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         u64 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         u64 period;
  60         u64 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: last applied state
  75  * @last: last implemented state (for PWM_DEBUG)
  76  */
  77 struct pwm_device {
  78         const char *label;
  79         unsigned long flags;
  80         unsigned int hwpwm;
  81         unsigned int pwm;
  82         struct pwm_chip *chip;
  83         void *chip_data;
  84
  85         struct pwm_args args;
  86         struct pwm_state state;
  87         struct pwm_state last;
  88 };
  89
  90 /**
  91  * pwm_get_state() - retrieve the current PWM state
  92  * @pwm: PWM device
  93  * @state: state to fill with the current PWM state
  94  *
  95  * The returned PWM state represents the state that was applied by a previous call to
  96  * pwm_apply_state(). Drivers may have to slightly tweak that state before programming it to
  97  * hardware. If pwm_apply_state() was never called, this returns either the current hardware
  98  * state (if supported) or the default settings.
  99  */
 100 static inline void pwm_get_state(const struct pwm_device *pwm,
 101                                  struct pwm_state *state)
 102 {
 103         *state = pwm->state;
 104 }
 105
 106 static inline bool pwm_is_enabled(const struct pwm_device *pwm)
 107 {
 108         struct pwm_state state;
 109
 110         pwm_get_state(pwm, &state);
 111
 112         return state.enabled;
 113 }
 114
 115 static inline void pwm_set_period(struct pwm_device *pwm, u64 period)
 116 {
 117         if (pwm)
 118                 pwm->state.period = period;
 119 }
 120
 121 static inline u64 pwm_get_period(const struct pwm_device *pwm)
 122 {
 123         struct pwm_state state;
 124
 125         pwm_get_state(pwm, &state);
 126
 127         return state.period;
 128 }
 129
 130 static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
 131 {
 132         if (pwm)
 133                 pwm->state.duty_cycle = duty;
 134 }
 135
 136 static inline u64 pwm_get_duty_cycle(const struct pwm_device *pwm)
 137 {
 138         struct pwm_state state;
 139
 140         pwm_get_state(pwm, &state);
 141
 142         return state.duty_cycle;
 143 }
 144
 145 static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
 146 {
 147         struct pwm_state state;
 148
 149         pwm_get_state(pwm, &state);
 150
 151         return state.polarity;
 152 }
 153
 154 static inline void pwm_get_args(const struct pwm_device *pwm,
 155                                 struct pwm_args *args)
 156 {
 157         *args = pwm->args;
 158 }
 159
 160 /**
 161  * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
 162  * @pwm: PWM device
 163  * @state: state to fill with the prepared PWM state
 164  *
 165  * This functions prepares a state that can later be tweaked and applied
 166  * to the PWM device with pwm_apply_state(). This is a convenient function
 167  * that first retrieves the current PWM state and the replaces the period
 168  * and polarity fields with the reference values defined in pwm->args.
 169  * Once the function returns, you can adjust the ->enabled and ->duty_cycle
 170  * fields according to your needs before calling pwm_apply_state().
 171  *
 172  * ->duty_cycle is initially set to zero to avoid cases where the current
 173  * ->duty_cycle value exceed the pwm_args->period one, which would trigger
 174  * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
 175  * first.
 176  */
 177 static inline void pwm_init_state(const struct pwm_device *pwm,
 178                                   struct pwm_state *state)
 179 {
 180         struct pwm_args args;
 181
 182         /* First get the current state. */
 183         pwm_get_state(pwm, state);
 184
 185         /* Then fill it with the reference config */
 186         pwm_get_args(pwm, &args);
 187
 188         state->period = args.period;
 189         state->polarity = args.polarity;
 190         state->duty_cycle = 0;
 191 }
 192
 193 /**
 194  * pwm_get_relative_duty_cycle() - Get a relative duty cycle value
 195  * @state: PWM state to extract the duty cycle from
 196  * @scale: target scale of the relative duty cycle
 197  *
 198  * This functions converts the absolute duty cycle stored in @state (expressed
 199  * in nanosecond) into a value relative to the period.
 200  *
 201  * For example if you want to get the duty_cycle expressed in percent, call:
 202  *
 203  * pwm_get_state(pwm, &state);
 204  * duty = pwm_get_relative_duty_cycle(&state, 100);
 205  */
 206 static inline unsigned int
 207 pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
 208 {
 209         if (!state->period)
 210                 return 0;
 211
 212         return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
 213                                      state->period);
 214 }
 215
 216 /**
 217  * pwm_set_relative_duty_cycle() - Set a relative duty cycle value
 218  * @state: PWM state to fill
 219  * @duty_cycle: relative duty cycle value
 220  * @scale: scale in which @duty_cycle is expressed
 221  *
 222  * This functions converts a relative into an absolute duty cycle (expressed
 223  * in nanoseconds), and puts the result in state->duty_cycle.
 224  *
 225  * For example if you want to configure a 50% duty cycle, call:
 226  *
 227  * pwm_init_state(pwm, &state);
 228  * pwm_set_relative_duty_cycle(&state, 50, 100);
 229  * pwm_apply_state(pwm, &state);
 230  *
 231  * This functions returns -EINVAL if @duty_cycle and/or @scale are
 232  * inconsistent (@scale == 0 or @duty_cycle > @scale).
 233  */
 234 static inline int
 235 pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
 236                             unsigned int scale)
 237 {
 238         if (!scale || duty_cycle > scale)
 239                 return -EINVAL;
 240
 241         state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
 242                                                   state->period,
 243                                                   scale);
 244
 245         return 0;
 246 }
 247
 248 /**
 249  * struct pwm_ops - PWM controller operations
 250  * @request: optional hook for requesting a PWM
 251  * @free: optional hook for freeing a PWM
 252  * @capture: capture and report PWM signal
 253  * @apply: atomically apply a new PWM config
 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  * @owner: helps prevent removal of modules exporting active PWMs
 258  * @config: configure duty cycles and period length for this PWM
 259  * @set_polarity: configure the polarity of this PWM
 260  * @enable: enable PWM output toggling
 261  * @disable: disable PWM output toggling
 262  */
 263 struct pwm_ops {
 264         int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
 265         void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
 266         int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
 267                        struct pwm_capture *result, unsigned long timeout);
 268         int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
 269                      const struct pwm_state *state);
 270         void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
 271                           struct pwm_state *state);
 272         struct module *owner;
 273
 274         /* Only used by legacy drivers */
 275         int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
 276                       int duty_ns, int period_ns);
 277         int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
 278                             enum pwm_polarity polarity);
 279         int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
 280         void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
 281 };
 282
 283 /**
 284  * struct pwm_chip - abstract a PWM controller
 285  * @dev: device providing the PWMs
 286  * @ops: callbacks for this PWM controller
 287  * @base: number of first PWM controlled by this chip
 288  * @npwm: number of PWMs controlled by this chip
 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  * @list: list node for internal use
 292  * @pwms: array of PWM devices allocated by the framework
 293  */
 294 struct pwm_chip {
 295         struct device *dev;
 296         const struct pwm_ops *ops;
 297         int base;
 298         unsigned int npwm;
 299
 300         struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
 301                                         const struct of_phandle_args *args);
 302         unsigned int of_pwm_n_cells;
 303
 304         /* only used internally by the PWM framework */
 305         struct list_head list;
 306         struct pwm_device *pwms;
 307 };
 308
 309 /**
 310  * struct pwm_capture - PWM capture data
 311  * @period: period of the PWM signal (in nanoseconds)
 312  * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
 313  */
 314 struct pwm_capture {
 315         unsigned int period;
 316         unsigned int duty_cycle;
 317 };
 318
 319 #if IS_ENABLED(CONFIG_PWM)
 320 /* PWM user APIs */
 321 struct pwm_device *pwm_request(int pwm_id, const char *label);
 322 void pwm_free(struct pwm_device *pwm);
 323 int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state);
 324 int pwm_adjust_config(struct pwm_device *pwm);
 325
 326 /**
 327  * pwm_config() - change a PWM device configuration
 328  * @pwm: PWM device
 329  * @duty_ns: "on" time (in nanoseconds)
 330  * @period_ns: duration (in nanoseconds) of one cycle
 331  *
 332  * Returns: 0 on success or a negative error code on failure.
 333  */
 334 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 335                              int period_ns)
 336 {
 337         struct pwm_state state;
 338
 339         if (!pwm)
 340                 return -EINVAL;
 341
 342         if (duty_ns < 0 || period_ns < 0)
 343                 return -EINVAL;
 344
 345         pwm_get_state(pwm, &state);
 346         if (state.duty_cycle == duty_ns && state.period == period_ns)
 347                 return 0;
 348
 349         state.duty_cycle = duty_ns;
 350         state.period = period_ns;
 351         return pwm_apply_state(pwm, &state);
 352 }
 353
 354 /**
 355  * pwm_enable() - start a PWM output toggling
 356  * @pwm: PWM device
 357  *
 358  * Returns: 0 on success or a negative error code on failure.
 359  */
 360 static inline int pwm_enable(struct pwm_device *pwm)
 361 {
 362         struct pwm_state state;
 363
 364         if (!pwm)
 365                 return -EINVAL;
 366
 367         pwm_get_state(pwm, &state);
 368         if (state.enabled)
 369                 return 0;
 370
 371         state.enabled = true;
 372         return pwm_apply_state(pwm, &state);
 373 }
 374
 375 /**
 376  * pwm_disable() - stop a PWM output toggling
 377  * @pwm: PWM device
 378  */
 379 static inline void pwm_disable(struct pwm_device *pwm)
 380 {
 381         struct pwm_state state;
 382
 383         if (!pwm)
 384                 return;
 385
 386         pwm_get_state(pwm, &state);
 387         if (!state.enabled)
 388                 return;
 389
 390         state.enabled = false;
 391         pwm_apply_state(pwm, &state);
 392 }
 393
 394 /* PWM provider APIs */
 395 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
 396                 unsigned long timeout);
 397 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 398 void *pwm_get_chip_data(struct pwm_device *pwm);
 399
 400 int pwmchip_add(struct pwm_chip *chip);
 401 int pwmchip_remove(struct pwm_chip *chip);
 402 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 403                                          unsigned int index,
 404                                          const char *label);
 405
 406 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
 407                 const struct of_phandle_args *args);
 408
 409 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
 410 struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,
 411                               const char *con_id);
 412 void pwm_put(struct pwm_device *pwm);
 413
 414 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
 415 struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
 416                                    const char *con_id);
 417 struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
 418                                        struct fwnode_handle *fwnode,
 419                                        const char *con_id);
 420 void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
 421 #else
 422 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
 423 {
 424         return ERR_PTR(-ENODEV);
 425 }
 426
 427 static inline void pwm_free(struct pwm_device *pwm)
 428 {
 429 }
 430
 431 static inline int pwm_apply_state(struct pwm_device *pwm,
 432                                   const struct pwm_state *state)
 433 {
 434         return -ENOTSUPP;
 435 }
 436
 437 static inline int pwm_adjust_config(struct pwm_device *pwm)
 438 {
 439         return -ENOTSUPP;
 440 }
 441
 442 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 443                              int period_ns)
 444 {
 445         return -EINVAL;
 446 }
 447
 448 static inline int pwm_capture(struct pwm_device *pwm,
 449                               struct pwm_capture *result,
 450                               unsigned long timeout)
 451 {
 452         return -EINVAL;
 453 }
 454
 455 static inline int pwm_enable(struct pwm_device *pwm)
 456 {
 457         return -EINVAL;
 458 }
 459
 460 static inline void pwm_disable(struct pwm_device *pwm)
 461 {
 462 }
 463
 464 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 465 {
 466         return -EINVAL;
 467 }
 468
 469 static inline void *pwm_get_chip_data(struct pwm_device *pwm)
 470 {
 471         return NULL;
 472 }
 473
 474 static inline int pwmchip_add(struct pwm_chip *chip)
 475 {
 476         return -EINVAL;
 477 }
 478
 479 static inline int pwmchip_remove(struct pwm_chip *chip)
 480 {
 481         return -EINVAL;
 482 }
 483
 484 static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 485                                                        unsigned int index,
 486                                                        const char *label)
 487 {
 488         return ERR_PTR(-ENODEV);
 489 }
 490
 491 static inline struct pwm_device *pwm_get(struct device *dev,
 492                                          const char *consumer)
 493 {
 494         return ERR_PTR(-ENODEV);
 495 }
 496
 497 static inline struct pwm_device *of_pwm_get(struct device *dev,
 498                                             struct device_node *np,
 499                                             const char *con_id)
 500 {
 501         return ERR_PTR(-ENODEV);
 502 }
 503
 504 static inline void pwm_put(struct pwm_device *pwm)
 505 {
 506 }
 507
 508 static inline struct pwm_device *devm_pwm_get(struct device *dev,
 509                                               const char *consumer)
 510 {
 511         return ERR_PTR(-ENODEV);
 512 }
 513
 514 static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
 515                                                  struct device_node *np,
 516                                                  const char *con_id)
 517 {
 518         return ERR_PTR(-ENODEV);
 519 }
 520
 521 static inline struct pwm_device *
 522 devm_fwnode_pwm_get(struct device *dev, struct fwnode_handle *fwnode,
 523                     const char *con_id)
 524 {
 525         return ERR_PTR(-ENODEV);
 526 }
 527
 528 static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
 529 {
 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
 562         pwm_apply_state(pwm, &state);
 563 }
 564
 565 struct pwm_lookup {
 566         struct list_head list;
 567         const char *provider;
 568         unsigned int index;
 569         const char *dev_id;
 570         const char *con_id;
 571         unsigned int period;
 572         enum pwm_polarity polarity;
 573         const char *module; /* optional, may be NULL */
 574 };
 575
 576 #define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id,     \
 577                                _period, _polarity, _module)             \
 578         {                                                               \
 579                 .provider = _provider,                                  \
 580                 .index = _index,                                        \
 581                 .dev_id = _dev_id,                                      \
 582                 .con_id = _con_id,                                      \
 583                 .period = _period,                                      \
 584                 .polarity = _polarity,                                  \
 585                 .module = _module,                                      \
 586         }
 587
 588 #define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
 589         PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
 590                                _polarity, NULL)
 591
 592 #if IS_ENABLED(CONFIG_PWM)
 593 void pwm_add_table(struct pwm_lookup *table, size_t num);
 594 void pwm_remove_table(struct pwm_lookup *table, size_t num);
 595 #else
 596 static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
 597 {
 598 }
 599
 600 static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
 601 {
 602 }
 603 #endif
 604
 605 #ifdef CONFIG_PWM_SYSFS
 606 void pwmchip_sysfs_export(struct pwm_chip *chip);
 607 void pwmchip_sysfs_unexport(struct pwm_chip *chip);
 608 #else
 609 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
 610 {
 611 }
 612
 613 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
 614 {
 615 }
 616 #endif /* CONFIG_PWM_SYSFS */
 617
 618 #endif /* __LINUX_PWM_H */