[PATCH v2 2/2] power: supply: add LT8491 battery charger driver

[John Erasmus Mari Geronimo <johnerasmusmari.geronimo@analog.com>]

Adds initial support for the LT8491 High Voltage Buck-Boost Battery
Charge Controller with I2C

The driver provides functionality to monitor key parameters including:
Voltage, Current, Power, Temperature, Status

Signed-off-by: John Erasmus Mari Geronimo <johnerasmusmari.geronimo@analog.com>
---
 MAINTAINERS                           |   1 +
 drivers/power/supply/Kconfig          |   9 +
 drivers/power/supply/Makefile         |   1 +
 drivers/power/supply/lt8491_charger.c | 412 ++++++++++++++++++++++++++
 4 files changed, 423 insertions(+)
 create mode 100644 drivers/power/supply/lt8491_charger.c

diff --git a/MAINTAINERS b/MAINTAINERS
index d79187312f789..317ca2e8ca9bd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15175,6 +15175,7 @@ M:	John Erasmus Mari Geronimo <johnerasmusmari.geronimo@analog.com>
 L:	linux-pm@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/power/supply/adi,lt8491.yaml
+F:	drivers/power/supply/lt8491_charger.c
 
 LTC1660 DAC DRIVER
 M:	Marcus Folkesson <marcus.folkesson@gmail.com>
diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index f0ede1cecb6a8..146ea3743eb2d 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -598,6 +598,15 @@ config CHARGER_LT3651
 	  Say Y to include support for the Analog Devices (Linear Technology)
 	  LT3651 battery charger which reports its status via GPIO lines.
 
+config CHARGER_LT8491
+	tristate "Analog Devices LT8491 charger"
+	depends on I2C
+	help
+	  Say Y to include support for the Analog Devices (Linear Technology)
+	  LT8491 battery charge controller connected to I2C. The LT8491 is a
+	  high voltage buck-boost switching regulator battery charger
+	  controller.
+
 config CHARGER_LTC4162L
 	tristate "LTC4162-L charger"
 	depends on I2C
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 31fe4a145929a..d3d2721333204 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -81,6 +81,7 @@ obj-$(CONFIG_CHARGER_LP8788)	+= lp8788-charger.o
 obj-$(CONFIG_CHARGER_GPIO)	+= gpio-charger.o
 obj-$(CONFIG_CHARGER_MANAGER)	+= charger-manager.o
 obj-$(CONFIG_CHARGER_LT3651)	+= lt3651-charger.o
+obj-$(CONFIG_CHARGER_LT8491)	+= lt8491_charger.o
 obj-$(CONFIG_CHARGER_LTC4162L)	+= ltc4162-l-charger.o
 obj-$(CONFIG_CHARGER_MAX14577)	+= max14577_charger.o
 obj-$(CONFIG_CHARGER_DETECTOR_MAX14656)	+= max14656_charger_detector.o
diff --git a/drivers/power/supply/lt8491_charger.c b/drivers/power/supply/lt8491_charger.c
new file mode 100644
index 0000000000000..225d5dd4dd721
--- /dev/null
+++ b/drivers/power/supply/lt8491_charger.c
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices LT8491 Battery Charger
+ *
+ * Copyright 2024 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/power_supply.h>
+
+#define LT8491_TELE_TBAT_REG 0x0
+#define LT8491_TELE_POUT_REG 0x2
+#define LT8491_TELE_PIN_REG  0x4
+#define LT8491_TELE_EFF_REG  0x6
+#define LT8491_TELE_IOUT_REG 0x8
+#define LT8491_TELE_IIN_REG  0xA
+#define LT8491_TELE_VBAT_REG 0xC
+#define LT8491_TELE_VIN_REG  0xE
+#define LT8491_TELE_VINR_REG 0x10
+#define LT8491_STAT_CHARGER_REG 0x12
+#define LT8491_STAT_CHRG_FAULTS_REG 0x19
+#define LT8491_CTRL_UPDATE_TELEM_REG 0x26
+
+#define LT8491_CFG_RSENSE1_REG 0x28
+#define LT8491_CFG_RIMON_OUT_REG 0x2A
+#define LT8491_CFG_RSENSE2_REG 0x2C
+#define LT8491_CFG_RDACO_REG 0x2E
+#define LT8491_CFG_RFBOUT1_REG 0x30
+#define LT8491_CFG_RFBOUT2_REG 0x32
+#define LT8491_CFG_RDACI_REG 0x34
+#define LT8491_CFG_RFBIN2_REG 0x36
+#define LT8491_CFG_RFBIN1_REG 0x38
+#define LT8491_CFG_TBAT_MIN_REG 0x40
+#define LT8491_CFG_TBAT_MAX_REG 0x41
+#define LT8491_MFR_DATA1_LSB_REG 0x5C
+
+#define LT8491_TELEM_ACTIVE_MASK BIT(6)
+#define LT8491_CHARGING_MASK BIT(2)
+#define LT8491_BAT_DISCON_FLT_MASK BIT(3)
+
+#define LT8491_UPDATE_TELEM_CMD 0xAA
+
+#define LT8491_MFR_DATA_LEN 0x3
+
+struct lt8491_info {
+	struct i2c_client *client;
+	struct power_supply *psp;
+	char serial_number[16];
+	/* protect against device accesses */
+	struct mutex lock;
+};
+
+static int lt8491_read_serial_number(struct lt8491_info *info)
+{
+	int i, ret;
+	int serial_number[LT8491_MFR_DATA_LEN];
+
+	for (i = 0; i < LT8491_MFR_DATA_LEN; i++) {
+		serial_number[i] = i2c_smbus_read_word_data(info->client,
+					LT8491_MFR_DATA1_LSB_REG + i * 2);
+		if (serial_number[i] < 0)
+			return serial_number[i];
+	}
+
+	ret = sprintf(info->serial_number, "%04x%04x%04x", serial_number[0],
+		      serial_number[1], serial_number[2]);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int lt8491_get_property(struct power_supply *psy,
+				enum power_supply_property psp,
+				union power_supply_propval *val)
+{
+	struct lt8491_info *info = power_supply_get_drvdata(psy);
+	s16 ret;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		ret = i2c_smbus_read_byte_data(info->client,
+					       LT8491_STAT_CHARGER_REG);
+		if (ret < 0)
+			return ret;
+
+		val->intval = FIELD_GET(LT8491_CHARGING_MASK, ret) ?
+					POWER_SUPPLY_STATUS_CHARGING :
+					POWER_SUPPLY_STATUS_NOT_CHARGING;
+
+		return 0;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		scoped_guard(mutex, &info->lock) {
+			ret = i2c_smbus_read_byte_data(info->client,
+						LT8491_STAT_CHARGER_REG);
+			if (ret < 0)
+				return ret;
+
+			if (!FIELD_GET(LT8491_TELEM_ACTIVE_MASK, ret)) {
+				ret = i2c_smbus_write_byte_data(info->client,
+						LT8491_CTRL_UPDATE_TELEM_REG,
+						LT8491_UPDATE_TELEM_CMD);
+				if (ret)
+					return ret;
+			}
+
+			ret = i2c_smbus_read_word_data(info->client,
+						LT8491_TELE_VBAT_REG);
+			if (ret < 0)
+				return ret;
+		}
+
+		val->intval = ret * 10000;
+
+		return 0;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		scoped_guard(mutex, &info->lock) {
+			ret = i2c_smbus_read_byte_data(info->client,
+						       LT8491_STAT_CHARGER_REG);
+			if (ret < 0)
+				return ret;
+
+			if (!FIELD_GET(LT8491_TELEM_ACTIVE_MASK, ret)) {
+				ret = i2c_smbus_write_byte_data(info->client,
+						LT8491_CTRL_UPDATE_TELEM_REG,
+						LT8491_UPDATE_TELEM_CMD);
+				if (ret)
+					return ret;
+			}
+
+			ret = i2c_smbus_read_word_data(info->client,
+						       LT8491_TELE_IOUT_REG);
+			if (ret < 0)
+				return ret;
+		}
+
+		val->intval = ret;
+
+		return 0;
+	case POWER_SUPPLY_PROP_POWER_NOW:
+		scoped_guard(mutex, &info->lock) {
+			ret = i2c_smbus_read_byte_data(info->client,
+						       LT8491_STAT_CHARGER_REG);
+			if (ret < 0)
+				return ret;
+
+			if (!FIELD_GET(LT8491_TELEM_ACTIVE_MASK, ret)) {
+				ret = i2c_smbus_write_byte_data(info->client,
+						LT8491_CTRL_UPDATE_TELEM_REG,
+						LT8491_UPDATE_TELEM_CMD);
+				if (ret)
+					return ret;
+			}
+
+			ret = i2c_smbus_read_word_data(info->client,
+						       LT8491_TELE_POUT_REG);
+			if (ret < 0)
+				return ret;
+		}
+
+		val->intval = ret * 10000;
+
+		return 0;
+	case POWER_SUPPLY_PROP_TEMP:
+		scoped_guard(mutex, &info->lock) {
+			ret = i2c_smbus_read_byte_data(info->client,
+						       LT8491_STAT_CHARGER_REG);
+			if (ret < 0)
+				return ret;
+
+			if (!FIELD_GET(LT8491_TELEM_ACTIVE_MASK, ret)) {
+				ret = i2c_smbus_write_byte_data(info->client,
+						LT8491_CTRL_UPDATE_TELEM_REG,
+						LT8491_UPDATE_TELEM_CMD);
+				if (ret)
+					return ret;
+			}
+
+			ret = i2c_smbus_read_word_data(info->client,
+						       LT8491_TELE_TBAT_REG);
+			if (ret < 0)
+				return ret;
+		}
+
+		val->intval = sign_extend32(ret, 15);
+
+		return 0;
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+		ret = i2c_smbus_read_byte_data(info->client,
+					       LT8491_CFG_TBAT_MIN_REG);
+		if (ret < 0)
+			return ret;
+
+		val->intval = sign_extend32(ret, 7) * 10;
+
+		return 0;
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		ret = i2c_smbus_read_byte_data(info->client,
+					       LT8491_CFG_TBAT_MAX_REG);
+		if (ret < 0)
+			return ret;
+
+		val->intval = sign_extend32(ret, 7) * 10;
+
+		return 0;
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval = "lt8491";
+
+		return 0;
+	case POWER_SUPPLY_PROP_MANUFACTURER:
+		val->strval = "Analog Devices";
+
+		return 0;
+	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
+		val->strval = info->serial_number;
+
+		return 0;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static int lt8491_set_property(struct power_supply *psy,
+				enum power_supply_property psp,
+				const union power_supply_propval *val)
+{
+	struct lt8491_info *info = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+		return i2c_smbus_write_byte_data(info->client,
+						 LT8491_CFG_TBAT_MIN_REG,
+						 val->intval / 10);
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		return i2c_smbus_write_byte_data(info->client,
+						 LT8491_CFG_TBAT_MAX_REG,
+						 val->intval / 10);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int lt8491_property_is_writeable(struct power_supply *psy,
+					enum power_supply_property psp)
+{
+	switch (psp) {
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+static enum power_supply_property lt8491_properties[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_POWER_NOW,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_TEMP_ALERT_MIN,
+	POWER_SUPPLY_PROP_TEMP_ALERT_MAX,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+	POWER_SUPPLY_PROP_MANUFACTURER,
+	POWER_SUPPLY_PROP_SERIAL_NUMBER,
+};
+
+static const struct power_supply_desc lt8491_desc = {
+	.name		= "lt8491",
+	.type		= POWER_SUPPLY_TYPE_BATTERY,
+	.properties	= lt8491_properties,
+	.num_properties	= ARRAY_SIZE(lt8491_properties),
+	.get_property	= lt8491_get_property,
+	.set_property	= lt8491_set_property,
+	.property_is_writeable = lt8491_property_is_writeable,
+};
+
+static int lt8491_configure_resistor(struct lt8491_info *info,
+				     const char *propname, int divider,
+				     unsigned int reg)
+{
+	struct device *dev = &info->client->dev;
+	int ret;
+	u32 val;
+
+	ret = device_property_read_u32(dev, propname, &val);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Missing %s property.\n",
+				     propname);
+
+	return i2c_smbus_write_word_data(info->client, reg, val / divider);
+}
+
+static int lt8491_configure_telemetry(struct lt8491_info *info)
+{
+	int ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rsense1-micro-ohms", 10,
+					LT8491_CFG_RSENSE1_REG);
+	if (ret)
+		return ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rimon-out-ohms", 10,
+					LT8491_CFG_RIMON_OUT_REG);
+	if (ret)
+		return ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rsense2-micro-ohms", 10,
+					LT8491_CFG_RSENSE2_REG);
+	if (ret)
+		return ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rdaco-ohms", 10,
+					LT8491_CFG_RDACO_REG);
+	if (ret)
+		return ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rfbout1-ohms", 100,
+					LT8491_CFG_RFBOUT1_REG);
+	if (ret)
+		return ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rfbout2-ohms", 10,
+					LT8491_CFG_RFBOUT2_REG);
+	if (ret)
+		return ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rdaci-ohms", 10,
+					LT8491_CFG_RDACI_REG);
+	if (ret)
+		return ret;
+
+	ret = lt8491_configure_resistor(info, "adi,rfbin2-ohms", 10,
+					LT8491_CFG_RFBIN2_REG);
+	if (ret)
+		return ret;
+
+	return lt8491_configure_resistor(info, "adi,rfbin1-ohms", 100,
+					 LT8491_CFG_RFBIN1_REG);
+}
+
+static int lt8491_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct lt8491_info *info;
+	struct power_supply_config psy_cfg = {};
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_READ_WORD_DATA))
+		return -EOPNOTSUPP;
+
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->client = client;
+	psy_cfg.drv_data = info;
+
+	ret = devm_mutex_init(dev, &info->lock);
+	if (ret)
+		return ret;
+
+	ret = lt8491_read_serial_number(info);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Can't read serial. Hardware error.\n");
+
+	ret = lt8491_configure_telemetry(info);
+	if (ret)
+		return ret;
+
+	info->psp = power_supply_register(dev, &lt8491_desc, &psy_cfg);
+	if (IS_ERR(info->psp))
+		return dev_err_probe(dev, PTR_ERR(info->psp),
+				     "Failed to register power supply.\n");
+
+	return 0;
+}
+
+static const struct i2c_device_id lt8491_id[] = {
+	{ "lt8491", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lt8491_id);
+
+static const struct of_device_id lt8491_of_match[] = {
+	{ .compatible = "adi,lt8491" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, lt8491_of_match);
+
+static struct i2c_driver lt8491_driver = {
+	.driver = {
+		.name = "lt8491",
+		.of_match_table = lt8491_of_match,
+	},
+	.probe = lt8491_probe,
+	.id_table = lt8491_id,
+};
+module_i2c_driver(lt8491_driver);
+
+MODULE_AUTHOR("John Erasmus Mari Geronimo <johnerasmusmari.geronimo@analog.com");
+MODULE_DESCRIPTION("LT8491 battery charger");
+MODULE_LICENSE("GPL");
-- 
2.34.1