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From:   Baolin Wang <baolin.wang@linaro.org>
To:     sre@kernel.org, robh+dt@kernel.org, mark.rutland@arm.com
Cc:     linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, yuanjiang.yu@unisoc.com,
        baolin.wang@linaro.org, broonie@kernel.org, ctatlor97@gmail.com,
        linus.walleij@linaro.org
Subject: [PATCH v6 6/6] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver
Date:   Mon, 22 Oct 2018 15:44:02 +0800
Message-Id: <6a4c15368e0bf34f8e6aad4d788bc899cfb9d61e.1540189330.git.baolin.wang@linaro.org>
In-Reply-To: <e7c061535f2dcca54d6498405fdd5ed7098b19f9.1540189330.git.baolin.wang@linaro.org>
References: <e7c061535f2dcca54d6498405fdd5ed7098b19f9.1540189330.git.baolin.wang@linaro.org>
In-Reply-To: <e7c061535f2dcca54d6498405fdd5ed7098b19f9.1540189330.git.baolin.wang@linaro.org>
References: <e7c061535f2dcca54d6498405fdd5ed7098b19f9.1540189330.git.baolin.wang@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This patch adds the Spreadtrum SC27XX serial PMICs fuel gauge support,
which is used to calculate the battery capacity.

Original-by: Yuanjiang Yu <yuanjiang.yu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
Changes from v5:
 - Save the OCV values in micro volts for OCV capacity table.
 - Use devm_kmemdup() instead of devm_kzalloc() in sc27xx_fgu_hw_init()

Changes from v4:
 - None.

Changes from v3:
 - None.

Changes from v2:
 - Use core helper functions to look up OCV capacity table.
 - Use device_property_read_u32() instead of of_property_read_u32().
 - Add acked tag from Linus.

Changes from v1:
 - Use battery standard properties to get internal resistance and ocv table.
 - Change devm_gpiod_get_optional() to devm_gpiod_get().
 - Add power_supply_changed() when detecting battery present change.
 - Return micro volts for sc27xx_fgu_get_vbat_ocv().
---
 drivers/power/supply/Kconfig             |    7 +
 drivers/power/supply/Makefile            |    1 +
 drivers/power/supply/sc27xx_fuel_gauge.c |  656 ++++++++++++++++++++++++++++++
 3 files changed, 664 insertions(+)
 create mode 100644 drivers/power/supply/sc27xx_fuel_gauge.c

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index f27cf07..917f4b7 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -652,4 +652,11 @@ config CHARGER_SC2731
 	 Say Y here to enable support for battery charging with SC2731
 	 PMIC chips.
 
+config FUEL_GAUGE_SC27XX
+	tristate "Spreadtrum SC27XX fuel gauge driver"
+	depends on MFD_SC27XX_PMIC || COMPILE_TEST
+	help
+	 Say Y here to enable support for fuel gauge with SC27XX
+	 PMIC chips.
+
 endif # POWER_SUPPLY
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 767105b..b731c2a 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -86,3 +86,4 @@ obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
 obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
 obj-$(CONFIG_CHARGER_CROS_USBPD)	+= cros_usbpd-charger.o
 obj-$(CONFIG_CHARGER_SC2731)	+= sc2731_charger.o
+obj-$(CONFIG_FUEL_GAUGE_SC27XX)	+= sc27xx_fuel_gauge.o
diff --git a/drivers/power/supply/sc27xx_fuel_gauge.c b/drivers/power/supply/sc27xx_fuel_gauge.c
new file mode 100644
index 0000000..4af677a
--- /dev/null
+++ b/drivers/power/supply/sc27xx_fuel_gauge.c
@@ -0,0 +1,656 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Spreadtrum Communications Inc.
+
+#include <linux/gpio/consumer.h>
+#include <linux/iio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/regmap.h>
+
+/* PMIC global control registers definition */
+#define SC27XX_MODULE_EN0		0xc08
+#define SC27XX_CLK_EN0			0xc18
+#define SC27XX_FGU_EN			BIT(7)
+#define SC27XX_FGU_RTC_EN		BIT(6)
+
+/* FGU registers definition */
+#define SC27XX_FGU_START		0x0
+#define SC27XX_FGU_CONFIG		0x4
+#define SC27XX_FGU_ADC_CONFIG		0x8
+#define SC27XX_FGU_STATUS		0xc
+#define SC27XX_FGU_INT_EN		0x10
+#define SC27XX_FGU_INT_CLR		0x14
+#define SC27XX_FGU_INT_STS		0x1c
+#define SC27XX_FGU_VOLTAGE		0x20
+#define SC27XX_FGU_OCV			0x24
+#define SC27XX_FGU_POCV			0x28
+#define SC27XX_FGU_CURRENT		0x2c
+#define SC27XX_FGU_CLBCNT_SETH		0x50
+#define SC27XX_FGU_CLBCNT_SETL		0x54
+#define SC27XX_FGU_CLBCNT_VALH		0x68
+#define SC27XX_FGU_CLBCNT_VALL		0x6c
+#define SC27XX_FGU_CLBCNT_QMAXL		0x74
+
+#define SC27XX_WRITE_SELCLB_EN		BIT(0)
+#define SC27XX_FGU_CLBCNT_MASK		GENMASK(15, 0)
+#define SC27XX_FGU_CLBCNT_SHIFT		16
+
+#define SC27XX_FGU_1000MV_ADC		686
+#define SC27XX_FGU_1000MA_ADC		1372
+#define SC27XX_FGU_CUR_BASIC_ADC	8192
+#define SC27XX_FGU_SAMPLE_HZ		2
+
+/*
+ * struct sc27xx_fgu_data: describe the FGU device
+ * @regmap: regmap for register access
+ * @dev: platform device
+ * @battery: battery power supply
+ * @base: the base offset for the controller
+ * @lock: protect the structure
+ * @gpiod: GPIO for battery detection
+ * @channel: IIO channel to get battery temperature
+ * @internal_resist: the battery internal resistance in mOhm
+ * @total_cap: the total capacity of the battery in mAh
+ * @init_cap: the initial capacity of the battery in mAh
+ * @init_clbcnt: the initial coulomb counter
+ * @max_volt: the maximum constant input voltage in millivolt
+ * @table_len: the capacity table length
+ * @cap_table: capacity table with corresponding ocv
+ */
+struct sc27xx_fgu_data {
+	struct regmap *regmap;
+	struct device *dev;
+	struct power_supply *battery;
+	u32 base;
+	struct mutex lock;
+	struct gpio_desc *gpiod;
+	struct iio_channel *channel;
+	bool bat_present;
+	int internal_resist;
+	int total_cap;
+	int init_cap;
+	int init_clbcnt;
+	int max_volt;
+	int table_len;
+	struct power_supply_battery_ocv_table *cap_table;
+};
+
+static const char * const sc27xx_charger_supply_name[] = {
+	"sc2731_charger",
+	"sc2720_charger",
+	"sc2721_charger",
+	"sc2723_charger",
+};
+
+static int sc27xx_fgu_adc_to_current(int adc)
+{
+	return (adc * 1000) / SC27XX_FGU_1000MA_ADC;
+}
+
+static int sc27xx_fgu_adc_to_voltage(int adc)
+{
+	return (adc * 1000) / SC27XX_FGU_1000MV_ADC;
+}
+
+/*
+ * When system boots on, we can not read battery capacity from coulomb
+ * registers, since now the coulomb registers are invalid. So we should
+ * calculate the battery open circuit voltage, and get current battery
+ * capacity according to the capacity table.
+ */
+static int sc27xx_fgu_get_boot_capacity(struct sc27xx_fgu_data *data, int *cap)
+{
+	int volt, cur, oci, ocv, ret;
+
+	/*
+	 * After system booting on, the SC27XX_FGU_CLBCNT_QMAXL register saved
+	 * the first sampled open circuit current.
+	 */
+	ret = regmap_read(data->regmap, data->base + SC27XX_FGU_CLBCNT_QMAXL,
+			  &cur);
+	if (ret)
+		return ret;
+
+	cur <<= 1;
+	oci = sc27xx_fgu_adc_to_current(cur - SC27XX_FGU_CUR_BASIC_ADC);
+
+	/*
+	 * Should get the OCV from SC27XX_FGU_POCV register at the system
+	 * beginning. It is ADC values reading from registers which need to
+	 * convert the corresponding voltage.
+	 */
+	ret = regmap_read(data->regmap, data->base + SC27XX_FGU_POCV, &volt);
+	if (ret)
+		return ret;
+
+	volt = sc27xx_fgu_adc_to_voltage(volt);
+	ocv = volt * 1000 - oci * data->internal_resist;
+
+	/*
+	 * Parse the capacity table to look up the correct capacity percent
+	 * according to current battery's corresponding OCV values.
+	 */
+	*cap = power_supply_ocv2cap_simple(data->cap_table, data->table_len,
+					   ocv);
+
+	return 0;
+}
+
+static int sc27xx_fgu_set_clbcnt(struct sc27xx_fgu_data *data, int clbcnt)
+{
+	int ret;
+
+	clbcnt *= SC27XX_FGU_SAMPLE_HZ;
+
+	ret = regmap_update_bits(data->regmap,
+				 data->base + SC27XX_FGU_CLBCNT_SETL,
+				 SC27XX_FGU_CLBCNT_MASK, clbcnt);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(data->regmap,
+				 data->base + SC27XX_FGU_CLBCNT_SETH,
+				 SC27XX_FGU_CLBCNT_MASK,
+				 clbcnt >> SC27XX_FGU_CLBCNT_SHIFT);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(data->regmap, data->base + SC27XX_FGU_START,
+				 SC27XX_WRITE_SELCLB_EN,
+				 SC27XX_WRITE_SELCLB_EN);
+}
+
+static int sc27xx_fgu_get_clbcnt(struct sc27xx_fgu_data *data, int *clb_cnt)
+{
+	int ccl, cch, ret;
+
+	ret = regmap_read(data->regmap, data->base + SC27XX_FGU_CLBCNT_VALL,
+			  &ccl);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(data->regmap, data->base + SC27XX_FGU_CLBCNT_VALH,
+			  &cch);
+	if (ret)
+		return ret;
+
+	*clb_cnt = ccl & SC27XX_FGU_CLBCNT_MASK;
+	*clb_cnt |= (cch & SC27XX_FGU_CLBCNT_MASK) << SC27XX_FGU_CLBCNT_SHIFT;
+	*clb_cnt /= SC27XX_FGU_SAMPLE_HZ;
+
+	return 0;
+}
+
+static int sc27xx_fgu_get_capacity(struct sc27xx_fgu_data *data, int *cap)
+{
+	int ret, cur_clbcnt, delta_clbcnt, delta_cap, temp;
+
+	/* Get current coulomb counters firstly */
+	ret = sc27xx_fgu_get_clbcnt(data, &cur_clbcnt);
+	if (ret)
+		return ret;
+
+	delta_clbcnt = cur_clbcnt - data->init_clbcnt;
+
+	/*
+	 * Convert coulomb counter to delta capacity (mAh), and set multiplier
+	 * as 100 to improve the precision.
+	 */
+	temp = DIV_ROUND_CLOSEST(delta_clbcnt, 360);
+	temp = sc27xx_fgu_adc_to_current(temp);
+
+	/*
+	 * Convert to capacity percent of the battery total capacity,
+	 * and multiplier is 100 too.
+	 */
+	delta_cap = DIV_ROUND_CLOSEST(temp * 100, data->total_cap);
+	*cap = delta_cap + data->init_cap;
+
+	return 0;
+}
+
+static int sc27xx_fgu_get_vbat_vol(struct sc27xx_fgu_data *data, int *val)
+{
+	int ret, vol;
+
+	ret = regmap_read(data->regmap, data->base + SC27XX_FGU_VOLTAGE, &vol);
+	if (ret)
+		return ret;
+
+	/*
+	 * It is ADC values reading from registers which need to convert to
+	 * corresponding voltage values.
+	 */
+	*val = sc27xx_fgu_adc_to_voltage(vol);
+
+	return 0;
+}
+
+static int sc27xx_fgu_get_current(struct sc27xx_fgu_data *data, int *val)
+{
+	int ret, cur;
+
+	ret = regmap_read(data->regmap, data->base + SC27XX_FGU_CURRENT, &cur);
+	if (ret)
+		return ret;
+
+	/*
+	 * It is ADC values reading from registers which need to convert to
+	 * corresponding current values.
+	 */
+	*val = sc27xx_fgu_adc_to_current(cur - SC27XX_FGU_CUR_BASIC_ADC);
+
+	return 0;
+}
+
+static int sc27xx_fgu_get_vbat_ocv(struct sc27xx_fgu_data *data, int *val)
+{
+	int vol, cur, ret;
+
+	ret = sc27xx_fgu_get_vbat_vol(data, &vol);
+	if (ret)
+		return ret;
+
+	ret = sc27xx_fgu_get_current(data, &cur);
+	if (ret)
+		return ret;
+
+	/* Return the battery OCV in micro volts. */
+	*val = vol * 1000 - cur * data->internal_resist;
+
+	return 0;
+}
+
+static int sc27xx_fgu_get_temp(struct sc27xx_fgu_data *data, int *temp)
+{
+	return iio_read_channel_processed(data->channel, temp);
+}
+
+static int sc27xx_fgu_get_health(struct sc27xx_fgu_data *data, int *health)
+{
+	int ret, vol;
+
+	ret = sc27xx_fgu_get_vbat_vol(data, &vol);
+	if (ret)
+		return ret;
+
+	if (vol > data->max_volt)
+		*health = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
+	else
+		*health = POWER_SUPPLY_HEALTH_GOOD;
+
+	return 0;
+}
+
+static int sc27xx_fgu_get_status(struct sc27xx_fgu_data *data, int *status)
+{
+	union power_supply_propval val;
+	struct power_supply *psy;
+	int i, ret = -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(sc27xx_charger_supply_name); i++) {
+		psy = power_supply_get_by_name(sc27xx_charger_supply_name[i]);
+		if (!psy)
+			continue;
+
+		ret = power_supply_get_property(psy, POWER_SUPPLY_PROP_STATUS,
+						&val);
+		power_supply_put(psy);
+		if (ret)
+			return ret;
+
+		*status = val.intval;
+	}
+
+	return ret;
+}
+
+static int sc27xx_fgu_get_property(struct power_supply *psy,
+				   enum power_supply_property psp,
+				   union power_supply_propval *val)
+{
+	struct sc27xx_fgu_data *data = power_supply_get_drvdata(psy);
+	int ret = 0;
+	int value;
+
+	mutex_lock(&data->lock);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		ret = sc27xx_fgu_get_status(data, &value);
+		if (ret)
+			goto error;
+
+		val->intval = value;
+		break;
+
+	case POWER_SUPPLY_PROP_HEALTH:
+		ret = sc27xx_fgu_get_health(data, &value);
+		if (ret)
+			goto error;
+
+		val->intval = value;
+		break;
+
+	case POWER_SUPPLY_PROP_PRESENT:
+		val->intval = data->bat_present;
+		break;
+
+	case POWER_SUPPLY_PROP_TEMP:
+		ret = sc27xx_fgu_get_temp(data, &value);
+		if (ret)
+			goto error;
+
+		val->intval = value;
+		break;
+
+	case POWER_SUPPLY_PROP_TECHNOLOGY:
+		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
+		break;
+
+	case POWER_SUPPLY_PROP_CAPACITY:
+		ret = sc27xx_fgu_get_capacity(data, &value);
+		if (ret)
+			goto error;
+
+		val->intval = value;
+		break;
+
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = sc27xx_fgu_get_vbat_vol(data, &value);
+		if (ret)
+			goto error;
+
+		val->intval = value * 1000;
+		break;
+
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+		ret = sc27xx_fgu_get_vbat_ocv(data, &value);
+		if (ret)
+			goto error;
+
+		val->intval = value;
+		break;
+
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		ret = sc27xx_fgu_get_current(data, &value);
+		if (ret)
+			goto error;
+
+		val->intval = value * 1000;
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+error:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static void sc27xx_fgu_external_power_changed(struct power_supply *psy)
+{
+	struct sc27xx_fgu_data *data = power_supply_get_drvdata(psy);
+
+	power_supply_changed(data->battery);
+}
+
+static enum power_supply_property sc27xx_fgu_props[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_HEALTH,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_VOLTAGE_OCV,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CURRENT_AVG,
+};
+
+static const struct power_supply_desc sc27xx_fgu_desc = {
+	.name			= "sc27xx-fgu",
+	.type			= POWER_SUPPLY_TYPE_BATTERY,
+	.properties		= sc27xx_fgu_props,
+	.num_properties		= ARRAY_SIZE(sc27xx_fgu_props),
+	.get_property		= sc27xx_fgu_get_property,
+	.external_power_changed	= sc27xx_fgu_external_power_changed,
+};
+
+static irqreturn_t sc27xx_fgu_bat_detection(int irq, void *dev_id)
+{
+	struct sc27xx_fgu_data *data = dev_id;
+	int state;
+
+	mutex_lock(&data->lock);
+
+	state = gpiod_get_value_cansleep(data->gpiod);
+	if (state < 0) {
+		dev_err(data->dev, "failed to get gpio state\n");
+		mutex_unlock(&data->lock);
+		return IRQ_RETVAL(state);
+	}
+
+	data->bat_present = !!state;
+
+	mutex_unlock(&data->lock);
+
+	power_supply_changed(data->battery);
+	return IRQ_HANDLED;
+}
+
+static void sc27xx_fgu_disable(void *_data)
+{
+	struct sc27xx_fgu_data *data = _data;
+
+	regmap_update_bits(data->regmap, SC27XX_CLK_EN0, SC27XX_FGU_RTC_EN, 0);
+	regmap_update_bits(data->regmap, SC27XX_MODULE_EN0, SC27XX_FGU_EN, 0);
+}
+
+static int sc27xx_fgu_cap_to_clbcnt(struct sc27xx_fgu_data *data, int capacity)
+{
+	/*
+	 * Get current capacity (mAh) = battery total capacity (mAh) *
+	 * current capacity percent (capacity / 100).
+	 */
+	int cur_cap = DIV_ROUND_CLOSEST(data->total_cap * capacity, 100);
+
+	/*
+	 * Convert current capacity (mAh) to coulomb counter according to the
+	 * formula: 1 mAh =3.6 coulomb.
+	 */
+	return DIV_ROUND_CLOSEST(cur_cap * 36, 10);
+}
+
+static int sc27xx_fgu_hw_init(struct sc27xx_fgu_data *data)
+{
+	struct power_supply_battery_info info = { };
+	struct power_supply_battery_ocv_table *table;
+	int ret;
+
+	ret = power_supply_get_battery_info(data->battery, &info);
+	if (ret) {
+		dev_err(data->dev, "failed to get battery information\n");
+		return ret;
+	}
+
+	data->total_cap = info.charge_full_design_uah / 1000;
+	data->max_volt = info.constant_charge_voltage_max_uv / 1000;
+	data->internal_resist = info.factory_internal_resistance_uohm / 1000;
+
+	/*
+	 * For SC27XX fuel gauge device, we only use one ocv-capacity
+	 * table in normal temperature 20 Celsius.
+	 */
+	table = power_supply_find_ocv2cap_table(&info, 20, &data->table_len);
+	if (!table)
+		return -EINVAL;
+
+	data->cap_table = devm_kmemdup(data->dev, table,
+				       data->table_len * sizeof(*table),
+				       GFP_KERNEL);
+	if (!data->cap_table) {
+		power_supply_put_battery_info(data->battery, &info);
+		return -ENOMEM;
+	}
+
+	power_supply_put_battery_info(data->battery, &info);
+
+	/* Enable the FGU module */
+	ret = regmap_update_bits(data->regmap, SC27XX_MODULE_EN0,
+				 SC27XX_FGU_EN, SC27XX_FGU_EN);
+	if (ret) {
+		dev_err(data->dev, "failed to enable fgu\n");
+		return ret;
+	}
+
+	/* Enable the FGU RTC clock to make it work */
+	ret = regmap_update_bits(data->regmap, SC27XX_CLK_EN0,
+				 SC27XX_FGU_RTC_EN, SC27XX_FGU_RTC_EN);
+	if (ret) {
+		dev_err(data->dev, "failed to enable fgu RTC clock\n");
+		goto disable_fgu;
+	}
+
+	/*
+	 * Get the boot battery capacity when system powers on, which is used to
+	 * initialize the coulomb counter. After that, we can read the coulomb
+	 * counter to measure the battery capacity.
+	 */
+	ret = sc27xx_fgu_get_boot_capacity(data, &data->init_cap);
+	if (ret) {
+		dev_err(data->dev, "failed to get boot capacity\n");
+		goto disable_clk;
+	}
+
+	/*
+	 * Convert battery capacity to the corresponding initial coulomb counter
+	 * and set into coulomb counter registers.
+	 */
+	data->init_clbcnt = sc27xx_fgu_cap_to_clbcnt(data, data->init_cap);
+	ret = sc27xx_fgu_set_clbcnt(data, data->init_clbcnt);
+	if (ret) {
+		dev_err(data->dev, "failed to initialize coulomb counter\n");
+		goto disable_clk;
+	}
+
+	return 0;
+
+disable_clk:
+	regmap_update_bits(data->regmap, SC27XX_CLK_EN0, SC27XX_FGU_RTC_EN, 0);
+disable_fgu:
+	regmap_update_bits(data->regmap, SC27XX_MODULE_EN0, SC27XX_FGU_EN, 0);
+
+	return ret;
+}
+
+static int sc27xx_fgu_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct power_supply_config fgu_cfg = { };
+	struct sc27xx_fgu_data *data;
+	int ret, irq;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!data->regmap) {
+		dev_err(&pdev->dev, "failed to get regmap\n");
+		return -ENODEV;
+	}
+
+	ret = device_property_read_u32(&pdev->dev, "reg", &data->base);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to get fgu address\n");
+		return ret;
+	}
+
+	data->channel = devm_iio_channel_get(&pdev->dev, "bat-temp");
+	if (IS_ERR(data->channel)) {
+		dev_err(&pdev->dev, "failed to get IIO channel\n");
+		return PTR_ERR(data->channel);
+	}
+
+	data->gpiod = devm_gpiod_get(&pdev->dev, "bat-detect", GPIOD_IN);
+	if (IS_ERR(data->gpiod)) {
+		dev_err(&pdev->dev, "failed to get battery detection GPIO\n");
+		return PTR_ERR(data->gpiod);
+	}
+
+	ret = gpiod_get_value_cansleep(data->gpiod);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to get gpio state\n");
+		return ret;
+	}
+
+	data->bat_present = !!ret;
+	mutex_init(&data->lock);
+	data->dev = &pdev->dev;
+
+	fgu_cfg.drv_data = data;
+	fgu_cfg.of_node = np;
+	data->battery = devm_power_supply_register(&pdev->dev, &sc27xx_fgu_desc,
+						   &fgu_cfg);
+	if (IS_ERR(data->battery)) {
+		dev_err(&pdev->dev, "failed to register power supply\n");
+		return PTR_ERR(data->battery);
+	}
+
+	ret = sc27xx_fgu_hw_init(data);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to initialize fgu hardware\n");
+		return ret;
+	}
+
+	ret = devm_add_action(&pdev->dev, sc27xx_fgu_disable, data);
+	if (ret) {
+		sc27xx_fgu_disable(data);
+		dev_err(&pdev->dev, "failed to add fgu disable action\n");
+		return ret;
+	}
+
+	irq = gpiod_to_irq(data->gpiod);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "failed to translate GPIO to IRQ\n");
+		return irq;
+	}
+
+	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
+					sc27xx_fgu_bat_detection,
+					IRQF_ONESHOT | IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING,
+					pdev->name, data);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request IRQ\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id sc27xx_fgu_of_match[] = {
+	{ .compatible = "sprd,sc2731-fgu", },
+	{ }
+};
+
+static struct platform_driver sc27xx_fgu_driver = {
+	.probe = sc27xx_fgu_probe,
+	.driver = {
+		.name = "sc27xx-fgu",
+		.of_match_table = sc27xx_fgu_of_match,
+	}
+};
+
+module_platform_driver(sc27xx_fgu_driver);
+
+MODULE_DESCRIPTION("Spreadtrum SC27XX PMICs Fual Gauge Unit Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5