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 */ 658