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/module.h>
  22 #include <linux/mutex.h>
  23 #include <linux/of.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/pwm.h>
  26 #include <linux/sysfs.h>
  27 #include <linux/thermal.h>
  28
  29 #define MAX_PWM 255
  30
  31 struct pwm_fan_ctx {
  32         struct mutex lock;
  33         struct pwm_device *pwm;
  34         unsigned int pwm_value;
  35         unsigned int pwm_fan_state;
  36         unsigned int pwm_fan_max_state;
  37         unsigned int *pwm_fan_cooling_levels;
  38         struct thermal_cooling_device *cdev;
  39 };
  40
  41 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
  42 {
  43         unsigned long duty;
  44         int ret = 0;
  45
  46         mutex_lock(&ctx->lock);
  47         if (ctx->pwm_value == pwm)
  48                 goto exit_set_pwm_err;
  49
  50         duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM);
  51         ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
  52         if (ret)
  53                 goto exit_set_pwm_err;
  54
  55         if (pwm == 0)
  56                 pwm_disable(ctx->pwm);
  57
  58         if (ctx->pwm_value == 0) {
  59                 ret = pwm_enable(ctx->pwm);
  60                 if (ret)
  61                         goto exit_set_pwm_err;
  62         }
  63
  64         ctx->pwm_value = pwm;
  65 exit_set_pwm_err:
  66         mutex_unlock(&ctx->lock);
  67         return ret;
  68 }
  69
  70 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
  71 {
  72         int i;
  73
  74         for (i = 0; i < ctx->pwm_fan_max_state; ++i)
  75                 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
  76                         break;
  77
  78         ctx->pwm_fan_state = i;
  79 }
  80
  81 static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
  82                        const char *buf, size_t count)
  83 {
  84         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
  85         unsigned long pwm;
  86         int ret;
  87
  88         if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
  89                 return -EINVAL;
  90
  91         ret = __set_pwm(ctx, pwm);
  92         if (ret)
  93                 return ret;
  94
  95         pwm_fan_update_state(ctx, pwm);
  96         return count;
  97 }
  98
  99 static ssize_t show_pwm(struct device *dev,
 100                         struct device_attribute *attr, char *buf)
 101 {
 102         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 103
 104         return sprintf(buf, "%u\n", ctx->pwm_value);
 105 }
 106
 107
 108 static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
 109
 110 static struct attribute *pwm_fan_attrs[] = {
 111         &sensor_dev_attr_pwm1.dev_attr.attr,
 112         NULL,
 113 };
 114
 115 ATTRIBUTE_GROUPS(pwm_fan);
 116
 117 /* thermal cooling device callbacks */
 118 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
 119                                  unsigned long *state)
 120 {
 121         struct pwm_fan_ctx *ctx = cdev->devdata;
 122
 123         if (!ctx)
 124                 return -EINVAL;
 125
 126         *state = ctx->pwm_fan_max_state;
 127
 128         return 0;
 129 }
 130
 131 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
 132                                  unsigned long *state)
 133 {
 134         struct pwm_fan_ctx *ctx = cdev->devdata;
 135
 136         if (!ctx)
 137                 return -EINVAL;
 138
 139         *state = ctx->pwm_fan_state;
 140
 141         return 0;
 142 }
 143
 144 static int
 145 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
 146 {
 147         struct pwm_fan_ctx *ctx = cdev->devdata;
 148         int ret;
 149
 150         if (!ctx || (state > ctx->pwm_fan_max_state))
 151                 return -EINVAL;
 152
 153         if (state == ctx->pwm_fan_state)
 154                 return 0;
 155
 156         ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
 157         if (ret) {
 158                 dev_err(&cdev->device, "Cannot set pwm!\n");
 159                 return ret;
 160         }
 161
 162         ctx->pwm_fan_state = state;
 163
 164         return ret;
 165 }
 166
 167 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 168         .get_max_state = pwm_fan_get_max_state,
 169         .get_cur_state = pwm_fan_get_cur_state,
 170         .set_cur_state = pwm_fan_set_cur_state,
 171 };
 172
 173 static int pwm_fan_of_get_cooling_data(struct device *dev,
 174                                        struct pwm_fan_ctx *ctx)
 175 {
 176         struct device_node *np = dev->of_node;
 177         int num, i, ret;
 178
 179         if (!of_find_property(np, "cooling-levels", NULL))
 180                 return 0;
 181
 182         ret = of_property_count_u32_elems(np, "cooling-levels");
 183         if (ret <= 0) {
 184                 dev_err(dev, "Wrong data!\n");
 185                 return ret ? : -EINVAL;
 186         }
 187
 188         num = ret;
 189         ctx->pwm_fan_cooling_levels = devm_kzalloc(dev, num * sizeof(u32),
 190                                                    GFP_KERNEL);
 191         if (!ctx->pwm_fan_cooling_levels)
 192                 return -ENOMEM;
 193
 194         ret = of_property_read_u32_array(np, "cooling-levels",
 195                                          ctx->pwm_fan_cooling_levels, num);
 196         if (ret) {
 197                 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
 198                 return ret;
 199         }
 200
 201         for (i = 0; i < num; i++) {
 202                 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
 203                         dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
 204                                 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
 205                         return -EINVAL;
 206                 }
 207         }
 208
 209         ctx->pwm_fan_max_state = num - 1;
 210
 211         return 0;
 212 }
 213
 214 static int pwm_fan_probe(struct platform_device *pdev)
 215 {
 216         struct thermal_cooling_device *cdev;
 217         struct pwm_fan_ctx *ctx;
 218         struct device *hwmon;
 219         int duty_cycle;
 220         int ret;
 221
 222         ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
 223         if (!ctx)
 224                 return -ENOMEM;
 225
 226         mutex_init(&ctx->lock);
 227
 228         ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
 229         if (IS_ERR(ctx->pwm)) {
 230                 dev_err(&pdev->dev, "Could not get PWM\n");
 231                 return PTR_ERR(ctx->pwm);
 232         }
 233
 234         platform_set_drvdata(pdev, ctx);
 235
 236         /* Set duty cycle to maximum allowed */
 237         duty_cycle = ctx->pwm->period - 1;
 238         ctx->pwm_value = MAX_PWM;
 239
 240         ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
 241         if (ret) {
 242                 dev_err(&pdev->dev, "Failed to configure PWM\n");
 243                 return ret;
 244         }
 245
 246         /* Enbale PWM output */
 247         ret = pwm_enable(ctx->pwm);
 248         if (ret) {
 249                 dev_err(&pdev->dev, "Failed to enable PWM\n");
 250                 return ret;
 251         }
 252
 253         hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
 254                                                        ctx, pwm_fan_groups);
 255         if (IS_ERR(hwmon)) {
 256                 dev_err(&pdev->dev, "Failed to register hwmon device\n");
 257                 pwm_disable(ctx->pwm);
 258                 return PTR_ERR(hwmon);
 259         }
 260
 261         ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
 262         if (ret)
 263                 return ret;
 264
 265         ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 266         if (IS_ENABLED(CONFIG_THERMAL)) {
 267                 cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
 268                                                           "pwm-fan", ctx,
 269                                                           &pwm_fan_cooling_ops);
 270                 if (IS_ERR(cdev)) {
 271                         dev_err(&pdev->dev,
 272                                 "Failed to register pwm-fan as cooling device");
 273                         pwm_disable(ctx->pwm);
 274                         return PTR_ERR(cdev);
 275                 }
 276                 ctx->cdev = cdev;
 277                 thermal_cdev_update(cdev);
 278         }
 279
 280         return 0;
 281 }
 282
 283 static int pwm_fan_remove(struct platform_device *pdev)
 284 {
 285         struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
 286
 287         thermal_cooling_device_unregister(ctx->cdev);
 288         if (ctx->pwm_value)
 289                 pwm_disable(ctx->pwm);
 290         return 0;
 291 }
 292
 293 #ifdef CONFIG_PM_SLEEP
 294 static int pwm_fan_suspend(struct device *dev)
 295 {
 296         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 297
 298         if (ctx->pwm_value)
 299                 pwm_disable(ctx->pwm);
 300         return 0;
 301 }
 302
 303 static int pwm_fan_resume(struct device *dev)
 304 {
 305         struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 306         unsigned long duty;
 307         int ret;
 308
 309         if (ctx->pwm_value == 0)
 310                 return 0;
 311
 312         duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM);
 313         ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
 314         if (ret)
 315                 return ret;
 316         return pwm_enable(ctx->pwm);
 317 }
 318 #endif
 319
 320 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
 321
 322 static const struct of_device_id of_pwm_fan_match[] = {
 323         { .compatible = "pwm-fan", },
 324         {},
 325 };
 326
 327 static struct platform_driver pwm_fan_driver = {
 328         .probe          = pwm_fan_probe,
 329         .remove         = pwm_fan_remove,
 330         .driver = {
 331                 .name           = "pwm-fan",
 332                 .pm             = &pwm_fan_pm,
 333                 .of_match_table = of_pwm_fan_match,
 334         },
 335 };
 336
 337 module_platform_driver(pwm_fan_driver);
 338
 339 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
 340 MODULE_ALIAS("platform:pwm-fan");
 341 MODULE_DESCRIPTION("PWM FAN driver");
 342 MODULE_LICENSE("GPL");