[deliverable/linux.git] / drivers / thermal / thermal_core.c

/*
 *  thermal.c - Generic Thermal Management Sysfs support.
 *
 *  Copyright (C) 2008 Intel Corp
 *  Copyright (C) 2008 Zhang Rui <rui.zhang@intel.com>
 *  Copyright (C) 2008 Sujith Thomas <sujith.thomas@intel.com>
 *
 *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/kdev_t.h>
#include <linux/idr.h>
#include <linux/thermal.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <net/netlink.h>
#include <net/genetlink.h>

#include "thermal_core.h"
#include "thermal_hwmon.h"

MODULE_AUTHOR("Zhang Rui");
MODULE_DESCRIPTION("Generic thermal management sysfs support");
MODULE_LICENSE("GPL v2");

static DEFINE_IDR(thermal_tz_idr);
static DEFINE_IDR(thermal_cdev_idr);
static DEFINE_MUTEX(thermal_idr_lock);

static LIST_HEAD(thermal_tz_list);
static LIST_HEAD(thermal_cdev_list);
static LIST_HEAD(thermal_governor_list);

static DEFINE_MUTEX(thermal_list_lock);
static DEFINE_MUTEX(thermal_governor_lock);

static struct thermal_governor *__find_governor(const char *name)
{
        struct thermal_governor *pos;

        list_for_each_entry(pos, &thermal_governor_list, governor_list)
                if (!strnicmp(name, pos->name, THERMAL_NAME_LENGTH))
                        return pos;

        return NULL;
}

int thermal_register_governor(struct thermal_governor *governor)
{
        int err;
        const char *name;
        struct thermal_zone_device *pos;

        if (!governor)
                return -EINVAL;

        mutex_lock(&thermal_governor_lock);

        err = -EBUSY;
        if (__find_governor(governor->name) == NULL) {
                err = 0;
                list_add(&governor->governor_list, &thermal_governor_list);
        }

        mutex_lock(&thermal_list_lock);

        list_for_each_entry(pos, &thermal_tz_list, node) {
                if (pos->governor)
                        continue;
                if (pos->tzp)
                        name = pos->tzp->governor_name;
                else
                        name = DEFAULT_THERMAL_GOVERNOR;
                if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH))
                        pos->governor = governor;
        }

        mutex_unlock(&thermal_list_lock);
        mutex_unlock(&thermal_governor_lock);

        return err;
}

void thermal_unregister_governor(struct thermal_governor *governor)
{
        struct thermal_zone_device *pos;

        if (!governor)
                return;

        mutex_lock(&thermal_governor_lock);

        if (__find_governor(governor->name) == NULL)
                goto exit;

        mutex_lock(&thermal_list_lock);

        list_for_each_entry(pos, &thermal_tz_list, node) {
                if (!strnicmp(pos->governor->name, governor->name,
                                                THERMAL_NAME_LENGTH))
                        pos->governor = NULL;
        }

        mutex_unlock(&thermal_list_lock);
        list_del(&governor->governor_list);
exit:
        mutex_unlock(&thermal_governor_lock);
        return;
}

static int get_idr(struct idr *idr, struct mutex *lock, int *id)
{
        int ret;

        if (lock)
                mutex_lock(lock);
        ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
        if (lock)
                mutex_unlock(lock);
        if (unlikely(ret < 0))
                return ret;
        *id = ret;
        return 0;
}

static void release_idr(struct idr *idr, struct mutex *lock, int id)
{
        if (lock)
                mutex_lock(lock);
        idr_remove(idr, id);
        if (lock)
                mutex_unlock(lock);
}

int get_tz_trend(struct thermal_zone_device *tz, int trip)
{
        enum thermal_trend trend;

        if (tz->emul_temperature || !tz->ops->get_trend ||
            tz->ops->get_trend(tz, trip, &trend)) {
                if (tz->temperature > tz->last_temperature)
                        trend = THERMAL_TREND_RAISING;
                else if (tz->temperature < tz->last_temperature)
                        trend = THERMAL_TREND_DROPPING;
                else
                        trend = THERMAL_TREND_STABLE;
        }

        return trend;
}
EXPORT_SYMBOL(get_tz_trend);

struct thermal_instance *get_thermal_instance(struct thermal_zone_device *tz,
                        struct thermal_cooling_device *cdev, int trip)
{
        struct thermal_instance *pos = NULL;
        struct thermal_instance *target_instance = NULL;

        mutex_lock(&tz->lock);
        mutex_lock(&cdev->lock);

        list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
                if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
                        target_instance = pos;
                        break;
                }
        }

        mutex_unlock(&cdev->lock);
        mutex_unlock(&tz->lock);

        return target_instance;
}
EXPORT_SYMBOL(get_thermal_instance);

static void print_bind_err_msg(struct thermal_zone_device *tz,
                        struct thermal_cooling_device *cdev, int ret)
{
        dev_err(&tz->device, "binding zone %s with cdev %s failed:%d\n",
                                tz->type, cdev->type, ret);
}

static void __bind(struct thermal_zone_device *tz, int mask,
                        struct thermal_cooling_device *cdev,
                        unsigned long *limits)
{
        int i, ret;

        for (i = 0; i < tz->trips; i++) {
                if (mask & (1 << i)) {
                        unsigned long upper, lower;

                        upper = THERMAL_NO_LIMIT;
                        lower = THERMAL_NO_LIMIT;
                        if (limits) {
                                lower = limits[i * 2];
                                upper = limits[i * 2 + 1];
                        }
                        ret = thermal_zone_bind_cooling_device(tz, i, cdev,
                                                               upper, lower);
                        if (ret)
                                print_bind_err_msg(tz, cdev, ret);
                }
        }
}

static void __unbind(struct thermal_zone_device *tz, int mask,
                        struct thermal_cooling_device *cdev)
{
        int i;

        for (i = 0; i < tz->trips; i++)
                if (mask & (1 << i))
                        thermal_zone_unbind_cooling_device(tz, i, cdev);
}

static void bind_cdev(struct thermal_cooling_device *cdev)
{
        int i, ret;
        const struct thermal_zone_params *tzp;
        struct thermal_zone_device *pos = NULL;

        mutex_lock(&thermal_list_lock);

        list_for_each_entry(pos, &thermal_tz_list, node) {
                if (!pos->tzp && !pos->ops->bind)
                        continue;

                if (!pos->tzp && pos->ops->bind) {
                        ret = pos->ops->bind(pos, cdev);
                        if (ret)
                                print_bind_err_msg(pos, cdev, ret);
                }

                tzp = pos->tzp;
                if (!tzp || !tzp->tbp)
                        continue;

                for (i = 0; i < tzp->num_tbps; i++) {
                        if (tzp->tbp[i].cdev || !tzp->tbp[i].match)
                                continue;
                        if (tzp->tbp[i].match(pos, cdev))
                                continue;
                        tzp->tbp[i].cdev = cdev;
                        __bind(pos, tzp->tbp[i].trip_mask, cdev,
                               tzp->tbp[i].binding_limits);
                }
        }

        mutex_unlock(&thermal_list_lock);
}

static void bind_tz(struct thermal_zone_device *tz)
{
        int i, ret;
        struct thermal_cooling_device *pos = NULL;
        const struct thermal_zone_params *tzp = tz->tzp;

        if (!tzp && !tz->ops->bind)
                return;

        mutex_lock(&thermal_list_lock);

        /* If there is no platform data, try to use ops->bind */
        if (!tzp && tz->ops->bind) {
                list_for_each_entry(pos, &thermal_cdev_list, node) {
                        ret = tz->ops->bind(tz, pos);
                        if (ret)
                                print_bind_err_msg(tz, pos, ret);
                }
                goto exit;
        }

        if (!tzp || !tzp->tbp)
                goto exit;

        list_for_each_entry(pos, &thermal_cdev_list, node) {
                for (i = 0; i < tzp->num_tbps; i++) {
                        if (tzp->tbp[i].cdev || !tzp->tbp[i].match)
                                continue;
                        if (tzp->tbp[i].match(tz, pos))
                                continue;
                        tzp->tbp[i].cdev = pos;
                        __bind(tz, tzp->tbp[i].trip_mask, pos,
                               tzp->tbp[i].binding_limits);
                }
        }
exit:
        mutex_unlock(&thermal_list_lock);
}

static void thermal_zone_device_set_polling(struct thermal_zone_device *tz,
                                            int delay)
{
        if (delay > 1000)
                mod_delayed_work(system_freezable_wq, &tz->poll_queue,
                                 round_jiffies(msecs_to_jiffies(delay)));
        else if (delay)
                mod_delayed_work(system_freezable_wq, &tz->poll_queue,
                                 msecs_to_jiffies(delay));
        else
                cancel_delayed_work(&tz->poll_queue);
}

static void monitor_thermal_zone(struct thermal_zone_device *tz)
{
        mutex_lock(&tz->lock);

        if (tz->passive)
                thermal_zone_device_set_polling(tz, tz->passive_delay);
        else if (tz->polling_delay)
                thermal_zone_device_set_polling(tz, tz->polling_delay);
        else
                thermal_zone_device_set_polling(tz, 0);

        mutex_unlock(&tz->lock);
}

static void handle_non_critical_trips(struct thermal_zone_device *tz,
                        int trip, enum thermal_trip_type trip_type)
{
        if (tz->governor)
                tz->governor->throttle(tz, trip);
}

static void handle_critical_trips(struct thermal_zone_device *tz,
                                int trip, enum thermal_trip_type trip_type)
{
        long trip_temp;

        tz->ops->get_trip_temp(tz, trip, &trip_temp);

        /* If we have not crossed the trip_temp, we do not care. */
        if (tz->temperature < trip_temp)
                return;

        if (tz->ops->notify)
                tz->ops->notify(tz, trip, trip_type);

        if (trip_type == THERMAL_TRIP_CRITICAL) {
                dev_emerg(&tz->device,
                          "critical temperature reached(%d C),shutting down\n",
                          tz->temperature / 1000);
                orderly_poweroff(true);
        }
}

static void handle_thermal_trip(struct thermal_zone_device *tz, int trip)
{
        enum thermal_trip_type type;

        tz->ops->get_trip_type(tz, trip, &type);

        if (type == THERMAL_TRIP_CRITICAL || type == THERMAL_TRIP_HOT)
                handle_critical_trips(tz, trip, type);
        else
                handle_non_critical_trips(tz, trip, type);
        /*
         * Alright, we handled this trip successfully.
         * So, start monitoring again.
         */
        monitor_thermal_zone(tz);
}

/**
 * thermal_zone_get_temp() - returns its the temperature of thermal zone
 * @tz: a valid pointer to a struct thermal_zone_device
 * @temp: a valid pointer to where to store the resulting temperature.
 *
 * When a valid thermal zone reference is passed, it will fetch its
 * temperature and fill @temp.
 *
 * Return: On success returns 0, an error code otherwise
 */
int thermal_zone_get_temp(struct thermal_zone_device *tz, unsigned long *temp)
{
        int ret = -EINVAL;
#ifdef CONFIG_THERMAL_EMULATION
        int count;
        unsigned long crit_temp = -1UL;
        enum thermal_trip_type type;
#endif

        if (!tz || IS_ERR(tz))
                goto exit;

        mutex_lock(&tz->lock);

        ret = tz->ops->get_temp(tz, temp);
#ifdef CONFIG_THERMAL_EMULATION
        if (!tz->emul_temperature)
                goto skip_emul;

        for (count = 0; count < tz->trips; count++) {
                ret = tz->ops->get_trip_type(tz, count, &type);
                if (!ret && type == THERMAL_TRIP_CRITICAL) {
                        ret = tz->ops->get_trip_temp(tz, count, &crit_temp);
                        break;
                }
        }

        if (ret)
                goto skip_emul;

        if (*temp < crit_temp)
                *temp = tz->emul_temperature;
skip_emul:
#endif
        mutex_unlock(&tz->lock);
exit:
        return ret;
}
EXPORT_SYMBOL_GPL(thermal_zone_get_temp);

static void update_temperature(struct thermal_zone_device *tz)
{
        long temp;
        int ret;

        ret = thermal_zone_get_temp(tz, &temp);
        if (ret) {
                dev_warn(&tz->device, "failed to read out thermal zone %d\n",
                         tz->id);
                return;
        }

        mutex_lock(&tz->lock);
        tz->last_temperature = tz->temperature;
        tz->temperature = temp;
        mutex_unlock(&tz->lock);
}

void thermal_zone_device_update(struct thermal_zone_device *tz)
{
        int count;

        update_temperature(tz);

        for (count = 0; count < tz->trips; count++)
                handle_thermal_trip(tz, count);
}
EXPORT_SYMBOL_GPL(thermal_zone_device_update);

static void thermal_zone_device_check(struct work_struct *work)
{
        struct thermal_zone_device *tz = container_of(work, struct
                                                      thermal_zone_device,
                                                      poll_queue.work);
        thermal_zone_device_update(tz);
}

/* sys I/F for thermal zone */

#define to_thermal_zone(_dev) \
        container_of(_dev, struct thermal_zone_device, device)

static ssize_t
type_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);

        return sprintf(buf, "%s\n", tz->type);
}

static ssize_t
temp_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        long temperature;
        int ret;

        ret = thermal_zone_get_temp(tz, &temperature);

        if (ret)
                return ret;

        return sprintf(buf, "%ld\n", temperature);
}

static ssize_t
mode_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        enum thermal_device_mode mode;
        int result;

        if (!tz->ops->get_mode)
                return -EPERM;

        result = tz->ops->get_mode(tz, &mode);
        if (result)
                return result;

        return sprintf(buf, "%s\n", mode == THERMAL_DEVICE_ENABLED ? "enabled"
                       : "disabled");
}

static ssize_t
mode_store(struct device *dev, struct device_attribute *attr,
           const char *buf, size_t count)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        int result;

        if (!tz->ops->set_mode)
                return -EPERM;

        if (!strncmp(buf, "enabled", sizeof("enabled") - 1))
                result = tz->ops->set_mode(tz, THERMAL_DEVICE_ENABLED);
        else if (!strncmp(buf, "disabled", sizeof("disabled") - 1))
                result = tz->ops->set_mode(tz, THERMAL_DEVICE_DISABLED);
        else
                result = -EINVAL;

        if (result)
                return result;

        return count;
}

static ssize_t
trip_point_type_show(struct device *dev, struct device_attribute *attr,
                     char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        enum thermal_trip_type type;
        int trip, result;

        if (!tz->ops->get_trip_type)
                return -EPERM;

        if (!sscanf(attr->attr.name, "trip_point_%d_type", &trip))
                return -EINVAL;

        result = tz->ops->get_trip_type(tz, trip, &type);
        if (result)
                return result;

        switch (type) {
        case THERMAL_TRIP_CRITICAL:
                return sprintf(buf, "critical\n");
        case THERMAL_TRIP_HOT:
                return sprintf(buf, "hot\n");
        case THERMAL_TRIP_PASSIVE:
                return sprintf(buf, "passive\n");
        case THERMAL_TRIP_ACTIVE:
                return sprintf(buf, "active\n");
        default:
                return sprintf(buf, "unknown\n");
        }
}

static ssize_t
trip_point_temp_store(struct device *dev, struct device_attribute *attr,
                     const char *buf, size_t count)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        int trip, ret;
        unsigned long temperature;

        if (!tz->ops->set_trip_temp)
                return -EPERM;

        if (!sscanf(attr->attr.name, "trip_point_%d_temp", &trip))
                return -EINVAL;

        if (kstrtoul(buf, 10, &temperature))
                return -EINVAL;

        ret = tz->ops->set_trip_temp(tz, trip, temperature);

        return ret ? ret : count;
}

static ssize_t
trip_point_temp_show(struct device *dev, struct device_attribute *attr,
                     char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        int trip, ret;
        long temperature;

        if (!tz->ops->get_trip_temp)
                return -EPERM;

        if (!sscanf(attr->attr.name, "trip_point_%d_temp", &trip))
                return -EINVAL;

        ret = tz->ops->get_trip_temp(tz, trip, &temperature);

        if (ret)
                return ret;

        return sprintf(buf, "%ld\n", temperature);
}

static ssize_t
trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
                        const char *buf, size_t count)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        int trip, ret;
        unsigned long temperature;

        if (!tz->ops->set_trip_hyst)
                return -EPERM;

        if (!sscanf(attr->attr.name, "trip_point_%d_hyst", &trip))
                return -EINVAL;

        if (kstrtoul(buf, 10, &temperature))
                return -EINVAL;

        /*
         * We are not doing any check on the 'temperature' value
         * here. The driver implementing 'set_trip_hyst' has to
         * take care of this.
         */
        ret = tz->ops->set_trip_hyst(tz, trip, temperature);

        return ret ? ret : count;
}

static ssize_t
trip_point_hyst_show(struct device *dev, struct device_attribute *attr,
                        char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        int trip, ret;
        unsigned long temperature;

        if (!tz->ops->get_trip_hyst)
                return -EPERM;

        if (!sscanf(attr->attr.name, "trip_point_%d_hyst", &trip))
                return -EINVAL;

        ret = tz->ops->get_trip_hyst(tz, trip, &temperature);

        return ret ? ret : sprintf(buf, "%ld\n", temperature);
}

static ssize_t
passive_store(struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        struct thermal_cooling_device *cdev = NULL;
        int state;

        if (!sscanf(buf, "%d\n", &state))
                return -EINVAL;

        /* sanity check: values below 1000 millicelcius don't make sense
         * and can cause the system to go into a thermal heart attack
         */
        if (state && state < 1000)
                return -EINVAL;

        if (state && !tz->forced_passive) {
                mutex_lock(&thermal_list_lock);
                list_for_each_entry(cdev, &thermal_cdev_list, node) {
                        if (!strncmp("Processor", cdev->type,
                                     sizeof("Processor")))
                                thermal_zone_bind_cooling_device(tz,
                                                THERMAL_TRIPS_NONE, cdev,
                                                THERMAL_NO_LIMIT,
                                                THERMAL_NO_LIMIT);
                }
                mutex_unlock(&thermal_list_lock);
                if (!tz->passive_delay)
                        tz->passive_delay = 1000;
        } else if (!state && tz->forced_passive) {
                mutex_lock(&thermal_list_lock);
                list_for_each_entry(cdev, &thermal_cdev_list, node) {
                        if (!strncmp("Processor", cdev->type,
                                     sizeof("Processor")))
                                thermal_zone_unbind_cooling_device(tz,
                                                                   THERMAL_TRIPS_NONE,
                                                                   cdev);
                }
                mutex_unlock(&thermal_list_lock);
                tz->passive_delay = 0;
        }

        tz->forced_passive = state;

        thermal_zone_device_update(tz);

        return count;
}

static ssize_t
passive_show(struct device *dev, struct device_attribute *attr,
                   char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);

        return sprintf(buf, "%d\n", tz->forced_passive);
}

static ssize_t
policy_store(struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        int ret = -EINVAL;
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        struct thermal_governor *gov;
        char name[THERMAL_NAME_LENGTH];

        snprintf(name, sizeof(name), "%s", buf);

        mutex_lock(&thermal_governor_lock);

        gov = __find_governor(strim(name));
        if (!gov)
                goto exit;

        tz->governor = gov;
        ret = count;

exit:
        mutex_unlock(&thermal_governor_lock);
        return ret;
}

static ssize_t
policy_show(struct device *dev, struct device_attribute *devattr, char *buf)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);

        return sprintf(buf, "%s\n", tz->governor->name);
}

#ifdef CONFIG_THERMAL_EMULATION
static ssize_t
emul_temp_store(struct device *dev, struct device_attribute *attr,
                     const char *buf, size_t count)
{
        struct thermal_zone_device *tz = to_thermal_zone(dev);
        int ret = 0;
        unsigned long temperature;

        if (kstrtoul(buf, 10, &temperature))
                return -EINVAL;

        if (!tz->ops->set_emul_temp) {
                mutex_lock(&tz->lock);
                tz->emul_temperature = temperature;
                mutex_unlock(&tz->lock);
        } else {
                ret = tz->ops->set_emul_temp(tz, temperature);
        }

        return ret ? ret : count;
}
static DEVICE_ATTR(emul_temp, S_IWUSR, NULL, emul_temp_store);
#endif/*CONFIG_THERMAL_EMULATION*/

static DEVICE_ATTR(type, 0444, type_show, NULL);
static DEVICE_ATTR(temp, 0444, temp_show, NULL);
static DEVICE_ATTR(mode, 0644, mode_show, mode_store);
static DEVICE_ATTR(passive, S_IRUGO | S_IWUSR, passive_show, passive_store);
static DEVICE_ATTR(policy, S_IRUGO | S_IWUSR, policy_show, policy_store);

/* sys I/F for cooling device */
#define to_cooling_device(_dev) \
        container_of(_dev, struct thermal_cooling_device, device)

static ssize_t
thermal_cooling_device_type_show(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct thermal_cooling_device *cdev = to_cooling_device(dev);

        return sprintf(buf, "%s\n", cdev->type);
}

static ssize_t
thermal_cooling_device_max_state_show(struct device *dev,
                                      struct device_attribute *attr, char *buf)
{
        struct thermal_cooling_device *cdev = to_cooling_device(dev);
        unsigned long state;
        int ret;

        ret = cdev->ops->get_max_state(cdev, &state);
        if (ret)
                return ret;
        return sprintf(buf, "%ld\n", state);
}

static ssize_t
thermal_cooling_device_cur_state_show(struct device *dev,
                                      struct device_attribute *attr, char *buf)
{
        struct thermal_cooling_device *cdev = to_cooling_device(dev);
        unsigned long state;
        int ret;

        ret = cdev->ops->get_cur_state(cdev, &state);
        if (ret)
                return ret;
        return sprintf(buf, "%ld\n", state);
}

static ssize_t
thermal_cooling_device_cur_state_store(struct device *dev,
                                       struct device_attribute *attr,
                                       const char *buf, size_t count)
{
        struct thermal_cooling_device *cdev = to_cooling_device(dev);
        unsigned long state;
        int result;

        if (!sscanf(buf, "%ld\n", &state))
                return -EINVAL;

        if ((long)state < 0)
                return -EINVAL;

        result = cdev->ops->set_cur_state(cdev, state);
        if (result)
                return result;
        return count;
}

static struct device_attribute dev_attr_cdev_type =
__ATTR(type, 0444, thermal_cooling_device_type_show, NULL);
static DEVICE_ATTR(max_state, 0444,
                   thermal_cooling_device_max_state_show, NULL);
static DEVICE_ATTR(cur_state, 0644,
                   thermal_cooling_device_cur_state_show,
                   thermal_cooling_device_cur_state_store);

static ssize_t
thermal_cooling_device_trip_point_show(struct device *dev,
                                       struct device_attribute *attr, char *buf)
{
        struct thermal_instance *instance;

        instance =
            container_of(attr, struct thermal_instance, attr);

        if (instance->trip == THERMAL_TRIPS_NONE)
                return sprintf(buf, "-1\n");
        else
                return sprintf(buf, "%d\n", instance->trip);
}

/* Device management */

/**
 * thermal_zone_bind_cooling_device() - bind a cooling device to a thermal zone
 * @tz:         pointer to struct thermal_zone_device
 * @trip:       indicates which trip point the cooling devices is
 *              associated with in this thermal zone.
 * @cdev:       pointer to struct thermal_cooling_device
 * @upper:      the Maximum cooling state for this trip point.
 *              THERMAL_NO_LIMIT means no upper limit,
 *              and the cooling device can be in max_state.
 * @lower:      the Minimum cooling state can be used for this trip point.
 *              THERMAL_NO_LIMIT means no lower limit,
 *              and the cooling device can be in cooling state 0.
 *
 * This interface function bind a thermal cooling device to the certain trip
 * point of a thermal zone device.
 * This function is usually called in the thermal zone device .bind callback.
 *
 * Return: 0 on success, the proper error value otherwise.
 */
int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
                                     int trip,
                                     struct thermal_cooling_device *cdev,
                                     unsigned long upper, unsigned long lower)
{
        struct thermal_instance *dev;
        struct thermal_instance *pos;
        struct thermal_zone_device *pos1;
        struct thermal_cooling_device *pos2;
        unsigned long max_state;
        int result;

        if (trip >= tz->trips || (trip < 0 && trip != THERMAL_TRIPS_NONE))
                return -EINVAL;

        list_for_each_entry(pos1, &thermal_tz_list, node) {
                if (pos1 == tz)
                        break;
        }
        list_for_each_entry(pos2, &thermal_cdev_list, node) {
                if (pos2 == cdev)
                        break;
        }

        if (tz != pos1 || cdev != pos2)
                return -EINVAL;

        cdev->ops->get_max_state(cdev, &max_state);

        /* lower default 0, upper default max_state */
        lower = lower == THERMAL_NO_LIMIT ? 0 : lower;
        upper = upper == THERMAL_NO_LIMIT ? max_state : upper;

        if (lower > upper || upper > max_state)
                return -EINVAL;

        dev =
            kzalloc(sizeof(struct thermal_instance), GFP_KERNEL);
        if (!dev)
                return -ENOMEM;
        dev->tz = tz;
        dev->cdev = cdev;
        dev->trip = trip;
        dev->upper = upper;
        dev->lower = lower;
        dev->target = THERMAL_NO_TARGET;

        result = get_idr(&tz->idr, &tz->lock, &dev->id);
        if (result)
                goto free_mem;

        sprintf(dev->name, "cdev%d", dev->id);
        result =
            sysfs_create_link(&tz->device.kobj, &cdev->device.kobj, dev->name);
        if (result)
                goto release_idr;

        sprintf(dev->attr_name, "cdev%d_trip_point", dev->id);
        sysfs_attr_init(&dev->attr.attr);
        dev->attr.attr.name = dev->attr_name;
        dev->attr.attr.mode = 0444;
        dev->attr.show = thermal_cooling_device_trip_point_show;
        result = device_create_file(&tz->device, &dev->attr);
        if (result)
                goto remove_symbol_link;

        mutex_lock(&tz->lock);
        mutex_lock(&cdev->lock);
        list_for_each_entry(pos, &tz->thermal_instances, tz_node)
            if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
                result = -EEXIST;
                break;
        }
        if (!result) {
                list_add_tail(&dev->tz_node, &tz->thermal_instances);
                list_add_tail(&dev->cdev_node, &cdev->thermal_instances);
        }
        mutex_unlock(&cdev->lock);
        mutex_unlock(&tz->lock);

        if (!result)
                return 0;

        device_remove_file(&tz->device, &dev->attr);
remove_symbol_link:
        sysfs_remove_link(&tz->device.kobj, dev->name);
release_idr:
        release_idr(&tz->idr, &tz->lock, dev->id);
free_mem:
        kfree(dev);
        return result;
}
EXPORT_SYMBOL_GPL(thermal_zone_bind_cooling_device);

/**
 * thermal_zone_unbind_cooling_device() - unbind a cooling device from a
 *                                        thermal zone.
 * @tz:         pointer to a struct thermal_zone_device.
 * @trip:       indicates which trip point the cooling devices is
 *              associated with in this thermal zone.
 * @cdev:       pointer to a struct thermal_cooling_device.
 *
 * This interface function unbind a thermal cooling device from the certain
 * trip point of a thermal zone device.
 * This function is usually called in the thermal zone device .unbind callback.
 *
 * Return: 0 on success, the proper error value otherwise.
 */
int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
                                       int trip,
                                       struct thermal_cooling_device *cdev)
{
        struct thermal_instance *pos, *next;

        mutex_lock(&tz->lock);
        mutex_lock(&cdev->lock);
        list_for_each_entry_safe(pos, next, &tz->thermal_instances, tz_node) {
                if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
                        list_del(&pos->tz_node);
                        list_del(&pos->cdev_node);
                        mutex_unlock(&cdev->lock);
                        mutex_unlock(&tz->lock);
                        goto unbind;
                }
        }
        mutex_unlock(&cdev->lock);
        mutex_unlock(&tz->lock);

        return -ENODEV;

unbind:
        device_remove_file(&tz->device, &pos->attr);
        sysfs_remove_link(&tz->device.kobj, pos->name);
        release_idr(&tz->idr, &tz->lock, pos->id);
        kfree(pos);
        return 0;
}
EXPORT_SYMBOL_GPL(thermal_zone_unbind_cooling_device);

static void thermal_release(struct device *dev)
{
        struct thermal_zone_device *tz;
        struct thermal_cooling_device *cdev;

        if (!strncmp(dev_name(dev), "thermal_zone",
                     sizeof("thermal_zone") - 1)) {
                tz = to_thermal_zone(dev);
                kfree(tz);
        } else {
                cdev = to_cooling_device(dev);
                kfree(cdev);
        }
}

static struct class thermal_class = {
        .name = "thermal",
        .dev_release = thermal_release,
};

/**
 * thermal_cooling_device_register() - register a new thermal cooling device
 * @type:       the thermal cooling device type.
 * @devdata:    device private data.
 * @ops:                standard thermal cooling devices callbacks.
 *
 * This interface function adds a new thermal cooling device (fan/processor/...)
 * to /sys/class/thermal/ folder as cooling_device[0-*]. It tries to bind itself
 * to all the thermal zone devices registered at the same time.
 *
 * Return: a pointer to the created struct thermal_cooling_device or an
 * ERR_PTR. Caller must check return value with IS_ERR*() helpers.
 */
struct thermal_cooling_device *
thermal_cooling_device_register(char *type, void *devdata,
                                const struct thermal_cooling_device_ops *ops)
{
        struct thermal_cooling_device *cdev;
        int result;

        if (type && strlen(type) >= THERMAL_NAME_LENGTH)
                return ERR_PTR(-EINVAL);

        if (!ops || !ops->get_max_state || !ops->get_cur_state ||
            !ops->set_cur_state)
                return ERR_PTR(-EINVAL);

        cdev = kzalloc(sizeof(struct thermal_cooling_device), GFP_KERNEL);
        if (!cdev)
                return ERR_PTR(-ENOMEM);

        result = get_idr(&thermal_cdev_idr, &thermal_idr_lock, &cdev->id);
        if (result) {
                kfree(cdev);
                return ERR_PTR(result);
        }

        strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
        mutex_init(&cdev->lock);
        INIT_LIST_HEAD(&cdev->thermal_instances);
        cdev->ops = ops;
        cdev->updated = true;
        cdev->device.class = &thermal_class;
        cdev->devdata = devdata;
        dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
        result = device_register(&cdev->device);
        if (result) {
                release_idr(&thermal_cdev_idr, &thermal_idr_lock, cdev->id);
                kfree(cdev);
                return ERR_PTR(result);
        }

        /* sys I/F */
        if (type) {
                result = device_create_file(&cdev->device, &dev_attr_cdev_type);
                if (result)
                        goto unregister;
        }

        result = device_create_file(&cdev->device, &dev_attr_max_state);
        if (result)
                goto unregister;

        result = device_create_file(&cdev->device, &dev_attr_cur_state);
        if (result)
                goto unregister;

        /* Add 'this' new cdev to the global cdev list */
        mutex_lock(&thermal_list_lock);
        list_add(&cdev->node, &thermal_cdev_list);
        mutex_unlock(&thermal_list_lock);

        /* Update binding information for 'this' new cdev */
        bind_cdev(cdev);

        return cdev;

unregister:
        release_idr(&thermal_cdev_idr, &thermal_idr_lock, cdev->id);
        device_unregister(&cdev->device);
        return ERR_PTR(result);
}
EXPORT_SYMBOL_GPL(thermal_cooling_device_register);

/**
 * thermal_cooling_device_unregister - removes the registered thermal cooling device
 * @cdev:       the thermal cooling device to remove.
 *
 * thermal_cooling_device_unregister() must be called when the device is no
 * longer needed.
 */
void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
{
        int i;
        const struct thermal_zone_params *tzp;
        struct thermal_zone_device *tz;
        struct thermal_cooling_device *pos = NULL;

        if (!cdev)
                return;

        mutex_lock(&thermal_list_lock);
        list_for_each_entry(pos, &thermal_cdev_list, node)
            if (pos == cdev)
                break;
        if (pos != cdev) {
                /* thermal cooling device not found */
                mutex_unlock(&thermal_list_lock);
                return;
        }
        list_del(&cdev->node);

        /* Unbind all thermal zones associated with 'this' cdev */
        list_for_each_entry(tz, &thermal_tz_list, node) {
                if (tz->ops->unbind) {
                        tz->ops->unbind(tz, cdev);
                        continue;
                }

                if (!tz->tzp || !tz->tzp->tbp)
                        continue;

                tzp = tz->tzp;
                for (i = 0; i < tzp->num_tbps; i++) {
                        if (tzp->tbp[i].cdev == cdev) {
                                __unbind(tz, tzp->tbp[i].trip_mask, cdev);
                                tzp->tbp[i].cdev = NULL;
                        }
                }
        }

        mutex_unlock(&thermal_list_lock);

        if (cdev->type[0])
                device_remove_file(&cdev->device, &dev_attr_cdev_type);
        device_remove_file(&cdev->device, &dev_attr_max_state);
        device_remove_file(&cdev->device, &dev_attr_cur_state);

        release_idr(&thermal_cdev_idr, &thermal_idr_lock, cdev->id);
        device_unregister(&cdev->device);
        return;
}
EXPORT_SYMBOL_GPL(thermal_cooling_device_unregister);

void thermal_cdev_update(struct thermal_cooling_device *cdev)
{
        struct thermal_instance *instance;
        unsigned long target = 0;

        /* cooling device is updated*/
        if (cdev->updated)
                return;

        mutex_lock(&cdev->lock);
        /* Make sure cdev enters the deepest cooling state */
        list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
                if (instance->target == THERMAL_NO_TARGET)
                        continue;
                if (instance->target > target)
                        target = instance->target;
        }
        mutex_unlock(&cdev->lock);
        cdev->ops->set_cur_state(cdev, target);
        cdev->updated = true;
}
EXPORT_SYMBOL(thermal_cdev_update);

/**
 * thermal_notify_framework - Sensor drivers use this API to notify framework
 * @tz:         thermal zone device
 * @trip:       indicates which trip point has been crossed
 *
 * This function handles the trip events from sensor drivers. It starts
 * throttling the cooling devices according to the policy configured.
 * For CRITICAL and HOT trip points, this notifies the respective drivers,
 * and does actual throttling for other trip points i.e ACTIVE and PASSIVE.
 * The throttling policy is based on the configured platform data; if no
 * platform data is provided, this uses the step_wise throttling policy.
 */
void thermal_notify_framework(struct thermal_zone_device *tz, int trip)
{
        handle_thermal_trip(tz, trip);
}
EXPORT_SYMBOL_GPL(thermal_notify_framework);

/**
 * create_trip_attrs() - create attributes for trip points
 * @tz:         the thermal zone device
 * @mask:       Writeable trip point bitmap.
 *
 * helper function to instantiate sysfs entries for every trip
 * point and its properties of a struct thermal_zone_device.
 *
 * Return: 0 on success, the proper error value otherwise.
 */
static int create_trip_attrs(struct thermal_zone_device *tz, int mask)
{
        int indx;
        int size = sizeof(struct thermal_attr) * tz->trips;

        tz->trip_type_attrs = kzalloc(size, GFP_KERNEL);
        if (!tz->trip_type_attrs)
                return -ENOMEM;

        tz->trip_temp_attrs = kzalloc(size, GFP_KERNEL);
        if (!tz->trip_temp_attrs) {
                kfree(tz->trip_type_attrs);
                return -ENOMEM;
        }

        if (tz->ops->get_trip_hyst) {
                tz->trip_hyst_attrs = kzalloc(size, GFP_KERNEL);
                if (!tz->trip_hyst_attrs) {
                        kfree(tz->trip_type_attrs);
                        kfree(tz->trip_temp_attrs);
                        return -ENOMEM;
                }
        }


        for (indx = 0; indx < tz->trips; indx++) {
                /* create trip type attribute */
                snprintf(tz->trip_type_attrs[indx].name, THERMAL_NAME_LENGTH,
                         "trip_point_%d_type", indx);

                sysfs_attr_init(&tz->trip_type_attrs[indx].attr.attr);
                tz->trip_type_attrs[indx].attr.attr.name =
                                                tz->trip_type_attrs[indx].name;
                tz->trip_type_attrs[indx].attr.attr.mode = S_IRUGO;
                tz->trip_type_attrs[indx].attr.show = trip_point_type_show;

                device_create_file(&tz->device,
                                   &tz->trip_type_attrs[indx].attr);

                /* create trip temp attribute */
                snprintf(tz->trip_temp_attrs[indx].name, THERMAL_NAME_LENGTH,
                         "trip_point_%d_temp", indx);

                sysfs_attr_init(&tz->trip_temp_attrs[indx].attr.attr);
                tz->trip_temp_attrs[indx].attr.attr.name =
                                                tz->trip_temp_attrs[indx].name;
                tz->trip_temp_attrs[indx].attr.attr.mode = S_IRUGO;
                tz->trip_temp_attrs[indx].attr.show = trip_point_temp_show;
                if (mask & (1 << indx)) {
                        tz->trip_temp_attrs[indx].attr.attr.mode |= S_IWUSR;
                        tz->trip_temp_attrs[indx].attr.store =
                                                        trip_point_temp_store;
                }

                device_create_file(&tz->device,
                                   &tz->trip_temp_attrs[indx].attr);

                /* create Optional trip hyst attribute */
                if (!tz->ops->get_trip_hyst)
                        continue;
                snprintf(tz->trip_hyst_attrs[indx].name, THERMAL_NAME_LENGTH,
                         "trip_point_%d_hyst", indx);

                sysfs_attr_init(&tz->trip_hyst_attrs[indx].attr.attr);
                tz->trip_hyst_attrs[indx].attr.attr.name =
                                        tz->trip_hyst_attrs[indx].name;
                tz->trip_hyst_attrs[indx].attr.attr.mode = S_IRUGO;
                tz->trip_hyst_attrs[indx].attr.show = trip_point_hyst_show;
                if (tz->ops->set_trip_hyst) {
                        tz->trip_hyst_attrs[indx].attr.attr.mode |= S_IWUSR;
                        tz->trip_hyst_attrs[indx].attr.store =
                                        trip_point_hyst_store;
                }

                device_create_file(&tz->device,
                                   &tz->trip_hyst_attrs[indx].attr);
        }
        return 0;
}

static void remove_trip_attrs(struct thermal_zone_device *tz)
{
        int indx;

        for (indx = 0; indx < tz->trips; indx++) {
                device_remove_file(&tz->device,
                                   &tz->trip_type_attrs[indx].attr);
                device_remove_file(&tz->device,
                                   &tz->trip_temp_attrs[indx].attr);
                if (tz->ops->get_trip_hyst)
                        device_remove_file(&tz->device,
                                  &tz->trip_hyst_attrs[indx].attr);
        }
        kfree(tz->trip_type_attrs);
        kfree(tz->trip_temp_attrs);
        kfree(tz->trip_hyst_attrs);
}

/**
 * thermal_zone_device_register() - register a new thermal zone device
 * @type:       the thermal zone device type
 * @trips:      the number of trip points the thermal zone support
 * @mask:       a bit string indicating the writeablility of trip points
 * @devdata:    private device data
 * @ops:        standard thermal zone device callbacks
 * @tzp:        thermal zone platform parameters
 * @passive_delay: number of milliseconds to wait between polls when
 *                 performing passive cooling
 * @polling_delay: number of milliseconds to wait between polls when checking
 *                 whether trip points have been crossed (0 for interrupt
 *                 driven systems)
 *
 * This interface function adds a new thermal zone device (sensor) to
 * /sys/class/thermal folder as thermal_zone[0-*]. It tries to bind all the
 * thermal cooling devices registered at the same time.
 * thermal_zone_device_unregister() must be called when the device is no
 * longer needed. The passive cooling depends on the .get_trend() return value.
 *
 * Return: a pointer to the created struct thermal_zone_device or an
 * in case of error, an ERR_PTR. Caller must check return value with
 * IS_ERR*() helpers.
 */
struct thermal_zone_device *thermal_zone_device_register(const char *type,
        int trips, int mask, void *devdata,
        const struct thermal_zone_device_ops *ops,
        const struct thermal_zone_params *tzp,
        int passive_delay, int polling_delay)
{
        struct thermal_zone_device *tz;
        enum thermal_trip_type trip_type;
        int result;
        int count;
        int passive = 0;

        if (type && strlen(type) >= THERMAL_NAME_LENGTH)
                return ERR_PTR(-EINVAL);

        if (trips > THERMAL_MAX_TRIPS || trips < 0 || mask >> trips)
                return ERR_PTR(-EINVAL);

        if (!ops || !ops->get_temp)
                return ERR_PTR(-EINVAL);

        if (trips > 0 && (!ops->get_trip_type || !ops->get_trip_temp))
                return ERR_PTR(-EINVAL);

        tz = kzalloc(sizeof(struct thermal_zone_device), GFP_KERNEL);
        if (!tz)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&tz->thermal_instances);
        idr_init(&tz->idr);
        mutex_init(&tz->lock);
        result = get_idr(&thermal_tz_idr, &thermal_idr_lock, &tz->id);
        if (result) {
                kfree(tz);
                return ERR_PTR(result);
        }

        strlcpy(tz->type, type ? : "", sizeof(tz->type));
        tz->ops = ops;
        tz->tzp = tzp;
        tz->device.class = &thermal_class;
        tz->devdata = devdata;
        tz->trips = trips;
        tz->passive_delay = passive_delay;
        tz->polling_delay = polling_delay;

        dev_set_name(&tz->device, "thermal_zone%d", tz->id);
        result = device_register(&tz->device);
        if (result) {
                release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
                kfree(tz);
                return ERR_PTR(result);
        }

        /* sys I/F */
        if (type) {
                result = device_create_file(&tz->device, &dev_attr_type);
                if (result)
                        goto unregister;
        }

        result = device_create_file(&tz->device, &dev_attr_temp);
        if (result)
                goto unregister;

        if (ops->get_mode) {
                result = device_create_file(&tz->device, &dev_attr_mode);
                if (result)
                        goto unregister;
        }

        result = create_trip_attrs(tz, mask);
        if (result)
                goto unregister;

        for (count = 0; count < trips; count++) {
                tz->ops->get_trip_type(tz, count, &trip_type);
                if (trip_type == THERMAL_TRIP_PASSIVE)
                        passive = 1;
        }

        if (!passive) {
                result = device_create_file(&tz->device, &dev_attr_passive);
                if (result)
                        goto unregister;
        }

#ifdef CONFIG_THERMAL_EMULATION
        result = device_create_file(&tz->device, &dev_attr_emul_temp);
        if (result)
                goto unregister;
#endif
        /* Create policy attribute */
        result = device_create_file(&tz->device, &dev_attr_policy);
        if (result)
                goto unregister;

        /* Update 'this' zone's governor information */
        mutex_lock(&thermal_governor_lock);

        if (tz->tzp)
                tz->governor = __find_governor(tz->tzp->governor_name);
        else
                tz->governor = __find_governor(DEFAULT_THERMAL_GOVERNOR);

        mutex_unlock(&thermal_governor_lock);

        if (!tz->tzp || !tz->tzp->no_hwmon) {
                result = thermal_add_hwmon_sysfs(tz);
                if (result)
                        goto unregister;
        }

        mutex_lock(&thermal_list_lock);
        list_add_tail(&tz->node, &thermal_tz_list);
        mutex_unlock(&thermal_list_lock);

        /* Bind cooling devices for this zone */
        bind_tz(tz);

        INIT_DELAYED_WORK(&(tz->poll_queue), thermal_zone_device_check);

        thermal_zone_device_update(tz);

        if (!result)
                return tz;

unregister:
        release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
        device_unregister(&tz->device);
        return ERR_PTR(result);
}
EXPORT_SYMBOL_GPL(thermal_zone_device_register);

/**
 * thermal_device_unregister - removes the registered thermal zone device
 * @tz: the thermal zone device to remove
 */
void thermal_zone_device_unregister(struct thermal_zone_device *tz)
{
        int i;
        const struct thermal_zone_params *tzp;
        struct thermal_cooling_device *cdev;
        struct thermal_zone_device *pos = NULL;

        if (!tz)
                return;

        tzp = tz->tzp;

        mutex_lock(&thermal_list_lock);
        list_for_each_entry(pos, &thermal_tz_list, node)
            if (pos == tz)
                break;
        if (pos != tz) {
                /* thermal zone device not found */
                mutex_unlock(&thermal_list_lock);
                return;
        }
        list_del(&tz->node);

        /* Unbind all cdevs associated with 'this' thermal zone */
        list_for_each_entry(cdev, &thermal_cdev_list, node) {
                if (tz->ops->unbind) {
                        tz->ops->unbind(tz, cdev);
                        continue;
                }

                if (!tzp || !tzp->tbp)
                        break;

                for (i = 0; i < tzp->num_tbps; i++) {
                        if (tzp->tbp[i].cdev == cdev) {
                                __unbind(tz, tzp->tbp[i].trip_mask, cdev);
                                tzp->tbp[i].cdev = NULL;
                        }
                }
        }

        mutex_unlock(&thermal_list_lock);

        thermal_zone_device_set_polling(tz, 0);

        if (tz->type[0])
                device_remove_file(&tz->device, &dev_attr_type);
        device_remove_file(&tz->device, &dev_attr_temp);
        if (tz->ops->get_mode)
                device_remove_file(&tz->device, &dev_attr_mode);
        device_remove_file(&tz->device, &dev_attr_policy);
        remove_trip_attrs(tz);
        tz->governor = NULL;

        thermal_remove_hwmon_sysfs(tz);
        release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
        idr_destroy(&tz->idr);
        mutex_destroy(&tz->lock);
        device_unregister(&tz->device);
        return;
}
EXPORT_SYMBOL_GPL(thermal_zone_device_unregister);

/**
 * thermal_zone_get_zone_by_name() - search for a zone and returns its ref
 * @name: thermal zone name to fetch the temperature
 *
 * When only one zone is found with the passed name, returns a reference to it.
 *
 * Return: On success returns a reference to an unique thermal zone with
 * matching name equals to @name, an ERR_PTR otherwise (-EINVAL for invalid
 * paramenters, -ENODEV for not found and -EEXIST for multiple matches).
 */
struct thermal_zone_device *thermal_zone_get_zone_by_name(const char *name)
{
        struct thermal_zone_device *pos = NULL, *ref = ERR_PTR(-EINVAL);
        unsigned int found = 0;

        if (!name)
                goto exit;

        mutex_lock(&thermal_list_lock);
        list_for_each_entry(pos, &thermal_tz_list, node)
                if (!strnicmp(name, pos->type, THERMAL_NAME_LENGTH)) {
                        found++;
                        ref = pos;
                }
        mutex_unlock(&thermal_list_lock);

        /* nothing has been found, thus an error code for it */
        if (found == 0)
                ref = ERR_PTR(-ENODEV);
        else if (found > 1)
        /* Success only when an unique zone is found */
                ref = ERR_PTR(-EEXIST);

exit:
        return ref;
}
EXPORT_SYMBOL_GPL(thermal_zone_get_zone_by_name);

#ifdef CONFIG_NET
static struct genl_family thermal_event_genl_family = {
        .id = GENL_ID_GENERATE,
        .name = THERMAL_GENL_FAMILY_NAME,
        .version = THERMAL_GENL_VERSION,
        .maxattr = THERMAL_GENL_ATTR_MAX,
};

static struct genl_multicast_group thermal_event_mcgrp = {
        .name = THERMAL_GENL_MCAST_GROUP_NAME,
};

int thermal_generate_netlink_event(struct thermal_zone_device *tz,
                                        enum events event)
{
        struct sk_buff *skb;
        struct nlattr *attr;
        struct thermal_genl_event *thermal_event;
        void *msg_header;
        int size;
        int result;
        static unsigned int thermal_event_seqnum;

        if (!tz)
                return -EINVAL;

        /* allocate memory */
        size = nla_total_size(sizeof(struct thermal_genl_event)) +
               nla_total_size(0);

        skb = genlmsg_new(size, GFP_ATOMIC);
        if (!skb)
                return -ENOMEM;

        /* add the genetlink message header */
        msg_header = genlmsg_put(skb, 0, thermal_event_seqnum++,
                                 &thermal_event_genl_family, 0,
                                 THERMAL_GENL_CMD_EVENT);
        if (!msg_header) {
                nlmsg_free(skb);
                return -ENOMEM;
        }

        /* fill the data */
        attr = nla_reserve(skb, THERMAL_GENL_ATTR_EVENT,
                           sizeof(struct thermal_genl_event));

        if (!attr) {
                nlmsg_free(skb);
                return -EINVAL;
        }

        thermal_event = nla_data(attr);
        if (!thermal_event) {
                nlmsg_free(skb);
                return -EINVAL;
        }

        memset(thermal_event, 0, sizeof(struct thermal_genl_event));

        thermal_event->orig = tz->id;
        thermal_event->event = event;

        /* send multicast genetlink message */
        result = genlmsg_end(skb, msg_header);
        if (result < 0) {
                nlmsg_free(skb);
                return result;
        }

        result = genlmsg_multicast(&thermal_event_genl_family, skb, 0,
                                   thermal_event_mcgrp.id, GFP_ATOMIC);
        if (result)
                dev_err(&tz->device, "Failed to send netlink event:%d", result);

        return result;
}
EXPORT_SYMBOL_GPL(thermal_generate_netlink_event);

static int genetlink_init(void)
{
        int result;

        result = genl_register_family(&thermal_event_genl_family);
        if (result)
                return result;

        result = genl_register_mc_group(&thermal_event_genl_family,
                                        &thermal_event_mcgrp);
        if (result)
                genl_unregister_family(&thermal_event_genl_family);
        return result;
}

static void genetlink_exit(void)
{
        genl_unregister_family(&thermal_event_genl_family);
}
#else /* !CONFIG_NET */
static inline int genetlink_init(void) { return 0; }
static inline void genetlink_exit(void) {}
#endif /* !CONFIG_NET */

static int __init thermal_register_governors(void)
{
        int result;

        result = thermal_gov_step_wise_register();
        if (result)
                return result;

        result = thermal_gov_fair_share_register();
        if (result)
                return result;

        return thermal_gov_user_space_register();
}

static void thermal_unregister_governors(void)
{
        thermal_gov_step_wise_unregister();
        thermal_gov_fair_share_unregister();
        thermal_gov_user_space_unregister();
}

static int __init thermal_init(void)
{
        int result;

        result = thermal_register_governors();
        if (result)
                goto error;

        result = class_register(&thermal_class);
        if (result)
                goto unregister_governors;

        result = genetlink_init();
        if (result)
                goto unregister_class;

        return 0;

unregister_governors:
        thermal_unregister_governors();
unregister_class:
        class_unregister(&thermal_class);
error:
        idr_destroy(&thermal_tz_idr);
        idr_destroy(&thermal_cdev_idr);
        mutex_destroy(&thermal_idr_lock);
        mutex_destroy(&thermal_list_lock);
        mutex_destroy(&thermal_governor_lock);
        return result;
}

static void __exit thermal_exit(void)
{
        genetlink_exit();
        class_unregister(&thermal_class);
        thermal_unregister_governors();
        idr_destroy(&thermal_tz_idr);
        idr_destroy(&thermal_cdev_idr);
        mutex_destroy(&thermal_idr_lock);
        mutex_destroy(&thermal_list_lock);
        mutex_destroy(&thermal_governor_lock);
}

fs_initcall(thermal_init);
module_exit(thermal_exit);