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 static const u32 pwm_fan_channel_config_pwm[] = {
  53         HWMON_PWM_INPUT,
  54         0
  55 };
  56
  57 static const struct hwmon_channel_info pwm_fan_channel_pwm = {
  58         .type = hwmon_pwm,
  59         .config = pwm_fan_channel_config_pwm,
  60 };
  61
  62 /* This handler assumes self resetting edge triggered interrupt. */
  63 static irqreturn_t pulse_handler(int irq, void *dev_id)
  64 {
  65         struct pwm_fan_tach *tach = dev_id;
  66
  67         atomic_inc(&tach->pulses);
  68
  69         return IRQ_HANDLED;
  70 }
  71
  72 static void sample_timer(struct timer_list *t)
  73 {
  74         struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
  75         unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
  76         int i;
  77
  78         if (delta) {
  79                 for (i = 0; i < ctx->tach_count; i++) {
  80                         struct pwm_fan_tach *tach = &ctx->tachs[i];
  81                         int pulses;
  82
  83                         pulses = atomic_read(&tach->pulses);
  84                         atomic_sub(pulses, &tach->pulses);
  85                         tach->rpm = (unsigned int)(pulses * 1000 * 60) /
  86                                 (tach->pulses_per_revolution * delta);
  87                 }
  88
  89                 ctx->sample_start = ktime_get();
  90         }
  91
  92         mod_timer(&ctx->rpm_timer, jiffies + HZ);
  93 }
  94
  95 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
  96 {
  97         unsigned long period;
  98         int ret = 0;
  99         struct pwm_state *state = &ctx->pwm_state;
 100
 101         mutex_lock(&ctx->lock);
 102         if (ctx->pwm_value == pwm)
 103                 goto exit_set_pwm_err;
 104
 105         period = state->period;
 106         state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
 107         state->enabled = pwm ? true : false;
 108
 109         ret = pwm_apply_state(ctx->pwm, state);
 110         if (!ret)
 111                 ctx->pwm_value = pwm;
 112 exit_set_pwm_err:
 113         mutex_unlock(&ctx->lock);
 114         return ret;
 115 }
 116
 117 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
 118 {
 119         int i;
 120
 121         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
 122                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
 123                         break;
 124
 125         ctx->pwm_fan_state = i;
 126 }
 127
 128 static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
 129                          u32 attr, int channel, long val)
 130 {
 131         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 132         int ret;
 133
 134         if (val < 0 || val > MAX_PWM)
 135                 return -EINVAL;
 136
 137         ret = __set_pwm(ctx, val);
 138         if (ret)
 139                 return ret;
 140
 141         pwm_fan_update_state(ctx, val);
 142         return 0;
 143 }
 144
 145 static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
 146                         u32 attr, int channel, long *val)
 147 {
 148         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 149
 150         switch (type) {
 151         case hwmon_pwm:
 152                 *val = ctx->pwm_value;
 153                 return 0;
 154
 155         case hwmon_fan:
 156                 *val = ctx->tachs[channel].rpm;
 157                 return 0;
 158
 159         default:
 160                 return -ENOTSUPP;
 161         }
 162 }
 163
 164 static umode_t pwm_fan_is_visible(const void *data,
 165                                   enum hwmon_sensor_types type,
 166                                   u32 attr, int channel)
 167 {
 168         switch (type) {
 169         case hwmon_pwm:
 170                 return 0644;
 171
 172         case hwmon_fan:
 173                 return 0444;
 174
 175         default:
 176                 return 0;
 177         }
 178 }
 179
 180 static const struct hwmon_ops pwm_fan_hwmon_ops = {
 181         .is_visible = pwm_fan_is_visible,
 182         .read = pwm_fan_read,
 183         .write = pwm_fan_write,
 184 };
 185
 186 /* thermal cooling device callbacks */
 187 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 188                                  unsigned long *state)
 189 {
 190         struct pwm_fan_ctx *ctx = cdev->devdata;
 191
 192         if (!ctx)
 193                 return -EINVAL;
 194
 195         *state = ctx->pwm_fan_max_state;
 196
 197         return 0;
 198 }
 199
 200 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 201                                  unsigned long *state)
 202 {
 203         struct pwm_fan_ctx *ctx = cdev->devdata;
 204
 205         if (!ctx)
 206                 return -EINVAL;
 207
 208         *state = ctx->pwm_fan_state;
 209
 210         return 0;
 211 }
 212
 213 static int
 214 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 215 {
 216         struct pwm_fan_ctx *ctx = cdev->devdata;
 217         int ret;
 218
 219         if (!ctx || (state > ctx->pwm_fan_max_state))
 220                 return -EINVAL;
 221
 222         if (state == ctx->pwm_fan_state)
 223                 return 0;
 224
 225         ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 226         if (ret) {
 227                 dev_err(&cdev->device, "Cannot set pwm!\n");
 228                 return ret;
 229         }
 230
 231         ctx->pwm_fan_state = state;
 232
 233         return ret;
 234 }
 235
 236 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 237         .get_max_state = pwm_fan_get_max_state,
 238         .get_cur_state = pwm_fan_get_cur_state,
 239         .set_cur_state = pwm_fan_set_cur_state,
 240 };
 241
 242 static int pwm_fan_of_get_cooling_data(struct device *dev,
 243                                        struct pwm_fan_ctx *ctx)
 244 {
 245         struct device_node *np = dev->of_node;
 246         int num, i, ret;
 247
 248         if (!of_find_property(np, "cooling-levels", NULL))
 249                 return 0;
 250
 251         ret = of_property_count_u32_elems(np, "cooling-levels");
 252         if (ret <= 0) {
 253                 dev_err(dev, "Wrong data!\n");
 254                 return ret ? : -EINVAL;
 255         }
 256
 257         num = ret;
 258         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 259                                                    GFP_KERNEL);
 260         if (!ctx->pwm_fan_cooling_levels)
 261                 return -ENOMEM;
 262
 263         ret = of_property_read_u32_array(np, "cooling-levels",
 264                                          ctx->pwm_fan_cooling_levels, num);
 265         if (ret) {
 266                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 267                 return ret;
 268         }
 269
 270         for (i = 0; i < num; i++) {
 271                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 272                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 273                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 274                         return -EINVAL;
 275                 }
 276         }
 277
 278         ctx->pwm_fan_max_state = num - 1;
 279
 280         return 0;
 281 }
 282
 283 static void pwm_fan_regulator_disable(void *data)
 284 {
 285         regulator_disable(data);
 286 }
 287
 288 static void pwm_fan_pwm_disable(void *__ctx)
 289 {
 290         struct pwm_fan_ctx *ctx = __ctx;
 291
 292         ctx->pwm_state.enabled = false;
 293         pwm_apply_state(ctx->pwm, &ctx->pwm_state);
 294         del_timer_sync(&ctx->rpm_timer);
 295 }
 296
 297 static int pwm_fan_probe(struct platform_device *pdev)
 298 {
 299         struct thermal_cooling_device *cdev;
 300         struct device *dev = &pdev->dev;
 301         struct pwm_fan_ctx *ctx;
 302         struct device *hwmon;
 303         int ret;
 304         const struct hwmon_channel_info **channels;
 305         u32 *fan_channel_config;
 306         int channel_count = 1;  /* We always have a PWM channel. */
 307         int i;
 308
 309         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 310         if (!ctx)
 311                 return -ENOMEM;
 312
 313         mutex_init(&ctx->lock);
 314
 315         ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
 316         if (IS_ERR(ctx->pwm))
 317                 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
 318
 319         platform_set_drvdata(pdev, ctx);
 320
 321         ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 322         if (IS_ERR(ctx->reg_en)) {
 323                 if (PTR_ERR(ctx->reg_en) != -ENODEV)
 324                         return PTR_ERR(ctx->reg_en);
 325
 326                 ctx->reg_en = NULL;
 327         } else {
 328                 ret = regulator_enable(ctx->reg_en);
 329                 if (ret) {
 330                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 331                         return ret;
 332                 }
 333                 ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
 334                                                ctx->reg_en);
 335                 if (ret)
 336                         return ret;
 337         }
 338
 339         pwm_init_state(ctx->pwm, &ctx->pwm_state);
 340
 341         /*
 342          * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
 343          * long. Check this here to prevent the fan running at a too low
 344          * frequency.
 345          */
 346         if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
 347                 dev_err(dev, "Configured period too big\n");
 348                 return -EINVAL;
 349         }
 350
 351         /* Set duty cycle to maximum allowed and enable PWM output */
 352         ret = __set_pwm(ctx, MAX_PWM);
 353         if (ret) {
 354                 dev_err(dev, "Failed to configure PWM: %d\n", ret);
 355                 return ret;
 356         }
 357         timer_setup(&ctx->rpm_timer, sample_timer, 0);
 358         ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
 359         if (ret)
 360                 return ret;
 361
 362         ctx->tach_count = platform_irq_count(pdev);
 363         if (ctx->tach_count < 0)
 364                 return dev_err_probe(dev, ctx->tach_count,
 365                                      "Could not get number of fan tachometer inputs\n");
 366         dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
 367
 368         if (ctx->tach_count) {
 369                 channel_count++;        /* We also have a FAN channel. */
 370
 371                 ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
 372                                           sizeof(struct pwm_fan_tach),
 373                                           GFP_KERNEL);
 374                 if (!ctx->tachs)
 375                         return -ENOMEM;
 376
 377                 ctx->fan_channel.type = hwmon_fan;
 378                 fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
 379                                                   sizeof(u32), GFP_KERNEL);
 380                 if (!fan_channel_config)
 381                         return -ENOMEM;
 382                 ctx->fan_channel.config = fan_channel_config;
 383         }
 384
 385         channels = devm_kcalloc(dev, channel_count + 1,
 386                                 sizeof(struct hwmon_channel_info *), GFP_KERNEL);
 387         if (!channels)
 388                 return -ENOMEM;
 389
 390         channels[0] = &pwm_fan_channel_pwm;
 391
 392         for (i = 0; i < ctx->tach_count; i++) {
 393                 struct pwm_fan_tach *tach = &ctx->tachs[i];
 394                 u32 ppr = 2;
 395
 396                 tach->irq = platform_get_irq(pdev, i);
 397                 if (tach->irq == -EPROBE_DEFER)
 398                         return tach->irq;
 399                 if (tach->irq > 0) {
 400                         ret = devm_request_irq(dev, tach->irq, pulse_handler, 0,
 401                                                pdev->name, tach);
 402                         if (ret) {
 403                                 dev_err(dev,
 404                                         "Failed to request interrupt: %d\n",
 405                                         ret);
 406                                 return ret;
 407                         }
 408                 }
 409
 410                 of_property_read_u32_index(dev->of_node,
 411                                            "pulses-per-revolution",
 412                                            i,
 413                                            &ppr);
 414                 tach->pulses_per_revolution = ppr;
 415                 if (!tach->pulses_per_revolution) {
 416                         dev_err(dev, "pulses-per-revolution can't be zero.\n");
 417                         return -EINVAL;
 418                 }
 419
 420                 fan_channel_config[i] = HWMON_F_INPUT;
 421
 422                 dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
 423                         i, tach->irq, tach->pulses_per_revolution);
 424         }
 425
 426         if (ctx->tach_count > 0) {
 427                 ctx->sample_start = ktime_get();
 428                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 429
 430                 channels[1] = &ctx->fan_channel;
 431         }
 432
 433         ctx->info.ops = &pwm_fan_hwmon_ops;
 434         ctx->info.info = channels;
 435
 436         hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
 437                                                      ctx, &ctx->info, NULL);
 438         if (IS_ERR(hwmon)) {
 439                 dev_err(dev, "Failed to register hwmon device\n");
 440                 return PTR_ERR(hwmon);
 441         }
 442
 443         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 444         if (ret)
 445                 return ret;
 446
 447         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 448         if (IS_ENABLED(CONFIG_THERMAL)) {
 449                 cdev = devm_thermal_of_cooling_device_register(dev,
 450                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 451                 if (IS_ERR(cdev)) {
 452                         ret = PTR_ERR(cdev);
 453                         dev_err(dev,
 454                                 "Failed to register pwm-fan as cooling device: %d\n",
 455                                 ret);
 456                         return ret;
 457                 }
 458                 ctx->cdev = cdev;
 459         }
 460
 461         return 0;
 462 }
 463
 464 static int pwm_fan_disable(struct device *dev)
 465 {
 466         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 467         int ret;
 468
 469         if (ctx->pwm_value) {
 470                 /* keep ctx->pwm_state unmodified for pwm_fan_resume() */
 471                 struct pwm_state state = ctx->pwm_state;
 472
 473                 state.duty_cycle = 0;
 474                 state.enabled = false;
 475                 ret = pwm_apply_state(ctx->pwm, &state);
 476                 if (ret < 0)
 477                         return ret;
 478         }
 479
 480         if (ctx->reg_en) {
 481                 ret = regulator_disable(ctx->reg_en);
 482                 if (ret) {
 483                         dev_err(dev, "Failed to disable fan supply: %d\n", ret);
 484                         return ret;
 485                 }
 486         }
 487
 488         return 0;
 489 }
 490
 491 static void pwm_fan_shutdown(struct platform_device *pdev)
 492 {
 493         pwm_fan_disable(&pdev->dev);
 494 }
 495
 496 #ifdef CONFIG_PM_SLEEP
 497 static int pwm_fan_suspend(struct device *dev)
 498 {
 499         return pwm_fan_disable(dev);
 500 }
 501
 502 static int pwm_fan_resume(struct device *dev)
 503 {
 504         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 505         int ret;
 506
 507         if (ctx->reg_en) {
 508                 ret = regulator_enable(ctx->reg_en);
 509                 if (ret) {
 510                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 511                         return ret;
 512                 }
 513         }
 514
 515         if (ctx->pwm_value == 0)
 516                 return 0;
 517
 518         return pwm_apply_state(ctx->pwm, &ctx->pwm_state);
 519 }
 520 #endif
 521
 522 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 523
 524 static const struct of_device_id of_pwm_fan_match[] = {
 525         { .compatible = "pwm-fan", },
 526         {},
 527 };
 528 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 529
 530 static struct platform_driver pwm_fan_driver = {
 531         .probe          = pwm_fan_probe,
 532         .shutdown       = pwm_fan_shutdown,
 533         .driver = {
 534                 .name           = "pwm-fan",
 535                 .pm             = &pwm_fan_pm,
 536                 .of_match_table = of_pwm_fan_match,
 537         },
 538 };
 539
 540 module_platform_driver(pwm_fan_driver);
 541
 542 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 543 MODULE_ALIAS("platform:pwm-fan");
 544 MODULE_DESCRIPTION("PWM FAN driver");
 545 MODULE_LICENSE("GPL");