Re: [PATCH v3] w1: Add Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC support.

Re: [PATCH v3] w1: Add Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC support.

[Simon INIZAN]

On 31/05/2011 14:42, Barnes, Clifton A. wrote:
> On Monday, May 30, 2011, Simon INIZAN wrote:
>
>> However from time to time I a getting stuck in the driver.
> Getting stuck meaning a deadlock?  Is it during a read on a
> sysfs file?  Are you using the driver compiled in or as a
> module?
I have tested the driver with the fix you provided me, I am not getting 
a deadlock anymore.

>> FYI, I am using the GPIO 1-wire driver, and from time to time the gauge is not responding to the w1 queries.
> Is this the same condition you're talking about above?  Does this mean that sometimes
> the sysfs file returns and sometimes it hangs?
>
It seems I am getting some flipped bits on the 1-wire bus (using the 
w1-gpio master),
this is not directly related to your driver but it makes the results not 
very reliable
on my platform (sometimes the rsgain is wrong, so are the currents).
I am getting a 1-wire bus analyzer to investigate the issue.



In the get_current function, you are returning:

sense_res = 1000 / sense_res_raw;
*current_uA = current_raw * (DS2780_CURRENT_UNITS / sense_res);


Which means that we are getting current (in µA) = current_raw (in 
µV/Ohms) * sense_res_raw (in Ohms).
I have replaced it with

sense_res = sense_res_raw;
*current_uA = current_raw * (DS2780_CURRENT_UNITS / sense_res);


Which gives me more consistent results with my measures.

Simon

Re: [PATCH v3] w1: Add Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC support.

[Ryan Mallon]

On 05/20/2011 12:21 AM, Clifton Barnes wrote:
> Add support for the Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC.
> 
> I've updated the driver based on feedback from the last version.
> I believe the locking is correct because the w1_ds2780_io function
> has locking in it.  If there's still a problem that I'm missing let 
> me know and I can correct it.
> 
> Changes for v3:
>  - Formatting changes suggested from last version
>  - Moved read/write functions to battery driver
>  - Corrected temperature calculation
>  - Changed EEPROM access to bin_attribute
> 
> Signed-off-by: Clifton Barnes <cabarnes@indesign-llc.com>

Hi Clifton,

Looks much better. I have a few minor comments below (feel free to
ignore them since its all style stuff), but otherwise looks fine.

Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>

> ---
>  drivers/power/Kconfig          |    7 +
>  drivers/power/Makefile         |    1 +
>  drivers/power/ds2780_battery.c |  853 ++++++++++++++++++++++++++++++++++++++++
>  drivers/w1/slaves/Kconfig      |   13 +
>  drivers/w1/slaves/Makefile     |    1 +
>  drivers/w1/slaves/w1_ds2780.c  |  217 ++++++++++
>  drivers/w1/slaves/w1_ds2780.h  |  129 ++++++
>  drivers/w1/w1_family.h         |    1 +
>  8 files changed, 1222 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/power/ds2780_battery.c
>  create mode 100644 drivers/w1/slaves/w1_ds2780.c
>  create mode 100644 drivers/w1/slaves/w1_ds2780.h
> 
> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
> index 52a462f..dc8c531 100644
> --- a/drivers/power/Kconfig
> +++ b/drivers/power/Kconfig
> @@ -68,6 +68,13 @@ config BATTERY_DS2760
>  	help
>  	  Say Y here to enable support for batteries with ds2760 chip.
>  
> +config BATTERY_DS2780
> +	tristate "DS2780 battery driver"
> +	select W1
> +	select W1_SLAVE_DS2780
> +	help
> +	  Say Y here to enable support for batteries with ds2780 chip.
> +
>  config BATTERY_DS2782
>  	tristate "DS2782/DS2786 standalone gas-gauge"
>  	depends on I2C
> diff --git a/drivers/power/Makefile b/drivers/power/Makefile
> index 8385bfa..8224990 100644
> --- a/drivers/power/Makefile
> +++ b/drivers/power/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_WM8350_POWER)	+= wm8350_power.o
>  obj-$(CONFIG_TEST_POWER)	+= test_power.o
>  
>  obj-$(CONFIG_BATTERY_DS2760)	+= ds2760_battery.o
> +obj-$(CONFIG_BATTERY_DS2780)	+= ds2780_battery.o
>  obj-$(CONFIG_BATTERY_DS2782)	+= ds2782_battery.o
>  obj-$(CONFIG_BATTERY_PMU)	+= pmu_battery.o
>  obj-$(CONFIG_BATTERY_OLPC)	+= olpc_battery.o
> diff --git a/drivers/power/ds2780_battery.c b/drivers/power/ds2780_battery.c
> new file mode 100644
> index 0000000..55362dd
> --- /dev/null
> +++ b/drivers/power/ds2780_battery.c
> @@ -0,0 +1,853 @@
> +/*
> + * 1-wire client/driver for the Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC
> + *
> + * Copyright (C) 2010 Indesign, LLC
> + *
> + * Author: Clifton Barnes <cabarnes@indesign-llc.com>
> + *
> + * Based on ds2760_battery and ds2782_battery drivers
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/param.h>
> +#include <linux/pm.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/idr.h>
> +
> +#include "../w1/w1.h"
> +#include "../w1/slaves/w1_ds2780.h"
> +
> +/* Current unit measurement in uA for a 1 milli-ohm sense resistor */
> +#define DS2780_CURRENT_UNITS	1563
> +/* Charge unit measurement in uAh for a 1 milli-ohm sense resistor */
> +#define DS2780_CHARGE_UNITS		6250
> +/* Number of bytes in user EEPROM space */
> +#define DS2780_USER_EEPROM_SIZE		(DS2780_EEPROM_BLOCK0_END - \
> +					DS2780_EEPROM_BLOCK0_START + 1)
> +/* Number of bytes in parameter EEPROM space */
> +#define DS2780_PARAM_EEPROM_SIZE	(DS2780_EEPROM_BLOCK1_END - \
> +					DS2780_EEPROM_BLOCK1_START + 1)
> +
> +struct ds2780_device_info {
> +	struct device *dev;
> +	struct power_supply bat;
> +	struct device *w1_dev;
> +};
> +
> +enum current_types {
> +	CURRENT_NOW,
> +	CURRENT_AVG,
> +};
> +
> +static const char model[] = "DS2780";
> +static const char manufacturer[] = "Maxim/Dallas";
> +
> +static inline struct ds2780_device_info *to_ds2780_device_info(
> +	struct power_supply *psy)

Split lines like this commonly get written like this:

static inline struct ds2780_device_info *
to_ds2780_device_info(struct power_supply *psy)

> +{
> +	return container_of(psy, struct ds2780_device_info, bat);
> +}
> +
> +static inline struct power_supply *to_power_supply(struct device *dev)
> +{
> +	return dev_get_drvdata(dev);
> +}
> +
> +static inline int ds2780_read8(struct device *dev, u8 *val, int addr)
> +{
> +	return w1_ds2780_io(dev, val, addr, sizeof(u8), 0);
> +}
> +
> +static int ds2780_read16(struct device *dev, s16 *val, int addr)
> +{
> +	int ret;
> +	u8 raw[2];
> +
> +	ret = w1_ds2780_io(dev, raw, addr, sizeof(u8) * 2, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = (raw[0] << 8) | raw[1];
> +
> +	return 0;
> +}
> +
> +static inline int ds2780_read_block(struct device *dev, u8 *val, int addr,
> +	size_t count)
> +{
> +	return w1_ds2780_io(dev, val, addr, count, 0);
> +}
> +
> +static inline int ds2780_write(struct device *dev, u8 *val, int addr,
> +	size_t count)
> +{
> +	return w1_ds2780_io(dev, val, addr, count, 1);
> +}
> +
> +static inline int ds2780_store_eeprom(struct device *dev, int addr)
> +{
> +	return w1_ds2780_eeprom_cmd(dev, addr, W1_DS2780_COPY_DATA);
> +}
> +
> +static inline int ds2780_recall_eeprom(struct device *dev, int addr)
> +{
> +	return w1_ds2780_eeprom_cmd(dev, addr, W1_DS2780_RECALL_DATA);
> +}
> +
> +static int ds2780_save_eeprom(struct ds2780_device_info *dev_info, int reg)
> +{
> +	int ret;
> +
> +	ret = ds2780_store_eeprom(dev_info->w1_dev, reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ds2780_recall_eeprom(dev_info->w1_dev, reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +/* Set sense resistor value in mhos */
> +static int ds2780_set_sense_register(struct ds2780_device_info *dev_info,
> +	u8 conductance)
> +{
> +	int ret;
> +
> +	ret = ds2780_write(dev_info->w1_dev, &conductance,
> +				DS2780_RSNSP_REG, sizeof(u8));
> +	if (ret < 0)
> +		return ret;
> +
> +	return ds2780_save_eeprom(dev_info, DS2780_RSNSP_REG);
> +}
> +
> +/* Get RSGAIN value from 0 to 1.999 in steps of 0.001 */
> +static int ds2780_get_rsgain_register(struct ds2780_device_info *dev_info,
> +	u16 *rsgain)
> +{
> +	return ds2780_read16(dev_info->w1_dev, rsgain, DS2780_RSGAIN_MSB_REG);
> +}
> +
> +/* Set RSGAIN value from 0 to 1.999 in steps of 0.001 */
> +static int ds2780_set_rsgain_register(struct ds2780_device_info *dev_info,
> +	u16 rsgain)
> +{
> +	int ret;
> +	u8 raw[] = {rsgain >> 8, rsgain & 0xFF};
> +
> +	ret = ds2780_write(dev_info->w1_dev, raw,
> +				DS2780_RSGAIN_MSB_REG, sizeof(u8) * 2);

You could use sizeof(raw) here.

> +	if (ret < 0)
> +		return ret;
> +
> +	return ds2780_save_eeprom(dev_info, DS2780_RSGAIN_MSB_REG);
> +}
> +
> +static int ds2780_get_voltage(struct ds2780_device_info *dev_info,
> +	int *voltage_uV)
> +{
> +	int ret;
> +	s16 voltage_raw;
> +
> +	/*
> +	 * The voltage value is located in 10 bits across the voltage MSB
> +	 * and LSB registers in two's compliment form
> +	 * Sign bit of the voltage value is in bit 7 of the voltage MSB register
> +	 * Bits 9 - 3 of the voltage value are in bits 6 - 0 of the
> +	 * voltage MSB register
> +	 * Bits 2 - 0 of the voltage value are in bits 7 - 5 of the
> +	 * voltage LSB register
> +	 */
> +	ret = ds2780_read16(dev_info->w1_dev, &voltage_raw,
> +				DS2780_VOLT_MSB_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * DS2780 reports voltage in units of 4.88mV, but the battery class
> +	 * reports in units of uV, so convert by multiplying by 4880.
> +	 */
> +	*voltage_uV = (voltage_raw / 32) * 4880;
> +	return 0;
> +}
> +
> +static int ds2780_get_temperature(struct ds2780_device_info *dev_info,
> +	int *temperature)
> +{
> +	int ret;
> +	s16 temperature_raw;
> +
> +	/*
> +	 * The temperature value is located in 10 bits across the temperature
> +	 * MSB and LSB registers in two's compliment form
> +	 * Sign bit of the temperature value is in bit 7 of the temperature
> +	 * MSB register
> +	 * Bits 9 - 3 of the temperature value are in bits 6 - 0 of the
> +	 * temperature MSB register
> +	 * Bits 2 - 0 of the temperature value are in bits 7 - 5 of the
> +	 * temperature LSB register
> +	 */
> +	ret = ds2780_read16(dev_info->w1_dev, &temperature_raw,
> +				DS2780_TEMP_MSB_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Temperature is measured in units of 0.125 degrees celcius, the
> +	 * power_supply class measures temperature in tenths of degrees
> +	 * celsius. The temperature value is stored as a 10 bit number, plus
> +	 * sign in the upper bits of a 16 bit register.
> +	 */
> +	*temperature = ((temperature_raw / 32) * 125) / 100;
> +	return 0;
> +}
> +
> +static int ds2780_get_current(struct ds2780_device_info *dev_info,
> +	enum current_types type, int *current_uA)
> +{
> +	int ret, sense_res;
> +	s16 current_raw;
> +	u8 sense_res_raw, reg_msb;
> +
> +	/*
> +	 * The units of measurement for current are dependent on the value of
> +	 * the sense resistor.
> +	 */
> +	ret = ds2780_read8(dev_info->w1_dev, &sense_res_raw, DS2780_RSNSP_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (sense_res_raw == 0) {
> +		dev_err(dev_info->dev, "sense resistor value is 0\n");
> +		return -ENXIO;

Maybe EINVAL?

> +	}
> +	sense_res = 1000 / sense_res_raw;
> +
> +	if (type == CURRENT_NOW)
> +		reg_msb = DS2780_CURRENT_MSB_REG;
> +	else if (type == CURRENT_AVG)
> +		reg_msb = DS2780_IAVG_MSB_REG;
> +	else
> +		return -EINVAL;
> +
> +	/*
> +	 * The current value is located in 16 bits across the current MSB
> +	 * and LSB registers in two's compliment form
> +	 * Sign bit of the current value is in bit 7 of the current MSB register
> +	 * Bits 14 - 8 of the current value are in bits 6 - 0 of the current
> +	 * MSB register
> +	 * Bits 7 - 0 of the current value are in bits 7 - 0 of the current
> +	 * LSB register
> +	 */
> +	ret = ds2780_read16(dev_info->w1_dev, &current_raw, reg_msb);
> +	if (ret < 0)
> +		return ret;
> +
> +	*current_uA = current_raw * (DS2780_CURRENT_UNITS / sense_res);
> +	return 0;
> +}
> +
> +static int ds2780_get_accumulated_current(struct ds2780_device_info *dev_info,
> +	int *accumulated_current)
> +{
> +	int ret, sense_res;
> +	s16 current_raw;
> +	u8 sense_res_raw;
> +
> +	/*
> +	 * The units of measurement for accumulated current are dependent on
> +	 * the value of the sense resistor.
> +	 */
> +	ret = ds2780_read8(dev_info->w1_dev, &sense_res_raw, DS2780_RSNSP_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (sense_res_raw == 0) {
> +		dev_err(dev_info->dev, "sense resistor value is 0\n");
> +		return -ENXIO;
> +	}
> +	sense_res = 1000 / sense_res_raw;
> +
> +	/*
> +	 * The ACR value is located in 16 bits across the ACR MSB and
> +	 * LSB registers
> +	 * Bits 15 - 8 of the ACR value are in bits 7 - 0 of the ACR
> +	 * MSB register
> +	 * Bits 7 - 0 of the ACR value are in bits 7 - 0 of the ACR
> +	 * LSB register
> +	 */
> +	ret = ds2780_read16(dev_info->w1_dev, &current_raw, DS2780_ACR_MSB_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	*accumulated_current = current_raw * (DS2780_CHARGE_UNITS / sense_res);
> +	return 0;
> +}
> +
> +static int ds2780_get_capacity(struct ds2780_device_info *dev_info,
> +	int *capacity)
> +{
> +	int ret;
> +	u8 raw;
> +
> +	ret = ds2780_read8(dev_info->w1_dev, &raw, DS2780_RARC_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	*capacity = raw;
> +	return raw;
> +}
> +
> +static int ds2780_get_status(struct ds2780_device_info *dev_info, int *status)
> +{
> +	int ret, current_uA, capacity;
> +
> +	ret = ds2780_get_current(dev_info, CURRENT_NOW, &current_uA);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ds2780_get_capacity(dev_info, &capacity);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (capacity == 100)
> +		*status = POWER_SUPPLY_STATUS_FULL;
> +	else if (current_uA == 0)
> +		*status = POWER_SUPPLY_STATUS_NOT_CHARGING;
> +	else if (current_uA < 0)
> +		*status = POWER_SUPPLY_STATUS_DISCHARGING;
> +	else
> +		*status = POWER_SUPPLY_STATUS_CHARGING;
> +
> +	return 0;
> +}
> +
> +static int ds2780_get_charge_now(struct ds2780_device_info *dev_info,
> +	int *charge_now)
> +{
> +	int ret;
> +	u16 charge_raw;
> +
> +	/*
> +	 * The RAAC value is located in 16 bits across the RAAC MSB and
> +	 * LSB registers
> +	 * Bits 15 - 8 of the RAAC value are in bits 7 - 0 of the RAAC
> +	 * MSB register
> +	 * Bits 7 - 0 of the RAAC value are in bits 7 - 0 of the RAAC
> +	 * LSB register
> +	 */
> +	ret = ds2780_read16(dev_info->w1_dev, &charge_raw, DS2780_RAAC_MSB_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	*charge_now = charge_raw * 1600;
> +	return 0;
> +}
> +
> +static int ds2780_get_control_register(struct ds2780_device_info *dev_info,
> +	u8 *control_reg)
> +{
> +	return ds2780_read8(dev_info->w1_dev, control_reg, DS2780_CONTROL_REG);
> +}
> +
> +static int ds2780_set_control_register(struct ds2780_device_info *dev_info,
> +	u8 control_reg)
> +{
> +	int ret;
> +
> +	ret = ds2780_write(dev_info->w1_dev, &control_reg,
> +				DS2780_CONTROL_REG, sizeof(u8));
> +	if (ret < 0)
> +		return ret;
> +
> +	return ds2780_save_eeprom(dev_info, DS2780_CONTROL_REG);
> +}
> +
> +static int ds2780_battery_get_property(struct power_supply *psy,
> +	enum power_supply_property psp,
> +	union power_supply_propval *val)
> +{
> +	int ret = 0;
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> +		ret = ds2780_get_voltage(dev_info, &val->intval);
> +		break;
> +
> +	case POWER_SUPPLY_PROP_TEMP:
> +		ret = ds2780_get_temperature(dev_info, &val->intval);
> +		break;
> +
> +	case POWER_SUPPLY_PROP_MODEL_NAME:
> +		val->strval = model;
> +		break;
> +
> +	case POWER_SUPPLY_PROP_MANUFACTURER:
> +		val->strval = manufacturer;
> +		break;
> +
> +	case POWER_SUPPLY_PROP_CURRENT_NOW:
> +		ret = ds2780_get_current(dev_info, CURRENT_NOW, &val->intval);
> +		break;
> +
> +	case POWER_SUPPLY_PROP_CURRENT_AVG:
> +		ret = ds2780_get_current(dev_info, CURRENT_AVG, &val->intval);
> +		break;
> +
> +	case POWER_SUPPLY_PROP_STATUS:
> +		ret = ds2780_get_status(dev_info, &val->intval);
> +		break;
> +
> +	case POWER_SUPPLY_PROP_CAPACITY:
> +		ret = ds2780_get_capacity(dev_info, &val->intval);
> +		break;
> +
> +	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
> +		ret = ds2780_get_accumulated_current(dev_info, &val->intval);
> +		break;
> +
> +	case POWER_SUPPLY_PROP_CHARGE_NOW:
> +		ret = ds2780_get_charge_now(dev_info, &val->intval);
> +		break;
> +
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static enum power_supply_property ds2780_battery_props[] = {
> +	POWER_SUPPLY_PROP_STATUS,
> +	POWER_SUPPLY_PROP_VOLTAGE_NOW,
> +	POWER_SUPPLY_PROP_TEMP,
> +	POWER_SUPPLY_PROP_MODEL_NAME,
> +	POWER_SUPPLY_PROP_MANUFACTURER,
> +	POWER_SUPPLY_PROP_CURRENT_NOW,
> +	POWER_SUPPLY_PROP_CURRENT_AVG,
> +	POWER_SUPPLY_PROP_CAPACITY,
> +	POWER_SUPPLY_PROP_CHARGE_COUNTER,
> +	POWER_SUPPLY_PROP_CHARGE_NOW,
> +};
> +
> +static ssize_t ds2780_get_pmod_enabled(struct device *dev,
> +	struct device_attribute *attr,
> +	char *buf)
> +{
> +	int ret;
> +	u8 control_reg;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	/* Get power mode */
> +	ret = ds2780_get_control_register(dev_info, &control_reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	return sprintf(buf, "%d\n",
> +		 !!(control_reg & DS2780_CONTROL_REG_PMOD));
> +}
> +
> +static ssize_t ds2780_set_pmod_enabled(struct device *dev,
> +	struct device_attribute *attr,
> +	const char *buf,
> +	size_t count)
> +{
> +	int ret;
> +	u8 control_reg, new_setting;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	/* Set power mode */
> +	ret = ds2780_get_control_register(dev_info, &control_reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = kstrtou8(buf, 0, &new_setting);
> +	if (ret < 0)
> +		return ret;
> +
> +	if ((new_setting != 0) && (new_setting != 1)) {
> +		dev_err(dev_info->dev, "Invalid pmod setting (0 or 1)\n");
> +		return -EINVAL;
> +	}
> +
> +	if (new_setting)
> +		control_reg |= DS2780_CONTROL_REG_PMOD;
> +	else
> +		control_reg &= ~DS2780_CONTROL_REG_PMOD;
> +
> +	ret = ds2780_set_control_register(dev_info, control_reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t ds2780_get_sense_resistor_value(struct device *dev,
> +	struct device_attribute *attr,
> +	char *buf)
> +{
> +	int ret;
> +	u8 sense_resistor;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	ret = ds2780_read8(dev_info->w1_dev, &sense_resistor, DS2780_RSNSP_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = sprintf(buf, "%d\n", sense_resistor);
> +	return ret;
> +}
> +
> +static ssize_t ds2780_set_sense_resistor_value(struct device *dev,
> +	struct device_attribute *attr,
> +	const char *buf,
> +	size_t count)
> +{
> +	int ret;
> +	u8 new_setting;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	ret = kstrtou8(buf, 0, &new_setting);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ds2780_set_sense_register(dev_info, new_setting);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t ds2780_get_rsgain_setting(struct device *dev,
> +	struct device_attribute *attr,
> +	char *buf)
> +{
> +	int ret;
> +	u16 rsgain;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	ret = ds2780_get_rsgain_register(dev_info, &rsgain);
> +	if (ret < 0)
> +		return ret;
> +
> +	return sprintf(buf, "%d\n", rsgain);
> +}
> +
> +static ssize_t ds2780_set_rsgain_setting(struct device *dev,
> +	struct device_attribute *attr,
> +	const char *buf,
> +	size_t count)
> +{
> +	int ret;
> +	u16 new_setting;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	ret = kstrtou16(buf, 0, &new_setting);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Gain can only be from 0 to 1.999 in steps of .001 */
> +	if (new_setting > 1999) {
> +		dev_err(dev_info->dev, "Invalid rsgain setting (0 - 1999)\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = ds2780_set_rsgain_register(dev_info, new_setting);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t ds2780_get_pio_pin(struct device *dev,
> +	struct device_attribute *attr,
> +	char *buf)
> +{
> +	int ret;
> +	u8 sfr;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	ret = ds2780_read8(dev_info->w1_dev, &sfr, DS2780_SFR_REG);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = sprintf(buf, "%d\n", sfr & DS2780_SFR_REG_PIOSC);
> +	return ret;
> +}
> +
> +static ssize_t ds2780_set_pio_pin(struct device *dev,
> +	struct device_attribute *attr,
> +	const char *buf,
> +	size_t count)
> +{
> +	int ret;
> +	u8 new_setting;
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	ret = kstrtou8(buf, 0, &new_setting);
> +	if (ret < 0)
> +		return ret;
> +
> +	if ((new_setting != 0) && (new_setting != 1)) {
> +		dev_err(dev_info->dev, "Invalid pio_pin setting (0 or 1)\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = ds2780_write(dev_info->w1_dev, &new_setting,
> +				DS2780_SFR_REG, sizeof(u8));
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t ds2780_read_param_eeprom_bin(struct file *filp,
> +				struct kobject *kobj,
> +				struct bin_attribute *bin_attr,
> +				char *buf, loff_t off, size_t count)
> +{
> +	struct device *dev = container_of(kobj, struct device, kobj);
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	count = min((loff_t)count,
> +		DS2780_EEPROM_BLOCK1_END -
> +		DS2780_EEPROM_BLOCK1_START + 1 - off);

You can use min_t instead of casting here.

> +
> +	return ds2780_read_block(dev_info->w1_dev, buf,
> +				DS2780_EEPROM_BLOCK1_START + off, count);
> +}
> +
> +static ssize_t ds2780_write_param_eeprom_bin(struct file *filp,
> +				struct kobject *kobj,
> +				struct bin_attribute *bin_attr,
> +				char *buf, loff_t off, size_t count)
> +{
> +	struct device *dev = container_of(kobj, struct device, kobj);
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +	int ret;
> +
> +	count = min((loff_t)count,
> +		DS2780_EEPROM_BLOCK1_END -
> +		DS2780_EEPROM_BLOCK1_START + 1 - off);
> +
> +	ret = ds2780_write(dev_info->w1_dev, buf,
> +				DS2780_EEPROM_BLOCK1_START + off, count);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ds2780_save_eeprom(dev_info, DS2780_EEPROM_BLOCK1_START);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static struct bin_attribute ds2780_param_eeprom_bin_attr = {
> +	.attr = {
> +		.name = "param_eeprom",
> +		.mode = S_IRUGO | S_IWUSR,
> +	},
> +	.size = DS2780_EEPROM_BLOCK1_END - DS2780_EEPROM_BLOCK1_START + 1,
> +	.read = ds2780_read_param_eeprom_bin,
> +	.write = ds2780_write_param_eeprom_bin,
> +};
> +
> +static ssize_t ds2780_read_user_eeprom_bin(struct file *filp,
> +				struct kobject *kobj,
> +				struct bin_attribute *bin_attr,
> +				char *buf, loff_t off, size_t count)
> +{
> +	struct device *dev = container_of(kobj, struct device, kobj);
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +
> +	count = min((loff_t)count,
> +		DS2780_EEPROM_BLOCK0_END -
> +		DS2780_EEPROM_BLOCK0_START + 1 - off);
> +
> +	return ds2780_read_block(dev_info->w1_dev, buf,
> +				DS2780_EEPROM_BLOCK0_START + off, count);
> +
> +}
> +
> +static ssize_t ds2780_write_user_eeprom_bin(struct file *filp,
> +				struct kobject *kobj,
> +				struct bin_attribute *bin_attr,
> +				char *buf, loff_t off, size_t count)
> +{
> +	struct device *dev = container_of(kobj, struct device, kobj);
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
> +	int ret;
> +
> +	count = min((loff_t)count,
> +		DS2780_EEPROM_BLOCK0_END -
> +		DS2780_EEPROM_BLOCK0_START + 1 - off);
> +
> +	ret = ds2780_write(dev_info->w1_dev, buf,
> +				DS2780_EEPROM_BLOCK0_START + off, count);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ds2780_save_eeprom(dev_info, DS2780_EEPROM_BLOCK0_START);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static struct bin_attribute ds2780_user_eeprom_bin_attr = {
> +	.attr = {
> +		.name = "user_eeprom",
> +		.mode = S_IRUGO | S_IWUSR,
> +	},
> +	.size = DS2780_EEPROM_BLOCK0_END - DS2780_EEPROM_BLOCK0_START + 1,
> +	.read = ds2780_read_user_eeprom_bin,
> +	.write = ds2780_write_user_eeprom_bin,
> +};
> +
> +static DEVICE_ATTR(pmod_enabled, S_IRUGO | S_IWUSR, ds2780_get_pmod_enabled,
> +	ds2780_set_pmod_enabled);
> +static DEVICE_ATTR(sense_resistor_value, S_IRUGO | S_IWUSR,
> +	ds2780_get_sense_resistor_value, ds2780_set_sense_resistor_value);
> +static DEVICE_ATTR(rsgain_setting, S_IRUGO | S_IWUSR, ds2780_get_rsgain_setting,
> +	ds2780_set_rsgain_setting);
> +static DEVICE_ATTR(pio_pin, S_IRUGO | S_IWUSR, ds2780_get_pio_pin,
> +	ds2780_set_pio_pin);
> +
> +
> +static struct attribute *ds2780_attributes[] = {
> +	&dev_attr_pmod_enabled.attr,
> +	&dev_attr_sense_resistor_value.attr,
> +	&dev_attr_rsgain_setting.attr,
> +	&dev_attr_pio_pin.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group ds2780_attr_group = {
> +	.attrs = ds2780_attributes,
> +};
> +
> +static int __devinit ds2780_battery_probe(struct platform_device *pdev)
> +{
> +	int ret = 0;
> +	struct ds2780_device_info *dev_info;
> +
> +	dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
> +	if (!dev_info) {
> +		ret = -ENOMEM;

If ret is initialised to -ENOMEM above this clause becomes a bit
simpler. ret will still get set correctly by power_supply_register below.

> +		goto fail;
> +	}
> +
> +	platform_set_drvdata(pdev, dev_info);
> +
> +	dev_info->dev			= &pdev->dev;
> +	dev_info->w1_dev		= pdev->dev.parent;
> +	dev_info->bat.name		= dev_name(&pdev->dev);
> +	dev_info->bat.type		= POWER_SUPPLY_TYPE_BATTERY;
> +	dev_info->bat.properties	= ds2780_battery_props;
> +	dev_info->bat.num_properties	= ARRAY_SIZE(ds2780_battery_props);
> +	dev_info->bat.get_property	= ds2780_battery_get_property;
> +
> +	ret = power_supply_register(&pdev->dev, &dev_info->bat);
> +	if (ret) {
> +		dev_err(dev_info->dev, "failed to register battery\n");
> +		goto fail_free_info;
> +	}
> +
> +	ret = sysfs_create_group(&dev_info->bat.dev->kobj, &ds2780_attr_group);
> +	if (ret) {
> +		dev_err(dev_info->dev, "failed to create sysfs group\n");
> +		goto fail_unregister;
> +	}
> +
> +	ret = sysfs_create_bin_file(&dev_info->bat.dev->kobj,
> +					&ds2780_param_eeprom_bin_attr);
> +	if (ret) {
> +		dev_err(dev_info->dev,
> +				"failed to create param eeprom bin file");
> +		goto fail_remove_group;
> +	}
> +
> +	ret = sysfs_create_bin_file(&dev_info->bat.dev->kobj,
> +					&ds2780_user_eeprom_bin_attr);
> +	if (ret) {
> +		dev_err(dev_info->dev,
> +				"failed to create user eeprom bin file");
> +		goto fail_remove_bin_file;
> +	}
> +
> +	return 0;
> +
> +fail_remove_bin_file:
> +	sysfs_remove_bin_file(&dev_info->bat.dev->kobj,
> +				&ds2780_param_eeprom_bin_attr);
> +fail_remove_group:
> +	sysfs_remove_group(&dev_info->bat.dev->kobj, &ds2780_attr_group);
> +fail_unregister:
> +	power_supply_unregister(&dev_info->bat);
> +fail_free_info:
> +	kfree(dev_info);
> +fail:
> +	return ret;
> +}
> +
> +static int __devexit ds2780_battery_remove(struct platform_device *pdev)
> +{
> +	struct ds2780_device_info *dev_info = platform_get_drvdata(pdev);
> +
> +	/* remove attributes */
> +	sysfs_remove_group(&dev_info->bat.dev->kobj, &ds2780_attr_group);
> +
> +	power_supply_unregister(&dev_info->bat);
> +
> +	kfree(dev_info);
> +	return 0;
> +}
> +
> +MODULE_ALIAS("platform:ds2780-battery");
> +
> +static struct platform_driver ds2780_battery_driver = {
> +	.driver = {
> +		.name = "ds2780-battery",
> +	},
> +	.probe	  = ds2780_battery_probe,
> +	.remove   = ds2780_battery_remove,
> +};
> +
> +static int __init ds2780_battery_init(void)
> +{
> +	return platform_driver_register(&ds2780_battery_driver);
> +}
> +
> +static void __exit ds2780_battery_exit(void)
> +{
> +	platform_driver_unregister(&ds2780_battery_driver);
> +}
> +
> +module_init(ds2780_battery_init);
> +module_exit(ds2780_battery_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Clifton Barnes <cabarnes@indesign-llc.com>");
> +MODULE_DESCRIPTION("Maxim/Dallas DS2780 Stand-Alone Fuel Gauage IC driver");
> diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig
> index f0c9096..d9fa263 100644
> --- a/drivers/w1/slaves/Kconfig
> +++ b/drivers/w1/slaves/Kconfig
> @@ -61,6 +61,19 @@ config W1_SLAVE_DS2760
>  
>  	  If you are unsure, say N.
>  
> +config W1_SLAVE_DS2780
> +	tristate "Dallas 2780 battery monitor chip"
> +	depends on W1
> +	help
> +	  If you enable this you will have the DS2780 battery monitor
> +	  chip support.
> +
> +	  The battery monitor chip is used in many batteries/devices
> +	  as the one who is responsible for charging/discharging/monitoring
> +	  Li+ batteries.
> +
> +	  If you are unsure, say N.
> +

Not auto-selected by CONFIG_DS2780_BATTERY? Is it useful to have
CONFIG_W1_SLAVE_DS2780 on its own?

>  config W1_SLAVE_BQ27000
>  	tristate "BQ27000 slave support"
>  	depends on W1
> diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
> index 3c76350..00c9134 100644
> --- a/drivers/w1/slaves/Makefile
> +++ b/drivers/w1/slaves/Makefile
> @@ -8,4 +8,5 @@ obj-$(CONFIG_W1_SLAVE_DS2423)	+= w1_ds2423.o
>  obj-$(CONFIG_W1_SLAVE_DS2431)	+= w1_ds2431.o
>  obj-$(CONFIG_W1_SLAVE_DS2433)	+= w1_ds2433.o
>  obj-$(CONFIG_W1_SLAVE_DS2760)	+= w1_ds2760.o
> +obj-$(CONFIG_W1_SLAVE_DS2780)	+= w1_ds2780.o
>  obj-$(CONFIG_W1_SLAVE_BQ27000)	+= w1_bq27000.o
> diff --git a/drivers/w1/slaves/w1_ds2780.c b/drivers/w1/slaves/w1_ds2780.c
> new file mode 100644
> index 0000000..8ea2d45
> --- /dev/null
> +++ b/drivers/w1/slaves/w1_ds2780.c
> @@ -0,0 +1,217 @@
> +/*
> + * 1-Wire implementation for the ds2780 chip
> + *
> + * Copyright (C) 2010 Indesign, LLC
> + *
> + * Author: Clifton Barnes <cabarnes@indesign-llc.com>
> + *
> + * Based on w1-ds2760 driver
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/types.h>
> +#include <linux/platform_device.h>
> +#include <linux/mutex.h>
> +#include <linux/idr.h>
> +
> +#include "../w1.h"
> +#include "../w1_int.h"
> +#include "../w1_family.h"
> +#include "w1_ds2780.h"
> +
> +int w1_ds2780_io(struct device *dev, char *buf, int addr, size_t count,
> +			int io)
> +{
> +	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
> +
> +	if (!dev)
> +		return -ENODEV;
> +
> +	mutex_lock(&sl->master->mutex);
> +
> +	if (addr > DS2780_DATA_SIZE || addr < 0) {
> +		count = 0;
> +		goto out;
> +	}
> +	count = min((int)count, DS2780_DATA_SIZE - addr);

min_t

> +
> +	if (w1_reset_select_slave(sl) == 0) {
> +		if (io) {
> +			w1_write_8(sl->master, W1_DS2780_WRITE_DATA);
> +			w1_write_8(sl->master, addr);
> +			w1_write_block(sl->master, buf, count);
> +			/* XXX w1_write_block returns void, not n_written */

This comment can possibly be removed?

> +		} else {
> +			w1_write_8(sl->master, W1_DS2780_READ_DATA);
> +			w1_write_8(sl->master, addr);
> +			count = w1_read_block(sl->master, buf, count);
> +		}
> +	}
> +
> +out:
> +	mutex_unlock(&sl->master->mutex);
> +
> +	return count;
> +}
> +EXPORT_SYMBOL(w1_ds2780_io);
> +
> +int w1_ds2780_eeprom_cmd(struct device *dev, int addr, int cmd)
> +{
> +	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
> +
> +	if (!dev)
> +		return -EINVAL;
> +
> +	mutex_lock(&sl->master->mutex);
> +
> +	if (w1_reset_select_slave(sl) == 0) {
> +		w1_write_8(sl->master, cmd);
> +		w1_write_8(sl->master, addr);
> +	}
> +
> +	mutex_unlock(&sl->master->mutex);
> +	return 0;
> +}
> +EXPORT_SYMBOL(w1_ds2780_eeprom_cmd);
> +
> +static ssize_t w1_ds2780_read_bin(struct file *filp,
> +				  struct kobject *kobj,
> +				  struct bin_attribute *bin_attr,
> +				  char *buf, loff_t off, size_t count)
> +{
> +	struct device *dev = container_of(kobj, struct device, kobj);
> +	return w1_ds2780_io(dev, buf, off, count, 0);
> +}
> +
> +static struct bin_attribute w1_ds2780_bin_attr = {
> +	.attr = {
> +		.name = "w1_slave",
> +		.mode = S_IRUGO,
> +	},
> +	.size = DS2780_DATA_SIZE,
> +	.read = w1_ds2780_read_bin,
> +};
> +
> +static DEFINE_IDR(bat_idr);
> +static DEFINE_MUTEX(bat_idr_lock);
> +
> +static int new_bat_id(void)
> +{
> +	int ret;
> +
> +	while (1) {
> +		int id;
> +
> +		ret = idr_pre_get(&bat_idr, GFP_KERNEL);
> +		if (ret == 0)
> +			return -ENOMEM;
> +
> +		mutex_lock(&bat_idr_lock);
> +		ret = idr_get_new(&bat_idr, NULL, &id);
> +		mutex_unlock(&bat_idr_lock);
> +
> +		if (ret == 0) {
> +			ret = id & MAX_ID_MASK;
> +			break;
> +		} else if (ret == -EAGAIN) {
> +			continue;
> +		} else {
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static void release_bat_id(int id)
> +{
> +	mutex_lock(&bat_idr_lock);
> +	idr_remove(&bat_idr, id);
> +	mutex_unlock(&bat_idr_lock);
> +}
> +
> +static int w1_ds2780_add_slave(struct w1_slave *sl)
> +{
> +	int ret;
> +	int id;
> +	struct platform_device *pdev;
> +
> +	id = new_bat_id();
> +	if (id < 0) {
> +		ret = id;
> +		goto noid;
> +	}
> +
> +	pdev = platform_device_alloc("ds2780-battery", id);
> +	if (!pdev) {
> +		ret = -ENOMEM;
> +		goto pdev_alloc_failed;
> +	}
> +	pdev->dev.parent = &sl->dev;
> +
> +	ret = platform_device_add(pdev);
> +	if (ret)
> +		goto pdev_add_failed;
> +
> +	ret = sysfs_create_bin_file(&sl->dev.kobj, &w1_ds2780_bin_attr);
> +	if (ret)
> +		goto bin_attr_failed;
> +
> +	dev_set_drvdata(&sl->dev, pdev);
> +
> +	return 0;
> +
> +bin_attr_failed:
> +pdev_add_failed:
> +	platform_device_unregister(pdev);
> +pdev_alloc_failed:
> +	release_bat_id(id);
> +noid:
> +	return ret;
> +}
> +
> +static void w1_ds2780_remove_slave(struct w1_slave *sl)
> +{
> +	struct platform_device *pdev = dev_get_drvdata(&sl->dev);
> +	int id = pdev->id;
> +
> +	platform_device_unregister(pdev);
> +	release_bat_id(id);
> +	sysfs_remove_bin_file(&sl->dev.kobj, &w1_ds2780_bin_attr);
> +}
> +
> +static struct w1_family_ops w1_ds2780_fops = {
> +	.add_slave    = w1_ds2780_add_slave,
> +	.remove_slave = w1_ds2780_remove_slave,
> +};
> +
> +static struct w1_family w1_ds2780_family = {
> +	.fid = W1_FAMILY_DS2780,
> +	.fops = &w1_ds2780_fops,
> +};
> +
> +static int __init w1_ds2780_init(void)
> +{
> +	idr_init(&bat_idr);
> +	return w1_register_family(&w1_ds2780_family);
> +}
> +
> +static void __exit w1_ds2780_exit(void)
> +{
> +	w1_unregister_family(&w1_ds2780_family);
> +	idr_destroy(&bat_idr);
> +}
> +
> +module_init(w1_ds2780_init);
> +module_exit(w1_ds2780_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Clifton Barnes <cabarnes@indesign-llc.com>");
> +MODULE_DESCRIPTION("1-wire Driver for Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC");
> diff --git a/drivers/w1/slaves/w1_ds2780.h b/drivers/w1/slaves/w1_ds2780.h
> new file mode 100644
> index 0000000..a1fba79
> --- /dev/null
> +++ b/drivers/w1/slaves/w1_ds2780.h
> @@ -0,0 +1,129 @@
> +/*
> + * 1-Wire implementation for the ds2780 chip
> + *
> + * Copyright (C) 2010 Indesign, LLC
> + *
> + * Author: Clifton Barnes <cabarnes@indesign-llc.com>
> + *
> + * Based on w1-ds2760 driver
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + */
> +
> +#ifndef _W1_DS2780_H
> +#define _W1_DS2780_H
> +
> +/* Function commands */
> +#define W1_DS2780_READ_DATA		0x69
> +#define W1_DS2780_WRITE_DATA		0x6C
> +#define W1_DS2780_COPY_DATA		0x48
> +#define W1_DS2780_RECALL_DATA		0xB8
> +#define W1_DS2780_LOCK			0x6A
> +
> +/* Register map */
> +/* Register 0x00 Reserved */
> +#define DS2780_STATUS_REG		0x01
> +#define DS2780_RAAC_MSB_REG		0x02
> +#define DS2780_RAAC_LSB_REG		0x03
> +#define DS2780_RSAC_MSB_REG		0x04
> +#define DS2780_RSAC_LSB_REG		0x05
> +#define DS2780_RARC_REG			0x06
> +#define DS2780_RSRC_REG			0x07
> +#define DS2780_IAVG_MSB_REG		0x08
> +#define DS2780_IAVG_LSB_REG		0x09
> +#define DS2780_TEMP_MSB_REG		0x0A
> +#define DS2780_TEMP_LSB_REG		0x0B
> +#define DS2780_VOLT_MSB_REG		0x0C
> +#define DS2780_VOLT_LSB_REG		0x0D
> +#define DS2780_CURRENT_MSB_REG		0x0E
> +#define DS2780_CURRENT_LSB_REG		0x0F
> +#define DS2780_ACR_MSB_REG		0x10
> +#define DS2780_ACR_LSB_REG		0x11
> +#define DS2780_ACRL_MSB_REG		0x12
> +#define DS2780_ACRL_LSB_REG		0x13
> +#define DS2780_AS_REG			0x14
> +#define DS2780_SFR_REG			0x15
> +#define DS2780_FULL_MSB_REG		0x16
> +#define DS2780_FULL_LSB_REG		0x17
> +#define DS2780_AE_MSB_REG		0x18
> +#define DS2780_AE_LSB_REG		0x19
> +#define DS2780_SE_MSB_REG		0x1A
> +#define DS2780_SE_LSB_REG		0x1B
> +/* Register 0x1C - 0x1E Reserved */
> +#define DS2780_EEPROM_REG		0x1F
> +#define DS2780_EEPROM_BLOCK0_START	0x20
> +/* Register 0x20 - 0x2F User EEPROM */
> +#define DS2780_EEPROM_BLOCK0_END	0x2F
> +/* Register 0x30 - 0x5F Reserved */
> +#define DS2780_EEPROM_BLOCK1_START	0x60
> +#define DS2780_CONTROL_REG		0x60
> +#define DS2780_AB_REG			0x61
> +#define DS2780_AC_MSB_REG		0x62
> +#define DS2780_AC_LSB_REG		0x63
> +#define DS2780_VCHG_REG			0x64
> +#define DS2780_IMIN_REG			0x65
> +#define DS2780_VAE_REG			0x66
> +#define DS2780_IAE_REG			0x67
> +#define DS2780_AE_40_REG		0x68
> +#define DS2780_RSNSP_REG		0x69
> +#define DS2780_FULL_40_MSB_REG		0x6A
> +#define DS2780_FULL_40_LSB_REG		0x6B
> +#define DS2780_FULL_3040_SLOPE_REG	0x6C
> +#define DS2780_FULL_2030_SLOPE_REG	0x6D
> +#define DS2780_FULL_1020_SLOPE_REG	0x6E
> +#define DS2780_FULL_0010_SLOPE_REG	0x6F
> +#define DS2780_AE_3040_SLOPE_REG	0x70
> +#define DS2780_AE_2030_SLOPE_REG	0x71
> +#define DS2780_AE_1020_SLOPE_REG	0x72
> +#define DS2780_AE_0010_SLOPE_REG	0x73
> +#define DS2780_SE_3040_SLOPE_REG	0x74
> +#define DS2780_SE_2030_SLOPE_REG	0x75
> +#define DS2780_SE_1020_SLOPE_REG	0x76
> +#define DS2780_SE_0010_SLOPE_REG	0x77
> +#define DS2780_RSGAIN_MSB_REG		0x78
> +#define DS2780_RSGAIN_LSB_REG		0x79
> +#define DS2780_RSTC_REG			0x7A
> +#define DS2780_FRSGAIN_MSB_REG		0x7B
> +#define DS2780_FRSGAIN_LSB_REG		0x7C
> +#define DS2780_EEPROM_BLOCK1_END	0x7C
> +/* Register 0x7D - 0xFF Reserved */
> +
> +/* Number of valid register addresses */
> +#define DS2780_DATA_SIZE		0x80
> +
> +/* Status register bits */
> +#define DS2780_STATUS_REG_CHGTF		(1 << 7)
> +#define DS2780_STATUS_REG_AEF		(1 << 6)
> +#define DS2780_STATUS_REG_SEF		(1 << 5)
> +#define DS2780_STATUS_REG_LEARNF	(1 << 4)
> +/* Bit 3 Reserved */
> +#define DS2780_STATUS_REG_UVF		(1 << 2)
> +#define DS2780_STATUS_REG_PORF		(1 << 1)
> +/* Bit 0 Reserved */
> +
> +/* Control register bits */
> +/* Bit 7 Reserved */
> +#define DS2780_CONTROL_REG_UVEN		(1 << 6)
> +#define DS2780_CONTROL_REG_PMOD		(1 << 5)
> +#define DS2780_CONTROL_REG_RNAOP	(1 << 4)
> +/* Bit 0 - 3 Reserved */
> +
> +/* Special feature register bits */
> +/* Bit 1 - 7 Reserved */
> +#define DS2780_SFR_REG_PIOSC		(1 << 0)
> +
> +/* EEPROM register bits */
> +#define DS2780_EEPROM_REG_EEC		(1 << 7)
> +#define DS2780_EEPROM_REG_LOCK		(1 << 6)
> +/* Bit 2 - 6 Reserved */
> +#define DS2780_EEPROM_REG_BL1		(1 << 1)
> +#define DS2780_EEPROM_REG_BL0		(1 << 0)
> +
> +extern int w1_ds2780_io(struct device *dev, char *buf, int addr, size_t count,
> +			int io);
> +extern int w1_ds2780_eeprom_cmd(struct device *dev, int addr, int cmd);
> +
> +#endif /* !_W1_DS2780_H */
> diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
> index f3b636d..e76125c 100644
> --- a/drivers/w1/w1_family.h
> +++ b/drivers/w1/w1_family.h
> @@ -36,6 +36,7 @@
>  #define W1_THERM_DS18B20 	0x28
>  #define W1_EEPROM_DS2431	0x2D
>  #define W1_FAMILY_DS2760	0x30
> +#define W1_FAMILY_DS2780	0x32
>  
>  #define MAXNAMELEN		32
>  


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

Re: [PATCH v3] w1: Add Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC support.

[Andrew Morton]

On Thu, 19 May 2011 08:21:09 -0400
Clifton Barnes <cabarnes@indesign-llc.com> wrote:

> Add support for the Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC.
> 
> I've updated the driver based on feedback from the last version.
> I believe the locking is correct because the w1_ds2780_io function
> has locking in it.  If there's still a problem that I'm missing let 
> me know and I can correct it.
> 
> Changes for v3:
>  - Formatting changes suggested from last version
>  - Moved read/write functions to battery driver
>  - Corrected temperature calculation
>  - Changed EEPROM access to bin_attribute
> 

We have a min_t() helper to avoid (or hide) the typecasts:

--- a/drivers/power/ds2780_battery.c~w1-add-maxim-dallas-ds2780-stand-alone-fuel-gauge-ic-support-v3-fix
+++ a/drivers/power/ds2780_battery.c
@@ -628,7 +628,7 @@ static ssize_t ds2780_read_param_eeprom_
 	struct power_supply *psy = to_power_supply(dev);
 	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
 
-	count = min((loff_t)count,
+	count = min_t(loff_t, count,
 		DS2780_EEPROM_BLOCK1_END -
 		DS2780_EEPROM_BLOCK1_START + 1 - off);
 
@@ -646,7 +646,7 @@ static ssize_t ds2780_write_param_eeprom
 	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
 	int ret;
 
-	count = min((loff_t)count,
+	count = min_t(loff_t, count,
 		DS2780_EEPROM_BLOCK1_END -
 		DS2780_EEPROM_BLOCK1_START + 1 - off);
 
@@ -681,7 +681,7 @@ static ssize_t ds2780_read_user_eeprom_b
 	struct power_supply *psy = to_power_supply(dev);
 	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
 
-	count = min((loff_t)count,
+	count = min_t(loff_t, count,
 		DS2780_EEPROM_BLOCK0_END -
 		DS2780_EEPROM_BLOCK0_START + 1 - off);
 
@@ -700,7 +700,7 @@ static ssize_t ds2780_write_user_eeprom_
 	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
 	int ret;
 
-	count = min((loff_t)count,
+	count = min_t(loff_t, count,
 		DS2780_EEPROM_BLOCK0_END -
 		DS2780_EEPROM_BLOCK0_START + 1 - off);
 
--- a/drivers/w1/slaves/w1_ds2780.c~w1-add-maxim-dallas-ds2780-stand-alone-fuel-gauge-ic-support-v3-fix
+++ a/drivers/w1/slaves/w1_ds2780.c
@@ -40,7 +40,7 @@ int w1_ds2780_io(struct device *dev, cha
 		count = 0;
 		goto out;
 	}
-	count = min((int)count, DS2780_DATA_SIZE - addr);
+	count = min_t(int, count, DS2780_DATA_SIZE - addr);
 
 	if (w1_reset_select_slave(sl) == 0) {
 		if (io) {
_


However its use is often a sign that some types were unwisely chosen.

[PATCH v3] w1: Add Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC support.

[Clifton Barnes]

Add support for the Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC.

I've updated the driver based on feedback from the last version.
I believe the locking is correct because the w1_ds2780_io function
has locking in it.  If there's still a problem that I'm missing let 
me know and I can correct it.

Changes for v3:
 - Formatting changes suggested from last version
 - Moved read/write functions to battery driver
 - Corrected temperature calculation
 - Changed EEPROM access to bin_attribute

Signed-off-by: Clifton Barnes <cabarnes@indesign-llc.com>
---
 drivers/power/Kconfig          |    7 +
 drivers/power/Makefile         |    1 +
 drivers/power/ds2780_battery.c |  853 ++++++++++++++++++++++++++++++++++++++++
 drivers/w1/slaves/Kconfig      |   13 +
 drivers/w1/slaves/Makefile     |    1 +
 drivers/w1/slaves/w1_ds2780.c  |  217 ++++++++++
 drivers/w1/slaves/w1_ds2780.h  |  129 ++++++
 drivers/w1/w1_family.h         |    1 +
 8 files changed, 1222 insertions(+), 0 deletions(-)
 create mode 100644 drivers/power/ds2780_battery.c
 create mode 100644 drivers/w1/slaves/w1_ds2780.c
 create mode 100644 drivers/w1/slaves/w1_ds2780.h

diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 52a462f..dc8c531 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -68,6 +68,13 @@ config BATTERY_DS2760
 	help
 	  Say Y here to enable support for batteries with ds2760 chip.
 
+config BATTERY_DS2780
+	tristate "DS2780 battery driver"
+	select W1
+	select W1_SLAVE_DS2780
+	help
+	  Say Y here to enable support for batteries with ds2780 chip.
+
 config BATTERY_DS2782
 	tristate "DS2782/DS2786 standalone gas-gauge"
 	depends on I2C
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index 8385bfa..8224990 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_WM8350_POWER)	+= wm8350_power.o
 obj-$(CONFIG_TEST_POWER)	+= test_power.o
 
 obj-$(CONFIG_BATTERY_DS2760)	+= ds2760_battery.o
+obj-$(CONFIG_BATTERY_DS2780)	+= ds2780_battery.o
 obj-$(CONFIG_BATTERY_DS2782)	+= ds2782_battery.o
 obj-$(CONFIG_BATTERY_PMU)	+= pmu_battery.o
 obj-$(CONFIG_BATTERY_OLPC)	+= olpc_battery.o
diff --git a/drivers/power/ds2780_battery.c b/drivers/power/ds2780_battery.c
new file mode 100644
index 0000000..55362dd
--- /dev/null
+++ b/drivers/power/ds2780_battery.c
@@ -0,0 +1,853 @@
+/*
+ * 1-wire client/driver for the Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC
+ *
+ * Copyright (C) 2010 Indesign, LLC
+ *
+ * Author: Clifton Barnes <cabarnes@indesign-llc.com>
+ *
+ * Based on ds2760_battery and ds2782_battery drivers
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/param.h>
+#include <linux/pm.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/idr.h>
+
+#include "../w1/w1.h"
+#include "../w1/slaves/w1_ds2780.h"
+
+/* Current unit measurement in uA for a 1 milli-ohm sense resistor */
+#define DS2780_CURRENT_UNITS	1563
+/* Charge unit measurement in uAh for a 1 milli-ohm sense resistor */
+#define DS2780_CHARGE_UNITS		6250
+/* Number of bytes in user EEPROM space */
+#define DS2780_USER_EEPROM_SIZE		(DS2780_EEPROM_BLOCK0_END - \
+					DS2780_EEPROM_BLOCK0_START + 1)
+/* Number of bytes in parameter EEPROM space */
+#define DS2780_PARAM_EEPROM_SIZE	(DS2780_EEPROM_BLOCK1_END - \
+					DS2780_EEPROM_BLOCK1_START + 1)
+
+struct ds2780_device_info {
+	struct device *dev;
+	struct power_supply bat;
+	struct device *w1_dev;
+};
+
+enum current_types {
+	CURRENT_NOW,
+	CURRENT_AVG,
+};
+
+static const char model[] = "DS2780";
+static const char manufacturer[] = "Maxim/Dallas";
+
+static inline struct ds2780_device_info *to_ds2780_device_info(
+	struct power_supply *psy)
+{
+	return container_of(psy, struct ds2780_device_info, bat);
+}
+
+static inline struct power_supply *to_power_supply(struct device *dev)
+{
+	return dev_get_drvdata(dev);
+}
+
+static inline int ds2780_read8(struct device *dev, u8 *val, int addr)
+{
+	return w1_ds2780_io(dev, val, addr, sizeof(u8), 0);
+}
+
+static int ds2780_read16(struct device *dev, s16 *val, int addr)
+{
+	int ret;
+	u8 raw[2];
+
+	ret = w1_ds2780_io(dev, raw, addr, sizeof(u8) * 2, 0);
+	if (ret < 0)
+		return ret;
+
+	*val = (raw[0] << 8) | raw[1];
+
+	return 0;
+}
+
+static inline int ds2780_read_block(struct device *dev, u8 *val, int addr,
+	size_t count)
+{
+	return w1_ds2780_io(dev, val, addr, count, 0);
+}
+
+static inline int ds2780_write(struct device *dev, u8 *val, int addr,
+	size_t count)
+{
+	return w1_ds2780_io(dev, val, addr, count, 1);
+}
+
+static inline int ds2780_store_eeprom(struct device *dev, int addr)
+{
+	return w1_ds2780_eeprom_cmd(dev, addr, W1_DS2780_COPY_DATA);
+}
+
+static inline int ds2780_recall_eeprom(struct device *dev, int addr)
+{
+	return w1_ds2780_eeprom_cmd(dev, addr, W1_DS2780_RECALL_DATA);
+}
+
+static int ds2780_save_eeprom(struct ds2780_device_info *dev_info, int reg)
+{
+	int ret;
+
+	ret = ds2780_store_eeprom(dev_info->w1_dev, reg);
+	if (ret < 0)
+		return ret;
+
+	ret = ds2780_recall_eeprom(dev_info->w1_dev, reg);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+/* Set sense resistor value in mhos */
+static int ds2780_set_sense_register(struct ds2780_device_info *dev_info,
+	u8 conductance)
+{
+	int ret;
+
+	ret = ds2780_write(dev_info->w1_dev, &conductance,
+				DS2780_RSNSP_REG, sizeof(u8));
+	if (ret < 0)
+		return ret;
+
+	return ds2780_save_eeprom(dev_info, DS2780_RSNSP_REG);
+}
+
+/* Get RSGAIN value from 0 to 1.999 in steps of 0.001 */
+static int ds2780_get_rsgain_register(struct ds2780_device_info *dev_info,
+	u16 *rsgain)
+{
+	return ds2780_read16(dev_info->w1_dev, rsgain, DS2780_RSGAIN_MSB_REG);
+}
+
+/* Set RSGAIN value from 0 to 1.999 in steps of 0.001 */
+static int ds2780_set_rsgain_register(struct ds2780_device_info *dev_info,
+	u16 rsgain)
+{
+	int ret;
+	u8 raw[] = {rsgain >> 8, rsgain & 0xFF};
+
+	ret = ds2780_write(dev_info->w1_dev, raw,
+				DS2780_RSGAIN_MSB_REG, sizeof(u8) * 2);
+	if (ret < 0)
+		return ret;
+
+	return ds2780_save_eeprom(dev_info, DS2780_RSGAIN_MSB_REG);
+}
+
+static int ds2780_get_voltage(struct ds2780_device_info *dev_info,
+	int *voltage_uV)
+{
+	int ret;
+	s16 voltage_raw;
+
+	/*
+	 * The voltage value is located in 10 bits across the voltage MSB
+	 * and LSB registers in two's compliment form
+	 * Sign bit of the voltage value is in bit 7 of the voltage MSB register
+	 * Bits 9 - 3 of the voltage value are in bits 6 - 0 of the
+	 * voltage MSB register
+	 * Bits 2 - 0 of the voltage value are in bits 7 - 5 of the
+	 * voltage LSB register
+	 */
+	ret = ds2780_read16(dev_info->w1_dev, &voltage_raw,
+				DS2780_VOLT_MSB_REG);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * DS2780 reports voltage in units of 4.88mV, but the battery class
+	 * reports in units of uV, so convert by multiplying by 4880.
+	 */
+	*voltage_uV = (voltage_raw / 32) * 4880;
+	return 0;
+}
+
+static int ds2780_get_temperature(struct ds2780_device_info *dev_info,
+	int *temperature)
+{
+	int ret;
+	s16 temperature_raw;
+
+	/*
+	 * The temperature value is located in 10 bits across the temperature
+	 * MSB and LSB registers in two's compliment form
+	 * Sign bit of the temperature value is in bit 7 of the temperature
+	 * MSB register
+	 * Bits 9 - 3 of the temperature value are in bits 6 - 0 of the
+	 * temperature MSB register
+	 * Bits 2 - 0 of the temperature value are in bits 7 - 5 of the
+	 * temperature LSB register
+	 */
+	ret = ds2780_read16(dev_info->w1_dev, &temperature_raw,
+				DS2780_TEMP_MSB_REG);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Temperature is measured in units of 0.125 degrees celcius, the
+	 * power_supply class measures temperature in tenths of degrees
+	 * celsius. The temperature value is stored as a 10 bit number, plus
+	 * sign in the upper bits of a 16 bit register.
+	 */
+	*temperature = ((temperature_raw / 32) * 125) / 100;
+	return 0;
+}
+
+static int ds2780_get_current(struct ds2780_device_info *dev_info,
+	enum current_types type, int *current_uA)
+{
+	int ret, sense_res;
+	s16 current_raw;
+	u8 sense_res_raw, reg_msb;
+
+	/*
+	 * The units of measurement for current are dependent on the value of
+	 * the sense resistor.
+	 */
+	ret = ds2780_read8(dev_info->w1_dev, &sense_res_raw, DS2780_RSNSP_REG);
+	if (ret < 0)
+		return ret;
+
+	if (sense_res_raw == 0) {
+		dev_err(dev_info->dev, "sense resistor value is 0\n");
+		return -ENXIO;
+	}
+	sense_res = 1000 / sense_res_raw;
+
+	if (type == CURRENT_NOW)
+		reg_msb = DS2780_CURRENT_MSB_REG;
+	else if (type == CURRENT_AVG)
+		reg_msb = DS2780_IAVG_MSB_REG;
+	else
+		return -EINVAL;
+
+	/*
+	 * The current value is located in 16 bits across the current MSB
+	 * and LSB registers in two's compliment form
+	 * Sign bit of the current value is in bit 7 of the current MSB register
+	 * Bits 14 - 8 of the current value are in bits 6 - 0 of the current
+	 * MSB register
+	 * Bits 7 - 0 of the current value are in bits 7 - 0 of the current
+	 * LSB register
+	 */
+	ret = ds2780_read16(dev_info->w1_dev, &current_raw, reg_msb);
+	if (ret < 0)
+		return ret;
+
+	*current_uA = current_raw * (DS2780_CURRENT_UNITS / sense_res);
+	return 0;
+}
+
+static int ds2780_get_accumulated_current(struct ds2780_device_info *dev_info,
+	int *accumulated_current)
+{
+	int ret, sense_res;
+	s16 current_raw;
+	u8 sense_res_raw;
+
+	/*
+	 * The units of measurement for accumulated current are dependent on
+	 * the value of the sense resistor.
+	 */
+	ret = ds2780_read8(dev_info->w1_dev, &sense_res_raw, DS2780_RSNSP_REG);
+	if (ret < 0)
+		return ret;
+
+	if (sense_res_raw == 0) {
+		dev_err(dev_info->dev, "sense resistor value is 0\n");
+		return -ENXIO;
+	}
+	sense_res = 1000 / sense_res_raw;
+
+	/*
+	 * The ACR value is located in 16 bits across the ACR MSB and
+	 * LSB registers
+	 * Bits 15 - 8 of the ACR value are in bits 7 - 0 of the ACR
+	 * MSB register
+	 * Bits 7 - 0 of the ACR value are in bits 7 - 0 of the ACR
+	 * LSB register
+	 */
+	ret = ds2780_read16(dev_info->w1_dev, &current_raw, DS2780_ACR_MSB_REG);
+	if (ret < 0)
+		return ret;
+
+	*accumulated_current = current_raw * (DS2780_CHARGE_UNITS / sense_res);
+	return 0;
+}
+
+static int ds2780_get_capacity(struct ds2780_device_info *dev_info,
+	int *capacity)
+{
+	int ret;
+	u8 raw;
+
+	ret = ds2780_read8(dev_info->w1_dev, &raw, DS2780_RARC_REG);
+	if (ret < 0)
+		return ret;
+
+	*capacity = raw;
+	return raw;
+}
+
+static int ds2780_get_status(struct ds2780_device_info *dev_info, int *status)
+{
+	int ret, current_uA, capacity;
+
+	ret = ds2780_get_current(dev_info, CURRENT_NOW, &current_uA);
+	if (ret < 0)
+		return ret;
+
+	ret = ds2780_get_capacity(dev_info, &capacity);
+	if (ret < 0)
+		return ret;
+
+	if (capacity == 100)
+		*status = POWER_SUPPLY_STATUS_FULL;
+	else if (current_uA == 0)
+		*status = POWER_SUPPLY_STATUS_NOT_CHARGING;
+	else if (current_uA < 0)
+		*status = POWER_SUPPLY_STATUS_DISCHARGING;
+	else
+		*status = POWER_SUPPLY_STATUS_CHARGING;
+
+	return 0;
+}
+
+static int ds2780_get_charge_now(struct ds2780_device_info *dev_info,
+	int *charge_now)
+{
+	int ret;
+	u16 charge_raw;
+
+	/*
+	 * The RAAC value is located in 16 bits across the RAAC MSB and
+	 * LSB registers
+	 * Bits 15 - 8 of the RAAC value are in bits 7 - 0 of the RAAC
+	 * MSB register
+	 * Bits 7 - 0 of the RAAC value are in bits 7 - 0 of the RAAC
+	 * LSB register
+	 */
+	ret = ds2780_read16(dev_info->w1_dev, &charge_raw, DS2780_RAAC_MSB_REG);
+	if (ret < 0)
+		return ret;
+
+	*charge_now = charge_raw * 1600;
+	return 0;
+}
+
+static int ds2780_get_control_register(struct ds2780_device_info *dev_info,
+	u8 *control_reg)
+{
+	return ds2780_read8(dev_info->w1_dev, control_reg, DS2780_CONTROL_REG);
+}
+
+static int ds2780_set_control_register(struct ds2780_device_info *dev_info,
+	u8 control_reg)
+{
+	int ret;
+
+	ret = ds2780_write(dev_info->w1_dev, &control_reg,
+				DS2780_CONTROL_REG, sizeof(u8));
+	if (ret < 0)
+		return ret;
+
+	return ds2780_save_eeprom(dev_info, DS2780_CONTROL_REG);
+}
+
+static int ds2780_battery_get_property(struct power_supply *psy,
+	enum power_supply_property psp,
+	union power_supply_propval *val)
+{
+	int ret = 0;
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = ds2780_get_voltage(dev_info, &val->intval);
+		break;
+
+	case POWER_SUPPLY_PROP_TEMP:
+		ret = ds2780_get_temperature(dev_info, &val->intval);
+		break;
+
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval = model;
+		break;
+
+	case POWER_SUPPLY_PROP_MANUFACTURER:
+		val->strval = manufacturer;
+		break;
+
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		ret = ds2780_get_current(dev_info, CURRENT_NOW, &val->intval);
+		break;
+
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		ret = ds2780_get_current(dev_info, CURRENT_AVG, &val->intval);
+		break;
+
+	case POWER_SUPPLY_PROP_STATUS:
+		ret = ds2780_get_status(dev_info, &val->intval);
+		break;
+
+	case POWER_SUPPLY_PROP_CAPACITY:
+		ret = ds2780_get_capacity(dev_info, &val->intval);
+		break;
+
+	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
+		ret = ds2780_get_accumulated_current(dev_info, &val->intval);
+		break;
+
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		ret = ds2780_get_charge_now(dev_info, &val->intval);
+		break;
+
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static enum power_supply_property ds2780_battery_props[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+	POWER_SUPPLY_PROP_MANUFACTURER,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CURRENT_AVG,
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_CHARGE_COUNTER,
+	POWER_SUPPLY_PROP_CHARGE_NOW,
+};
+
+static ssize_t ds2780_get_pmod_enabled(struct device *dev,
+	struct device_attribute *attr,
+	char *buf)
+{
+	int ret;
+	u8 control_reg;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	/* Get power mode */
+	ret = ds2780_get_control_register(dev_info, &control_reg);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%d\n",
+		 !!(control_reg & DS2780_CONTROL_REG_PMOD));
+}
+
+static ssize_t ds2780_set_pmod_enabled(struct device *dev,
+	struct device_attribute *attr,
+	const char *buf,
+	size_t count)
+{
+	int ret;
+	u8 control_reg, new_setting;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	/* Set power mode */
+	ret = ds2780_get_control_register(dev_info, &control_reg);
+	if (ret < 0)
+		return ret;
+
+	ret = kstrtou8(buf, 0, &new_setting);
+	if (ret < 0)
+		return ret;
+
+	if ((new_setting != 0) && (new_setting != 1)) {
+		dev_err(dev_info->dev, "Invalid pmod setting (0 or 1)\n");
+		return -EINVAL;
+	}
+
+	if (new_setting)
+		control_reg |= DS2780_CONTROL_REG_PMOD;
+	else
+		control_reg &= ~DS2780_CONTROL_REG_PMOD;
+
+	ret = ds2780_set_control_register(dev_info, control_reg);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t ds2780_get_sense_resistor_value(struct device *dev,
+	struct device_attribute *attr,
+	char *buf)
+{
+	int ret;
+	u8 sense_resistor;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	ret = ds2780_read8(dev_info->w1_dev, &sense_resistor, DS2780_RSNSP_REG);
+	if (ret < 0)
+		return ret;
+
+	ret = sprintf(buf, "%d\n", sense_resistor);
+	return ret;
+}
+
+static ssize_t ds2780_set_sense_resistor_value(struct device *dev,
+	struct device_attribute *attr,
+	const char *buf,
+	size_t count)
+{
+	int ret;
+	u8 new_setting;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	ret = kstrtou8(buf, 0, &new_setting);
+	if (ret < 0)
+		return ret;
+
+	ret = ds2780_set_sense_register(dev_info, new_setting);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t ds2780_get_rsgain_setting(struct device *dev,
+	struct device_attribute *attr,
+	char *buf)
+{
+	int ret;
+	u16 rsgain;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	ret = ds2780_get_rsgain_register(dev_info, &rsgain);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%d\n", rsgain);
+}
+
+static ssize_t ds2780_set_rsgain_setting(struct device *dev,
+	struct device_attribute *attr,
+	const char *buf,
+	size_t count)
+{
+	int ret;
+	u16 new_setting;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	ret = kstrtou16(buf, 0, &new_setting);
+	if (ret < 0)
+		return ret;
+
+	/* Gain can only be from 0 to 1.999 in steps of .001 */
+	if (new_setting > 1999) {
+		dev_err(dev_info->dev, "Invalid rsgain setting (0 - 1999)\n");
+		return -EINVAL;
+	}
+
+	ret = ds2780_set_rsgain_register(dev_info, new_setting);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t ds2780_get_pio_pin(struct device *dev,
+	struct device_attribute *attr,
+	char *buf)
+{
+	int ret;
+	u8 sfr;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	ret = ds2780_read8(dev_info->w1_dev, &sfr, DS2780_SFR_REG);
+	if (ret < 0)
+		return ret;
+
+	ret = sprintf(buf, "%d\n", sfr & DS2780_SFR_REG_PIOSC);
+	return ret;
+}
+
+static ssize_t ds2780_set_pio_pin(struct device *dev,
+	struct device_attribute *attr,
+	const char *buf,
+	size_t count)
+{
+	int ret;
+	u8 new_setting;
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	ret = kstrtou8(buf, 0, &new_setting);
+	if (ret < 0)
+		return ret;
+
+	if ((new_setting != 0) && (new_setting != 1)) {
+		dev_err(dev_info->dev, "Invalid pio_pin setting (0 or 1)\n");
+		return -EINVAL;
+	}
+
+	ret = ds2780_write(dev_info->w1_dev, &new_setting,
+				DS2780_SFR_REG, sizeof(u8));
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t ds2780_read_param_eeprom_bin(struct file *filp,
+				struct kobject *kobj,
+				struct bin_attribute *bin_attr,
+				char *buf, loff_t off, size_t count)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	count = min((loff_t)count,
+		DS2780_EEPROM_BLOCK1_END -
+		DS2780_EEPROM_BLOCK1_START + 1 - off);
+
+	return ds2780_read_block(dev_info->w1_dev, buf,
+				DS2780_EEPROM_BLOCK1_START + off, count);
+}
+
+static ssize_t ds2780_write_param_eeprom_bin(struct file *filp,
+				struct kobject *kobj,
+				struct bin_attribute *bin_attr,
+				char *buf, loff_t off, size_t count)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+	int ret;
+
+	count = min((loff_t)count,
+		DS2780_EEPROM_BLOCK1_END -
+		DS2780_EEPROM_BLOCK1_START + 1 - off);
+
+	ret = ds2780_write(dev_info->w1_dev, buf,
+				DS2780_EEPROM_BLOCK1_START + off, count);
+	if (ret < 0)
+		return ret;
+
+	ret = ds2780_save_eeprom(dev_info, DS2780_EEPROM_BLOCK1_START);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static struct bin_attribute ds2780_param_eeprom_bin_attr = {
+	.attr = {
+		.name = "param_eeprom",
+		.mode = S_IRUGO | S_IWUSR,
+	},
+	.size = DS2780_EEPROM_BLOCK1_END - DS2780_EEPROM_BLOCK1_START + 1,
+	.read = ds2780_read_param_eeprom_bin,
+	.write = ds2780_write_param_eeprom_bin,
+};
+
+static ssize_t ds2780_read_user_eeprom_bin(struct file *filp,
+				struct kobject *kobj,
+				struct bin_attribute *bin_attr,
+				char *buf, loff_t off, size_t count)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+
+	count = min((loff_t)count,
+		DS2780_EEPROM_BLOCK0_END -
+		DS2780_EEPROM_BLOCK0_START + 1 - off);
+
+	return ds2780_read_block(dev_info->w1_dev, buf,
+				DS2780_EEPROM_BLOCK0_START + off, count);
+
+}
+
+static ssize_t ds2780_write_user_eeprom_bin(struct file *filp,
+				struct kobject *kobj,
+				struct bin_attribute *bin_attr,
+				char *buf, loff_t off, size_t count)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct power_supply *psy = to_power_supply(dev);
+	struct ds2780_device_info *dev_info = to_ds2780_device_info(psy);
+	int ret;
+
+	count = min((loff_t)count,
+		DS2780_EEPROM_BLOCK0_END -
+		DS2780_EEPROM_BLOCK0_START + 1 - off);
+
+	ret = ds2780_write(dev_info->w1_dev, buf,
+				DS2780_EEPROM_BLOCK0_START + off, count);
+	if (ret < 0)
+		return ret;
+
+	ret = ds2780_save_eeprom(dev_info, DS2780_EEPROM_BLOCK0_START);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static struct bin_attribute ds2780_user_eeprom_bin_attr = {
+	.attr = {
+		.name = "user_eeprom",
+		.mode = S_IRUGO | S_IWUSR,
+	},
+	.size = DS2780_EEPROM_BLOCK0_END - DS2780_EEPROM_BLOCK0_START + 1,
+	.read = ds2780_read_user_eeprom_bin,
+	.write = ds2780_write_user_eeprom_bin,
+};
+
+static DEVICE_ATTR(pmod_enabled, S_IRUGO | S_IWUSR, ds2780_get_pmod_enabled,
+	ds2780_set_pmod_enabled);
+static DEVICE_ATTR(sense_resistor_value, S_IRUGO | S_IWUSR,
+	ds2780_get_sense_resistor_value, ds2780_set_sense_resistor_value);
+static DEVICE_ATTR(rsgain_setting, S_IRUGO | S_IWUSR, ds2780_get_rsgain_setting,
+	ds2780_set_rsgain_setting);
+static DEVICE_ATTR(pio_pin, S_IRUGO | S_IWUSR, ds2780_get_pio_pin,
+	ds2780_set_pio_pin);
+
+
+static struct attribute *ds2780_attributes[] = {
+	&dev_attr_pmod_enabled.attr,
+	&dev_attr_sense_resistor_value.attr,
+	&dev_attr_rsgain_setting.attr,
+	&dev_attr_pio_pin.attr,
+	NULL
+};
+
+static const struct attribute_group ds2780_attr_group = {
+	.attrs = ds2780_attributes,
+};
+
+static int __devinit ds2780_battery_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+	struct ds2780_device_info *dev_info;
+
+	dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
+	if (!dev_info) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	platform_set_drvdata(pdev, dev_info);
+
+	dev_info->dev			= &pdev->dev;
+	dev_info->w1_dev		= pdev->dev.parent;
+	dev_info->bat.name		= dev_name(&pdev->dev);
+	dev_info->bat.type		= POWER_SUPPLY_TYPE_BATTERY;
+	dev_info->bat.properties	= ds2780_battery_props;
+	dev_info->bat.num_properties	= ARRAY_SIZE(ds2780_battery_props);
+	dev_info->bat.get_property	= ds2780_battery_get_property;
+
+	ret = power_supply_register(&pdev->dev, &dev_info->bat);
+	if (ret) {
+		dev_err(dev_info->dev, "failed to register battery\n");
+		goto fail_free_info;
+	}
+
+	ret = sysfs_create_group(&dev_info->bat.dev->kobj, &ds2780_attr_group);
+	if (ret) {
+		dev_err(dev_info->dev, "failed to create sysfs group\n");
+		goto fail_unregister;
+	}
+
+	ret = sysfs_create_bin_file(&dev_info->bat.dev->kobj,
+					&ds2780_param_eeprom_bin_attr);
+	if (ret) {
+		dev_err(dev_info->dev,
+				"failed to create param eeprom bin file");
+		goto fail_remove_group;
+	}
+
+	ret = sysfs_create_bin_file(&dev_info->bat.dev->kobj,
+					&ds2780_user_eeprom_bin_attr);
+	if (ret) {
+		dev_err(dev_info->dev,
+				"failed to create user eeprom bin file");
+		goto fail_remove_bin_file;
+	}
+
+	return 0;
+
+fail_remove_bin_file:
+	sysfs_remove_bin_file(&dev_info->bat.dev->kobj,
+				&ds2780_param_eeprom_bin_attr);
+fail_remove_group:
+	sysfs_remove_group(&dev_info->bat.dev->kobj, &ds2780_attr_group);
+fail_unregister:
+	power_supply_unregister(&dev_info->bat);
+fail_free_info:
+	kfree(dev_info);
+fail:
+	return ret;
+}
+
+static int __devexit ds2780_battery_remove(struct platform_device *pdev)
+{
+	struct ds2780_device_info *dev_info = platform_get_drvdata(pdev);
+
+	/* remove attributes */
+	sysfs_remove_group(&dev_info->bat.dev->kobj, &ds2780_attr_group);
+
+	power_supply_unregister(&dev_info->bat);
+
+	kfree(dev_info);
+	return 0;
+}
+
+MODULE_ALIAS("platform:ds2780-battery");
+
+static struct platform_driver ds2780_battery_driver = {
+	.driver = {
+		.name = "ds2780-battery",
+	},
+	.probe	  = ds2780_battery_probe,
+	.remove   = ds2780_battery_remove,
+};
+
+static int __init ds2780_battery_init(void)
+{
+	return platform_driver_register(&ds2780_battery_driver);
+}
+
+static void __exit ds2780_battery_exit(void)
+{
+	platform_driver_unregister(&ds2780_battery_driver);
+}
+
+module_init(ds2780_battery_init);
+module_exit(ds2780_battery_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Clifton Barnes <cabarnes@indesign-llc.com>");
+MODULE_DESCRIPTION("Maxim/Dallas DS2780 Stand-Alone Fuel Gauage IC driver");
diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig
index f0c9096..d9fa263 100644
--- a/drivers/w1/slaves/Kconfig
+++ b/drivers/w1/slaves/Kconfig
@@ -61,6 +61,19 @@ config W1_SLAVE_DS2760
 
 	  If you are unsure, say N.
 
+config W1_SLAVE_DS2780
+	tristate "Dallas 2780 battery monitor chip"
+	depends on W1
+	help
+	  If you enable this you will have the DS2780 battery monitor
+	  chip support.
+
+	  The battery monitor chip is used in many batteries/devices
+	  as the one who is responsible for charging/discharging/monitoring
+	  Li+ batteries.
+
+	  If you are unsure, say N.
+
 config W1_SLAVE_BQ27000
 	tristate "BQ27000 slave support"
 	depends on W1
diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
index 3c76350..00c9134 100644
--- a/drivers/w1/slaves/Makefile
+++ b/drivers/w1/slaves/Makefile
@@ -8,4 +8,5 @@ obj-$(CONFIG_W1_SLAVE_DS2423)	+= w1_ds2423.o
 obj-$(CONFIG_W1_SLAVE_DS2431)	+= w1_ds2431.o
 obj-$(CONFIG_W1_SLAVE_DS2433)	+= w1_ds2433.o
 obj-$(CONFIG_W1_SLAVE_DS2760)	+= w1_ds2760.o
+obj-$(CONFIG_W1_SLAVE_DS2780)	+= w1_ds2780.o
 obj-$(CONFIG_W1_SLAVE_BQ27000)	+= w1_bq27000.o
diff --git a/drivers/w1/slaves/w1_ds2780.c b/drivers/w1/slaves/w1_ds2780.c
new file mode 100644
index 0000000..8ea2d45
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2780.c
@@ -0,0 +1,217 @@
+/*
+ * 1-Wire implementation for the ds2780 chip
+ *
+ * Copyright (C) 2010 Indesign, LLC
+ *
+ * Author: Clifton Barnes <cabarnes@indesign-llc.com>
+ *
+ * Based on w1-ds2760 driver
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/types.h>
+#include <linux/platform_device.h>
+#include <linux/mutex.h>
+#include <linux/idr.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+#include "../w1_family.h"
+#include "w1_ds2780.h"
+
+int w1_ds2780_io(struct device *dev, char *buf, int addr, size_t count,
+			int io)
+{
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+
+	if (!dev)
+		return -ENODEV;
+
+	mutex_lock(&sl->master->mutex);
+
+	if (addr > DS2780_DATA_SIZE || addr < 0) {
+		count = 0;
+		goto out;
+	}
+	count = min((int)count, DS2780_DATA_SIZE - addr);
+
+	if (w1_reset_select_slave(sl) == 0) {
+		if (io) {
+			w1_write_8(sl->master, W1_DS2780_WRITE_DATA);
+			w1_write_8(sl->master, addr);
+			w1_write_block(sl->master, buf, count);
+			/* XXX w1_write_block returns void, not n_written */
+		} else {
+			w1_write_8(sl->master, W1_DS2780_READ_DATA);
+			w1_write_8(sl->master, addr);
+			count = w1_read_block(sl->master, buf, count);
+		}
+	}
+
+out:
+	mutex_unlock(&sl->master->mutex);
+
+	return count;
+}
+EXPORT_SYMBOL(w1_ds2780_io);
+
+int w1_ds2780_eeprom_cmd(struct device *dev, int addr, int cmd)
+{
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+
+	if (!dev)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->mutex);
+
+	if (w1_reset_select_slave(sl) == 0) {
+		w1_write_8(sl->master, cmd);
+		w1_write_8(sl->master, addr);
+	}
+
+	mutex_unlock(&sl->master->mutex);
+	return 0;
+}
+EXPORT_SYMBOL(w1_ds2780_eeprom_cmd);
+
+static ssize_t w1_ds2780_read_bin(struct file *filp,
+				  struct kobject *kobj,
+				  struct bin_attribute *bin_attr,
+				  char *buf, loff_t off, size_t count)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	return w1_ds2780_io(dev, buf, off, count, 0);
+}
+
+static struct bin_attribute w1_ds2780_bin_attr = {
+	.attr = {
+		.name = "w1_slave",
+		.mode = S_IRUGO,
+	},
+	.size = DS2780_DATA_SIZE,
+	.read = w1_ds2780_read_bin,
+};
+
+static DEFINE_IDR(bat_idr);
+static DEFINE_MUTEX(bat_idr_lock);
+
+static int new_bat_id(void)
+{
+	int ret;
+
+	while (1) {
+		int id;
+
+		ret = idr_pre_get(&bat_idr, GFP_KERNEL);
+		if (ret == 0)
+			return -ENOMEM;
+
+		mutex_lock(&bat_idr_lock);
+		ret = idr_get_new(&bat_idr, NULL, &id);
+		mutex_unlock(&bat_idr_lock);
+
+		if (ret == 0) {
+			ret = id & MAX_ID_MASK;
+			break;
+		} else if (ret == -EAGAIN) {
+			continue;
+		} else {
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void release_bat_id(int id)
+{
+	mutex_lock(&bat_idr_lock);
+	idr_remove(&bat_idr, id);
+	mutex_unlock(&bat_idr_lock);
+}
+
+static int w1_ds2780_add_slave(struct w1_slave *sl)
+{
+	int ret;
+	int id;
+	struct platform_device *pdev;
+
+	id = new_bat_id();
+	if (id < 0) {
+		ret = id;
+		goto noid;
+	}
+
+	pdev = platform_device_alloc("ds2780-battery", id);
+	if (!pdev) {
+		ret = -ENOMEM;
+		goto pdev_alloc_failed;
+	}
+	pdev->dev.parent = &sl->dev;
+
+	ret = platform_device_add(pdev);
+	if (ret)
+		goto pdev_add_failed;
+
+	ret = sysfs_create_bin_file(&sl->dev.kobj, &w1_ds2780_bin_attr);
+	if (ret)
+		goto bin_attr_failed;
+
+	dev_set_drvdata(&sl->dev, pdev);
+
+	return 0;
+
+bin_attr_failed:
+pdev_add_failed:
+	platform_device_unregister(pdev);
+pdev_alloc_failed:
+	release_bat_id(id);
+noid:
+	return ret;
+}
+
+static void w1_ds2780_remove_slave(struct w1_slave *sl)
+{
+	struct platform_device *pdev = dev_get_drvdata(&sl->dev);
+	int id = pdev->id;
+
+	platform_device_unregister(pdev);
+	release_bat_id(id);
+	sysfs_remove_bin_file(&sl->dev.kobj, &w1_ds2780_bin_attr);
+}
+
+static struct w1_family_ops w1_ds2780_fops = {
+	.add_slave    = w1_ds2780_add_slave,
+	.remove_slave = w1_ds2780_remove_slave,
+};
+
+static struct w1_family w1_ds2780_family = {
+	.fid = W1_FAMILY_DS2780,
+	.fops = &w1_ds2780_fops,
+};
+
+static int __init w1_ds2780_init(void)
+{
+	idr_init(&bat_idr);
+	return w1_register_family(&w1_ds2780_family);
+}
+
+static void __exit w1_ds2780_exit(void)
+{
+	w1_unregister_family(&w1_ds2780_family);
+	idr_destroy(&bat_idr);
+}
+
+module_init(w1_ds2780_init);
+module_exit(w1_ds2780_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Clifton Barnes <cabarnes@indesign-llc.com>");
+MODULE_DESCRIPTION("1-wire Driver for Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC");
diff --git a/drivers/w1/slaves/w1_ds2780.h b/drivers/w1/slaves/w1_ds2780.h
new file mode 100644
index 0000000..a1fba79
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2780.h
@@ -0,0 +1,129 @@
+/*
+ * 1-Wire implementation for the ds2780 chip
+ *
+ * Copyright (C) 2010 Indesign, LLC
+ *
+ * Author: Clifton Barnes <cabarnes@indesign-llc.com>
+ *
+ * Based on w1-ds2760 driver
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef _W1_DS2780_H
+#define _W1_DS2780_H
+
+/* Function commands */
+#define W1_DS2780_READ_DATA		0x69
+#define W1_DS2780_WRITE_DATA		0x6C
+#define W1_DS2780_COPY_DATA		0x48
+#define W1_DS2780_RECALL_DATA		0xB8
+#define W1_DS2780_LOCK			0x6A
+
+/* Register map */
+/* Register 0x00 Reserved */
+#define DS2780_STATUS_REG		0x01
+#define DS2780_RAAC_MSB_REG		0x02
+#define DS2780_RAAC_LSB_REG		0x03
+#define DS2780_RSAC_MSB_REG		0x04
+#define DS2780_RSAC_LSB_REG		0x05
+#define DS2780_RARC_REG			0x06
+#define DS2780_RSRC_REG			0x07
+#define DS2780_IAVG_MSB_REG		0x08
+#define DS2780_IAVG_LSB_REG		0x09
+#define DS2780_TEMP_MSB_REG		0x0A
+#define DS2780_TEMP_LSB_REG		0x0B
+#define DS2780_VOLT_MSB_REG		0x0C
+#define DS2780_VOLT_LSB_REG		0x0D
+#define DS2780_CURRENT_MSB_REG		0x0E
+#define DS2780_CURRENT_LSB_REG		0x0F
+#define DS2780_ACR_MSB_REG		0x10
+#define DS2780_ACR_LSB_REG		0x11
+#define DS2780_ACRL_MSB_REG		0x12
+#define DS2780_ACRL_LSB_REG		0x13
+#define DS2780_AS_REG			0x14
+#define DS2780_SFR_REG			0x15
+#define DS2780_FULL_MSB_REG		0x16
+#define DS2780_FULL_LSB_REG		0x17
+#define DS2780_AE_MSB_REG		0x18
+#define DS2780_AE_LSB_REG		0x19
+#define DS2780_SE_MSB_REG		0x1A
+#define DS2780_SE_LSB_REG		0x1B
+/* Register 0x1C - 0x1E Reserved */
+#define DS2780_EEPROM_REG		0x1F
+#define DS2780_EEPROM_BLOCK0_START	0x20
+/* Register 0x20 - 0x2F User EEPROM */
+#define DS2780_EEPROM_BLOCK0_END	0x2F
+/* Register 0x30 - 0x5F Reserved */
+#define DS2780_EEPROM_BLOCK1_START	0x60
+#define DS2780_CONTROL_REG		0x60
+#define DS2780_AB_REG			0x61
+#define DS2780_AC_MSB_REG		0x62
+#define DS2780_AC_LSB_REG		0x63
+#define DS2780_VCHG_REG			0x64
+#define DS2780_IMIN_REG			0x65
+#define DS2780_VAE_REG			0x66
+#define DS2780_IAE_REG			0x67
+#define DS2780_AE_40_REG		0x68
+#define DS2780_RSNSP_REG		0x69
+#define DS2780_FULL_40_MSB_REG		0x6A
+#define DS2780_FULL_40_LSB_REG		0x6B
+#define DS2780_FULL_3040_SLOPE_REG	0x6C
+#define DS2780_FULL_2030_SLOPE_REG	0x6D
+#define DS2780_FULL_1020_SLOPE_REG	0x6E
+#define DS2780_FULL_0010_SLOPE_REG	0x6F
+#define DS2780_AE_3040_SLOPE_REG	0x70
+#define DS2780_AE_2030_SLOPE_REG	0x71
+#define DS2780_AE_1020_SLOPE_REG	0x72
+#define DS2780_AE_0010_SLOPE_REG	0x73
+#define DS2780_SE_3040_SLOPE_REG	0x74
+#define DS2780_SE_2030_SLOPE_REG	0x75
+#define DS2780_SE_1020_SLOPE_REG	0x76
+#define DS2780_SE_0010_SLOPE_REG	0x77
+#define DS2780_RSGAIN_MSB_REG		0x78
+#define DS2780_RSGAIN_LSB_REG		0x79
+#define DS2780_RSTC_REG			0x7A
+#define DS2780_FRSGAIN_MSB_REG		0x7B
+#define DS2780_FRSGAIN_LSB_REG		0x7C
+#define DS2780_EEPROM_BLOCK1_END	0x7C
+/* Register 0x7D - 0xFF Reserved */
+
+/* Number of valid register addresses */
+#define DS2780_DATA_SIZE		0x80
+
+/* Status register bits */
+#define DS2780_STATUS_REG_CHGTF		(1 << 7)
+#define DS2780_STATUS_REG_AEF		(1 << 6)
+#define DS2780_STATUS_REG_SEF		(1 << 5)
+#define DS2780_STATUS_REG_LEARNF	(1 << 4)
+/* Bit 3 Reserved */
+#define DS2780_STATUS_REG_UVF		(1 << 2)
+#define DS2780_STATUS_REG_PORF		(1 << 1)
+/* Bit 0 Reserved */
+
+/* Control register bits */
+/* Bit 7 Reserved */
+#define DS2780_CONTROL_REG_UVEN		(1 << 6)
+#define DS2780_CONTROL_REG_PMOD		(1 << 5)
+#define DS2780_CONTROL_REG_RNAOP	(1 << 4)
+/* Bit 0 - 3 Reserved */
+
+/* Special feature register bits */
+/* Bit 1 - 7 Reserved */
+#define DS2780_SFR_REG_PIOSC		(1 << 0)
+
+/* EEPROM register bits */
+#define DS2780_EEPROM_REG_EEC		(1 << 7)
+#define DS2780_EEPROM_REG_LOCK		(1 << 6)
+/* Bit 2 - 6 Reserved */
+#define DS2780_EEPROM_REG_BL1		(1 << 1)
+#define DS2780_EEPROM_REG_BL0		(1 << 0)
+
+extern int w1_ds2780_io(struct device *dev, char *buf, int addr, size_t count,
+			int io);
+extern int w1_ds2780_eeprom_cmd(struct device *dev, int addr, int cmd);
+
+#endif /* !_W1_DS2780_H */
diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
index f3b636d..e76125c 100644
--- a/drivers/w1/w1_family.h
+++ b/drivers/w1/w1_family.h
@@ -36,6 +36,7 @@
 #define W1_THERM_DS18B20 	0x28
 #define W1_EEPROM_DS2431	0x2D
 #define W1_FAMILY_DS2760	0x30
+#define W1_FAMILY_DS2780	0x32
 
 #define MAXNAMELEN		32
 
-- 
1.7.3.4