drivers/hwmon/pwm-fan.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
   4  *
   5  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   6  *
   7  * Author: Kamil Debski <k.debski@samsung.com>
   8  */
   9
  10 #include <linux/hwmon.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/module.h>
  13 #include <linux/mutex.h>
  14 #include <linux/of.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/pwm.h>
  17 #include <linux/regulator/consumer.h>
  18 #include <linux/sysfs.h>
  19 #include <linux/thermal.h>
  20 #include <linux/timer.h>
  21
  22 #define MAX_PWM 255
  23
  24 struct pwm_fan_tach {
  25         int irq;
  26         atomic_t pulses;
  27         unsigned int rpm;
  28         u8 pulses_per_revolution;
  29 };
  30
  31 enum pwm_fan_enable_mode {
  32         pwm_off_reg_off,
  33         pwm_disable_reg_enable,
  34         pwm_enable_reg_enable,
  35         pwm_disable_reg_disable,
  36 };
  37
  38 struct pwm_fan_ctx {
  39         struct device *dev;
  40
  41         struct mutex lock;
  42         struct pwm_device *pwm;
  43         struct pwm_state pwm_state;
  44         struct regulator *reg_en;
  45         enum pwm_fan_enable_mode enable_mode;
  46         bool regulator_enabled;
  47         bool enabled;
  48
  49         int tach_count;
  50         struct pwm_fan_tach *tachs;
  51         ktime_t sample_start;
  52         struct timer_list rpm_timer;
  53
  54         unsigned int pwm_value;
  55         unsigned int pwm_fan_state;
  56         unsigned int pwm_fan_max_state;
  57         unsigned int *pwm_fan_cooling_levels;
  58         struct thermal_cooling_device *cdev;
  59
  60         struct hwmon_chip_info info;
  61         struct hwmon_channel_info fan_channel;
  62 };
  63
  64 /* This handler assumes self resetting edge triggered interrupt. */
  65 static irqreturn_t pulse_handler(int irq, void *dev_id)
  66 {
  67         struct pwm_fan_tach *tach = dev_id;
  68
  69         atomic_inc(&tach->pulses);
  70
  71         return IRQ_HANDLED;
  72 }
  73
  74 static void sample_timer(struct timer_list *t)
  75 {
  76         struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
  77         unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
  78         int i;
  79
  80         if (delta) {
  81                 for (i = 0; i < ctx->tach_count; i++) {
  82                         struct pwm_fan_tach *tach = &ctx->tachs[i];
  83                         int pulses;
  84
  85                         pulses = atomic_read(&tach->pulses);
  86                         atomic_sub(pulses, &tach->pulses);
  87                         tach->rpm = (unsigned int)(pulses * 1000 * 60) /
  88                                 (tach->pulses_per_revolution * delta);
  89                 }
  90
  91                 ctx->sample_start = ktime_get();
  92         }
  93
  94         mod_timer(&ctx->rpm_timer, jiffies + HZ);
  95 }
  96
  97 static void pwm_fan_enable_mode_2_state(int enable_mode,
  98                                         struct pwm_state *state,
  99                                         bool *enable_regulator)
 100 {
 101         switch (enable_mode) {
 102         case pwm_disable_reg_enable:
 103                 /* disable pwm, keep regulator enabled */
 104                 state->enabled = false;
 105                 *enable_regulator = true;
 106                 break;
 107         case pwm_enable_reg_enable:
 108                 /* keep pwm and regulator enabled */
 109                 state->enabled = true;
 110                 *enable_regulator = true;
 111                 break;
 112         case pwm_off_reg_off:
 113         case pwm_disable_reg_disable:
 114                 /* disable pwm and regulator */
 115                 state->enabled = false;
 116                 *enable_regulator = false;
 117         }
 118 }
 119
 120 static int pwm_fan_switch_power(struct pwm_fan_ctx *ctx, bool on)
 121 {
 122         int ret = 0;
 123
 124         if (!ctx->reg_en)
 125                 return ret;
 126
 127         if (!ctx->regulator_enabled && on) {
 128                 ret = regulator_enable(ctx->reg_en);
 129                 if (ret == 0)
 130                         ctx->regulator_enabled = true;
 131         } else if (ctx->regulator_enabled && !on) {
 132                 ret = regulator_disable(ctx->reg_en);
 133                 if (ret == 0)
 134                         ctx->regulator_enabled = false;
 135         }
 136         return ret;
 137 }
 138
 139 static int pwm_fan_power_on(struct pwm_fan_ctx *ctx)
 140 {
 141         struct pwm_state *state = &ctx->pwm_state;
 142         int ret;
 143
 144         if (ctx->enabled)
 145                 return 0;
 146
 147         ret = pwm_fan_switch_power(ctx, true);
 148         if (ret < 0) {
 149                 dev_err(ctx->dev, "failed to enable power supply\n");
 150                 return ret;
 151         }
 152
 153         state->enabled = true;
 154         ret = pwm_apply_state(ctx->pwm, state);
 155         if (ret) {
 156                 dev_err(ctx->dev, "failed to enable PWM\n");
 157                 goto disable_regulator;
 158         }
 159
 160         ctx->enabled = true;
 161
 162         return 0;
 163
 164 disable_regulator:
 165         pwm_fan_switch_power(ctx, false);
 166         return ret;
 167 }
 168
 169 static int pwm_fan_power_off(struct pwm_fan_ctx *ctx)
 170 {
 171         struct pwm_state *state = &ctx->pwm_state;
 172         bool enable_regulator = false;
 173         int ret;
 174
 175         if (!ctx->enabled)
 176                 return 0;
 177
 178         pwm_fan_enable_mode_2_state(ctx->enable_mode,
 179                                     state,
 180                                     &enable_regulator);
 181
 182         state->enabled = false;
 183         state->duty_cycle = 0;
 184         ret = pwm_apply_state(ctx->pwm, state);
 185         if (ret) {
 186                 dev_err(ctx->dev, "failed to disable PWM\n");
 187                 return ret;
 188         }
 189
 190         pwm_fan_switch_power(ctx, enable_regulator);
 191
 192         ctx->enabled = false;
 193
 194         return 0;
 195 }
 196
 197 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
 198 {
 199         struct pwm_state *state = &ctx->pwm_state;
 200         unsigned long period;
 201         int ret = 0;
 202
 203         if (pwm > 0) {
 204                 if (ctx->enable_mode == pwm_off_reg_off)
 205                         /* pwm-fan hard disabled */
 206                         return 0;
 207
 208                 period = state->period;
 209                 state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
 210                 ret = pwm_apply_state(ctx->pwm, state);
 211                 if (ret)
 212                         return ret;
 213                 ret = pwm_fan_power_on(ctx);
 214         } else {
 215                 ret = pwm_fan_power_off(ctx);
 216         }
 217         if (!ret)
 218                 ctx->pwm_value = pwm;
 219
 220         return ret;
 221 }
 222
 223 static int set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
 224 {
 225         int ret;
 226
 227         mutex_lock(&ctx->lock);
 228         ret = __set_pwm(ctx, pwm);
 229         mutex_unlock(&ctx->lock);
 230
 231         return ret;
 232 }
 233
 234 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
 235 {
 236         int i;
 237
 238         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
 239                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
 240                         break;
 241
 242         ctx->pwm_fan_state = i;
 243 }
 244
 245 static int pwm_fan_update_enable(struct pwm_fan_ctx *ctx, long val)
 246 {
 247         int ret = 0;
 248         int old_val;
 249
 250         mutex_lock(&ctx->lock);
 251
 252         if (ctx->enable_mode == val)
 253                 goto out;
 254
 255         old_val = ctx->enable_mode;
 256         ctx->enable_mode = val;
 257
 258         if (val == 0) {
 259                 /* Disable pwm-fan unconditionally */
 260                 if (ctx->enabled)
 261                         ret = __set_pwm(ctx, 0);
 262                 else
 263                         ret = pwm_fan_switch_power(ctx, false);
 264                 if (ret)
 265                         ctx->enable_mode = old_val;
 266                 pwm_fan_update_state(ctx, 0);
 267         } else {
 268                 /*
 269                  * Change PWM and/or regulator state if currently disabled
 270                  * Nothing to do if currently enabled
 271                  */
 272                 if (!ctx->enabled) {
 273                         struct pwm_state *state = &ctx->pwm_state;
 274                         bool enable_regulator = false;
 275
 276                         state->duty_cycle = 0;
 277                         pwm_fan_enable_mode_2_state(val,
 278                                                     state,
 279                                                     &enable_regulator);
 280
 281                         pwm_apply_state(ctx->pwm, state);
 282                         pwm_fan_switch_power(ctx, enable_regulator);
 283                         pwm_fan_update_state(ctx, 0);
 284                 }
 285         }
 286 out:
 287         mutex_unlock(&ctx->lock);
 288
 289         return ret;
 290 }
 291
 292 static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
 293                          u32 attr, int channel, long val)
 294 {
 295         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 296         int ret;
 297
 298         switch (attr) {
 299         case hwmon_pwm_input:
 300                 if (val < 0 || val > MAX_PWM)
 301                         return -EINVAL;
 302                 ret = set_pwm(ctx, val);
 303                 if (ret)
 304                         return ret;
 305                 pwm_fan_update_state(ctx, val);
 306                 break;
 307         case hwmon_pwm_enable:
 308                 if (val < 0 || val > 3)
 309                         ret = -EINVAL;
 310                 else
 311                         ret = pwm_fan_update_enable(ctx, val);
 312
 313                 return ret;
 314         default:
 315                 return -EOPNOTSUPP;
 316         }
 317
 318         return 0;
 319 }
 320
 321 static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
 322                         u32 attr, int channel, long *val)
 323 {
 324         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 325
 326         switch (type) {
 327         case hwmon_pwm:
 328                 switch (attr) {
 329                 case hwmon_pwm_input:
 330                         *val = ctx->pwm_value;
 331                         return 0;
 332                 case hwmon_pwm_enable:
 333                         *val = ctx->enable_mode;
 334                         return 0;
 335                 }
 336                 return -EOPNOTSUPP;
 337         case hwmon_fan:
 338                 *val = ctx->tachs[channel].rpm;
 339                 return 0;
 340
 341         default:
 342                 return -ENOTSUPP;
 343         }
 344 }
 345
 346 static umode_t pwm_fan_is_visible(const void *data,
 347                                   enum hwmon_sensor_types type,
 348                                   u32 attr, int channel)
 349 {
 350         switch (type) {
 351         case hwmon_pwm:
 352                 return 0644;
 353
 354         case hwmon_fan:
 355                 return 0444;
 356
 357         default:
 358                 return 0;
 359         }
 360 }
 361
 362 static const struct hwmon_ops pwm_fan_hwmon_ops = {
 363         .is_visible = pwm_fan_is_visible,
 364         .read = pwm_fan_read,
 365         .write = pwm_fan_write,
 366 };
 367
 368 /* thermal cooling device callbacks */
 369 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 370                                  unsigned long *state)
 371 {
 372         struct pwm_fan_ctx *ctx = cdev->devdata;
 373
 374         if (!ctx)
 375                 return -EINVAL;
 376
 377         *state = ctx->pwm_fan_max_state;
 378
 379         return 0;
 380 }
 381
 382 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 383                                  unsigned long *state)
 384 {
 385         struct pwm_fan_ctx *ctx = cdev->devdata;
 386
 387         if (!ctx)
 388                 return -EINVAL;
 389
 390         *state = ctx->pwm_fan_state;
 391
 392         return 0;
 393 }
 394
 395 static int
 396 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 397 {
 398         struct pwm_fan_ctx *ctx = cdev->devdata;
 399         int ret;
 400
 401         if (!ctx || (state > ctx->pwm_fan_max_state))
 402                 return -EINVAL;
 403
 404         if (state == ctx->pwm_fan_state)
 405                 return 0;
 406
 407         ret = set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 408         if (ret) {
 409                 dev_err(&cdev->device, "Cannot set pwm!\n");
 410                 return ret;
 411         }
 412
 413         ctx->pwm_fan_state = state;
 414
 415         return ret;
 416 }
 417
 418 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 419         .get_max_state = pwm_fan_get_max_state,
 420         .get_cur_state = pwm_fan_get_cur_state,
 421         .set_cur_state = pwm_fan_set_cur_state,
 422 };
 423
 424 static int pwm_fan_of_get_cooling_data(struct device *dev,
 425                                        struct pwm_fan_ctx *ctx)
 426 {
 427         struct device_node *np = dev->of_node;
 428         int num, i, ret;
 429
 430         if (!of_property_present(np, "cooling-levels"))
 431                 return 0;
 432
 433         ret = of_property_count_u32_elems(np, "cooling-levels");
 434         if (ret <= 0) {
 435                 dev_err(dev, "Wrong data!\n");
 436                 return ret ? : -EINVAL;
 437         }
 438
 439         num = ret;
 440         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 441                                                    GFP_KERNEL);
 442         if (!ctx->pwm_fan_cooling_levels)
 443                 return -ENOMEM;
 444
 445         ret = of_property_read_u32_array(np, "cooling-levels",
 446                                          ctx->pwm_fan_cooling_levels, num);
 447         if (ret) {
 448                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 449                 return ret;
 450         }
 451
 452         for (i = 0; i < num; i++) {
 453                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 454                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 455                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 456                         return -EINVAL;
 457                 }
 458         }
 459
 460         ctx->pwm_fan_max_state = num - 1;
 461
 462         return 0;
 463 }
 464
 465 static void pwm_fan_cleanup(void *__ctx)
 466 {
 467         struct pwm_fan_ctx *ctx = __ctx;
 468
 469         del_timer_sync(&ctx->rpm_timer);
 470         /* Switch off everything */
 471         ctx->enable_mode = pwm_disable_reg_disable;
 472         pwm_fan_power_off(ctx);
 473 }
 474
 475 static int pwm_fan_probe(struct platform_device *pdev)
 476 {
 477         struct thermal_cooling_device *cdev;
 478         struct device *dev = &pdev->dev;
 479         struct pwm_fan_ctx *ctx;
 480         struct device *hwmon;
 481         int ret;
 482         const struct hwmon_channel_info **channels;
 483         u32 *fan_channel_config;
 484         int channel_count = 1;  /* We always have a PWM channel. */
 485         int i;
 486
 487         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 488         if (!ctx)
 489                 return -ENOMEM;
 490
 491         mutex_init(&ctx->lock);
 492
 493         ctx->dev = &pdev->dev;
 494         ctx->pwm = devm_pwm_get(dev, NULL);
 495         if (IS_ERR(ctx->pwm))
 496                 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
 497
 498         platform_set_drvdata(pdev, ctx);
 499
 500         ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 501         if (IS_ERR(ctx->reg_en)) {
 502                 if (PTR_ERR(ctx->reg_en) != -ENODEV)
 503                         return PTR_ERR(ctx->reg_en);
 504
 505                 ctx->reg_en = NULL;
 506         }
 507
 508         pwm_init_state(ctx->pwm, &ctx->pwm_state);
 509
 510         /*
 511          * PWM fans are controlled solely by the duty cycle of the PWM signal,
 512          * they do not care about the exact timing. Thus set usage_power to true
 513          * to allow less flexible hardware to work as a PWM source for fan
 514          * control.
 515          */
 516         ctx->pwm_state.usage_power = true;
 517
 518         /*
 519          * set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
 520          * long. Check this here to prevent the fan running at a too low
 521          * frequency.
 522          */
 523         if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
 524                 dev_err(dev, "Configured period too big\n");
 525                 return -EINVAL;
 526         }
 527
 528         ctx->enable_mode = pwm_disable_reg_enable;
 529
 530         /*
 531          * Set duty cycle to maximum allowed and enable PWM output as well as
 532          * the regulator. In case of error nothing is changed
 533          */
 534         ret = set_pwm(ctx, MAX_PWM);
 535         if (ret) {
 536                 dev_err(dev, "Failed to configure PWM: %d\n", ret);
 537                 return ret;
 538         }
 539         timer_setup(&ctx->rpm_timer, sample_timer, 0);
 540         ret = devm_add_action_or_reset(dev, pwm_fan_cleanup, ctx);
 541         if (ret)
 542                 return ret;
 543
 544         ctx->tach_count = platform_irq_count(pdev);
 545         if (ctx->tach_count < 0)
 546                 return dev_err_probe(dev, ctx->tach_count,
 547                                      "Could not get number of fan tachometer inputs\n");
 548         dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
 549
 550         if (ctx->tach_count) {
 551                 channel_count++;        /* We also have a FAN channel. */
 552
 553                 ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
 554                                           sizeof(struct pwm_fan_tach),
 555                                           GFP_KERNEL);
 556                 if (!ctx->tachs)
 557                         return -ENOMEM;
 558
 559                 ctx->fan_channel.type = hwmon_fan;
 560                 fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
 561                                                   sizeof(u32), GFP_KERNEL);
 562                 if (!fan_channel_config)
 563                         return -ENOMEM;
 564                 ctx->fan_channel.config = fan_channel_config;
 565         }
 566
 567         channels = devm_kcalloc(dev, channel_count + 1,
 568                                 sizeof(struct hwmon_channel_info *), GFP_KERNEL);
 569         if (!channels)
 570                 return -ENOMEM;
 571
 572         channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE);
 573
 574         for (i = 0; i < ctx->tach_count; i++) {
 575                 struct pwm_fan_tach *tach = &ctx->tachs[i];
 576                 u32 ppr = 2;
 577
 578                 tach->irq = platform_get_irq(pdev, i);
 579                 if (tach->irq == -EPROBE_DEFER)
 580                         return tach->irq;
 581                 if (tach->irq > 0) {
 582                         ret = devm_request_irq(dev, tach->irq, pulse_handler, 0,
 583                                                pdev->name, tach);
 584                         if (ret) {
 585                                 dev_err(dev,
 586                                         "Failed to request interrupt: %d\n",
 587                                         ret);
 588                                 return ret;
 589                         }
 590                 }
 591
 592                 of_property_read_u32_index(dev->of_node,
 593                                            "pulses-per-revolution",
 594                                            i,
 595                                            &ppr);
 596                 tach->pulses_per_revolution = ppr;
 597                 if (!tach->pulses_per_revolution) {
 598                         dev_err(dev, "pulses-per-revolution can't be zero.\n");
 599                         return -EINVAL;
 600                 }
 601
 602                 fan_channel_config[i] = HWMON_F_INPUT;
 603
 604                 dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
 605                         i, tach->irq, tach->pulses_per_revolution);
 606         }
 607
 608         if (ctx->tach_count > 0) {
 609                 ctx->sample_start = ktime_get();
 610                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 611
 612                 channels[1] = &ctx->fan_channel;
 613         }
 614
 615         ctx->info.ops = &pwm_fan_hwmon_ops;
 616         ctx->info.info = channels;
 617
 618         hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
 619                                                      ctx, &ctx->info, NULL);
 620         if (IS_ERR(hwmon)) {
 621                 dev_err(dev, "Failed to register hwmon device\n");
 622                 return PTR_ERR(hwmon);
 623         }
 624
 625         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 626         if (ret)
 627                 return ret;
 628
 629         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 630         if (IS_ENABLED(CONFIG_THERMAL)) {
 631                 cdev = devm_thermal_of_cooling_device_register(dev,
 632                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 633                 if (IS_ERR(cdev)) {
 634                         ret = PTR_ERR(cdev);
 635                         dev_err(dev,
 636                                 "Failed to register pwm-fan as cooling device: %d\n",
 637                                 ret);
 638                         return ret;
 639                 }
 640                 ctx->cdev = cdev;
 641         }
 642
 643         return 0;
 644 }
 645
 646 static void pwm_fan_shutdown(struct platform_device *pdev)
 647 {
 648         struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
 649
 650         pwm_fan_cleanup(ctx);
 651 }
 652
 653 static int pwm_fan_suspend(struct device *dev)
 654 {
 655         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 656
 657         return pwm_fan_power_off(ctx);
 658 }
 659
 660 static int pwm_fan_resume(struct device *dev)
 661 {
 662         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 663
 664         return set_pwm(ctx, ctx->pwm_value);
 665 }
 666
 667 static DEFINE_SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 668
 669 static const struct of_device_id of_pwm_fan_match[] = {
 670         { .compatible = "pwm-fan", },
 671         {},
 672 };
 673 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 674
 675 static struct platform_driver pwm_fan_driver = {
 676         .probe          = pwm_fan_probe,
 677         .shutdown       = pwm_fan_shutdown,
 678         .driver = {
 679                 .name           = "pwm-fan",
 680                 .pm             = pm_sleep_ptr(&pwm_fan_pm),
 681                 .of_match_table = of_pwm_fan_match,
 682         },
 683 };
 684
 685 module_platform_driver(pwm_fan_driver);
 686
 687 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 688 MODULE_ALIAS("platform:pwm-fan");
 689 MODULE_DESCRIPTION("PWM FAN driver");
 690 MODULE_LICENSE("GPL");