Linux 4.19.133

[linux/fpc-iii.git] / drivers / thermal / of-thermal.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  of-thermal.c - Generic Thermal Management device tree support.
 *
 *  Copyright (C) 2013 Texas Instruments
 *  Copyright (C) 2013 Eduardo Valentin <eduardo.valentin@ti.com>
 */
#include <linux/thermal.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/string.h>

#include "thermal_core.h"

/***   Private data structures to represent thermal device tree data ***/

/**
 * struct __thermal_bind_param - a match between trip and cooling device
 * @cooling_device: a pointer to identify the referred cooling device
 * @trip_id: the trip point index
 * @usage: the percentage (from 0 to 100) of cooling contribution
 * @min: minimum cooling state used at this trip point
 * @max: maximum cooling state used at this trip point
 */

struct __thermal_bind_params {
        struct device_node *cooling_device;
        unsigned int trip_id;
        unsigned int usage;
        unsigned long min;
        unsigned long max;
};

/**
 * struct __thermal_zone - internal representation of a thermal zone
 * @mode: current thermal zone device mode (enabled/disabled)
 * @passive_delay: polling interval while passive cooling is activated
 * @polling_delay: zone polling interval
 * @slope: slope of the temperature adjustment curve
 * @offset: offset of the temperature adjustment curve
 * @ntrips: number of trip points
 * @trips: an array of trip points (0..ntrips - 1)
 * @num_tbps: number of thermal bind params
 * @tbps: an array of thermal bind params (0..num_tbps - 1)
 * @sensor_data: sensor private data used while reading temperature and trend
 * @ops: set of callbacks to handle the thermal zone based on DT
 */

struct __thermal_zone {
        enum thermal_device_mode mode;
        int passive_delay;
        int polling_delay;
        int slope;
        int offset;

        /* trip data */
        int ntrips;
        struct thermal_trip *trips;

        /* cooling binding data */
        int num_tbps;
        struct __thermal_bind_params *tbps;

        /* sensor interface */
        void *sensor_data;
        const struct thermal_zone_of_device_ops *ops;
};

/***   DT thermal zone device callbacks   ***/

static int of_thermal_get_temp(struct thermal_zone_device *tz,
                               int *temp)
{
        struct __thermal_zone *data = tz->devdata;

        if (!data->ops->get_temp)
                return -EINVAL;

        return data->ops->get_temp(data->sensor_data, temp);
}

static int of_thermal_set_trips(struct thermal_zone_device *tz,
                                int low, int high)
{
        struct __thermal_zone *data = tz->devdata;

        if (!data->ops || !data->ops->set_trips)
                return -EINVAL;

        return data->ops->set_trips(data->sensor_data, low, high);
}

/**
 * of_thermal_get_ntrips - function to export number of available trip
 *                         points.
 * @tz: pointer to a thermal zone
 *
 * This function is a globally visible wrapper to get number of trip points
 * stored in the local struct __thermal_zone
 *
 * Return: number of available trip points, -ENODEV when data not available
 */
int of_thermal_get_ntrips(struct thermal_zone_device *tz)
{
        struct __thermal_zone *data = tz->devdata;

        if (!data || IS_ERR(data))
                return -ENODEV;

        return data->ntrips;
}
EXPORT_SYMBOL_GPL(of_thermal_get_ntrips);

/**
 * of_thermal_is_trip_valid - function to check if trip point is valid
 *
 * @tz: pointer to a thermal zone
 * @trip:       trip point to evaluate
 *
 * This function is responsible for checking if passed trip point is valid
 *
 * Return: true if trip point is valid, false otherwise
 */
bool of_thermal_is_trip_valid(struct thermal_zone_device *tz, int trip)
{
        struct __thermal_zone *data = tz->devdata;

        if (!data || trip >= data->ntrips || trip < 0)
                return false;

        return true;
}
EXPORT_SYMBOL_GPL(of_thermal_is_trip_valid);

/**
 * of_thermal_get_trip_points - function to get access to a globally exported
 *                              trip points
 *
 * @tz: pointer to a thermal zone
 *
 * This function provides a pointer to trip points table
 *
 * Return: pointer to trip points table, NULL otherwise
 */
const struct thermal_trip *
of_thermal_get_trip_points(struct thermal_zone_device *tz)
{
        struct __thermal_zone *data = tz->devdata;

        if (!data)
                return NULL;

        return data->trips;
}
EXPORT_SYMBOL_GPL(of_thermal_get_trip_points);

/**
 * of_thermal_set_emul_temp - function to set emulated temperature
 *
 * @tz: pointer to a thermal zone
 * @temp:       temperature to set
 *
 * This function gives the ability to set emulated value of temperature,
 * which is handy for debugging
 *
 * Return: zero on success, error code otherwise
 */
static int of_thermal_set_emul_temp(struct thermal_zone_device *tz,
                                    int temp)
{
        struct __thermal_zone *data = tz->devdata;

        return data->ops->set_emul_temp(data->sensor_data, temp);
}

static int of_thermal_get_trend(struct thermal_zone_device *tz, int trip,
                                enum thermal_trend *trend)
{
        struct __thermal_zone *data = tz->devdata;

        if (!data->ops->get_trend)
                return -EINVAL;

        return data->ops->get_trend(data->sensor_data, trip, trend);
}

static int of_thermal_bind(struct thermal_zone_device *thermal,
                           struct thermal_cooling_device *cdev)
{
        struct __thermal_zone *data = thermal->devdata;
        int i;

        if (!data || IS_ERR(data))
                return -ENODEV;

        /* find where to bind */
        for (i = 0; i < data->num_tbps; i++) {
                struct __thermal_bind_params *tbp = data->tbps + i;

                if (tbp->cooling_device == cdev->np) {
                        int ret;

                        ret = thermal_zone_bind_cooling_device(thermal,
                                                tbp->trip_id, cdev,
                                                tbp->max,
                                                tbp->min,
                                                tbp->usage);
                        if (ret)
                                return ret;
                }
        }

        return 0;
}

static int of_thermal_unbind(struct thermal_zone_device *thermal,
                             struct thermal_cooling_device *cdev)
{
        struct __thermal_zone *data = thermal->devdata;
        int i;

        if (!data || IS_ERR(data))
                return -ENODEV;

        /* find where to unbind */
        for (i = 0; i < data->num_tbps; i++) {
                struct __thermal_bind_params *tbp = data->tbps + i;

                if (tbp->cooling_device == cdev->np) {
                        int ret;

                        ret = thermal_zone_unbind_cooling_device(thermal,
                                                tbp->trip_id, cdev);
                        if (ret)
                                return ret;
                }
        }

        return 0;
}

static int of_thermal_get_mode(struct thermal_zone_device *tz,
                               enum thermal_device_mode *mode)
{
        struct __thermal_zone *data = tz->devdata;

        *mode = data->mode;

        return 0;
}

static int of_thermal_set_mode(struct thermal_zone_device *tz,
                               enum thermal_device_mode mode)
{
        struct __thermal_zone *data = tz->devdata;

        mutex_lock(&tz->lock);

        if (mode == THERMAL_DEVICE_ENABLED) {
                tz->polling_delay = data->polling_delay;
                tz->passive_delay = data->passive_delay;
        } else {
                tz->polling_delay = 0;
                tz->passive_delay = 0;
        }

        mutex_unlock(&tz->lock);

        data->mode = mode;
        thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);

        return 0;
}

static int of_thermal_get_trip_type(struct thermal_zone_device *tz, int trip,
                                    enum thermal_trip_type *type)
{
        struct __thermal_zone *data = tz->devdata;

        if (trip >= data->ntrips || trip < 0)
                return -EDOM;

        *type = data->trips[trip].type;

        return 0;
}

static int of_thermal_get_trip_temp(struct thermal_zone_device *tz, int trip,
                                    int *temp)
{
        struct __thermal_zone *data = tz->devdata;

        if (trip >= data->ntrips || trip < 0)
                return -EDOM;

        *temp = data->trips[trip].temperature;

        return 0;
}

static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
                                    int temp)
{
        struct __thermal_zone *data = tz->devdata;

        if (trip >= data->ntrips || trip < 0)
                return -EDOM;

        if (data->ops->set_trip_temp) {
                int ret;

                ret = data->ops->set_trip_temp(data->sensor_data, trip, temp);
                if (ret)
                        return ret;
        }

        /* thermal framework should take care of data->mask & (1 << trip) */
        data->trips[trip].temperature = temp;

        return 0;
}

static int of_thermal_get_trip_hyst(struct thermal_zone_device *tz, int trip,
                                    int *hyst)
{
        struct __thermal_zone *data = tz->devdata;

        if (trip >= data->ntrips || trip < 0)
                return -EDOM;

        *hyst = data->trips[trip].hysteresis;

        return 0;
}

static int of_thermal_set_trip_hyst(struct thermal_zone_device *tz, int trip,
                                    int hyst)
{
        struct __thermal_zone *data = tz->devdata;

        if (trip >= data->ntrips || trip < 0)
                return -EDOM;

        /* thermal framework should take care of data->mask & (1 << trip) */
        data->trips[trip].hysteresis = hyst;

        return 0;
}

static int of_thermal_get_crit_temp(struct thermal_zone_device *tz,
                                    int *temp)
{
        struct __thermal_zone *data = tz->devdata;
        int i;

        for (i = 0; i < data->ntrips; i++)
                if (data->trips[i].type == THERMAL_TRIP_CRITICAL) {
                        *temp = data->trips[i].temperature;
                        return 0;
                }

        return -EINVAL;
}

static struct thermal_zone_device_ops of_thermal_ops = {
        .get_mode = of_thermal_get_mode,
        .set_mode = of_thermal_set_mode,

        .get_trip_type = of_thermal_get_trip_type,
        .get_trip_temp = of_thermal_get_trip_temp,
        .set_trip_temp = of_thermal_set_trip_temp,
        .get_trip_hyst = of_thermal_get_trip_hyst,
        .set_trip_hyst = of_thermal_set_trip_hyst,
        .get_crit_temp = of_thermal_get_crit_temp,

        .bind = of_thermal_bind,
        .unbind = of_thermal_unbind,
};

/***   sensor API   ***/

static struct thermal_zone_device *
thermal_zone_of_add_sensor(struct device_node *zone,
                           struct device_node *sensor, void *data,
                           const struct thermal_zone_of_device_ops *ops)
{
        struct thermal_zone_device *tzd;
        struct __thermal_zone *tz;

        tzd = thermal_zone_get_zone_by_name(zone->name);
        if (IS_ERR(tzd))
                return ERR_PTR(-EPROBE_DEFER);

        tz = tzd->devdata;

        if (!ops)
                return ERR_PTR(-EINVAL);

        mutex_lock(&tzd->lock);
        tz->ops = ops;
        tz->sensor_data = data;

        tzd->ops->get_temp = of_thermal_get_temp;
        tzd->ops->get_trend = of_thermal_get_trend;

        /*
         * The thermal zone core will calculate the window if they have set the
         * optional set_trips pointer.
         */
        if (ops->set_trips)
                tzd->ops->set_trips = of_thermal_set_trips;

        if (ops->set_emul_temp)
                tzd->ops->set_emul_temp = of_thermal_set_emul_temp;

        mutex_unlock(&tzd->lock);

        return tzd;
}

/**
 * thermal_zone_of_sensor_register - registers a sensor to a DT thermal zone
 * @dev: a valid struct device pointer of a sensor device. Must contain
 *       a valid .of_node, for the sensor node.
 * @sensor_id: a sensor identifier, in case the sensor IP has more
 *             than one sensors
 * @data: a private pointer (owned by the caller) that will be passed
 *        back, when a temperature reading is needed.
 * @ops: struct thermal_zone_of_device_ops *. Must contain at least .get_temp.
 *
 * This function will search the list of thermal zones described in device
 * tree and look for the zone that refer to the sensor device pointed by
 * @dev->of_node as temperature providers. For the zone pointing to the
 * sensor node, the sensor will be added to the DT thermal zone device.
 *
 * The thermal zone temperature is provided by the @get_temp function
 * pointer. When called, it will have the private pointer @data back.
 *
 * The thermal zone temperature trend is provided by the @get_trend function
 * pointer. When called, it will have the private pointer @data back.
 *
 * TODO:
 * 01 - This function must enqueue the new sensor instead of using
 * it as the only source of temperature values.
 *
 * 02 - There must be a way to match the sensor with all thermal zones
 * that refer to it.
 *
 * Return: On success returns a valid struct thermal_zone_device,
 * otherwise, it returns a corresponding ERR_PTR(). Caller must
 * check the return value with help of IS_ERR() helper.
 */
struct thermal_zone_device *
thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
                                const struct thermal_zone_of_device_ops *ops)
{
        struct device_node *np, *child, *sensor_np;
        struct thermal_zone_device *tzd = ERR_PTR(-ENODEV);

        np = of_find_node_by_name(NULL, "thermal-zones");
        if (!np)
                return ERR_PTR(-ENODEV);

        if (!dev || !dev->of_node) {
                of_node_put(np);
                return ERR_PTR(-EINVAL);
        }

        sensor_np = of_node_get(dev->of_node);

        for_each_available_child_of_node(np, child) {
                struct of_phandle_args sensor_specs;
                int ret, id;

                /* For now, thermal framework supports only 1 sensor per zone */
                ret = of_parse_phandle_with_args(child, "thermal-sensors",
                                                 "#thermal-sensor-cells",
                                                 0, &sensor_specs);
                if (ret)
                        continue;

                if (sensor_specs.args_count >= 1) {
                        id = sensor_specs.args[0];
                        WARN(sensor_specs.args_count > 1,
                             "%s: too many cells in sensor specifier %d\n",
                             sensor_specs.np->name, sensor_specs.args_count);
                } else {
                        id = 0;
                }

                if (sensor_specs.np == sensor_np && id == sensor_id) {
                        tzd = thermal_zone_of_add_sensor(child, sensor_np,
                                                         data, ops);
                        if (!IS_ERR(tzd))
                                tzd->ops->set_mode(tzd, THERMAL_DEVICE_ENABLED);

                        of_node_put(sensor_specs.np);
                        of_node_put(child);
                        goto exit;
                }
                of_node_put(sensor_specs.np);
        }
exit:
        of_node_put(sensor_np);
        of_node_put(np);

        return tzd;
}
EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_register);

/**
 * thermal_zone_of_sensor_unregister - unregisters a sensor from a DT thermal zone
 * @dev: a valid struct device pointer of a sensor device. Must contain
 *       a valid .of_node, for the sensor node.
 * @tzd: a pointer to struct thermal_zone_device where the sensor is registered.
 *
 * This function removes the sensor callbacks and private data from the
 * thermal zone device registered with thermal_zone_of_sensor_register()
 * API. It will also silent the zone by remove the .get_temp() and .get_trend()
 * thermal zone device callbacks.
 *
 * TODO: When the support to several sensors per zone is added, this
 * function must search the sensor list based on @dev parameter.
 *
 */
void thermal_zone_of_sensor_unregister(struct device *dev,
                                       struct thermal_zone_device *tzd)
{
        struct __thermal_zone *tz;

        if (!dev || !tzd || !tzd->devdata)
                return;

        tz = tzd->devdata;

        /* no __thermal_zone, nothing to be done */
        if (!tz)
                return;

        mutex_lock(&tzd->lock);
        tzd->ops->get_temp = NULL;
        tzd->ops->get_trend = NULL;
        tzd->ops->set_emul_temp = NULL;

        tz->ops = NULL;
        tz->sensor_data = NULL;
        mutex_unlock(&tzd->lock);
}
EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_unregister);

static void devm_thermal_zone_of_sensor_release(struct device *dev, void *res)
{
        thermal_zone_of_sensor_unregister(dev,
                                          *(struct thermal_zone_device **)res);
}

static int devm_thermal_zone_of_sensor_match(struct device *dev, void *res,
                                             void *data)
{
        struct thermal_zone_device **r = res;

        if (WARN_ON(!r || !*r))
                return 0;

        return *r == data;
}

/**
 * devm_thermal_zone_of_sensor_register - Resource managed version of
 *                              thermal_zone_of_sensor_register()
 * @dev: a valid struct device pointer of a sensor device. Must contain
 *       a valid .of_node, for the sensor node.
 * @sensor_id: a sensor identifier, in case the sensor IP has more
 *             than one sensors
 * @data: a private pointer (owned by the caller) that will be passed
 *        back, when a temperature reading is needed.
 * @ops: struct thermal_zone_of_device_ops *. Must contain at least .get_temp.
 *
 * Refer thermal_zone_of_sensor_register() for more details.
 *
 * Return: On success returns a valid struct thermal_zone_device,
 * otherwise, it returns a corresponding ERR_PTR(). Caller must
 * check the return value with help of IS_ERR() helper.
 * Registered thermal_zone_device device will automatically be
 * released when device is unbounded.
 */
struct thermal_zone_device *devm_thermal_zone_of_sensor_register(
        struct device *dev, int sensor_id,
        void *data, const struct thermal_zone_of_device_ops *ops)
{
        struct thermal_zone_device **ptr, *tzd;

        ptr = devres_alloc(devm_thermal_zone_of_sensor_release, sizeof(*ptr),
                           GFP_KERNEL);
        if (!ptr)
                return ERR_PTR(-ENOMEM);

        tzd = thermal_zone_of_sensor_register(dev, sensor_id, data, ops);
        if (IS_ERR(tzd)) {
                devres_free(ptr);
                return tzd;
        }

        *ptr = tzd;
        devres_add(dev, ptr);

        return tzd;
}
EXPORT_SYMBOL_GPL(devm_thermal_zone_of_sensor_register);

/**
 * devm_thermal_zone_of_sensor_unregister - Resource managed version of
 *                              thermal_zone_of_sensor_unregister().
 * @dev: Device for which which resource was allocated.
 * @tzd: a pointer to struct thermal_zone_device where the sensor is registered.
 *
 * This function removes the sensor callbacks and private data from the
 * thermal zone device registered with devm_thermal_zone_of_sensor_register()
 * API. It will also silent the zone by remove the .get_temp() and .get_trend()
 * thermal zone device callbacks.
 * Normally this function will not need to be called and the resource
 * management code will ensure that the resource is freed.
 */
void devm_thermal_zone_of_sensor_unregister(struct device *dev,
                                            struct thermal_zone_device *tzd)
{
        WARN_ON(devres_release(dev, devm_thermal_zone_of_sensor_release,
                               devm_thermal_zone_of_sensor_match, tzd));
}
EXPORT_SYMBOL_GPL(devm_thermal_zone_of_sensor_unregister);

/***   functions parsing device tree nodes   ***/

/**
 * thermal_of_populate_bind_params - parse and fill cooling map data
 * @np: DT node containing a cooling-map node
 * @__tbp: data structure to be filled with cooling map info
 * @trips: array of thermal zone trip points
 * @ntrips: number of trip points inside trips.
 *
 * This function parses a cooling-map type of node represented by
 * @np parameter and fills the read data into @__tbp data structure.
 * It needs the already parsed array of trip points of the thermal zone
 * in consideration.
 *
 * Return: 0 on success, proper error code otherwise
 */
static int thermal_of_populate_bind_params(struct device_node *np,
                                           struct __thermal_bind_params *__tbp,
                                           struct thermal_trip *trips,
                                           int ntrips)
{
        struct of_phandle_args cooling_spec;
        struct device_node *trip;
        int ret, i;
        u32 prop;

        /* Default weight. Usage is optional */
        __tbp->usage = THERMAL_WEIGHT_DEFAULT;
        ret = of_property_read_u32(np, "contribution", &prop);
        if (ret == 0)
                __tbp->usage = prop;

        trip = of_parse_phandle(np, "trip", 0);
        if (!trip) {
                pr_err("missing trip property\n");
                return -ENODEV;
        }

        /* match using device_node */
        for (i = 0; i < ntrips; i++)
                if (trip == trips[i].np) {
                        __tbp->trip_id = i;
                        break;
                }

        if (i == ntrips) {
                ret = -ENODEV;
                goto end;
        }

        ret = of_parse_phandle_with_args(np, "cooling-device", "#cooling-cells",
                                         0, &cooling_spec);
        if (ret < 0) {
                pr_err("missing cooling_device property\n");
                goto end;
        }
        __tbp->cooling_device = cooling_spec.np;
        if (cooling_spec.args_count >= 2) { /* at least min and max */
                __tbp->min = cooling_spec.args[0];
                __tbp->max = cooling_spec.args[1];
        } else {
                pr_err("wrong reference to cooling device, missing limits\n");
        }

end:
        of_node_put(trip);

        return ret;
}

/**
 * It maps 'enum thermal_trip_type' found in include/linux/thermal.h
 * into the device tree binding of 'trip', property type.
 */
static const char * const trip_types[] = {
        [THERMAL_TRIP_ACTIVE]   = "active",
        [THERMAL_TRIP_PASSIVE]  = "passive",
        [THERMAL_TRIP_HOT]      = "hot",
        [THERMAL_TRIP_CRITICAL] = "critical",
};

/**
 * thermal_of_get_trip_type - Get phy mode for given device_node
 * @np: Pointer to the given device_node
 * @type: Pointer to resulting trip type
 *
 * The function gets trip type string from property 'type',
 * and store its index in trip_types table in @type,
 *
 * Return: 0 on success, or errno in error case.
 */
static int thermal_of_get_trip_type(struct device_node *np,
                                    enum thermal_trip_type *type)
{
        const char *t;
        int err, i;

        err = of_property_read_string(np, "type", &t);
        if (err < 0)
                return err;

        for (i = 0; i < ARRAY_SIZE(trip_types); i++)
                if (!strcasecmp(t, trip_types[i])) {
                        *type = i;
                        return 0;
                }

        return -ENODEV;
}

/**
 * thermal_of_populate_trip - parse and fill one trip point data
 * @np: DT node containing a trip point node
 * @trip: trip point data structure to be filled up
 *
 * This function parses a trip point type of node represented by
 * @np parameter and fills the read data into @trip data structure.
 *
 * Return: 0 on success, proper error code otherwise
 */
static int thermal_of_populate_trip(struct device_node *np,
                                    struct thermal_trip *trip)
{
        int prop;
        int ret;

        ret = of_property_read_u32(np, "temperature", &prop);
        if (ret < 0) {
                pr_err("missing temperature property\n");
                return ret;
        }
        trip->temperature = prop;

        ret = of_property_read_u32(np, "hysteresis", &prop);
        if (ret < 0) {
                pr_err("missing hysteresis property\n");
                return ret;
        }
        trip->hysteresis = prop;

        ret = thermal_of_get_trip_type(np, &trip->type);
        if (ret < 0) {
                pr_err("wrong trip type property\n");
                return ret;
        }

        /* Required for cooling map matching */
        trip->np = np;
        of_node_get(np);

        return 0;
}

/**
 * thermal_of_build_thermal_zone - parse and fill one thermal zone data
 * @np: DT node containing a thermal zone node
 *
 * This function parses a thermal zone type of node represented by
 * @np parameter and fills the read data into a __thermal_zone data structure
 * and return this pointer.
 *
 * TODO: Missing properties to parse: thermal-sensor-names
 *
 * Return: On success returns a valid struct __thermal_zone,
 * otherwise, it returns a corresponding ERR_PTR(). Caller must
 * check the return value with help of IS_ERR() helper.
 */
static struct __thermal_zone
__init *thermal_of_build_thermal_zone(struct device_node *np)
{
        struct device_node *child = NULL, *gchild;
        struct __thermal_zone *tz;
        int ret, i;
        u32 prop, coef[2];

        if (!np) {
                pr_err("no thermal zone np\n");
                return ERR_PTR(-EINVAL);
        }

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

        ret = of_property_read_u32(np, "polling-delay-passive", &prop);
        if (ret < 0) {
                pr_err("missing polling-delay-passive property\n");
                goto free_tz;
        }
        tz->passive_delay = prop;

        ret = of_property_read_u32(np, "polling-delay", &prop);
        if (ret < 0) {
                pr_err("missing polling-delay property\n");
                goto free_tz;
        }
        tz->polling_delay = prop;

        /*
         * REVIST: for now, the thermal framework supports only
         * one sensor per thermal zone. Thus, we are considering
         * only the first two values as slope and offset.
         */
        ret = of_property_read_u32_array(np, "coefficients", coef, 2);
        if (ret == 0) {
                tz->slope = coef[0];
                tz->offset = coef[1];
        } else {
                tz->slope = 1;
                tz->offset = 0;
        }

        /* trips */
        child = of_get_child_by_name(np, "trips");

        /* No trips provided */
        if (!child)
                goto finish;

        tz->ntrips = of_get_child_count(child);
        if (tz->ntrips == 0) /* must have at least one child */
                goto finish;

        tz->trips = kcalloc(tz->ntrips, sizeof(*tz->trips), GFP_KERNEL);
        if (!tz->trips) {
                ret = -ENOMEM;
                goto free_tz;
        }

        i = 0;
        for_each_child_of_node(child, gchild) {
                ret = thermal_of_populate_trip(gchild, &tz->trips[i++]);
                if (ret)
                        goto free_trips;
        }

        of_node_put(child);

        /* cooling-maps */
        child = of_get_child_by_name(np, "cooling-maps");

        /* cooling-maps not provided */
        if (!child)
                goto finish;

        tz->num_tbps = of_get_child_count(child);
        if (tz->num_tbps == 0)
                goto finish;

        tz->tbps = kcalloc(tz->num_tbps, sizeof(*tz->tbps), GFP_KERNEL);
        if (!tz->tbps) {
                ret = -ENOMEM;
                goto free_trips;
        }

        i = 0;
        for_each_child_of_node(child, gchild) {
                ret = thermal_of_populate_bind_params(gchild, &tz->tbps[i++],
                                                      tz->trips, tz->ntrips);
                if (ret)
                        goto free_tbps;
        }

finish:
        of_node_put(child);
        tz->mode = THERMAL_DEVICE_DISABLED;

        return tz;

free_tbps:
        for (i = i - 1; i >= 0; i--)
                of_node_put(tz->tbps[i].cooling_device);
        kfree(tz->tbps);
free_trips:
        for (i = 0; i < tz->ntrips; i++)
                of_node_put(tz->trips[i].np);
        kfree(tz->trips);
        of_node_put(gchild);
free_tz:
        kfree(tz);
        of_node_put(child);

        return ERR_PTR(ret);
}

static inline void of_thermal_free_zone(struct __thermal_zone *tz)
{
        int i;

        for (i = 0; i < tz->num_tbps; i++)
                of_node_put(tz->tbps[i].cooling_device);
        kfree(tz->tbps);
        for (i = 0; i < tz->ntrips; i++)
                of_node_put(tz->trips[i].np);
        kfree(tz->trips);
        kfree(tz);
}

/**
 * of_parse_thermal_zones - parse device tree thermal data
 *
 * Initialization function that can be called by machine initialization
 * code to parse thermal data and populate the thermal framework
 * with hardware thermal zones info. This function only parses thermal zones.
 * Cooling devices and sensor devices nodes are supposed to be parsed
 * by their respective drivers.
 *
 * Return: 0 on success, proper error code otherwise
 *
 */
int __init of_parse_thermal_zones(void)
{
        struct device_node *np, *child;
        struct __thermal_zone *tz;
        struct thermal_zone_device_ops *ops;

        np = of_find_node_by_name(NULL, "thermal-zones");
        if (!np) {
                pr_debug("unable to find thermal zones\n");
                return 0; /* Run successfully on systems without thermal DT */
        }

        for_each_available_child_of_node(np, child) {
                struct thermal_zone_device *zone;
                struct thermal_zone_params *tzp;
                int i, mask = 0;
                u32 prop;

                tz = thermal_of_build_thermal_zone(child);
                if (IS_ERR(tz)) {
                        pr_err("failed to build thermal zone %s: %ld\n",
                               child->name,
                               PTR_ERR(tz));
                        continue;
                }

                ops = kmemdup(&of_thermal_ops, sizeof(*ops), GFP_KERNEL);
                if (!ops)
                        goto exit_free;

                tzp = kzalloc(sizeof(*tzp), GFP_KERNEL);
                if (!tzp) {
                        kfree(ops);
                        goto exit_free;
                }

                /* No hwmon because there might be hwmon drivers registering */
                tzp->no_hwmon = true;

                if (!of_property_read_u32(child, "sustainable-power", &prop))
                        tzp->sustainable_power = prop;

                for (i = 0; i < tz->ntrips; i++)
                        mask |= 1 << i;

                /* these two are left for temperature drivers to use */
                tzp->slope = tz->slope;
                tzp->offset = tz->offset;

                zone = thermal_zone_device_register(child->name, tz->ntrips,
                                                    mask, tz,
                                                    ops, tzp,
                                                    tz->passive_delay,
                                                    tz->polling_delay);
                if (IS_ERR(zone)) {
                        pr_err("Failed to build %s zone %ld\n", child->name,
                               PTR_ERR(zone));
                        kfree(tzp);
                        kfree(ops);
                        of_thermal_free_zone(tz);
                        /* attempting to build remaining zones still */
                }
        }
        of_node_put(np);

        return 0;

exit_free:
        of_node_put(child);
        of_node_put(np);
        of_thermal_free_zone(tz);

        /* no memory available, so free what we have built */
        of_thermal_destroy_zones();

        return -ENOMEM;
}

/**
 * of_thermal_destroy_zones - remove all zones parsed and allocated resources
 *
 * Finds all zones parsed and added to the thermal framework and remove them
 * from the system, together with their resources.
 *
 */
void of_thermal_destroy_zones(void)
{
        struct device_node *np, *child;

        np = of_find_node_by_name(NULL, "thermal-zones");
        if (!np) {
                pr_debug("unable to find thermal zones\n");
                return;
        }

        for_each_available_child_of_node(np, child) {
                struct thermal_zone_device *zone;

                zone = thermal_zone_get_zone_by_name(child->name);
                if (IS_ERR(zone))
                        continue;

                thermal_zone_device_unregister(zone);
                kfree(zone->tzp);
                kfree(zone->ops);
                of_thermal_free_zone(zone->devdata);
        }
        of_node_put(np);
}