm_disable(struct pwm_device *pwm)
480 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
485 static inline void *pwm_get_chip_data(struct pwm_device *pwm)
490 static inline int pwmchip_add(struct pwm_chip *chip)
495 static inline int pwmchip_remove(struct pwm_chip *chip)
500 static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
505 return ERR_PTR(-ENODEV);
508 static inline struct pwm_device *pwm_get(struct device *dev,
509 const char *consumer)
512 return ERR_PTR(-ENODEV);
515 static inline struct pwm_device *of_pwm_get(struct device *dev,
516 struct device_node *np,
520 return ERR_PTR(-ENODEV);
523 static inline void pwm_put(struct pwm_device *pwm)
528 static inline struct pwm_device *devm_pwm_get(struct device *dev,
529 const char *consumer)
532 return ERR_PTR(-ENODEV);
535 static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
536 struct device_node *np,
540 return ERR_PTR(-ENODEV);
543 static inline struct pwm_device *
544 devm_fwnode_pwm_get(struct device *dev, struct fwnode_handle *fwnode,
548 return ERR_PTR(-ENODEV);
552 static inline void pwm_apply_args(struct pwm_device *pwm)
554 struct pwm_state state = { };
557 * PWM users calling pwm_apply_args() expect to have a fresh config
558 * where the polarity and period are set according to pwm_args info.
559 * The problem is, polarity can only be changed when the PWM is
562 * PWM drivers supporting hardware readout may declare the PWM device
563 * as enabled, and prevent polarity setting, which changes from the
564 * existing behavior, where all PWM devices are declared as disabled
565 * at startup (even if they are actually enabled), thus authorizing
568 * To fulfill this requirement, we apply a new state which disables
569 * the PWM device and set the reference period and polarity config.
571 * Note that PWM users requiring a smooth handover between the
572 * bootloader and the kernel (like critical regulators controlled by
573 * PWM devices) will have to switch to the atomic API and avoid calling
577 state.enabled = false;
578 state.polarity = pwm->args.polarity;
579 state.period = pwm->args.period;
580 state.usage_power = false;
582 pwm_apply_state(pwm, &state);
586 struct list_head list;
587 const char *provider;
592 enum pwm_polarity polarity;
593 const char *module; /* optional, may be NULL */
596 #define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, \
597 _period, _polarity, _module) \
599 .provider = _provider, \
604 .polarity = _polarity, \
608 #define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
609 PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
612 #if IS_ENABLED(CONFIG_PWM)
613 void pwm_add_table(struct pwm_lookup *table, size_t num);
614 void pwm_remove_table(struct pwm_lookup *table, size_t num);
616 static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
620 static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
625 #ifdef CONFIG_PWM_SYSFS
626 void pwmchip_sysfs_export(struct pwm_chip *chip);
627 void pwmchip_sysfs_unexport(struct pwm_chip *chip);
629 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
633 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
636 #endif /* CONFIG_PWM_SYSFS */
638 #endif /* __LINUX_PWM_H */