[PATCH] power: supply: max17047: Add Maxim MAX17047 Fuel Gauge battery driver

[Hans de Goede <hdegoede@redhat.com>]

This commit adds support for the Maxim MAX17047 Fuel Gauge chip.

This was tested on a GPDwin x86 Cherry Trail machine which uses the
Maxim MAX17047 Fuel Gauge in combination with a TI bq24292i charger.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/power/supply/Kconfig            |   7 +
 drivers/power/supply/Makefile           |   1 +
 drivers/power/supply/max17047_battery.c | 286 ++++++++++++++++++++++++++++++++
 3 files changed, 294 insertions(+)
 create mode 100644 drivers/power/supply/max17047_battery.c

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index fd93110..2857513 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -538,4 +538,11 @@ config AXP20X_POWER
 	  This driver provides support for the power supply features of
 	  AXP20x PMIC.
 
+config BATTERY_MAX17047
+	tristate "Maxim MAX17047 fuel gauge driver"
+	depends on I2C
+	help
+	  Say Y here to enable support for battery monitoring with
+	  Maxim MAX17047 fuel gauge chips.
+
 endif # POWER_SUPPLY
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 3789a2c..bc72775 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -74,3 +74,4 @@ obj-$(CONFIG_CHARGER_TPS65090)	+= tps65090-charger.o
 obj-$(CONFIG_CHARGER_TPS65217)	+= tps65217_charger.o
 obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
 obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
+obj-$(CONFIG_BATTERY_MAX17047)	+= max17047_battery.o
diff --git a/drivers/power/supply/max17047_battery.c b/drivers/power/supply/max17047_battery.c
new file mode 100644
index 0000000..dc7304c
--- /dev/null
+++ b/drivers/power/supply/max17047_battery.c
@@ -0,0 +1,286 @@
+/*
+ * Maxim MAX17047 fuel gauge driver
+ * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/power_supply.h>
+#include <linux/slab.h>
+
+#define MAX17047_STATUS					0x00
+#define MAX17047_STATUS_BAT_NOT_PRESENT			BIT(3)
+#define MAX17047_REM_CAP_REP				0x05
+#define MAX17047_SOC_REP				0x06
+#define MAX17047_VCELL					0x09
+#define MAX17047_CURRENT				0x0a
+#define MAX17047_AVG_CURRENT				0x0b
+#define MAX17047_FULL_CAP				0x10
+#define MAX17047_FULL_SOC_THR				0x13
+#define MAX17047_DESIGN_CAP				0x18
+#define MAX17047_AVG_VCELL				0x19
+#define MAX17047_MAXMIN_VCELL				0x1b
+#define MAX17047_VFOCV					0xfb
+
+/* A-scales are based on the reference design Rsense = 0.010Ω. */
+#define UAH_SCALE					500, false
+#define UA_SCALE					156, true
+#define UV_SCALE					(625 / 8), false
+
+/* Consider REM_CAP_REP which is less then 10 units below FULL_CAP full */
+#define FULL_THRESHOLD					10
+
+struct max17047_fg_data {
+	struct i2c_client *client;
+	struct power_supply *battery;
+};
+
+static int max17047_get(struct max17047_fg_data *fg, u8 reg,
+			union power_supply_propval *val,
+			int scale, bool sign_extend)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(fg->client, reg);
+	if (ret < 0)
+		return ret;
+
+	if (sign_extend)
+		ret = sign_extend32(ret, 15);
+
+	val->intval = ret * scale;
+
+	return 0;
+}
+
+static int max17047_get_status(struct max17047_fg_data *fg,
+			       union power_supply_propval *val)
+{
+	int charge_full, charge_now;
+
+	if (!power_supply_am_i_supplied(fg->battery)) {
+		val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
+		return 0;
+	}
+
+	/*
+	 * The MAX17047 has builtin end-of-charge detection and will update
+	 * FULL_CAP to match REM_CAP_REP when it detects end of charging.
+	 *
+	 * When this cycle the battery gets charged to a higher (calculated)
+	 * capacity then the previous cycle then FULL_CAP will get updated
+	 * contineously once end-of-charge detection kicks in, so allow the
+	 * 2 to differ a bit.
+	 */
+
+	charge_full = i2c_smbus_read_word_data(fg->client, MAX17047_FULL_CAP);
+	if (charge_full < 0)
+		return charge_full;
+
+	charge_now = i2c_smbus_read_word_data(fg->client, MAX17047_REM_CAP_REP);
+	if (charge_now < 0)
+		return charge_now;
+
+	if ((charge_full - charge_now) <= FULL_THRESHOLD)
+		val->intval = POWER_SUPPLY_STATUS_FULL;
+	else
+		val->intval = POWER_SUPPLY_STATUS_CHARGING;
+
+	return 0;
+}
+
+static int max17047_get_present(struct max17047_fg_data *fg,
+				union power_supply_propval *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(fg->client, MAX17047_STATUS);
+	if (ret < 0)
+		return ret;
+
+	if (ret & MAX17047_STATUS_BAT_NOT_PRESENT)
+		val->intval = 0;
+	else
+		val->intval = 1;
+
+	return 0;
+}
+
+static int max17047_get_min_max_volt(struct max17047_fg_data *fg,
+				     union power_supply_propval *min_val,
+				     union power_supply_propval *max_val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(fg->client, MAX17047_MAXMIN_VCELL);
+	if (ret < 0)
+		return ret;
+
+	if (min_val)
+		/* Lower byte contains min in 20mV units */
+		min_val->intval = (ret & 0xff) * 20000;
+
+	if (max_val)
+		/* Upper byte contains max in 20mV units */
+		max_val->intval = (ret >> 8) * 20000;
+
+	return 0;
+}
+
+static int max17047_get_property(struct power_supply *psy,
+	enum power_supply_property prop, union power_supply_propval *val)
+{
+	struct max17047_fg_data *fg = power_supply_get_drvdata(psy);
+	int ret = 0;
+
+	switch (prop) {
+	case POWER_SUPPLY_PROP_STATUS:
+		ret = max17047_get_status(fg, val);
+		break;
+	case POWER_SUPPLY_PROP_PRESENT:
+		ret = max17047_get_present(fg, val);
+		break;
+	case POWER_SUPPLY_PROP_TECHNOLOGY:
+		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MAX:
+		max17047_get_min_max_volt(fg, NULL, val);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MIN:
+		max17047_get_min_max_volt(fg, val, NULL);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = max17047_get(fg, MAX17047_VCELL, val, UV_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
+		ret = max17047_get(fg, MAX17047_AVG_VCELL, val, UV_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+		ret = max17047_get(fg, MAX17047_VFOCV, val, UV_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		ret = max17047_get(fg, MAX17047_CURRENT, val, UA_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		ret = max17047_get(fg, MAX17047_AVG_CURRENT, val, UA_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		ret = max17047_get(fg, MAX17047_DESIGN_CAP, val, UAH_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL:
+		ret = max17047_get(fg, MAX17047_FULL_CAP, val, UAH_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		ret = max17047_get(fg, MAX17047_REM_CAP_REP, val, UAH_SCALE);
+		break;
+	case POWER_SUPPLY_PROP_CAPACITY:
+		ret = i2c_smbus_read_word_data(fg->client, MAX17047_SOC_REP);
+		if (ret >= 0)
+			val->intval = ret >> 8; /* Reg is in fixed 8.8 fmt */
+		break;
+	case POWER_SUPPLY_PROP_SCOPE:
+		val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
+		break;
+	default:
+		ret = -ENODATA;
+	}
+
+	return ret;
+}
+
+static void max17047_external_power_changed(struct power_supply *psy)
+{
+	power_supply_changed(psy);
+}
+
+static enum power_supply_property max17047_properties[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_VOLTAGE_MAX,
+	POWER_SUPPLY_PROP_VOLTAGE_MIN,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_VOLTAGE_AVG,
+	POWER_SUPPLY_PROP_VOLTAGE_OCV,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CURRENT_AVG,
+	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+	POWER_SUPPLY_PROP_CHARGE_FULL,
+	POWER_SUPPLY_PROP_CHARGE_NOW,
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_SCOPE,
+};
+
+static const struct power_supply_desc bat_desc = {
+	/* .name must match chargers supplied_to setting, do not change */
+	.name			= "main-battery",
+	.type			= POWER_SUPPLY_TYPE_BATTERY,
+	.properties		= max17047_properties,
+	.num_properties		= ARRAY_SIZE(max17047_properties),
+	.get_property		= max17047_get_property,
+	.external_power_changed = max17047_external_power_changed,
+};
+
+static int max17047_probe(struct i2c_client *client,
+			const struct i2c_device_id *i2c_id)
+{
+	struct device *dev = &client->dev;
+	struct power_supply_config bat_cfg = {};
+	struct max17047_fg_data *fg;
+	int ret;
+
+	fg = devm_kzalloc(dev, sizeof(*fg), GFP_KERNEL);
+	if (!fg)
+		return -ENOMEM;
+
+	fg->client = client;
+
+	/*
+	 * Enable End-of-Charge Detection when the voltage FG reports 95%
+	 * or more, as recommend in the datasheet.
+	 */
+	ret = i2c_smbus_write_word_data(fg->client, MAX17047_FULL_SOC_THR,
+					95 << 8);
+	if (ret < 0) {
+		dev_err(dev, "Error setting FULL_SOC_THR: %d\n", ret);
+		return ret;
+	}
+
+	bat_cfg.drv_data = fg;
+	fg->battery = devm_power_supply_register(dev, &bat_desc, &bat_cfg);
+	if (IS_ERR(fg->battery))
+		return PTR_ERR(fg->battery);
+
+	return 0;
+}
+
+static const struct i2c_device_id max17047_i2c_id[] = {
+	{ "max17047", },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max17047_i2c_id);
+
+static struct i2c_driver max17047_driver = {
+	.driver	= {
+		.name	= "CHT Whiskey Cove PMIC Fuel Gauge",
+	},
+	.probe = max17047_probe,
+	.id_table = max17047_i2c_id,
+};
+
+module_i2c_driver(max17047_driver);
+
+MODULE_DESCRIPTION("Maxim MAX17047 fuel gauge driver");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_LICENSE("GPL");
-- 
2.9.3