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