include/linux/pwm.h

   1 #ifndef __LINUX_PWM_H
   2 #define __LINUX_PWM_H
   3
   4 #include <linux/err.h>
   5 #include <linux/mutex.h>
   6 #include <linux/of.h>
   7
   8 struct pwm_capture;
   9 struct seq_file;
  10
  11 struct pwm_chip;
  12
  13 /**
  14  * enum pwm_polarity - polarity of a PWM signal
  15  * @PWM_POLARITY_NORMAL: a high signal for the duration of the duty-
  16  * cycle, followed by a low signal for the remainder of the pulse
  17  * period
  18  * @PWM_POLARITY_INVERSED: a low signal for the duration of the duty-
  19  * cycle, followed by a high signal for the remainder of the pulse
  20  * period
  21  */
  22 enum pwm_polarity {
  23         PWM_POLARITY_NORMAL,
  24         PWM_POLARITY_INVERSED,
  25 };
  26
  27 /**
  28  * struct pwm_args - board-dependent PWM arguments
  29  * @period: reference period
  30  * @polarity: reference polarity
  31  *
  32  * This structure describes board-dependent arguments attached to a PWM
  33  * device. These arguments are usually retrieved from the PWM lookup table or
  34  * device tree.
  35  *
  36  * Do not confuse this with the PWM state: PWM arguments represent the initial
  37  * configuration that users want to use on this PWM device rather than the
  38  * current PWM hardware state.
  39  */
  40 struct pwm_args {
  41         unsigned int period;
  42         enum pwm_polarity polarity;
  43 };
  44
  45 enum {
  46         PWMF_REQUESTED = 1 << 0,
  47         PWMF_EXPORTED = 1 << 1,
  48 };
  49
  50 /*
  51  * struct pwm_state - state of a PWM channel
  52  * @period: PWM period (in nanoseconds)
  53  * @duty_cycle: PWM duty cycle (in nanoseconds)
  54  * @polarity: PWM polarity
  55  * @enabled: PWM enabled status
  56  */
  57 struct pwm_state {
  58         unsigned int period;
  59         unsigned int duty_cycle;
  60         enum pwm_polarity polarity;
  61         bool enabled;
  62 };
  63
  64 /**
  65  * struct pwm_device - PWM channel object
  66  * @label: name of the PWM device
  67  * @flags: flags associated with the PWM device
  68  * @hwpwm: per-chip relative index of the PWM device
  69  * @pwm: global index of the PWM device
  70  * @chip: PWM chip providing this PWM device
  71  * @chip_data: chip-private data associated with the PWM device
  72  * @args: PWM arguments
  73  * @state: curent PWM channel state
  74  */
  75 struct pwm_device {
  76         const char *label;
  77         unsigned long flags;
  78         unsigned int hwpwm;
  79         unsigned int pwm;
  80         struct pwm_chip *chip;
  81         void *chip_data;
  82
  83         struct pwm_args args;
  84         struct pwm_state state;
  85 };
  86
  87 /**
  88  * pwm_get_state() - retrieve the current PWM state
  89  * @pwm: PWM device
  90  * @state: state to fill with the current PWM state
  91  */
  92 static inline void pwm_get_state(const struct pwm_device *pwm,
  93                                  struct pwm_state *state)
  94 {
  95         *state = pwm->state;
  96 }
  97
  98 static inline bool pwm_is_enabled(const struct pwm_device *pwm)
  99 {
 100         struct pwm_state state;
 101
 102         pwm_get_state(pwm, &state);
 103
 104         return state.enabled;
 105 }
 106
 107 static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
 108 {
 109         if (pwm)
 110                 pwm->state.period = period;
 111 }
 112
 113 static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
 114 {
 115         struct pwm_state state;
 116
 117         pwm_get_state(pwm, &state);
 118
 119         return state.period;
 120 }
 121
 122 static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
 123 {
 124         if (pwm)
 125                 pwm->state.duty_cycle = duty;
 126 }
 127
 128 static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
 129 {
 130         struct pwm_state state;
 131
 132         pwm_get_state(pwm, &state);
 133
 134         return state.duty_cycle;
 135 }
 136
 137 static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
 138 {
 139         struct pwm_state state;
 140
 141         pwm_get_state(pwm, &state);
 142
 143         return state.polarity;
 144 }
 145
 146 static inline void pwm_get_args(const struct pwm_device *pwm,
 147                                 struct pwm_args *args)
 148 {
 149         *args = pwm->args;
 150 }
 151
 152 /**
 153  * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
 154  * @pwm: PWM device
 155  * @state: state to fill with the prepared PWM state
 156  *
 157  * This functions prepares a state that can later be tweaked and applied
 158  * to the PWM device with pwm_apply_state(). This is a convenient function
 159  * that first retrieves the current PWM state and the replaces the period
 160  * and polarity fields with the reference values defined in pwm->args.
 161  * Once the function returns, you can adjust the ->enabled and ->duty_cycle
 162  * fields according to your needs before calling pwm_apply_state().
 163  *
 164  * ->duty_cycle is initially set to zero to avoid cases where the current
 165  * ->duty_cycle value exceed the pwm_args->period one, which would trigger
 166  * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
 167  * first.
 168  */
 169 static inline void pwm_init_state(const struct pwm_device *pwm,
 170                                   struct pwm_state *state)
 171 {
 172         struct pwm_args args;
 173
 174         /* First get the current state. */
 175         pwm_get_state(pwm, state);
 176
 177         /* Then fill it with the reference config */
 178         pwm_get_args(pwm, &args);
 179
 180         state->period = args.period;
 181         state->polarity = args.polarity;
 182         state->duty_cycle = 0;
 183 }
 184
 185 /**
 186  * pwm_get_relative_duty_cycle() - Get a relative duty cycle value
 187  * @state: PWM state to extract the duty cycle from
 188  * @scale: target scale of the relative duty cycle
 189  *
 190  * This functions converts the absolute duty cycle stored in @state (expressed
 191  * in nanosecond) into a value relative to the period.
 192  *
 193  * For example if you want to get the duty_cycle expressed in percent, call:
 194  *
 195  * pwm_get_state(pwm, &state);
 196  * duty = pwm_get_relative_duty_cycle(&state, 100);
 197  */
 198 static inline unsigned int
 199 pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
 200 {
 201         if (!state->period)
 202                 return 0;
 203
 204         return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
 205                                      state->period);
 206 }
 207
 208 /**
 209  * pwm_set_relative_duty_cycle() - Set a relative duty cycle value
 210  * @state: PWM state to fill
 211  * @duty_cycle: relative duty cycle value
 212  * @scale: scale in which @duty_cycle is expressed
 213  *
 214  * This functions converts a relative into an absolute duty cycle (expressed
 215  * in nanoseconds), and puts the result in state->duty_cycle.
 216  *
 217  * For example if you want to configure a 50% duty cycle, call:
 218  *
 219  * pwm_init_state(pwm, &state);
 220  * pwm_set_relative_duty_cycle(&state, 50, 100);
 221  * pwm_apply_state(pwm, &state);
 222  *
 223  * This functions returns -EINVAL if @duty_cycle and/or @scale are
 224  * inconsistent (@scale == 0 or @duty_cycle > @scale).
 225  */
 226 static inline int
 227 pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
 228                             unsigned int scale)
 229 {
 230         if (!scale || duty_cycle > scale)
 231                 return -EINVAL;
 232
 233         state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
 234                                                   state->period,
 235                                                   scale);
 236
 237         return 0;
 238 }
 239
 240 /**
 241  * struct pwm_ops - PWM controller operations
 242  * @request: optional hook for requesting a PWM
 243  * @free: optional hook for freeing a PWM
 244  * @config: configure duty cycles and period length for this PWM
 245  * @set_polarity: configure the polarity of this PWM
 246  * @capture: capture and report PWM signal
 247  * @enable: enable PWM output toggling
 248  * @disable: disable PWM output toggling
 249  * @apply: atomically apply a new PWM config. The state argument
 250  *         should be adjusted with the real hardware config (if the
 251  *         approximate the period or duty_cycle value, state should
 252  *         reflect it)
 253  * @get_state: get the current PWM state. This function is only
 254  *             called once per PWM device when the PWM chip is
 255  *             registered.
 256  * @dbg_show: optional routine to show contents in debugfs
 257  * @owner: helps prevent removal of modules exporting active PWMs
 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 (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
 263                       int duty_ns, int period_ns);
 264         int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
 265                             enum pwm_polarity polarity);
 266         int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
 267                        struct pwm_capture *result, unsigned long timeout);
 268         int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
 269         void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
 270         int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
 271                      struct pwm_state *state);
 272         void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
 273                           struct pwm_state *state);
 274 #ifdef CONFIG_DEBUG_FS
 275         void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);
 276 #endif
 277         struct module *owner;
 278 };
 279
 280 /**
 281  * struct pwm_chip - abstract a PWM controller
 282  * @dev: device providing the PWMs
 283  * @list: list node for internal use
 284  * @ops: callbacks for this PWM controller
 285  * @base: number of first PWM controlled by this chip
 286  * @npwm: number of PWMs controlled by this chip
 287  * @pwms: array of PWM devices allocated by the framework
 288  * @of_xlate: request a PWM device given a device tree PWM specifier
 289  * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
 290  */
 291 struct pwm_chip {
 292         struct device *dev;
 293         struct list_head list;
 294         const struct pwm_ops *ops;
 295         int base;
 296         unsigned int npwm;
 297
 298         struct pwm_device *pwms;
 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
 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, 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_set_polarity() - configure the polarity of a PWM signal
 352  * @pwm: PWM device
 353  * @polarity: new polarity of the PWM signal
 354  *
 355  * Note that the polarity cannot be configured while the PWM device is
 356  * enabled.
 357  *
 358  * Returns: 0 on success or a negative error code on failure.
 359  */
 360 static inline int pwm_set_polarity(struct pwm_device *pwm,
 361                                    enum pwm_polarity polarity)
 362 {
 363         struct pwm_state state;
 364
 365         if (!pwm)
 366                 return -EINVAL;
 367
 368         pwm_get_state(pwm, &state);
 369         if (state.polarity == polarity)
 370                 return 0;
 371
 372         /*
 373          * Changing the polarity of a running PWM without adjusting the
 374          * dutycycle/period value is a bit risky (can introduce glitches).
 375          * Return -EBUSY in this case.
 376          * Note that this is allowed when using pwm_apply_state() because
 377          * the user specifies all the parameters.
 378          */
 379         if (state.enabled)
 380                 return -EBUSY;
 381
 382         state.polarity = polarity;
 383         return pwm_apply_state(pwm, &state);
 384 }
 385
 386 /**
 387  * pwm_enable() - start a PWM output toggling
 388  * @pwm: PWM device
 389  *
 390  * Returns: 0 on success or a negative error code on failure.
 391  */
 392 static inline int pwm_enable(struct pwm_device *pwm)
 393 {
 394         struct pwm_state state;
 395
 396         if (!pwm)
 397                 return -EINVAL;
 398
 399         pwm_get_state(pwm, &state);
 400         if (state.enabled)
 401                 return 0;
 402
 403         state.enabled = true;
 404         return pwm_apply_state(pwm, &state);
 405 }
 406
 407 /**
 408  * pwm_disable() - stop a PWM output toggling
 409  * @pwm: PWM device
 410  */
 411 static inline void pwm_disable(struct pwm_device *pwm)
 412 {
 413         struct pwm_state state;
 414
 415         if (!pwm)
 416                 return;
 417
 418         pwm_get_state(pwm, &state);
 419         if (!state.enabled)
 420                 return;
 421
 422         state.enabled = false;
 423         pwm_apply_state(pwm, &state);
 424 }
 425
 426 /* PWM provider APIs */
 427 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
 428                 unsigned long timeout);
 429 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 430 void *pwm_get_chip_data(struct pwm_device *pwm);
 431
 432 int pwmchip_add_with_polarity(struct pwm_chip *chip,
 433                               enum pwm_polarity polarity);
 434 int pwmchip_add(struct pwm_chip *chip);
 435 int pwmchip_remove(struct pwm_chip *chip);
 436 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 437                                          unsigned int index,
 438                                          const char *label);
 439
 440 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
 441                 const struct of_phandle_args *args);
 442
 443 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
 444 struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id);
 445 void pwm_put(struct pwm_device *pwm);
 446
 447 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
 448 struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
 449                                    const char *con_id);
 450 void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
 451 #else
 452 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
 453 {
 454         return ERR_PTR(-ENODEV);
 455 }
 456
 457 static inline void pwm_free(struct pwm_device *pwm)
 458 {
 459 }
 460
 461 static inline int pwm_apply_state(struct pwm_device *pwm,
 462                                   const struct pwm_state *state)
 463 {
 464         return -ENOTSUPP;
 465 }
 466
 467 static inline int pwm_adjust_config(struct pwm_device *pwm)
 468 {
 469         return -ENOTSUPP;
 470 }
 471
 472 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 473                              int period_ns)
 474 {
 475         return -EINVAL;
 476 }
 477
 478 static inline int pwm_capture(struct pwm_device *pwm,
 479                               struct pwm_capture *result,
 480                               unsigned long timeout)
 481 {
 482         return -EINVAL;
 483 }
 484
 485 static inline int pwm_set_polarity(struct pwm_device *pwm,
 486                                    enum pwm_polarity polarity)
 487 {
 488         return -ENOTSUPP;
 489 }
 490
 491 static inline int pwm_enable(struct pwm_device *pwm)
 492 {
 493         return -EINVAL;
 494 }
 495
 496 static inline void pwm_disable(struct pwm_device *pwm)
 497 {
 498 }
 499
 500 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 501 {
 502         return -EINVAL;
 503 }
 504
 505 static inline void *pwm_get_chip_data(struct pwm_device *pwm)
 506 {
 507         return NULL;
 508 }
 509
 510 static inline int pwmchip_add(struct pwm_chip *chip)
 511 {
 512         return -EINVAL;
 513 }
 514
 515 static inline int pwmchip_add_inversed(struct pwm_chip *chip)
 516 {
 517         return -EINVAL;
 518 }
 519
 520 static inline int pwmchip_remove(struct pwm_chip *chip)
 521 {
 522         return -EINVAL;
 523 }
 524
 525 static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 526                                                        unsigned int index,
 527                                                        const char *label)
 528 {
 529         return ERR_PTR(-ENODEV);
 530 }
 531
 532 static inline struct pwm_device *pwm_get(struct device *dev,
 533                                          const char *consumer)
 534 {
 535         return ERR_PTR(-ENODEV);
 536 }
 537
 538 static inline struct pwm_device *of_pwm_get(struct device_node *np,
 539                                             const char *con_id)
 540 {
 541         return ERR_PTR(-ENODEV);
 542 }
 543
 544 static inline void pwm_put(struct pwm_device *pwm)
 545 {
 546 }
 547
 548 static inline struct pwm_device *devm_pwm_get(struct device *dev,
 549                                               const char *consumer)
 550 {
 551         return ERR_PTR(-ENODEV);
 552 }
 553
 554 static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
 555                                                  struct device_node *np,
 556                                                  const char *con_id)
 557 {
 558         return ERR_PTR(-ENODEV);
 559 }
 560
 561 static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
 562 {
 563 }
 564 #endif
 565
 566 static inline void pwm_apply_args(struct pwm_device *pwm)
 567 {
 568         struct pwm_state state = { };
 569
 570         /*
 571          * PWM users calling pwm_apply_args() expect to have a fresh config
 572          * where the polarity and period are set according to pwm_args info.
 573          * The problem is, polarity can only be changed when the PWM is
 574          * disabled.
 575          *
 576          * PWM drivers supporting hardware readout may declare the PWM device
 577          * as enabled, and prevent polarity setting, which changes from the
 578          * existing behavior, where all PWM devices are declared as disabled
 579          * at startup (even if they are actually enabled), thus authorizing
 580          * polarity setting.
 581          *
 582          * To fulfill this requirement, we apply a new state which disables
 583          * the PWM device and set the reference period and polarity config.
 584          *
 585          * Note that PWM users requiring a smooth handover between the
 586          * bootloader and the kernel (like critical regulators controlled by
 587          * PWM devices) will have to switch to the atomic API and avoid calling
 588          * pwm_apply_args().
 589          */
 590
 591         state.enabled = false;
 592         state.polarity = pwm->args.polarity;
 593         state.period = pwm->args.period;
 594
 595         pwm_apply_state(pwm, &state);
 596 }
 597
 598 struct pwm_lookup {
 599         struct list_head list;
 600         const char *provider;
 601         unsigned int index;
 602         const char *dev_id;
 603         const char *con_id;
 604         unsigned int period;
 605         enum pwm_polarity polarity;
 606         const char *module; /* optional, may be NULL */
 607 };
 608
 609 #define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id,     \
 610                                _period, _polarity, _module)             \
 611         {                                                               \
 612                 .provider = _provider,                                  \
 613                 .index = _index,                                        \
 614                 .dev_id = _dev_id,                                      \
 615                 .con_id = _con_id,                                      \
 616                 .period = _period,                                      \
 617                 .polarity = _polarity,                                  \
 618                 .module = _module,                                      \
 619         }
 620
 621 #define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
 622         PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
 623                                _polarity, NULL)
 624
 625 #if IS_ENABLED(CONFIG_PWM)
 626 void pwm_add_table(struct pwm_lookup *table, size_t num);
 627 void pwm_remove_table(struct pwm_lookup *table, size_t num);
 628 #else
 629 static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
 630 {
 631 }
 632
 633 static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
 634 {
 635 }
 636 #endif
 637
 638 #ifdef CONFIG_PWM_SYSFS
 639 void pwmchip_sysfs_export(struct pwm_chip *chip);
 640 void pwmchip_sysfs_unexport(struct pwm_chip *chip);
 641 void pwmchip_sysfs_unexport_children(struct pwm_chip *chip);
 642 #else
 643 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
 644 {
 645 }
 646
 647 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
 648 {
 649 }
 650
 651 static inline void pwmchip_sysfs_unexport_children(struct pwm_chip *chip)
 652 {
 653 }
 654 #endif /* CONFIG_PWM_SYSFS */
 655
 656 #endif /* __LINUX_PWM_H */