1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_PWM_H
3#define __LINUX_PWM_H
4
5#include <linux/cdev.h>
6#include <linux/device.h>
7#include <linux/err.h>
8#include <linux/gpio/driver.h>
9#include <linux/module.h>
10#include <linux/mutex.h>
11#include <linux/of.h>
12
13MODULE_IMPORT_NS("PWM");
14
15struct pwm_chip;
16
17/**
18 * enum pwm_polarity - polarity of a PWM signal
19 * @PWM_POLARITY_NORMAL: a high signal for the duration of the duty-
20 * cycle, followed by a low signal for the remainder of the pulse
21 * period
22 * @PWM_POLARITY_INVERSED: a low signal for the duration of the duty-
23 * cycle, followed by a high signal for the remainder of the pulse
24 * period
25 */
26enum pwm_polarity {
27 PWM_POLARITY_NORMAL,
28 PWM_POLARITY_INVERSED,
29};
30
31/**
32 * struct pwm_args - board-dependent PWM arguments
33 * @period: reference period
34 * @polarity: reference polarity
35 *
36 * This structure describes board-dependent arguments attached to a PWM
37 * device. These arguments are usually retrieved from the PWM lookup table or
38 * device tree.
39 *
40 * Do not confuse this with the PWM state: PWM arguments represent the initial
41 * configuration that users want to use on this PWM device rather than the
42 * current PWM hardware state.
43 */
44struct pwm_args {
45 u64 period;
46 enum pwm_polarity polarity;
47};
48
49enum {
50 PWMF_REQUESTED = 0,
51 PWMF_EXPORTED = 1,
52};
53
54/**
55 * struct pwm_waveform - description of a PWM waveform
56 * @period_length_ns: PWM period
57 * @duty_length_ns: PWM duty cycle
58 * @duty_offset_ns: offset of the rising edge from the period's start
59 *
60 * This is a representation of a PWM waveform alternative to struct pwm_state
61 * below. It's more expressive than struct pwm_state as it contains a
62 * duty_offset_ns and so can represent offsets other than zero (with .polarity =
63 * PWM_POLARITY_NORMAL) and period - duty_cycle (.polarity =
64 * PWM_POLARITY_INVERSED).
65 *
66 * Note there is no explicit bool for enabled. A "disabled" PWM is represented
67 * by .period_length_ns = 0. Note further that the behaviour of a "disabled" PWM
68 * is undefined. Depending on the hardware's capabilities it might drive the
69 * active or inactive level, go high-z or even continue to toggle.
70 *
71 * The unit for all three members is nanoseconds.
72 */
73struct pwm_waveform {
74 u64 period_length_ns;
75 u64 duty_length_ns;
76 u64 duty_offset_ns;
77};
78
79/*
80 * struct pwm_state - state of a PWM channel
81 * @period: PWM period (in nanoseconds)
82 * @duty_cycle: PWM duty cycle (in nanoseconds)
83 * @polarity: PWM polarity
84 * @enabled: PWM enabled status
85 * @usage_power: If set, the PWM driver is only required to maintain the power
86 * output but has more freedom regarding signal form.
87 * If supported, the signal can be optimized, for example to
88 * improve EMI by phase shifting individual channels.
89 */
90struct pwm_state {
91 u64 period;
92 u64 duty_cycle;
93 enum pwm_polarity polarity;
94 bool enabled;
95 bool usage_power;
96};
97
98/**
99 * struct pwm_device - PWM channel object
100 * @label: name of the PWM device
101 * @flags: flags associated with the PWM device
102 * @hwpwm: per-chip relative index of the PWM device
103 * @chip: PWM chip providing this PWM device
104 * @args: PWM arguments
105 * @state: last applied state
106 * @last: last implemented state (for PWM_DEBUG)
107 */
108struct pwm_device {
109 const char *label;
110 unsigned long flags;
111 unsigned int hwpwm;
112 struct pwm_chip *chip;
113
114 struct pwm_args args;
115 struct pwm_state state;
116 struct pwm_state last;
117};
118
119/**
120 * pwm_get_state() - retrieve the current PWM state
121 * @pwm: PWM device
122 * @state: state to fill with the current PWM state
123 *
124 * The returned PWM state represents the state that was applied by a previous call to
125 * pwm_apply_might_sleep(). Drivers may have to slightly tweak that state before programming it to
126 * hardware. If pwm_apply_might_sleep() was never called, this returns either the current hardware
127 * state (if supported) or the default settings.
128 */
129static inline void pwm_get_state(const struct pwm_device *pwm,
130 struct pwm_state *state)
131{
132 *state = pwm->state;
133}
134
135static inline bool pwm_is_enabled(const struct pwm_device *pwm)
136{
137 struct pwm_state state;
138
139 pwm_get_state(pwm, state: &state);
140
141 return state.enabled;
142}
143
144static inline u64 pwm_get_period(const struct pwm_device *pwm)
145{
146 struct pwm_state state;
147
148 pwm_get_state(pwm, state: &state);
149
150 return state.period;
151}
152
153static inline u64 pwm_get_duty_cycle(const struct pwm_device *pwm)
154{
155 struct pwm_state state;
156
157 pwm_get_state(pwm, state: &state);
158
159 return state.duty_cycle;
160}
161
162static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
163{
164 struct pwm_state state;
165
166 pwm_get_state(pwm, state: &state);
167
168 return state.polarity;
169}
170
171static inline void pwm_get_args(const struct pwm_device *pwm,
172 struct pwm_args *args)
173{
174 *args = pwm->args;
175}
176
177/**
178 * pwm_init_state() - prepare a new state to be applied with pwm_apply_might_sleep()
179 * @pwm: PWM device
180 * @state: state to fill with the prepared PWM state
181 *
182 * This functions prepares a state that can later be tweaked and applied
183 * to the PWM device with pwm_apply_might_sleep(). This is a convenient function
184 * that first retrieves the current PWM state and the replaces the period
185 * and polarity fields with the reference values defined in pwm->args.
186 * Once the function returns, you can adjust the ->enabled and ->duty_cycle
187 * fields according to your needs before calling pwm_apply_might_sleep().
188 *
189 * ->duty_cycle is initially set to zero to avoid cases where the current
190 * ->duty_cycle value exceed the pwm_args->period one, which would trigger
191 * an error if the user calls pwm_apply_might_sleep() without adjusting ->duty_cycle
192 * first.
193 */
194static inline void pwm_init_state(const struct pwm_device *pwm,
195 struct pwm_state *state)
196{
197 struct pwm_args args;
198
199 /* First get the current state. */
200 pwm_get_state(pwm, state);
201
202 /* Then fill it with the reference config */
203 pwm_get_args(pwm, args: &args);
204
205 state->period = args.period;
206 state->polarity = args.polarity;
207 state->duty_cycle = 0;
208 state->usage_power = false;
209}
210
211/**
212 * pwm_get_relative_duty_cycle() - Get a relative duty cycle value
213 * @state: PWM state to extract the duty cycle from
214 * @scale: target scale of the relative duty cycle
215 *
216 * This functions converts the absolute duty cycle stored in @state (expressed
217 * in nanosecond) into a value relative to the period.
218 *
219 * For example if you want to get the duty_cycle expressed in percent, call:
220 *
221 * pwm_get_state(pwm, &state);
222 * duty = pwm_get_relative_duty_cycle(&state, 100);
223 *
224 * Returns: rounded relative duty cycle multiplied by @scale
225 */
226static inline unsigned int
227pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
228{
229 if (!state->period)
230 return 0;
231
232 return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
233 state->period);
234}
235
236/**
237 * pwm_set_relative_duty_cycle() - Set a relative duty cycle value
238 * @state: PWM state to fill
239 * @duty_cycle: relative duty cycle value
240 * @scale: scale in which @duty_cycle is expressed
241 *
242 * This functions converts a relative into an absolute duty cycle (expressed
243 * in nanoseconds), and puts the result in state->duty_cycle.
244 *
245 * For example if you want to configure a 50% duty cycle, call:
246 *
247 * pwm_init_state(pwm, &state);
248 * pwm_set_relative_duty_cycle(&state, 50, 100);
249 * pwm_apply_might_sleep(pwm, &state);
250 *
251 * Returns: 0 on success or ``-EINVAL`` if @duty_cycle and/or @scale are
252 * inconsistent (@scale == 0 or @duty_cycle > @scale)
253 */
254static inline int
255pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
256 unsigned int scale)
257{
258 if (!scale || duty_cycle > scale)
259 return -EINVAL;
260
261 state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
262 state->period,
263 scale);
264
265 return 0;
266}
267
268/**
269 * struct pwm_capture - PWM capture data
270 * @period: period of the PWM signal (in nanoseconds)
271 * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
272 */
273struct pwm_capture {
274 unsigned int period;
275 unsigned int duty_cycle;
276};
277
278#define PWM_WFHWSIZE 20
279
280/**
281 * struct pwm_ops - PWM controller operations
282 * @request: optional hook for requesting a PWM
283 * @free: optional hook for freeing a PWM
284 * @capture: capture and report PWM signal
285 * @sizeof_wfhw: size (in bytes) of driver specific waveform presentation
286 * @round_waveform_tohw: convert a struct pwm_waveform to driver specific presentation
287 * @round_waveform_fromhw: convert a driver specific waveform presentation to struct pwm_waveform
288 * @read_waveform: read driver specific waveform presentation from hardware
289 * @write_waveform: write driver specific waveform presentation to hardware
290 * @apply: atomically apply a new PWM config
291 * @get_state: get the current PWM state.
292 */
293struct pwm_ops {
294 int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
295 void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
296 int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
297 struct pwm_capture *result, unsigned long timeout);
298
299 size_t sizeof_wfhw;
300 int (*round_waveform_tohw)(struct pwm_chip *chip, struct pwm_device *pwm,
301 const struct pwm_waveform *wf, void *wfhw);
302 int (*round_waveform_fromhw)(struct pwm_chip *chip, struct pwm_device *pwm,
303 const void *wfhw, struct pwm_waveform *wf);
304 int (*read_waveform)(struct pwm_chip *chip, struct pwm_device *pwm,
305 void *wfhw);
306 int (*write_waveform)(struct pwm_chip *chip, struct pwm_device *pwm,
307 const void *wfhw);
308
309 int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
310 const struct pwm_state *state);
311 int (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
312 struct pwm_state *state);
313};
314
315/**
316 * struct pwm_chip - abstract a PWM controller
317 * @dev: device providing the PWMs
318 * @cdev: &struct cdev for this device
319 * @ops: callbacks for this PWM controller
320 * @owner: module providing this chip
321 * @id: unique number of this PWM chip
322 * @npwm: number of PWMs controlled by this chip
323 * @of_xlate: request a PWM device given a device tree PWM specifier
324 * @atomic: can the driver's ->apply() be called in atomic context
325 * @gpio: &struct gpio_chip to operate this PWM chip's lines as GPO
326 * @uses_pwmchip_alloc: signals if pwmchip_allow was used to allocate this chip
327 * @operational: signals if the chip can be used (or is already deregistered)
328 * @nonatomic_lock: mutex for nonatomic chips
329 * @atomic_lock: mutex for atomic chips
330 * @pwms: array of PWM devices allocated by the framework
331 */
332struct pwm_chip {
333 struct device dev;
334 struct cdev cdev;
335 const struct pwm_ops *ops;
336 struct module *owner;
337 unsigned int id;
338 unsigned int npwm;
339
340 struct pwm_device * (*of_xlate)(struct pwm_chip *chip,
341 const struct of_phandle_args *args);
342 bool atomic;
343
344 /* only used internally by the PWM framework */
345 struct gpio_chip gpio;
346 bool uses_pwmchip_alloc;
347 bool operational;
348 union {
349 /*
350 * depending on the chip being atomic or not either the mutex or
351 * the spinlock is used. It protects .operational and
352 * synchronizes the callbacks in .ops
353 */
354 struct mutex nonatomic_lock;
355 spinlock_t atomic_lock;
356 };
357 struct pwm_device pwms[] __counted_by(npwm);
358};
359
360/**
361 * pwmchip_supports_waveform() - checks if the given chip supports waveform callbacks
362 * @chip: The pwm_chip to test
363 *
364 * Returns: true iff the pwm chip support the waveform functions like
365 * pwm_set_waveform_might_sleep() and pwm_round_waveform_might_sleep()
366 */
367static inline bool pwmchip_supports_waveform(struct pwm_chip *chip)
368{
369 /*
370 * only check for .write_waveform(). If that is available,
371 * .round_waveform_tohw() and .round_waveform_fromhw() asserted to be
372 * available, too, in pwmchip_add().
373 */
374 return chip->ops->write_waveform != NULL;
375}
376
377static inline struct device *pwmchip_parent(const struct pwm_chip *chip)
378{
379 return chip->dev.parent;
380}
381
382static inline void *pwmchip_get_drvdata(const struct pwm_chip *chip)
383{
384 return dev_get_drvdata(dev: &chip->dev);
385}
386
387static inline void pwmchip_set_drvdata(struct pwm_chip *chip, void *data)
388{
389 dev_set_drvdata(dev: &chip->dev, data);
390}
391
392#if IS_REACHABLE(CONFIG_PWM)
393
394/* PWM consumer APIs */
395int pwm_round_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *wf);
396int pwm_get_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *wf);
397int pwm_set_waveform_might_sleep(struct pwm_device *pwm, const struct pwm_waveform *wf, bool exact);
398int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state);
399int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state);
400int pwm_get_state_hw(struct pwm_device *pwm, struct pwm_state *state);
401int pwm_adjust_config(struct pwm_device *pwm);
402
403/**
404 * pwm_config() - change a PWM device configuration
405 * @pwm: PWM device
406 * @duty_ns: "on" time (in nanoseconds)
407 * @period_ns: duration (in nanoseconds) of one cycle
408 *
409 * Returns: 0 on success or a negative error code on failure.
410 */
411static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
412 int period_ns)
413{
414 struct pwm_state state;
415
416 if (!pwm)
417 return -EINVAL;
418
419 if (duty_ns < 0 || period_ns < 0)
420 return -EINVAL;
421
422 pwm_get_state(pwm, state: &state);
423 if (state.duty_cycle == duty_ns && state.period == period_ns)
424 return 0;
425
426 state.duty_cycle = duty_ns;
427 state.period = period_ns;
428 return pwm_apply_might_sleep(pwm, state: &state);
429}
430
431/**
432 * pwm_enable() - start a PWM output toggling
433 * @pwm: PWM device
434 *
435 * Returns: 0 on success or a negative error code on failure.
436 */
437static inline int pwm_enable(struct pwm_device *pwm)
438{
439 struct pwm_state state;
440
441 if (!pwm)
442 return -EINVAL;
443
444 pwm_get_state(pwm, state: &state);
445 if (state.enabled)
446 return 0;
447
448 state.enabled = true;
449 return pwm_apply_might_sleep(pwm, state: &state);
450}
451
452/**
453 * pwm_disable() - stop a PWM output toggling
454 * @pwm: PWM device
455 */
456static inline void pwm_disable(struct pwm_device *pwm)
457{
458 struct pwm_state state;
459
460 if (!pwm)
461 return;
462
463 pwm_get_state(pwm, state: &state);
464 if (!state.enabled)
465 return;
466
467 state.enabled = false;
468 pwm_apply_might_sleep(pwm, state: &state);
469}
470
471/**
472 * pwm_might_sleep() - is pwm_apply_atomic() supported?
473 * @pwm: PWM device
474 *
475 * Returns: false if pwm_apply_atomic() can be called from atomic context.
476 */
477static inline bool pwm_might_sleep(struct pwm_device *pwm)
478{
479 return !pwm->chip->atomic;
480}
481
482/* PWM provider APIs */
483void pwmchip_put(struct pwm_chip *chip);
484struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv);
485struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv);
486
487int __pwmchip_add(struct pwm_chip *chip, struct module *owner);
488#define pwmchip_add(chip) __pwmchip_add(chip, THIS_MODULE)
489void pwmchip_remove(struct pwm_chip *chip);
490
491/*
492 * For FFI wrapper use only:
493 * The Rust PWM abstraction needs this to properly free the pwm_chip.
494 */
495void pwmchip_release(struct device *dev);
496
497int __devm_pwmchip_add(struct device *dev, struct pwm_chip *chip, struct module *owner);
498#define devm_pwmchip_add(dev, chip) __devm_pwmchip_add(dev, chip, THIS_MODULE)
499
500struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *chip,
501 const struct of_phandle_args *args);
502struct pwm_device *of_pwm_single_xlate(struct pwm_chip *chip,
503 const struct of_phandle_args *args);
504
505struct pwm_device *pwm_get(struct device *dev, const char *con_id);
506void pwm_put(struct pwm_device *pwm);
507
508struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
509struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
510 struct fwnode_handle *fwnode,
511 const char *con_id);
512#else
513static inline bool pwm_might_sleep(struct pwm_device *pwm)
514{
515 return true;
516}
517
518static inline int pwm_apply_might_sleep(struct pwm_device *pwm,
519 const struct pwm_state *state)
520{
521 might_sleep();
522 return -EOPNOTSUPP;
523}
524
525static inline int pwm_apply_atomic(struct pwm_device *pwm,
526 const struct pwm_state *state)
527{
528 return -EOPNOTSUPP;
529}
530
531static inline int pwm_get_state_hw(struct pwm_device *pwm, struct pwm_state *state)
532{
533 return -EOPNOTSUPP;
534}
535
536static inline int pwm_adjust_config(struct pwm_device *pwm)
537{
538 return -EOPNOTSUPP;
539}
540
541static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
542 int period_ns)
543{
544 might_sleep();
545 return -EINVAL;
546}
547
548static inline int pwm_enable(struct pwm_device *pwm)
549{
550 might_sleep();
551 return -EINVAL;
552}
553
554static inline void pwm_disable(struct pwm_device *pwm)
555{
556 might_sleep();
557}
558
559static inline void pwmchip_put(struct pwm_chip *chip)
560{
561}
562
563static inline struct pwm_chip *pwmchip_alloc(struct device *parent,
564 unsigned int npwm,
565 size_t sizeof_priv)
566{
567 return ERR_PTR(-EINVAL);
568}
569
570static inline struct pwm_chip *devm_pwmchip_alloc(struct device *parent,
571 unsigned int npwm,
572 size_t sizeof_priv)
573{
574 return pwmchip_alloc(parent, npwm, sizeof_priv);
575}
576
577static inline int pwmchip_add(struct pwm_chip *chip)
578{
579 return -EINVAL;
580}
581
582static inline int pwmchip_remove(struct pwm_chip *chip)
583{
584 return -EINVAL;
585}
586
587static inline int devm_pwmchip_add(struct device *dev, struct pwm_chip *chip)
588{
589 return -EINVAL;
590}
591
592static inline struct pwm_device *pwm_get(struct device *dev,
593 const char *consumer)
594{
595 might_sleep();
596 return ERR_PTR(-ENODEV);
597}
598
599static inline void pwm_put(struct pwm_device *pwm)
600{
601 might_sleep();
602}
603
604static inline struct pwm_device *devm_pwm_get(struct device *dev,
605 const char *consumer)
606{
607 might_sleep();
608 return ERR_PTR(-ENODEV);
609}
610
611static inline struct pwm_device *
612devm_fwnode_pwm_get(struct device *dev, struct fwnode_handle *fwnode,
613 const char *con_id)
614{
615 might_sleep();
616 return ERR_PTR(-ENODEV);
617}
618#endif
619
620struct pwm_lookup {
621 struct list_head list;
622 const char *provider;
623 unsigned int index;
624 const char *dev_id;
625 const char *con_id;
626 unsigned int period;
627 enum pwm_polarity polarity;
628 const char *module; /* optional, may be NULL */
629};
630
631#define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, \
632 _period, _polarity, _module) \
633 { \
634 .provider = _provider, \
635 .index = _index, \
636 .dev_id = _dev_id, \
637 .con_id = _con_id, \
638 .period = _period, \
639 .polarity = _polarity, \
640 .module = _module, \
641 }
642
643#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
644 PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
645 _polarity, NULL)
646
647#if IS_REACHABLE(CONFIG_PWM)
648void pwm_add_table(struct pwm_lookup *table, size_t num);
649void pwm_remove_table(struct pwm_lookup *table, size_t num);
650#else
651static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
652{
653}
654
655static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
656{
657}
658#endif
659
660#endif /* __LINUX_PWM_H */
661

source code of linux/include/linux/pwm.h