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         int pulses;
  58         u64 tmp;
  59
  60         pulses = atomic_read(&ctx->pulses);
  61         atomic_sub(pulses, &ctx->pulses);
  62         tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
  63         do_div(tmp, ctx->pulses_per_revolution * 1000);
  64         ctx->rpm = tmp;
  65
  66         ctx->sample_start = ktime_get();
  67         mod_timer(&ctx->rpm_timer, jiffies + HZ);
  68 }
  69
  70 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
  71 {
  72         unsigned long period;
  73         int ret = 0;
  74         struct pwm_state state = { };
  75
  76         mutex_lock(&ctx->lock);
  77         if (ctx->pwm_value == pwm)
  78                 goto exit_set_pwm_err;
  79
  80         pwm_init_state(ctx->pwm, &state);
  81         period = ctx->pwm->args.period;
  82         state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
  83         state.enabled = pwm ? true : false;
  84
  85         ret = pwm_apply_state(ctx->pwm, &state);
  86         if (!ret)
  87                 ctx->pwm_value = pwm;
  88 exit_set_pwm_err:
  89         mutex_unlock(&ctx->lock);
  90         return ret;
  91 }
  92
  93 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
  94 {
  95         int i;
  96
  97         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
  98                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
  99                         break;
 100
 101         ctx->pwm_fan_state = i;
 102 }
 103
 104 static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
 105                          const char *buf, size_t count)
 106 {
 107         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 108         unsigned long pwm;
 109         int ret;
 110
 111         if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
 112                 return -EINVAL;
 113
 114         ret = __set_pwm(ctx, pwm);
 115         if (ret)
 116                 return ret;
 117
 118         pwm_fan_update_state(ctx, pwm);
 119         return count;
 120 }
 121
 122 static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
 123                         char *buf)
 124 {
 125         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 126
 127         return sprintf(buf, "%u\n", ctx->pwm_value);
 128 }
 129
 130 static ssize_t rpm_show(struct device *dev,
 131                         struct device_attribute *attr, char *buf)
 132 {
 133         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 134
 135         return sprintf(buf, "%u\n", ctx->rpm);
 136 }
 137
 138 static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
 139 static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
 140
 141 static struct attribute *pwm_fan_attrs[] = {
 142         &sensor_dev_attr_pwm1.dev_attr.attr,
 143         &sensor_dev_attr_fan1_input.dev_attr.attr,
 144         NULL,
 145 };
 146
 147 static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
 148                                      int n)
 149 {
 150         struct device *dev = container_of(kobj, struct device, kobj);
 151         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 152
 153         /* Hide fan_input in case no interrupt is available  */
 154         if (n == 1 && ctx->irq <= 0)
 155                 return 0;
 156
 157         return a->mode;
 158 }
 159
 160 static const struct attribute_group pwm_fan_group = {
 161         .attrs = pwm_fan_attrs,
 162         .is_visible = pwm_fan_attrs_visible,
 163 };
 164
 165 static const struct attribute_group *pwm_fan_groups[] = {
 166         &pwm_fan_group,
 167         NULL,
 168 };
 169
 170 /* thermal cooling device callbacks */
 171 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 172                                  unsigned long *state)
 173 {
 174         struct pwm_fan_ctx *ctx = cdev->devdata;
 175
 176         if (!ctx)
 177                 return -EINVAL;
 178
 179         *state = ctx->pwm_fan_max_state;
 180
 181         return 0;
 182 }
 183
 184 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 185                                  unsigned long *state)
 186 {
 187         struct pwm_fan_ctx *ctx = cdev->devdata;
 188
 189         if (!ctx)
 190                 return -EINVAL;
 191
 192         *state = ctx->pwm_fan_state;
 193
 194         return 0;
 195 }
 196
 197 static int
 198 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 199 {
 200         struct pwm_fan_ctx *ctx = cdev->devdata;
 201         int ret;
 202
 203         if (!ctx || (state > ctx->pwm_fan_max_state))
 204                 return -EINVAL;
 205
 206         if (state == ctx->pwm_fan_state)
 207                 return 0;
 208
 209         ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 210         if (ret) {
 211                 dev_err(&cdev->device, "Cannot set pwm!\n");
 212                 return ret;
 213         }
 214
 215         ctx->pwm_fan_state = state;
 216
 217         return ret;
 218 }
 219
 220 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 221         .get_max_state = pwm_fan_get_max_state,
 222         .get_cur_state = pwm_fan_get_cur_state,
 223         .set_cur_state = pwm_fan_set_cur_state,
 224 };
 225
 226 static int pwm_fan_of_get_cooling_data(struct device *dev,
 227                                        struct pwm_fan_ctx *ctx)
 228 {
 229         struct device_node *np = dev->of_node;
 230         int num, i, ret;
 231
 232         if (!of_find_property(np, "cooling-levels", NULL))
 233                 return 0;
 234
 235         ret = of_property_count_u32_elems(np, "cooling-levels");
 236         if (ret <= 0) {
 237                 dev_err(dev, "Wrong data!\n");
 238                 return ret ? : -EINVAL;
 239         }
 240
 241         num = ret;
 242         ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
 243                                                    GFP_KERNEL);
 244         if (!ctx->pwm_fan_cooling_levels)
 245                 return -ENOMEM;
 246
 247         ret = of_property_read_u32_array(np, "cooling-levels",
 248                                          ctx->pwm_fan_cooling_levels, num);
 249         if (ret) {
 250                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 251                 return ret;
 252         }
 253
 254         for (i = 0; i < num; i++) {
 255                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 256                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 257                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 258                         return -EINVAL;
 259                 }
 260         }
 261
 262         ctx->pwm_fan_max_state = num - 1;
 263
 264         return 0;
 265 }
 266
 267 static void pwm_fan_regulator_disable(void *data)
 268 {
 269         regulator_disable(data);
 270 }
 271
 272 static void pwm_fan_pwm_disable(void *__ctx)
 273 {
 274         struct pwm_fan_ctx *ctx = __ctx;
 275         pwm_disable(ctx->pwm);
 276         del_timer_sync(&ctx->rpm_timer);
 277 }
 278
 279 static int pwm_fan_probe(struct platform_device *pdev)
 280 {
 281         struct thermal_cooling_device *cdev;
 282         struct device *dev = &pdev->dev;
 283         struct pwm_fan_ctx *ctx;
 284         struct device *hwmon;
 285         int ret;
 286         struct pwm_state state = { };
 287         u32 ppr = 2;
 288
 289         ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 290         if (!ctx)
 291                 return -ENOMEM;
 292
 293         mutex_init(&ctx->lock);
 294
 295         ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
 296         if (IS_ERR(ctx->pwm)) {
 297                 ret = PTR_ERR(ctx->pwm);
 298
 299                 if (ret != -EPROBE_DEFER)
 300                         dev_err(dev, "Could not get PWM: %d\n", ret);
 301
 302                 return ret;
 303         }
 304
 305         platform_set_drvdata(pdev, ctx);
 306
 307         ctx->irq = platform_get_irq_optional(pdev, 0);
 308         if (ctx->irq == -EPROBE_DEFER)
 309                 return ctx->irq;
 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         ctx->pwm_value = MAX_PWM;
 330
 331         /* Set duty cycle to maximum allowed and enable PWM output */
 332         pwm_init_state(ctx->pwm, &state);
 333         state.duty_cycle = ctx->pwm->args.period - 1;
 334         state.enabled = true;
 335
 336         ret = pwm_apply_state(ctx->pwm, &state);
 337         if (ret) {
 338                 dev_err(dev, "Failed to configure PWM: %d\n", ret);
 339                 return ret;
 340         }
 341         timer_setup(&ctx->rpm_timer, sample_timer, 0);
 342         ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
 343         if (ret)
 344                 return ret;
 345
 346         of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);
 347         ctx->pulses_per_revolution = ppr;
 348         if (!ctx->pulses_per_revolution) {
 349                 dev_err(dev, "pulses-per-revolution can't be zero.\n");
 350                 return -EINVAL;
 351         }
 352
 353         if (ctx->irq > 0) {
 354                 ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
 355                                        pdev->name, ctx);
 356                 if (ret) {
 357                         dev_err(dev, "Failed to request interrupt: %d\n", ret);
 358                         return ret;
 359                 }
 360                 ctx->sample_start = ktime_get();
 361                 mod_timer(&ctx->rpm_timer, jiffies + HZ);
 362         }
 363
 364         hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
 365                                                        ctx, pwm_fan_groups);
 366         if (IS_ERR(hwmon)) {
 367                 dev_err(dev, "Failed to register hwmon device\n");
 368                 return PTR_ERR(hwmon);
 369         }
 370
 371         ret = pwm_fan_of_get_cooling_data(dev, ctx);
 372         if (ret)
 373                 return ret;
 374
 375         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 376         if (IS_ENABLED(CONFIG_THERMAL)) {
 377                 cdev = devm_thermal_of_cooling_device_register(dev,
 378                         dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 379                 if (IS_ERR(cdev)) {
 380                         ret = PTR_ERR(cdev);
 381                         dev_err(dev,
 382                                 "Failed to register pwm-fan as cooling device: %d\n",
 383                                 ret);
 384                         return ret;
 385                 }
 386                 ctx->cdev = cdev;
 387                 thermal_cdev_update(cdev);
 388         }
 389
 390         return 0;
 391 }
 392
 393 #ifdef CONFIG_PM_SLEEP
 394 static int pwm_fan_suspend(struct device *dev)
 395 {
 396         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 397         struct pwm_args args;
 398         int ret;
 399
 400         pwm_get_args(ctx->pwm, &args);
 401
 402         if (ctx->pwm_value) {
 403                 ret = pwm_config(ctx->pwm, 0, args.period);
 404                 if (ret < 0)
 405                         return ret;
 406
 407                 pwm_disable(ctx->pwm);
 408         }
 409
 410         if (ctx->reg_en) {
 411                 ret = regulator_disable(ctx->reg_en);
 412                 if (ret) {
 413                         dev_err(dev, "Failed to disable fan supply: %d\n", ret);
 414                         return ret;
 415                 }
 416         }
 417
 418         return 0;
 419 }
 420
 421 static int pwm_fan_resume(struct device *dev)
 422 {
 423         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 424         struct pwm_args pargs;
 425         unsigned long duty;
 426         int ret;
 427
 428         if (ctx->reg_en) {
 429                 ret = regulator_enable(ctx->reg_en);
 430                 if (ret) {
 431                         dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 432                         return ret;
 433                 }
 434         }
 435
 436         if (ctx->pwm_value == 0)
 437                 return 0;
 438
 439         pwm_get_args(ctx->pwm, &pargs);
 440         duty = DIV_ROUND_UP(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
 441         ret = pwm_config(ctx->pwm, duty, pargs.period);
 442         if (ret)
 443                 return ret;
 444         return pwm_enable(ctx->pwm);
 445 }
 446 #endif
 447
 448 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 449
 450 static const struct of_device_id of_pwm_fan_match[] = {
 451         { .compatible = "pwm-fan", },
 452         {},
 453 };
 454 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 455
 456 static struct platform_driver pwm_fan_driver = {
 457         .probe          = pwm_fan_probe,
 458         .driver = {
 459                 .name           = "pwm-fan",
 460                 .pm             = &pwm_fan_pm,
 461                 .of_match_table = of_pwm_fan_match,
 462         },
 463 };
 464
 465 module_platform_driver(pwm_fan_driver);
 466
 467 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 468 MODULE_ALIAS("platform:pwm-fan");
 469 MODULE_DESCRIPTION("PWM FAN driver");
 470 MODULE_LICENSE("GPL");