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                 ret = __set_pwm(ctx, 0);
 261                 if (ret)
 262                         ctx->enable_mode = old_val;
 263                 pwm_fan_update_state(ctx, 0);
 264         } else {
 265                 /*
 266                  * Change PWM and/or regulator state if currently disabled
 267                  * Nothing to do if currently enabled
 268                  */
 269                 if (!ctx->enabled) {
 270                         struct pwm_state *state = &ctx->pwm_state;
 271                         bool enable_regulator = false;
 272
 273                         state->duty_cycle = 0;
 274                         pwm_fan_enable_mode_2_state(val,
 275                                                     state,
 276                                                     &enable_regulator);
 277
 278                         pwm_apply_state(ctx->pwm, state);
 279                         pwm_fan_switch_power(ctx, enable_regulator);
 280                         pwm_fan_update_state(ctx, 0);
 281                 }
 282         }
 283 out:
 284         mutex_unlock(&ctx->lock);
 285
 286         return ret;
 287 }
 288
 289 static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
 290                          u32 attr, int channel, long val)
 291 {
 292         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 293         int ret;
 294
 295         switch (attr) {
 296         case hwmon_pwm_input:
 297                 if (val < 0 || val > MAX_PWM)
 298                         return -EINVAL;
 299                 ret = set_pwm(ctx, val);
 300                 if (ret)
 301                         return ret;
 302                 pwm_fan_update_state(ctx, val);
 303                 break;
 304         case hwmon_pwm_enable:
 305                 if (val < 0 || val > 3)
 306                         ret = -EINVAL;
 307                 else
 308                         ret = pwm_fan_update_enable(ctx, val);
 309
 310                 return ret;
 311         default:
 312                 return -EOPNOTSUPP;
 313         }
 314
 315         return 0;
 316 }
 317
 318 static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
 319                         u32 attr, int channel, long *val)
 320 {
 321         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 322
 323         switch (type) {
 324         case hwmon_pwm:
 325                 switch (attr) {
 326                 case hwmon_pwm_input:
 327                         *val = ctx->pwm_value;
 328                         return 0;
 329                 case hwmon_pwm_enable:
 330                         *val = ctx->enable_mode;
 331                         return 0;
 332                 }
 333                 return -EOPNOTSUPP;
 334         case hwmon_fan:
 335                 *val = ctx->tachs[channel].rpm;
 336                 return 0;
 337
 338         default:
 339                 return -ENOTSUPP;
 340         }
 341 }
 342
 343 static umode_t pwm_fan_is_visible(const void *data,
 344                                   enum hwmon_sensor_types type,
 345                                   u32 attr, int channel)
 346 {
 347         switch (type) {
 348         case hwmon_pwm:
 349                 return 0644;
 350
 351         case hwmon_fan:
 352                 return 0444;
 353
 354         default:
 355                 return 0;
 356         }
 357 }
 358
 359 static const struct hwmon_ops pwm_fan_hwmon_ops = {
 360         .is_visible = pwm_fan_is_visible,
 361         .read = pwm_fan_read,
 362         .write = pwm_fan_write,
 363 };
 364
 365 /* thermal cooling device callbacks */
 366 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 367                                  unsigned long *state)
 368 {
 369         struct pwm_fan_ctx *ctx = cdev->devdata;
 370
 371         if (!ctx)
 372                 return -EINVAL;
 373
 374         *state = ctx->pwm_fan_max_state;
 375
 376         return 0;
 377 }
 378
 379 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 380                                  unsigned long *state)
 381 {
 382         struct pwm_fan_ctx *ctx = cdev->devdata;
 383
 384         if (!ctx)
 385                 return -EINVAL;
 386
 387         *state = ctx->pwm_fan_state;
 388
 389         return 0;
 390 }
 391
 392 static int
 393 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 394 {
 395         struct pwm_fan_ctx *ctx = cdev->devdata;
 396         int ret;
 397
 398         if (!ctx || (state > ctx->pwm_fan_max_state))
 399                 return -EINVAL;
 400
 401         if (state == ctx->pwm_fan_state)
 402                 return 0;
 403
 404         ret = set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 405         if (ret) {
 406                 dev_err(&cdev->device, "Cannot set pwm!\n");
 407                 return ret;
 408         }
 409
 410         ctx->pwm_fan_state = state;
 411
 412         return ret;
 413 }
 414
 415 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 416         .get_max_state = pwm_fan_get_max_state,
 417         .get_cur_state = pwm_fan_get_cur_state,
 418         .set_cur_state = pwm_fan_set_cur_state,
 419 };
 420
 421 static int pwm_fan_of_get_cooling_data(struct device *dev,
 422                                        struct pwm_fan_ctx *ctx)
 423 {
 424         struct device_node *np = dev->of_node;
 425         int num, i, ret;
 426
 427         if (!of_find_property(np, "cooling-levels", NULL))
 428                 return 0;
 429
 430         ret = of_property_count_u32_elems(np, "cooling-levels");
 431         if (ret <= 0) {
 432                 dev_err(dev, "Wrong data!\n");
 433                 return ret ? : -EINVAL;
 434         }
 435
 436         num = ret;
 437         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 438                                                    GFP_KERNEL);
 439         if (!ctx->pwm_fan_cooling_levels)
 440                 return -ENOMEM;
 441
 442         ret = of_property_read_u32_array(np, "cooling-levels",
 443                                          ctx->pwm_fan_cooling_levels, num);
 444         if (ret) {
 445                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 446                 return ret;
 447         }
 448
 449         for (i = 0; i < num; i++) {
 450                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 451                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 452                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 453                         return -EINVAL;
 454                 }
 455         }
 456
 457         ctx->pwm_fan_max_state = num - 1;
 458
 459         return 0;
 460 }
 461
 462 static void pwm_fan_cleanup(void *__ctx)
 463 {
 464         struct pwm_fan_ctx *ctx = __ctx;
 465
 466         del_timer_sync(&ctx->rpm_timer);
 467         /* Switch off everything */
 468         ctx->enable_mode = pwm_disable_reg_disable;
 469         pwm_fan_power_off(ctx);
 470 }
 471
 472 static int pwm_fan_probe(struct platform_device *pdev)
 473 {
 474         struct thermal_cooling_device *cdev;
 475         struct device *dev = &pdev->dev;
 476         struct pwm_fan_ctx *ctx;
 477         struct device *hwmon;
 478         int ret;
 479         const struct hwmon_channel_info **channels;
 480         u32 *fan_channel_config;
 481         int channel_count = 1;  /* We always have a PWM channel. */
 482         int i;
 483
 484         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 485         if (!ctx)
 486                 return -ENOMEM;
 487
 488         mutex_init(&ctx->lock);
 489
 490         ctx->dev = &pdev->dev;
 491         ctx->pwm = devm_pwm_get(dev, NULL);
 492         if (IS_ERR(ctx->pwm))
 493                 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
 494
 495         platform_set_drvdata(pdev, ctx);
 496
 497         ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 498         if (IS_ERR(ctx->reg_en)) {
 499                 if (PTR_ERR(ctx->reg_en) != -ENODEV)
 500                         return PTR_ERR(ctx->reg_en);
 501
 502                 ctx->reg_en = NULL;
 503         }
 504
 505         pwm_init_state(ctx->pwm, &ctx->pwm_state);
 506
 507         /*
 508          * set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
 509          * long. Check this here to prevent the fan running at a too low
 510          * frequency.
 511          */
 512         if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
 513                 dev_err(dev, "Configured period too big\n");
 514                 return -EINVAL;
 515         }
 516
 517         ctx->enable_mode = pwm_disable_reg_enable;
 518
 519         /*
 520          * Set duty cycle to maximum allowed and enable PWM output as well as
 521          * the regulator. In case of error nothing is changed
 522          */
 523         ret = set_pwm(ctx, MAX_PWM);
 524         if (ret) {
 525                 dev_err(dev, "Failed to configure PWM: %d\n", ret);
 526                 return ret;
 527         }
 528         timer_setup(&ctx->rpm_timer, sample_timer, 0);
 529         ret = devm_add_action_or_reset(dev, pwm_fan_cleanup, ctx);
 530         if (ret)
 531                 return ret;
 532
 533         ctx->tach_count = platform_irq_count(pdev);
 534         if (ctx->tach_count < 0)
 535                 return dev_err_probe(dev, ctx->tach_count,
 536                                      "Could not get number of fan tachometer inputs\n");
 537         dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
 538
 539         if (ctx->tach_count) {
 540                 channel_count++;        /* We also have a FAN channel. */
 541
 542                 ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
 543                                           sizeof(struct pwm_fan_tach),
 544                                           GFP_KERNEL);
 545                 if (!ctx->tachs)
 546                         return -ENOMEM;
 547
 548                 ctx->fan_channel.type = hwmon_fan;
 549                 fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
 550                                                   sizeof(u32), GFP_KERNEL);
 551                 if (!fan_channel_config)
 552                         return -ENOMEM;
 553                 ctx->fan_channel.config = fan_channel_config;
 554         }
 555
 556         channels = devm_kcalloc(dev, channel_count + 1,
 557                                 sizeof(struct hwmon_channel_info *), GFP_KERNEL);
 558         if (!channels)
 559                 return -ENOMEM;
 560
 561         channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE);
 562
 563         for (i = 0; i < ctx->tach_count; i++) {
 564                 struct pwm_fan_tach *tach = &ctx->tachs[i];
 565                 u32 ppr = 2;
 566
 567                 tach->irq = platform_get_irq(pdev, i);
 568                 if (tach->irq == -EPROBE_DEFER)
 569                         return tach->irq;
 570                 if (tach->irq > 0) {
 571                         ret = devm_request_irq(dev, tach->irq, pulse_handler, 0,
 572                                                pdev->name, tach);
 573                         if (ret) {
 574                                 dev_err(dev,
 575                                         "Failed to request interrupt: %d\n",
 576                                         ret);
 577                                 return ret;
 578                         }
 579                 }
 580
 581                 of_property_read_u32_index(dev->of_node,
 582                                            "pulses-per-revolution",
 583                                            i,
 584                                            &ppr);
 585                 tach->pulses_per_revolution = ppr;
 586                 if (!tach->pulses_per_revolution) {
 587                         dev_err(dev, "pulses-per-revolution can't be zero.\n");
 588                         return -EINVAL;
 589                 }
 590
 591                 fan_channel_config[i] = HWMON_F_INPUT;
 592
 593                 dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
 594                         i, tach->irq, tach->pulses_per_revolution);
 595         }
 596
 597         if (ctx->tach_count > 0) {
 598                 ctx->sample_start = ktime_get();
 599                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 600
 601                 channels[1] = &ctx->fan_channel;
 602         }
 603
 604         ctx->info.ops = &pwm_fan_hwmon_ops;
 605         ctx->info.info = channels;
 606
 607         hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
 608                                                      ctx, &ctx->info, NULL);
 609         if (IS_ERR(hwmon)) {
 610                 dev_err(dev, "Failed to register hwmon device\n");
 611                 return PTR_ERR(hwmon);
 612         }
 613
 614         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 615         if (ret)
 616                 return ret;
 617
 618         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 619         if (IS_ENABLED(CONFIG_THERMAL)) {
 620                 cdev = devm_thermal_of_cooling_device_register(dev,
 621                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 622                 if (IS_ERR(cdev)) {
 623                         ret = PTR_ERR(cdev);
 624                         dev_err(dev,
 625                                 "Failed to register pwm-fan as cooling device: %d\n",
 626                                 ret);
 627                         return ret;
 628                 }
 629                 ctx->cdev = cdev;
 630         }
 631
 632         return 0;
 633 }
 634
 635 static void pwm_fan_shutdown(struct platform_device *pdev)
 636 {
 637         struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
 638
 639         pwm_fan_cleanup(ctx);
 640 }
 641
 642 static int pwm_fan_suspend(struct device *dev)
 643 {
 644         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 645
 646         return pwm_fan_power_off(ctx);
 647 }
 648
 649 static int pwm_fan_resume(struct device *dev)
 650 {
 651         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 652
 653         return set_pwm(ctx, ctx->pwm_value);
 654 }
 655
 656 static DEFINE_SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 657
 658 static const struct of_device_id of_pwm_fan_match[] = {
 659         { .compatible = "pwm-fan", },
 660         {},
 661 };
 662 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 663
 664 static struct platform_driver pwm_fan_driver = {
 665         .probe          = pwm_fan_probe,
 666         .shutdown       = pwm_fan_shutdown,
 667         .driver = {
 668                 .name           = "pwm-fan",
 669                 .pm             = pm_sleep_ptr(&pwm_fan_pm),
 670                 .of_match_table = of_pwm_fan_match,
 671         },
 672 };
 673
 674 module_platform_driver(pwm_fan_driver);
 675
 676 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 677 MODULE_ALIAS("platform:pwm-fan");
 678 MODULE_DESCRIPTION("PWM FAN driver");
 679 MODULE_LICENSE("GPL");