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/hwmon-sysfs.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/of.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/pwm.h>
  18 #include <linux/regulator/consumer.h>
  19 #include <linux/sysfs.h>
  20 #include <linux/thermal.h>
  21 #include <linux/timer.h>
  22
  23 #define MAX_PWM 255
  24
  25 struct pwm_fan_ctx {
  26         struct mutex lock;
  27         struct pwm_device *pwm;
  28         struct regulator *reg_en;
  29
  30         int irq;
  31         atomic_t pulses;
  32         unsigned int rpm;
  33         u8 pulses_per_revolution;
  34         ktime_t sample_start;
  35         struct timer_list rpm_timer;
  36
  37         unsigned int pwm_value;
  38         unsigned int pwm_fan_state;
  39         unsigned int pwm_fan_max_state;
  40         unsigned int *pwm_fan_cooling_levels;
  41         struct thermal_cooling_device *cdev;
  42 };
  43
  44 /* This handler assumes self resetting edge triggered interrupt. */
  45 static irqreturn_t pulse_handler(int irq, void *dev_id)
  46 {
  47         struct pwm_fan_ctx *ctx = dev_id;
  48
  49         atomic_inc(&ctx->pulses);
  50
  51         return IRQ_HANDLED;
  52 }
  53
  54 static void sample_timer(struct timer_list *t)
  55 {
  56         struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
  57         unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
  58         int pulses;
  59
  60         if (delta) {
  61                 pulses = atomic_read(&ctx->pulses);
  62                 atomic_sub(pulses, &ctx->pulses);
  63                 ctx->rpm = (unsigned int)(pulses * 1000 * 60) /
  64                         (ctx->pulses_per_revolution * delta);
  65
  66                 ctx->sample_start = ktime_get();
  67         }
  68
  69         mod_timer(&ctx->rpm_timer, jiffies + HZ);
  70 }
  71
  72 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
  73 {
  74         unsigned long period;
  75         int ret = 0;
  76         struct pwm_state state = { };
  77
  78         mutex_lock(&ctx->lock);
  79         if (ctx->pwm_value == pwm)
  80                 goto exit_set_pwm_err;
  81
  82         pwm_init_state(ctx->pwm, &state);
  83         period = ctx->pwm->args.period;
  84         state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
  85         state.enabled = pwm ? true : false;
  86
  87         ret = pwm_apply_state(ctx->pwm, &state);
  88         if (!ret)
  89                 ctx->pwm_value = pwm;
  90 exit_set_pwm_err:
  91         mutex_unlock(&ctx->lock);
  92         return ret;
  93 }
  94
  95 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
  96 {
  97         int i;
  98
  99         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
 100                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
 101                         break;
 102
 103         ctx->pwm_fan_state = i;
 104 }
 105
 106 static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
 107                          const char *buf, size_t count)
 108 {
 109         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 110         unsigned long pwm;
 111         int ret;
 112
 113         if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
 114                 return -EINVAL;
 115
 116         ret = __set_pwm(ctx, pwm);
 117         if (ret)
 118                 return ret;
 119
 120         pwm_fan_update_state(ctx, pwm);
 121         return count;
 122 }
 123
 124 static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
 125                         char *buf)
 126 {
 127         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 128
 129         return sprintf(buf, "%u\n", ctx->pwm_value);
 130 }
 131
 132 static ssize_t rpm_show(struct device *dev,
 133                         struct device_attribute *attr, char *buf)
 134 {
 135         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 136
 137         return sprintf(buf, "%u\n", ctx->rpm);
 138 }
 139
 140 static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
 141 static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
 142
 143 static struct attribute *pwm_fan_attrs[] = {
 144         &sensor_dev_attr_pwm1.dev_attr.attr,
 145         &sensor_dev_attr_fan1_input.dev_attr.attr,
 146         NULL,
 147 };
 148
 149 static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
 150                                      int n)
 151 {
 152         struct device *dev = container_of(kobj, struct device, kobj);
 153         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 154
 155         /* Hide fan_input in case no interrupt is available  */
 156         if (n == 1 && ctx->irq <= 0)
 157                 return 0;
 158
 159         return a->mode;
 160 }
 161
 162 static const struct attribute_group pwm_fan_group = {
 163         .attrs = pwm_fan_attrs,
 164         .is_visible = pwm_fan_attrs_visible,
 165 };
 166
 167 static const struct attribute_group *pwm_fan_groups[] = {
 168         &pwm_fan_group,
 169         NULL,
 170 };
 171
 172 /* thermal cooling device callbacks */
 173 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 174                                  unsigned long *state)
 175 {
 176         struct pwm_fan_ctx *ctx = cdev->devdata;
 177
 178         if (!ctx)
 179                 return -EINVAL;
 180
 181         *state = ctx->pwm_fan_max_state;
 182
 183         return 0;
 184 }
 185
 186 static int pwm_fan_get_cur_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_state;
 195
 196         return 0;
 197 }
 198
 199 static int
 200 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 201 {
 202         struct pwm_fan_ctx *ctx = cdev->devdata;
 203         int ret;
 204
 205         if (!ctx || (state > ctx->pwm_fan_max_state))
 206                 return -EINVAL;
 207
 208         if (state == ctx->pwm_fan_state)
 209                 return 0;
 210
 211         ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 212         if (ret) {
 213                 dev_err(&cdev->device, "Cannot set pwm!\n");
 214                 return ret;
 215         }
 216
 217         ctx->pwm_fan_state = state;
 218
 219         return ret;
 220 }
 221
 222 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 223         .get_max_state = pwm_fan_get_max_state,
 224         .get_cur_state = pwm_fan_get_cur_state,
 225         .set_cur_state = pwm_fan_set_cur_state,
 226 };
 227
 228 static int pwm_fan_of_get_cooling_data(struct device *dev,
 229                                        struct pwm_fan_ctx *ctx)
 230 {
 231         struct device_node *np = dev->of_node;
 232         int num, i, ret;
 233
 234         if (!of_find_property(np, "cooling-levels", NULL))
 235                 return 0;
 236
 237         ret = of_property_count_u32_elems(np, "cooling-levels");
 238         if (ret <= 0) {
 239                 dev_err(dev, "Wrong data!\n");
 240                 return ret ? : -EINVAL;
 241         }
 242
 243         num = ret;
 244         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 245                                                    GFP_KERNEL);
 246         if (!ctx->pwm_fan_cooling_levels)
 247                 return -ENOMEM;
 248
 249         ret = of_property_read_u32_array(np, "cooling-levels",
 250                                          ctx->pwm_fan_cooling_levels, num);
 251         if (ret) {
 252                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 253                 return ret;
 254         }
 255
 256         for (i = 0; i < num; i++) {
 257                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 258                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 259                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 260                         return -EINVAL;
 261                 }
 262         }
 263
 264         ctx->pwm_fan_max_state = num - 1;
 265
 266         return 0;
 267 }
 268
 269 static void pwm_fan_regulator_disable(void *data)
 270 {
 271         regulator_disable(data);
 272 }
 273
 274 static void pwm_fan_pwm_disable(void *__ctx)
 275 {
 276         struct pwm_fan_ctx *ctx = __ctx;
 277         pwm_disable(ctx->pwm);
 278         del_timer_sync(&ctx->rpm_timer);
 279 }
 280
 281 static int pwm_fan_probe(struct platform_device *pdev)
 282 {
 283         struct thermal_cooling_device *cdev;
 284         struct device *dev = &pdev->dev;
 285         struct pwm_fan_ctx *ctx;
 286         struct device *hwmon;
 287         int ret;
 288         struct pwm_state state = { };
 289         u32 ppr = 2;
 290
 291         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 292         if (!ctx)
 293                 return -ENOMEM;
 294
 295         mutex_init(&ctx->lock);
 296
 297         ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
 298         if (IS_ERR(ctx->pwm))
 299                 return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
 300
 301         platform_set_drvdata(pdev, ctx);
 302
 303         ctx->irq = platform_get_irq_optional(pdev, 0);
 304         if (ctx->irq == -EPROBE_DEFER)
 305                 return ctx->irq;
 306
 307         ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 308         if (IS_ERR(ctx->reg_en)) {
 309                 if (PTR_ERR(ctx->reg_en) != -ENODEV)
 310                         return PTR_ERR(ctx->reg_en);
 311
 312                 ctx->reg_en = NULL;
 313         } else {
 314                 ret = regulator_enable(ctx->reg_en);
 315                 if (ret) {
 316                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 317                         return ret;
 318                 }
 319                 ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
 320                                                ctx->reg_en);
 321                 if (ret)
 322                         return ret;
 323         }
 324
 325         ctx->pwm_value = MAX_PWM;
 326
 327         /* Set duty cycle to maximum allowed and enable PWM output */
 328         pwm_init_state(ctx->pwm, &state);
 329         state.duty_cycle = ctx->pwm->args.period - 1;
 330         state.enabled = true;
 331
 332         ret = pwm_apply_state(ctx->pwm, &state);
 333         if (ret) {
 334                 dev_err(dev, "Failed to configure PWM: %d\n", ret);
 335                 return ret;
 336         }
 337         timer_setup(&ctx->rpm_timer, sample_timer, 0);
 338         ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
 339         if (ret)
 340                 return ret;
 341
 342         of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);
 343         ctx->pulses_per_revolution = ppr;
 344         if (!ctx->pulses_per_revolution) {
 345                 dev_err(dev, "pulses-per-revolution can't be zero.\n");
 346                 return -EINVAL;
 347         }
 348
 349         if (ctx->irq > 0) {
 350                 ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
 351                                        pdev->name, ctx);
 352                 if (ret) {
 353                         dev_err(dev, "Failed to request interrupt: %d\n", ret);
 354                         return ret;
 355                 }
 356                 ctx->sample_start = ktime_get();
 357                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 358         }
 359
 360         hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
 361                                                        ctx, pwm_fan_groups);
 362         if (IS_ERR(hwmon)) {
 363                 dev_err(dev, "Failed to register hwmon device\n");
 364                 return PTR_ERR(hwmon);
 365         }
 366
 367         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 368         if (ret)
 369                 return ret;
 370
 371         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 372         if (IS_ENABLED(CONFIG_THERMAL)) {
 373                 cdev = devm_thermal_of_cooling_device_register(dev,
 374                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 375                 if (IS_ERR(cdev)) {
 376                         ret = PTR_ERR(cdev);
 377                         dev_err(dev,
 378                                 "Failed to register pwm-fan as cooling device: %d\n",
 379                                 ret);
 380                         return ret;
 381                 }
 382                 ctx->cdev = cdev;
 383                 thermal_cdev_update(cdev);
 384         }
 385
 386         return 0;
 387 }
 388
 389 static int pwm_fan_disable(struct device *dev)
 390 {
 391         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 392         struct pwm_args args;
 393         int ret;
 394
 395         pwm_get_args(ctx->pwm, &args);
 396
 397         if (ctx->pwm_value) {
 398                 ret = pwm_config(ctx->pwm, 0, args.period);
 399                 if (ret < 0)
 400                         return ret;
 401
 402                 pwm_disable(ctx->pwm);
 403         }
 404
 405         if (ctx->reg_en) {
 406                 ret = regulator_disable(ctx->reg_en);
 407                 if (ret) {
 408                         dev_err(dev, "Failed to disable fan supply: %d\n", ret);
 409                         return ret;
 410                 }
 411         }
 412
 413         return 0;
 414 }
 415
 416 static void pwm_fan_shutdown(struct platform_device *pdev)
 417 {
 418         pwm_fan_disable(&pdev->dev);
 419 }
 420
 421 #ifdef CONFIG_PM_SLEEP
 422 static int pwm_fan_suspend(struct device *dev)
 423 {
 424         return pwm_fan_disable(dev);
 425 }
 426
 427 static int pwm_fan_resume(struct device *dev)
 428 {
 429         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 430         struct pwm_args pargs;
 431         unsigned long duty;
 432         int ret;
 433
 434         if (ctx->reg_en) {
 435                 ret = regulator_enable(ctx->reg_en);
 436                 if (ret) {
 437                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 438                         return ret;
 439                 }
 440         }
 441
 442         if (ctx->pwm_value == 0)
 443                 return 0;
 444
 445         pwm_get_args(ctx->pwm, &pargs);
 446         duty = DIV_ROUND_UP_ULL(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
 447         ret = pwm_config(ctx->pwm, duty, pargs.period);
 448         if (ret)
 449                 return ret;
 450         return pwm_enable(ctx->pwm);
 451 }
 452 #endif
 453
 454 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 455
 456 static const struct of_device_id of_pwm_fan_match[] = {
 457         { .compatible = "pwm-fan", },
 458         {},
 459 };
 460 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 461
 462 static struct platform_driver pwm_fan_driver = {
 463         .probe          = pwm_fan_probe,
 464         .shutdown       = pwm_fan_shutdown,
 465         .driver = {
 466                 .name           = "pwm-fan",
 467                 .pm             = &pwm_fan_pm,
 468                 .of_match_table = of_pwm_fan_match,
 469         },
 470 };
 471
 472 module_platform_driver(pwm_fan_driver);
 473
 474 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 475 MODULE_ALIAS("platform:pwm-fan");
 476 MODULE_DESCRIPTION("PWM FAN driver");
 477 MODULE_LICENSE("GPL");