[PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

[PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

[Baolin Wang]

This patch adds the binding documentation for Spreadtrum SC27XX series PMICs
fuel gauge unit device, which is used to calculate the battery capacity.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 .../devicetree/bindings/power/supply/sc27xx-fg.txt |   55 ++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt

diff --git a/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
new file mode 100644
index 0000000..7447bae
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
@@ -0,0 +1,55 @@
+Spreadtrum SC27XX PMICs Fuel Gauge Unit Power Supply Bindings
+
+Required properties:
+- compatible: Should be one of the following:
+  "sprd,sc2720-fgu",
+  "sprd,sc2721-fgu",
+  "sprd,sc2723-fgu",
+  "sprd,sc2730-fgu",
+  "sprd,sc2731-fgu".
+- reg: The address offset of fuel gauge unit.
+- bat-detect-gpio: GPIO for battery detection.
+- io-channels: Specify the IIO ADC channel to get temperature.
+- io-channel-names: Should be "bat-temp".
+- sprd,inner-resist: Specify the the battery inner resistance (mOhm).
+- sprd,ocv-cap-table: Provide the battery capacity percent with corresponding
+  open circuit voltage (ocv) of the battery, which is used to look up current
+  battery capacity according to current baterry ocv values.
+- monitored-battery: Phandle of battery characteristics devicetree node.
+  The fuel gauge uses the following battery properties:
+- charge-full-design-microamp-hours: battery design capacity.
+- constant-charge-voltage-max-microvolt: maximum constant input voltage.
+  See Documentation/devicetree/bindings/power/supply/battery.txt
+
+Example:
+
+	bat: battery {
+		compatible = "simple-battery";
+		charge-full-design-microamp-hours = <1900000>;
+		constant-charge-voltage-max-microvolt = <4350000>;
+		......
+	};
+
+	sc2731_pmic: pmic@0 {
+		compatible = "sprd,sc2731";
+		reg = <0>;
+		spi-max-frequency = <26000000>;
+		interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
+		interrupt-controller;
+		#interrupt-cells = <2>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		fgu@a00 {
+			compatible = "sprd,sc2731-fgu";
+			reg = <0xa00>;
+			bat-detect-gpio = <&pmic_eic 9 GPIO_ACTIVE_HIGH>;
+			io-channels = <&pmic_adc 5>;
+			io-channel-names = "bat-temp";
+			sprd,inner-resist = <250>;
+			sprd,ocv-cap-table = <4185 100>, <4113 95>, <4066 90>, <4022 85>, <3983 80>, <3949 75>, <3917 70>,
+				<3889 65>, <3864 60>, <3835 55>, <3805 50>, <3787 45>, <3777 40>, <3773 35>, <3770 30>,
+				<3765 25>, <3752 20>, <3724 15>, <3680 10>, <3605 5>, <3400 0>;
+			monitored-battery = <&bat>;
+		};
+	};
-- 
1.7.9.5

[PATCH 2/2] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver

[Baolin Wang]

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>
---
 drivers/power/supply/Kconfig             |    7 +
 drivers/power/supply/Makefile            |    1 +
 drivers/power/supply/sc27xx_fuel_gauge.c |  705 ++++++++++++++++++++++++++++++
 3 files changed, 713 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..4df0f47
--- /dev/null
+++ b/drivers/power/supply/sc27xx_fuel_gauge.c
@@ -0,0 +1,705 @@
+// 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_capacity_table {
+	int ocv;
+	int capacity;
+};
+
+/*
+ * 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
+ * @inner_resist: the battery inner 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 inner_resist;
+	int total_cap;
+	int init_cap;
+	int init_clbcnt;
+	int max_volt;
+	int table_len;
+	struct sc27xx_fgu_capacity_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;
+}
+
+static int sc27xx_fgu_ocv_to_capacity(struct sc27xx_fgu_data *data, int ocv)
+{
+	struct sc27xx_fgu_capacity_table *tab = data->cap_table;
+	int n = data->table_len;
+	int i, cap, tmp;
+
+	/*
+	 * Find the position in the table for current battery OCV value,
+	 * then use these two points to calculate battery capacity
+	 * according to the linear method.
+	 */
+	for (i = 0; i < n; i++)
+		if (ocv > tab[i].ocv)
+			break;
+
+	if (i > 0 && i < n) {
+		tmp = (tab[i - 1].capacity - tab[i].capacity) *
+			(ocv - tab[i].ocv) * 2;
+		tmp /= tab[i - 1].ocv - tab[i].ocv;
+		tmp = (tmp + 1) / 2;
+		cap = tmp + tab[i].capacity;
+	} else if (i == 0) {
+		cap = tab[0].capacity;
+	} else {
+		cap = tab[n - 1].capacity;
+	}
+
+	return cap;
+}
+
+/*
+ * 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 - (oci * data->inner_resist) / 1000;
+
+	/*
+	 * Parse the capacity table to look up the correct capacity percent
+	 * according to current battery's corresponding OCV values.
+	 */
+	*cap = sc27xx_fgu_ocv_to_capacity(data, 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;
+
+	*val = vol - (cur * data->inner_resist) / 1000;
+
+	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 * 1000;
+		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);
+	}
+
+	if (state)
+		data->bat_present = true;
+	else
+		data->bat_present = false;
+
+	mutex_unlock(&data->lock);
+
+	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 = { };
+	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;
+
+	/* 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_parse_dt(struct sc27xx_fgu_data *data,
+			       struct device_node *np)
+{
+	const __be32 *list;
+	int i, len, size, ret;
+
+	ret = of_property_read_u32(np, "reg", &data->base);
+	if (ret) {
+		dev_err(data->dev, "failed to get fgu address\n");
+		return ret;
+	}
+
+	data->gpiod = devm_gpiod_get_optional(data->dev, "bat-detect", GPIOD_IN);
+	if (IS_ERR(data->gpiod)) {
+		dev_err(data->dev, "failed to get battery detection GPIO\n");
+		return PTR_ERR(data->gpiod);
+	}
+
+	data->channel = devm_iio_channel_get(data->dev, "bat-temp");
+	if (IS_ERR(data->channel)) {
+		dev_err(data->dev, "failed to get IIO channel\n");
+		return PTR_ERR(data->channel);
+	}
+
+	/* Get the battery inner resistance */
+	ret = of_property_read_u32(np, "sprd,inner-resist", &data->inner_resist);
+	if (ret) {
+		dev_err(data->dev, "failed to get battery inner resistance\n");
+		return ret;
+	}
+
+	/* Get battery ocv-capacity table */
+	list = of_get_property(np, "sprd,ocv-cap-table", &size);
+	if (!list || !size) {
+		dev_err(data->dev, "failed to get ocv-capacity table\n");
+		return -EINVAL;
+	}
+
+	len = size / 8;
+	data->table_len = len;
+	data->cap_table = devm_kzalloc(data->dev,
+				sizeof(struct sc27xx_fgu_capacity_table) * len,
+				GFP_KERNEL);
+	if (!data->cap_table)
+		return -ENOMEM;
+
+	for (i = 0; i < len; i++) {
+		data->cap_table[i].ocv = be32_to_cpu(*list++);
+		data->cap_table[i].capacity = be32_to_cpu(*list++);
+	}
+
+	return 0;
+}
+
+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;
+	}
+
+	mutex_init(&data->lock);
+	data->dev = &pdev->dev;
+	data->bat_present = true;
+
+	ret = sc27xx_fgu_parse_dt(data, np);
+	if (ret)
+		return ret;
+
+	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

Re: [PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

[Sebastian Reichel]

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Hi,

On Wed, Sep 12, 2018 at 03:29:38PM +0800, Baolin Wang wrote:
> This patch adds the binding documentation for Spreadtrum SC27XX series PMICs
> fuel gauge unit device, which is used to calculate the battery capacity.
> 
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
>  .../devicetree/bindings/power/supply/sc27xx-fg.txt |   55 ++++++++++++++++++++
>  1 file changed, 55 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> 
> diff --git a/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> new file mode 100644
> index 0000000..7447bae
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> @@ -0,0 +1,55 @@
> +Spreadtrum SC27XX PMICs Fuel Gauge Unit Power Supply Bindings
> +
> +Required properties:
> +- compatible: Should be one of the following:
> +  "sprd,sc2720-fgu",
> +  "sprd,sc2721-fgu",
> +  "sprd,sc2723-fgu",
> +  "sprd,sc2730-fgu",
> +  "sprd,sc2731-fgu".
> +- reg: The address offset of fuel gauge unit.
> +- bat-detect-gpio: GPIO for battery detection.
> +- io-channels: Specify the IIO ADC channel to get temperature.
> +- io-channel-names: Should be "bat-temp".
> +- sprd,inner-resist: Specify the the battery inner resistance (mOhm).

This should be a property of the battery.without the sprd, prefix.

> +- sprd,ocv-cap-table: Provide the battery capacity percent with corresponding
> +  open circuit voltage (ocv) of the battery, which is used to look up current
> +  battery capacity according to current baterry ocv values.

This should also be part of the battery binding. I just reviewed a
patchset for the Qualcomm Battery Monitoring System, which needs the
same functionality. The Qualcomm binding is more advanced, but
should also support this simpler case. Thus I think it makes sense
to use its description as base for adding support for this feature
to Documentation/devicetree/bindings/power/supply/battery.txt

-- Sebastian

> +- monitored-battery: Phandle of battery characteristics devicetree node.
> +  The fuel gauge uses the following battery properties:
> +- charge-full-design-microamp-hours: battery design capacity.
> +- constant-charge-voltage-max-microvolt: maximum constant input voltage.
> +  See Documentation/devicetree/bindings/power/supply/battery.txt
> +
> +Example:
> +
> +	bat: battery {
> +		compatible = "simple-battery";
> +		charge-full-design-microamp-hours = <1900000>;
> +		constant-charge-voltage-max-microvolt = <4350000>;
> +		......
> +	};
> +
> +	sc2731_pmic: pmic@0 {
> +		compatible = "sprd,sc2731";
> +		reg = <0>;
> +		spi-max-frequency = <26000000>;
> +		interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
> +		interrupt-controller;
> +		#interrupt-cells = <2>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		fgu@a00 {
> +			compatible = "sprd,sc2731-fgu";
> +			reg = <0xa00>;
> +			bat-detect-gpio = <&pmic_eic 9 GPIO_ACTIVE_HIGH>;
> +			io-channels = <&pmic_adc 5>;
> +			io-channel-names = "bat-temp";
> +			sprd,inner-resist = <250>;
> +			sprd,ocv-cap-table = <4185 100>, <4113 95>, <4066 90>, <4022 85>, <3983 80>, <3949 75>, <3917 70>,
> +				<3889 65>, <3864 60>, <3835 55>, <3805 50>, <3787 45>, <3777 40>, <3773 35>, <3770 30>,
> +				<3765 25>, <3752 20>, <3724 15>, <3680 10>, <3605 5>, <3400 0>;
> +			monitored-battery = <&bat>;
> +		};
> +	};
> -- 
> 1.7.9.5
> 

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Re: [PATCH 2/2] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver

[Sebastian Reichel]

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Hi,

Looks mostly good. I have a couple of comments in addition to the
ones from the binding about using battery_info for the OCV ->
capacity mapping.

On Wed, Sep 12, 2018 at 03:29:39PM +0800, Baolin Wang wrote:
> 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>
> ---
>  drivers/power/supply/Kconfig             |    7 +
>  drivers/power/supply/Makefile            |    1 +
>  drivers/power/supply/sc27xx_fuel_gauge.c |  705 ++++++++++++++++++++++++++++++
>  3 files changed, 713 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..4df0f47
> --- /dev/null
> +++ b/drivers/power/supply/sc27xx_fuel_gauge.c
> @@ -0,0 +1,705 @@
> +// 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_capacity_table {
> +	int ocv;
> +	int capacity;
> +};
> +
> +/*
> + * 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
> + * @inner_resist: the battery inner 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 inner_resist;
> +	int total_cap;
> +	int init_cap;
> +	int init_clbcnt;
> +	int max_volt;
> +	int table_len;
> +	struct sc27xx_fgu_capacity_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;
> +}
> +
> +static int sc27xx_fgu_ocv_to_capacity(struct sc27xx_fgu_data *data, int ocv)
> +{
> +	struct sc27xx_fgu_capacity_table *tab = data->cap_table;
> +	int n = data->table_len;
> +	int i, cap, tmp;
> +
> +	/*
> +	 * Find the position in the table for current battery OCV value,
> +	 * then use these two points to calculate battery capacity
> +	 * according to the linear method.
> +	 */
> +	for (i = 0; i < n; i++)
> +		if (ocv > tab[i].ocv)
> +			break;
> +
> +	if (i > 0 && i < n) {
> +		tmp = (tab[i - 1].capacity - tab[i].capacity) *
> +			(ocv - tab[i].ocv) * 2;
> +		tmp /= tab[i - 1].ocv - tab[i].ocv;
> +		tmp = (tmp + 1) / 2;
> +		cap = tmp + tab[i].capacity;
> +	} else if (i == 0) {
> +		cap = tab[0].capacity;
> +	} else {
> +		cap = tab[n - 1].capacity;
> +	}
> +
> +	return cap;
> +}
> +
> +/*
> + * 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 - (oci * data->inner_resist) / 1000;
> +
> +	/*
> +	 * Parse the capacity table to look up the correct capacity percent
> +	 * according to current battery's corresponding OCV values.
> +	 */
> +	*cap = sc27xx_fgu_ocv_to_capacity(data, 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;
> +
> +	*val = vol - (cur * data->inner_resist) / 1000;

You multiply this with 1000 directly after this function to get back
to uV. Just drop the division and the multiplication.

> +
> +	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 * 1000;
> +		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);
> +	}
> +
> +	if (state)
> +		data->bat_present = true;
> +	else
> +		data->bat_present = false;
> +
> +	mutex_unlock(&data->lock);

You want to call power_supply_changed() here.

> +	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 = { };
> +	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;
> +
> +	/* 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_parse_dt(struct sc27xx_fgu_data *data,
> +			       struct device_node *np)
> +{
> +	const __be32 *list;
> +	int i, len, size, ret;
> +
> +	ret = of_property_read_u32(np, "reg", &data->base);
> +	if (ret) {
> +		dev_err(data->dev, "failed to get fgu address\n");
> +		return ret;
> +	}
> +
> +	data->gpiod = devm_gpiod_get_optional(data->dev, "bat-detect", GPIOD_IN);
> +	if (IS_ERR(data->gpiod)) {
> +		dev_err(data->dev, "failed to get battery detection GPIO\n");
> +		return PTR_ERR(data->gpiod);
> +	}

According to the binding (and the remaining code!) this gpio is not
optional.

-- Sebastian

> +	data->channel = devm_iio_channel_get(data->dev, "bat-temp");
> +	if (IS_ERR(data->channel)) {
> +		dev_err(data->dev, "failed to get IIO channel\n");
> +		return PTR_ERR(data->channel);
> +	}
> +
> +	/* Get the battery inner resistance */
> +	ret = of_property_read_u32(np, "sprd,inner-resist", &data->inner_resist);
> +	if (ret) {
> +		dev_err(data->dev, "failed to get battery inner resistance\n");
> +		return ret;
> +	}
> +
> +	/* Get battery ocv-capacity table */
> +	list = of_get_property(np, "sprd,ocv-cap-table", &size);
> +	if (!list || !size) {
> +		dev_err(data->dev, "failed to get ocv-capacity table\n");
> +		return -EINVAL;
> +	}
> +
> +	len = size / 8;
> +	data->table_len = len;
> +	data->cap_table = devm_kzalloc(data->dev,
> +				sizeof(struct sc27xx_fgu_capacity_table) * len,
> +				GFP_KERNEL);
> +	if (!data->cap_table)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < len; i++) {
> +		data->cap_table[i].ocv = be32_to_cpu(*list++);
> +		data->cap_table[i].capacity = be32_to_cpu(*list++);
> +	}
> +
> +	return 0;
> +}
> +
> +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;
> +	}
> +
> +	mutex_init(&data->lock);
> +	data->dev = &pdev->dev;
> +	data->bat_present = true;
> +
> +	ret = sc27xx_fgu_parse_dt(data, np);
> +	if (ret)
> +		return ret;
> +
> +	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
> 

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Re: [PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

[Baolin Wang]

Hi Sebastian,

On 16 September 2018 at 21:57, Sebastian Reichel
<sebastian.reichel@collabora.com> wrote:
> Hi,
>
> On Wed, Sep 12, 2018 at 03:29:38PM +0800, Baolin Wang wrote:
>> This patch adds the binding documentation for Spreadtrum SC27XX series PMICs
>> fuel gauge unit device, which is used to calculate the battery capacity.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
>> ---
>>  .../devicetree/bindings/power/supply/sc27xx-fg.txt |   55 ++++++++++++++++++++
>>  1 file changed, 55 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>>
>> diff --git a/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>> new file mode 100644
>> index 0000000..7447bae
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>> @@ -0,0 +1,55 @@
>> +Spreadtrum SC27XX PMICs Fuel Gauge Unit Power Supply Bindings
>> +
>> +Required properties:
>> +- compatible: Should be one of the following:
>> +  "sprd,sc2720-fgu",
>> +  "sprd,sc2721-fgu",
>> +  "sprd,sc2723-fgu",
>> +  "sprd,sc2730-fgu",
>> +  "sprd,sc2731-fgu".
>> +- reg: The address offset of fuel gauge unit.
>> +- bat-detect-gpio: GPIO for battery detection.
>> +- io-channels: Specify the IIO ADC channel to get temperature.
>> +- io-channel-names: Should be "bat-temp".
>> +- sprd,inner-resist: Specify the the battery inner resistance (mOhm).
>
> This should be a property of the battery.without the sprd, prefix.

Right. But I did not find one proper property of the battery, so I
will add one new standard property of battery named
'inner-resistance-microohm' in next version. Is it OK for you?

>
>> +- sprd,ocv-cap-table: Provide the battery capacity percent with corresponding
>> +  open circuit voltage (ocv) of the battery, which is used to look up current
>> +  battery capacity according to current baterry ocv values.
>
> This should also be part of the battery binding. I just reviewed a
> patchset for the Qualcomm Battery Monitoring System, which needs the
> same functionality. The Qualcomm binding is more advanced, but
> should also support this simpler case. Thus I think it makes sense
> to use its description as base for adding support for this feature
> to Documentation/devicetree/bindings/power/supply/battery.txt

That's great. But could you give me the link of Qualcomm binding,
which I can change my bindings. Thanks for your comments.

-- 
Baolin Wang
Best Regards

Re: [PATCH 2/2] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver

[Baolin Wang]

Hi Sebastian,

On 16 September 2018 at 22:35, Sebastian Reichel
<sebastian.reichel@collabora.com> wrote:
> Hi,
>
> Looks mostly good. I have a couple of comments in addition to the
> ones from the binding about using battery_info for the OCV ->
> capacity mapping.

OK.

>> +
>> +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;
>> +
>> +     *val = vol - (cur * data->inner_resist) / 1000;
>
> You multiply this with 1000 directly after this function to get back
> to uV. Just drop the division and the multiplication.

But the vol's unit is mV, so I can change to:

 *val = vol * 1000 - cur * data->inner_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 * 1000;
>> +             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);
>> +     }
>> +
>> +     if (state)
>> +             data->bat_present = true;
>> +     else
>> +             data->bat_present = false;
>> +
>> +     mutex_unlock(&data->lock);
>
> You want to call power_supply_changed() here.

Ah, right. Missed this.

>
>> +     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 = { };
>> +     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;
>> +
>> +     /* 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_parse_dt(struct sc27xx_fgu_data *data,
>> +                            struct device_node *np)
>> +{
>> +     const __be32 *list;
>> +     int i, len, size, ret;
>> +
>> +     ret = of_property_read_u32(np, "reg", &data->base);
>> +     if (ret) {
>> +             dev_err(data->dev, "failed to get fgu address\n");
>> +             return ret;
>> +     }
>> +
>> +     data->gpiod = devm_gpiod_get_optional(data->dev, "bat-detect", GPIOD_IN);
>> +     if (IS_ERR(data->gpiod)) {
>> +             dev_err(data->dev, "failed to get battery detection GPIO\n");
>> +             return PTR_ERR(data->gpiod);
>> +     }
>
> According to the binding (and the remaining code!) this gpio is not
> optional.

Yes, they are not optional. If we can not get the detection GPIO, we
will return errors. So am I missing something else?

Thanks for your comments.

>
> -- Sebastian
>
>> +     data->channel = devm_iio_channel_get(data->dev, "bat-temp");
>> +     if (IS_ERR(data->channel)) {
>> +             dev_err(data->dev, "failed to get IIO channel\n");
>> +             return PTR_ERR(data->channel);
>> +     }
>> +
>> +     /* Get the battery inner resistance */
>> +     ret = of_property_read_u32(np, "sprd,inner-resist", &data->inner_resist);
>> +     if (ret) {
>> +             dev_err(data->dev, "failed to get battery inner resistance\n");
>> +             return ret;
>> +     }
>> +
>> +     /* Get battery ocv-capacity table */
>> +     list = of_get_property(np, "sprd,ocv-cap-table", &size);
>> +     if (!list || !size) {
>> +             dev_err(data->dev, "failed to get ocv-capacity table\n");
>> +             return -EINVAL;
>> +     }
>> +
>> +     len = size / 8;
>> +     data->table_len = len;
>> +     data->cap_table = devm_kzalloc(data->dev,
>> +                             sizeof(struct sc27xx_fgu_capacity_table) * len,
>> +                             GFP_KERNEL);
>> +     if (!data->cap_table)
>> +             return -ENOMEM;
>> +
>> +     for (i = 0; i < len; i++) {
>> +             data->cap_table[i].ocv = be32_to_cpu(*list++);
>> +             data->cap_table[i].capacity = be32_to_cpu(*list++);
>> +     }
>> +
>> +     return 0;
>> +}
>> +
>> +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;
>> +     }
>> +
>> +     mutex_init(&data->lock);
>> +     data->dev = &pdev->dev;
>> +     data->bat_present = true;
>> +
>> +     ret = sc27xx_fgu_parse_dt(data, np);
>> +     if (ret)
>> +             return ret;
>> +
>> +     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
>>



-- 
Baolin Wang
Best Regards

Re: [PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

[Baolin Wang]

Hi Rob,

On 17 September 2018 at 11:26, Rob Herring <robh@kernel.org> wrote:
> On Wed, Sep 12, 2018 at 03:29:38PM +0800, Baolin Wang wrote:
>> This patch adds the binding documentation for Spreadtrum SC27XX series PMICs
>> fuel gauge unit device, which is used to calculate the battery capacity.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
>> ---
>>  .../devicetree/bindings/power/supply/sc27xx-fg.txt |   55 ++++++++++++++++++++
>>  1 file changed, 55 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>>
>> diff --git a/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>> new file mode 100644
>> index 0000000..7447bae
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>> @@ -0,0 +1,55 @@
>> +Spreadtrum SC27XX PMICs Fuel Gauge Unit Power Supply Bindings
>> +
>> +Required properties:
>> +- compatible: Should be one of the following:
>> +  "sprd,sc2720-fgu",
>> +  "sprd,sc2721-fgu",
>> +  "sprd,sc2723-fgu",
>> +  "sprd,sc2730-fgu",
>> +  "sprd,sc2731-fgu".
>> +- reg: The address offset of fuel gauge unit.
>> +- bat-detect-gpio: GPIO for battery detection.
>
> We already have sbs,battery-detect-gpios, let's drop the 'sbs,' and copy
> that.

Sure.

>
>> +- io-channels: Specify the IIO ADC channel to get temperature.
>> +- io-channel-names: Should be "bat-temp".
>> +- sprd,inner-resist: Specify the the battery inner resistance (mOhm).
>
> If this is a property of the battery, then why a sprd vendor prefix?
> This should perhaps be a common property.
>
> Minimally, it needs a unit suffix as defined in property-units.txt.

Right. As Sebastian pointed out previously we should add one common
property to describe the battery  inner resistance.

>
>> +- sprd,ocv-cap-table: Provide the battery capacity percent with corresponding
>> +  open circuit voltage (ocv) of the battery, which is used to look up current
>> +  battery capacity according to current baterry ocv values.
>
> Sounds like another battery property.

Yes.

>
>> +- monitored-battery: Phandle of battery characteristics devicetree node.
>
> If the battery is represented in another node, why are properties of the
> battery in this node.

Sure. I can remove these properties which are belonging to the battery
node. Thanks.

>
>> +  The fuel gauge uses the following battery properties:
>> +- charge-full-design-microamp-hours: battery design capacity.
>> +- constant-charge-voltage-max-microvolt: maximum constant input voltage.
>> +  See Documentation/devicetree/bindings/power/supply/battery.txt
>> +
>> +Example:
>> +
>> +     bat: battery {
>> +             compatible = "simple-battery";
>> +             charge-full-design-microamp-hours = <1900000>;
>> +             constant-charge-voltage-max-microvolt = <4350000>;
>> +             ......
>> +     };
>> +
>> +     sc2731_pmic: pmic@0 {
>> +             compatible = "sprd,sc2731";
>> +             reg = <0>;
>> +             spi-max-frequency = <26000000>;
>> +             interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
>> +             interrupt-controller;
>> +             #interrupt-cells = <2>;
>> +             #address-cells = <1>;
>> +             #size-cells = <0>;
>> +
>> +             fgu@a00 {
>> +                     compatible = "sprd,sc2731-fgu";
>> +                     reg = <0xa00>;
>> +                     bat-detect-gpio = <&pmic_eic 9 GPIO_ACTIVE_HIGH>;
>> +                     io-channels = <&pmic_adc 5>;
>> +                     io-channel-names = "bat-temp";
>> +                     sprd,inner-resist = <250>;
>> +                     sprd,ocv-cap-table = <4185 100>, <4113 95>, <4066 90>, <4022 85>, <3983 80>, <3949 75>, <3917 70>,
>> +                             <3889 65>, <3864 60>, <3835 55>, <3805 50>, <3787 45>, <3777 40>, <3773 35>, <3770 30>,
>> +                             <3765 25>, <3752 20>, <3724 15>, <3680 10>, <3605 5>, <3400 0>;
>> +                     monitored-battery = <&bat>;
>> +             };
>> +     };
>> --
>> 1.7.9.5
>>
>



-- 
Baolin Wang
Best Regards

Re: [PATCH 2/2] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 1226 bytes --]

Hi,

On Mon, Sep 17, 2018 at 12:01:51PM +0800, Baolin Wang wrote:
[...]
> >> +static int sc27xx_fgu_parse_dt(struct sc27xx_fgu_data *data,
> >> +                            struct device_node *np)
> >> +{
> >> +     const __be32 *list;
> >> +     int i, len, size, ret;
> >> +
> >> +     ret = of_property_read_u32(np, "reg", &data->base);
> >> +     if (ret) {
> >> +             dev_err(data->dev, "failed to get fgu address\n");
> >> +             return ret;
> >> +     }
> >> +
> >> +     data->gpiod = devm_gpiod_get_optional(data->dev, "bat-detect", GPIOD_IN);
> >> +     if (IS_ERR(data->gpiod)) {
> >> +             dev_err(data->dev, "failed to get battery detection GPIO\n");
> >> +             return PTR_ERR(data->gpiod);
> >> +     }
> >
> > According to the binding (and the remaining code!) this gpio is not
> > optional.
> 
> Yes, they are not optional. If we can not get the detection GPIO, we
> will return errors. So am I missing something else?
> 
> Thanks for your comments.

devm_gpiod_get_optional => devm_gpiod_get

The _optional variant will return NULL if the GPIO is not specified in DT.
The variant without _optional will return an error instead.

-- Sebastian

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH 2/2] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver

[Baolin Wang]

Hi,

On 20 September 2018 at 08:36, Sebastian Reichel
<sebastian.reichel@collabora.com> wrote:
> Hi,
>
> On Mon, Sep 17, 2018 at 12:01:51PM +0800, Baolin Wang wrote:
> [...]
>> >> +static int sc27xx_fgu_parse_dt(struct sc27xx_fgu_data *data,
>> >> +                            struct device_node *np)
>> >> +{
>> >> +     const __be32 *list;
>> >> +     int i, len, size, ret;
>> >> +
>> >> +     ret = of_property_read_u32(np, "reg", &data->base);
>> >> +     if (ret) {
>> >> +             dev_err(data->dev, "failed to get fgu address\n");
>> >> +             return ret;
>> >> +     }
>> >> +
>> >> +     data->gpiod = devm_gpiod_get_optional(data->dev, "bat-detect", GPIOD_IN);
>> >> +     if (IS_ERR(data->gpiod)) {
>> >> +             dev_err(data->dev, "failed to get battery detection GPIO\n");
>> >> +             return PTR_ERR(data->gpiod);
>> >> +     }
>> >
>> > According to the binding (and the remaining code!) this gpio is not
>> > optional.
>>
>> Yes, they are not optional. If we can not get the detection GPIO, we
>> will return errors. So am I missing something else?
>>
>> Thanks for your comments.
>
> devm_gpiod_get_optional => devm_gpiod_get
>
> The _optional variant will return NULL if the GPIO is not specified in DT.
> The variant without _optional will return an error instead.

Ah, you are definitely correct. I missed _optional and thanks for
pointing this out.

-- 
Baolin Wang
Best Regards

Re: [PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 3074 bytes --]

Hi,

On Mon, Sep 17, 2018 at 11:43:30AM +0800, Baolin Wang wrote:
> Hi Sebastian,
> 
> On 16 September 2018 at 21:57, Sebastian Reichel
> <sebastian.reichel@collabora.com> wrote:
> > Hi,
> >
> > On Wed, Sep 12, 2018 at 03:29:38PM +0800, Baolin Wang wrote:
> >> This patch adds the binding documentation for Spreadtrum SC27XX series PMICs
> >> fuel gauge unit device, which is used to calculate the battery capacity.
> >>
> >> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> >> ---
> >>  .../devicetree/bindings/power/supply/sc27xx-fg.txt |   55 ++++++++++++++++++++
> >>  1 file changed, 55 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> >> new file mode 100644
> >> index 0000000..7447bae
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> >> @@ -0,0 +1,55 @@
> >> +Spreadtrum SC27XX PMICs Fuel Gauge Unit Power Supply Bindings
> >> +
> >> +Required properties:
> >> +- compatible: Should be one of the following:
> >> +  "sprd,sc2720-fgu",
> >> +  "sprd,sc2721-fgu",
> >> +  "sprd,sc2723-fgu",
> >> +  "sprd,sc2730-fgu",
> >> +  "sprd,sc2731-fgu".
> >> +- reg: The address offset of fuel gauge unit.
> >> +- bat-detect-gpio: GPIO for battery detection.
> >> +- io-channels: Specify the IIO ADC channel to get temperature.
> >> +- io-channel-names: Should be "bat-temp".
> >> +- sprd,inner-resist: Specify the the battery inner resistance (mOhm).
> >
> > This should be a property of the battery.without the sprd, prefix.
> 
> Right. But I did not find one proper property of the battery, so I
> will add one new standard property of battery

Thanks.

> named 'inner-resistance-microohm' in next version. Is it OK for you?

The proper suffix is -micro-ohms according to
Documentation/devicetree/bindings/property-units.txt

Also the proper English term is internal resistance as far
as I know (and Wikipedia also names it this way), so I
suggest to name the property 'internal-resistance-micro-ohms'.

> >> +- sprd,ocv-cap-table: Provide the battery capacity percent with corresponding
> >> +  open circuit voltage (ocv) of the battery, which is used to look up current
> >> +  battery capacity according to current baterry ocv values.
> >
> > This should also be part of the battery binding. I just reviewed a
> > patchset for the Qualcomm Battery Monitoring System, which needs the
> > same functionality. The Qualcomm binding is more advanced, but
> > should also support this simpler case. Thus I think it makes sense
> > to use its description as base for adding support for this feature
> > to Documentation/devicetree/bindings/power/supply/battery.txt
> 
> That's great. But could you give me the link of Qualcomm binding,
> which I can change my bindings. Thanks for your comments.

https://patchwork.kernel.org/patch/10464633/

-- Sebastian

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Re: [PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

[Baolin Wang]

Hi Sebastian,

On 20 September 2018 at 08:46, Sebastian Reichel
<sebastian.reichel@collabora.com> wrote:
> Hi,
>
> On Mon, Sep 17, 2018 at 11:43:30AM +0800, Baolin Wang wrote:
>> Hi Sebastian,
>>
>> On 16 September 2018 at 21:57, Sebastian Reichel
>> <sebastian.reichel@collabora.com> wrote:
>> > Hi,
>> >
>> > On Wed, Sep 12, 2018 at 03:29:38PM +0800, Baolin Wang wrote:
>> >> This patch adds the binding documentation for Spreadtrum SC27XX series PMICs
>> >> fuel gauge unit device, which is used to calculate the battery capacity.
>> >>
>> >> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
>> >> ---
>> >>  .../devicetree/bindings/power/supply/sc27xx-fg.txt |   55 ++++++++++++++++++++
>> >>  1 file changed, 55 insertions(+)
>> >>  create mode 100644 Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>> >>
>> >> diff --git a/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>> >> new file mode 100644
>> >> index 0000000..7447bae
>> >> --- /dev/null
>> >> +++ b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
>> >> @@ -0,0 +1,55 @@
>> >> +Spreadtrum SC27XX PMICs Fuel Gauge Unit Power Supply Bindings
>> >> +
>> >> +Required properties:
>> >> +- compatible: Should be one of the following:
>> >> +  "sprd,sc2720-fgu",
>> >> +  "sprd,sc2721-fgu",
>> >> +  "sprd,sc2723-fgu",
>> >> +  "sprd,sc2730-fgu",
>> >> +  "sprd,sc2731-fgu".
>> >> +- reg: The address offset of fuel gauge unit.
>> >> +- bat-detect-gpio: GPIO for battery detection.
>> >> +- io-channels: Specify the IIO ADC channel to get temperature.
>> >> +- io-channel-names: Should be "bat-temp".
>> >> +- sprd,inner-resist: Specify the the battery inner resistance (mOhm).
>> >
>> > This should be a property of the battery.without the sprd, prefix.
>>
>> Right. But I did not find one proper property of the battery, so I
>> will add one new standard property of battery
>
> Thanks.
>
>> named 'inner-resistance-microohm' in next version. Is it OK for you?
>
> The proper suffix is -micro-ohms according to
> Documentation/devicetree/bindings/property-units.txt
>
> Also the proper English term is internal resistance as far
> as I know (and Wikipedia also names it this way), so I
> suggest to name the property 'internal-resistance-micro-ohms'.

Sure.

>
>> >> +- sprd,ocv-cap-table: Provide the battery capacity percent with corresponding
>> >> +  open circuit voltage (ocv) of the battery, which is used to look up current
>> >> +  battery capacity according to current baterry ocv values.
>> >
>> > This should also be part of the battery binding. I just reviewed a
>> > patchset for the Qualcomm Battery Monitoring System, which needs the
>> > same functionality. The Qualcomm binding is more advanced, but
>> > should also support this simpler case. Thus I think it makes sense
>> > to use its description as base for adding support for this feature
>> > to Documentation/devicetree/bindings/power/supply/battery.txt
>>
>> That's great. But could you give me the link of Qualcomm binding,
>> which I can change my bindings. Thanks for your comments.
>
> https://patchwork.kernel.org/patch/10464633/

Thanks.

-- 
Baolin Wang
Best Regards