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_ctx {
  25         struct mutex lock;
  26         struct pwm_device *pwm;
  27         struct regulator *reg_en;
  28
  29         int irq;
  30         atomic_t pulses;
  31         unsigned int rpm;
  32         u8 pulses_per_revolution;
  33         ktime_t sample_start;
  34         struct timer_list rpm_timer;
  35
  36         unsigned int pwm_value;
  37         unsigned int pwm_fan_state;
  38         unsigned int pwm_fan_max_state;
  39         unsigned int *pwm_fan_cooling_levels;
  40         struct thermal_cooling_device *cdev;
  41
  42         struct hwmon_chip_info info;
  43 };
  44
  45 static const u32 pwm_fan_channel_config_pwm[] = {
  46         HWMON_PWM_INPUT,
  47         0
  48 };
  49
  50 static const struct hwmon_channel_info pwm_fan_channel_pwm = {
  51         .type = hwmon_pwm,
  52         .config = pwm_fan_channel_config_pwm,
  53 };
  54
  55 static const u32 pwm_fan_channel_config_fan[] = {
  56         HWMON_F_INPUT,
  57         0
  58 };
  59
  60 static const struct hwmon_channel_info pwm_fan_channel_fan = {
  61         .type = hwmon_fan,
  62         .config = pwm_fan_channel_config_fan,
  63 };
  64
  65 /* This handler assumes self resetting edge triggered interrupt. */
  66 static irqreturn_t pulse_handler(int irq, void *dev_id)
  67 {
  68         struct pwm_fan_ctx *ctx = dev_id;
  69
  70         atomic_inc(&ctx->pulses);
  71
  72         return IRQ_HANDLED;
  73 }
  74
  75 static void sample_timer(struct timer_list *t)
  76 {
  77         struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
  78         unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
  79         int pulses;
  80
  81         if (delta) {
  82                 pulses = atomic_read(&ctx->pulses);
  83                 atomic_sub(pulses, &ctx->pulses);
  84                 ctx->rpm = (unsigned int)(pulses * 1000 * 60) /
  85                         (ctx->pulses_per_revolution * delta);
  86
  87                 ctx->sample_start = ktime_get();
  88         }
  89
  90         mod_timer(&ctx->rpm_timer, jiffies + HZ);
  91 }
  92
  93 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
  94 {
  95         unsigned long period;
  96         int ret = 0;
  97         struct pwm_state state = { };
  98
  99         mutex_lock(&ctx->lock);
 100         if (ctx->pwm_value == pwm)
 101                 goto exit_set_pwm_err;
 102
 103         pwm_init_state(ctx->pwm, &state);
 104         period = ctx->pwm->args.period;
 105         state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
 106         state.enabled = pwm ? true : false;
 107
 108         ret = pwm_apply_state(ctx->pwm, &state);
 109         if (!ret)
 110                 ctx->pwm_value = pwm;
 111 exit_set_pwm_err:
 112         mutex_unlock(&ctx->lock);
 113         return ret;
 114 }
 115
 116 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
 117 {
 118         int i;
 119
 120         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
 121                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
 122                         break;
 123
 124         ctx->pwm_fan_state = i;
 125 }
 126
 127 static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
 128                          u32 attr, int channel, long val)
 129 {
 130         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 131         int ret;
 132
 133         if (val < 0 || val > MAX_PWM)
 134                 return -EINVAL;
 135
 136         ret = __set_pwm(ctx, val);
 137         if (ret)
 138                 return ret;
 139
 140         pwm_fan_update_state(ctx, val);
 141         return 0;
 142 }
 143
 144 static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
 145                         u32 attr, int channel, long *val)
 146 {
 147         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 148
 149         switch (type) {
 150         case hwmon_pwm:
 151                 *val = ctx->pwm_value;
 152                 return 0;
 153
 154         case hwmon_fan:
 155                 *val = ctx->rpm;
 156                 return 0;
 157
 158         default:
 159                 return -ENOTSUPP;
 160         }
 161 }
 162
 163 static umode_t pwm_fan_is_visible(const void *data,
 164                                   enum hwmon_sensor_types type,
 165                                   u32 attr, int channel)
 166 {
 167         switch (type) {
 168         case hwmon_pwm:
 169                 return 0644;
 170
 171         case hwmon_fan:
 172                 return 0444;
 173
 174         default:
 175                 return 0;
 176         }
 177 }
 178
 179 static const struct hwmon_ops pwm_fan_hwmon_ops = {
 180         .is_visible = pwm_fan_is_visible,
 181         .read = pwm_fan_read,
 182         .write = pwm_fan_write,
 183 };
 184
 185 /* thermal cooling device callbacks */
 186 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 187                                  unsigned long *state)
 188 {
 189         struct pwm_fan_ctx *ctx = cdev->devdata;
 190
 191         if (!ctx)
 192                 return -EINVAL;
 193
 194         *state = ctx->pwm_fan_max_state;
 195
 196         return 0;
 197 }
 198
 199 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 200                                  unsigned long *state)
 201 {
 202         struct pwm_fan_ctx *ctx = cdev->devdata;
 203
 204         if (!ctx)
 205                 return -EINVAL;
 206
 207         *state = ctx->pwm_fan_state;
 208
 209         return 0;
 210 }
 211
 212 static int
 213 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 214 {
 215         struct pwm_fan_ctx *ctx = cdev->devdata;
 216         int ret;
 217
 218         if (!ctx || (state > ctx->pwm_fan_max_state))
 219                 return -EINVAL;
 220
 221         if (state == ctx->pwm_fan_state)
 222                 return 0;
 223
 224         ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 225         if (ret) {
 226                 dev_err(&cdev->device, "Cannot set pwm!\n");
 227                 return ret;
 228         }
 229
 230         ctx->pwm_fan_state = state;
 231
 232         return ret;
 233 }
 234
 235 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 236         .get_max_state = pwm_fan_get_max_state,
 237         .get_cur_state = pwm_fan_get_cur_state,
 238         .set_cur_state = pwm_fan_set_cur_state,
 239 };
 240
 241 static int pwm_fan_of_get_cooling_data(struct device *dev,
 242                                        struct pwm_fan_ctx *ctx)
 243 {
 244         struct device_node *np = dev->of_node;
 245         int num, i, ret;
 246
 247         if (!of_find_property(np, "cooling-levels", NULL))
 248                 return 0;
 249
 250         ret = of_property_count_u32_elems(np, "cooling-levels");
 251         if (ret <= 0) {
 252                 dev_err(dev, "Wrong data!\n");
 253                 return ret ? : -EINVAL;
 254         }
 255
 256         num = ret;
 257         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 258                                                    GFP_KERNEL);
 259         if (!ctx->pwm_fan_cooling_levels)
 260                 return -ENOMEM;
 261
 262         ret = of_property_read_u32_array(np, "cooling-levels",
 263                                          ctx->pwm_fan_cooling_levels, num);
 264         if (ret) {
 265                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 266                 return ret;
 267         }
 268
 269         for (i = 0; i < num; i++) {
 270                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 271                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 272                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 273                         return -EINVAL;
 274                 }
 275         }
 276
 277         ctx->pwm_fan_max_state = num - 1;
 278
 279         return 0;
 280 }
 281
 282 static void pwm_fan_regulator_disable(void *data)
 283 {
 284         regulator_disable(data);
 285 }
 286
 287 static void pwm_fan_pwm_disable(void *__ctx)
 288 {
 289         struct pwm_fan_ctx *ctx = __ctx;
 290         pwm_disable(ctx->pwm);
 291         del_timer_sync(&ctx->rpm_timer);
 292 }
 293
 294 static int pwm_fan_probe(struct platform_device *pdev)
 295 {
 296         struct thermal_cooling_device *cdev;
 297         struct device *dev = &pdev->dev;
 298         struct pwm_fan_ctx *ctx;
 299         struct device *hwmon;
 300         int ret;
 301         struct pwm_state state = { };
 302         int tach_count;
 303         const struct hwmon_channel_info **channels;
 304
 305         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 306         if (!ctx)
 307                 return -ENOMEM;
 308
 309         mutex_init(&ctx->lock);
 310
 311         ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
 312         if (IS_ERR(ctx->pwm))
 313                 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
 314
 315         platform_set_drvdata(pdev, ctx);
 316
 317         ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 318         if (IS_ERR(ctx->reg_en)) {
 319                 if (PTR_ERR(ctx->reg_en) != -ENODEV)
 320                         return PTR_ERR(ctx->reg_en);
 321
 322                 ctx->reg_en = NULL;
 323         } else {
 324                 ret = regulator_enable(ctx->reg_en);
 325                 if (ret) {
 326                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 327                         return ret;
 328                 }
 329                 ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
 330                                                ctx->reg_en);
 331                 if (ret)
 332                         return ret;
 333         }
 334
 335         ctx->pwm_value = MAX_PWM;
 336
 337         pwm_init_state(ctx->pwm, &state);
 338         /*
 339          * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
 340          * long. Check this here to prevent the fan running at a too low
 341          * frequency.
 342          */
 343         if (state.period > ULONG_MAX / MAX_PWM + 1) {
 344                 dev_err(dev, "Configured period too big\n");
 345                 return -EINVAL;
 346         }
 347
 348         /* Set duty cycle to maximum allowed and enable PWM output */
 349         state.duty_cycle = ctx->pwm->args.period - 1;
 350         state.enabled = true;
 351
 352         ret = pwm_apply_state(ctx->pwm, &state);
 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         tach_count = platform_irq_count(pdev);
 363         if (tach_count < 0)
 364                 return dev_err_probe(dev, tach_count,
 365                                      "Could not get number of fan tachometer inputs\n");
 366
 367         channels = devm_kcalloc(dev, tach_count + 2,
 368                                 sizeof(struct hwmon_channel_info *), GFP_KERNEL);
 369         if (!channels)
 370                 return -ENOMEM;
 371
 372         channels[0] = &pwm_fan_channel_pwm;
 373
 374         if (tach_count > 0) {
 375                 u32 ppr = 2;
 376
 377                 ctx->irq = platform_get_irq(pdev, 0);
 378                 if (ctx->irq == -EPROBE_DEFER)
 379                         return ctx->irq;
 380                 if (ctx->irq > 0) {
 381                         ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
 382                                                pdev->name, ctx);
 383                         if (ret) {
 384                                 dev_err(dev,
 385                                         "Failed to request interrupt: %d\n",
 386                                         ret);
 387                                 return ret;
 388                         }
 389                 }
 390
 391                 of_property_read_u32(dev->of_node,
 392                                      "pulses-per-revolution",
 393                                      &ppr);
 394                 ctx->pulses_per_revolution = ppr;
 395                 if (!ctx->pulses_per_revolution) {
 396                         dev_err(dev, "pulses-per-revolution can't be zero.\n");
 397                         return -EINVAL;
 398                 }
 399
 400                 dev_dbg(dev, "tach: irq=%d, pulses_per_revolution=%d\n",
 401                         ctx->irq, ctx->pulses_per_revolution);
 402
 403                 ctx->sample_start = ktime_get();
 404                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 405
 406                 channels[1] = &pwm_fan_channel_fan;
 407         }
 408
 409         ctx->info.ops = &pwm_fan_hwmon_ops;
 410         ctx->info.info = channels;
 411
 412         hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
 413                                                      ctx, &ctx->info, NULL);
 414         if (IS_ERR(hwmon)) {
 415                 dev_err(dev, "Failed to register hwmon device\n");
 416                 return PTR_ERR(hwmon);
 417         }
 418
 419         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 420         if (ret)
 421                 return ret;
 422
 423         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 424         if (IS_ENABLED(CONFIG_THERMAL)) {
 425                 cdev = devm_thermal_of_cooling_device_register(dev,
 426                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 427                 if (IS_ERR(cdev)) {
 428                         ret = PTR_ERR(cdev);
 429                         dev_err(dev,
 430                                 "Failed to register pwm-fan as cooling device: %d\n",
 431                                 ret);
 432                         return ret;
 433                 }
 434                 ctx->cdev = cdev;
 435                 thermal_cdev_update(cdev);
 436         }
 437
 438         return 0;
 439 }
 440
 441 static int pwm_fan_disable(struct device *dev)
 442 {
 443         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 444         struct pwm_args args;
 445         int ret;
 446
 447         pwm_get_args(ctx->pwm, &args);
 448
 449         if (ctx->pwm_value) {
 450                 ret = pwm_config(ctx->pwm, 0, args.period);
 451                 if (ret < 0)
 452                         return ret;
 453
 454                 pwm_disable(ctx->pwm);
 455         }
 456
 457         if (ctx->reg_en) {
 458                 ret = regulator_disable(ctx->reg_en);
 459                 if (ret) {
 460                         dev_err(dev, "Failed to disable fan supply: %d\n", ret);
 461                         return ret;
 462                 }
 463         }
 464
 465         return 0;
 466 }
 467
 468 static void pwm_fan_shutdown(struct platform_device *pdev)
 469 {
 470         pwm_fan_disable(&pdev->dev);
 471 }
 472
 473 #ifdef CONFIG_PM_SLEEP
 474 static int pwm_fan_suspend(struct device *dev)
 475 {
 476         return pwm_fan_disable(dev);
 477 }
 478
 479 static int pwm_fan_resume(struct device *dev)
 480 {
 481         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 482         struct pwm_args pargs;
 483         unsigned long duty;
 484         int ret;
 485
 486         if (ctx->reg_en) {
 487                 ret = regulator_enable(ctx->reg_en);
 488                 if (ret) {
 489                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 490                         return ret;
 491                 }
 492         }
 493
 494         if (ctx->pwm_value == 0)
 495                 return 0;
 496
 497         pwm_get_args(ctx->pwm, &pargs);
 498         duty = DIV_ROUND_UP_ULL(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
 499         ret = pwm_config(ctx->pwm, duty, pargs.period);
 500         if (ret)
 501                 return ret;
 502         return pwm_enable(ctx->pwm);
 503 }
 504 #endif
 505
 506 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 507
 508 static const struct of_device_id of_pwm_fan_match[] = {
 509         { .compatible = "pwm-fan", },
 510         {},
 511 };
 512 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 513
 514 static struct platform_driver pwm_fan_driver = {
 515         .probe          = pwm_fan_probe,
 516         .shutdown       = pwm_fan_shutdown,
 517         .driver = {
 518                 .name           = "pwm-fan",
 519                 .pm             = &pwm_fan_pm,
 520                 .of_match_table = of_pwm_fan_match,
 521         },
 522 };
 523
 524 module_platform_driver(pwm_fan_driver);
 525
 526 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 527 MODULE_ALIAS("platform:pwm-fan");
 528 MODULE_DESCRIPTION("PWM FAN driver");
 529 MODULE_LICENSE("GPL");