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