hwmon: Add support for ltc2947

The ltc2947 is a high precision power and energy monitor with an
internal sense resistor supporting up to +/- 30A. Three internal no
Latency ADCs ensure accurate measurement of voltage and current, while
high-bandwidth analog multiplication of voltage and current provides
accurate power measurement in a wide range of applications. Internal or
external clocking options enable precise charge and energy measurements.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20191021154115.319073-1-nuno.sa@analog.com
[groeck: Removed unnecessary checks when reading temperature and energy;
	 PAGE{0,1} -> LTC2947_PAGE_{0,1}]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

9 files changed, 1435 insertions, 0 deletions

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 230ad59b462b..dad3bf4ebf63 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -90,6 +90,7 @@ Hardware Monitoring Kernel Drivers
    lm95245
    lochnagar
    ltc2945
+   ltc2947
    ltc2978
    ltc2990
    ltc3815
diff --git a/Documentation/hwmon/ltc2947.rst b/Documentation/hwmon/ltc2947.rst
new file mode 100644
index 000000000000..419fc84fe934
--- /dev/null
+++ b/Documentation/hwmon/ltc2947.rst
@@ -0,0 +1,100 @@
+Kernel drivers ltc2947-i2c and ltc2947-spi
+==========================================
+
+Supported chips:
+
+  * Analog Devices LTC2947
+
+    Prefix: 'ltc2947'
+
+    Addresses scanned: -
+
+    Datasheet:
+
+        https://www.analog.com/media/en/technical-documentation/data-sheets/LTC2947.pdf
+
+Author: Nuno Sá <nuno.sa@analog.com>
+
+Description
+___________
+
+The LTC2947 is a high precision power and energy monitor that measures current,
+voltage, power, temperature, charge and energy. The device supports both SPI
+and I2C depending on the chip configuration.
+The device also measures accumulated quantities as energy. It has two banks of
+register's to read/set energy related values. These banks can be configured
+independently to have setups like: energy1 accumulates always and enrgy2 only
+accumulates if current is positive (to check battery charging efficiency for
+example). The device also supports a GPIO pin that can be configured as output
+to control a fan as a function of measured temperature. Then, the GPIO becomes
+active as soon as a temperature reading is higher than a defined threshold. The
+temp2 channel is used to control this thresholds and to read the respective
+alarms.
+
+Sysfs entries
+_____________
+
+The following attributes are supported. Limits are read-write, reset_history
+is write-only and all the other attributes are read-only.
+
+======================= ==========================================
+in0_input		VP-VM voltage (mV).
+in0_min			Undervoltage threshold
+in0_max			Overvoltage threshold
+in0_lowest		Lowest measured voltage
+in0_highest		Highest measured voltage
+in0_reset_history	Write 1 to reset in1 history
+in0_min_alarm		Undervoltage alarm
+in0_max_alarm		Overvoltage alarm
+in0_label		Channel label (VP-VM)
+
+in1_input		DVCC voltage (mV)
+in1_min			Undervoltage threshold
+in1_max			Overvoltage threshold
+in1_lowest		Lowest measured voltage
+in1_highest		Highest measured voltage
+in1_reset_history	Write 1 to reset in2 history
+in1_min_alarm		Undervoltage alarm
+in1_max_alarm		Overvoltage alarm
+in1_label		Channel label (DVCC)
+
+curr1_input		IP-IM Sense current (mA)
+curr1_min		Undercurrent threshold
+curr1_max		Overcurrent threshold
+curr1_lowest		Lowest measured current
+curr1_highest		Highest measured current
+curr1_reset_history	Write 1 to reset curr1 history
+curr1_min_alarm		Undercurrent alarm
+curr1_max_alarm		Overcurrent alarm
+curr1_label		Channel label (IP-IM)
+
+power1_input		Power (in uW)
+power1_min		Low power threshold
+power1_max		High power threshold
+power1_input_lowest	Historical minimum power use
+power1_input_highest	Historical maximum power use
+power1_reset_history	Write 1 to reset power1 history
+power1_min_alarm	Low power alarm
+power1_max_alarm	High power alarm
+power1_label		Channel label (Power)
+
+temp1_input		Chip Temperature (in milliC)
+temp1_min		Low temperature threshold
+temp1_max		High temperature threshold
+temp1_input_lowest	Historical minimum temperature use
+temp1_input_highest	Historical maximum temperature use
+temp1_reset_history	Write 1 to reset temp1 history
+temp1_min_alarm		Low temperature alarm
+temp1_max_alarm		High temperature alarm
+temp1_label		Channel label (Ambient)
+
+temp2_min		Low temperature threshold for fan control
+temp2_max		High temperature threshold for fan control
+temp2_min_alarm		Low temperature fan control alarm
+temp2_max_alarm		High temperature fan control alarm
+temp2_label		Channel label (TEMPFAN)
+
+energy1_input		Measured energy over time (in microJoule)
+
+energy2_input		Measured energy over time (in microJoule)
+======================= ==========================================
diff --git a/MAINTAINERS b/MAINTAINERS
index cba1095547fd..7dd64009e183 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9630,6 +9630,16 @@ S:	Maintained
 F:	Documentation/hwmon/ltc4261.rst
 F:	drivers/hwmon/ltc4261.c
 
+LTC2947 HARDWARE MONITOR DRIVER
+M:	Nuno Sá <nuno.sa@analog.com>
+W:	http://ez.analog.com/community/linux-device-drivers
+L:	linux-hwmon@vger.kernel.org
+S:	Supported
+F:	drivers/hwmon/ltc2947-core.c
+F:	drivers/hwmon/ltc2947-spi.c
+F:	drivers/hwmon/ltc2947-i2c.c
+F:	drivers/hwmon/ltc2947.h
+
 LTC4306 I2C MULTIPLEXER DRIVER
 M:	Michael Hennerich <michael.hennerich@analog.com>
 W:	http://ez.analog.com/community/linux-device-drivers
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 7b6c4025b827..8c102ea2938b 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -726,6 +726,33 @@ config SENSORS_LTC2945
 	  This driver can also be built as a module. If so, the module will
 	  be called ltc2945.
 
+config SENSORS_LTC2947
+	tristate
+
+config SENSORS_LTC2947_I2C
+	tristate "Analog Devices LTC2947 High Precision Power and Energy Monitor over I2C"
+	depends on I2C
+	select REGMAP_I2C
+	select SENSORS_LTC2947
+	help
+	  If you say yes here you get support for Linear Technology LTC2947
+	  I2C High Precision Power and Energy Monitor
+
+	  This driver can also be built as a module. If so, the module will
+	  be called ltc2947-i2c.
+
+config SENSORS_LTC2947_SPI
+	tristate "Analog Devices LTC2947 High Precision Power and Energy Monitor over SPI"
+	depends on SPI_MASTER
+	select REGMAP_SPI
+	select SENSORS_LTC2947
+	help
+	  If you say yes here you get support for Linear Technology LTC2947
+	  SPI High Precision Power and Energy Monitor
+
+	  This driver can also be built as a module. If so, the module will
+	  be called ltc2947-spi.
+
 config SENSORS_LTC2990
 	tristate "Linear Technology LTC2990"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 40c036ea45e6..e416cfded0c4 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -106,6 +106,9 @@ obj-$(CONFIG_SENSORS_LM95234)	+= lm95234.o
 obj-$(CONFIG_SENSORS_LM95241)	+= lm95241.o
 obj-$(CONFIG_SENSORS_LM95245)	+= lm95245.o
 obj-$(CONFIG_SENSORS_LTC2945)	+= ltc2945.o
+obj-$(CONFIG_SENSORS_LTC2947)	+= ltc2947-core.o
+obj-$(CONFIG_SENSORS_LTC2947_I2C) += ltc2947-i2c.o
+obj-$(CONFIG_SENSORS_LTC2947_SPI) += ltc2947-spi.o
 obj-$(CONFIG_SENSORS_LTC2990)	+= ltc2990.o
 obj-$(CONFIG_SENSORS_LTC4151)	+= ltc4151.o
 obj-$(CONFIG_SENSORS_LTC4215)	+= ltc4215.o
diff --git a/drivers/hwmon/ltc2947-core.c b/drivers/hwmon/ltc2947-core.c
new file mode 100644
index 000000000000..bb3f7749a0b0
--- /dev/null
+++ b/drivers/hwmon/ltc2947-core.c
@@ -0,0 +1,1183 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices LTC2947 high precision power and energy monitor
+ *
+ * Copyright 2019 Analog Devices Inc.
+ */
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+#include "ltc2947.h"
+
+/* register's */
+#define LTC2947_REG_PAGE_CTRL		0xFF
+#define LTC2947_REG_CTRL		0xF0
+#define LTC2947_REG_TBCTL		0xE9
+#define LTC2947_CONT_MODE_MASK		BIT(3)
+#define LTC2947_CONT_MODE(x)		FIELD_PREP(LTC2947_CONT_MODE_MASK, x)
+#define LTC2947_PRE_MASK		GENMASK(2, 0)
+#define LTC2947_PRE(x)			FIELD_PREP(LTC2947_PRE_MASK, x)
+#define LTC2947_DIV_MASK		GENMASK(7, 3)
+#define LTC2947_DIV(x)			FIELD_PREP(LTC2947_DIV_MASK, x)
+#define LTC2947_SHUTDOWN_MASK		BIT(0)
+#define LTC2947_REG_ACCUM_POL		0xE1
+#define LTC2947_ACCUM_POL_1_MASK	GENMASK(1, 0)
+#define LTC2947_ACCUM_POL_1(x)		FIELD_PREP(LTC2947_ACCUM_POL_1_MASK, x)
+#define LTC2947_ACCUM_POL_2_MASK	GENMASK(3, 2)
+#define LTC2947_ACCUM_POL_2(x)		FIELD_PREP(LTC2947_ACCUM_POL_2_MASK, x)
+#define LTC2947_REG_ACCUM_DEADBAND	0xE4
+#define LTC2947_REG_GPIOSTATCTL		0x67
+#define LTC2947_GPIO_EN_MASK		BIT(0)
+#define LTC2947_GPIO_EN(x)		FIELD_PREP(LTC2947_GPIO_EN_MASK, x)
+#define LTC2947_GPIO_FAN_EN_MASK	BIT(6)
+#define LTC2947_GPIO_FAN_EN(x)		FIELD_PREP(LTC2947_GPIO_FAN_EN_MASK, x)
+#define LTC2947_GPIO_FAN_POL_MASK	BIT(7)
+#define LTC2947_GPIO_FAN_POL(x)		FIELD_PREP(LTC2947_GPIO_FAN_POL_MASK, x)
+#define LTC2947_REG_GPIO_ACCUM		0xE3
+/* 200Khz */
+#define LTC2947_CLK_MIN			200000
+/* 25Mhz */
+#define LTC2947_CLK_MAX			25000000
+#define LTC2947_PAGE0			0
+#define LTC2947_PAGE1			1
+/* Voltage registers */
+#define LTC2947_REG_VOLTAGE		0xA0
+#define LTC2947_REG_VOLTAGE_MAX		0x50
+#define LTC2947_REG_VOLTAGE_MIN		0x52
+#define LTC2947_REG_VOLTAGE_THRE_H	0x90
+#define LTC2947_REG_VOLTAGE_THRE_L	0x92
+#define LTC2947_REG_DVCC		0xA4
+#define LTC2947_REG_DVCC_MAX		0x58
+#define LTC2947_REG_DVCC_MIN		0x5A
+#define LTC2947_REG_DVCC_THRE_H		0x98
+#define LTC2947_REG_DVCC_THRE_L		0x9A
+#define LTC2947_VOLTAGE_GEN_CHAN	0
+#define LTC2947_VOLTAGE_DVCC_CHAN	1
+/* in mV */
+#define VOLTAGE_MAX			15500
+#define VOLTAGE_MIN			-300
+#define VDVCC_MAX			15000
+#define VDVCC_MIN			4750
+/* Current registers */
+#define LTC2947_REG_CURRENT		0x90
+#define LTC2947_REG_CURRENT_MAX		0x40
+#define LTC2947_REG_CURRENT_MIN		0x42
+#define LTC2947_REG_CURRENT_THRE_H	0x80
+#define LTC2947_REG_CURRENT_THRE_L	0x82
+/* in mA */
+#define CURRENT_MAX			30000
+#define CURRENT_MIN			-30000
+/* Power registers */
+#define LTC2947_REG_POWER		0x93
+#define LTC2947_REG_POWER_MAX		0x44
+#define LTC2947_REG_POWER_MIN		0x46
+#define LTC2947_REG_POWER_THRE_H	0x84
+#define LTC2947_REG_POWER_THRE_L	0x86
+/* in uW */
+#define POWER_MAX			450000000
+#define POWER_MIN			-450000000
+/* Temperature registers */
+#define LTC2947_REG_TEMP		0xA2
+#define LTC2947_REG_TEMP_MAX		0x54
+#define LTC2947_REG_TEMP_MIN		0x56
+#define LTC2947_REG_TEMP_THRE_H		0x94
+#define LTC2947_REG_TEMP_THRE_L		0x96
+#define LTC2947_REG_TEMP_FAN_THRE_H	0x9C
+#define LTC2947_REG_TEMP_FAN_THRE_L	0x9E
+#define LTC2947_TEMP_FAN_CHAN		1
+/* in millidegress Celsius */
+#define TEMP_MAX			85000
+#define TEMP_MIN			-40000
+/* Energy registers */
+#define LTC2947_REG_ENERGY1		0x06
+#define LTC2947_REG_ENERGY2		0x16
+/* Status/Alarm/Overflow registers */
+#define LTC2947_REG_STATUS		0x80
+#define LTC2947_REG_STATVT		0x81
+#define LTC2947_REG_STATIP		0x82
+#define LTC2947_REG_STATVDVCC		0x87
+
+#define LTC2947_ALERTS_SIZE	(LTC2947_REG_STATVDVCC - LTC2947_REG_STATUS)
+#define LTC2947_MAX_VOLTAGE_MASK	BIT(0)
+#define LTC2947_MIN_VOLTAGE_MASK	BIT(1)
+#define LTC2947_MAX_CURRENT_MASK	BIT(0)
+#define LTC2947_MIN_CURRENT_MASK	BIT(1)
+#define LTC2947_MAX_POWER_MASK		BIT(2)
+#define LTC2947_MIN_POWER_MASK		BIT(3)
+#define LTC2947_MAX_TEMP_MASK		BIT(2)
+#define LTC2947_MIN_TEMP_MASK		BIT(3)
+#define LTC2947_MAX_TEMP_FAN_MASK	BIT(4)
+#define LTC2947_MIN_TEMP_FAN_MASK	BIT(5)
+
+struct ltc2947_data {
+	struct regmap *map;
+	struct device *dev;
+	/*
+	 * The mutex is needed because the device has 2 memory pages. When
+	 * reading/writing the correct page needs to be set so that, the
+	 * complete sequence select_page->read/write needs to be protected.
+	 */
+	struct mutex lock;
+	u32 lsb_energy;
+	bool gpio_out;
+};
+
+static int __ltc2947_val_read16(const struct ltc2947_data *st, const u8 reg,
+				u64 *val)
+{
+	__be16 __val = 0;
+	int ret;
+
+	ret = regmap_bulk_read(st->map, reg, &__val, 2);
+	if (ret)
+		return ret;
+
+	*val = be16_to_cpu(__val);
+
+	return 0;
+}
+
+static int __ltc2947_val_read24(const struct ltc2947_data *st, const u8 reg,
+				u64 *val)
+{
+	__be32 __val = 0;
+	int ret;
+
+	ret = regmap_bulk_read(st->map, reg, &__val, 3);
+	if (ret)
+		return ret;
+
+	*val = be32_to_cpu(__val) >> 8;
+
+	return 0;
+}
+
+static int __ltc2947_val_read64(const struct ltc2947_data *st, const u8 reg,
+				u64 *val)
+{
+	__be64 __val = 0;
+	int ret;
+
+	ret = regmap_bulk_read(st->map, reg, &__val, 6);
+	if (ret)
+		return ret;
+
+	*val = be64_to_cpu(__val) >> 16;
+
+	return 0;
+}
+
+static int ltc2947_val_read(struct ltc2947_data *st, const u8 reg,
+			    const u8 page, const size_t size, s64 *val)
+{
+	int ret;
+	u64 __val = 0;
+
+	mutex_lock(&st->lock);
+
+	ret = regmap_write(st->map, LTC2947_REG_PAGE_CTRL, page);
+	if (ret) {
+		mutex_unlock(&st->lock);
+		return ret;
+	}
+
+	dev_dbg(st->dev, "Read val, reg:%02X, p:%d sz:%zu\n", reg, page,
+		size);
+
+	switch (size) {
+	case 2:
+		ret = __ltc2947_val_read16(st, reg, &__val);
+		break;
+	case 3:
+		ret = __ltc2947_val_read24(st, reg, &__val);
+		break;
+	case 6:
+		ret = __ltc2947_val_read64(st, reg, &__val);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	mutex_unlock(&st->lock);
+
+	if (ret)
+		return ret;
+
+	*val = sign_extend64(__val, (8 * size) - 1);
+
+	dev_dbg(st->dev, "Got s:%lld, u:%016llX\n", *val, __val);
+
+	return 0;
+}
+
+static int __ltc2947_val_write64(const struct ltc2947_data *st, const u8 reg,
+				 const u64 val)
+{
+	__be64 __val;
+
+	__val = cpu_to_be64(val << 16);
+	return regmap_bulk_write(st->map, reg, &__val, 6);
+}
+
+static int __ltc2947_val_write16(const struct ltc2947_data *st, const u8 reg,
+				 const u16 val)
+{
+	__be16 __val;
+
+	__val = cpu_to_be16(val);
+	return regmap_bulk_write(st->map, reg, &__val, 2);
+}
+
+static int ltc2947_val_write(struct ltc2947_data *st, const u8 reg,
+			     const u8 page, const size_t size, const u64 val)
+{
+	int ret;
+
+	mutex_lock(&st->lock);
+	/* set device on correct page */
+	ret = regmap_write(st->map, LTC2947_REG_PAGE_CTRL, page);
+	if (ret) {
+		mutex_unlock(&st->lock);
+		return ret;
+	}
+
+	dev_dbg(st->dev, "Write val, r:%02X, p:%d, sz:%zu, val:%016llX\n",
+		reg, page, size, val);
+
+	switch (size) {
+	case 2:
+		ret = __ltc2947_val_write16(st, reg, val);
+		break;
+	case 6:
+		ret = __ltc2947_val_write64(st, reg, val);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int ltc2947_reset_history(struct ltc2947_data *st, const u8 reg_h,
+				 const u8 reg_l)
+{
+	int ret;
+	/*
+	 * let's reset the tracking register's. Tracking register's have all
+	 * 2 bytes size
+	 */
+	ret = ltc2947_val_write(st, reg_h, LTC2947_PAGE0, 2, 0x8000U);
+	if (ret)
+		return ret;
+
+	return ltc2947_val_write(st, reg_l, LTC2947_PAGE0, 2, 0x7FFFU);
+}
+
+static int ltc2947_alarm_read(struct ltc2947_data *st, const u8 reg,
+			      const u32 mask, long *val)
+{
+	u8 offset = reg - LTC2947_REG_STATUS;
+	/* +1 to include status reg */
+	char alarms[LTC2947_ALERTS_SIZE + 1];
+	int ret = 0;
+
+	memset(alarms, 0, sizeof(alarms));
+
+	mutex_lock(&st->lock);
+
+	ret = regmap_write(st->map, LTC2947_REG_PAGE_CTRL, LTC2947_PAGE0);
+	if (ret)
+		goto unlock;
+
+	dev_dbg(st->dev, "Read alarm, reg:%02X, mask:%02X\n", reg, mask);
+	/*
+	 * As stated in the datasheet, when Threshold and Overflow registers
+	 * are used, the status and all alert registers must be read in one
+	 * multi-byte transaction.
+	 */
+	ret = regmap_bulk_read(st->map, LTC2947_REG_STATUS, alarms,
+			       sizeof(alarms));
+	if (ret)
+		goto unlock;
+
+	/* get the alarm */
+	*val = !!(alarms[offset] & mask);
+unlock:
+	mutex_unlock(&st->lock);
+	return ret;
+}
+
+static ssize_t ltc2947_show_value(struct device *dev,
+				  struct device_attribute *da, char *buf)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	int ret;
+	s64 val = 0;
+
+	ret = ltc2947_val_read(st, attr->index, LTC2947_PAGE0, 6, &val);
+	if (ret)
+		return ret;
+
+	/* value in microJoule. st->lsb_energy was multiplied by 10E9 */
+	val = div_s64(val * st->lsb_energy, 1000);
+
+	return sprintf(buf, "%lld\n", val);
+}
+
+static int ltc2947_read_temp(struct device *dev, const u32 attr, long *val,
+			     const int channel)
+{
+	int ret;
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+	s64 __val = 0;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		ret = ltc2947_val_read(st, LTC2947_REG_TEMP, LTC2947_PAGE0,
+				       2, &__val);
+		break;
+	case hwmon_temp_highest:
+		ret = ltc2947_val_read(st, LTC2947_REG_TEMP_MAX, LTC2947_PAGE0,
+				       2, &__val);
+		break;
+	case hwmon_temp_lowest:
+		ret = ltc2947_val_read(st, LTC2947_REG_TEMP_MIN, LTC2947_PAGE0,
+				       2, &__val);
+		break;
+	case hwmon_temp_max_alarm:
+		if (channel == LTC2947_TEMP_FAN_CHAN)
+			return ltc2947_alarm_read(st, LTC2947_REG_STATVT,
+						  LTC2947_MAX_TEMP_FAN_MASK,
+						  val);
+
+		return ltc2947_alarm_read(st, LTC2947_REG_STATVT,
+					  LTC2947_MAX_TEMP_MASK, val);
+	case hwmon_temp_min_alarm:
+		if (channel == LTC2947_TEMP_FAN_CHAN)
+			return	ltc2947_alarm_read(st, LTC2947_REG_STATVT,
+						   LTC2947_MIN_TEMP_FAN_MASK,
+						   val);
+
+		return	ltc2947_alarm_read(st, LTC2947_REG_STATVT,
+					   LTC2947_MIN_TEMP_MASK, val);
+	case hwmon_temp_max:
+		if (channel == LTC2947_TEMP_FAN_CHAN)
+			ret = ltc2947_val_read(st, LTC2947_REG_TEMP_FAN_THRE_H,
+					       LTC2947_PAGE1, 2, &__val);
+		else
+			ret = ltc2947_val_read(st, LTC2947_REG_TEMP_THRE_H,
+					       LTC2947_PAGE1, 2, &__val);
+		break;
+	case hwmon_temp_min:
+		if (channel == LTC2947_TEMP_FAN_CHAN)
+			ret = ltc2947_val_read(st, LTC2947_REG_TEMP_FAN_THRE_L,
+					       LTC2947_PAGE1, 2, &__val);
+		else
+			ret = ltc2947_val_read(st, LTC2947_REG_TEMP_THRE_L,
+					       LTC2947_PAGE1, 2, &__val);
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	if (ret)
+		return ret;
+
+	/* in milidegrees celcius, temp is given by: */
+	*val = (__val * 204) + 550;
+
+	return 0;
+}
+
+static int ltc2947_read_power(struct device *dev, const u32 attr, long *val)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+	int ret;
+	u32 lsb = 200000; /* in uW */
+	s64 __val = 0;
+
+	switch (attr) {
+	case hwmon_power_input:
+		ret = ltc2947_val_read(st, LTC2947_REG_POWER, LTC2947_PAGE0,
+				       3, &__val);
+		lsb = 50000;
+		break;
+	case hwmon_power_input_highest:
+		ret = ltc2947_val_read(st, LTC2947_REG_POWER_MAX, LTC2947_PAGE0,
+				       2, &__val);
+		break;
+	case hwmon_power_input_lowest:
+		ret = ltc2947_val_read(st, LTC2947_REG_POWER_MIN, LTC2947_PAGE0,
+				       2, &__val);
+		break;
+	case hwmon_power_max_alarm:
+		return ltc2947_alarm_read(st, LTC2947_REG_STATIP,
+					  LTC2947_MAX_POWER_MASK, val);
+	case hwmon_power_min_alarm:
+		return ltc2947_alarm_read(st, LTC2947_REG_STATIP,
+					  LTC2947_MIN_POWER_MASK, val);
+	case hwmon_power_max:
+		ret = ltc2947_val_read(st, LTC2947_REG_POWER_THRE_H,
+				       LTC2947_PAGE1, 2, &__val);
+		break;
+	case hwmon_power_min:
+		ret = ltc2947_val_read(st, LTC2947_REG_POWER_THRE_L,
+				       LTC2947_PAGE1, 2, &__val);
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	if (ret)
+		return ret;
+
+	*val = __val * lsb;
+
+	return 0;
+}
+
+static int ltc2947_read_curr(struct device *dev, const u32 attr, long *val)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+	int ret;
+	u8 lsb = 12; /* in mA */
+	s64 __val = 0;
+
+	switch (attr) {
+	case hwmon_curr_input:
+		ret = ltc2947_val_read(st, LTC2947_REG_CURRENT,
+				       LTC2947_PAGE0, 3, &__val);
+		lsb = 3;
+		break;
+	case hwmon_curr_highest:
+		ret = ltc2947_val_read(st, LTC2947_REG_CURRENT_MAX,
+				       LTC2947_PAGE0, 2, &__val);
+		break;
+	case hwmon_curr_lowest:
+		ret = ltc2947_val_read(st, LTC2947_REG_CURRENT_MIN,
+				       LTC2947_PAGE0, 2, &__val);
+		break;
+	case hwmon_curr_max_alarm:
+		return ltc2947_alarm_read(st, LTC2947_REG_STATIP,
+					  LTC2947_MAX_CURRENT_MASK, val);
+	case hwmon_curr_min_alarm:
+		return ltc2947_alarm_read(st, LTC2947_REG_STATIP,
+					  LTC2947_MIN_CURRENT_MASK, val);
+	case hwmon_curr_max:
+		ret = ltc2947_val_read(st, LTC2947_REG_CURRENT_THRE_H,
+				       LTC2947_PAGE1, 2, &__val);
+		break;
+	case hwmon_curr_min:
+		ret = ltc2947_val_read(st, LTC2947_REG_CURRENT_THRE_L,
+				       LTC2947_PAGE1, 2, &__val);
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	if (ret)
+		return ret;
+
+	*val = __val * lsb;
+
+	return 0;
+}
+
+static int ltc2947_read_in(struct device *dev, const u32 attr, long *val,
+			   const int channel)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+	int ret;
+	u8 lsb = 2; /* in mV */
+	s64 __val = 0;
+
+	if (channel < 0 || channel > LTC2947_VOLTAGE_DVCC_CHAN) {
+		dev_err(st->dev, "Invalid chan%d for voltage", channel);
+		return -EINVAL;
+	}
+
+	switch (attr) {
+	case hwmon_in_input:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN) {
+			ret = ltc2947_val_read(st, LTC2947_REG_DVCC,
+					       LTC2947_PAGE0, 2, &__val);
+			lsb = 145;
+		} else {
+			ret = ltc2947_val_read(st, LTC2947_REG_VOLTAGE,
+					       LTC2947_PAGE0, 2, &__val);
+		}
+		break;
+	case hwmon_in_highest:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN) {
+			ret = ltc2947_val_read(st, LTC2947_REG_DVCC_MAX,
+					       LTC2947_PAGE0, 2, &__val);
+			lsb = 145;
+		} else {
+			ret = ltc2947_val_read(st, LTC2947_REG_VOLTAGE_MAX,
+					       LTC2947_PAGE0, 2, &__val);
+		}
+		break;
+	case hwmon_in_lowest:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN) {
+			ret = ltc2947_val_read(st, LTC2947_REG_DVCC_MIN,
+					       LTC2947_PAGE0, 2, &__val);
+			lsb = 145;
+		} else {
+			ret = ltc2947_val_read(st, LTC2947_REG_VOLTAGE_MIN,
+					       LTC2947_PAGE0, 2, &__val);
+		}
+		break;
+	case hwmon_in_max_alarm:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN)
+			return ltc2947_alarm_read(st, LTC2947_REG_STATVDVCC,
+						  LTC2947_MAX_VOLTAGE_MASK,
+						  val);
+
+		return ltc2947_alarm_read(st, LTC2947_REG_STATVT,
+					  LTC2947_MAX_VOLTAGE_MASK, val);
+	case hwmon_in_min_alarm:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN)
+			return ltc2947_alarm_read(st, LTC2947_REG_STATVDVCC,
+						  LTC2947_MIN_VOLTAGE_MASK,
+						  val);
+
+		return ltc2947_alarm_read(st, LTC2947_REG_STATVT,
+					  LTC2947_MIN_VOLTAGE_MASK, val);
+	case hwmon_in_max:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN) {
+			ret = ltc2947_val_read(st, LTC2947_REG_DVCC_THRE_H,
+					       LTC2947_PAGE1, 2, &__val);
+			lsb = 145;
+		} else {
+			ret = ltc2947_val_read(st, LTC2947_REG_VOLTAGE_THRE_H,
+					       LTC2947_PAGE1, 2, &__val);
+		}
+		break;
+	case hwmon_in_min:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN) {
+			ret = ltc2947_val_read(st, LTC2947_REG_DVCC_THRE_L,
+					       LTC2947_PAGE1, 2, &__val);
+			lsb = 145;
+		} else {
+			ret = ltc2947_val_read(st, LTC2947_REG_VOLTAGE_THRE_L,
+					       LTC2947_PAGE1, 2, &__val);
+		}
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	if (ret)
+		return ret;
+
+	*val = __val * lsb;
+
+	return 0;
+}
+
+static int ltc2947_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_in:
+		return ltc2947_read_in(dev, attr, val, channel);
+	case hwmon_curr:
+		return ltc2947_read_curr(dev, attr, val);
+	case hwmon_power:
+		return ltc2947_read_power(dev, attr, val);
+	case hwmon_temp:
+		return ltc2947_read_temp(dev, attr, val, channel);
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int ltc2947_write_temp(struct device *dev, const u32 attr,
+			      long val, const int channel)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+
+	if (channel < 0 || channel > LTC2947_TEMP_FAN_CHAN) {
+		dev_err(st->dev, "Invalid chan%d for temperature", channel);
+		return -EINVAL;
+	}
+
+	switch (attr) {
+	case hwmon_temp_reset_history:
+		if (val != 1)
+			return -EINVAL;
+		return ltc2947_reset_history(st, LTC2947_REG_TEMP_MAX,
+					     LTC2947_REG_TEMP_MIN);
+	case hwmon_temp_max:
+		val = clamp_val(val, TEMP_MIN, TEMP_MAX);
+		if (channel == LTC2947_TEMP_FAN_CHAN) {
+			if (!st->gpio_out)
+				return -ENOTSUPP;
+
+			return ltc2947_val_write(st,
+					LTC2947_REG_TEMP_FAN_THRE_H,
+					LTC2947_PAGE1, 2,
+					DIV_ROUND_CLOSEST(val - 550, 204));
+		}
+
+		return ltc2947_val_write(st, LTC2947_REG_TEMP_THRE_H,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val - 550, 204));
+	case hwmon_temp_min:
+		val = clamp_val(val, TEMP_MIN, TEMP_MAX);
+		if (channel == LTC2947_TEMP_FAN_CHAN) {
+			if (!st->gpio_out)
+				return -ENOTSUPP;
+
+			return ltc2947_val_write(st,
+					LTC2947_REG_TEMP_FAN_THRE_L,
+					LTC2947_PAGE1, 2,
+					DIV_ROUND_CLOSEST(val - 550, 204));
+		}
+
+		return ltc2947_val_write(st, LTC2947_REG_TEMP_THRE_L,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val - 550, 204));
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int ltc2947_write_power(struct device *dev, const u32 attr,
+			       long val)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+
+	switch (attr) {
+	case hwmon_power_reset_history:
+		if (val != 1)
+			return -EINVAL;
+		return ltc2947_reset_history(st, LTC2947_REG_POWER_MAX,
+					     LTC2947_REG_POWER_MIN);
+	case hwmon_power_max:
+		val = clamp_val(val, POWER_MIN, POWER_MAX);
+		return ltc2947_val_write(st, LTC2947_REG_POWER_THRE_H,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val, 200000));
+	case hwmon_power_min:
+		val = clamp_val(val, POWER_MIN, POWER_MAX);
+		return ltc2947_val_write(st, LTC2947_REG_POWER_THRE_L,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val, 200000));
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int ltc2947_write_curr(struct device *dev, const u32 attr,
+			      long val)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+
+	switch (attr) {
+	case hwmon_curr_reset_history:
+		if (val != 1)
+			return -EINVAL;
+		return ltc2947_reset_history(st, LTC2947_REG_CURRENT_MAX,
+					     LTC2947_REG_CURRENT_MIN);
+	case hwmon_curr_max:
+		val = clamp_val(val, CURRENT_MIN, CURRENT_MAX);
+		return ltc2947_val_write(st, LTC2947_REG_CURRENT_THRE_H,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val, 12));
+	case hwmon_curr_min:
+		val = clamp_val(val, CURRENT_MIN, CURRENT_MAX);
+		return ltc2947_val_write(st, LTC2947_REG_CURRENT_THRE_L,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val, 12));
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int ltc2947_write_in(struct device *dev, const u32 attr, long val,
+			    const int channel)
+{
+	struct ltc2947_data *st = dev_get_drvdata(dev);
+
+	if (channel > LTC2947_VOLTAGE_DVCC_CHAN) {
+		dev_err(st->dev, "Invalid chan%d for voltage", channel);
+		return -EINVAL;
+	}
+
+	switch (attr) {
+	case hwmon_in_reset_history:
+		if (val != 1)
+			return -EINVAL;
+
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN)
+			return ltc2947_reset_history(st, LTC2947_REG_DVCC_MAX,
+						     LTC2947_REG_DVCC_MIN);
+
+		return ltc2947_reset_history(st, LTC2947_REG_VOLTAGE_MAX,
+					     LTC2947_REG_VOLTAGE_MIN);
+	case hwmon_in_max:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN) {
+			val = clamp_val(val, VDVCC_MIN, VDVCC_MAX);
+			return ltc2947_val_write(st, LTC2947_REG_DVCC_THRE_H,
+						 LTC2947_PAGE1, 2,
+						 DIV_ROUND_CLOSEST(val, 145));
+		}
+
+		val = clamp_val(val, VOLTAGE_MIN, VOLTAGE_MAX);
+		return ltc2947_val_write(st, LTC2947_REG_VOLTAGE_THRE_H,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val, 2));
+	case hwmon_in_min:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN) {
+			val = clamp_val(val, VDVCC_MIN, VDVCC_MAX);
+			return ltc2947_val_write(st, LTC2947_REG_DVCC_THRE_L,
+						 LTC2947_PAGE1, 2,
+						 DIV_ROUND_CLOSEST(val, 145));
+		}
+
+		val = clamp_val(val, VOLTAGE_MIN, VOLTAGE_MAX);
+		return ltc2947_val_write(st, LTC2947_REG_VOLTAGE_THRE_L,
+					 LTC2947_PAGE1, 2,
+					 DIV_ROUND_CLOSEST(val, 2));
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int ltc2947_write(struct device *dev,
+			 enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	switch (type) {
+	case hwmon_in:
+		return ltc2947_write_in(dev, attr, val, channel);
+	case hwmon_curr:
+		return ltc2947_write_curr(dev, attr, val);
+	case hwmon_power:
+		return ltc2947_write_power(dev, attr, val);
+	case hwmon_temp:
+		return ltc2947_write_temp(dev, attr, val, channel);
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int ltc2947_read_labels(struct device *dev,
+			       enum hwmon_sensor_types type,
+			       u32 attr, int channel, const char **str)
+{
+	switch (type) {
+	case hwmon_in:
+		if (channel == LTC2947_VOLTAGE_DVCC_CHAN)
+			*str = "DVCC";
+		else
+			*str = "VP-VM";
+		return 0;
+	case hwmon_curr:
+		*str = "IP-IM";
+		return 0;
+	case hwmon_temp:
+		if (channel == LTC2947_TEMP_FAN_CHAN)
+			*str = "TEMPFAN";
+		else
+			*str = "Ambient";
+		return 0;
+	case hwmon_power:
+		*str = "Power";
+		return 0;
+	default:
+		return -ENOTSUPP;
+	}
+}
+
+static int ltc2947_in_is_visible(const u32 attr)
+{
+	switch (attr) {
+	case hwmon_in_input:
+	case hwmon_in_highest:
+	case hwmon_in_lowest:
+	case hwmon_in_max_alarm:
+	case hwmon_in_min_alarm:
+	case hwmon_in_label:
+		return 0444;
+	case hwmon_in_reset_history:
+		return 0200;
+	case hwmon_in_max:
+	case hwmon_in_min:
+		return 0644;
+	default:
+		return 0;
+	}
+}
+
+static int ltc2947_curr_is_visible(const u32 attr)
+{
+	switch (attr) {
+	case hwmon_curr_input:
+	case hwmon_curr_highest:
+	case hwmon_curr_lowest:
+	case hwmon_curr_max_alarm:
+	case hwmon_curr_min_alarm:
+	case hwmon_curr_label:
+		return 0444;
+	case hwmon_curr_reset_history:
+		return 0200;
+	case hwmon_curr_max:
+	case hwmon_curr_min:
+		return 0644;
+	default:
+		return 0;
+	}
+}
+
+static int ltc2947_power_is_visible(const u32 attr)
+{
+	switch (attr) {
+	case hwmon_power_input:
+	case hwmon_power_input_highest:
+	case hwmon_power_input_lowest:
+	case hwmon_power_label:
+	case hwmon_power_max_alarm:
+	case hwmon_power_min_alarm: