Merge branch 'bq27x00-for-upstream' of git://git.metafoo.de/linux-2.6

5 files changed, 593 insertions, 171 deletions

diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 61bf5d724139..52a462fc6b84 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -117,10 +117,24 @@ config BATTERY_BQ20Z75
 
 config BATTERY_BQ27x00
 	tristate "BQ27x00 battery driver"
+	help
+	  Say Y here to enable support for batteries with BQ27x00 (I2C/HDQ) chips.
+
+config BATTERY_BQ27X00_I2C
+	bool "BQ27200/BQ27500 support"
+	depends on BATTERY_BQ27x00
 	depends on I2C
+	default y
 	help
 	  Say Y here to enable support for batteries with BQ27x00 (I2C) chips.
 
+config BATTERY_BQ27X00_PLATFORM
+	bool "BQ27000 support"
+	depends on BATTERY_BQ27x00
+	default y
+	help
+	  Say Y here to enable support for batteries with BQ27000 (HDQ) chips.
+
 config BATTERY_DA9030
 	tristate "DA9030 battery driver"
 	depends on PMIC_DA903X
diff --git a/drivers/power/bq27x00_battery.c b/drivers/power/bq27x00_battery.c
index eff0273d4030..59e68dbd028b 100644
--- a/drivers/power/bq27x00_battery.c
+++ b/drivers/power/bq27x00_battery.c
@@ -3,6 +3,7 @@
  *
  * Copyright (C) 2008 Rodolfo Giometti <giometti@linux.it>
  * Copyright (C) 2008 Eurotech S.p.A. <info@eurotech.it>
+ * Copyright (C) 2010-2011 Lars-Peter Clausen <lars@metafoo.de>
  *
  * Based on a previous work by Copyright (C) 2008 Texas Instruments, Inc.
  *
@@ -15,6 +16,13 @@
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
  */
+
+/*
+ * Datasheets:
+ * http://focus.ti.com/docs/prod/folders/print/bq27000.html
+ * http://focus.ti.com/docs/prod/folders/print/bq27500.html
+ */
+
 #include <linux/module.h>
 #include <linux/param.h>
 #include <linux/jiffies.h>
@@ -27,7 +35,9 @@
 #include <linux/slab.h>
 #include <asm/unaligned.h>
 
-#define DRIVER_VERSION			"1.1.0"
+#include <linux/power/bq27x00_battery.h>
+
+#define DRIVER_VERSION			"1.2.0"
 
 #define BQ27x00_REG_TEMP		0x06
 #define BQ27x00_REG_VOLT		0x08
@@ -36,36 +46,59 @@
 #define BQ27x00_REG_TTE			0x16
 #define BQ27x00_REG_TTF			0x18
 #define BQ27x00_REG_TTECP		0x26
+#define BQ27x00_REG_NAC			0x0C /* Nominal available capaciy */
+#define BQ27x00_REG_LMD			0x12 /* Last measured discharge */
+#define BQ27x00_REG_CYCT		0x2A /* Cycle count total */
+#define BQ27x00_REG_AE			0x22 /* Available enery */
 
 #define BQ27000_REG_RSOC		0x0B /* Relative State-of-Charge */
+#define BQ27000_REG_ILMD		0x76 /* Initial last measured discharge */
 #define BQ27000_FLAG_CHGS		BIT(7)
+#define BQ27000_FLAG_FC			BIT(5)
 
-#define BQ27500_REG_SOC			0x2c
+#define BQ27500_REG_SOC			0x2C
+#define BQ27500_REG_DCAP		0x3C /* Design capacity */
 #define BQ27500_FLAG_DSC		BIT(0)
 #define BQ27500_FLAG_FC			BIT(9)
 
-/* If the system has several batteries we need a different name for each
- * of them...
- */
-static DEFINE_IDR(battery_id);
-static DEFINE_MUTEX(battery_mutex);
+#define BQ27000_RS			20 /* Resistor sense */
 
 struct bq27x00_device_info;
 struct bq27x00_access_methods {
-	int (*read)(u8 reg, int *rt_value, int b_single,
-		struct bq27x00_device_info *di);
+	int (*read)(struct bq27x00_device_info *di, u8 reg, bool single);
 };
 
 enum bq27x00_chip { BQ27000, BQ27500 };
 
+struct bq27x00_reg_cache {
+	int temperature;
+	int time_to_empty;
+	int time_to_empty_avg;
+	int time_to_full;
+	int charge_full;
+	int charge_counter;
+	int capacity;
+	int flags;
+
+	int current_now;
+};
+
 struct bq27x00_device_info {
 	struct device 		*dev;
 	int			id;
-	struct bq27x00_access_methods	*bus;
-	struct power_supply	bat;
 	enum bq27x00_chip	chip;
 
-	struct i2c_client	*client;
+	struct bq27x00_reg_cache cache;
+	int charge_design_full;
+
+	unsigned long last_update;
+	struct delayed_work work;
+
+	struct power_supply	bat;
+
+	struct bq27x00_access_methods bus;
+
+	struct mutex lock;
 };
 
 static enum power_supply_property bq27x00_battery_props[] = {
@@ -78,164 +111,328 @@ static enum power_supply_property bq27x00_battery_props[] = {
 	POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
 	POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
 	POWER_SUPPLY_PROP_TIME_TO_FULL_NOW,
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_CHARGE_FULL,
+	POWER_SUPPLY_PROP_CHARGE_NOW,
+	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+	POWER_SUPPLY_PROP_CHARGE_COUNTER,
+	POWER_SUPPLY_PROP_ENERGY_NOW,
 };
 
+static unsigned int poll_interval = 360;
+module_param(poll_interval, uint, 0644);
+MODULE_PARM_DESC(poll_interval, "battery poll interval in seconds - " \
+				"0 disables polling");
+
 /*
  * Common code for BQ27x00 devices
  */
 
-static int bq27x00_read(u8 reg, int *rt_value, int b_single,
-			struct bq27x00_device_info *di)
+static inline int bq27x00_read(struct bq27x00_device_info *di, u8 reg,
+		bool single)
 {
-	return di->bus->read(reg, rt_value, b_single, di);
+	return di->bus.read(di, reg, single);
 }
 
 /*
- * Return the battery temperature in tenths of degree Celsius
+ * Return the battery Relative State-of-Charge
  * Or < 0 if something fails.
  */
-static int bq27x00_battery_temperature(struct bq27x00_device_info *di)
+static int bq27x00_battery_read_rsoc(struct bq27x00_device_info *di)
 {
-	int ret;
-	int temp = 0;
+	int rsoc;
 
-	ret = bq27x00_read(BQ27x00_REG_TEMP, &temp, 0, di);
-	if (ret) {
-		dev_err(di->dev, "error reading temperature\n");
-		return ret;
+	if (di->chip == BQ27500)
+		rsoc = bq27x00_read(di, BQ27500_REG_SOC, false);
+	else
+		rsoc = bq27x00_read(di, BQ27000_REG_RSOC, true);
+
+	if (rsoc < 0)
+		dev_err(di->dev, "error reading relative State-of-Charge\n");
+
+	return rsoc;
+}
+
+/*
+ * Return a battery charge value in µAh
+ * Or < 0 if something fails.
+ */
+static int bq27x00_battery_read_charge(struct bq27x00_device_info *di, u8 reg)
+{
+	int charge;
+
+	charge = bq27x00_read(di, reg, false);
+	if (charge < 0) {
+		dev_err(di->dev, "error reading nominal available capacity\n");
+		return charge;
 	}
 
 	if (di->chip == BQ27500)
-		return temp - 2731;
+		charge *= 1000;
 	else
-		return ((temp >> 2) - 273) * 10;
+		charge = charge * 3570 / BQ27000_RS;
+
+	return charge;
 }
 
 /*
- * Return the battery Voltage in milivolts
+ * Return the battery Nominal available capaciy in µAh
  * Or < 0 if something fails.
  */
-static int bq27x00_battery_voltage(struct bq27x00_device_info *di)
+static inline int bq27x00_battery_read_nac(struct bq27x00_device_info *di)
 {
-	int ret;
-	int volt = 0;
+	return bq27x00_battery_read_charge(di, BQ27x00_REG_NAC);
+}
 
-	ret = bq27x00_read(BQ27x00_REG_VOLT, &volt, 0, di);
-	if (ret) {
-		dev_err(di->dev, "error reading voltage\n");
-		return ret;
+/*
+ * Return the battery Last measured discharge in µAh
+ * Or < 0 if something fails.
+ */
+static inline int bq27x00_battery_read_lmd(struct bq27x00_device_info *di)
+{
+	return bq27x00_battery_read_charge(di, BQ27x00_REG_LMD);
+}
+
+/*
+ * Return the battery Initial last measured discharge in µAh
+ * Or < 0 if something fails.
+ */
+static int bq27x00_battery_read_ilmd(struct bq27x00_device_info *di)
+{
+	int ilmd;
+
+	if (di->chip == BQ27500)
+		ilmd = bq27x00_read(di, BQ27500_REG_DCAP, false);
+	else
+		ilmd = bq27x00_read(di, BQ27000_REG_ILMD, true);
+
+	if (ilmd < 0) {
+		dev_err(di->dev, "error reading initial last measured discharge\n");
+		return ilmd;
 	}
 
-	return volt * 1000;
+	if (di->chip == BQ27500)
+		ilmd *= 1000;
+	else
+		ilmd = ilmd * 256 * 3570 / BQ27000_RS;
+
+	return ilmd;
 }
 
 /*
- * Return the battery average current
- * Note that current can be negative signed as well
- * Or 0 if something fails.
+ * Return the battery Cycle count total
+ * Or < 0 if something fails.
  */
-static int bq27x00_battery_current(struct bq27x00_device_info *di)
+static int bq27x00_battery_read_cyct(struct bq27x00_device_info *di)
 {
-	int ret;
-	int curr = 0;
-	int flags = 0;
+	int cyct;
 
-	ret = bq27x00_read(BQ27x00_REG_AI, &curr, 0, di);
-	if (ret) {
-		dev_err(di->dev, "error reading current\n");
-		return 0;
+	cyct = bq27x00_read(di, BQ27x00_REG_CYCT, false);
+	if (cyct < 0)
+		dev_err(di->dev, "error reading cycle count total\n");
+
+	return cyct;
+}
+
+/*
+ * Read a time register.
+ * Return < 0 if something fails.
+ */
+static int bq27x00_battery_read_time(struct bq27x00_device_info *di, u8 reg)
+{
+	int tval;
+
+	tval = bq27x00_read(di, reg, false);
+	if (tval < 0) {
+		dev_err(di->dev, "error reading register %02x: %d\n", reg, tval);
+		return tval;
 	}
 
-	if (di->chip == BQ27500) {
-		/* bq27500 returns signed value */
-		curr = (int)(s16)curr;
-	} else {
-		ret = bq27x00_read(BQ27x00_REG_FLAGS, &flags, 0, di);
-		if (ret < 0) {
-			dev_err(di->dev, "error reading flags\n");
-			return 0;
-		}
-		if (flags & BQ27000_FLAG_CHGS) {
-			dev_dbg(di->dev, "negative current!\n");
-			curr = -curr;
-		}
+	if (tval == 65535)
+		return -ENODATA;
+
+	return tval * 60;
+}
+
+static void bq27x00_update(struct bq27x00_device_info *di)
+{
+	struct bq27x00_reg_cache cache = {0, };
+	bool is_bq27500 = di->chip == BQ27500;
+
+	cache.flags = bq27x00_read(di, BQ27x00_REG_FLAGS, is_bq27500);
+	if (cache.flags >= 0) {
+		cache.capacity = bq27x00_battery_read_rsoc(di);
+		cache.temperature = bq27x00_read(di, BQ27x00_REG_TEMP, false);
+		cache.time_to_empty = bq27x00_battery_read_time(di, BQ27x00_REG_TTE);
+		cache.time_to_empty_avg = bq27x00_battery_read_time(di, BQ27x00_REG_TTECP);
+		cache.time_to_full = bq27x00_battery_read_time(di, BQ27x00_REG_TTF);
+		cache.charge_full = bq27x00_battery_read_lmd(di);
+		cache.charge_counter = bq27x00_battery_read_cyct(di);
+
+		if (!is_bq27500)
+			cache.current_now = bq27x00_read(di, BQ27x00_REG_AI, false);
+
+		/* We only have to read charge design full once */
+		if (di->charge_design_full <= 0)
+			di->charge_design_full = bq27x00_battery_read_ilmd(di);
+	}
+
+	/* Ignore current_now which is a snapshot of the current battery state
+	 * and is likely to be different even between two consecutive reads */
+	if (memcmp(&di->cache, &cache, sizeof(cache) - sizeof(int)) != 0) {
+		di->cache = cache;
+		power_supply_changed(&di->bat);
 	}
 
-	return curr * 1000;
+	di->last_update = jiffies;
+}
+
+static void bq27x00_battery_poll(struct work_struct *work)
+{
+	struct bq27x00_device_info *di =
+		container_of(work, struct bq27x00_device_info, work.work);
+
+	bq27x00_update(di);
+
+	if (poll_interval > 0) {
+		/* The timer does not have to be accurate. */
+		set_timer_slack(&di->work.timer, poll_interval * HZ / 4);
+		schedule_delayed_work(&di->work, poll_interval * HZ);
+	}
 }
 
+
 /*
- * Return the battery Relative State-of-Charge
+ * Return the battery temperature in tenths of degree Celsius
  * Or < 0 if something fails.
  */
-static int bq27x00_battery_rsoc(struct bq27x00_device_info *di)
+static int bq27x00_battery_temperature(struct bq27x00_device_info *di,
+	union power_supply_propval *val)
 {
-	int ret;
-	int rsoc = 0;
+	if (di->cache.temperature < 0)
+		return di->cache.temperature;
 
 	if (di->chip == BQ27500)
-		ret = bq27x00_read(BQ27500_REG_SOC, &rsoc, 0, di);
+		val->intval = di->cache.temperature - 2731;
 	else
-		ret = bq27x00_read(BQ27000_REG_RSOC, &rsoc, 1, di);
-	if (ret) {
-		dev_err(di->dev, "error reading relative State-of-Charge\n");
-		return ret;
+		val->intval = ((di->cache.temperature * 5) - 5463) / 2;
+
+	return 0;
+}
+
+/*
+ * Return the battery average current in µA
+ * Note that current can be negative signed as well
+ * Or 0 if something fails.
+ */
+static int bq27x00_battery_current(struct bq27x00_device_info *di,
+	union power_supply_propval *val)
+{
+	int curr;
+
+	if (di->chip == BQ27500)
+	    curr = bq27x00_read(di, BQ27x00_REG_AI, false);
+	else
+	    curr = di->cache.current_now;
+
+	if (curr < 0)
+		return curr;
+
+	if (di->chip == BQ27500) {
+		/* bq27500 returns signed value */
+		val->intval = (int)((s16)curr) * 1000;
+	} else {
+		if (di->cache.flags & BQ27000_FLAG_CHGS) {
+			dev_dbg(di->dev, "negative current!\n");
+			curr = -curr;
+		}
+
+		val->intval = curr * 3570 / BQ27000_RS;
 	}
 
-	return rsoc;
+	return 0;
 }
 
 static int bq27x00_battery_status(struct bq27x00_device_info *di,
-				  union power_supply_propval *val)
+	union power_supply_propval *val)
 {
-	int flags = 0;
 	int status;
-	int ret;
-
-	ret = bq27x00_read(BQ27x00_REG_FLAGS, &flags, 0, di);
-	if (ret < 0) {
-		dev_err(di->dev, "error reading flags\n");
-		return ret;
-	}
 
 	if (di->chip == BQ27500) {
-		if (flags & BQ27500_FLAG_FC)
+		if (di->cache.flags & BQ27500_FLAG_FC)
 			status = POWER_SUPPLY_STATUS_FULL;
-		else if (flags & BQ27500_FLAG_DSC)
+		else if (di->cache.flags & BQ27500_FLAG_DSC)
 			status = POWER_SUPPLY_STATUS_DISCHARGING;
 		else
 			status = POWER_SUPPLY_STATUS_CHARGING;
 	} else {
-		if (flags & BQ27000_FLAG_CHGS)
+		if (di->cache.flags & BQ27000_FLAG_FC)
+			status = POWER_SUPPLY_STATUS_FULL;
+		else if (di->cache.flags & BQ27000_FLAG_CHGS)
 			status = POWER_SUPPLY_STATUS_CHARGING;
+		else if (power_supply_am_i_supplied(&di->bat))
+			status = POWER_SUPPLY_STATUS_NOT_CHARGING;
 		else
 			status = POWER_SUPPLY_STATUS_DISCHARGING;
 	}
 
 	val->intval = status;
+
 	return 0;
 }
 
 /*
- * Read a time register.
- * Return < 0 if something fails.
+ * Return the battery Voltage in milivolts
+ * Or < 0 if something fails.
  */
-static int bq27x00_battery_time(struct bq27x00_device_info *di, int reg,
-				union power_supply_propval *val)
+static int bq27x00_battery_voltage(struct bq27x00_device_info *di,
+	union power_supply_propval *val)
 {
-	int tval = 0;
-	int ret;
+	int volt;
 
-	ret = bq27x00_read(reg, &tval, 0, di);
-	if (ret) {
-		dev_err(di->dev, "error reading register %02x\n", reg);
-		return ret;
+	volt = bq27x00_read(di, BQ27x00_REG_VOLT, false);
+	if (volt < 0)
+		return volt;
+
+	val->intval = volt * 1000;
+
+	return 0;
+}
+
+/*
+ * Return the battery Available energy in µWh
+ * Or < 0 if something fails.
+ */
+static int bq27x00_battery_energy(struct bq27x00_device_info *di,
+	union power_supply_propval *val)
+{
+	int ae;
+
+	ae = bq27x00_read(di, BQ27x00_REG_AE, false);
+	if (ae < 0) {
+		dev_err(di->dev, "error reading available energy\n");
+		return ae;
 	}
 
-	if (tval == 65535)
-		return -ENODATA;
+	if (di->chip == BQ27500)
+		ae *= 1000;
+	else
+		ae = ae * 29200 / BQ27000_RS;
+
+	val->intval = ae;
+
+	return 0;
+}
+
+
+static int bq27x00_simple_value(int value,
+	union power_supply_propval *val)
+{
+	if (value < 0)
+		return value;
+
+	val->intval = value;
 
-	val->intval = tval * 60;
 	return 0;
 }
 
@@ -249,33 +446,61 @@ static int bq27x00_battery_get_property(struct power_supply *psy,
 	int ret = 0;
 	struct bq27x00_device_info *di = to_bq27x00_device_info(psy);
 
+	mutex_lock(&di->lock);
+	if (time_is_before_jiffies(di->last_update + 5 * HZ)) {
+		cancel_delayed_work_sync(&di->work);
+		bq27x00_battery_poll(&di->work.work);
+	}
+	mutex_unlock(&di->lock);
+
+	if (psp != POWER_SUPPLY_PROP_PRESENT && di->cache.flags < 0)
+		return -ENODEV;
+
 	switch (psp) {
 	case POWER_SUPPLY_PROP_STATUS:
 		ret = bq27x00_battery_status(di, val);
 		break;
 	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = bq27x00_battery_voltage(di, val);
+		break;
 	case POWER_SUPPLY_PROP_PRESENT:
-		val->intval = bq27x00_battery_voltage(di);
-		if (psp == POWER_SUPPLY_PROP_PRESENT)
-			val->intval = val->intval <= 0 ? 0 : 1;
+		val->intval = di->cache.flags < 0 ? 0 : 1;
 		break;
 	case POWER_SUPPLY_PROP_CURRENT_NOW:
-		val->intval = bq27x00_battery_current(di);
+		ret = bq27x00_battery_current(di, val);
 		break;
 	case POWER_SUPPLY_PROP_CAPACITY:
-		val->intval = bq27x00_battery_rsoc(di);
+		ret = bq27x00_simple_value(di->cache.capacity, val);
 		break;
 	case POWER_SUPPLY_PROP_TEMP:
-		val->intval = bq27x00_battery_temperature(di);
+		ret = bq27x00_battery_temperature(di, val);
 		break;
 	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
-		ret = bq27x00_battery_time(di, BQ27x00_REG_TTE, val);
+		ret = bq27x00_simple_value(di->cache.time_to_empty, val);
 		break;
 	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
-		ret = bq27x00_battery_time(di, BQ27x00_REG_TTECP, val);
+		ret = bq27x00_simple_value(di->cache.time_to_empty_avg, val);
 		break;
 	case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
-		ret = bq27x00_battery_time(di, BQ27x00_REG_TTF, val);
+		ret = bq27x00_simple_value(di->cache.time_to_full, val);
+		break;
+	case POWER_SUPPLY_PROP_TECHNOLOGY:
+		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		ret = bq27x00_simple_value(bq27x00_battery_read_nac(di), val);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL:
+		ret = bq27x00_simple_value(di->cache.charge_full, val);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		ret = bq27x00_simple_value(di->charge_design_full, val);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
+		ret = bq27x00_simple_value(di->cache.charge_counter, val);
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_NOW:
+		ret = bq27x00_battery_energy(di, val);
 		break;
 	default:
 		return -EINVAL;
@@ -284,56 +509,91 @@ static int bq27x00_battery_get_property(struct power_supply *psy,
 	return ret;
 }
 
-static void bq27x00_powersupply_init(struct bq27x00_device_info *di)
+static void bq27x00_external_power_changed(struct power_supply *psy)
 {
+	struct bq27x00_device_info *di = to_bq27x00_device_info(psy);
+
+	cancel_delayed_work_sync(&di->work);
+	schedule_delayed_work(&di->work, 0);
+}
+
+static int bq27x00_powersupply_init(struct bq27x00_device_info *di)
+{
+	int ret;
+
 	di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
 	di->bat.properties = bq27x00_battery_props;
 	di->bat.num_properties = ARRAY_SIZE(bq27x00_battery_props);
 	di->bat.get_property = bq27x00_battery_get_property;
-	di->bat.external_power_changed = NULL;
+	di->bat.external_power_changed = bq27x00_external_power_changed;
+
+	INIT_DELAYED_WORK(&di->work, bq27x00_battery_poll);
+	mutex_init(&di->lock);
+
+	ret = power_supply_register(di->dev, &di->bat);
+	if (ret) {
+		dev_err(di->dev, "failed to register battery: %d\n", ret);
+		return ret;
+	}
+
+	dev_info(di->dev, "support ver. %s enabled\n", DRIVER_VERSION);
+
+	bq27x00_update(di);
+
+	return 0;
 }
 
-/*
- * i2c specific code
+static void bq27x00_powersupply_unregister(struct bq27x00_device_info *di)
+{
+	cancel_delayed_work_sync(&di->work);
+
+	power_supply_unregister(&di->bat);
+
+	mutex_destroy(&di->lock);
+}
+
+
+/* i2c specific code */
+#ifdef CONFIG_BATTERY_BQ27X00_I2C
+
+/* If the system has several batteries we need a different name for each
+ * of them...
  */
+static DEFINE_IDR(battery_id);
+static DEFINE_MUTEX(battery_mutex);
 
-static int bq27x00_read_i2c(u8 reg, int *rt_value, int b_single,
-			struct bq27x00_device_info *di)
+static int bq27x00_read_i2c(struct bq27x00_device_info *di, u8 reg, bool single)
 {
-	struct i2c_client *client = di->client;
-	struct i2c_msg msg[1];
+	struct i2c_client *client = to_i2c_client(di->dev);
+	struct i2c_msg msg[2];
 	unsigned char data[2];
-	int err;
+	int ret;
 
 	if (!client->adapter)
 		return -ENODEV;
 
-	msg->addr = client->addr;
-	msg->flags = 0;
-	msg->len = 1;
-	msg->buf = data;
-
-	data[0] = reg;
-	err = i2c_transfer(client->adapter, msg, 1);
+	msg[0].addr = client->addr;
+	msg[0].flags = 0;
+	msg[0].buf = &reg;
+	msg[0].len = sizeof(reg);
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].buf = data;
+	if (single)
+		msg[1].len = 1;
+	else
+		msg[1].len = 2;
 
-	if (err >= 0) {
-		if (!b_single)
-			msg->len = 2;
-		else
-			msg->len = 1;
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret < 0)
+		return ret;
 
-		msg->flags = I2C_M_RD;
-		err = i2c_transfer(client->adapter, msg, 1);
-		if (err >= 0) {
-			if (!b_single)
-				*rt_value = get_unaligned_le16(data);
-			else
-				*rt_value = data[0];
+	if (!single)
+		ret = get_unaligned_le16(data);
+	else
+		ret = data[0];
 
-			return 0;
-		}
-	}
-	return err;
+	return ret;
 }
 
 static int bq27x00_battery_probe(struct i2c_client *client,
@@ -341,7 +601,6 @@ static int bq27x00_battery_probe(struct i2c_client *client,
 {
 	char *name;
 	struct bq27x00_device_info *di;
-	struct bq27x00_access_methods *bus;
 	int num;
 	int retval = 0;
 
@@ -368,38 +627,20 @@ static int bq27x00_battery_probe(struct i2c_client *client,
 		retval = -ENOMEM;
 		goto batt_failed_2;
 	}
+
 	di->id = num;
+	di->dev = &client->dev;
 	di->chip = id->driver_data;
+	di->bat.name = name;
+	di->bus.read = &bq27x00_read_i2c;
 
-	bus = kzalloc(sizeof(*bus), GFP_KERNEL);
-	if (!bus) {
-		dev_err(&client->dev, "failed to allocate access method "
-					"data\n");
-		retval = -ENOMEM;
+	if (bq27x00_powersupply_init(di))
 		goto batt_failed_3;
-	}
 
 	i2c_set_clientdata(client, di);
-	di->dev = &client->dev;
-	di->bat.name = name;
-	bus->read = &bq27x00_read_i2c;
-	di->bus = bus;
-	di->client = client;
-
-	bq27x00_powersupply_init(di);
-
-	retval = power_supply_register(&client->dev, &di->bat);
-	if (retval) {
-		dev_err(&client->dev, "failed to register battery\n");
-		goto batt_failed_4;
-	}
-
-	dev_info(&client->dev, "support ver. %s enabled\n", DRIVER_VERSION);
 
 	return 0;
 
-batt_failed_4:
-	kfree(bus);
 batt_failed_3:
 	kfree(di);
 batt_failed_2:
@@ -416,9 +657,8 @@ static int bq27x00_battery_remove(struct i2c_client *client)
 {
 	struct bq27x00_device_info *di = i2c_get_clientdata(client);
 
-	power_supply_unregister(&di->bat);
+	bq27x00_powersupply_unregister(di);
 
-	kfree(di->bus);
 	kfree(di->bat.name);
 
 	mutex_lock(&battery_mutex);
@@ -430,15 +670,12 @@ static int bq27x00_battery_remove(struct i2c_client *client)
 	return 0;
 }
 
-/*
- * Module stuff
- */
-
 static const struct i2c_device_id bq27x00_id[] = {
 	{ "bq27200", BQ27000 },	/* bq27200 is same as bq27000, but with i2c */
 	{ "bq27500", BQ27500 },
 	{},
 };
+MODULE_DEVICE_TABLE(i2c, bq27x00_id);
 
 static struct i2c_driver bq27x00_battery_driver = {
 	.driver = {
@@ -449,13 +686,164 @@ static struct i2c_driver bq27x00_battery_driver = {
 	.id_table = bq27x00_id,
 };
 
+static inline int bq27x00_battery_i2c_init(void)
+{
+	int ret = i2c_add_driver(&bq27x00_battery_driver);
+	if (ret)
+		printk(KERN_ERR "Unable to register BQ27x00 i2c driver\n");
+
+	return ret;
+}
+
+static inline void bq27x00_battery_i2c_exit(void)
+{
+	i2c_del_driver(&bq27x00_battery_driver);
+}
+
+#else
+
+static inline int bq27x00_battery_i2c_init(void) { return 0; }
+static inline void bq27x00_battery_i2c_exit(void) {};
+
+#endif
+
+/* platform specific code */
+#ifdef CONFIG_BATTERY_BQ27X00_PLATFORM
+
+static int bq27000_read_platform(struct bq27x00_device_info *di, u8 reg,
+			bool single)
+{
+	struct device *dev = di->dev;
+	struct bq27000_platform_data *pdata = dev->platform_data;
+	unsigned int timeout = 3;
+	int upper, lower;
+	int temp;
+
+	if (!single) {
+		/* Make sure the value has not changed in between reading the
+		 * lower and the upper part */
+		upper = pdata->read(dev, reg + 1);
+		do {
+			temp = upper;
+			if (upper < 0)
+				return upper;
+
+			lower = pdata->read(dev, reg);
+			if (lower < 0)
+				return lower;
+
+			upper = pdata->read(dev, reg + 1);
+		} while (temp != upper && --timeout);
+
+		if (timeout == 0)
+			return -EIO;
+
+		return (upper << 8) | lower;
+	}
+
+	return pdata->read(dev, reg);
+}
+
+static int __devinit bq27000_battery_probe(struct platform_device *pdev)
+{
+	struct bq27x00_device_info *di;
+	struct bq27000_platform_data *pdata = pdev->dev.platform_data;
+	int ret;
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "no platform_data supplied\n");
+		return -EINVAL;
+	}
+
+	if (!pdata->read) {
+		dev_err(&pdev->dev, "no hdq read callback supplied\n");
+		return -EINVAL;
+	}
+
+	di = kzalloc(sizeof(*di), GFP_KERNEL);
+	if (!di) {
+		dev_err(&pdev->dev, "failed to allocate device info data\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, di);
+
+	di->dev = &pdev->dev;
+	di->chip = BQ27000;
+
+	di->bat.name = pdata->name ?: dev_name(&pdev->dev);
+	di->bus.read = &bq27000_read_platform;
+
+	ret = bq27x00_powersupply_init(di);
+	if (ret)
+		goto err_free;
+
+	return 0;
+
+err_free:
+	platform_set_drvdata(pdev, NULL);
+	kfree(di);
+
+	return ret;
+}
+
+static int __devexit bq27000_battery_remove(struct platform_device *pdev)
+{
+	struct bq27x00_device_info *di = platform_get_drvdata(pdev);
+
+	bq27x00_powersupply_unregister(di);
+
+	platform_set_drvdata(pdev, NULL);
+	kfree(di);
+
+	return 0;
+}
+
+static struct platform_driver bq27000_battery_driver = {
+	.probe	= bq27000_battery_probe,
+	.remove = __devexit_p(bq27000_battery_remove),
+	.driver = {
+		.name = "bq27000-battery",
+		.owner = THIS_MODULE,
+	},
+};
+
+static inline int bq27x00_battery_platform_init(void)
+{
+	int ret = platform_driver_register(&bq27000_battery_driver);
+	if (ret)
+		printk(KERN_ERR "Unable to register BQ27000 platform driver\n");
+
+	return ret;
+}
+
+static inline void bq27x00_battery_platform_exit(void)
+{
+	platform_driver_unregister(&bq27000_battery_driver);
+}
+
+#else
+
+static inline int bq27x00_battery_platform_init(void) { return 0; }
+static inline void bq27x00_battery_platform_exit(void) {};
+
+#endif
+
+/*
+ * Module stuff
+ */
+
 static int __init bq27x00_battery_init(void)
 {
 	int ret;
 
-	ret = i2c_add_driver(&bq27x00_battery_driver);
+	ret = bq27x00_battery_i2c_init();
 	if (ret)
-		printk(KERN_ERR "Unable to register BQ27x00 driver\n");
+		return ret;
+
+	ret = bq27x00_battery_platform_init();
+	if (ret)
+		bq27x00_battery_i2c_exit();
 
 	return ret;
 }
@@ -463,7 +851,8 @@ module_init(bq27x00_battery_init);
 
 static void __exit bq27x00_battery_exit(void)
 {
-	i2c_del_driver(&bq27x00_battery_driver);
+	bq27x00_battery_platform_exit();
+	bq27x00_battery_i2c_exit();
 }
 module_exit(bq27x00_battery_exit);
 
diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index 970f7335d3a7..329b46b2327d 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -171,6 +171,8 @@ int power_supply_register(struct device *parent, struct power_supply *psy)
 	dev_set_drvdata(dev, psy);
 	psy->dev = dev;
 
+	INIT_WORK(&psy->changed_work, power_supply_changed_work);
+
 	rc = kobject_set_name(&dev->kobj, "%s", psy->name);
 	if (rc)
 		goto kobject_set_name_failed;
@@ -179,8 +181,6 @@ int power_supply_register(struct device *parent, struct power_supply *psy)
 	if (rc)
 		goto device_add_failed;
 
-	INIT_WORK(&psy->changed_work, power_supply_changed_work);
-
 	rc = power_supply_create_triggers(psy);
 	if (rc)
 		goto create_triggers_failed;
diff --git a/drivers/power/power_supply_sysfs.c b/drivers/power/power_supply_sysfs.c
index cd1f90754a3a..605514afc29f 100644
--- a/drivers/power/power_supply_sysfs.c
+++ b/drivers/power/power_supply_sysfs.c
@@ -270,7 +270,7 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
 		attr = &power_supply_attrs[psy->properties[j]];
 
 		ret = power_supply_show_property(dev, attr, prop_buf);
-		if (ret == -ENODEV) {
+		if (ret == -ENODEV || ret == -ENODATA) {
 			/* When a battery is absent, we expect -ENODEV. Don't abort;
 			   send the uevent with at least the the PRESENT=0 property */
 			ret = 0;
diff --git a/include/linux/power/bq27x00_battery.h b/include/linux/power/bq27x00_battery.h
new file mode 100644
index 000000000000..a857f719bf40
--- /dev/null
+++ b/include/linux/power/bq27x00_battery.h
@@ -0,0 +1,19 @@
+#ifndef __LINUX_BQ27X00_BATTERY_H__
+#define __LINUX_BQ27X00_BATTERY_H__
+
+/**
+ * struct bq27000_plaform_data - Platform data for bq27000 devices
+ * @name: Name of the battery. If NULL the driver will fallback to "bq27000".
+ * @read: HDQ read callback.
+ *	This function should provide access to the HDQ bus the battery is
+ *	connected to.
+ *	The first parameter is a pointer to the battery device, the second the
+ *	register to be read. The return value should either be the content of
+ *	the passed register or an error value.
+ */
+struct bq27000_platform_data {
+	const char *name;
+	int (*read)(struct device *dev, unsigned int);
+};
+
+#endif