[14/15] power: supply: Add driver for Cherry Trail Whiskey Cove PMIC Fuel Gauge

Submitted by Hans de Goede on March 17, 2017, 9:55 a.m.

Details

Message ID 20170317095527.10487-15-hdegoede@redhat.com
State New
Headers show

Commit Message

Hans de Goede March 17, 2017, 9:55 a.m.
Add a driver for the Cherry Trail Whiskey Cove PMIC Fuel Gauge, note
the Cherry Trail Whiskey Cove PMIC Fuel Gauge block is purely a fuel gauge
and not a full battery controller. As such it offers a platform_data
callback for extra power_supply properties for the actual external-charger
ic driver and does not register a power_supply itself.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/power/supply/Kconfig             |   9 ++
 drivers/power/supply/Makefile            |   1 +
 drivers/power/supply/cht_wc_fuel_gauge.c | 209 +++++++++++++++++++++++++++++++
 include/linux/power/cht_wc_fuel_gauge.h  |  21 ++++
 4 files changed, 240 insertions(+)
 create mode 100644 drivers/power/supply/cht_wc_fuel_gauge.c
 create mode 100644 include/linux/power/cht_wc_fuel_gauge.h

Comments

Andy Shevchenko March 17, 2017, 5:58 p.m.
On Fri, 2017-03-17 at 10:55 +0100, Hans de Goede wrote:
> Add a driver for the Cherry Trail Whiskey Cove PMIC Fuel Gauge, note
> the Cherry Trail Whiskey Cove PMIC Fuel Gauge block is purely a fuel
> gauge
> and not a full battery controller. As such it offers a platform_data
> callback for extra power_supply properties for the actual external-
> charger
> ic driver and does not register a power_supply itself.

ic -> IC

Can we move to something like built-in device properties for additional
properties instead of extending platform data?

> +config CHT_WC_FUEL_GAUGE

I would use similar pattern:

FUEL_GAUGE_INTEL_CHTWC (or FUEL_GAUGE_CHTWC, but this might be less
obvious about vendor)

> --- /dev/null
> +++ b/drivers/power/supply/cht_wc_fuel_gauge.c
> @@ -0,0 +1,209 @@
> +/*
> + * Intel CHT Whiskey Cove Fuel Gauge driver

CHT -> Cherry Trail 

> + *
> + * Cherrytrail Whiskey Cove devices have 2 functional blocks which
> interact
> + * with the battery.

Cherry Trail? 

> +#define REG_CHARGE_NOW		0x05
> +#define REG_VOLTAGE_NOW		0x09
> +#define REG_CURRENT_NOW		0x0a
> +#define REG_CURRENT_AVG		0x0b
> +#define REG_CHARGE_FULL		0x10
> +#define REG_CHARGE_DESIGN	0x18
> +#define REG_VOLTAGE_AVG		0x19

> +#define REG_VOLTAGE_OCV		0x1b /* Only updated during
> charging */

I think comment makes more sense where actual update is happening in the
code.

> +
> +static int cht_wc_fg_read(struct cht_wc_fg_data *fg, u8 reg,
> +			  union power_supply_propval *val, int scale,
> +			  int sign_extend)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_word_data(fg->client, reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (sign_extend)
> +		ret = sign_extend32(ret, 15);

Magic?

> +
> +	val->intval = ret * scale;
> +
> +	return 0;
> +}


> +
> +int cht_wc_fg_get_property(enum power_supply_property prop,
> +			   union power_supply_propval *val)
> +{
> +	int ret = 0;

Sounds like redundant assignment...

> +
> +	mutex_lock(&cht_wc_fg_mutex);
> +
> 

> +	if (!cht_wc_fg) {
> +		ret = -ENXIO;
> +		goto out_unlock;
> +	}

...otherwise maybe

ret = cht_wc_fg ? 0 : -ENXIO;
if (ret)
 goto ...;

?

> +	default:
> +		ret = -ENODATA;
> +	}
> +out_unlock:
> +	mutex_unlock(&cht_wc_fg_mutex);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cht_wc_fg_get_property);

> +
> +static int cht_wc_fg_probe(struct i2c_client *client,
> +			const struct i2c_device_id *i2c_id)
> +{
> +	struct device *dev = &client->dev;
> +	struct cht_wc_fg_data *fg;
> +	acpi_status status;
> +	unsigned long long ptyp;

> +	status = acpi_evaluate_integer(ACPI_HANDLE(dev), "PTYP",
> NULL, &ptyp);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(dev, "Failed to get PTYPE\n");
> +		return -ENODEV;
> +	}
> +
> +	/*
> +	 * The same ACPI HID is used with different PMICs check PTYP
> to
> +	 * ensure that we are dealing with a Whiskey Cove PMIC.
> +	 */
> +	if (ptyp != CHT_WC_FG_PTYPE)
> +		return -ENODEV;

Logically I would split this part to be a main driver for device which
would use actual driver based on this, though I think it too much churn
for no benefit right now.

> +	mutex_lock(&cht_wc_fg_mutex);
> +	cht_wc_fg = fg;
> +	mutex_unlock(&cht_wc_fg_mutex);

It's pity we have no common storage of single possible present device
drivers in the kernel. I would use some kind of framework rather then
keeping all those global variables with locking. Perhaps radix / RB
tree.

> +
> +	return 0;
> +}
Sebastian Reichel March 20, 2017, 5:07 a.m.
Hi,

On Fri, Mar 17, 2017 at 10:55:26AM +0100, Hans de Goede wrote:
> Add a driver for the Cherry Trail Whiskey Cove PMIC Fuel Gauge, note
> the Cherry Trail Whiskey Cove PMIC Fuel Gauge block is purely a fuel gauge
> and not a full battery controller. As such it offers a platform_data
> callback for extra power_supply properties for the actual external-charger
> ic driver and does not register a power_supply itself.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

I think this should become a normal battery-type power-supply
driver. bq24190_charger driver should only expose a charger-type
power-supply device on your system (and probably most others, its
very rare, that systems have a programmable charger and no
fuel-gauge).

-- Sebastian

> ---
>  drivers/power/supply/Kconfig             |   9 ++
>  drivers/power/supply/Makefile            |   1 +
>  drivers/power/supply/cht_wc_fuel_gauge.c | 209 +++++++++++++++++++++++++++++++
>  include/linux/power/cht_wc_fuel_gauge.h  |  21 ++++
>  4 files changed, 240 insertions(+)
>  create mode 100644 drivers/power/supply/cht_wc_fuel_gauge.c
>  create mode 100644 include/linux/power/cht_wc_fuel_gauge.h
> 
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index fd93110..34ebfca 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -538,4 +538,13 @@ config AXP20X_POWER
>  	  This driver provides support for the power supply features of
>  	  AXP20x PMIC.
>  
> +config CHT_WC_FUEL_GAUGE
> +	tristate "Intel Cherry Trail Whiskey Cove PMIC Fuel Gauge"
> +	depends on INTEL_SOC_PMIC_CHTWC
> +	help
> +	  This adds support for the battery fuel gauge found in the Intel
> +	  Cherry Trail Whiskey Cove PMIC. This driver allows monitoring
> +	  of the charge level of the battery on Intel Cherry Trail systems
> +	  with a Whiskey Cove PMIC.
> +
>  endif # POWER_SUPPLY
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index 3789a2c..702e28a 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -74,3 +74,4 @@ obj-$(CONFIG_CHARGER_TPS65090)	+= tps65090-charger.o
>  obj-$(CONFIG_CHARGER_TPS65217)	+= tps65217_charger.o
>  obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
>  obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
> +obj-$(CONFIG_CHT_WC_FUEL_GAUGE)	+= cht_wc_fuel_gauge.o
> diff --git a/drivers/power/supply/cht_wc_fuel_gauge.c b/drivers/power/supply/cht_wc_fuel_gauge.c
> new file mode 100644
> index 0000000..56f6e5a
> --- /dev/null
> +++ b/drivers/power/supply/cht_wc_fuel_gauge.c
> @@ -0,0 +1,209 @@
> +/*
> + * Intel CHT Whiskey Cove Fuel Gauge driver
> + * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * Cherrytrail Whiskey Cove devices have 2 functional blocks which interact
> + * with the battery.
> + *
> + * 1) The fuel-gauge which is build into the Whiskey Cove PMIC, but has its
> + * own i2c bus and i2c client addresses separately from the rest of the PMIC.
> + * That block is what this driver is for.
> + *
> + * 2) An external charger IC, which is connected to the SMBUS controller
> + * which is part of the rest of the Whiskey Cove PMIC, mfd/intel_cht_wc.c
> + * registers a platform device for the SMBUS controller and
> + * i2c/busses/i2c-cht-wc.c contains the i2c-adapter driver for this.
> + *
> + * However we want to present this as a single power_supply device to
> + * userspace. So this driver offers a callback to get the fuel-gauge
> + * power_supply properties, which gets passed to the external charger
> + * driver via i2c_board_info when i2c-cht-wc.c calls i2c_new_device().
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/intel_soc_pmic.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/power/cht_wc_fuel_gauge.h>
> +#include <linux/slab.h>
> +
> +#define REG_CHARGE_NOW		0x05
> +#define REG_VOLTAGE_NOW		0x09
> +#define REG_CURRENT_NOW		0x0a
> +#define REG_CURRENT_AVG		0x0b
> +#define REG_CHARGE_FULL		0x10
> +#define REG_CHARGE_DESIGN	0x18
> +#define REG_VOLTAGE_AVG		0x19
> +#define REG_VOLTAGE_OCV		0x1b /* Only updated during charging */
> +
> +#define CHT_WC_FG_PTYPE		4
> +
> +struct cht_wc_fg_data {
> +	struct device *dev;
> +	struct i2c_client *client;
> +};
> +
> +static DEFINE_MUTEX(cht_wc_fg_mutex);
> +static struct cht_wc_fg_data *cht_wc_fg;
> +
> +static int cht_wc_fg_read(struct cht_wc_fg_data *fg, u8 reg,
> +			  union power_supply_propval *val, int scale,
> +			  int sign_extend)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_word_data(fg->client, reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (sign_extend)
> +		ret = sign_extend32(ret, 15);
> +
> +	val->intval = ret * scale;
> +
> +	return 0;
> +}
> +
> +int cht_wc_fg_get_property(enum power_supply_property prop,
> +			   union power_supply_propval *val)
> +{
> +	int ret = 0;
> +
> +	mutex_lock(&cht_wc_fg_mutex);
> +
> +	if (!cht_wc_fg) {
> +		ret = -ENXIO;
> +		goto out_unlock;
> +	}
> +
> +	switch (prop) {
> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_NOW, val, 75, 0);
> +		break;
> +	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_AVG, val, 75, 0);
> +		break;
> +	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_OCV, val, 75, 0);
> +		break;
> +	case POWER_SUPPLY_PROP_CURRENT_NOW:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_CURRENT_NOW, val, 150, 1);
> +		break;
> +	case POWER_SUPPLY_PROP_CURRENT_AVG:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_CURRENT_AVG, val, 150, 1);
> +		break;
> +	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_DESIGN, val, 500, 0);
> +		break;
> +	case POWER_SUPPLY_PROP_CHARGE_FULL:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_FULL, val, 500, 0);
> +		break;
> +	case POWER_SUPPLY_PROP_CHARGE_NOW:
> +		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_NOW, val, 500, 0);
> +		break;
> +	default:
> +		ret = -ENODATA;
> +	}
> +out_unlock:
> +	mutex_unlock(&cht_wc_fg_mutex);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cht_wc_fg_get_property);
> +
> +static int cht_wc_fg_probe(struct i2c_client *client,
> +			const struct i2c_device_id *i2c_id)
> +{
> +	struct device *dev = &client->dev;
> +	struct cht_wc_fg_data *fg;
> +	acpi_status status;
> +	unsigned long long ptyp;
> +
> +	fg = devm_kzalloc(dev, sizeof(*fg), GFP_KERNEL);
> +	if (!fg)
> +		return -ENOMEM;
> +
> +	status = acpi_evaluate_integer(ACPI_HANDLE(dev), "PTYP", NULL, &ptyp);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(dev, "Failed to get PTYPE\n");
> +		return -ENODEV;
> +	}
> +
> +	/*
> +	 * The same ACPI HID is used with different PMICs check PTYP to
> +	 * ensure that we are dealing with a Whiskey Cove PMIC.
> +	 */
> +	if (ptyp != CHT_WC_FG_PTYPE)
> +		return -ENODEV;
> +
> +	fg->dev = dev;
> +	/*
> +	 * The current resource settings table for the fuel gauge contains
> +	 * multiple i2c devices on 2 different i2c-busses. The one we actually
> +	 * want is the second resource (index 1).
> +	 */
> +	fg->client = i2c_acpi_new_device(dev, 1);
> +	if (!fg->client)
> +		return -EPROBE_DEFER;
> +
> +	i2c_set_clientdata(client, fg);
> +
> +	mutex_lock(&cht_wc_fg_mutex);
> +	cht_wc_fg = fg;
> +	mutex_unlock(&cht_wc_fg_mutex);
> +
> +	return 0;
> +}
> +
> +static int cht_wc_fg_remove(struct i2c_client *i2c)
> +{
> +	struct cht_wc_fg_data *fg = i2c_get_clientdata(i2c);
> +
> +	mutex_lock(&cht_wc_fg_mutex);
> +	cht_wc_fg = NULL;
> +	mutex_unlock(&cht_wc_fg_mutex);
> +
> +	i2c_unregister_device(fg->client);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id cht_wc_fg_i2c_id[] = {
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, cht_wc_fg_i2c_id);
> +
> +static const struct acpi_device_id cht_wc_fg_acpi_ids[] = {
> +	{ "INT33FE", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, cht_wc_fg_acpi_ids);
> +
> +static struct i2c_driver cht_wc_fg_driver = {
> +	.driver	= {
> +		.name	= "CHT Whiskey Cove PMIC Fuel Gauge",
> +		.acpi_match_table = ACPI_PTR(cht_wc_fg_acpi_ids),
> +	},
> +	.probe = cht_wc_fg_probe,
> +	.remove = cht_wc_fg_remove,
> +	.id_table = cht_wc_fg_i2c_id,
> +	.irq_index = 1,
> +};
> +
> +module_i2c_driver(cht_wc_fg_driver);
> +
> +MODULE_DESCRIPTION("Intel CHT Whiskey Cove PMIC Fuel Gauge driver");
> +MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/power/cht_wc_fuel_gauge.h b/include/linux/power/cht_wc_fuel_gauge.h
> new file mode 100644
> index 0000000..4b4e051
> --- /dev/null
> +++ b/include/linux/power/cht_wc_fuel_gauge.h
> @@ -0,0 +1,21 @@
> +/*
> + * Intel CHT Whiskey Cove Fuel Gauge driver
> + * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef __CHT_WC_FUEL_GAUGE_H
> +#define __CHT_WC_FUEL_GAUGE_H
> +
> +int cht_wc_fg_get_property(enum power_supply_property prop,
> +			   union power_supply_propval *val);
> +
> +#endif
> -- 
> 2.9.3
>
Hans de Goede March 22, 2017, 5:03 p.m.
Hi,

On 17-03-17 18:58, Andy Shevchenko wrote:
> On Fri, 2017-03-17 at 10:55 +0100, Hans de Goede wrote:
>> Add a driver for the Cherry Trail Whiskey Cove PMIC Fuel Gauge, note
>> the Cherry Trail Whiskey Cove PMIC Fuel Gauge block is purely a fuel
>> gauge
>> and not a full battery controller. As such it offers a platform_data
>> callback for extra power_supply properties for the actual external-
>> charger
>> ic driver and does not register a power_supply itself.
>
> ic -> IC
>
> Can we move to something like built-in device properties for additional
> properties instead of extending platform data?
>
>> +config CHT_WC_FUEL_GAUGE
>
> I would use similar pattern:
>
> FUEL_GAUGE_INTEL_CHTWC (or FUEL_GAUGE_CHTWC, but this might be less
> obvious about vendor)

Good point, although all the fuel-gauge's seem to use
BATTERY as prefix, so I've gone with that.

>
>> --- /dev/null
>> +++ b/drivers/power/supply/cht_wc_fuel_gauge.c
>> @@ -0,0 +1,209 @@
>> +/*
>> + * Intel CHT Whiskey Cove Fuel Gauge driver
>
> CHT -> Cherry Trail

Fixed.

>
>> + *
>> + * Cherrytrail Whiskey Cove devices have 2 functional blocks which
>> interact
>> + * with the battery.
>
> Cherry Trail?

Since after discussion about how to deal with the charger / fuel_gauge
comment v2 is going to be a stand-alone power_supply driver this
comment has been dropped.

>
>> +#define REG_CHARGE_NOW		0x05
>> +#define REG_VOLTAGE_NOW		0x09
>> +#define REG_CURRENT_NOW		0x0a
>> +#define REG_CURRENT_AVG		0x0b
>> +#define REG_CHARGE_FULL		0x10
>> +#define REG_CHARGE_DESIGN	0x18
>> +#define REG_VOLTAGE_AVG		0x19
>
>> +#define REG_VOLTAGE_OCV		0x1b /* Only updated during
>> charging */
>
> I think comment makes more sense where actual update is happening in the
> code.
>
>> +
>> +static int cht_wc_fg_read(struct cht_wc_fg_data *fg, u8 reg,
>> +			  union power_supply_propval *val, int scale,
>> +			  int sign_extend)
>> +{
>> +	int ret;
>> +
>> +	ret = i2c_smbus_read_word_data(fg->client, reg);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	if (sign_extend)
>> +		ret = sign_extend32(ret, 15);
>
> Magic?

Nope just simply dealing with i2c_smbus_read_word_data always
returning 16 bit unsigned data (or a negative error code)
and some of the registers being 16 bit signed.

>
>> +
>> +	val->intval = ret * scale;
>> +
>> +	return 0;
>> +}
>
>
>> +
>> +int cht_wc_fg_get_property(enum power_supply_property prop,
>> +			   union power_supply_propval *val)
>> +{
>> +	int ret = 0;
>
> Sounds like redundant assignment...

No longer redundant in v2.

>
>> +
>> +	mutex_lock(&cht_wc_fg_mutex);
>> +
>>
>
>> +	if (!cht_wc_fg) {
>> +		ret = -ENXIO;
>> +		goto out_unlock;
>> +	}
>
> ...otherwise maybe
>
> ret = cht_wc_fg ? 0 : -ENXIO;
> if (ret)
>  goto ...;
>
> ?

With the stand-alone power_supply driver version this ugliness is gone.

>
>> +	default:
>> +		ret = -ENODATA;
>> +	}
>> +out_unlock:
>> +	mutex_unlock(&cht_wc_fg_mutex);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(cht_wc_fg_get_property);
>
>> +
>> +static int cht_wc_fg_probe(struct i2c_client *client,
>> +			const struct i2c_device_id *i2c_id)
>> +{
>> +	struct device *dev = &client->dev;
>> +	struct cht_wc_fg_data *fg;
>> +	acpi_status status;
>> +	unsigned long long ptyp;
>
>> +	status = acpi_evaluate_integer(ACPI_HANDLE(dev), "PTYP",
>> NULL, &ptyp);
>> +	if (ACPI_FAILURE(status)) {
>> +		dev_err(dev, "Failed to get PTYPE\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	/*
>> +	 * The same ACPI HID is used with different PMICs check PTYP
>> to
>> +	 * ensure that we are dealing with a Whiskey Cove PMIC.
>> +	 */
>> +	if (ptyp != CHT_WC_FG_PTYPE)
>> +		return -ENODEV;
>
> Logically I would split this part to be a main driver for device which
> would use actual driver based on this, though I think it too much churn
> for no benefit right now.

Ack.

>
>> +	mutex_lock(&cht_wc_fg_mutex);
>> +	cht_wc_fg = fg;
>> +	mutex_unlock(&cht_wc_fg_mutex);
>
> It's pity we have no common storage of single possible present device
> drivers in the kernel. I would use some kind of framework rather then
> keeping all those global variables with locking. Perhaps radix / RB
> tree.

With the stand-alone power_supply driver version this ugliness is gone.

Regards,

Hans

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Patch hide | download patch | download mbox

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index fd93110..34ebfca 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -538,4 +538,13 @@  config AXP20X_POWER
 	  This driver provides support for the power supply features of
 	  AXP20x PMIC.
 
+config CHT_WC_FUEL_GAUGE
+	tristate "Intel Cherry Trail Whiskey Cove PMIC Fuel Gauge"
+	depends on INTEL_SOC_PMIC_CHTWC
+	help
+	  This adds support for the battery fuel gauge found in the Intel
+	  Cherry Trail Whiskey Cove PMIC. This driver allows monitoring
+	  of the charge level of the battery on Intel Cherry Trail systems
+	  with a Whiskey Cove PMIC.
+
 endif # POWER_SUPPLY
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 3789a2c..702e28a 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -74,3 +74,4 @@  obj-$(CONFIG_CHARGER_TPS65090)	+= tps65090-charger.o
 obj-$(CONFIG_CHARGER_TPS65217)	+= tps65217_charger.o
 obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
 obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
+obj-$(CONFIG_CHT_WC_FUEL_GAUGE)	+= cht_wc_fuel_gauge.o
diff --git a/drivers/power/supply/cht_wc_fuel_gauge.c b/drivers/power/supply/cht_wc_fuel_gauge.c
new file mode 100644
index 0000000..56f6e5a
--- /dev/null
+++ b/drivers/power/supply/cht_wc_fuel_gauge.c
@@ -0,0 +1,209 @@ 
+/*
+ * Intel CHT Whiskey Cove Fuel Gauge driver
+ * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Cherrytrail Whiskey Cove devices have 2 functional blocks which interact
+ * with the battery.
+ *
+ * 1) The fuel-gauge which is build into the Whiskey Cove PMIC, but has its
+ * own i2c bus and i2c client addresses separately from the rest of the PMIC.
+ * That block is what this driver is for.
+ *
+ * 2) An external charger IC, which is connected to the SMBUS controller
+ * which is part of the rest of the Whiskey Cove PMIC, mfd/intel_cht_wc.c
+ * registers a platform device for the SMBUS controller and
+ * i2c/busses/i2c-cht-wc.c contains the i2c-adapter driver for this.
+ *
+ * However we want to present this as a single power_supply device to
+ * userspace. So this driver offers a callback to get the fuel-gauge
+ * power_supply properties, which gets passed to the external charger
+ * driver via i2c_board_info when i2c-cht-wc.c calls i2c_new_device().
+ */
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/intel_soc_pmic.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/power/cht_wc_fuel_gauge.h>
+#include <linux/slab.h>
+
+#define REG_CHARGE_NOW		0x05
+#define REG_VOLTAGE_NOW		0x09
+#define REG_CURRENT_NOW		0x0a
+#define REG_CURRENT_AVG		0x0b
+#define REG_CHARGE_FULL		0x10
+#define REG_CHARGE_DESIGN	0x18
+#define REG_VOLTAGE_AVG		0x19
+#define REG_VOLTAGE_OCV		0x1b /* Only updated during charging */
+
+#define CHT_WC_FG_PTYPE		4
+
+struct cht_wc_fg_data {
+	struct device *dev;
+	struct i2c_client *client;
+};
+
+static DEFINE_MUTEX(cht_wc_fg_mutex);
+static struct cht_wc_fg_data *cht_wc_fg;
+
+static int cht_wc_fg_read(struct cht_wc_fg_data *fg, u8 reg,
+			  union power_supply_propval *val, int scale,
+			  int sign_extend)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(fg->client, reg);
+	if (ret < 0)
+		return ret;
+
+	if (sign_extend)
+		ret = sign_extend32(ret, 15);
+
+	val->intval = ret * scale;
+
+	return 0;
+}
+
+int cht_wc_fg_get_property(enum power_supply_property prop,
+			   union power_supply_propval *val)
+{
+	int ret = 0;
+
+	mutex_lock(&cht_wc_fg_mutex);
+
+	if (!cht_wc_fg) {
+		ret = -ENXIO;
+		goto out_unlock;
+	}
+
+	switch (prop) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_NOW, val, 75, 0);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_AVG, val, 75, 0);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_OCV, val, 75, 0);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CURRENT_NOW, val, 150, 1);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CURRENT_AVG, val, 150, 1);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_DESIGN, val, 500, 0);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_FULL, val, 500, 0);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_NOW, val, 500, 0);
+		break;
+	default:
+		ret = -ENODATA;
+	}
+out_unlock:
+	mutex_unlock(&cht_wc_fg_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cht_wc_fg_get_property);
+
+static int cht_wc_fg_probe(struct i2c_client *client,
+			const struct i2c_device_id *i2c_id)
+{
+	struct device *dev = &client->dev;
+	struct cht_wc_fg_data *fg;
+	acpi_status status;
+	unsigned long long ptyp;
+
+	fg = devm_kzalloc(dev, sizeof(*fg), GFP_KERNEL);
+	if (!fg)
+		return -ENOMEM;
+
+	status = acpi_evaluate_integer(ACPI_HANDLE(dev), "PTYP", NULL, &ptyp);
+	if (ACPI_FAILURE(status)) {
+		dev_err(dev, "Failed to get PTYPE\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * The same ACPI HID is used with different PMICs check PTYP to
+	 * ensure that we are dealing with a Whiskey Cove PMIC.
+	 */
+	if (ptyp != CHT_WC_FG_PTYPE)
+		return -ENODEV;
+
+	fg->dev = dev;
+	/*
+	 * The current resource settings table for the fuel gauge contains
+	 * multiple i2c devices on 2 different i2c-busses. The one we actually
+	 * want is the second resource (index 1).
+	 */
+	fg->client = i2c_acpi_new_device(dev, 1);
+	if (!fg->client)
+		return -EPROBE_DEFER;
+
+	i2c_set_clientdata(client, fg);
+
+	mutex_lock(&cht_wc_fg_mutex);
+	cht_wc_fg = fg;
+	mutex_unlock(&cht_wc_fg_mutex);
+
+	return 0;
+}
+
+static int cht_wc_fg_remove(struct i2c_client *i2c)
+{
+	struct cht_wc_fg_data *fg = i2c_get_clientdata(i2c);
+
+	mutex_lock(&cht_wc_fg_mutex);
+	cht_wc_fg = NULL;
+	mutex_unlock(&cht_wc_fg_mutex);
+
+	i2c_unregister_device(fg->client);
+
+	return 0;
+}
+
+static const struct i2c_device_id cht_wc_fg_i2c_id[] = {
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, cht_wc_fg_i2c_id);
+
+static const struct acpi_device_id cht_wc_fg_acpi_ids[] = {
+	{ "INT33FE", },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, cht_wc_fg_acpi_ids);
+
+static struct i2c_driver cht_wc_fg_driver = {
+	.driver	= {
+		.name	= "CHT Whiskey Cove PMIC Fuel Gauge",
+		.acpi_match_table = ACPI_PTR(cht_wc_fg_acpi_ids),
+	},
+	.probe = cht_wc_fg_probe,
+	.remove = cht_wc_fg_remove,
+	.id_table = cht_wc_fg_i2c_id,
+	.irq_index = 1,
+};
+
+module_i2c_driver(cht_wc_fg_driver);
+
+MODULE_DESCRIPTION("Intel CHT Whiskey Cove PMIC Fuel Gauge driver");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/power/cht_wc_fuel_gauge.h b/include/linux/power/cht_wc_fuel_gauge.h
new file mode 100644
index 0000000..4b4e051
--- /dev/null
+++ b/include/linux/power/cht_wc_fuel_gauge.h
@@ -0,0 +1,21 @@ 
+/*
+ * Intel CHT Whiskey Cove Fuel Gauge driver
+ * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __CHT_WC_FUEL_GAUGE_H
+#define __CHT_WC_FUEL_GAUGE_H
+
+int cht_wc_fg_get_property(enum power_supply_property prop,
+			   union power_supply_propval *val);
+
+#endif