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 
9 struct pwm_capture;
10 struct seq_file;
11 
12 struct pwm_chip;
13 
14 /**
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
18  * period
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
21  * period
22  */
23 enum pwm_polarity {
24 	PWM_POLARITY_NORMAL,
25 	PWM_POLARITY_INVERSED,
26 };
27 
28 /**
29  * struct pwm_args - board-dependent PWM arguments
30  * @period: reference period
31  * @polarity: reference polarity
32  *
33  * This structure describes board-dependent arguments attached to a PWM
34  * device. These arguments are usually retrieved from the PWM lookup table or
35  * device tree.
36  *
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.
40  */
41 struct pwm_args {
42 	unsigned int period;
43 	enum pwm_polarity polarity;
44 };
45 
46 enum {
47 	PWMF_REQUESTED = 1 << 0,
48 	PWMF_EXPORTED = 1 << 1,
49 };
50 
51 /*
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  */
58 struct pwm_state {
59 	unsigned int period;
60 	unsigned int duty_cycle;
61 	enum pwm_polarity polarity;
62 	bool enabled;
63 };
64 
65 /**
66  * struct pwm_device - PWM channel object
67  * @label: name of the PWM device
68  * @flags: flags associated with the PWM device
69  * @hwpwm: per-chip relative index of the PWM device
70  * @pwm: global index of the PWM device
71  * @chip: PWM chip providing this PWM device
72  * @chip_data: chip-private data associated with the PWM device
73  * @args: PWM arguments
74  * @state: curent PWM channel state
75  */
76 struct pwm_device {
77 	const char *label;
78 	unsigned long flags;
79 	unsigned int hwpwm;
80 	unsigned int pwm;
81 	struct pwm_chip *chip;
82 	void *chip_data;
83 
84 	struct pwm_args args;
85 	struct pwm_state state;
86 };
87 
88 /**
89  * pwm_get_state() - retrieve the current PWM state
90  * @pwm: PWM device
91  * @state: state to fill with the current PWM state
92  */
pwm_get_state(const struct pwm_device * pwm,struct pwm_state * state)93 static inline void pwm_get_state(const struct pwm_device *pwm,
94 				 struct pwm_state *state)
95 {
96 	*state = pwm->state;
97 }
98 
pwm_is_enabled(const struct pwm_device * pwm)99 static inline bool pwm_is_enabled(const struct pwm_device *pwm)
100 {
101 	struct pwm_state state;
102 
103 	pwm_get_state(pwm, &state);
104 
105 	return state.enabled;
106 }
107 
pwm_set_period(struct pwm_device * pwm,unsigned int period)108 static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
109 {
110 	if (pwm)
111 		pwm->state.period = period;
112 }
113 
pwm_get_period(const struct pwm_device * pwm)114 static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
115 {
116 	struct pwm_state state;
117 
118 	pwm_get_state(pwm, &state);
119 
120 	return state.period;
121 }
122 
pwm_set_duty_cycle(struct pwm_device * pwm,unsigned int duty)123 static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
124 {
125 	if (pwm)
126 		pwm->state.duty_cycle = duty;
127 }
128 
pwm_get_duty_cycle(const struct pwm_device * pwm)129 static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
130 {
131 	struct pwm_state state;
132 
133 	pwm_get_state(pwm, &state);
134 
135 	return state.duty_cycle;
136 }
137 
pwm_get_polarity(const struct pwm_device * pwm)138 static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
139 {
140 	struct pwm_state state;
141 
142 	pwm_get_state(pwm, &state);
143 
144 	return state.polarity;
145 }
146 
pwm_get_args(const struct pwm_device * pwm,struct pwm_args * args)147 static inline void pwm_get_args(const struct pwm_device *pwm,
148 				struct pwm_args *args)
149 {
150 	*args = pwm->args;
151 }
152 
153 /**
154  * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
155  * @pwm: PWM device
156  * @state: state to fill with the prepared PWM state
157  *
158  * This functions prepares a state that can later be tweaked and applied
159  * to the PWM device with pwm_apply_state(). This is a convenient function
160  * that first retrieves the current PWM state and the replaces the period
161  * and polarity fields with the reference values defined in pwm->args.
162  * Once the function returns, you can adjust the ->enabled and ->duty_cycle
163  * fields according to your needs before calling pwm_apply_state().
164  *
165  * ->duty_cycle is initially set to zero to avoid cases where the current
166  * ->duty_cycle value exceed the pwm_args->period one, which would trigger
167  * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
168  * first.
169  */
pwm_init_state(const struct pwm_device * pwm,struct pwm_state * state)170 static inline void pwm_init_state(const struct pwm_device *pwm,
171 				  struct pwm_state *state)
172 {
173 	struct pwm_args args;
174 
175 	/* First get the current state. */
176 	pwm_get_state(pwm, state);
177 
178 	/* Then fill it with the reference config */
179 	pwm_get_args(pwm, &args);
180 
181 	state->period = args.period;
182 	state->polarity = args.polarity;
183 	state->duty_cycle = 0;
184 }
185 
186 /**
187  * pwm_get_relative_duty_cycle() - Get a relative duty cycle value
188  * @state: PWM state to extract the duty cycle from
189  * @scale: target scale of the relative duty cycle
190  *
191  * This functions converts the absolute duty cycle stored in @state (expressed
192  * in nanosecond) into a value relative to the period.
193  *
194  * For example if you want to get the duty_cycle expressed in percent, call:
195  *
196  * pwm_get_state(pwm, &state);
197  * duty = pwm_get_relative_duty_cycle(&state, 100);
198  */
199 static inline unsigned int
pwm_get_relative_duty_cycle(const struct pwm_state * state,unsigned int scale)200 pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
201 {
202 	if (!state->period)
203 		return 0;
204 
205 	return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
206 				     state->period);
207 }
208 
209 /**
210  * pwm_set_relative_duty_cycle() - Set a relative duty cycle value
211  * @state: PWM state to fill
212  * @duty_cycle: relative duty cycle value
213  * @scale: scale in which @duty_cycle is expressed
214  *
215  * This functions converts a relative into an absolute duty cycle (expressed
216  * in nanoseconds), and puts the result in state->duty_cycle.
217  *
218  * For example if you want to configure a 50% duty cycle, call:
219  *
220  * pwm_init_state(pwm, &state);
221  * pwm_set_relative_duty_cycle(&state, 50, 100);
222  * pwm_apply_state(pwm, &state);
223  *
224  * This functions returns -EINVAL if @duty_cycle and/or @scale are
225  * inconsistent (@scale == 0 or @duty_cycle > @scale).
226  */
227 static inline int
pwm_set_relative_duty_cycle(struct pwm_state * state,unsigned int duty_cycle,unsigned int scale)228 pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
229 			    unsigned int scale)
230 {
231 	if (!scale || duty_cycle > scale)
232 		return -EINVAL;
233 
234 	state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
235 						  state->period,
236 						  scale);
237 
238 	return 0;
239 }
240 
241 /**
242  * struct pwm_ops - PWM controller operations
243  * @request: optional hook for requesting a PWM
244  * @free: optional hook for freeing a PWM
245  * @config: configure duty cycles and period length for this PWM
246  * @set_polarity: configure the polarity of this PWM
247  * @capture: capture and report PWM signal
248  * @enable: enable PWM output toggling
249  * @disable: disable PWM output toggling
250  * @apply: atomically apply a new PWM config. The state argument
251  *	   should be adjusted with the real hardware config (if the
252  *	   approximate the period or duty_cycle value, state should
253  *	   reflect it)
254  * @get_state: get the current PWM state. This function is only
255  *	       called once per PWM device when the PWM chip is
256  *	       registered.
257  * @dbg_show: optional routine to show contents in debugfs
258  * @owner: helps prevent removal of modules exporting active PWMs
259  */
260 struct pwm_ops {
261 	int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
262 	void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
263 	int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
264 		      int duty_ns, int period_ns);
265 	int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
266 			    enum pwm_polarity polarity);
267 	int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
268 		       struct pwm_capture *result, unsigned long timeout);
269 	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
270 	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
271 	int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
272 		     struct pwm_state *state);
273 	void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
274 			  struct pwm_state *state);
275 #ifdef CONFIG_DEBUG_FS
276 	void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);
277 #endif
278 	struct module *owner;
279 };
280 
281 /**
282  * struct pwm_chip - abstract a PWM controller
283  * @dev: device providing the PWMs
284  * @list: list node for internal use
285  * @ops: callbacks for this PWM controller
286  * @base: number of first PWM controlled by this chip
287  * @npwm: number of PWMs controlled by this chip
288  * @pwms: array of PWM devices allocated by the framework
289  * @of_xlate: request a PWM device given a device tree PWM specifier
290  * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
291  */
292 struct pwm_chip {
293 	struct device *dev;
294 	struct list_head list;
295 	const struct pwm_ops *ops;
296 	int base;
297 	unsigned int npwm;
298 
299 	struct pwm_device *pwms;
300 
301 	struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
302 					const struct of_phandle_args *args);
303 	unsigned int of_pwm_n_cells;
304 };
305 
306 /**
307  * struct pwm_capture - PWM capture data
308  * @period: period of the PWM signal (in nanoseconds)
309  * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
310  */
311 struct pwm_capture {
312 	unsigned int period;
313 	unsigned int duty_cycle;
314 };
315 
316 #if IS_ENABLED(CONFIG_PWM)
317 /* PWM user APIs */
318 struct pwm_device *pwm_request(int pwm_id, const char *label);
319 void pwm_free(struct pwm_device *pwm);
320 int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
321 int pwm_adjust_config(struct pwm_device *pwm);
322 
323 /**
324  * pwm_config() - change a PWM device configuration
325  * @pwm: PWM device
326  * @duty_ns: "on" time (in nanoseconds)
327  * @period_ns: duration (in nanoseconds) of one cycle
328  *
329  * Returns: 0 on success or a negative error code on failure.
330  */
pwm_config(struct pwm_device * pwm,int duty_ns,int period_ns)331 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
332 			     int period_ns)
333 {
334 	struct pwm_state state;
335 
336 	if (!pwm)
337 		return -EINVAL;
338 
339 	if (duty_ns < 0 || period_ns < 0)
340 		return -EINVAL;
341 
342 	pwm_get_state(pwm, &state);
343 	if (state.duty_cycle == duty_ns && state.period == period_ns)
344 		return 0;
345 
346 	state.duty_cycle = duty_ns;
347 	state.period = period_ns;
348 	return pwm_apply_state(pwm, &state);
349 }
350 
351 /**
352  * pwm_set_polarity() - configure the polarity of a PWM signal
353  * @pwm: PWM device
354  * @polarity: new polarity of the PWM signal
355  *
356  * Note that the polarity cannot be configured while the PWM device is
357  * enabled.
358  *
359  * Returns: 0 on success or a negative error code on failure.
360  */
pwm_set_polarity(struct pwm_device * pwm,enum pwm_polarity polarity)361 static inline int pwm_set_polarity(struct pwm_device *pwm,
362 				   enum pwm_polarity polarity)
363 {
364 	struct pwm_state state;
365 
366 	if (!pwm)
367 		return -EINVAL;
368 
369 	pwm_get_state(pwm, &state);
370 	if (state.polarity == polarity)
371 		return 0;
372 
373 	/*
374 	 * Changing the polarity of a running PWM without adjusting the
375 	 * dutycycle/period value is a bit risky (can introduce glitches).
376 	 * Return -EBUSY in this case.
377 	 * Note that this is allowed when using pwm_apply_state() because
378 	 * the user specifies all the parameters.
379 	 */
380 	if (state.enabled)
381 		return -EBUSY;
382 
383 	state.polarity = polarity;
384 	return pwm_apply_state(pwm, &state);
385 }
386 
387 /**
388  * pwm_enable() - start a PWM output toggling
389  * @pwm: PWM device
390  *
391  * Returns: 0 on success or a negative error code on failure.
392  */
pwm_enable(struct pwm_device * pwm)393 static inline int pwm_enable(struct pwm_device *pwm)
394 {
395 	struct pwm_state state;
396 
397 	if (!pwm)
398 		return -EINVAL;
399 
400 	pwm_get_state(pwm, &state);
401 	if (state.enabled)
402 		return 0;
403 
404 	state.enabled = true;
405 	return pwm_apply_state(pwm, &state);
406 }
407 
408 /**
409  * pwm_disable() - stop a PWM output toggling
410  * @pwm: PWM device
411  */
pwm_disable(struct pwm_device * pwm)412 static inline void pwm_disable(struct pwm_device *pwm)
413 {
414 	struct pwm_state state;
415 
416 	if (!pwm)
417 		return;
418 
419 	pwm_get_state(pwm, &state);
420 	if (!state.enabled)
421 		return;
422 
423 	state.enabled = false;
424 	pwm_apply_state(pwm, &state);
425 }
426 
427 /* PWM provider APIs */
428 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
429 		unsigned long timeout);
430 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
431 void *pwm_get_chip_data(struct pwm_device *pwm);
432 
433 int pwmchip_add_with_polarity(struct pwm_chip *chip,
434 			      enum pwm_polarity polarity);
435 int pwmchip_add(struct pwm_chip *chip);
436 int pwmchip_remove(struct pwm_chip *chip);
437 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
438 					 unsigned int index,
439 					 const char *label);
440 
441 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
442 		const struct of_phandle_args *args);
443 
444 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
445 struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id);
446 void pwm_put(struct pwm_device *pwm);
447 
448 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
449 struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
450 				   const char *con_id);
451 void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
452 #else
pwm_request(int pwm_id,const char * label)453 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
454 {
455 	return ERR_PTR(-ENODEV);
456 }
457 
pwm_free(struct pwm_device * pwm)458 static inline void pwm_free(struct pwm_device *pwm)
459 {
460 }
461 
pwm_apply_state(struct pwm_device * pwm,const struct pwm_state * state)462 static inline int pwm_apply_state(struct pwm_device *pwm,
463 				  const struct pwm_state *state)
464 {
465 	return -ENOTSUPP;
466 }
467 
pwm_adjust_config(struct pwm_device * pwm)468 static inline int pwm_adjust_config(struct pwm_device *pwm)
469 {
470 	return -ENOTSUPP;
471 }
472 
pwm_config(struct pwm_device * pwm,int duty_ns,int period_ns)473 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
474 			     int period_ns)
475 {
476 	return -EINVAL;
477 }
478 
pwm_capture(struct pwm_device * pwm,struct pwm_capture * result,unsigned long timeout)479 static inline int pwm_capture(struct pwm_device *pwm,
480 			      struct pwm_capture *result,
481 			      unsigned long timeout)
482 {
483 	return -EINVAL;
484 }
485 
pwm_set_polarity(struct pwm_device * pwm,enum pwm_polarity polarity)486 static inline int pwm_set_polarity(struct pwm_device *pwm,
487 				   enum pwm_polarity polarity)
488 {
489 	return -ENOTSUPP;
490 }
491 
pwm_enable(struct pwm_device * pwm)492 static inline int pwm_enable(struct pwm_device *pwm)
493 {
494 	return -EINVAL;
495 }
496 
pwm_disable(struct pwm_device * pwm)497 static inline void pwm_disable(struct pwm_device *pwm)
498 {
499 }
500 
pwm_set_chip_data(struct pwm_device * pwm,void * data)501 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
502 {
503 	return -EINVAL;
504 }
505 
pwm_get_chip_data(struct pwm_device * pwm)506 static inline void *pwm_get_chip_data(struct pwm_device *pwm)
507 {
508 	return NULL;
509 }
510 
pwmchip_add(struct pwm_chip * chip)511 static inline int pwmchip_add(struct pwm_chip *chip)
512 {
513 	return -EINVAL;
514 }
515 
pwmchip_add_inversed(struct pwm_chip * chip)516 static inline int pwmchip_add_inversed(struct pwm_chip *chip)
517 {
518 	return -EINVAL;
519 }
520 
pwmchip_remove(struct pwm_chip * chip)521 static inline int pwmchip_remove(struct pwm_chip *chip)
522 {
523 	return -EINVAL;
524 }
525 
pwm_request_from_chip(struct pwm_chip * chip,unsigned int index,const char * label)526 static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
527 						       unsigned int index,
528 						       const char *label)
529 {
530 	return ERR_PTR(-ENODEV);
531 }
532 
pwm_get(struct device * dev,const char * consumer)533 static inline struct pwm_device *pwm_get(struct device *dev,
534 					 const char *consumer)
535 {
536 	return ERR_PTR(-ENODEV);
537 }
538 
of_pwm_get(struct device_node * np,const char * con_id)539 static inline struct pwm_device *of_pwm_get(struct device_node *np,
540 					    const char *con_id)
541 {
542 	return ERR_PTR(-ENODEV);
543 }
544 
pwm_put(struct pwm_device * pwm)545 static inline void pwm_put(struct pwm_device *pwm)
546 {
547 }
548 
devm_pwm_get(struct device * dev,const char * consumer)549 static inline struct pwm_device *devm_pwm_get(struct device *dev,
550 					      const char *consumer)
551 {
552 	return ERR_PTR(-ENODEV);
553 }
554 
devm_of_pwm_get(struct device * dev,struct device_node * np,const char * con_id)555 static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
556 						 struct device_node *np,
557 						 const char *con_id)
558 {
559 	return ERR_PTR(-ENODEV);
560 }
561 
devm_pwm_put(struct device * dev,struct pwm_device * pwm)562 static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
563 {
564 }
565 #endif
566 
pwm_apply_args(struct pwm_device * pwm)567 static inline void pwm_apply_args(struct pwm_device *pwm)
568 {
569 	struct pwm_state state = { };
570 
571 	/*
572 	 * PWM users calling pwm_apply_args() expect to have a fresh config
573 	 * where the polarity and period are set according to pwm_args info.
574 	 * The problem is, polarity can only be changed when the PWM is
575 	 * disabled.
576 	 *
577 	 * PWM drivers supporting hardware readout may declare the PWM device
578 	 * as enabled, and prevent polarity setting, which changes from the
579 	 * existing behavior, where all PWM devices are declared as disabled
580 	 * at startup (even if they are actually enabled), thus authorizing
581 	 * polarity setting.
582 	 *
583 	 * To fulfill this requirement, we apply a new state which disables
584 	 * the PWM device and set the reference period and polarity config.
585 	 *
586 	 * Note that PWM users requiring a smooth handover between the
587 	 * bootloader and the kernel (like critical regulators controlled by
588 	 * PWM devices) will have to switch to the atomic API and avoid calling
589 	 * pwm_apply_args().
590 	 */
591 
592 	state.enabled = false;
593 	state.polarity = pwm->args.polarity;
594 	state.period = pwm->args.period;
595 
596 	pwm_apply_state(pwm, &state);
597 }
598 
599 struct pwm_lookup {
600 	struct list_head list;
601 	const char *provider;
602 	unsigned int index;
603 	const char *dev_id;
604 	const char *con_id;
605 	unsigned int period;
606 	enum pwm_polarity polarity;
607 	const char *module; /* optional, may be NULL */
608 };
609 
610 #define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id,	\
611 			       _period, _polarity, _module)		\
612 	{								\
613 		.provider = _provider,					\
614 		.index = _index,					\
615 		.dev_id = _dev_id,					\
616 		.con_id = _con_id,					\
617 		.period = _period,					\
618 		.polarity = _polarity,					\
619 		.module = _module,					\
620 	}
621 
622 #define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
623 	PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
624 			       _polarity, NULL)
625 
626 #if IS_ENABLED(CONFIG_PWM)
627 void pwm_add_table(struct pwm_lookup *table, size_t num);
628 void pwm_remove_table(struct pwm_lookup *table, size_t num);
629 #else
pwm_add_table(struct pwm_lookup * table,size_t num)630 static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
631 {
632 }
633 
pwm_remove_table(struct pwm_lookup * table,size_t num)634 static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
635 {
636 }
637 #endif
638 
639 #ifdef CONFIG_PWM_SYSFS
640 void pwmchip_sysfs_export(struct pwm_chip *chip);
641 void pwmchip_sysfs_unexport(struct pwm_chip *chip);
642 #else
pwmchip_sysfs_export(struct pwm_chip * chip)643 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
644 {
645 }
646 
pwmchip_sysfs_unexport(struct pwm_chip * chip)647 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
648 {
649 }
650 #endif /* CONFIG_PWM_SYSFS */
651 
652 #endif /* __LINUX_PWM_H */
653