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 struct pwm_fan_ctx {
  32         struct mutex lock;
  33         struct pwm_device *pwm;
  34         struct pwm_state pwm_state;
  35         struct regulator *reg_en;
  36
  37         int tach_count;
  38         struct pwm_fan_tach *tachs;
  39         ktime_t sample_start;
  40         struct timer_list rpm_timer;
  41
  42         unsigned int pwm_value;
  43         unsigned int pwm_fan_state;
  44         unsigned int pwm_fan_max_state;
  45         unsigned int *pwm_fan_cooling_levels;
  46         struct thermal_cooling_device *cdev;
  47
  48         struct hwmon_chip_info info;
  49         struct hwmon_channel_info fan_channel;
  50 };
  51
  52 /* This handler assumes self resetting edge triggered interrupt. */
  53 static irqreturn_t pulse_handler(int irq, void *dev_id)
  54 {
  55         struct pwm_fan_tach *tach = dev_id;
  56
  57         atomic_inc(&tach->pulses);
  58
  59         return IRQ_HANDLED;
  60 }
  61
  62 static void sample_timer(struct timer_list *t)
  63 {
  64         struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
  65         unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
  66         int i;
  67
  68         if (delta) {
  69                 for (i = 0; i < ctx->tach_count; i++) {
  70                         struct pwm_fan_tach *tach = &ctx->tachs[i];
  71                         int pulses;
  72
  73                         pulses = atomic_read(&tach->pulses);
  74                         atomic_sub(pulses, &tach->pulses);
  75                         tach->rpm = (unsigned int)(pulses * 1000 * 60) /
  76                                 (tach->pulses_per_revolution * delta);
  77                 }
  78
  79                 ctx->sample_start = ktime_get();
  80         }
  81
  82         mod_timer(&ctx->rpm_timer, jiffies + HZ);
  83 }
  84
  85 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
  86 {
  87         unsigned long period;
  88         int ret = 0;
  89         struct pwm_state *state = &ctx->pwm_state;
  90
  91         mutex_lock(&ctx->lock);
  92         if (ctx->pwm_value == pwm)
  93                 goto exit_set_pwm_err;
  94
  95         period = state->period;
  96         state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
  97         state->enabled = pwm ? true : false;
  98
  99         ret = pwm_apply_state(ctx->pwm, state);
 100         if (!ret)
 101                 ctx->pwm_value = pwm;
 102 exit_set_pwm_err:
 103         mutex_unlock(&ctx->lock);
 104         return ret;
 105 }
 106
 107 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
 108 {
 109         int i;
 110
 111         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
 112                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
 113                         break;
 114
 115         ctx->pwm_fan_state = i;
 116 }
 117
 118 static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
 119                          u32 attr, int channel, long val)
 120 {
 121         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 122         int ret;
 123
 124         if (val < 0 || val > MAX_PWM)
 125                 return -EINVAL;
 126
 127         ret = __set_pwm(ctx, val);
 128         if (ret)
 129                 return ret;
 130
 131         pwm_fan_update_state(ctx, val);
 132         return 0;
 133 }
 134
 135 static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
 136                         u32 attr, int channel, long *val)
 137 {
 138         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 139
 140         switch (type) {
 141         case hwmon_pwm:
 142                 *val = ctx->pwm_value;
 143                 return 0;
 144
 145         case hwmon_fan:
 146                 *val = ctx->tachs[channel].rpm;
 147                 return 0;
 148
 149         default:
 150                 return -ENOTSUPP;
 151         }
 152 }
 153
 154 static umode_t pwm_fan_is_visible(const void *data,
 155                                   enum hwmon_sensor_types type,
 156                                   u32 attr, int channel)
 157 {
 158         switch (type) {
 159         case hwmon_pwm:
 160                 return 0644;
 161
 162         case hwmon_fan:
 163                 return 0444;
 164
 165         default:
 166                 return 0;
 167         }
 168 }
 169
 170 static const struct hwmon_ops pwm_fan_hwmon_ops = {
 171         .is_visible = pwm_fan_is_visible,
 172         .read = pwm_fan_read,
 173         .write = pwm_fan_write,
 174 };
 175
 176 /* thermal cooling device callbacks */
 177 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 178                                  unsigned long *state)
 179 {
 180         struct pwm_fan_ctx *ctx = cdev->devdata;
 181
 182         if (!ctx)
 183                 return -EINVAL;
 184
 185         *state = ctx->pwm_fan_max_state;
 186
 187         return 0;
 188 }
 189
 190 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 191                                  unsigned long *state)
 192 {
 193         struct pwm_fan_ctx *ctx = cdev->devdata;
 194
 195         if (!ctx)
 196                 return -EINVAL;
 197
 198         *state = ctx->pwm_fan_state;
 199
 200         return 0;
 201 }
 202
 203 static int
 204 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 205 {
 206         struct pwm_fan_ctx *ctx = cdev->devdata;
 207         int ret;
 208
 209         if (!ctx || (state > ctx->pwm_fan_max_state))
 210                 return -EINVAL;
 211
 212         if (state == ctx->pwm_fan_state)
 213                 return 0;
 214
 215         ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 216         if (ret) {
 217                 dev_err(&cdev->device, "Cannot set pwm!\n");
 218                 return ret;
 219         }
 220
 221         ctx->pwm_fan_state = state;
 222
 223         return ret;
 224 }
 225
 226 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 227         .get_max_state = pwm_fan_get_max_state,
 228         .get_cur_state = pwm_fan_get_cur_state,
 229         .set_cur_state = pwm_fan_set_cur_state,
 230 };
 231
 232 static int pwm_fan_of_get_cooling_data(struct device *dev,
 233                                        struct pwm_fan_ctx *ctx)
 234 {
 235         struct device_node *np = dev->of_node;
 236         int num, i, ret;
 237
 238         if (!of_find_property(np, "cooling-levels", NULL))
 239                 return 0;
 240
 241         ret = of_property_count_u32_elems(np, "cooling-levels");
 242         if (ret <= 0) {
 243                 dev_err(dev, "Wrong data!\n");
 244                 return ret ? : -EINVAL;
 245         }
 246
 247         num = ret;
 248         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 249                                                    GFP_KERNEL);
 250         if (!ctx->pwm_fan_cooling_levels)
 251                 return -ENOMEM;
 252
 253         ret = of_property_read_u32_array(np, "cooling-levels",
 254                                          ctx->pwm_fan_cooling_levels, num);
 255         if (ret) {
 256                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 257                 return ret;
 258         }
 259
 260         for (i = 0; i < num; i++) {
 261                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 262                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 263                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 264                         return -EINVAL;
 265                 }
 266         }
 267
 268         ctx->pwm_fan_max_state = num - 1;
 269
 270         return 0;
 271 }
 272
 273 static void pwm_fan_regulator_disable(void *data)
 274 {
 275         regulator_disable(data);
 276 }
 277
 278 static void pwm_fan_pwm_disable(void *__ctx)
 279 {
 280         struct pwm_fan_ctx *ctx = __ctx;
 281
 282         ctx->pwm_state.enabled = false;
 283         pwm_apply_state(ctx->pwm, &ctx->pwm_state);
 284         del_timer_sync(&ctx->rpm_timer);
 285 }
 286
 287 static int pwm_fan_probe(struct platform_device *pdev)
 288 {
 289         struct thermal_cooling_device *cdev;
 290         struct device *dev = &pdev->dev;
 291         struct pwm_fan_ctx *ctx;
 292         struct device *hwmon;
 293         int ret;
 294         const struct hwmon_channel_info **channels;
 295         u32 *fan_channel_config;
 296         int channel_count = 1;  /* We always have a PWM channel. */
 297         int i;
 298
 299         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 300         if (!ctx)
 301                 return -ENOMEM;
 302
 303         mutex_init(&ctx->lock);
 304
 305         ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
 306         if (IS_ERR(ctx->pwm))
 307                 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
 308
 309         platform_set_drvdata(pdev, ctx);
 310
 311         ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 312         if (IS_ERR(ctx->reg_en)) {
 313                 if (PTR_ERR(ctx->reg_en) != -ENODEV)
 314                         return PTR_ERR(ctx->reg_en);
 315
 316                 ctx->reg_en = NULL;
 317         } else {
 318                 ret = regulator_enable(ctx->reg_en);
 319                 if (ret) {
 320                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 321                         return ret;
 322                 }
 323                 ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
 324                                                ctx->reg_en);
 325                 if (ret)
 326                         return ret;
 327         }
 328
 329         pwm_init_state(ctx->pwm, &ctx->pwm_state);
 330
 331         /*
 332          * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
 333          * long. Check this here to prevent the fan running at a too low
 334          * frequency.
 335          */
 336         if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
 337                 dev_err(dev, "Configured period too big\n");
 338                 return -EINVAL;
 339         }
 340
 341         /* Set duty cycle to maximum allowed and enable PWM output */
 342         ret = __set_pwm(ctx, MAX_PWM);
 343         if (ret) {
 344                 dev_err(dev, "Failed to configure PWM: %d\n", ret);
 345                 return ret;
 346         }
 347         timer_setup(&ctx->rpm_timer, sample_timer, 0);
 348         ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
 349         if (ret)
 350                 return ret;
 351
 352         ctx->tach_count = platform_irq_count(pdev);
 353         if (ctx->tach_count < 0)
 354                 return dev_err_probe(dev, ctx->tach_count,
 355                                      "Could not get number of fan tachometer inputs\n");
 356         dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
 357
 358         if (ctx->tach_count) {
 359                 channel_count++;        /* We also have a FAN channel. */
 360
 361                 ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
 362                                           sizeof(struct pwm_fan_tach),
 363                                           GFP_KERNEL);
 364                 if (!ctx->tachs)
 365                         return -ENOMEM;
 366
 367                 ctx->fan_channel.type = hwmon_fan;
 368                 fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
 369                                                   sizeof(u32), GFP_KERNEL);
 370                 if (!fan_channel_config)
 371                         return -ENOMEM;
 372                 ctx->fan_channel.config = fan_channel_config;
 373         }
 374
 375         channels = devm_kcalloc(dev, channel_count + 1,
 376                                 sizeof(struct hwmon_channel_info *), GFP_KERNEL);
 377         if (!channels)
 378                 return -ENOMEM;
 379
 380         channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT);
 381
 382         for (i = 0; i < ctx->tach_count; i++) {
 383                 struct pwm_fan_tach *tach = &ctx->tachs[i];
 384                 u32 ppr = 2;
 385
 386                 tach->irq = platform_get_irq(pdev, i);
 387                 if (tach->irq == -EPROBE_DEFER)
 388                         return tach->irq;
 389                 if (tach->irq > 0) {
 390                         ret = devm_request_irq(dev, tach->irq, pulse_handler, 0,
 391                                                pdev->name, tach);
 392                         if (ret) {
 393                                 dev_err(dev,
 394                                         "Failed to request interrupt: %d\n",
 395                                         ret);
 396                                 return ret;
 397                         }
 398                 }
 399
 400                 of_property_read_u32_index(dev->of_node,
 401                                            "pulses-per-revolution",
 402                                            i,
 403                                            &ppr);
 404                 tach->pulses_per_revolution = ppr;
 405                 if (!tach->pulses_per_revolution) {
 406                         dev_err(dev, "pulses-per-revolution can't be zero.\n");
 407                         return -EINVAL;
 408                 }
 409
 410                 fan_channel_config[i] = HWMON_F_INPUT;
 411
 412                 dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
 413                         i, tach->irq, tach->pulses_per_revolution);
 414         }
 415
 416         if (ctx->tach_count > 0) {
 417                 ctx->sample_start = ktime_get();
 418                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 419
 420                 channels[1] = &ctx->fan_channel;
 421         }
 422
 423         ctx->info.ops = &pwm_fan_hwmon_ops;
 424         ctx->info.info = channels;
 425
 426         hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
 427                                                      ctx, &ctx->info, NULL);
 428         if (IS_ERR(hwmon)) {
 429                 dev_err(dev, "Failed to register hwmon device\n");
 430                 return PTR_ERR(hwmon);
 431         }
 432
 433         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 434         if (ret)
 435                 return ret;
 436
 437         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 438         if (IS_ENABLED(CONFIG_THERMAL)) {
 439                 cdev = devm_thermal_of_cooling_device_register(dev,
 440                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 441                 if (IS_ERR(cdev)) {
 442                         ret = PTR_ERR(cdev);
 443                         dev_err(dev,
 444                                 "Failed to register pwm-fan as cooling device: %d\n",
 445                                 ret);
 446                         return ret;
 447                 }
 448                 ctx->cdev = cdev;
 449         }
 450
 451         return 0;
 452 }
 453
 454 static int pwm_fan_disable(struct device *dev)
 455 {
 456         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 457         int ret;
 458
 459         if (ctx->pwm_value) {
 460                 /* keep ctx->pwm_state unmodified for pwm_fan_resume() */
 461                 struct pwm_state state = ctx->pwm_state;
 462
 463                 state.duty_cycle = 0;
 464                 state.enabled = false;
 465                 ret = pwm_apply_state(ctx->pwm, &state);
 466                 if (ret < 0)
 467                         return ret;
 468         }
 469
 470         if (ctx->reg_en) {
 471                 ret = regulator_disable(ctx->reg_en);
 472                 if (ret) {
 473                         dev_err(dev, "Failed to disable fan supply: %d\n", ret);
 474                         return ret;
 475                 }
 476         }
 477
 478         return 0;
 479 }
 480
 481 static void pwm_fan_shutdown(struct platform_device *pdev)
 482 {
 483         pwm_fan_disable(&pdev->dev);
 484 }
 485
 486 #ifdef CONFIG_PM_SLEEP
 487 static int pwm_fan_suspend(struct device *dev)
 488 {
 489         return pwm_fan_disable(dev);
 490 }
 491
 492 static int pwm_fan_resume(struct device *dev)
 493 {
 494         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 495         int ret;
 496
 497         if (ctx->reg_en) {
 498                 ret = regulator_enable(ctx->reg_en);
 499                 if (ret) {
 500                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 501                         return ret;
 502                 }
 503         }
 504
 505         if (ctx->pwm_value == 0)
 506                 return 0;
 507
 508         return pwm_apply_state(ctx->pwm, &ctx->pwm_state);
 509 }
 510 #endif
 511
 512 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 513
 514 static const struct of_device_id of_pwm_fan_match[] = {
 515         { .compatible = "pwm-fan", },
 516         {},
 517 };
 518 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 519
 520 static struct platform_driver pwm_fan_driver = {
 521         .probe          = pwm_fan_probe,
 522         .shutdown       = pwm_fan_shutdown,
 523         .driver = {
 524                 .name           = "pwm-fan",
 525                 .pm             = &pwm_fan_pm,
 526                 .of_match_table = of_pwm_fan_match,
 527         },
 528 };
 529
 530 module_platform_driver(pwm_fan_driver);
 531
 532 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 533 MODULE_ALIAS("platform:pwm-fan");
 534 MODULE_DESCRIPTION("PWM FAN driver");
 535 MODULE_LICENSE("GPL");