/*
   * Copyright © 2007 Anton Vorontsov <cbou@mail.ru>
   * Copyright © 2007 Eugeny Boger <eugenyboger@dgap.mipt.ru>
   *
   * Author: Eugeny Boger <eugenyboger@dgap.mipt.ru>
   *
   * Use consistent with the GNU GPL is permitted,
   * provided that this copyright notice is
   * preserved in its entirety in all copies and derived works.
   */
  
  #include <linux/module.h>
  #include <linux/power_supply.h>
  #include <linux/apm-emulation.h>

  #define PSY_PROP(psy, prop, val) (psy->get_property(psy, \
  			 POWER_SUPPLY_PROP_##prop, val))

  #define _MPSY_PROP(prop, val) (main_battery->get_property(main_battery, \
  							 prop, val))

  
  #define MPSY_PROP(prop, val) _MPSY_PROP(POWER_SUPPLY_PROP_##prop, val)

  static DEFINE_MUTEX(apm_mutex);

  static struct power_supply *main_battery;

  enum apm_source {
  	SOURCE_ENERGY,
  	SOURCE_CHARGE,
  	SOURCE_VOLTAGE,
  };

  struct find_bat_param {
  	struct power_supply *main;
  	struct power_supply *bat;
  	struct power_supply *max_charge_bat;
  	struct power_supply *max_energy_bat;

  	union power_supply_propval full;

  	int max_charge;
  	int max_energy;
  };

  static int __find_main_battery(struct device *dev, void *data)
  {
  	struct find_bat_param *bp = (struct find_bat_param *)data;

  	bp->bat = dev_get_drvdata(dev);

  	if (bp->bat->use_for_apm) {
  		/* nice, we explicitly asked to report this battery. */
  		bp->main = bp->bat;
  		return 1;
  	}

  	if (!PSY_PROP(bp->bat, CHARGE_FULL_DESIGN, &bp->full) ||
  			!PSY_PROP(bp->bat, CHARGE_FULL, &bp->full)) {
  		if (bp->full.intval > bp->max_charge) {
  			bp->max_charge_bat = bp->bat;
  			bp->max_charge = bp->full.intval;
  		}
  	} else if (!PSY_PROP(bp->bat, ENERGY_FULL_DESIGN, &bp->full) ||
  			!PSY_PROP(bp->bat, ENERGY_FULL, &bp->full)) {
  		if (bp->full.intval > bp->max_energy) {
  			bp->max_energy_bat = bp->bat;
  			bp->max_energy = bp->full.intval;

  		}

  	}

  	return 0;
  }
  
  static void find_main_battery(void)
  {
  	struct find_bat_param bp;
  	int error;
  
  	memset(&bp, 0, sizeof(struct find_bat_param));
  	main_battery = NULL;
  	bp.main = main_battery;

  	error = class_for_each_device(power_supply_class, NULL, &bp,

  				      __find_main_battery);
  	if (error) {
  		main_battery = bp.main;
  		return;
  	}

  	if ((bp.max_energy_bat && bp.max_charge_bat) &&
  			(bp.max_energy_bat != bp.max_charge_bat)) {

  		/* try guess battery with more capacity */

  		if (!PSY_PROP(bp.max_charge_bat, VOLTAGE_MAX_DESIGN,
  			      &bp.full)) {
  			if (bp.max_energy > bp.max_charge * bp.full.intval)
  				main_battery = bp.max_energy_bat;

  			else

  				main_battery = bp.max_charge_bat;
  		} else if (!PSY_PROP(bp.max_energy_bat, VOLTAGE_MAX_DESIGN,
  								  &bp.full)) {
  			if (bp.max_charge > bp.max_energy / bp.full.intval)
  				main_battery = bp.max_charge_bat;

  			else

  				main_battery = bp.max_energy_bat;

  		} else {
  			/* give up, choice any */

  			main_battery = bp.max_energy_bat;

  		}

  	} else if (bp.max_charge_bat) {
  		main_battery = bp.max_charge_bat;
  	} else if (bp.max_energy_bat) {
  		main_battery = bp.max_energy_bat;

  	} else {
  		/* give up, try the last if any */

  		main_battery = bp.bat;

  	}

  }

  static int do_calculate_time(int status, enum apm_source source)

  {

  	union power_supply_propval full;
  	union power_supply_propval empty;
  	union power_supply_propval cur;
  	union power_supply_propval I;
  	enum power_supply_property full_prop;
  	enum power_supply_property full_design_prop;
  	enum power_supply_property empty_prop;
  	enum power_supply_property empty_design_prop;
  	enum power_supply_property cur_avg_prop;
  	enum power_supply_property cur_now_prop;

  	if (MPSY_PROP(CURRENT_AVG, &I)) {
  		/* if battery can't report average value, use momentary */
  		if (MPSY_PROP(CURRENT_NOW, &I))

  			return -1;
  	}

  	if (!I.intval)
  		return 0;

  	switch (source) {
  	case SOURCE_CHARGE:

  		full_prop = POWER_SUPPLY_PROP_CHARGE_FULL;
  		full_design_prop = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
  		empty_prop = POWER_SUPPLY_PROP_CHARGE_EMPTY;
  		empty_design_prop = POWER_SUPPLY_PROP_CHARGE_EMPTY;
  		cur_avg_prop = POWER_SUPPLY_PROP_CHARGE_AVG;
  		cur_now_prop = POWER_SUPPLY_PROP_CHARGE_NOW;

  		break;
  	case SOURCE_ENERGY:

  		full_prop = POWER_SUPPLY_PROP_ENERGY_FULL;
  		full_design_prop = POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN;
  		empty_prop = POWER_SUPPLY_PROP_ENERGY_EMPTY;
  		empty_design_prop = POWER_SUPPLY_PROP_CHARGE_EMPTY;
  		cur_avg_prop = POWER_SUPPLY_PROP_ENERGY_AVG;
  		cur_now_prop = POWER_SUPPLY_PROP_ENERGY_NOW;

  		break;
  	case SOURCE_VOLTAGE:
  		full_prop = POWER_SUPPLY_PROP_VOLTAGE_MAX;
  		full_design_prop = POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN;
  		empty_prop = POWER_SUPPLY_PROP_VOLTAGE_MIN;
  		empty_design_prop = POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN;
  		cur_avg_prop = POWER_SUPPLY_PROP_VOLTAGE_AVG;
  		cur_now_prop = POWER_SUPPLY_PROP_VOLTAGE_NOW;
  		break;
  	default:
  		printk(KERN_ERR "Unsupported source: %d
  ", source);
  		return -1;

  	}

  	if (_MPSY_PROP(full_prop, &full)) {
  		/* if battery can't report this property, use design value */
  		if (_MPSY_PROP(full_design_prop, &full))

  			return -1;
  	}

  	if (_MPSY_PROP(empty_prop, &empty)) {
  		/* if battery can't report this property, use design value */
  		if (_MPSY_PROP(empty_design_prop, &empty))
  			empty.intval = 0;
  	}
  
  	if (_MPSY_PROP(cur_avg_prop, &cur)) {

  		/* if battery can't report average value, use momentary */

  		if (_MPSY_PROP(cur_now_prop, &cur))

  			return -1;
  	}
  
  	if (status == POWER_SUPPLY_STATUS_CHARGING)

  		return ((cur.intval - full.intval) * 60L) / I.intval;

  	else

  		return -((cur.intval - empty.intval) * 60L) / I.intval;

  }

  static int calculate_time(int status)
  {
  	int time;
  
  	time = do_calculate_time(status, SOURCE_ENERGY);
  	if (time != -1)
  		return time;
  
  	time = do_calculate_time(status, SOURCE_CHARGE);
  	if (time != -1)
  		return time;
  
  	time = do_calculate_time(status, SOURCE_VOLTAGE);
  	if (time != -1)
  		return time;
  
  	return -1;
  }
  
  static int calculate_capacity(enum apm_source source)

  {
  	enum power_supply_property full_prop, empty_prop;
  	enum power_supply_property full_design_prop, empty_design_prop;
  	enum power_supply_property now_prop, avg_prop;
  	union power_supply_propval empty, full, cur;
  	int ret;

  	switch (source) {
  	case SOURCE_CHARGE:

  		full_prop = POWER_SUPPLY_PROP_CHARGE_FULL;
  		empty_prop = POWER_SUPPLY_PROP_CHARGE_EMPTY;
  		full_design_prop = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
  		empty_design_prop = POWER_SUPPLY_PROP_CHARGE_EMPTY_DESIGN;
  		now_prop = POWER_SUPPLY_PROP_CHARGE_NOW;
  		avg_prop = POWER_SUPPLY_PROP_CHARGE_AVG;

  		break;
  	case SOURCE_ENERGY:

  		full_prop = POWER_SUPPLY_PROP_ENERGY_FULL;
  		empty_prop = POWER_SUPPLY_PROP_ENERGY_EMPTY;
  		full_design_prop = POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN;
  		empty_design_prop = POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN;
  		now_prop = POWER_SUPPLY_PROP_ENERGY_NOW;
  		avg_prop = POWER_SUPPLY_PROP_ENERGY_AVG;

  		break;

  	case SOURCE_VOLTAGE:
  		full_prop = POWER_SUPPLY_PROP_VOLTAGE_MAX;
  		empty_prop = POWER_SUPPLY_PROP_VOLTAGE_MIN;
  		full_design_prop = POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN;
  		empty_design_prop = POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN;
  		now_prop = POWER_SUPPLY_PROP_VOLTAGE_NOW;
  		avg_prop = POWER_SUPPLY_PROP_VOLTAGE_AVG;
  		break;
  	default:
  		printk(KERN_ERR "Unsupported source: %d
  ", source);
  		return -1;

  	}
  
  	if (_MPSY_PROP(full_prop, &full)) {
  		/* if battery can't report this property, use design value */
  		if (_MPSY_PROP(full_design_prop, &full))
  			return -1;
  	}
  
  	if (_MPSY_PROP(avg_prop, &cur)) {
  		/* if battery can't report average value, use momentary */
  		if (_MPSY_PROP(now_prop, &cur))
  			return -1;
  	}
  
  	if (_MPSY_PROP(empty_prop, &empty)) {
  		/* if battery can't report this property, use design value */
  		if (_MPSY_PROP(empty_design_prop, &empty))
  			empty.intval = 0;
  	}
  
  	if (full.intval - empty.intval)
  		ret =  ((cur.intval - empty.intval) * 100L) /
  		       (full.intval - empty.intval);
  	else
  		return -1;
  
  	if (ret > 100)
  		return 100;
  	else if (ret < 0)
  		return 0;
  
  	return ret;
  }
  
  static void apm_battery_apm_get_power_status(struct apm_power_info *info)
  {
  	union power_supply_propval status;
  	union power_supply_propval capacity, time_to_full, time_to_empty;

  	mutex_lock(&apm_mutex);

  	find_main_battery();
  	if (!main_battery) {

  		mutex_unlock(&apm_mutex);

  		return;
  	}
  
  	/* status */
  
  	if (MPSY_PROP(STATUS, &status))
  		status.intval = POWER_SUPPLY_STATUS_UNKNOWN;
  
  	/* ac line status */
  
  	if ((status.intval == POWER_SUPPLY_STATUS_CHARGING) ||
  	    (status.intval == POWER_SUPPLY_STATUS_NOT_CHARGING) ||
  	    (status.intval == POWER_SUPPLY_STATUS_FULL))
  		info->ac_line_status = APM_AC_ONLINE;
  	else
  		info->ac_line_status = APM_AC_OFFLINE;
  
  	/* battery life (i.e. capacity, in percents) */
  
  	if (MPSY_PROP(CAPACITY, &capacity) == 0) {
  		info->battery_life = capacity.intval;
  	} else {
  		/* try calculate using energy */

  		info->battery_life = calculate_capacity(SOURCE_ENERGY);

  		/* if failed try calculate using charge instead */
  		if (info->battery_life == -1)

  			info->battery_life = calculate_capacity(SOURCE_CHARGE);
  		if (info->battery_life == -1)
  			info->battery_life = calculate_capacity(SOURCE_VOLTAGE);

  	}
  
  	/* charging status */
  
  	if (status.intval == POWER_SUPPLY_STATUS_CHARGING) {
  		info->battery_status = APM_BATTERY_STATUS_CHARGING;
  	} else {
  		if (info->battery_life > 50)
  			info->battery_status = APM_BATTERY_STATUS_HIGH;
  		else if (info->battery_life > 5)
  			info->battery_status = APM_BATTERY_STATUS_LOW;
  		else
  			info->battery_status = APM_BATTERY_STATUS_CRITICAL;
  	}
  	info->battery_flag = info->battery_status;
  
  	/* time */
  
  	info->units = APM_UNITS_MINS;
  
  	if (status.intval == POWER_SUPPLY_STATUS_CHARGING) {

  		if (!MPSY_PROP(TIME_TO_FULL_AVG, &time_to_full) ||

  				!MPSY_PROP(TIME_TO_FULL_NOW, &time_to_full))

  			info->time = time_to_full.intval / 60;

  		else
  			info->time = calculate_time(status.intval);

  	} else {

  		if (!MPSY_PROP(TIME_TO_EMPTY_AVG, &time_to_empty) ||

  			      !MPSY_PROP(TIME_TO_EMPTY_NOW, &time_to_empty))

  			info->time = time_to_empty.intval / 60;

  		else
  			info->time = calculate_time(status.intval);

  	}

  	mutex_unlock(&apm_mutex);

  }
  
  static int __init apm_battery_init(void)
  {
  	printk(KERN_INFO "APM Battery Driver
  ");
  
  	apm_get_power_status = apm_battery_apm_get_power_status;
  	return 0;
  }
  
  static void __exit apm_battery_exit(void)
  {
  	apm_get_power_status = NULL;

  }
  
  module_init(apm_battery_init);
  module_exit(apm_battery_exit);
  
  MODULE_AUTHOR("Eugeny Boger <eugenyboger@dgap.mipt.ru>");
  MODULE_DESCRIPTION("APM emulation driver for battery monitoring class");
  MODULE_LICENSE("GPL");