include/linux/pwm.h

   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 */