drivers/hwmon/pwm-fan.c

   1 /*
   2  * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
   3  *
   4  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   5  *
   6  * Author: Kamil Debski <k.debski@samsung.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  */
  18
  19 #include <linux/hwmon.h>
  20 #include <linux/hwmon-sysfs.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/module.h>
  23 #include <linux/mutex.h>
  24 #include <linux/of.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/pwm.h>
  27 #include <linux/regulator/consumer.h>
  28 #include <linux/sysfs.h>
  29 #include <linux/thermal.h>
  30 #include <linux/timer.h>
  31
  32 #define MAX_PWM 255
  33
  34 struct pwm_fan_ctx {
  35         struct mutex lock;
  36         struct pwm_device *pwm;
  37         struct regulator *reg_en;
  38
  39         int irq;
  40         atomic_t pulses;
  41         unsigned int rpm;
  42         u8 pulses_per_revolution;
  43         ktime_t sample_start;
  44         struct timer_list rpm_timer;
  45
  46         unsigned int pwm_value;
  47         unsigned int pwm_fan_state;
  48         unsigned int pwm_fan_max_state;
  49         unsigned int *pwm_fan_cooling_levels;
  50         struct thermal_cooling_device *cdev;
  51 };
  52
  53 /* This handler assumes self resetting edge triggered interrupt. */
  54 static irqreturn_t pulse_handler(int irq, void *dev_id)
  55 {
  56         struct pwm_fan_ctx *ctx = dev_id;
  57
  58         atomic_inc(&ctx->pulses);
  59
  60         return IRQ_HANDLED;
  61 }
  62
  63 static void sample_timer(struct timer_list *t)
  64 {
  65         struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
  66         int pulses;
  67         u64 tmp;
  68
  69         pulses = atomic_read(&ctx->pulses);
  70         atomic_sub(pulses, &ctx->pulses);
  71         tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
  72         do_div(tmp, ctx->pulses_per_revolution * 1000);
  73         ctx->rpm = tmp;
  74
  75         ctx->sample_start = ktime_get();
  76         mod_timer(&ctx->rpm_timer, jiffies + HZ);
  77 }
  78
  79 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
  80 {
  81         unsigned long period;
  82         int ret = 0;
  83         struct pwm_state state = { };
  84
  85         mutex_lock(&ctx->lock);
  86         if (ctx->pwm_value == pwm)
  87                 goto exit_set_pwm_err;
  88
  89         pwm_init_state(ctx->pwm, &state);
  90         period = ctx->pwm->args.period;
  91         state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
  92         state.enabled = pwm ? true : false;
  93
  94         ret = pwm_apply_state(ctx->pwm, &state);
  95         if (!ret)
  96                 ctx->pwm_value = pwm;
  97 exit_set_pwm_err:
  98         mutex_unlock(&ctx->lock);
  99         return ret;
 100 }
 101
 102 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
 103 {
 104         int i;
 105
 106         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
 107                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
 108                         break;
 109
 110         ctx->pwm_fan_state = i;
 111 }
 112
 113 static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
 114                          const char *buf, size_t count)
 115 {
 116         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 117         unsigned long pwm;
 118         int ret;
 119
 120         if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
 121                 return -EINVAL;
 122
 123         ret = __set_pwm(ctx, pwm);
 124         if (ret)
 125                 return ret;
 126
 127         pwm_fan_update_state(ctx, pwm);
 128         return count;
 129 }
 130
 131 static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
 132                         char *buf)
 133 {
 134         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 135
 136         return sprintf(buf, "%u\n", ctx->pwm_value);
 137 }
 138
 139 static ssize_t rpm_show(struct device *dev,
 140                         struct device_attribute *attr, char *buf)
 141 {
 142         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 143
 144         return sprintf(buf, "%u\n", ctx->rpm);
 145 }
 146
 147 static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
 148 static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
 149
 150 static struct attribute *pwm_fan_attrs[] = {
 151         &sensor_dev_attr_pwm1.dev_attr.attr,
 152         &sensor_dev_attr_fan1_input.dev_attr.attr,
 153         NULL,
 154 };
 155
 156 static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
 157                                      int n)
 158 {
 159         struct device *dev = container_of(kobj, struct device, kobj);
 160         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 161
 162         /* Hide fan_input in case no interrupt is available  */
 163         if (n == 1 && ctx->irq <= 0)
 164                 return 0;
 165
 166         return a->mode;
 167 }
 168
 169 static const struct attribute_group pwm_fan_group = {
 170         .attrs = pwm_fan_attrs,
 171         .is_visible = pwm_fan_attrs_visible,
 172 };
 173
 174 static const struct attribute_group *pwm_fan_groups[] = {
 175         &pwm_fan_group,
 176         NULL,
 177 };
 178
 179 /* thermal cooling device callbacks */
 180 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 181                                  unsigned long *state)
 182 {
 183         struct pwm_fan_ctx *ctx = cdev->devdata;
 184
 185         if (!ctx)
 186                 return -EINVAL;
 187
 188         *state = ctx->pwm_fan_max_state;
 189
 190         return 0;
 191 }
 192
 193 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 194                                  unsigned long *state)
 195 {
 196         struct pwm_fan_ctx *ctx = cdev->devdata;
 197
 198         if (!ctx)
 199                 return -EINVAL;
 200
 201         *state = ctx->pwm_fan_state;
 202
 203         return 0;
 204 }
 205
 206 static int
 207 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 208 {
 209         struct pwm_fan_ctx *ctx = cdev->devdata;
 210         int ret;
 211
 212         if (!ctx || (state > ctx->pwm_fan_max_state))
 213                 return -EINVAL;
 214
 215         if (state == ctx->pwm_fan_state)
 216                 return 0;
 217
 218         ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 219         if (ret) {
 220                 dev_err(&cdev->device, "Cannot set pwm!\n");
 221                 return ret;
 222         }
 223
 224         ctx->pwm_fan_state = state;
 225
 226         return ret;
 227 }
 228
 229 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 230         .get_max_state = pwm_fan_get_max_state,
 231         .get_cur_state = pwm_fan_get_cur_state,
 232         .set_cur_state = pwm_fan_set_cur_state,
 233 };
 234
 235 static int pwm_fan_of_get_cooling_data(struct device *dev,
 236                                        struct pwm_fan_ctx *ctx)
 237 {
 238         struct device_node *np = dev->of_node;
 239         int num, i, ret;
 240
 241         if (!of_find_property(np, "cooling-levels", NULL))
 242                 return 0;
 243
 244         ret = of_property_count_u32_elems(np, "cooling-levels");
 245         if (ret <= 0) {
 246                 dev_err(dev, "Wrong data!\n");
 247                 return ret ? : -EINVAL;
 248         }
 249
 250         num = ret;
 251         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 252                                                    GFP_KERNEL);
 253         if (!ctx->pwm_fan_cooling_levels)
 254                 return -ENOMEM;
 255
 256         ret = of_property_read_u32_array(np, "cooling-levels",
 257                                          ctx->pwm_fan_cooling_levels, num);
 258         if (ret) {
 259                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 260                 return ret;
 261         }
 262
 263         for (i = 0; i < num; i++) {
 264                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 265                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 266                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 267                         return -EINVAL;
 268                 }
 269         }
 270
 271         ctx->pwm_fan_max_state = num - 1;
 272
 273         return 0;
 274 }
 275
 276 static void pwm_fan_regulator_disable(void *data)
 277 {
 278         regulator_disable(data);
 279 }
 280
 281 static void pwm_fan_pwm_disable(void *__ctx)
 282 {
 283         struct pwm_fan_ctx *ctx = __ctx;
 284         pwm_disable(ctx->pwm);
 285         del_timer_sync(&ctx->rpm_timer);
 286 }
 287
 288 static int pwm_fan_probe(struct platform_device *pdev)
 289 {
 290         struct thermal_cooling_device *cdev;
 291         struct device *dev = &pdev->dev;
 292         struct pwm_fan_ctx *ctx;
 293         struct device *hwmon;
 294         int ret;
 295         struct pwm_state state = { };
 296         u32 ppr = 2;
 297
 298         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 299         if (!ctx)
 300                 return -ENOMEM;
 301
 302         mutex_init(&ctx->lock);
 303
 304         ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
 305         if (IS_ERR(ctx->pwm)) {
 306                 ret = PTR_ERR(ctx->pwm);
 307
 308                 if (ret != -EPROBE_DEFER)
 309                         dev_err(dev, "Could not get PWM: %d\n", ret);
 310
 311                 return ret;
 312         }
 313
 314         platform_set_drvdata(pdev, ctx);
 315
 316         ctx->irq = platform_get_irq(pdev, 0);
 317         if (ctx->irq == -EPROBE_DEFER)
 318                 return ctx->irq;
 319
 320         ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 321         if (IS_ERR(ctx->reg_en)) {
 322                 if (PTR_ERR(ctx->reg_en) != -ENODEV)
 323                         return PTR_ERR(ctx->reg_en);
 324
 325                 ctx->reg_en = NULL;
 326         } else {
 327                 ret = regulator_enable(ctx->reg_en);
 328                 if (ret) {
 329                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 330                         return ret;
 331                 }
 332                 devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
 333                                          ctx->reg_en);
 334         }
 335
 336         ctx->pwm_value = MAX_PWM;
 337
 338         /* Set duty cycle to maximum allowed and enable PWM output */
 339         pwm_init_state(ctx->pwm, &state);
 340         state.duty_cycle = ctx->pwm->args.period - 1;
 341         state.enabled = true;
 342
 343         ret = pwm_apply_state(ctx->pwm, &state);
 344         if (ret) {
 345                 dev_err(dev, "Failed to configure PWM: %d\n", ret);
 346                 return ret;
 347         }
 348         timer_setup(&ctx->rpm_timer, sample_timer, 0);
 349         devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
 350
 351         of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);
 352         ctx->pulses_per_revolution = ppr;
 353         if (!ctx->pulses_per_revolution) {
 354                 dev_err(dev, "pulses-per-revolution can't be zero.\n");
 355                 return -EINVAL;
 356         }
 357
 358         if (ctx->irq > 0) {
 359                 ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
 360                                        pdev->name, ctx);
 361                 if (ret) {
 362                         dev_err(dev, "Failed to request interrupt: %d\n", ret);
 363                         return ret;
 364                 }
 365                 ctx->sample_start = ktime_get();
 366                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 367         }
 368
 369         hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
 370                                                        ctx, pwm_fan_groups);
 371         if (IS_ERR(hwmon)) {
 372                 dev_err(dev, "Failed to register hwmon device\n");
 373                 return PTR_ERR(hwmon);
 374         }
 375
 376         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 377         if (ret)
 378                 return ret;
 379
 380         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 381         if (IS_ENABLED(CONFIG_THERMAL)) {
 382                 cdev = devm_thermal_of_cooling_device_register(dev,
 383                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 384                 if (IS_ERR(cdev)) {
 385                         ret = PTR_ERR(cdev);
 386                         dev_err(dev,
 387                                 "Failed to register pwm-fan as cooling device: %d\n",
 388                                 ret);
 389                         return ret;
 390                 }
 391                 ctx->cdev = cdev;
 392                 thermal_cdev_update(cdev);
 393         }
 394
 395         return 0;
 396 }
 397
 398 #ifdef CONFIG_PM_SLEEP
 399 static int pwm_fan_suspend(struct device *dev)
 400 {
 401         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 402         struct pwm_args args;
 403         int ret;
 404
 405         pwm_get_args(ctx->pwm, &args);
 406
 407         if (ctx->pwm_value) {
 408                 ret = pwm_config(ctx->pwm, 0, args.period);
 409                 if (ret < 0)
 410                         return ret;
 411
 412                 pwm_disable(ctx->pwm);
 413         }
 414
 415         if (ctx->reg_en) {
 416                 ret = regulator_disable(ctx->reg_en);
 417                 if (ret) {
 418                         dev_err(dev, "Failed to disable fan supply: %d\n", ret);
 419                         return ret;
 420                 }
 421         }
 422
 423         return 0;
 424 }
 425
 426 static int pwm_fan_resume(struct device *dev)
 427 {
 428         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 429         struct pwm_args pargs;
 430         unsigned long duty;
 431         int ret;
 432
 433         if (ctx->reg_en) {
 434                 ret = regulator_enable(ctx->reg_en);
 435                 if (ret) {
 436                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 437                         return ret;
 438                 }
 439         }
 440
 441         if (ctx->pwm_value == 0)
 442                 return 0;
 443
 444         pwm_get_args(ctx->pwm, &pargs);
 445         duty = DIV_ROUND_UP(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
 446         ret = pwm_config(ctx->pwm, duty, pargs.period);
 447         if (ret)
 448                 return ret;
 449         return pwm_enable(ctx->pwm);
 450 }
 451 #endif
 452
 453 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 454
 455 static const struct of_device_id of_pwm_fan_match[] = {
 456         { .compatible = "pwm-fan", },
 457         {},
 458 };
 459 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 460
 461 static struct platform_driver pwm_fan_driver = {
 462         .probe          = pwm_fan_probe,
 463         .driver = {
 464                 .name           = "pwm-fan",
 465                 .pm             = &pwm_fan_pm,
 466                 .of_match_table = of_pwm_fan_match,
 467         },
 468 };
 469
 470 module_platform_driver(pwm_fan_driver);
 471
 472 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 473 MODULE_ALIAS("platform:pwm-fan");
 474 MODULE_DESCRIPTION("PWM FAN driver");
 475 MODULE_LICENSE("GPL");