root/include/linux/pwm.h

INCLUDED FROM

DEFINITIONS

1. pwm_get_state
2. pwm_is_enabled
3. pwm_set_period
4. pwm_get_period
5. pwm_set_duty_cycle
6. pwm_get_duty_cycle
7. pwm_get_polarity
8. pwm_get_args
9. pwm_init_state
10. pwm_get_relative_duty_cycle
11. pwm_set_relative_duty_cycle
12. pwm_config
13. pwm_enable
14. pwm_disable
15. pwm_request
16. pwm_free
17. pwm_apply_state
18. pwm_adjust_config
19. pwm_config
20. pwm_capture
21. pwm_enable
22. pwm_disable
23. pwm_set_chip_data
24. pwm_get_chip_data
25. pwmchip_add
26. pwmchip_add_inversed
27. pwmchip_remove
28. pwm_request_from_chip
29. pwm_get
30. of_pwm_get
31. pwm_put
32. devm_pwm_get
33. devm_of_pwm_get
34. devm_fwnode_pwm_get
35. devm_pwm_put
36. pwm_apply_args
37. pwm_add_table
38. pwm_remove_table
39. pwmchip_sysfs_export
40. pwmchip_sysfs_unexport

   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  * @capture: capture and report PWM signal
 246  * @apply: atomically apply a new PWM config. The state argument
 247  *         should be adjusted with the real hardware config (if the
 248  *         approximate the period or duty_cycle value, state should
 249  *         reflect it)
 250  * @get_state: get the current PWM state. This function is only
 251  *             called once per PWM device when the PWM chip is
 252  *             registered.
 253  * @owner: helps prevent removal of modules exporting active PWMs
 254  * @config: configure duty cycles and period length for this PWM
 255  * @set_polarity: configure the polarity of this PWM
 256  * @enable: enable PWM output toggling
 257  * @disable: disable PWM output toggling
 258  */
 259 struct pwm_ops {
 260         int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
 261         void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
 262         int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
 263                        struct pwm_capture *result, unsigned long timeout);
 264         int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
 265                      const struct pwm_state *state);
 266         void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
 267                           struct pwm_state *state);
 268         struct module *owner;
 269 
 270         /* Only used by legacy drivers */
 271         int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
 272                       int duty_ns, int period_ns);
 273         int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
 274                             enum pwm_polarity polarity);
 275         int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
 276         void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
 277 };
 278 
 279 /**
 280  * struct pwm_chip - abstract a PWM controller
 281  * @dev: device providing the PWMs
 282  * @ops: callbacks for this PWM controller
 283  * @base: number of first PWM controlled by this chip
 284  * @npwm: number of PWMs controlled by this chip
 285  * @of_xlate: request a PWM device given a device tree PWM specifier
 286  * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
 287  * @list: list node for internal use
 288  * @pwms: array of PWM devices allocated by the framework
 289  */
 290 struct pwm_chip {
 291         struct device *dev;
 292         const struct pwm_ops *ops;
 293         int base;
 294         unsigned int npwm;
 295 
 296         struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
 297                                         const struct of_phandle_args *args);
 298         unsigned int of_pwm_n_cells;
 299 
 300         /* only used internally by the PWM framework */
 301         struct list_head list;
 302         struct pwm_device *pwms;
 303 };
 304 
 305 /**
 306  * struct pwm_capture - PWM capture data
 307  * @period: period of the PWM signal (in nanoseconds)
 308  * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
 309  */
 310 struct pwm_capture {
 311         unsigned int period;
 312         unsigned int duty_cycle;
 313 };
 314 
 315 #if IS_ENABLED(CONFIG_PWM)
 316 /* PWM user APIs */
 317 struct pwm_device *pwm_request(int pwm_id, const char *label);
 318 void pwm_free(struct pwm_device *pwm);
 319 int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state);
 320 int pwm_adjust_config(struct pwm_device *pwm);
 321 
 322 /**
 323  * pwm_config() - change a PWM device configuration
 324  * @pwm: PWM device
 325  * @duty_ns: "on" time (in nanoseconds)
 326  * @period_ns: duration (in nanoseconds) of one cycle
 327  *
 328  * Returns: 0 on success or a negative error code on failure.
 329  */
 330 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 331                              int period_ns)
 332 {
 333         struct pwm_state state;
 334 
 335         if (!pwm)
 336                 return -EINVAL;
 337 
 338         if (duty_ns < 0 || period_ns < 0)
 339                 return -EINVAL;
 340 
 341         pwm_get_state(pwm, &state);
 342         if (state.duty_cycle == duty_ns && state.period == period_ns)
 343                 return 0;
 344 
 345         state.duty_cycle = duty_ns;
 346         state.period = period_ns;
 347         return pwm_apply_state(pwm, &state);
 348 }
 349 
 350 /**
 351  * pwm_enable() - start a PWM output toggling
 352  * @pwm: PWM device
 353  *
 354  * Returns: 0 on success or a negative error code on failure.
 355  */
 356 static inline int pwm_enable(struct pwm_device *pwm)
 357 {
 358         struct pwm_state state;
 359 
 360         if (!pwm)
 361                 return -EINVAL;
 362 
 363         pwm_get_state(pwm, &state);
 364         if (state.enabled)
 365                 return 0;
 366 
 367         state.enabled = true;
 368         return pwm_apply_state(pwm, &state);
 369 }
 370 
 371 /**
 372  * pwm_disable() - stop a PWM output toggling
 373  * @pwm: PWM device
 374  */
 375 static inline void pwm_disable(struct pwm_device *pwm)
 376 {
 377         struct pwm_state state;
 378 
 379         if (!pwm)
 380                 return;
 381 
 382         pwm_get_state(pwm, &state);
 383         if (!state.enabled)
 384                 return;
 385 
 386         state.enabled = false;
 387         pwm_apply_state(pwm, &state);
 388 }
 389 
 390 /* PWM provider APIs */
 391 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
 392                 unsigned long timeout);
 393 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 394 void *pwm_get_chip_data(struct pwm_device *pwm);
 395 
 396 int pwmchip_add_with_polarity(struct pwm_chip *chip,
 397                               enum pwm_polarity polarity);
 398 int pwmchip_add(struct pwm_chip *chip);
 399 int pwmchip_remove(struct pwm_chip *chip);
 400 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 401                                          unsigned int index,
 402                                          const char *label);
 403 
 404 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
 405                 const struct of_phandle_args *args);
 406 
 407 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
 408 struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,
 409                               const char *con_id);
 410 void pwm_put(struct pwm_device *pwm);
 411 
 412 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
 413 struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
 414                                    const char *con_id);
 415 struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
 416                                        struct fwnode_handle *fwnode,
 417                                        const char *con_id);
 418 void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
 419 #else
 420 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
 421 {
 422         return ERR_PTR(-ENODEV);
 423 }
 424 
 425 static inline void pwm_free(struct pwm_device *pwm)
 426 {
 427 }
 428 
 429 static inline int pwm_apply_state(struct pwm_device *pwm,
 430                                   const struct pwm_state *state)
 431 {
 432         return -ENOTSUPP;
 433 }
 434 
 435 static inline int pwm_adjust_config(struct pwm_device *pwm)
 436 {
 437         return -ENOTSUPP;
 438 }
 439 
 440 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 441                              int period_ns)
 442 {
 443         return -EINVAL;
 444 }
 445 
 446 static inline int pwm_capture(struct pwm_device *pwm,
 447                               struct pwm_capture *result,
 448                               unsigned long timeout)
 449 {
 450         return -EINVAL;
 451 }
 452 
 453 static inline int pwm_enable(struct pwm_device *pwm)
 454 {
 455         return -EINVAL;
 456 }
 457 
 458 static inline void pwm_disable(struct pwm_device *pwm)
 459 {
 460 }
 461 
 462 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 463 {
 464         return -EINVAL;
 465 }
 466 
 467 static inline void *pwm_get_chip_data(struct pwm_device *pwm)
 468 {
 469         return NULL;
 470 }
 471 
 472 static inline int pwmchip_add(struct pwm_chip *chip)
 473 {
 474         return -EINVAL;
 475 }
 476 
 477 static inline int pwmchip_add_inversed(struct pwm_chip *chip)
 478 {
 479         return -EINVAL;
 480 }
 481 
 482 static inline int pwmchip_remove(struct pwm_chip *chip)
 483 {
 484         return -EINVAL;
 485 }
 486 
 487 static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 488                                                        unsigned int index,
 489                                                        const char *label)
 490 {
 491         return ERR_PTR(-ENODEV);
 492 }
 493 
 494 static inline struct pwm_device *pwm_get(struct device *dev,
 495                                          const char *consumer)
 496 {
 497         return ERR_PTR(-ENODEV);
 498 }
 499 
 500 static inline struct pwm_device *of_pwm_get(struct device *dev,
 501                                             struct device_node *np,
 502                                             const char *con_id)
 503 {
 504         return ERR_PTR(-ENODEV);
 505 }
 506 
 507 static inline void pwm_put(struct pwm_device *pwm)
 508 {
 509 }
 510 
 511 static inline struct pwm_device *devm_pwm_get(struct device *dev,
 512                                               const char *consumer)
 513 {
 514         return ERR_PTR(-ENODEV);
 515 }
 516 
 517 static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
 518                                                  struct device_node *np,
 519                                                  const char *con_id)
 520 {
 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         return ERR_PTR(-ENODEV);
 529 }
 530 
 531 static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
 532 {
 533 }
 534 #endif
 535 
 536 static inline void pwm_apply_args(struct pwm_device *pwm)
 537 {
 538         struct pwm_state state = { };
 539 
 540         /*
 541          * PWM users calling pwm_apply_args() expect to have a fresh config
 542          * where the polarity and period are set according to pwm_args info.
 543          * The problem is, polarity can only be changed when the PWM is
 544          * disabled.
 545          *
 546          * PWM drivers supporting hardware readout may declare the PWM device
 547          * as enabled, and prevent polarity setting, which changes from the
 548          * existing behavior, where all PWM devices are declared as disabled
 549          * at startup (even if they are actually enabled), thus authorizing
 550          * polarity setting.
 551          *
 552          * To fulfill this requirement, we apply a new state which disables
 553          * the PWM device and set the reference period and polarity config.
 554          *
 555          * Note that PWM users requiring a smooth handover between the
 556          * bootloader and the kernel (like critical regulators controlled by
 557          * PWM devices) will have to switch to the atomic API and avoid calling
 558          * pwm_apply_args().
 559          */
 560 
 561         state.enabled = false;
 562         state.polarity = pwm->args.polarity;
 563         state.period = pwm->args.period;
 564 
 565         pwm_apply_state(pwm, &state);
 566 }
 567 
 568 struct pwm_lookup {
 569         struct list_head list;
 570         const char *provider;
 571         unsigned int index;
 572         const char *dev_id;
 573         const char *con_id;
 574         unsigned int period;
 575         enum pwm_polarity polarity;
 576         const char *module; /* optional, may be NULL */
 577 };
 578 
 579 #define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id,     \
 580                                _period, _polarity, _module)             \
 581         {                                                               \
 582                 .provider = _provider,                                  \
 583                 .index = _index,                                        \
 584                 .dev_id = _dev_id,                                      \
 585                 .con_id = _con_id,                                      \
 586                 .period = _period,                                      \
 587                 .polarity = _polarity,                                  \
 588                 .module = _module,                                      \
 589         }
 590 
 591 #define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
 592         PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
 593                                _polarity, NULL)
 594 
 595 #if IS_ENABLED(CONFIG_PWM)
 596 void pwm_add_table(struct pwm_lookup *table, size_t num);
 597 void pwm_remove_table(struct pwm_lookup *table, size_t num);
 598 #else
 599 static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
 600 {
 601 }
 602 
 603 static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
 604 {
 605 }
 606 #endif
 607 
 608 #ifdef CONFIG_PWM_SYSFS
 609 void pwmchip_sysfs_export(struct pwm_chip *chip);
 610 void pwmchip_sysfs_unexport(struct pwm_chip *chip);
 611 #else
 612 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
 613 {
 614 }
 615 
 616 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
 617 {
 618 }
 619 #endif /* CONFIG_PWM_SYSFS */
 620 
 621 #endif /* __LINUX_PWM_H */