linux/drivers/hwmon/gpio-fan.c
<<
>>
Prefs
   1/*
   2 * gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
   3 *
   4 * Copyright (C) 2010 LaCie
   5 *
   6 * Author: Simon Guinot <sguinot@lacie.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 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 */
  22
  23#include <linux/module.h>
  24#include <linux/init.h>
  25#include <linux/slab.h>
  26#include <linux/interrupt.h>
  27#include <linux/irq.h>
  28#include <linux/platform_device.h>
  29#include <linux/err.h>
  30#include <linux/mutex.h>
  31#include <linux/hwmon.h>
  32#include <linux/gpio.h>
  33#include <linux/gpio-fan.h>
  34#include <linux/of.h>
  35#include <linux/of_platform.h>
  36#include <linux/of_gpio.h>
  37#include <linux/thermal.h>
  38
  39struct gpio_fan_data {
  40        struct platform_device  *pdev;
  41        struct device           *hwmon_dev;
  42        /* Cooling device if any */
  43        struct thermal_cooling_device *cdev;
  44        struct mutex            lock; /* lock GPIOs operations. */
  45        int                     num_ctrl;
  46        unsigned                *ctrl;
  47        int                     num_speed;
  48        struct gpio_fan_speed   *speed;
  49        int                     speed_index;
  50#ifdef CONFIG_PM_SLEEP
  51        int                     resume_speed;
  52#endif
  53        bool                    pwm_enable;
  54        struct gpio_fan_alarm   *alarm;
  55        struct work_struct      alarm_work;
  56};
  57
  58/*
  59 * Alarm GPIO.
  60 */
  61
  62static void fan_alarm_notify(struct work_struct *ws)
  63{
  64        struct gpio_fan_data *fan_data =
  65                container_of(ws, struct gpio_fan_data, alarm_work);
  66
  67        sysfs_notify(&fan_data->pdev->dev.kobj, NULL, "fan1_alarm");
  68        kobject_uevent(&fan_data->pdev->dev.kobj, KOBJ_CHANGE);
  69}
  70
  71static irqreturn_t fan_alarm_irq_handler(int irq, void *dev_id)
  72{
  73        struct gpio_fan_data *fan_data = dev_id;
  74
  75        schedule_work(&fan_data->alarm_work);
  76
  77        return IRQ_NONE;
  78}
  79
  80static ssize_t show_fan_alarm(struct device *dev,
  81                              struct device_attribute *attr, char *buf)
  82{
  83        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
  84        struct gpio_fan_alarm *alarm = fan_data->alarm;
  85        int value = gpio_get_value_cansleep(alarm->gpio);
  86
  87        if (alarm->active_low)
  88                value = !value;
  89
  90        return sprintf(buf, "%d\n", value);
  91}
  92
  93static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
  94
  95static int fan_alarm_init(struct gpio_fan_data *fan_data,
  96                          struct gpio_fan_alarm *alarm)
  97{
  98        int err;
  99        int alarm_irq;
 100        struct platform_device *pdev = fan_data->pdev;
 101
 102        fan_data->alarm = alarm;
 103
 104        err = devm_gpio_request(&pdev->dev, alarm->gpio, "GPIO fan alarm");
 105        if (err)
 106                return err;
 107
 108        err = gpio_direction_input(alarm->gpio);
 109        if (err)
 110                return err;
 111
 112        /*
 113         * If the alarm GPIO don't support interrupts, just leave
 114         * without initializing the fail notification support.
 115         */
 116        alarm_irq = gpio_to_irq(alarm->gpio);
 117        if (alarm_irq < 0)
 118                return 0;
 119
 120        INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
 121        irq_set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
 122        err = devm_request_irq(&pdev->dev, alarm_irq, fan_alarm_irq_handler,
 123                               IRQF_SHARED, "GPIO fan alarm", fan_data);
 124        return err;
 125}
 126
 127/*
 128 * Control GPIOs.
 129 */
 130
 131/* Must be called with fan_data->lock held, except during initialization. */
 132static void __set_fan_ctrl(struct gpio_fan_data *fan_data, int ctrl_val)
 133{
 134        int i;
 135
 136        for (i = 0; i < fan_data->num_ctrl; i++)
 137                gpio_set_value_cansleep(fan_data->ctrl[i], (ctrl_val >> i) & 1);
 138}
 139
 140static int __get_fan_ctrl(struct gpio_fan_data *fan_data)
 141{
 142        int i;
 143        int ctrl_val = 0;
 144
 145        for (i = 0; i < fan_data->num_ctrl; i++) {
 146                int value;
 147
 148                value = gpio_get_value_cansleep(fan_data->ctrl[i]);
 149                ctrl_val |= (value << i);
 150        }
 151        return ctrl_val;
 152}
 153
 154/* Must be called with fan_data->lock held, except during initialization. */
 155static void set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
 156{
 157        if (fan_data->speed_index == speed_index)
 158                return;
 159
 160        __set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
 161        fan_data->speed_index = speed_index;
 162}
 163
 164static int get_fan_speed_index(struct gpio_fan_data *fan_data)
 165{
 166        int ctrl_val = __get_fan_ctrl(fan_data);
 167        int i;
 168
 169        for (i = 0; i < fan_data->num_speed; i++)
 170                if (fan_data->speed[i].ctrl_val == ctrl_val)
 171                        return i;
 172
 173        dev_warn(&fan_data->pdev->dev,
 174                 "missing speed array entry for GPIO value 0x%x\n", ctrl_val);
 175
 176        return -ENODEV;
 177}
 178
 179static int rpm_to_speed_index(struct gpio_fan_data *fan_data, unsigned long rpm)
 180{
 181        struct gpio_fan_speed *speed = fan_data->speed;
 182        int i;
 183
 184        for (i = 0; i < fan_data->num_speed; i++)
 185                if (speed[i].rpm >= rpm)
 186                        return i;
 187
 188        return fan_data->num_speed - 1;
 189}
 190
 191static ssize_t show_pwm(struct device *dev,
 192                        struct device_attribute *attr, char *buf)
 193{
 194        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 195        u8 pwm = fan_data->speed_index * 255 / (fan_data->num_speed - 1);
 196
 197        return sprintf(buf, "%d\n", pwm);
 198}
 199
 200static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
 201                       const char *buf, size_t count)
 202{
 203        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 204        unsigned long pwm;
 205        int speed_index;
 206        int ret = count;
 207
 208        if (kstrtoul(buf, 10, &pwm) || pwm > 255)
 209                return -EINVAL;
 210
 211        mutex_lock(&fan_data->lock);
 212
 213        if (!fan_data->pwm_enable) {
 214                ret = -EPERM;
 215                goto exit_unlock;
 216        }
 217
 218        speed_index = DIV_ROUND_UP(pwm * (fan_data->num_speed - 1), 255);
 219        set_fan_speed(fan_data, speed_index);
 220
 221exit_unlock:
 222        mutex_unlock(&fan_data->lock);
 223
 224        return ret;
 225}
 226
 227static ssize_t show_pwm_enable(struct device *dev,
 228                               struct device_attribute *attr, char *buf)
 229{
 230        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 231
 232        return sprintf(buf, "%d\n", fan_data->pwm_enable);
 233}
 234
 235static ssize_t set_pwm_enable(struct device *dev, struct device_attribute *attr,
 236                              const char *buf, size_t count)
 237{
 238        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 239        unsigned long val;
 240
 241        if (kstrtoul(buf, 10, &val) || val > 1)
 242                return -EINVAL;
 243
 244        if (fan_data->pwm_enable == val)
 245                return count;
 246
 247        mutex_lock(&fan_data->lock);
 248
 249        fan_data->pwm_enable = val;
 250
 251        /* Disable manual control mode: set fan at full speed. */
 252        if (val == 0)
 253                set_fan_speed(fan_data, fan_data->num_speed - 1);
 254
 255        mutex_unlock(&fan_data->lock);
 256
 257        return count;
 258}
 259
 260static ssize_t show_pwm_mode(struct device *dev,
 261                             struct device_attribute *attr, char *buf)
 262{
 263        return sprintf(buf, "0\n");
 264}
 265
 266static ssize_t show_rpm_min(struct device *dev,
 267                            struct device_attribute *attr, char *buf)
 268{
 269        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 270
 271        return sprintf(buf, "%d\n", fan_data->speed[0].rpm);
 272}
 273
 274static ssize_t show_rpm_max(struct device *dev,
 275                            struct device_attribute *attr, char *buf)
 276{
 277        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 278
 279        return sprintf(buf, "%d\n",
 280                       fan_data->speed[fan_data->num_speed - 1].rpm);
 281}
 282
 283static ssize_t show_rpm(struct device *dev,
 284                        struct device_attribute *attr, char *buf)
 285{
 286        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 287
 288        return sprintf(buf, "%d\n", fan_data->speed[fan_data->speed_index].rpm);
 289}
 290
 291static ssize_t set_rpm(struct device *dev, struct device_attribute *attr,
 292                       const char *buf, size_t count)
 293{
 294        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 295        unsigned long rpm;
 296        int ret = count;
 297
 298        if (kstrtoul(buf, 10, &rpm))
 299                return -EINVAL;
 300
 301        mutex_lock(&fan_data->lock);
 302
 303        if (!fan_data->pwm_enable) {
 304                ret = -EPERM;
 305                goto exit_unlock;
 306        }
 307
 308        set_fan_speed(fan_data, rpm_to_speed_index(fan_data, rpm));
 309
 310exit_unlock:
 311        mutex_unlock(&fan_data->lock);
 312
 313        return ret;
 314}
 315
 316static DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm);
 317static DEVICE_ATTR(pwm1_enable, S_IRUGO | S_IWUSR,
 318                   show_pwm_enable, set_pwm_enable);
 319static DEVICE_ATTR(pwm1_mode, S_IRUGO, show_pwm_mode, NULL);
 320static DEVICE_ATTR(fan1_min, S_IRUGO, show_rpm_min, NULL);
 321static DEVICE_ATTR(fan1_max, S_IRUGO, show_rpm_max, NULL);
 322static DEVICE_ATTR(fan1_input, S_IRUGO, show_rpm, NULL);
 323static DEVICE_ATTR(fan1_target, S_IRUGO | S_IWUSR, show_rpm, set_rpm);
 324
 325static umode_t gpio_fan_is_visible(struct kobject *kobj,
 326                                   struct attribute *attr, int index)
 327{
 328        struct device *dev = container_of(kobj, struct device, kobj);
 329        struct gpio_fan_data *data = dev_get_drvdata(dev);
 330
 331        if (index == 0 && !data->alarm)
 332                return 0;
 333        if (index > 0 && !data->ctrl)
 334                return 0;
 335
 336        return attr->mode;
 337}
 338
 339static struct attribute *gpio_fan_attributes[] = {
 340        &dev_attr_fan1_alarm.attr,              /* 0 */
 341        &dev_attr_pwm1.attr,                    /* 1 */
 342        &dev_attr_pwm1_enable.attr,
 343        &dev_attr_pwm1_mode.attr,
 344        &dev_attr_fan1_input.attr,
 345        &dev_attr_fan1_target.attr,
 346        &dev_attr_fan1_min.attr,
 347        &dev_attr_fan1_max.attr,
 348        NULL
 349};
 350
 351static const struct attribute_group gpio_fan_group = {
 352        .attrs = gpio_fan_attributes,
 353        .is_visible = gpio_fan_is_visible,
 354};
 355
 356static const struct attribute_group *gpio_fan_groups[] = {
 357        &gpio_fan_group,
 358        NULL
 359};
 360
 361static int fan_ctrl_init(struct gpio_fan_data *fan_data,
 362                         struct gpio_fan_platform_data *pdata)
 363{
 364        struct platform_device *pdev = fan_data->pdev;
 365        int num_ctrl = pdata->num_ctrl;
 366        unsigned *ctrl = pdata->ctrl;
 367        int i, err;
 368
 369        for (i = 0; i < num_ctrl; i++) {
 370                err = devm_gpio_request(&pdev->dev, ctrl[i],
 371                                        "GPIO fan control");
 372                if (err)
 373                        return err;
 374
 375                err = gpio_direction_output(ctrl[i],
 376                                            gpio_get_value_cansleep(ctrl[i]));
 377                if (err)
 378                        return err;
 379        }
 380
 381        fan_data->num_ctrl = num_ctrl;
 382        fan_data->ctrl = ctrl;
 383        fan_data->num_speed = pdata->num_speed;
 384        fan_data->speed = pdata->speed;
 385        fan_data->pwm_enable = true; /* Enable manual fan speed control. */
 386        fan_data->speed_index = get_fan_speed_index(fan_data);
 387        if (fan_data->speed_index < 0)
 388                return fan_data->speed_index;
 389
 390        return 0;
 391}
 392
 393static int gpio_fan_get_max_state(struct thermal_cooling_device *cdev,
 394                                  unsigned long *state)
 395{
 396        struct gpio_fan_data *fan_data = cdev->devdata;
 397
 398        if (!fan_data)
 399                return -EINVAL;
 400
 401        *state = fan_data->num_speed - 1;
 402        return 0;
 403}
 404
 405static int gpio_fan_get_cur_state(struct thermal_cooling_device *cdev,
 406                                  unsigned long *state)
 407{
 408        struct gpio_fan_data *fan_data = cdev->devdata;
 409
 410        if (!fan_data)
 411                return -EINVAL;
 412
 413        *state = fan_data->speed_index;
 414        return 0;
 415}
 416
 417static int gpio_fan_set_cur_state(struct thermal_cooling_device *cdev,
 418                                  unsigned long state)
 419{
 420        struct gpio_fan_data *fan_data = cdev->devdata;
 421
 422        if (!fan_data)
 423                return -EINVAL;
 424
 425        set_fan_speed(fan_data, state);
 426        return 0;
 427}
 428
 429static const struct thermal_cooling_device_ops gpio_fan_cool_ops = {
 430        .get_max_state = gpio_fan_get_max_state,
 431        .get_cur_state = gpio_fan_get_cur_state,
 432        .set_cur_state = gpio_fan_set_cur_state,
 433};
 434
 435#ifdef CONFIG_OF_GPIO
 436/*
 437 * Translate OpenFirmware node properties into platform_data
 438 */
 439static int gpio_fan_get_of_pdata(struct device *dev,
 440                            struct gpio_fan_platform_data *pdata)
 441{
 442        struct device_node *node;
 443        struct gpio_fan_speed *speed;
 444        unsigned *ctrl;
 445        unsigned i;
 446        u32 u;
 447        struct property *prop;
 448        const __be32 *p;
 449
 450        node = dev->of_node;
 451
 452        /* Alarm GPIO if one exists */
 453        if (of_gpio_named_count(node, "alarm-gpios") > 0) {
 454                struct gpio_fan_alarm *alarm;
 455                int val;
 456                enum of_gpio_flags flags;
 457
 458                alarm = devm_kzalloc(dev, sizeof(struct gpio_fan_alarm),
 459                                        GFP_KERNEL);
 460                if (!alarm)
 461                        return -ENOMEM;
 462
 463                val = of_get_named_gpio_flags(node, "alarm-gpios", 0, &flags);
 464                if (val < 0)
 465                        return val;
 466                alarm->gpio = val;
 467                alarm->active_low = flags & OF_GPIO_ACTIVE_LOW;
 468
 469                pdata->alarm = alarm;
 470        }
 471
 472        /* Fill GPIO pin array */
 473        pdata->num_ctrl = of_gpio_count(node);
 474        if (pdata->num_ctrl <= 0) {
 475                if (pdata->alarm)
 476                        return 0;
 477                dev_err(dev, "DT properties empty / missing");
 478                return -ENODEV;
 479        }
 480        ctrl = devm_kzalloc(dev, pdata->num_ctrl * sizeof(unsigned),
 481                                GFP_KERNEL);
 482        if (!ctrl)
 483                return -ENOMEM;
 484        for (i = 0; i < pdata->num_ctrl; i++) {
 485                int val;
 486
 487                val = of_get_gpio(node, i);
 488                if (val < 0)
 489                        return val;
 490                ctrl[i] = val;
 491        }
 492        pdata->ctrl = ctrl;
 493
 494        /* Get number of RPM/ctrl_val pairs in speed map */
 495        prop = of_find_property(node, "gpio-fan,speed-map", &i);
 496        if (!prop) {
 497                dev_err(dev, "gpio-fan,speed-map DT property missing");
 498                return -ENODEV;
 499        }
 500        i = i / sizeof(u32);
 501        if (i == 0 || i & 1) {
 502                dev_err(dev, "gpio-fan,speed-map contains zero/odd number of entries");
 503                return -ENODEV;
 504        }
 505        pdata->num_speed = i / 2;
 506
 507        /*
 508         * Populate speed map
 509         * Speed map is in the form <RPM ctrl_val RPM ctrl_val ...>
 510         * this needs splitting into pairs to create gpio_fan_speed structs
 511         */
 512        speed = devm_kzalloc(dev,
 513                        pdata->num_speed * sizeof(struct gpio_fan_speed),
 514                        GFP_KERNEL);
 515        if (!speed)
 516                return -ENOMEM;
 517        p = NULL;
 518        for (i = 0; i < pdata->num_speed; i++) {
 519                p = of_prop_next_u32(prop, p, &u);
 520                if (!p)
 521                        return -ENODEV;
 522                speed[i].rpm = u;
 523                p = of_prop_next_u32(prop, p, &u);
 524                if (!p)
 525                        return -ENODEV;
 526                speed[i].ctrl_val = u;
 527        }
 528        pdata->speed = speed;
 529
 530        return 0;
 531}
 532
 533static const struct of_device_id of_gpio_fan_match[] = {
 534        { .compatible = "gpio-fan", },
 535        {},
 536};
 537MODULE_DEVICE_TABLE(of, of_gpio_fan_match);
 538#endif /* CONFIG_OF_GPIO */
 539
 540static int gpio_fan_probe(struct platform_device *pdev)
 541{
 542        int err;
 543        struct gpio_fan_data *fan_data;
 544        struct gpio_fan_platform_data *pdata = dev_get_platdata(&pdev->dev);
 545
 546        fan_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_fan_data),
 547                                GFP_KERNEL);
 548        if (!fan_data)
 549                return -ENOMEM;
 550
 551#ifdef CONFIG_OF_GPIO
 552        if (!pdata) {
 553                pdata = devm_kzalloc(&pdev->dev,
 554                                        sizeof(struct gpio_fan_platform_data),
 555                                        GFP_KERNEL);
 556                if (!pdata)
 557                        return -ENOMEM;
 558
 559                err = gpio_fan_get_of_pdata(&pdev->dev, pdata);
 560                if (err)
 561                        return err;
 562        }
 563#else /* CONFIG_OF_GPIO */
 564        if (!pdata)
 565                return -EINVAL;
 566#endif /* CONFIG_OF_GPIO */
 567
 568        fan_data->pdev = pdev;
 569        platform_set_drvdata(pdev, fan_data);
 570        mutex_init(&fan_data->lock);
 571
 572        /* Configure alarm GPIO if available. */
 573        if (pdata->alarm) {
 574                err = fan_alarm_init(fan_data, pdata->alarm);
 575                if (err)
 576                        return err;
 577        }
 578
 579        /* Configure control GPIOs if available. */
 580        if (pdata->ctrl && pdata->num_ctrl > 0) {
 581                if (!pdata->speed || pdata->num_speed <= 1)
 582                        return -EINVAL;
 583                err = fan_ctrl_init(fan_data, pdata);
 584                if (err)
 585                        return err;
 586        }
 587
 588        /* Make this driver part of hwmon class. */
 589        fan_data->hwmon_dev =
 590                devm_hwmon_device_register_with_groups(&pdev->dev,
 591                                                       "gpio_fan", fan_data,
 592                                                       gpio_fan_groups);
 593        if (IS_ERR(fan_data->hwmon_dev))
 594                return PTR_ERR(fan_data->hwmon_dev);
 595#ifdef CONFIG_OF_GPIO
 596        /* Optional cooling device register for Device tree platforms */
 597        fan_data->cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
 598                                                            "gpio-fan",
 599                                                            fan_data,
 600                                                            &gpio_fan_cool_ops);
 601#else /* CONFIG_OF_GPIO */
 602        /* Optional cooling device register for non Device tree platforms */
 603        fan_data->cdev = thermal_cooling_device_register("gpio-fan", fan_data,
 604                                                         &gpio_fan_cool_ops);
 605#endif /* CONFIG_OF_GPIO */
 606
 607        dev_info(&pdev->dev, "GPIO fan initialized\n");
 608
 609        return 0;
 610}
 611
 612static int gpio_fan_remove(struct platform_device *pdev)
 613{
 614        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);
 615
 616        if (!IS_ERR(fan_data->cdev))
 617                thermal_cooling_device_unregister(fan_data->cdev);
 618
 619        if (fan_data->ctrl)
 620                set_fan_speed(fan_data, 0);
 621
 622        return 0;
 623}
 624
 625static void gpio_fan_shutdown(struct platform_device *pdev)
 626{
 627        gpio_fan_remove(pdev);
 628}
 629
 630#ifdef CONFIG_PM_SLEEP
 631static int gpio_fan_suspend(struct device *dev)
 632{
 633        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 634
 635        if (fan_data->ctrl) {
 636                fan_data->resume_speed = fan_data->speed_index;
 637                set_fan_speed(fan_data, 0);
 638        }
 639
 640        return 0;
 641}
 642
 643static int gpio_fan_resume(struct device *dev)
 644{
 645        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 646
 647        if (fan_data->ctrl)
 648                set_fan_speed(fan_data, fan_data->resume_speed);
 649
 650        return 0;
 651}
 652
 653static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
 654#define GPIO_FAN_PM     (&gpio_fan_pm)
 655#else
 656#define GPIO_FAN_PM     NULL
 657#endif
 658
 659static struct platform_driver gpio_fan_driver = {
 660        .probe          = gpio_fan_probe,
 661        .remove         = gpio_fan_remove,
 662        .shutdown       = gpio_fan_shutdown,
 663        .driver = {
 664                .name   = "gpio-fan",
 665                .pm     = GPIO_FAN_PM,
 666#ifdef CONFIG_OF_GPIO
 667                .of_match_table = of_match_ptr(of_gpio_fan_match),
 668#endif
 669        },
 670};
 671
 672module_platform_driver(gpio_fan_driver);
 673
 674MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
 675MODULE_DESCRIPTION("GPIO FAN driver");
 676MODULE_LICENSE("GPL");
 677MODULE_ALIAS("platform:gpio-fan");
 678