1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_PWM_H
3#define __LINUX_PWM_H
4
5#include <linux/err.h>
6#include <linux/mutex.h>
7#include <linux/of.h>
8
9struct pwm_chip;
10
11/**
12 * enum pwm_polarity - polarity of a PWM signal
13 * @PWM_POLARITY_NORMAL: a high signal for the duration of the duty-
14 * cycle, followed by a low signal for the remainder of the pulse
15 * period
16 * @PWM_POLARITY_INVERSED: a low signal for the duration of the duty-
17 * cycle, followed by a high signal for the remainder of the pulse
18 * period
19 */
20enum pwm_polarity {
21 PWM_POLARITY_NORMAL,
22 PWM_POLARITY_INVERSED,
23};
24
25/**
26 * struct pwm_args - board-dependent PWM arguments
27 * @period: reference period
28 * @polarity: reference polarity
29 *
30 * This structure describes board-dependent arguments attached to a PWM
31 * device. These arguments are usually retrieved from the PWM lookup table or
32 * device tree.
33 *
34 * Do not confuse this with the PWM state: PWM arguments represent the initial
35 * configuration that users want to use on this PWM device rather than the
36 * current PWM hardware state.
37 */
38struct pwm_args {
39 u64 period;
40 enum pwm_polarity polarity;
41};
42
43enum {
44 PWMF_REQUESTED = 1 << 0,
45 PWMF_EXPORTED = 1 << 1,
46};
47
48/*
49 * struct pwm_state - state of a PWM channel
50 * @period: PWM period (in nanoseconds)
51 * @duty_cycle: PWM duty cycle (in nanoseconds)
52 * @polarity: PWM polarity
53 * @enabled: PWM enabled status
54 * @usage_power: If set, the PWM driver is only required to maintain the power
55 * output but has more freedom regarding signal form.
56 * If supported, the signal can be optimized, for example to
57 * improve EMI by phase shifting individual channels.
58 */
59struct pwm_state {
60 u64 period;
61 u64 duty_cycle;
62 enum pwm_polarity polarity;
63 bool enabled;
64 bool usage_power;
65};
66
67/**
68 * struct pwm_device - PWM channel object
69 * @label: name of the PWM device
70 * @flags: flags associated with the PWM device
71 * @hwpwm: per-chip relative index of the PWM device
72 * @pwm: global index of the PWM device
73 * @chip: PWM chip providing this PWM device
74 * @chip_data: chip-private data associated with the PWM device
75 * @args: PWM arguments
76 * @state: last applied state
77 * @last: last implemented state (for PWM_DEBUG)
78 */
79struct pwm_device {
80 const char *label;
81 unsigned long flags;
82 unsigned int hwpwm;
83 unsigned int pwm;
84 struct pwm_chip *chip;
85 void *chip_data;
86
87 struct pwm_args args;
88 struct pwm_state state;
89 struct pwm_state last;
90};
91
92/**
93 * pwm_get_state() - retrieve the current PWM state
94 * @pwm: PWM device
95 * @state: state to fill with the current PWM state
96 *
97 * The returned PWM state represents the state that was applied by a previous call to
98 * pwm_apply_state(). Drivers may have to slightly tweak that state before programming it to
99 * hardware. If pwm_apply_state() was never called, this returns either the current hardware
100 * state (if supported) or the default settings.
101 */
102static inline void pwm_get_state(const struct pwm_device *pwm,
103 struct pwm_state *state)
104{
105 *state = pwm->state;
106}
107
108static inline bool pwm_is_enabled(const struct pwm_device *pwm)
109{
110 struct pwm_state state;
111
112 pwm_get_state(pwm, state: &state);
113
114 return state.enabled;
115}
116
117static inline void pwm_set_period(struct pwm_device *pwm, u64 period)
118{
119 if (pwm)
120 pwm->state.period = period;
121}
122
123static inline u64 pwm_get_period(const struct pwm_device *pwm)
124{
125 struct pwm_state state;
126
127 pwm_get_state(pwm, state: &state);
128
129 return state.period;
130}
131
132static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
133{
134 if (pwm)
135 pwm->state.duty_cycle = duty;
136}
137
138static inline u64 pwm_get_duty_cycle(const struct pwm_device *pwm)
139{
140 struct pwm_state state;
141
142 pwm_get_state(pwm, state: &state);
143
144 return state.duty_cycle;
145}
146
147static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
148{
149 struct pwm_state state;
150
151 pwm_get_state(pwm, state: &state);
152
153 return state.polarity;
154}
155
156static inline void pwm_get_args(const struct pwm_device *pwm,
157 struct pwm_args *args)
158{
159 *args = pwm->args;
160}
161
162/**
163 * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
164 * @pwm: PWM device
165 * @state: state to fill with the prepared PWM state
166 *
167 * This functions prepares a state that can later be tweaked and applied
168 * to the PWM device with pwm_apply_state(). This is a convenient function
169 * that first retrieves the current PWM state and the replaces the period
170 * and polarity fields with the reference values defined in pwm->args.
171 * Once the function returns, you can adjust the ->enabled and ->duty_cycle
172 * fields according to your needs before calling pwm_apply_state().
173 *
174 * ->duty_cycle is initially set to zero to avoid cases where the current
175 * ->duty_cycle value exceed the pwm_args->period one, which would trigger
176 * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
177 * first.
178 */
179static inline void pwm_init_state(const struct pwm_device *pwm,
180 struct pwm_state *state)
181{
182 struct pwm_args args;
183
184 /* First get the current state. */
185 pwm_get_state(pwm, state);
186
187 /* Then fill it with the reference config */
188 pwm_get_args(pwm, args: &args);
189
190 state->period = args.period;
191 state->polarity = args.polarity;
192 state->duty_cycle = 0;
193 state->usage_power = false;
194}
195
196/**
197 * pwm_get_relative_duty_cycle() - Get a relative duty cycle value
198 * @state: PWM state to extract the duty cycle from
199 * @scale: target scale of the relative duty cycle
200 *
201 * This functions converts the absolute duty cycle stored in @state (expressed
202 * in nanosecond) into a value relative to the period.
203 *
204 * For example if you want to get the duty_cycle expressed in percent, call:
205 *
206 * pwm_get_state(pwm, &state);
207 * duty = pwm_get_relative_duty_cycle(&state, 100);
208 */
209static inline unsigned int
210pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
211{
212 if (!state->period)
213 return 0;
214
215 return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
216 state->period);
217}
218
219/**
220 * pwm_set_relative_duty_cycle() - Set a relative duty cycle value
221 * @state: PWM state to fill
222 * @duty_cycle: relative duty cycle value
223 * @scale: scale in which @duty_cycle is expressed
224 *
225 * This functions converts a relative into an absolute duty cycle (expressed
226 * in nanoseconds), and puts the result in state->duty_cycle.
227 *
228 * For example if you want to configure a 50% duty cycle, call:
229 *
230 * pwm_init_state(pwm, &state);
231 * pwm_set_relative_duty_cycle(&state, 50, 100);
232 * pwm_apply_state(pwm, &state);
233 *
234 * This functions returns -EINVAL if @duty_cycle and/or @scale are
235 * inconsistent (@scale == 0 or @duty_cycle > @scale).
236 */
237static inline int
238pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
239 unsigned int scale)
240{
241 if (!scale || duty_cycle > scale)
242 return -EINVAL;
243
244 state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
245 state->period,
246 scale);
247
248 return 0;
249}
250
251/**
252 * struct pwm_capture - PWM capture data
253 * @period: period of the PWM signal (in nanoseconds)
254 * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
255 */
256struct pwm_capture {
257 unsigned int period;
258 unsigned int duty_cycle;
259};
260
261/**
262 * struct pwm_ops - PWM controller operations
263 * @request: optional hook for requesting a PWM
264 * @free: optional hook for freeing a PWM
265 * @capture: capture and report PWM signal
266 * @apply: atomically apply a new PWM config
267 * @get_state: get the current PWM state. This function is only
268 * called once per PWM device when the PWM chip is
269 * registered.
270 * @owner: helps prevent removal of modules exporting active PWMs
271 */
272struct pwm_ops {
273 int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
274 void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
275 int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
276 struct pwm_capture *result, unsigned long timeout);
277 int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
278 const struct pwm_state *state);
279 int (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
280 struct pwm_state *state);
281 struct module *owner;
282};
283
284/**
285 * struct pwm_chip - abstract a PWM controller
286 * @dev: device providing the PWMs
287 * @ops: callbacks for this PWM controller
288 * @base: number of first PWM controlled by this chip
289 * @npwm: number of PWMs controlled by this chip
290 * @of_xlate: request a PWM device given a device tree PWM specifier
291 * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
292 * @list: list node for internal use
293 * @pwms: array of PWM devices allocated by the framework
294 */
295struct pwm_chip {
296 struct device *dev;
297 const struct pwm_ops *ops;
298 int base;
299 unsigned int npwm;
300
301 struct pwm_device * (*of_xlate)(struct pwm_chip *chip,
302 const struct of_phandle_args *args);
303 unsigned int of_pwm_n_cells;
304
305 /* only used internally by the PWM framework */
306 struct list_head list;
307 struct pwm_device *pwms;
308};
309
310#if IS_ENABLED(CONFIG_PWM)
311/* PWM user APIs */
312int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state);
313int pwm_adjust_config(struct pwm_device *pwm);
314
315/**
316 * pwm_config() - change a PWM device configuration
317 * @pwm: PWM device
318 * @duty_ns: "on" time (in nanoseconds)
319 * @period_ns: duration (in nanoseconds) of one cycle
320 *
321 * Returns: 0 on success or a negative error code on failure.
322 */
323static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
324 int period_ns)
325{
326 struct pwm_state state;
327
328 if (!pwm)
329 return -EINVAL;
330
331 if (duty_ns < 0 || period_ns < 0)
332 return -EINVAL;
333
334 pwm_get_state(pwm, state: &state);
335 if (state.duty_cycle == duty_ns && state.period == period_ns)
336 return 0;
337
338 state.duty_cycle = duty_ns;
339 state.period = period_ns;
340 return pwm_apply_state(pwm, state: &state);
341}
342
343/**
344 * pwm_enable() - start a PWM output toggling
345 * @pwm: PWM device
346 *
347 * Returns: 0 on success or a negative error code on failure.
348 */
349static inline int pwm_enable(struct pwm_device *pwm)
350{
351 struct pwm_state state;
352
353 if (!pwm)
354 return -EINVAL;
355
356 pwm_get_state(pwm, state: &state);
357 if (state.enabled)
358 return 0;
359
360 state.enabled = true;
361 return pwm_apply_state(pwm, state: &state);
362}
363
364/**
365 * pwm_disable() - stop a PWM output toggling
366 * @pwm: PWM device
367 */
368static inline void pwm_disable(struct pwm_device *pwm)
369{
370 struct pwm_state state;
371
372 if (!pwm)
373 return;
374
375 pwm_get_state(pwm, state: &state);
376 if (!state.enabled)
377 return;
378
379 state.enabled = false;
380 pwm_apply_state(pwm, state: &state);
381}
382
383/* PWM provider APIs */
384int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
385 unsigned long timeout);
386int pwm_set_chip_data(struct pwm_device *pwm, void *data);
387void *pwm_get_chip_data(struct pwm_device *pwm);
388
389int pwmchip_add(struct pwm_chip *chip);
390void pwmchip_remove(struct pwm_chip *chip);
391
392int devm_pwmchip_add(struct device *dev, struct pwm_chip *chip);
393
394struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
395 unsigned int index,
396 const char *label);
397
398struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *chip,
399 const struct of_phandle_args *args);
400struct pwm_device *of_pwm_single_xlate(struct pwm_chip *chip,
401 const struct of_phandle_args *args);
402
403struct pwm_device *pwm_get(struct device *dev, const char *con_id);
404void pwm_put(struct pwm_device *pwm);
405
406struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
407struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
408 struct fwnode_handle *fwnode,
409 const char *con_id);
410#else
411static inline int pwm_apply_state(struct pwm_device *pwm,
412 const struct pwm_state *state)
413{
414 might_sleep();
415 return -ENOTSUPP;
416}
417
418static inline int pwm_adjust_config(struct pwm_device *pwm)
419{
420 return -ENOTSUPP;
421}
422
423static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
424 int period_ns)
425{
426 might_sleep();
427 return -EINVAL;
428}
429
430static inline int pwm_enable(struct pwm_device *pwm)
431{
432 might_sleep();
433 return -EINVAL;
434}
435
436static inline void pwm_disable(struct pwm_device *pwm)
437{
438 might_sleep();
439}
440
441static inline int pwm_capture(struct pwm_device *pwm,
442 struct pwm_capture *result,
443 unsigned long timeout)
444{
445 return -EINVAL;
446}
447
448static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
449{
450 return -EINVAL;
451}
452
453static inline void *pwm_get_chip_data(struct pwm_device *pwm)
454{
455 return NULL;
456}
457
458static inline int pwmchip_add(struct pwm_chip *chip)
459{
460 return -EINVAL;
461}
462
463static inline int pwmchip_remove(struct pwm_chip *chip)
464{
465 return -EINVAL;
466}
467
468static inline int devm_pwmchip_add(struct device *dev, struct pwm_chip *chip)
469{
470 return -EINVAL;
471}
472
473static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
474 unsigned int index,
475 const char *label)
476{
477 might_sleep();
478 return ERR_PTR(-ENODEV);
479}
480
481static inline struct pwm_device *pwm_get(struct device *dev,
482 const char *consumer)
483{
484 might_sleep();
485 return ERR_PTR(-ENODEV);
486}
487
488static inline void pwm_put(struct pwm_device *pwm)
489{
490 might_sleep();
491}
492
493static inline struct pwm_device *devm_pwm_get(struct device *dev,
494 const char *consumer)
495{
496 might_sleep();
497 return ERR_PTR(-ENODEV);
498}
499
500static inline struct pwm_device *
501devm_fwnode_pwm_get(struct device *dev, struct fwnode_handle *fwnode,
502 const char *con_id)
503{
504 might_sleep();
505 return ERR_PTR(-ENODEV);
506}
507#endif
508
509static inline void pwm_apply_args(struct pwm_device *pwm)
510{
511 struct pwm_state state = { };
512
513 /*
514 * PWM users calling pwm_apply_args() expect to have a fresh config
515 * where the polarity and period are set according to pwm_args info.
516 * The problem is, polarity can only be changed when the PWM is
517 * disabled.
518 *
519 * PWM drivers supporting hardware readout may declare the PWM device
520 * as enabled, and prevent polarity setting, which changes from the
521 * existing behavior, where all PWM devices are declared as disabled
522 * at startup (even if they are actually enabled), thus authorizing
523 * polarity setting.
524 *
525 * To fulfill this requirement, we apply a new state which disables
526 * the PWM device and set the reference period and polarity config.
527 *
528 * Note that PWM users requiring a smooth handover between the
529 * bootloader and the kernel (like critical regulators controlled by
530 * PWM devices) will have to switch to the atomic API and avoid calling
531 * pwm_apply_args().
532 */
533
534 state.enabled = false;
535 state.polarity = pwm->args.polarity;
536 state.period = pwm->args.period;
537 state.usage_power = false;
538
539 pwm_apply_state(pwm, state: &state);
540}
541
542struct pwm_lookup {
543 struct list_head list;
544 const char *provider;
545 unsigned int index;
546 const char *dev_id;
547 const char *con_id;
548 unsigned int period;
549 enum pwm_polarity polarity;
550 const char *module; /* optional, may be NULL */
551};
552
553#define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, \
554 _period, _polarity, _module) \
555 { \
556 .provider = _provider, \
557 .index = _index, \
558 .dev_id = _dev_id, \
559 .con_id = _con_id, \
560 .period = _period, \
561 .polarity = _polarity, \
562 .module = _module, \
563 }
564
565#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
566 PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
567 _polarity, NULL)
568
569#if IS_ENABLED(CONFIG_PWM)
570void pwm_add_table(struct pwm_lookup *table, size_t num);
571void pwm_remove_table(struct pwm_lookup *table, size_t num);
572#else
573static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
574{
575}
576
577static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
578{
579}
580#endif
581
582#ifdef CONFIG_PWM_SYSFS
583void pwmchip_sysfs_export(struct pwm_chip *chip);
584void pwmchip_sysfs_unexport(struct pwm_chip *chip);
585#else
586static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
587{
588}
589
590static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
591{
592}
593#endif /* CONFIG_PWM_SYSFS */
594
595#endif /* __LINUX_PWM_H */
596

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