/*
   *  of-thermal.c - Generic Thermal Management device tree support.
   *
   *  Copyright (C) 2013 Texas Instruments
   *  Copyright (C) 2013 Eduardo Valentin <eduardo.valentin@ti.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.
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   */
  #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 <linux/thermal.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
  ",
  			     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
  ");
  		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
  ");
  		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
  ");
  	}
  
  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
  ");
  		return ret;
  	}
  	trip->temperature = prop;
  
  	ret = of_property_read_u32(np, "hysteresis", &prop);
  	if (ret < 0) {
  		pr_err("missing hysteresis property
  ");
  		return ret;
  	}
  	trip->hysteresis = prop;
  
  	ret = thermal_of_get_trip_type(np, &trip->type);
  	if (ret < 0) {
  		pr_err("wrong trip type property
  ");
  		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
  ");
  		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
  ");
  		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
  ");
  		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 = kzalloc(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 = kzalloc(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
  ");
  		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
  ",
  			       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
  ", 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
  ");

  		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);

  }