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  * @can_sleep: must be true if the .config(), .enable() or .disable()
 291  *             operations may sleep
 292  */
 293 struct pwm_chip {
 294         struct device *dev;
 295         struct list_head list;
 296         const struct pwm_ops *ops;
 297         int base;
 298         unsigned int npwm;
 299
 300         struct pwm_device *pwms;
 301
 302         struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
 303                                         const struct of_phandle_args *args);
 304         unsigned int of_pwm_n_cells;
 305         bool can_sleep;
 306 };
 307
 308 /**
 309  * struct pwm_capture - PWM capture data
 310  * @period: period of the PWM signal (in nanoseconds)
 311  * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
 312  */
 313 struct pwm_capture {
 314         unsigned int period;
 315         unsigned int duty_cycle;
 316 };
 317
 318 #if IS_ENABLED(CONFIG_PWM)
 319 /* PWM user APIs */
 320 struct pwm_device *pwm_request(int pwm_id, const char *label);
 321 void pwm_free(struct pwm_device *pwm);
 322 int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
 323 int pwm_adjust_config(struct pwm_device *pwm);
 324
 325 /**
 326  * pwm_config() - change a PWM device configuration
 327  * @pwm: PWM device
 328  * @duty_ns: "on" time (in nanoseconds)
 329  * @period_ns: duration (in nanoseconds) of one cycle
 330  *
 331  * Returns: 0 on success or a negative error code on failure.
 332  */
 333 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 334                              int period_ns)
 335 {
 336         struct pwm_state state;
 337
 338         if (!pwm)
 339                 return -EINVAL;
 340
 341         if (duty_ns < 0 || period_ns < 0)
 342                 return -EINVAL;
 343
 344         pwm_get_state(pwm, &state);
 345         if (state.duty_cycle == duty_ns && state.period == period_ns)
 346                 return 0;
 347
 348         state.duty_cycle = duty_ns;
 349         state.period = period_ns;
 350         return pwm_apply_state(pwm, &state);
 351 }
 352
 353 /**
 354  * pwm_set_polarity() - configure the polarity of a PWM signal
 355  * @pwm: PWM device
 356  * @polarity: new polarity of the PWM signal
 357  *
 358  * Note that the polarity cannot be configured while the PWM device is
 359  * enabled.
 360  *
 361  * Returns: 0 on success or a negative error code on failure.
 362  */
 363 static inline int pwm_set_polarity(struct pwm_device *pwm,
 364                                    enum pwm_polarity polarity)
 365 {
 366         struct pwm_state state;
 367
 368         if (!pwm)
 369                 return -EINVAL;
 370
 371         pwm_get_state(pwm, &state);
 372         if (state.polarity == polarity)
 373                 return 0;
 374
 375         /*
 376          * Changing the polarity of a running PWM without adjusting the
 377          * dutycycle/period value is a bit risky (can introduce glitches).
 378          * Return -EBUSY in this case.
 379          * Note that this is allowed when using pwm_apply_state() because
 380          * the user specifies all the parameters.
 381          */
 382         if (state.enabled)
 383                 return -EBUSY;
 384
 385         state.polarity = polarity;
 386         return pwm_apply_state(pwm, &state);
 387 }
 388
 389 /**
 390  * pwm_enable() - start a PWM output toggling
 391  * @pwm: PWM device
 392  *
 393  * Returns: 0 on success or a negative error code on failure.
 394  */
 395 static inline int pwm_enable(struct pwm_device *pwm)
 396 {
 397         struct pwm_state state;
 398
 399         if (!pwm)
 400                 return -EINVAL;
 401
 402         pwm_get_state(pwm, &state);
 403         if (state.enabled)
 404                 return 0;
 405
 406         state.enabled = true;
 407         return pwm_apply_state(pwm, &state);
 408 }
 409
 410 /**
 411  * pwm_disable() - stop a PWM output toggling
 412  * @pwm: PWM device
 413  */
 414 static inline void pwm_disable(struct pwm_device *pwm)
 415 {
 416         struct pwm_state state;
 417
 418         if (!pwm)
 419                 return;
 420
 421         pwm_get_state(pwm, &state);
 422         if (!state.enabled)
 423                 return;
 424
 425         state.enabled = false;
 426         pwm_apply_state(pwm, &state);
 427 }
 428
 429 /* PWM provider APIs */
 430 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
 431                 unsigned long timeout);
 432 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 433 void *pwm_get_chip_data(struct pwm_device *pwm);
 434
 435 int pwmchip_add_with_polarity(struct pwm_chip *chip,
 436                               enum pwm_polarity polarity);
 437 int pwmchip_add(struct pwm_chip *chip);
 438 int pwmchip_remove(struct pwm_chip *chip);
 439 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 440                                          unsigned int index,
 441                                          const char *label);
 442
 443 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
 444                 const struct of_phandle_args *args);
 445
 446 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
 447 struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id);
 448 void pwm_put(struct pwm_device *pwm);
 449
 450 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
 451 struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
 452                                    const char *con_id);
 453 void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
 454
 455 bool pwm_can_sleep(struct pwm_device *pwm);
 456 #else
 457 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
 458 {
 459         return ERR_PTR(-ENODEV);
 460 }
 461
 462 static inline void pwm_free(struct pwm_device *pwm)
 463 {
 464 }
 465
 466 static inline int pwm_apply_state(struct pwm_device *pwm,
 467                                   const struct pwm_state *state)
 468 {
 469         return -ENOTSUPP;
 470 }
 471
 472 static inline int pwm_adjust_config(struct pwm_device *pwm)
 473 {
 474         return -ENOTSUPP;
 475 }
 476
 477 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 478                              int period_ns)
 479 {
 480         return -EINVAL;
 481 }
 482
 483 static inline int pwm_capture(struct pwm_device *pwm,
 484                               struct pwm_capture *result,
 485                               unsigned long timeout)
 486 {
 487         return -EINVAL;
 488 }
 489
 490 static inline int pwm_set_polarity(struct pwm_device *pwm,
 491                                    enum pwm_polarity polarity)
 492 {
 493         return -ENOTSUPP;
 494 }
 495
 496 static inline int pwm_enable(struct pwm_device *pwm)
 497 {
 498         return -EINVAL;
 499 }
 500
 501 static inline void pwm_disable(struct pwm_device *pwm)
 502 {
 503 }
 504
 505 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 506 {
 507         return -EINVAL;
 508 }
 509
 510 static inline void *pwm_get_chip_data(struct pwm_device *pwm)
 511 {
 512         return NULL;
 513 }
 514
 515 static inline int pwmchip_add(struct pwm_chip *chip)
 516 {
 517         return -EINVAL;
 518 }
 519
 520 static inline int pwmchip_add_inversed(struct pwm_chip *chip)
 521 {
 522         return -EINVAL;
 523 }
 524
 525 static inline int pwmchip_remove(struct pwm_chip *chip)
 526 {
 527         return -EINVAL;
 528 }
 529
 530 static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 531                                                        unsigned int index,
 532                                                        const char *label)
 533 {
 534         return ERR_PTR(-ENODEV);
 535 }
 536
 537 static inline struct pwm_device *pwm_get(struct device *dev,
 538                                          const char *consumer)
 539 {
 540         return ERR_PTR(-ENODEV);
 541 }
 542
 543 static inline struct pwm_device *of_pwm_get(struct device_node *np,
 544                                             const char *con_id)
 545 {
 546         return ERR_PTR(-ENODEV);
 547 }
 548
 549 static inline void pwm_put(struct pwm_device *pwm)
 550 {
 551 }
 552
 553 static inline struct pwm_device *devm_pwm_get(struct device *dev,
 554                                               const char *consumer)
 555 {
 556         return ERR_PTR(-ENODEV);
 557 }
 558
 559 static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
 560                                                  struct device_node *np,
 561                                                  const char *con_id)
 562 {
 563         return ERR_PTR(-ENODEV);
 564 }
 565
 566 static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
 567 {
 568 }
 569
 570 static inline bool pwm_can_sleep(struct pwm_device *pwm)
 571 {
 572         return false;
 573 }
 574 #endif
 575
 576 static inline void pwm_apply_args(struct pwm_device *pwm)
 577 {
 578         struct pwm_state state = { };
 579
 580         /*
 581          * PWM users calling pwm_apply_args() expect to have a fresh config
 582          * where the polarity and period are set according to pwm_args info.
 583          * The problem is, polarity can only be changed when the PWM is
 584          * disabled.
 585          *
 586          * PWM drivers supporting hardware readout may declare the PWM device
 587          * as enabled, and prevent polarity setting, which changes from the
 588          * existing behavior, where all PWM devices are declared as disabled
 589          * at startup (even if they are actually enabled), thus authorizing
 590          * polarity setting.
 591          *
 592          * To fulfill this requirement, we apply a new state which disables
 593          * the PWM device and set the reference period and polarity config.
 594          *
 595          * Note that PWM users requiring a smooth handover between the
 596          * bootloader and the kernel (like critical regulators controlled by
 597          * PWM devices) will have to switch to the atomic API and avoid calling
 598          * pwm_apply_args().
 599          */
 600
 601         state.enabled = false;
 602         state.polarity = pwm->args.polarity;
 603         state.period = pwm->args.period;
 604
 605         pwm_apply_state(pwm, &state);
 606 }
 607
 608 struct pwm_lookup {
 609         struct list_head list;
 610         const char *provider;
 611         unsigned int index;
 612         const char *dev_id;
 613         const char *con_id;
 614         unsigned int period;
 615         enum pwm_polarity polarity;
 616 };
 617
 618 #define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
 619         {                                               \
 620                 .provider = _provider,                  \
 621                 .index = _index,                        \
 622                 .dev_id = _dev_id,                      \
 623                 .con_id = _con_id,                      \
 624                 .period = _period,                      \
 625                 .polarity = _polarity                   \
 626         }
 627
 628 #if IS_ENABLED(CONFIG_PWM)
 629 void pwm_add_table(struct pwm_lookup *table, size_t num);
 630 void pwm_remove_table(struct pwm_lookup *table, size_t num);
 631 #else
 632 static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
 633 {
 634 }
 635
 636 static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
 637 {
 638 }
 639 #endif
 640
 641 #ifdef CONFIG_PWM_SYSFS
 642 void pwmchip_sysfs_export(struct pwm_chip *chip);
 643 void pwmchip_sysfs_unexport(struct pwm_chip *chip);
 644 #else
 645 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
 646 {
 647 }
 648
 649 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
 650 {
 651 }
 652 #endif /* CONFIG_PWM_SYSFS */
 653
 654 #endif /* __LINUX_PWM_H */