Message-ID: <20240408064905.20298-2-mike.looijmans@topic.nl>
Date: Mon, 8 Apr 2024 08:49:05 +0200
From: Mike Looijmans <mike.looijmans@...ic.nl>
To: linux-pm@...r.kernel.org
CC: Mike Looijmans <mike.looijmans@...ic.nl>,
	Sebastian Reichel <sre@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] power: supply: ltc3350-charger: Add driver

The LTC3350 is a backup power controller that can charge and monitor
a series stack of one to four supercapacitors.

Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>

---

 drivers/power/supply/Kconfig           |  10 +
 drivers/power/supply/Makefile          |   1 +
 drivers/power/supply/ltc3350-charger.c | 720 +++++++++++++++++++++++++
 3 files changed, 731 insertions(+)
 create mode 100644 drivers/power/supply/ltc3350-charger.c

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index 3e31375491d5..7cb1a66e522d 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -514,6 +514,16 @@ 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_LTC3350
+	tristate "LTC3350 Supercapacitor Backup Controller and System Monitor"
+	depends on I2C
+	select REGMAP_I2C
+	select I2C_SMBUS
+	help
+	  Say Y to include support for the Analog Devices (Linear Technology)
+	  LTC3350 Supercapacitor Backup Controller and System Monitor connected
+	  to I2C.
+
 config CHARGER_LTC4162L
 	tristate "LTC4162-L charger"
 	depends on I2C
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 58b567278034..a8d618e4ac91 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -72,6 +72,7 @@ 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-$(CONFIG_CHARGER_LTC3350)	+= ltc3350-charger.o
 obj-$(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/ltc3350-charger.c b/drivers/power/supply/ltc3350-charger.c
new file mode 100644
index 000000000000..b3a23447ebf4
--- /dev/null
+++ b/drivers/power/supply/ltc3350-charger.c
@@ -0,0 +1,720 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for Analog Devices (Linear Technology) LTC3350
+ * High Current Supercapacitor Backup Controller and System Monitor
+ * Copyright (C) 2024, Topic Embedded Products
+ */
+
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/of_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/power_supply.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+
+/* Registers (names based on what datasheet uses) */
+#define LTC3350_REG_CLR_ALARMS		0x00
+#define LTC3350_REG_MSK_ALARMS		0x01
+#define LTC3350_REG_MSK_MON_STATUS	0x02
+#define LTC3350_REG_CAP_ESR_PER		0x04
+#define LTC3350_REG_VCAPFB_DAC		0x05
+#define LTC3350_REG_VSHUNT		0x06
+#define LTC3350_REG_CAP_UV_LVL		0x07
+#define LTC3350_REG_CAP_OV_LVL		0x08
+#define LTC3350_REG_GPI_UV_LVL		0x09
+#define LTC3350_REG_GPI_OV_LVL		0x0A
+#define LTC3350_REG_VIN_UV_LVL		0x0B
+#define LTC3350_REG_VIN_OV_LVL		0x0C
+#define LTC3350_REG_VCAP_UV_LVL		0x0D
+#define LTC3350_REG_VCAP_OV_LVL		0x0E
+#define LTC3350_REG_VOUT_UV_LVL		0x0F
+#define LTC3350_REG_VOUT_OV_LVL		0x10
+#define LTC3350_REG_IIN_OC_LVL		0x11
+#define LTC3350_REG_ICHG_UC_LVL		0x12
+#define LTC3350_REG_DTEMP_COLD_LVL	0x13
+#define LTC3350_REG_DTEMP_HOT_LVL	0x14
+#define LTC3350_REG_ESR_HI_LVL		0x15
+#define LTC3350_REG_CAP_LO_LVL		0x16
+#define LTC3350_REG_CTL_REG		0x17
+#define LTC3350_REG_NUM_CAPS		0x1A
+#define LTC3350_REG_CHRG_STATUS		0x1B
+#define LTC3350_REG_MON_STATUS		0x1C
+#define LTC3350_REG_ALARM_REG		0x1D
+#define LTC3350_REG_MEAS_CAP		0x1E
+#define LTC3350_REG_MEAS_ESR		0x1F
+#define LTC3350_REG_MEAS_VCAP1		0x20
+#define LTC3350_REG_MEAS_VCAP2		0x21
+#define LTC3350_REG_MEAS_VCAP3		0x22
+#define LTC3350_REG_MEAS_VCAP4		0x23
+#define LTC3350_REG_MEAS_GPI		0x24
+#define LTC3350_REG_MEAS_VIN		0x25
+#define LTC3350_REG_MEAS_VCAP		0x26
+#define LTC3350_REG_MEAS_VOUT		0x27
+#define LTC3350_REG_MEAS_IIN		0x28
+#define LTC3350_REG_MEAS_ICHG		0x29
+#define LTC3350_REG_MEAS_DTEMP		0x2A
+
+/* LTC3350_REG_CLR_ALARMS, LTC3350_REG_MASK_ALARMS, LTC3350_REG_ALARM_REG */
+#define LTC3350_MSK_CAP_UV	BIT(0)	/* capacitor undervoltage alarm */
+#define LTC3350_MSK_CAP_OV	BIT(1)	/* capacitor overvoltage alarm */
+#define LTC3350_MSK_GPI_UV	BIT(2)	/* GPI undervoltage alarm */
+#define LTC3350_MSK_GPI_OV	BIT(3)	/* GPI overvoltage alarm */
+#define LTC3350_MSK_VIN_UV	BIT(4)	/* VIN undervoltage alarm */
+#define LTC3350_MSK_VIN_OV	BIT(5)	/* VIN overvoltage alarm */
+#define LTC3350_MSK_VCAP_UV	BIT(6)	/* VCAP undervoltage alarm */
+#define LTC3350_MSK_VCAP_OV	BIT(7)	/* VCAP overvoltage alarm */
+#define LTC3350_MSK_VOUT_UV	BIT(8)	/* VOUT undervoltage alarm */
+#define LTC3350_MSK_VOUT_OV	BIT(9)	/* VOUT overvoltage alarm */
+#define LTC3350_MSK_IIN_OC	BIT(10)	/* input overcurrent alarm */
+#define LTC3350_MSK_ICHG_UC	BIT(11)	/* charge undercurrent alarm */
+#define LTC3350_MSK_DTEMP_COLD	BIT(12)	/* die temperature cold alarm */
+#define LTC3350_MSK_DTEMP_HOT	BIT(13)	/* die temperature hot alarm */
+#define LTC3350_MSK_ESR_HI	BIT(14)	/* ESR high alarm */
+#define LTC3350_MSK_CAP_LO	BIT(15)	/* capacitance low alarm */
+
+/* LTC3350_REG_MSK_MON_STATUS masks */
+#define LTC3350_MSK_MON_CAPESR_ACTIVE		BIT(0)
+#define LTC3350_MSK_MON_CAPESR_SCHEDULED	BIT(1)
+#define LTC3350_MSK_MON_CAPESR_PENDING		BIT(2)
+#define LTC3350_MSK_MON_CAP_DONE		BIT(3)
+#define LTC3350_MSK_MON_ESR_DONE		BIT(4)
+#define LTC3350_MSK_MON_CAP_FAILED		BIT(5)
+#define LTC3350_MSK_MON_ESR_FAILED		BIT(6)
+#define LTC3350_MSK_MON_POWER_FAILED		BIT(8)
+#define LTC3350_MSK_MON_POWER_RETURNED		BIT(9)
+
+/* LTC3350_REG_CTL_REG */
+/* Begin a capacitance and ESR measurement when possible */
+#define LTC3350_CTL_STRT_CAPESR		BIT(0)
+/* A one in this bit location enables the input buffer on the GPI pin */
+#define LTC3350_CTL_GPI_BUFFER_EN	BIT(1)
+/* Stops an active capacitance/ESR measurement */
+#define LTC3350_CTL_STOP_CAPESR		BIT(2)
+/* Increases capacitor measurement resolution by 100x for smaller capacitors */
+#define LTC3350_CTL_CAP_SCALE		BIT(3)
+
+/* LTC3350_REG_CHRG_STATUS */
+#define LTC3350_CHRG_STEPDOWN	BIT(0)	/* Synchronous controller in step-down mode (charging) */
+#define LTC3350_CHRG_STEPUP	BIT(1)	/* Synchronous controller in step-up mode (backup) */
+#define LTC3350_CHRG_CV		BIT(2)	/* The charger is in constant voltage mode */
+#define LTC3350_CHRG_UVLO	BIT(3)	/* The charger is in undervoltage lockout */
+#define LTC3350_CHRG_INPUT_ILIM	BIT(4)	/* The charger is in input current limit */
+#define LTC3350_CHRG_CAPPG	BIT(5)	/* The capacitor voltage is above power good threshold */
+#define LTC3350_CHRG_SHNT	BIT(6)	/* The capacitor manager is shunting */
+#define LTC3350_CHRG_BAL	BIT(7)	/* The capacitor manager is balancing */
+#define LTC3350_CHRG_DIS	BIT(8)	/* Charger disabled for capacitance measurement */
+#define LTC3350_CHRG_CI		BIT(9)	/* The charger is in constant current mode */
+#define LTC3350_CHRG_PFO	BIT(11)	/* Input voltage is below PFI threshold */
+
+/* LTC3350_REG_MON_STATUS */
+#define LTC3350_MON_CAPESR_ACTIVE	BIT(0)	/* Capacitance/ESR measurement in progress */
+#define LTC3350_MON_CAPESR_SCHEDULED	BIT(1)	/* Waiting programmed time */
+#define LTC3350_MON_CAPESR_PENDING	BIT(2)	/* Waiting for satisfactory conditions */
+#define LTC3350_MON_CAP_DONE		BIT(3)	/* Capacitance measurement has completed */
+#define LTC3350_MON_ESR_DONE		BIT(4)	/* ESR Measurement has completed */
+#define LTC3350_MON_CAP_FAILED		BIT(5)	/* Last capacitance measurement failed */
+#define LTC3350_MON_ESR_FAILED		BIT(6)	/* Last ESR measurement failed */
+#define LTC3350_MON_POWER_FAILED	BIT(8)	/* Unable to charge */
+#define LTC3350_MON_POWER_RETURNED	BIT(9)	/* Able to charge */
+
+
+struct ltc3350_info {
+	struct i2c_client	*client;
+	struct regmap		*regmap;
+	struct power_supply	*charger;
+	u32 rsnsc;	/* Series resistor that sets charge current, microOhm */
+	u32 rsnsi;	/* Series resistor to measure input current, microOhm */
+};
+
+/*
+ * About LTC3350 "alarm" functions: Setting a bit in the LTC3350_REG_MSK_ALARMS
+ * register enables the alarm. The alarm will trigger an SMBALERT only once.
+ * To reset the alarm, write a "1" bit to LTC3350_REG_CLR_ALARMS. Then the alarm
+ * will trigger another SMBALERT when conditions are met (may be immediately).
+ * After writing to one of the corresponding level registers, enable the alarm,
+ * so that a UEVENT triggers when the alarm goes off.
+ */
+static void ltc3350_enable_alarm(struct ltc3350_info *info, unsigned int reg)
+{
+	unsigned int mask;
+
+	/* Register locations correspond to alarm mask bits */
+	mask = BIT(reg - LTC3350_REG_CAP_UV_LVL);
+	/* Clear the alarm bit so it may trigger again */
+	regmap_write(info->regmap, LTC3350_REG_CLR_ALARMS, mask);
+	/* Enable the alarm */
+	regmap_update_bits(info->regmap, LTC3350_REG_MSK_ALARMS, mask, mask);
+}
+
+/* Convert enum value to POWER_SUPPLY_STATUS value */
+static int ltc3350_state_decode(unsigned int value)
+{
+	if (value & LTC3350_CHRG_STEPUP)
+		return POWER_SUPPLY_STATUS_DISCHARGING; /* running on backup */
+
+	if (value & LTC3350_CHRG_PFO)
+		return POWER_SUPPLY_STATUS_NOT_CHARGING;
+
+	if (value & LTC3350_CHRG_STEPDOWN) {
+		/* The chip remains in CV mode indefinitely, hence "full" */
+		if (value & LTC3350_CHRG_CV)
+			return POWER_SUPPLY_STATUS_FULL;
+
+		return POWER_SUPPLY_STATUS_CHARGING;
+	}
+
+	/* Not in step down? Must be full then (never seen this) */
+	return POWER_SUPPLY_STATUS_FULL;
+};
+
+static int ltc3350_get_status(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	val->intval = ltc3350_state_decode(regval);
+
+	return 0;
+}
+
+static int ltc3350_charge_status_decode(unsigned int value)
+{
+	if (!(value & LTC3350_CHRG_STEPDOWN))
+		return POWER_SUPPLY_CHARGE_TYPE_NONE;
+
+	/* constant voltage is "topping off" */
+	if (value & LTC3350_CHRG_CV)
+		return POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
+
+	/* input limiter */
+	if (value & LTC3350_CHRG_INPUT_ILIM)
+		return POWER_SUPPLY_CHARGE_TYPE_ADAPTIVE;
+
+	/* constant current is "fast" */
+	if (value & LTC3350_CHRG_CI)
+		return POWER_SUPPLY_CHARGE_TYPE_FAST;
+
+	return POWER_SUPPLY_CHARGE_TYPE_UNKNOWN;
+}
+
+static int ltc3350_get_charge_type(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	val->intval = ltc3350_charge_status_decode(regval);
+
+	return 0;
+}
+
+static int ltc3350_get_online(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MON_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	/* indicates if input voltage is sufficient to charge */
+	val->intval = !!(regval & LTC3350_MON_POWER_RETURNED);
+
+	return 0;
+}
+
+static int ltc3350_get_input_voltage(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_VIN, &regval);
+	if (ret)
+		return ret;
+
+	/* 2.21mV/LSB */
+	val->intval =  regval * 2210;
+
+	return 0;
+}
+
+static int ltc3350_get_input_current(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_IIN, &regval);
+	if (ret)
+		return ret;
+
+	/* 1.983µV/RSNSI amperes per LSB */
+	ret = regval * 19830;
+	ret /= info->rsnsi;
+	ret *= 100;
+
+	val->intval = ret;
+
+	return 0;
+}
+
+static int ltc3350_get_icharge(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_ICHG, &regval);
+	if (ret)
+		return ret;
+
+	/* 1.983µV/RSNSC amperes per LSB */
+	ret = regval * 19830;
+	ret /= info->rsnsc;
+	ret *= 100;
+
+	val->intval = ret;
+
+	return 0;
+}
+
+static int ltc3350_get_icharge_max(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	/* I_CHG(MAX) = 32mV / RSNSC (Ampere) */
+	val->intval = 3200000000U / (info->rsnsc / 10);
+
+	return 0;
+}
+
+static int ltc3350_get_iin_max(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	/* I_IN(MAX) = 32mV / RSNSI (Ampere) */
+	val->intval = 3200000000U / (info->rsnsi / 10);
+
+	return 0;
+}
+
+
+static int ltc3350_get_die_temp(struct ltc3350_info *info, unsigned int reg,
+				union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	/* 0.028°C per LSB – 251.4°C */
+	ret = 280 * regval;
+	ret /= 100; /* Centidegrees scale */
+	ret -= 25140;
+	val->intval = ret;
+
+	return 0;
+}
+
+static int ltc3350_set_die_temp(struct ltc3350_info *info, unsigned int reg, int val)
+{
+	unsigned int regval;
+	int ret;
+
+	/* 0.028°C per LSB – 251.4°C */
+	regval = val + 25140;
+	regval *= 100;
+	regval /= 280;
+
+	ret = regmap_write(info->regmap, reg, regval);
+	if (ret)
+		return ret;
+
+	ltc3350_enable_alarm(info, reg);
+	return 0;
+}
+
+/* Custom properties */
+
+static ssize_t ltc3350_attr_show(struct device *dev,
+				 struct device_attribute *attr, char *buf,
+				 unsigned int reg, unsigned int scale)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	regval *= scale; /* Scale is in 10 μV units */
+	regval /= 10;
+
+	return sprintf(buf, "%u\n", regval);
+}
+
+static ssize_t ltc3350_attr_store(struct device *dev, struct device_attribute *attr,
+				  const char *buf, size_t count,
+				  unsigned int reg, unsigned int scale)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	val *= 10;
+	val = DIV_ROUND_CLOSEST(val, scale); /* Scale is in 10 μV units */
+
+	ret = regmap_write(info->regmap, reg, val);
+	if (ret)
+		return ret;
+
+	/* When writing to one of the LVL registers, update the alarm mask */
+	if (reg >= LTC3350_REG_CAP_UV_LVL && reg <= LTC3350_REG_CAP_LO_LVL)
+		ltc3350_enable_alarm(info, reg);
+
+	return count;
+}
+
+#define LTC3350_DEVICE_ATTR_RO(_name, _reg, _scale)				\
+static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
+			    char *buf)						\
+{										\
+	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
+}										\
+static DEVICE_ATTR_RO(_name)
+
+#define LTC3350_DEVICE_ATTR_RW(_name, _reg, _scale)				\
+static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
+			    char *buf)						\
+{										\
+	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
+}										\
+static ssize_t _name##_store(struct device *dev, struct device_attribute *attr, \
+			     const char *buf, size_t count)			\
+{										\
+	return ltc3350_attr_store(dev, attr, buf, count, _reg, _scale);		\
+}										\
+static DEVICE_ATTR_RW(_name)
+
+/* Shunt voltage, 183.5μV per LSB */
+LTC3350_DEVICE_ATTR_RW(vshunt, LTC3350_REG_VSHUNT, 1835);
+
+/* Single capacitor voltages, 183.5μV per LSB */
+LTC3350_DEVICE_ATTR_RO(vcap1, LTC3350_REG_MEAS_VCAP1, 1835);
+LTC3350_DEVICE_ATTR_RO(vcap2, LTC3350_REG_MEAS_VCAP2, 1835);
+LTC3350_DEVICE_ATTR_RO(vcap3, LTC3350_REG_MEAS_VCAP3, 1835);
+LTC3350_DEVICE_ATTR_RO(vcap4, LTC3350_REG_MEAS_VCAP4, 1835);
+LTC3350_DEVICE_ATTR_RW(cap_uv, LTC3350_REG_CAP_UV_LVL, 1835);
+LTC3350_DEVICE_ATTR_RW(cap_ov, LTC3350_REG_CAP_OV_LVL, 1835);
+
+/* General purpose input, 183.5μV per LSB */
+LTC3350_DEVICE_ATTR_RO(gpi, LTC3350_REG_MEAS_GPI, 1835);
+LTC3350_DEVICE_ATTR_RW(gpi_uv, LTC3350_REG_GPI_UV_LVL, 1835);
+LTC3350_DEVICE_ATTR_RW(gpi_ov, LTC3350_REG_GPI_OV_LVL, 1835);
+
+/* Input voltage, 2.21mV per LSB */
+LTC3350_DEVICE_ATTR_RO(vin, LTC3350_REG_MEAS_VIN, 22100);
+LTC3350_DEVICE_ATTR_RW(vin_uv, LTC3350_REG_VIN_UV_LVL, 22100);
+LTC3350_DEVICE_ATTR_RW(vin_ov, LTC3350_REG_VIN_OV_LVL, 22100);
+
+/* Capacitor stack voltage, 1.476 mV per LSB */
+LTC3350_DEVICE_ATTR_RO(vcap, LTC3350_REG_MEAS_VCAP, 14760);
+LTC3350_DEVICE_ATTR_RW(vcap_uv, LTC3350_REG_VCAP_UV_LVL, 14760);
+LTC3350_DEVICE_ATTR_RW(vcap_ov, LTC3350_REG_VCAP_OV_LVL, 14760);
+
+/* Output, 2.21mV per LSB */
+LTC3350_DEVICE_ATTR_RO(vout, LTC3350_REG_MEAS_VOUT, 22100);
+LTC3350_DEVICE_ATTR_RW(vout_uv, LTC3350_REG_VOUT_UV_LVL, 22100);
+LTC3350_DEVICE_ATTR_RW(vout_ov, LTC3350_REG_VOUT_OV_LVL, 22100);
+
+static ssize_t num_caps_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_NUM_CAPS, &regval);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "%u\n", regval + 1);
+}
+static DEVICE_ATTR_RO(num_caps);
+
+static ssize_t charge_status_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "0x%x\n", regval);
+}
+static DEVICE_ATTR_RO(charge_status);
+
+static struct attribute *ltc3350_sysfs_entries[] = {
+	&dev_attr_vshunt.attr,
+	&dev_attr_vcap1.attr,
+	&dev_attr_vcap2.attr,
+	&dev_attr_vcap3.attr,
+	&dev_attr_vcap4.attr,
+	&dev_attr_cap_uv.attr,
+	&dev_attr_cap_ov.attr,
+	&dev_attr_gpi.attr,
+	&dev_attr_gpi_uv.attr,
+	&dev_attr_gpi_ov.attr,
+	&dev_attr_vin_uv.attr,
+	&dev_attr_vin_ov.attr,
+	&dev_attr_vcap.attr,
+	&dev_attr_vcap_uv.attr,
+	&dev_attr_vcap_ov.attr,
+	&dev_attr_vin.attr,
+	&dev_attr_vin_uv.attr,
+	&dev_attr_vin_ov.attr,
+	&dev_attr_vout.attr,
+	&dev_attr_vout_uv.attr,
+	&dev_attr_vout_ov.attr,
+	&dev_attr_num_caps.attr,
+	&dev_attr_charge_status.attr,
+	NULL,
+};
+
+static const struct attribute_group ltc3350_attr_group = {
+	.name	= NULL,	/* put in device directory */
+	.attrs	= ltc3350_sysfs_entries,
+};
+
+static const struct attribute_group *ltc3350_attr_groups[] = {
+	&ltc3350_attr_group,
+	NULL,
+};
+
+static int ltc3350_get_property(struct power_supply *psy, enum power_supply_property psp,
+				union power_supply_propval *val)
+{
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		return ltc3350_get_status(info, val);
+	case POWER_SUPPLY_PROP_CHARGE_TYPE:
+		return ltc3350_get_charge_type(info, val);
+	case POWER_SUPPLY_PROP_ONLINE:
+		return ltc3350_get_online(info, val);
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		return ltc3350_get_input_voltage(info, val);
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		return ltc3350_get_input_current(info, val);
+	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
+		return ltc3350_get_icharge(info, val);
+	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
+		return ltc3350_get_icharge_max(info, val);
+	case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+		return ltc3350_get_iin_max(info, val);
+	case POWER_SUPPLY_PROP_TEMP:
+		return ltc3350_get_die_temp(info, LTC3350_REG_MEAS_DTEMP, val);
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+		return ltc3350_get_die_temp(info, LTC3350_REG_DTEMP_COLD_LVL, val);
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		return ltc3350_get_die_temp(info, LTC3350_REG_DTEMP_HOT_LVL, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ltc3350_set_property(struct power_supply *psy, enum power_supply_property psp,
+				const union power_supply_propval *val)
+{
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+		return ltc3350_set_die_temp(info, LTC3350_REG_DTEMP_COLD_LVL, val->intval);
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		return ltc3350_set_die_temp(info, LTC3350_REG_DTEMP_HOT_LVL, val->intval);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ltc3350_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;
+	}
+}
+
+/* Charger power supply property routines */
+static enum power_supply_property ltc3350_properties[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_CHARGE_TYPE,
+	POWER_SUPPLY_PROP_ONLINE,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT,
+	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX,
+	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_TEMP_ALERT_MIN,
+	POWER_SUPPLY_PROP_TEMP_ALERT_MAX,
+};
+
+static const struct power_supply_desc ltc3350_desc = {
+	.name		= "ltc3350",
+	.type		= POWER_SUPPLY_TYPE_MAINS,
+	.properties	= ltc3350_properties,
+	.num_properties	= ARRAY_SIZE(ltc3350_properties),
+	.get_property	= ltc3350_get_property,
+	.set_property	= ltc3350_set_property,
+	.property_is_writeable = ltc3350_property_is_writeable,
+};
+
+static bool ltc3350_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	/* all registers up to this one are writeable */
+	return reg < LTC3350_REG_NUM_CAPS;
+}
+
+static bool ltc3350_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	/* read-only status registers and self-clearing register */
+	return reg > LTC3350_REG_NUM_CAPS || reg == LTC3350_REG_CLR_ALARMS;
+}
+
+static const struct regmap_config ltc3350_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 16,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+	.writeable_reg	= ltc3350_is_writeable_reg,
+	.volatile_reg	= ltc3350_is_volatile_reg,
+	.max_register	= LTC3350_REG_MEAS_DTEMP,
+	.cache_type	= REGCACHE_MAPLE,
+};
+
+static int ltc3350_probe(struct i2c_client *client)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct device *dev = &client->dev;
+	struct ltc3350_info *info;
+	struct power_supply_config ltc3350_config = {};
+	int ret;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
+		dev_err(dev, "No support for SMBUS_WORD_DATA\n");
+		return -ENODEV;
+	}
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->client = client;
+	i2c_set_clientdata(client, info);
+
+	info->regmap = devm_regmap_init_i2c(client, &ltc3350_regmap_config);
+	if (IS_ERR(info->regmap)) {
+		dev_err(dev, "Failed to initialize register map\n");
+		return PTR_ERR(info->regmap);
+	}
+
+	ret = device_property_read_u32(dev, "lltc,rsnsc-micro-ohms",
+				       &info->rsnsc);
+	if (ret) {
+		dev_err(dev, "Missing lltc,rsnsc-micro-ohms property\n");
+		return ret;
+	}
+	if (!info->rsnsc)
+		return -EINVAL;
+
+	ret = device_property_read_u32(dev, "lltc,rsnsi-micro-ohms",
+				       &info->rsnsi);
+	if (ret) {
+		dev_err(dev, "Missing lltc,rsnsi-micro-ohms property\n");
+		return ret;
+	}
+	if (!info->rsnsi)
+		return -EINVAL;
+
+	/* Clear and disable all interrupt sources*/
+	ret = regmap_write(info->regmap, LTC3350_REG_CLR_ALARMS, 0xFFFF);
+	if (ret) {
+		dev_err(dev, "Failed to write configuration\n");
+		return ret;
+	}
+	regmap_write(info->regmap, LTC3350_REG_MSK_ALARMS, 0);
+	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS, 0);
+
+	ltc3350_config.of_node = dev->of_node;
+	ltc3350_config.drv_data = info;
+	ltc3350_config.attr_grp = ltc3350_attr_groups;
+
+	info->charger = devm_power_supply_register(dev, &ltc3350_desc,
+						   &ltc3350_config);
+	if (IS_ERR(info->charger)) {
+		dev_err(dev, "Failed to register charger\n");
+		return PTR_ERR(info->charger);
+	}
+
+	/* Enable interrupts on status changes */
+	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS,
+		     LTC3350_MON_POWER_FAILED | LTC3350_MON_POWER_RETURNED);
+
+	return 0;
+}
+
+static void ltc3350_alert(struct i2c_client *client, enum i2c_alert_protocol type,
+			  unsigned int flag)
+{
+	struct ltc3350_info *info = i2c_get_clientdata(client);
+
+	if (type != I2C_PROTOCOL_SMBUS_ALERT)
+		return;
+
+	power_supply_changed(info->charger);
+}
+
+static const struct i2c_device_id ltc3350_i2c_id_table[] = {
+	{ "ltc3350", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, ltc3350_i2c_id_table);
+
+static const struct of_device_id ltc3350_of_match[] = {
+	{ .compatible = "lltc,ltc3350", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ltc3350_of_match);
+
+static struct i2c_driver ltc3350_driver = {
+	.probe		= ltc3350_probe,
+	.alert		= ltc3350_alert,
+	.id_table	= ltc3350_i2c_id_table,
+	.driver = {
+		.name		= "ltc3350-charger",
+		.of_match_table	= of_match_ptr(ltc3350_of_match),
+	},
+};
+module_i2c_driver(ltc3350_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mike Looijmans <mike.looijmans@...ic.nl>");
+MODULE_DESCRIPTION("LTC3350 charger driver");
-- 
2.34.1


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@...ic.nl
W: www.topic.nl

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