drivers/power/ds2760_battery.c - kernel/msm-4.9 - Gitiles

 /*
  * Driver for batteries with DS2760 chips inside.
  *
  * Copyright © 2007 Anton Vorontsov
  *	       2004-2007 Matt Reimer
  *	       2004 Szabolcs Gyurko
  *
  * Use consistent with the GNU GPL is permitted,
  * provided that this copyright notice is
  * preserved in its entirety in all copies and derived works.
  *
  * Author:  Anton Vorontsov <cbou@mail.ru>
  *	    February 2007
  *
  *	    Matt Reimer <mreimer@vpop.net>
  *	    April 2004, 2005, 2007
  *
  *	    Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
  *	    September 2004
  */

 #include <linux/module.h>
 #include <linux/param.h>
 #include <linux/jiffies.h>
 #include <linux/workqueue.h>
 #include <linux/pm.h>
 #include <linux/platform_device.h>
 #include <linux/power_supply.h>

 #include "../w1/w1.h"
 #include "../w1/slaves/w1_ds2760.h"

 struct ds2760_device_info {
 	struct device *dev;

 	/* DS2760 data, valid after calling ds2760_battery_read_status() */
 	unsigned long update_time;	/* jiffies when data read */
 	char raw[DS2760_DATA_SIZE];	/* raw DS2760 data */
 	int voltage_raw;		/* units of 4.88 mV */
 	int voltage_uV;			/* units of µV */
 	int current_raw;		/* units of 0.625 mA */
 	int current_uA;			/* units of µA */
 	int accum_current_raw;		/* units of 0.25 mAh */
 	int accum_current_uAh;		/* units of µAh */
 	int temp_raw;			/* units of 0.125 °C */
 	int temp_C;			/* units of 0.1 °C */
 	int rated_capacity;		/* units of µAh */
 	int rem_capacity;		/* percentage */
 	int full_active_uAh;		/* units of µAh */
 	int empty_uAh;			/* units of µAh */
 	int life_sec;			/* units of seconds */
 	int charge_status;		/* POWER_SUPPLY_STATUS_* */

 	int full_counter;
 	struct power_supply bat;
 	struct device *w1_dev;
 	struct workqueue_struct *monitor_wqueue;
 	struct delayed_work monitor_work;
 	struct delayed_work set_charged_work;
 };

 static unsigned int cache_time = 1000;
 module_param(cache_time, uint, 0644);
 MODULE_PARM_DESC(cache_time, "cache time in milliseconds");

 static unsigned int pmod_enabled;
 module_param(pmod_enabled, bool, 0644);
 MODULE_PARM_DESC(pmod_enabled, "PMOD enable bit");

 static unsigned int rated_capacity;
 module_param(rated_capacity, uint, 0644);
 MODULE_PARM_DESC(rated_capacity, "rated battery capacity, 10*mAh or index");

 static unsigned int current_accum;
 module_param(current_accum, uint, 0644);
 MODULE_PARM_DESC(current_accum, "current accumulator value");

 /* Some batteries have their rated capacity stored a N * 10 mAh, while
  * others use an index into this table. */
 static int rated_capacities[] = {
 	0,
 	920,	/* Samsung */
 	920,	/* BYD */
 	920,	/* Lishen */
 	920,	/* NEC */
 	1440,	/* Samsung */
 	1440,	/* BYD */
 	1440,	/* Lishen */
 	1440,	/* NEC */
 	2880,	/* Samsung */
 	2880,	/* BYD */
 	2880,	/* Lishen */
 	2880	/* NEC */
 };

 /* array is level at temps 0°C, 10°C, 20°C, 30°C, 40°C
  * temp is in Celsius */
 static int battery_interpolate(int array[], int temp)
 {
 	int index, dt;

 	if (temp <= 0)
 		return array[0];
 	if (temp >= 40)
 		return array[4];

 	index = temp / 10;
 	dt    = temp % 10;

 	return array[index] + (((array[index + 1] - array[index]) * dt) / 10);
 }

 static int ds2760_battery_read_status(struct ds2760_device_info *di)
 {
 	int ret, i, start, count, scale[5];

 	if (di->update_time && time_before(jiffies, di->update_time +
 					   msecs_to_jiffies(cache_time)))
 		return 0;

 	/* The first time we read the entire contents of SRAM/EEPROM,
 	 * but after that we just read the interesting bits that change. */
 	if (di->update_time == 0) {
 		start = 0;
 		count = DS2760_DATA_SIZE;
 	} else {
 		start = DS2760_VOLTAGE_MSB;
 		count = DS2760_TEMP_LSB - start + 1;
 	}

 	ret = w1_ds2760_read(di->w1_dev, di->raw + start, start, count);
 	if (ret != count) {
 		dev_warn(di->dev, "call to w1_ds2760_read failed (0x%p)\n",
 			 di->w1_dev);
 		return 1;
 	}

 	di->update_time = jiffies;

 	/* DS2760 reports voltage in units of 4.88mV, but the battery class
 	 * reports in units of uV, so convert by multiplying by 4880. */
 	di->voltage_raw = (di->raw[DS2760_VOLTAGE_MSB] << 3) |
 			  (di->raw[DS2760_VOLTAGE_LSB] >> 5);
 	di->voltage_uV = di->voltage_raw * 4880;

 	/* DS2760 reports current in signed units of 0.625mA, but the battery
 	 * class reports in units of µA, so convert by multiplying by 625. */
 	di->current_raw =
 	    (((signed char)di->raw[DS2760_CURRENT_MSB]) << 5) |
 			  (di->raw[DS2760_CURRENT_LSB] >> 3);
 	di->current_uA = di->current_raw * 625;

 	/* DS2760 reports accumulated current in signed units of 0.25mAh. */
 	di->accum_current_raw =
 	    (((signed char)di->raw[DS2760_CURRENT_ACCUM_MSB]) << 8) |
 			   di->raw[DS2760_CURRENT_ACCUM_LSB];
 	di->accum_current_uAh = di->accum_current_raw * 250;

 	/* DS2760 reports temperature in signed units of 0.125°C, but the
 	 * battery class reports in units of 1/10 °C, so we convert by
 	 * multiplying by .125 * 10 = 1.25. */
 	di->temp_raw = (((signed char)di->raw[DS2760_TEMP_MSB]) << 3) |
 				     (di->raw[DS2760_TEMP_LSB] >> 5);
 	di->temp_C = di->temp_raw + (di->temp_raw / 4);

 	/* At least some battery monitors (e.g. HP iPAQ) store the battery's
 	 * maximum rated capacity. */
 	if (di->raw[DS2760_RATED_CAPACITY] < ARRAY_SIZE(rated_capacities))
 		di->rated_capacity = rated_capacities[
 			(unsigned int)di->raw[DS2760_RATED_CAPACITY]];
 	else
 		di->rated_capacity = di->raw[DS2760_RATED_CAPACITY] * 10;

 	di->rated_capacity *= 1000; /* convert to µAh */

 	/* Calculate the full level at the present temperature. */
 	di->full_active_uAh = di->raw[DS2760_ACTIVE_FULL] << 8 |
 			      di->raw[DS2760_ACTIVE_FULL + 1];

 	/* If the full_active_uAh value is not given, fall back to the rated
 	 * capacity. This is likely to happen when chips are not part of the
 	 * battery pack and is therefore not bootstrapped. */
 	if (di->full_active_uAh == 0)
 		di->full_active_uAh = di->rated_capacity / 1000L;

 	scale[0] = di->full_active_uAh;
 	for (i = 1; i < 5; i++)
 		scale[i] = scale[i - 1] + di->raw[DS2760_ACTIVE_FULL + 2 + i];

 	di->full_active_uAh = battery_interpolate(scale, di->temp_C / 10);
 	di->full_active_uAh *= 1000; /* convert to µAh */

 	/* Calculate the empty level at the present temperature. */
 	scale[4] = di->raw[DS2760_ACTIVE_EMPTY + 4];
 	for (i = 3; i >= 0; i--)
 		scale[i] = scale[i + 1] + di->raw[DS2760_ACTIVE_EMPTY + i];

 	di->empty_uAh = battery_interpolate(scale, di->temp_C / 10);
 	di->empty_uAh *= 1000; /* convert to µAh */

 	if (di->full_active_uAh == di->empty_uAh)
 		di->rem_capacity = 0;
 	else
 		/* From Maxim Application Note 131: remaining capacity =
 		 * ((ICA - Empty Value) / (Full Value - Empty Value)) x 100% */
 		di->rem_capacity = ((di->accum_current_uAh - di->empty_uAh) * 100L) /
 				    (di->full_active_uAh - di->empty_uAh);

 	if (di->rem_capacity < 0)
 		di->rem_capacity = 0;
 	if (di->rem_capacity > 100)
 		di->rem_capacity = 100;

 	if (di->current_uA >= 100L)
 		di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * 36L)
 					/ (di->current_uA / 100L);
 	else
 		di->life_sec = 0;

 	return 0;
 }

 static void ds2760_battery_set_current_accum(struct ds2760_device_info *di,
 					     unsigned int acr_val)
 {
 	unsigned char acr[2];

 	/* acr is in units of 0.25 mAh */
 	acr_val *= 4L;
 	acr_val /= 1000;

 	acr[0] = acr_val >> 8;
 	acr[1] = acr_val & 0xff;

 	if (w1_ds2760_write(di->w1_dev, acr, DS2760_CURRENT_ACCUM_MSB, 2) < 2)
 		dev_warn(di->dev, "ACR write failed\n");
 }

 static void ds2760_battery_update_status(struct ds2760_device_info *di)
 {
 	int old_charge_status = di->charge_status;

 	ds2760_battery_read_status(di);

 	if (di->charge_status == POWER_SUPPLY_STATUS_UNKNOWN)
 		di->full_counter = 0;

 	if (power_supply_am_i_supplied(&di->bat)) {
 		if (di->current_uA > 10000) {
 			di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
 			di->full_counter = 0;
 		} else if (di->current_uA < -5000) {
 			if (di->charge_status != POWER_SUPPLY_STATUS_NOT_CHARGING)
 				dev_notice(di->dev, "not enough power to "
 					   "charge\n");
 			di->charge_status = POWER_SUPPLY_STATUS_NOT_CHARGING;
 			di->full_counter = 0;
 		} else if (di->current_uA < 10000 &&
 			    di->charge_status != POWER_SUPPLY_STATUS_FULL) {

 			/* Don't consider the battery to be full unless
 			 * we've seen the current < 10 mA at least two
 			 * consecutive times. */

 			di->full_counter++;

 			if (di->full_counter < 2) {
 				di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
 			} else {
 				di->charge_status = POWER_SUPPLY_STATUS_FULL;
 				ds2760_battery_set_current_accum(di,
 						di->full_active_uAh);
 			}
 		}
 	} else {
 		di->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
 		di->full_counter = 0;
 	}

 	if (di->charge_status != old_charge_status)
 		power_supply_changed(&di->bat);
 }

 static void ds2760_battery_write_status(struct ds2760_device_info *di,
 					char status)
 {
 	if (status == di->raw[DS2760_STATUS_REG])
 		return;

 	w1_ds2760_write(di->w1_dev, &status, DS2760_STATUS_WRITE_REG, 1);
 	w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 	w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 }

 static void ds2760_battery_write_rated_capacity(struct ds2760_device_info *di,
 						unsigned char rated_capacity)
 {
 	if (rated_capacity == di->raw[DS2760_RATED_CAPACITY])
 		return;

 	w1_ds2760_write(di->w1_dev, &rated_capacity, DS2760_RATED_CAPACITY, 1);
 	w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 	w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 }

 static void ds2760_battery_work(struct work_struct *work)
 {
 	struct ds2760_device_info *di = container_of(work,
 		struct ds2760_device_info, monitor_work.work);
 	const int interval = HZ * 60;

 	dev_dbg(di->dev, "%s\n", __func__);

 	ds2760_battery_update_status(di);
 	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, interval);
 }

 #define to_ds2760_device_info(x) container_of((x), struct ds2760_device_info, \
 					      bat);

 static void ds2760_battery_external_power_changed(struct power_supply *psy)
 {
 	struct ds2760_device_info *di = to_ds2760_device_info(psy);

 	dev_dbg(di->dev, "%s\n", __func__);

 	cancel_delayed_work(&di->monitor_work);
 	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ/10);
 }


 static void ds2760_battery_set_charged_work(struct work_struct *work)
 {
 	char bias;
 	struct ds2760_device_info *di = container_of(work,
 		struct ds2760_device_info, set_charged_work.work);

 	dev_dbg(di->dev, "%s\n", __func__);

 	ds2760_battery_read_status(di);

 	/* When we get notified by external circuitry that the battery is
 	 * considered fully charged now, we know that there is no current
 	 * flow any more. However, the ds2760's internal current meter is
 	 * too inaccurate to rely on - spec say something ~15% failure.
 	 * Hence, we use the current offset bias register to compensate
 	 * that error.
 	 */

 	if (!power_supply_am_i_supplied(&di->bat))
 		return;

 	bias = (signed char) di->current_raw +
 		(signed char) di->raw[DS2760_CURRENT_OFFSET_BIAS];

 	dev_dbg(di->dev, "%s: bias = %d\n", __func__, bias);

 	w1_ds2760_write(di->w1_dev, &bias, DS2760_CURRENT_OFFSET_BIAS, 1);
 	w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 	w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);

 	/* Write to the di->raw[] buffer directly - the CURRENT_OFFSET_BIAS
 	 * value won't be read back by ds2760_battery_read_status() */
 	di->raw[DS2760_CURRENT_OFFSET_BIAS] = bias;
 }

 static void ds2760_battery_set_charged(struct power_supply *psy)
 {
 	struct ds2760_device_info *di = to_ds2760_device_info(psy);

 	/* postpone the actual work by 20 secs. This is for debouncing GPIO
 	 * signals and to let the current value settle. See AN4188. */
 	cancel_delayed_work(&di->set_charged_work);
 	queue_delayed_work(di->monitor_wqueue, &di->set_charged_work, HZ * 20);
 }

 static int ds2760_battery_get_property(struct power_supply *psy,
 				       enum power_supply_property psp,
 				       union power_supply_propval *val)
 {
 	struct ds2760_device_info *di = to_ds2760_device_info(psy);

 	switch (psp) {
 	case POWER_SUPPLY_PROP_STATUS:
 		val->intval = di->charge_status;
 		return 0;
 	default:
 		break;
 	}

 	ds2760_battery_read_status(di);

 	switch (psp) {
 	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 		val->intval = di->voltage_uV;
 		break;
 	case POWER_SUPPLY_PROP_CURRENT_NOW:
 		val->intval = di->current_uA;
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
 		val->intval = di->rated_capacity;
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_FULL:
 		val->intval = di->full_active_uAh;
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_EMPTY:
 		val->intval = di->empty_uAh;
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_NOW:
 		val->intval = di->accum_current_uAh;
 		break;
 	case POWER_SUPPLY_PROP_TEMP:
 		val->intval = di->temp_C;
 		break;
 	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
 		val->intval = di->life_sec;
 		break;
 	case POWER_SUPPLY_PROP_CAPACITY:
 		val->intval = di->rem_capacity;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static enum power_supply_property ds2760_battery_props[] = {
 	POWER_SUPPLY_PROP_STATUS,
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
 	POWER_SUPPLY_PROP_CURRENT_NOW,
 	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
 	POWER_SUPPLY_PROP_CHARGE_FULL,
 	POWER_SUPPLY_PROP_CHARGE_EMPTY,
 	POWER_SUPPLY_PROP_CHARGE_NOW,
 	POWER_SUPPLY_PROP_TEMP,
 	POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
 	POWER_SUPPLY_PROP_CAPACITY,
 };

 static int ds2760_battery_probe(struct platform_device *pdev)
 {
 	char status;
 	int retval = 0;
 	struct ds2760_device_info *di;

 	di = kzalloc(sizeof(*di), GFP_KERNEL);
 	if (!di) {
 		retval = -ENOMEM;
 		goto di_alloc_failed;
 	}

 	platform_set_drvdata(pdev, di);

 	di->dev			= &pdev->dev;
 	di->w1_dev		= pdev->dev.parent;
 	di->bat.name		= dev_name(&pdev->dev);
 	di->bat.type		= POWER_SUPPLY_TYPE_BATTERY;
 	di->bat.properties	= ds2760_battery_props;
 	di->bat.num_properties	= ARRAY_SIZE(ds2760_battery_props);
 	di->bat.get_property	= ds2760_battery_get_property;
 	di->bat.set_charged	= ds2760_battery_set_charged;
 	di->bat.external_power_changed =
 				  ds2760_battery_external_power_changed;

 	di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;

 	/* enable sleep mode feature */
 	ds2760_battery_read_status(di);
 	status = di->raw[DS2760_STATUS_REG];
 	if (pmod_enabled)
 		status |= DS2760_STATUS_PMOD;
 	else
 		status &= ~DS2760_STATUS_PMOD;

 	ds2760_battery_write_status(di, status);

 	/* set rated capacity from module param */
 	if (rated_capacity)
 		ds2760_battery_write_rated_capacity(di, rated_capacity);

 	/* set current accumulator if given as parameter.
 	 * this should only be done for bootstrapping the value */
 	if (current_accum)
 		ds2760_battery_set_current_accum(di, current_accum);

 	retval = power_supply_register(&pdev->dev, &di->bat);
 	if (retval) {
 		dev_err(di->dev, "failed to register battery\n");
 		goto batt_failed;
 	}

 	INIT_DELAYED_WORK(&di->monitor_work, ds2760_battery_work);
 	INIT_DELAYED_WORK(&di->set_charged_work,
 			  ds2760_battery_set_charged_work);
 	di->monitor_wqueue = create_singlethread_workqueue(dev_name(&pdev->dev));
 	if (!di->monitor_wqueue) {
 		retval = -ESRCH;
 		goto workqueue_failed;
 	}
 	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ * 1);

 	goto success;

 workqueue_failed:
 	power_supply_unregister(&di->bat);
 batt_failed:
 	kfree(di);
 di_alloc_failed:
 success:
 	return retval;
 }

 static int ds2760_battery_remove(struct platform_device *pdev)
 {
 	struct ds2760_device_info *di = platform_get_drvdata(pdev);

 	cancel_rearming_delayed_workqueue(di->monitor_wqueue,
 					  &di->monitor_work);
 	cancel_rearming_delayed_workqueue(di->monitor_wqueue,
 					  &di->set_charged_work);
 	destroy_workqueue(di->monitor_wqueue);
 	power_supply_unregister(&di->bat);

 	return 0;
 }

 #ifdef CONFIG_PM

 static int ds2760_battery_suspend(struct platform_device *pdev,
 				  pm_message_t state)
 {
 	struct ds2760_device_info *di = platform_get_drvdata(pdev);

 	di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;

 	return 0;
 }

 static int ds2760_battery_resume(struct platform_device *pdev)
 {
 	struct ds2760_device_info *di = platform_get_drvdata(pdev);

 	di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;
 	power_supply_changed(&di->bat);

 	cancel_delayed_work(&di->monitor_work);
 	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ);

 	return 0;
 }

 #else

 #define ds2760_battery_suspend NULL
 #define ds2760_battery_resume NULL

 #endif /* CONFIG_PM */

 MODULE_ALIAS("platform:ds2760-battery");

 static struct platform_driver ds2760_battery_driver = {
 	.driver = {
 		.name = "ds2760-battery",
 	},
 	.probe	  = ds2760_battery_probe,
 	.remove   = ds2760_battery_remove,
 	.suspend  = ds2760_battery_suspend,
 	.resume	  = ds2760_battery_resume,
 };

 static int __init ds2760_battery_init(void)
 {
 	return platform_driver_register(&ds2760_battery_driver);
 }

 static void __exit ds2760_battery_exit(void)
 {
 	platform_driver_unregister(&ds2760_battery_driver);
 }

 module_init(ds2760_battery_init);
 module_exit(ds2760_battery_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>, "
 	      "Matt Reimer <mreimer@vpop.net>, "
 	      "Anton Vorontsov <cbou@mail.ru>");
 MODULE_DESCRIPTION("ds2760 battery driver");
	/*
	* Driver for batteries with DS2760 chips inside.
	*
	* Copyright © 2007 Anton Vorontsov
	* 2004-2007 Matt Reimer
	* 2004 Szabolcs Gyurko
	*
	* Use consistent with the GNU GPL is permitted,
	* provided that this copyright notice is
	* preserved in its entirety in all copies and derived works.
	*
	* Author: Anton Vorontsov <cbou@mail.ru>
	* February 2007
	*
	* Matt Reimer <mreimer@vpop.net>
	* April 2004, 2005, 2007
	*
	* Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
	* September 2004
	*/

	#include <linux/module.h>
	#include <linux/param.h>
	#include <linux/jiffies.h>
	#include <linux/workqueue.h>
	#include <linux/pm.h>
	#include <linux/platform_device.h>
	#include <linux/power_supply.h>

	#include "../w1/w1.h"
	#include "../w1/slaves/w1_ds2760.h"

	struct ds2760_device_info {
	struct device *dev;

	/* DS2760 data, valid after calling ds2760_battery_read_status() */
	unsigned long update_time; /* jiffies when data read */
	char raw[DS2760_DATA_SIZE]; /* raw DS2760 data */
	int voltage_raw; /* units of 4.88 mV */
	int voltage_uV; /* units of µV */
	int current_raw; /* units of 0.625 mA */
	int current_uA; /* units of µA */
	int accum_current_raw; /* units of 0.25 mAh */
	int accum_current_uAh; /* units of µAh */
	int temp_raw; /* units of 0.125 °C */
	int temp_C; /* units of 0.1 °C */
	int rated_capacity; /* units of µAh */
	int rem_capacity; /* percentage */
	int full_active_uAh; /* units of µAh */
	int empty_uAh; /* units of µAh */
	int life_sec; /* units of seconds */
	int charge_status; /* POWER_SUPPLY_STATUS_* */

	int full_counter;
	struct power_supply bat;
	struct device *w1_dev;
	struct workqueue_struct *monitor_wqueue;
	struct delayed_work monitor_work;
	struct delayed_work set_charged_work;
	};

	static unsigned int cache_time = 1000;
	module_param(cache_time, uint, 0644);
	MODULE_PARM_DESC(cache_time, "cache time in milliseconds");

	static unsigned int pmod_enabled;
	module_param(pmod_enabled, bool, 0644);
	MODULE_PARM_DESC(pmod_enabled, "PMOD enable bit");

	static unsigned int rated_capacity;
	module_param(rated_capacity, uint, 0644);
	MODULE_PARM_DESC(rated_capacity, "rated battery capacity, 10*mAh or index");

	static unsigned int current_accum;
	module_param(current_accum, uint, 0644);
	MODULE_PARM_DESC(current_accum, "current accumulator value");

	/* Some batteries have their rated capacity stored a N * 10 mAh, while
	* others use an index into this table. */
	static int rated_capacities[] = {
	0,
	920, /* Samsung */
	920, /* BYD */
	920, /* Lishen */
	920, /* NEC */
	1440, /* Samsung */
	1440, /* BYD */
	1440, /* Lishen */
	1440, /* NEC */
	2880, /* Samsung */
	2880, /* BYD */
	2880, /* Lishen */
	2880 /* NEC */
	};

	/* array is level at temps 0°C, 10°C, 20°C, 30°C, 40°C
	* temp is in Celsius */
	static int battery_interpolate(int array[], int temp)
	{
	int index, dt;

	if (temp <= 0)
	return array[0];
	if (temp >= 40)
	return array[4];

	index = temp / 10;
	dt = temp % 10;

	return array[index] + (((array[index + 1] - array[index]) * dt) / 10);
	}

	static int ds2760_battery_read_status(struct ds2760_device_info *di)
	{
	int ret, i, start, count, scale[5];

	if (di->update_time && time_before(jiffies, di->update_time +
	msecs_to_jiffies(cache_time)))
	return 0;

	/* The first time we read the entire contents of SRAM/EEPROM,
	* but after that we just read the interesting bits that change. */
	if (di->update_time == 0) {
	start = 0;
	count = DS2760_DATA_SIZE;
	} else {
	start = DS2760_VOLTAGE_MSB;
	count = DS2760_TEMP_LSB - start + 1;
	}

	ret = w1_ds2760_read(di->w1_dev, di->raw + start, start, count);
	if (ret != count) {
	dev_warn(di->dev, "call to w1_ds2760_read failed (0x%p)\n",
	di->w1_dev);
	return 1;
	}

	di->update_time = jiffies;

	/* DS2760 reports voltage in units of 4.88mV, but the battery class
	* reports in units of uV, so convert by multiplying by 4880. */
	di->voltage_raw = (di->raw[DS2760_VOLTAGE_MSB] << 3) \|
	(di->raw[DS2760_VOLTAGE_LSB] >> 5);
	di->voltage_uV = di->voltage_raw * 4880;

	/* DS2760 reports current in signed units of 0.625mA, but the battery
	* class reports in units of µA, so convert by multiplying by 625. */
	di->current_raw =
	(((signed char)di->raw[DS2760_CURRENT_MSB]) << 5) \|
	(di->raw[DS2760_CURRENT_LSB] >> 3);
	di->current_uA = di->current_raw * 625;

	/* DS2760 reports accumulated current in signed units of 0.25mAh. */
	di->accum_current_raw =
	(((signed char)di->raw[DS2760_CURRENT_ACCUM_MSB]) << 8) \|
	di->raw[DS2760_CURRENT_ACCUM_LSB];
	di->accum_current_uAh = di->accum_current_raw * 250;

	/* DS2760 reports temperature in signed units of 0.125°C, but the
	* battery class reports in units of 1/10 °C, so we convert by
	* multiplying by .125 * 10 = 1.25. */
	di->temp_raw = (((signed char)di->raw[DS2760_TEMP_MSB]) << 3) \|
	(di->raw[DS2760_TEMP_LSB] >> 5);
	di->temp_C = di->temp_raw + (di->temp_raw / 4);

	/* At least some battery monitors (e.g. HP iPAQ) store the battery's
	* maximum rated capacity. */
	if (di->raw[DS2760_RATED_CAPACITY] < ARRAY_SIZE(rated_capacities))
	di->rated_capacity = rated_capacities[
	(unsigned int)di->raw[DS2760_RATED_CAPACITY]];
	else
	di->rated_capacity = di->raw[DS2760_RATED_CAPACITY] * 10;

	di->rated_capacity = 1000; / convert to µAh */

	/* Calculate the full level at the present temperature. */
	di->full_active_uAh = di->raw[DS2760_ACTIVE_FULL] << 8 \|
	di->raw[DS2760_ACTIVE_FULL + 1];

	/* If the full_active_uAh value is not given, fall back to the rated
	* capacity. This is likely to happen when chips are not part of the
	* battery pack and is therefore not bootstrapped. */
	if (di->full_active_uAh == 0)
	di->full_active_uAh = di->rated_capacity / 1000L;

	scale[0] = di->full_active_uAh;
	for (i = 1; i < 5; i++)
	scale[i] = scale[i - 1] + di->raw[DS2760_ACTIVE_FULL + 2 + i];

	di->full_active_uAh = battery_interpolate(scale, di->temp_C / 10);
	di->full_active_uAh = 1000; / convert to µAh */

	/* Calculate the empty level at the present temperature. */
	scale[4] = di->raw[DS2760_ACTIVE_EMPTY + 4];
	for (i = 3; i >= 0; i--)
	scale[i] = scale[i + 1] + di->raw[DS2760_ACTIVE_EMPTY + i];

	di->empty_uAh = battery_interpolate(scale, di->temp_C / 10);
	di->empty_uAh = 1000; / convert to µAh */

	if (di->full_active_uAh == di->empty_uAh)
	di->rem_capacity = 0;
	else
	/* From Maxim Application Note 131: remaining capacity =
	* ((ICA - Empty Value) / (Full Value - Empty Value)) x 100% */
	di->rem_capacity = ((di->accum_current_uAh - di->empty_uAh) * 100L) /
	(di->full_active_uAh - di->empty_uAh);

	if (di->rem_capacity < 0)
	di->rem_capacity = 0;
	if (di->rem_capacity > 100)
	di->rem_capacity = 100;

	if (di->current_uA >= 100L)
	di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * 36L)
	/ (di->current_uA / 100L);
	else
	di->life_sec = 0;

	return 0;
	}

	static void ds2760_battery_set_current_accum(struct ds2760_device_info *di,
	unsigned int acr_val)
	{
	unsigned char acr[2];

	/* acr is in units of 0.25 mAh */
	acr_val *= 4L;
	acr_val /= 1000;

	acr[0] = acr_val >> 8;
	acr[1] = acr_val & 0xff;

	if (w1_ds2760_write(di->w1_dev, acr, DS2760_CURRENT_ACCUM_MSB, 2) < 2)
	dev_warn(di->dev, "ACR write failed\n");
	}

	static void ds2760_battery_update_status(struct ds2760_device_info *di)
	{
	int old_charge_status = di->charge_status;

	ds2760_battery_read_status(di);

	if (di->charge_status == POWER_SUPPLY_STATUS_UNKNOWN)
	di->full_counter = 0;

	if (power_supply_am_i_supplied(&di->bat)) {
	if (di->current_uA > 10000) {
	di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
	di->full_counter = 0;
	} else if (di->current_uA < -5000) {
	if (di->charge_status != POWER_SUPPLY_STATUS_NOT_CHARGING)
	dev_notice(di->dev, "not enough power to "
	"charge\n");
	di->charge_status = POWER_SUPPLY_STATUS_NOT_CHARGING;
	di->full_counter = 0;
	} else if (di->current_uA < 10000 &&
	di->charge_status != POWER_SUPPLY_STATUS_FULL) {

	/* Don't consider the battery to be full unless
	* we've seen the current < 10 mA at least two
	* consecutive times. */

	di->full_counter++;

	if (di->full_counter < 2) {
	di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
	} else {
	di->charge_status = POWER_SUPPLY_STATUS_FULL;
	ds2760_battery_set_current_accum(di,
	di->full_active_uAh);
	}
	}
	} else {
	di->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
	di->full_counter = 0;
	}

	if (di->charge_status != old_charge_status)
	power_supply_changed(&di->bat);
	}

	static void ds2760_battery_write_status(struct ds2760_device_info *di,
	char status)
	{
	if (status == di->raw[DS2760_STATUS_REG])
	return;

	w1_ds2760_write(di->w1_dev, &status, DS2760_STATUS_WRITE_REG, 1);
	w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
	w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
	}

	static void ds2760_battery_write_rated_capacity(struct ds2760_device_info *di,
	unsigned char rated_capacity)
	{
	if (rated_capacity == di->raw[DS2760_RATED_CAPACITY])
	return;

	w1_ds2760_write(di->w1_dev, &rated_capacity, DS2760_RATED_CAPACITY, 1);
	w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
	w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
	}

	static void ds2760_battery_work(struct work_struct *work)
	{
	struct ds2760_device_info *di = container_of(work,
	struct ds2760_device_info, monitor_work.work);
	const int interval = HZ * 60;

	dev_dbg(di->dev, "%s\n", __func__);

	ds2760_battery_update_status(di);
	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, interval);
	}

	#define to_ds2760_device_info(x) container_of((x), struct ds2760_device_info, \
	bat);

	static void ds2760_battery_external_power_changed(struct power_supply *psy)
	{
	struct ds2760_device_info *di = to_ds2760_device_info(psy);

	dev_dbg(di->dev, "%s\n", __func__);

	cancel_delayed_work(&di->monitor_work);
	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ/10);
	}


	static void ds2760_battery_set_charged_work(struct work_struct *work)
	{
	char bias;
	struct ds2760_device_info *di = container_of(work,
	struct ds2760_device_info, set_charged_work.work);

	dev_dbg(di->dev, "%s\n", __func__);

	ds2760_battery_read_status(di);

	/* When we get notified by external circuitry that the battery is
	* considered fully charged now, we know that there is no current
	* flow any more. However, the ds2760's internal current meter is
	* too inaccurate to rely on - spec say something ~15% failure.
	* Hence, we use the current offset bias register to compensate
	* that error.
	*/

	if (!power_supply_am_i_supplied(&di->bat))
	return;

	bias = (signed char) di->current_raw +
	(signed char) di->raw[DS2760_CURRENT_OFFSET_BIAS];

	dev_dbg(di->dev, "%s: bias = %d\n", __func__, bias);

	w1_ds2760_write(di->w1_dev, &bias, DS2760_CURRENT_OFFSET_BIAS, 1);
	w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
	w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);

	/* Write to the di->raw[] buffer directly - the CURRENT_OFFSET_BIAS
	* value won't be read back by ds2760_battery_read_status() */
	di->raw[DS2760_CURRENT_OFFSET_BIAS] = bias;
	}

	static void ds2760_battery_set_charged(struct power_supply *psy)
	{
	struct ds2760_device_info *di = to_ds2760_device_info(psy);

	/* postpone the actual work by 20 secs. This is for debouncing GPIO
	* signals and to let the current value settle. See AN4188. */
	cancel_delayed_work(&di->set_charged_work);
	queue_delayed_work(di->monitor_wqueue, &di->set_charged_work, HZ * 20);
	}

	static int ds2760_battery_get_property(struct power_supply *psy,
	enum power_supply_property psp,
	union power_supply_propval *val)
	{
	struct ds2760_device_info *di = to_ds2760_device_info(psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_STATUS:
	val->intval = di->charge_status;
	return 0;
	default:
	break;
	}

	ds2760_battery_read_status(di);

	switch (psp) {
	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
	val->intval = di->voltage_uV;
	break;
	case POWER_SUPPLY_PROP_CURRENT_NOW:
	val->intval = di->current_uA;
	break;
	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
	val->intval = di->rated_capacity;
	break;
	case POWER_SUPPLY_PROP_CHARGE_FULL:
	val->intval = di->full_active_uAh;
	break;
	case POWER_SUPPLY_PROP_CHARGE_EMPTY:
	val->intval = di->empty_uAh;
	break;
	case POWER_SUPPLY_PROP_CHARGE_NOW:
	val->intval = di->accum_current_uAh;
	break;
	case POWER_SUPPLY_PROP_TEMP:
	val->intval = di->temp_C;
	break;
	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
	val->intval = di->life_sec;
	break;
	case POWER_SUPPLY_PROP_CAPACITY:
	val->intval = di->rem_capacity;
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	static enum power_supply_property ds2760_battery_props[] = {
	POWER_SUPPLY_PROP_STATUS,
	POWER_SUPPLY_PROP_VOLTAGE_NOW,
	POWER_SUPPLY_PROP_CURRENT_NOW,
	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
	POWER_SUPPLY_PROP_CHARGE_FULL,
	POWER_SUPPLY_PROP_CHARGE_EMPTY,
	POWER_SUPPLY_PROP_CHARGE_NOW,
	POWER_SUPPLY_PROP_TEMP,
	POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
	POWER_SUPPLY_PROP_CAPACITY,
	};

	static int ds2760_battery_probe(struct platform_device *pdev)
	{
	char status;
	int retval = 0;
	struct ds2760_device_info *di;

	di = kzalloc(sizeof(*di), GFP_KERNEL);
	if (!di) {
	retval = -ENOMEM;
	goto di_alloc_failed;
	}

	platform_set_drvdata(pdev, di);

	di->dev = &pdev->dev;
	di->w1_dev = pdev->dev.parent;
	di->bat.name = dev_name(&pdev->dev);
	di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
	di->bat.properties = ds2760_battery_props;
	di->bat.num_properties = ARRAY_SIZE(ds2760_battery_props);
	di->bat.get_property = ds2760_battery_get_property;
	di->bat.set_charged = ds2760_battery_set_charged;
	di->bat.external_power_changed =
	ds2760_battery_external_power_changed;

	di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;

	/* enable sleep mode feature */
	ds2760_battery_read_status(di);
	status = di->raw[DS2760_STATUS_REG];
	if (pmod_enabled)
	status \|= DS2760_STATUS_PMOD;
	else
	status &= ~DS2760_STATUS_PMOD;

	ds2760_battery_write_status(di, status);

	/* set rated capacity from module param */
	if (rated_capacity)
	ds2760_battery_write_rated_capacity(di, rated_capacity);

	/* set current accumulator if given as parameter.
	* this should only be done for bootstrapping the value */
	if (current_accum)
	ds2760_battery_set_current_accum(di, current_accum);

	retval = power_supply_register(&pdev->dev, &di->bat);
	if (retval) {
	dev_err(di->dev, "failed to register battery\n");
	goto batt_failed;
	}

	INIT_DELAYED_WORK(&di->monitor_work, ds2760_battery_work);
	INIT_DELAYED_WORK(&di->set_charged_work,
	ds2760_battery_set_charged_work);
	di->monitor_wqueue = create_singlethread_workqueue(dev_name(&pdev->dev));
	if (!di->monitor_wqueue) {
	retval = -ESRCH;
	goto workqueue_failed;
	}
	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ * 1);

	goto success;

	workqueue_failed:
	power_supply_unregister(&di->bat);
	batt_failed:
	kfree(di);
	di_alloc_failed:
	success:
	return retval;
	}

	static int ds2760_battery_remove(struct platform_device *pdev)
	{
	struct ds2760_device_info *di = platform_get_drvdata(pdev);

	cancel_rearming_delayed_workqueue(di->monitor_wqueue,
	&di->monitor_work);
	cancel_rearming_delayed_workqueue(di->monitor_wqueue,
	&di->set_charged_work);
	destroy_workqueue(di->monitor_wqueue);
	power_supply_unregister(&di->bat);

	return 0;
	}

	#ifdef CONFIG_PM

	static int ds2760_battery_suspend(struct platform_device *pdev,
	pm_message_t state)
	{
	struct ds2760_device_info *di = platform_get_drvdata(pdev);

	di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;

	return 0;
	}

	static int ds2760_battery_resume(struct platform_device *pdev)
	{
	struct ds2760_device_info *di = platform_get_drvdata(pdev);

	di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;
	power_supply_changed(&di->bat);

	cancel_delayed_work(&di->monitor_work);
	queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ);

	return 0;
	}

	#else

	#define ds2760_battery_suspend NULL
	#define ds2760_battery_resume NULL

	#endif /* CONFIG_PM */

	MODULE_ALIAS("platform:ds2760-battery");

	static struct platform_driver ds2760_battery_driver = {
	.driver = {
	.name = "ds2760-battery",
	},
	.probe = ds2760_battery_probe,
	.remove = ds2760_battery_remove,
	.suspend = ds2760_battery_suspend,
	.resume = ds2760_battery_resume,
	};

	static int __init ds2760_battery_init(void)
	{
	return platform_driver_register(&ds2760_battery_driver);
	}

	static void __exit ds2760_battery_exit(void)
	{
	platform_driver_unregister(&ds2760_battery_driver);
	}

	module_init(ds2760_battery_init);
	module_exit(ds2760_battery_exit);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>, "
	"Matt Reimer <mreimer@vpop.net>, "
	"Anton Vorontsov <cbou@mail.ru>");
	MODULE_DESCRIPTION("ds2760 battery driver");