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