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