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TOMOYO Linux Cross Reference
Linux/include/linux/pwm.h

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  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  */
 93 static inline void pwm_get_state(const struct pwm_device *pwm,
 94                                  struct pwm_state *state)
 95 {
 96         *state = pwm->state;
 97 }
 98 
 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 
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 
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 
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 
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 
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 
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  */
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
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
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  */
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  */
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  */
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  */
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
453 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
454 {
455         return ERR_PTR(-ENODEV);
456 }
457 
458 static inline void pwm_free(struct pwm_device *pwm)
459 {
460 }
461 
462 static inline int pwm_apply_state(struct pwm_device *pwm,
463                                   const struct pwm_state *state)
464 {
465         return -ENOTSUPP;
466 }
467 
468 static inline int pwm_adjust_config(struct pwm_device *pwm)
469 {
470         return -ENOTSUPP;
471 }
472 
473 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
474                              int period_ns)
475 {
476         return -EINVAL;
477 }
478 
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 
486 static inline int pwm_set_polarity(struct pwm_device *pwm,
487                                    enum pwm_polarity polarity)
488 {
489         return -ENOTSUPP;
490 }
491 
492 static inline int pwm_enable(struct pwm_device *pwm)
493 {
494         return -EINVAL;
495 }
496 
497 static inline void pwm_disable(struct pwm_device *pwm)
498 {
499 }
500 
501 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
502 {
503         return -EINVAL;
504 }
505 
506 static inline void *pwm_get_chip_data(struct pwm_device *pwm)
507 {
508         return NULL;
509 }
510 
511 static inline int pwmchip_add(struct pwm_chip *chip)
512 {
513         return -EINVAL;
514 }
515 
516 static inline int pwmchip_add_inversed(struct pwm_chip *chip)
517 {
518         return -EINVAL;
519 }
520 
521 static inline int pwmchip_remove(struct pwm_chip *chip)
522 {
523         return -EINVAL;
524 }
525 
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 
533 static inline struct pwm_device *pwm_get(struct device *dev,
534                                          const char *consumer)
535 {
536         return ERR_PTR(-ENODEV);
537 }
538 
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 
545 static inline void pwm_put(struct pwm_device *pwm)
546 {
547 }
548 
549 static inline struct pwm_device *devm_pwm_get(struct device *dev,
550                                               const char *consumer)
551 {
552         return ERR_PTR(-ENODEV);
553 }
554 
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 
562 static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
563 {
564 }
565 #endif
566 
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
630 static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
631 {
632 }
633 
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 void pwmchip_sysfs_unexport_children(struct pwm_chip *chip);
643 #else
644 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
645 {
646 }
647 
648 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
649 {
650 }
651 
652 static inline void pwmchip_sysfs_unexport_children(struct pwm_chip *chip)
653 {
654 }
655 #endif /* CONFIG_PWM_SYSFS */
656 
657 #endif /* __LINUX_PWM_H */
658 

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