drivers/hwmon/ltc2945.c - kernel/lockdown - Git at Google

 /*
  * Driver for Linear Technology LTC2945 I2C Power Monitor
  *
  * Copyright (c) 2014 Guenter Roeck
  *
  * 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/kernel.h>
 #include <linux/module.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/jiffies.h>
 #include <linux/regmap.h>

 /* chip registers */
 #define LTC2945_CONTROL			0x00
 #define LTC2945_ALERT			0x01
 #define LTC2945_STATUS			0x02
 #define LTC2945_FAULT			0x03
 #define LTC2945_POWER_H			0x05
 #define LTC2945_MAX_POWER_H		0x08
 #define LTC2945_MIN_POWER_H		0x0b
 #define LTC2945_MAX_POWER_THRES_H	0x0e
 #define LTC2945_MIN_POWER_THRES_H	0x11
 #define LTC2945_SENSE_H			0x14
 #define LTC2945_MAX_SENSE_H		0x16
 #define LTC2945_MIN_SENSE_H		0x18
 #define LTC2945_MAX_SENSE_THRES_H	0x1a
 #define LTC2945_MIN_SENSE_THRES_H	0x1c
 #define LTC2945_VIN_H			0x1e
 #define LTC2945_MAX_VIN_H		0x20
 #define LTC2945_MIN_VIN_H		0x22
 #define LTC2945_MAX_VIN_THRES_H		0x24
 #define LTC2945_MIN_VIN_THRES_H		0x26
 #define LTC2945_ADIN_H			0x28
 #define LTC2945_MAX_ADIN_H		0x2a
 #define LTC2945_MIN_ADIN_H		0x2c
 #define LTC2945_MAX_ADIN_THRES_H	0x2e
 #define LTC2945_MIN_ADIN_THRES_H	0x30
 #define LTC2945_MIN_ADIN_THRES_L	0x31

 /* Fault register bits */

 #define FAULT_ADIN_UV		(1 << 0)
 #define FAULT_ADIN_OV		(1 << 1)
 #define FAULT_VIN_UV		(1 << 2)
 #define FAULT_VIN_OV		(1 << 3)
 #define FAULT_SENSE_UV		(1 << 4)
 #define FAULT_SENSE_OV		(1 << 5)
 #define FAULT_POWER_UV		(1 << 6)
 #define FAULT_POWER_OV		(1 << 7)

 /* Control register bits */

 #define CONTROL_MULT_SELECT	(1 << 0)
 #define CONTROL_TEST_MODE	(1 << 4)

 static inline bool is_power_reg(u8 reg)
 {
 	return reg < LTC2945_SENSE_H;
 }

 /* Return the value from the given register in uW, mV, or mA */
 static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	unsigned int control;
 	u8 buf[3];
 	long long val;
 	int ret;

 	ret = regmap_bulk_read(regmap, reg, buf,
 			       is_power_reg(reg) ? 3 : 2);
 	if (ret < 0)
 		return ret;

 	if (is_power_reg(reg)) {
 		/* power */
 		val = (buf[0] << 16) + (buf[1] << 8) + buf[2];
 	} else {
 		/* current, voltage */
 		val = (buf[0] << 4) + (buf[1] >> 4);
 	}

 	switch (reg) {
 	case LTC2945_POWER_H:
 	case LTC2945_MAX_POWER_H:
 	case LTC2945_MIN_POWER_H:
 	case LTC2945_MAX_POWER_THRES_H:
 	case LTC2945_MIN_POWER_THRES_H:
 		/*
 		 * Convert to uW by assuming current is measured with
 		 * an 1mOhm sense resistor, similar to current
 		 * measurements.
 		 * Control register bit 0 selects if voltage at SENSE+/VDD
 		 * or voltage at ADIN is used to measure power.
 		 */
 		ret = regmap_read(regmap, LTC2945_CONTROL, &control);
 		if (ret < 0)
 			return ret;
 		if (control & CONTROL_MULT_SELECT) {
 			/* 25 mV * 25 uV = 0.625 uV resolution. */
 			val *= 625LL;
 		} else {
 			/* 0.5 mV * 25 uV = 0.0125 uV resolution. */
 			val = (val * 25LL) >> 1;
 		}
 		break;
 	case LTC2945_VIN_H:
 	case LTC2945_MAX_VIN_H:
 	case LTC2945_MIN_VIN_H:
 	case LTC2945_MAX_VIN_THRES_H:
 	case LTC2945_MIN_VIN_THRES_H:
 		/* 25 mV resolution. Convert to mV. */
 		val *= 25;
 		break;
 	case LTC2945_ADIN_H:
 	case LTC2945_MAX_ADIN_H:
 	case LTC2945_MIN_ADIN_THRES_H:
 	case LTC2945_MAX_ADIN_THRES_H:
 	case LTC2945_MIN_ADIN_H:
 		/* 0.5mV resolution. Convert to mV. */
 		val = val >> 1;
 		break;
 	case LTC2945_SENSE_H:
 	case LTC2945_MAX_SENSE_H:
 	case LTC2945_MIN_SENSE_H:
 	case LTC2945_MAX_SENSE_THRES_H:
 	case LTC2945_MIN_SENSE_THRES_H:
 		/*
 		 * 25 uV resolution. Convert to current as measured with
 		 * an 1 mOhm sense resistor, in mA. If a different sense
 		 * resistor is installed, calculate the actual current by
 		 * dividing the reported current by the sense resistor value
 		 * in mOhm.
 		 */
 		val *= 25;
 		break;
 	default:
 		return -EINVAL;
 	}
 	return val;
 }

 static int ltc2945_val_to_reg(struct device *dev, u8 reg,
 			      unsigned long val)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	unsigned int control;
 	int ret;

 	switch (reg) {
 	case LTC2945_POWER_H:
 	case LTC2945_MAX_POWER_H:
 	case LTC2945_MIN_POWER_H:
 	case LTC2945_MAX_POWER_THRES_H:
 	case LTC2945_MIN_POWER_THRES_H:
 		/*
 		 * Convert to register value by assuming current is measured
 		 * with an 1mOhm sense resistor, similar to current
 		 * measurements.
 		 * Control register bit 0 selects if voltage at SENSE+/VDD
 		 * or voltage at ADIN is used to measure power, which in turn
 		 * determines register calculations.
 		 */
 		ret = regmap_read(regmap, LTC2945_CONTROL, &control);
 		if (ret < 0)
 			return ret;
 		if (control & CONTROL_MULT_SELECT) {
 			/* 25 mV * 25 uV = 0.625 uV resolution. */
 			val = DIV_ROUND_CLOSEST(val, 625);
 		} else {
 			/*
 			 * 0.5 mV * 25 uV = 0.0125 uV resolution.
 			 * Divide first to avoid overflow;
 			 * accept loss of accuracy.
 			 */
 			val = DIV_ROUND_CLOSEST(val, 25) * 2;
 		}
 		break;
 	case LTC2945_VIN_H:
 	case LTC2945_MAX_VIN_H:
 	case LTC2945_MIN_VIN_H:
 	case LTC2945_MAX_VIN_THRES_H:
 	case LTC2945_MIN_VIN_THRES_H:
 		/* 25 mV resolution. */
 		val /= 25;
 		break;
 	case LTC2945_ADIN_H:
 	case LTC2945_MAX_ADIN_H:
 	case LTC2945_MIN_ADIN_THRES_H:
 	case LTC2945_MAX_ADIN_THRES_H:
 	case LTC2945_MIN_ADIN_H:
 		/* 0.5mV resolution. */
 		val *= 2;
 		break;
 	case LTC2945_SENSE_H:
 	case LTC2945_MAX_SENSE_H:
 	case LTC2945_MIN_SENSE_H:
 	case LTC2945_MAX_SENSE_THRES_H:
 	case LTC2945_MIN_SENSE_THRES_H:
 		/*
 		 * 25 uV resolution. Convert to current as measured with
 		 * an 1 mOhm sense resistor, in mA. If a different sense
 		 * resistor is installed, calculate the actual current by
 		 * dividing the reported current by the sense resistor value
 		 * in mOhm.
 		 */
 		val = DIV_ROUND_CLOSEST(val, 25);
 		break;
 	default:
 		return -EINVAL;
 	}
 	return val;
 }

 static ssize_t ltc2945_show_value(struct device *dev,
 				  struct device_attribute *da, char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	long long value;

 	value = ltc2945_reg_to_val(dev, attr->index);
 	if (value < 0)
 		return value;
 	return snprintf(buf, PAGE_SIZE, "%lld\n", value);
 }

 static ssize_t ltc2945_set_value(struct device *dev,
 				     struct device_attribute *da,
 				     const char *buf, size_t count)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct regmap *regmap = dev_get_drvdata(dev);
 	u8 reg = attr->index;
 	unsigned long val;
 	u8 regbuf[3];
 	int num_regs;
 	int regval;
 	int ret;

 	ret = kstrtoul(buf, 10, &val);
 	if (ret)
 		return ret;

 	/* convert to register value, then clamp and write result */
 	regval = ltc2945_val_to_reg(dev, reg, val);
 	if (is_power_reg(reg)) {
 		regval = clamp_val(regval, 0, 0xffffff);
 		regbuf[0] = regval >> 16;
 		regbuf[1] = (regval >> 8) & 0xff;
 		regbuf[2] = regval;
 		num_regs = 3;
 	} else {
 		regval = clamp_val(regval, 0, 0xfff) << 4;
 		regbuf[0] = regval >> 8;
 		regbuf[1] = regval & 0xff;
 		num_regs = 2;
 	}
 	ret = regmap_bulk_write(regmap, reg, regbuf, num_regs);
 	return ret < 0 ? ret : count;
 }

 static ssize_t ltc2945_reset_history(struct device *dev,
 				     struct device_attribute *da,
 				     const char *buf, size_t count)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct regmap *regmap = dev_get_drvdata(dev);
 	u8 reg = attr->index;
 	int num_regs = is_power_reg(reg) ? 3 : 2;
 	u8 buf_min[3] = { 0xff, 0xff, 0xff };
 	u8 buf_max[3] = { 0, 0, 0 };
 	unsigned long val;
 	int ret;

 	ret = kstrtoul(buf, 10, &val);
 	if (ret)
 		return ret;
 	if (val != 1)
 		return -EINVAL;

 	ret = regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE,
 				 CONTROL_TEST_MODE);

 	/* Reset minimum */
 	ret = regmap_bulk_write(regmap, reg, buf_min, num_regs);
 	if (ret)
 		return ret;

 	switch (reg) {
 	case LTC2945_MIN_POWER_H:
 		reg = LTC2945_MAX_POWER_H;
 		break;
 	case LTC2945_MIN_SENSE_H:
 		reg = LTC2945_MAX_SENSE_H;
 		break;
 	case LTC2945_MIN_VIN_H:
 		reg = LTC2945_MAX_VIN_H;
 		break;
 	case LTC2945_MIN_ADIN_H:
 		reg = LTC2945_MAX_ADIN_H;
 		break;
 	default:
 		WARN_ONCE(1, "Bad register: 0x%x\n", reg);
 		return -EINVAL;
 	}
 	/* Reset maximum */
 	ret = regmap_bulk_write(regmap, reg, buf_max, num_regs);

 	/* Try resetting test mode even if there was an error */
 	regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE, 0);

 	return ret ? : count;
 }

 static ssize_t ltc2945_show_bool(struct device *dev,
 				 struct device_attribute *da, char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct regmap *regmap = dev_get_drvdata(dev);
 	unsigned int fault;
 	int ret;

 	ret = regmap_read(regmap, LTC2945_FAULT, &fault);
 	if (ret < 0)
 		return ret;

 	fault &= attr->index;
 	if (fault)		/* Clear reported faults in chip register */
 		regmap_update_bits(regmap, LTC2945_FAULT, attr->index, 0);

 	return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
 }

 /* Input voltages */

 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_VIN_H);
 static SENSOR_DEVICE_ATTR(in1_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MIN_VIN_THRES_H);
 static SENSOR_DEVICE_ATTR(in1_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MAX_VIN_THRES_H);
 static SENSOR_DEVICE_ATTR(in1_lowest, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_MIN_VIN_H);
 static SENSOR_DEVICE_ATTR(in1_highest, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_MAX_VIN_H);
 static SENSOR_DEVICE_ATTR(in1_reset_history, S_IWUSR, NULL,
 			  ltc2945_reset_history, LTC2945_MIN_VIN_H);

 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_ADIN_H);
 static SENSOR_DEVICE_ATTR(in2_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MIN_ADIN_THRES_H);
 static SENSOR_DEVICE_ATTR(in2_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MAX_ADIN_THRES_H);
 static SENSOR_DEVICE_ATTR(in2_lowest, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_MIN_ADIN_H);
 static SENSOR_DEVICE_ATTR(in2_highest, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_MAX_ADIN_H);
 static SENSOR_DEVICE_ATTR(in2_reset_history, S_IWUSR, NULL,
 			  ltc2945_reset_history, LTC2945_MIN_ADIN_H);

 /* Voltage alarms */

 static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_VIN_UV);
 static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_VIN_OV);
 static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_ADIN_UV);
 static SENSOR_DEVICE_ATTR(in2_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_ADIN_OV);

 /* Currents (via sense resistor) */

 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_SENSE_H);
 static SENSOR_DEVICE_ATTR(curr1_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MIN_SENSE_THRES_H);
 static SENSOR_DEVICE_ATTR(curr1_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MAX_SENSE_THRES_H);
 static SENSOR_DEVICE_ATTR(curr1_lowest, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_MIN_SENSE_H);
 static SENSOR_DEVICE_ATTR(curr1_highest, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_MAX_SENSE_H);
 static SENSOR_DEVICE_ATTR(curr1_reset_history, S_IWUSR, NULL,
 			  ltc2945_reset_history, LTC2945_MIN_SENSE_H);

 /* Current alarms */

 static SENSOR_DEVICE_ATTR(curr1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_SENSE_UV);
 static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_SENSE_OV);

 /* Power */

 static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ltc2945_show_value, NULL,
 			  LTC2945_POWER_H);
 static SENSOR_DEVICE_ATTR(power1_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MIN_POWER_THRES_H);
 static SENSOR_DEVICE_ATTR(power1_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
 			  ltc2945_set_value, LTC2945_MAX_POWER_THRES_H);
 static SENSOR_DEVICE_ATTR(power1_input_lowest, S_IRUGO, ltc2945_show_value,
 			  NULL, LTC2945_MIN_POWER_H);
 static SENSOR_DEVICE_ATTR(power1_input_highest, S_IRUGO, ltc2945_show_value,
 			  NULL, LTC2945_MAX_POWER_H);
 static SENSOR_DEVICE_ATTR(power1_reset_history, S_IWUSR, NULL,
 			  ltc2945_reset_history, LTC2945_MIN_POWER_H);

 /* Power alarms */

 static SENSOR_DEVICE_ATTR(power1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_POWER_UV);
 static SENSOR_DEVICE_ATTR(power1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
 			  FAULT_POWER_OV);

 static struct attribute *ltc2945_attrs[] = {
 	&sensor_dev_attr_in1_input.dev_attr.attr,
 	&sensor_dev_attr_in1_min.dev_attr.attr,
 	&sensor_dev_attr_in1_max.dev_attr.attr,
 	&sensor_dev_attr_in1_lowest.dev_attr.attr,
 	&sensor_dev_attr_in1_highest.dev_attr.attr,
 	&sensor_dev_attr_in1_reset_history.dev_attr.attr,
 	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,

 	&sensor_dev_attr_in2_input.dev_attr.attr,
 	&sensor_dev_attr_in2_min.dev_attr.attr,
 	&sensor_dev_attr_in2_max.dev_attr.attr,
 	&sensor_dev_attr_in2_lowest.dev_attr.attr,
 	&sensor_dev_attr_in2_highest.dev_attr.attr,
 	&sensor_dev_attr_in2_reset_history.dev_attr.attr,
 	&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_in2_max_alarm.dev_attr.attr,

 	&sensor_dev_attr_curr1_input.dev_attr.attr,
 	&sensor_dev_attr_curr1_min.dev_attr.attr,
 	&sensor_dev_attr_curr1_max.dev_attr.attr,
 	&sensor_dev_attr_curr1_lowest.dev_attr.attr,
 	&sensor_dev_attr_curr1_highest.dev_attr.attr,
 	&sensor_dev_attr_curr1_reset_history.dev_attr.attr,
 	&sensor_dev_attr_curr1_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,

 	&sensor_dev_attr_power1_input.dev_attr.attr,
 	&sensor_dev_attr_power1_min.dev_attr.attr,
 	&sensor_dev_attr_power1_max.dev_attr.attr,
 	&sensor_dev_attr_power1_input_lowest.dev_attr.attr,
 	&sensor_dev_attr_power1_input_highest.dev_attr.attr,
 	&sensor_dev_attr_power1_reset_history.dev_attr.attr,
 	&sensor_dev_attr_power1_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_power1_max_alarm.dev_attr.attr,

 	NULL,
 };
 ATTRIBUTE_GROUPS(ltc2945);

 static const struct regmap_config ltc2945_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.max_register = LTC2945_MIN_ADIN_THRES_L,
 };

 static int ltc2945_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
 	struct regmap *regmap;

 	regmap = devm_regmap_init_i2c(client, &ltc2945_regmap_config);
 	if (IS_ERR(regmap)) {
 		dev_err(dev, "failed to allocate register map\n");
 		return PTR_ERR(regmap);
 	}

 	/* Clear faults */
 	regmap_write(regmap, LTC2945_FAULT, 0x00);

 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   regmap,
 							   ltc2945_groups);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static const struct i2c_device_id ltc2945_id[] = {
 	{"ltc2945", 0},
 	{ }
 };

 MODULE_DEVICE_TABLE(i2c, ltc2945_id);

 static struct i2c_driver ltc2945_driver = {
 	.driver = {
 		   .name = "ltc2945",
 		   },
 	.probe = ltc2945_probe,
 	.id_table = ltc2945_id,
 };

 module_i2c_driver(ltc2945_driver);

 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
 MODULE_DESCRIPTION("LTC2945 driver");
 MODULE_LICENSE("GPL");
	/*
	* Driver for Linear Technology LTC2945 I2C Power Monitor
	*
	* Copyright (c) 2014 Guenter Roeck
	*
	* 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/kernel.h>
	#include <linux/module.h>
	#include <linux/err.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>
	#include <linux/jiffies.h>
	#include <linux/regmap.h>

	/* chip registers */
	#define LTC2945_CONTROL 0x00
	#define LTC2945_ALERT 0x01
	#define LTC2945_STATUS 0x02
	#define LTC2945_FAULT 0x03
	#define LTC2945_POWER_H 0x05
	#define LTC2945_MAX_POWER_H 0x08
	#define LTC2945_MIN_POWER_H 0x0b
	#define LTC2945_MAX_POWER_THRES_H 0x0e
	#define LTC2945_MIN_POWER_THRES_H 0x11
	#define LTC2945_SENSE_H 0x14
	#define LTC2945_MAX_SENSE_H 0x16
	#define LTC2945_MIN_SENSE_H 0x18
	#define LTC2945_MAX_SENSE_THRES_H 0x1a
	#define LTC2945_MIN_SENSE_THRES_H 0x1c
	#define LTC2945_VIN_H 0x1e
	#define LTC2945_MAX_VIN_H 0x20
	#define LTC2945_MIN_VIN_H 0x22
	#define LTC2945_MAX_VIN_THRES_H 0x24
	#define LTC2945_MIN_VIN_THRES_H 0x26
	#define LTC2945_ADIN_H 0x28
	#define LTC2945_MAX_ADIN_H 0x2a
	#define LTC2945_MIN_ADIN_H 0x2c
	#define LTC2945_MAX_ADIN_THRES_H 0x2e
	#define LTC2945_MIN_ADIN_THRES_H 0x30
	#define LTC2945_MIN_ADIN_THRES_L 0x31

	/* Fault register bits */

	#define FAULT_ADIN_UV (1 << 0)
	#define FAULT_ADIN_OV (1 << 1)
	#define FAULT_VIN_UV (1 << 2)
	#define FAULT_VIN_OV (1 << 3)
	#define FAULT_SENSE_UV (1 << 4)
	#define FAULT_SENSE_OV (1 << 5)
	#define FAULT_POWER_UV (1 << 6)
	#define FAULT_POWER_OV (1 << 7)

	/* Control register bits */

	#define CONTROL_MULT_SELECT (1 << 0)
	#define CONTROL_TEST_MODE (1 << 4)

	static inline bool is_power_reg(u8 reg)
	{
	return reg < LTC2945_SENSE_H;
	}

	/* Return the value from the given register in uW, mV, or mA */
	static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	unsigned int control;
	u8 buf[3];
	long long val;
	int ret;

	ret = regmap_bulk_read(regmap, reg, buf,
	is_power_reg(reg) ? 3 : 2);
	if (ret < 0)
	return ret;

	if (is_power_reg(reg)) {
	/* power */
	val = (buf[0] << 16) + (buf[1] << 8) + buf[2];
	} else {
	/* current, voltage */
	val = (buf[0] << 4) + (buf[1] >> 4);
	}

	switch (reg) {
	case LTC2945_POWER_H:
	case LTC2945_MAX_POWER_H:
	case LTC2945_MIN_POWER_H:
	case LTC2945_MAX_POWER_THRES_H:
	case LTC2945_MIN_POWER_THRES_H:
	/*
	* Convert to uW by assuming current is measured with
	* an 1mOhm sense resistor, similar to current
	* measurements.
	* Control register bit 0 selects if voltage at SENSE+/VDD
	* or voltage at ADIN is used to measure power.
	*/
	ret = regmap_read(regmap, LTC2945_CONTROL, &control);
	if (ret < 0)
	return ret;
	if (control & CONTROL_MULT_SELECT) {
	/* 25 mV * 25 uV = 0.625 uV resolution. */
	val *= 625LL;
	} else {
	/* 0.5 mV * 25 uV = 0.0125 uV resolution. */
	val = (val * 25LL) >> 1;
	}
	break;
	case LTC2945_VIN_H:
	case LTC2945_MAX_VIN_H:
	case LTC2945_MIN_VIN_H:
	case LTC2945_MAX_VIN_THRES_H:
	case LTC2945_MIN_VIN_THRES_H:
	/* 25 mV resolution. Convert to mV. */
	val *= 25;
	break;
	case LTC2945_ADIN_H:
	case LTC2945_MAX_ADIN_H:
	case LTC2945_MIN_ADIN_THRES_H:
	case LTC2945_MAX_ADIN_THRES_H:
	case LTC2945_MIN_ADIN_H:
	/* 0.5mV resolution. Convert to mV. */
	val = val >> 1;
	break;
	case LTC2945_SENSE_H:
	case LTC2945_MAX_SENSE_H:
	case LTC2945_MIN_SENSE_H:
	case LTC2945_MAX_SENSE_THRES_H:
	case LTC2945_MIN_SENSE_THRES_H:
	/*
	* 25 uV resolution. Convert to current as measured with
	* an 1 mOhm sense resistor, in mA. If a different sense
	* resistor is installed, calculate the actual current by
	* dividing the reported current by the sense resistor value
	* in mOhm.
	*/
	val *= 25;
	break;
	default:
	return -EINVAL;
	}
	return val;
	}

	static int ltc2945_val_to_reg(struct device *dev, u8 reg,
	unsigned long val)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	unsigned int control;
	int ret;

	switch (reg) {
	case LTC2945_POWER_H:
	case LTC2945_MAX_POWER_H:
	case LTC2945_MIN_POWER_H:
	case LTC2945_MAX_POWER_THRES_H:
	case LTC2945_MIN_POWER_THRES_H:
	/*
	* Convert to register value by assuming current is measured
	* with an 1mOhm sense resistor, similar to current
	* measurements.
	* Control register bit 0 selects if voltage at SENSE+/VDD
	* or voltage at ADIN is used to measure power, which in turn
	* determines register calculations.
	*/
	ret = regmap_read(regmap, LTC2945_CONTROL, &control);
	if (ret < 0)
	return ret;
	if (control & CONTROL_MULT_SELECT) {
	/* 25 mV * 25 uV = 0.625 uV resolution. */
	val = DIV_ROUND_CLOSEST(val, 625);
	} else {
	/*
	* 0.5 mV * 25 uV = 0.0125 uV resolution.
	* Divide first to avoid overflow;
	* accept loss of accuracy.
	*/
	val = DIV_ROUND_CLOSEST(val, 25) * 2;
	}
	break;
	case LTC2945_VIN_H:
	case LTC2945_MAX_VIN_H:
	case LTC2945_MIN_VIN_H:
	case LTC2945_MAX_VIN_THRES_H:
	case LTC2945_MIN_VIN_THRES_H:
	/* 25 mV resolution. */
	val /= 25;
	break;
	case LTC2945_ADIN_H:
	case LTC2945_MAX_ADIN_H:
	case LTC2945_MIN_ADIN_THRES_H:
	case LTC2945_MAX_ADIN_THRES_H:
	case LTC2945_MIN_ADIN_H:
	/* 0.5mV resolution. */
	val *= 2;
	break;
	case LTC2945_SENSE_H:
	case LTC2945_MAX_SENSE_H:
	case LTC2945_MIN_SENSE_H:
	case LTC2945_MAX_SENSE_THRES_H:
	case LTC2945_MIN_SENSE_THRES_H:
	/*
	* 25 uV resolution. Convert to current as measured with
	* an 1 mOhm sense resistor, in mA. If a different sense
	* resistor is installed, calculate the actual current by
	* dividing the reported current by the sense resistor value
	* in mOhm.
	*/
	val = DIV_ROUND_CLOSEST(val, 25);
	break;
	default:
	return -EINVAL;
	}
	return val;
	}

	static ssize_t ltc2945_show_value(struct device *dev,
	struct device_attribute da, char buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	long long value;

	value = ltc2945_reg_to_val(dev, attr->index);
	if (value < 0)
	return value;
	return snprintf(buf, PAGE_SIZE, "%lld\n", value);
	}

	static ssize_t ltc2945_set_value(struct device *dev,
	struct device_attribute *da,
	const char *buf, size_t count)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct regmap *regmap = dev_get_drvdata(dev);
	u8 reg = attr->index;
	unsigned long val;
	u8 regbuf[3];
	int num_regs;
	int regval;
	int ret;

	ret = kstrtoul(buf, 10, &val);
	if (ret)
	return ret;

	/* convert to register value, then clamp and write result */
	regval = ltc2945_val_to_reg(dev, reg, val);
	if (is_power_reg(reg)) {
	regval = clamp_val(regval, 0, 0xffffff);
	regbuf[0] = regval >> 16;
	regbuf[1] = (regval >> 8) & 0xff;
	regbuf[2] = regval;
	num_regs = 3;
	} else {
	regval = clamp_val(regval, 0, 0xfff) << 4;
	regbuf[0] = regval >> 8;
	regbuf[1] = regval & 0xff;
	num_regs = 2;
	}
	ret = regmap_bulk_write(regmap, reg, regbuf, num_regs);
	return ret < 0 ? ret : count;
	}

	static ssize_t ltc2945_reset_history(struct device *dev,
	struct device_attribute *da,
	const char *buf, size_t count)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct regmap *regmap = dev_get_drvdata(dev);
	u8 reg = attr->index;
	int num_regs = is_power_reg(reg) ? 3 : 2;
	u8 buf_min[3] = { 0xff, 0xff, 0xff };
	u8 buf_max[3] = { 0, 0, 0 };
	unsigned long val;
	int ret;

	ret = kstrtoul(buf, 10, &val);
	if (ret)
	return ret;
	if (val != 1)
	return -EINVAL;

	ret = regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE,
	CONTROL_TEST_MODE);

	/* Reset minimum */
	ret = regmap_bulk_write(regmap, reg, buf_min, num_regs);
	if (ret)
	return ret;

	switch (reg) {
	case LTC2945_MIN_POWER_H:
	reg = LTC2945_MAX_POWER_H;
	break;
	case LTC2945_MIN_SENSE_H:
	reg = LTC2945_MAX_SENSE_H;
	break;
	case LTC2945_MIN_VIN_H:
	reg = LTC2945_MAX_VIN_H;
	break;
	case LTC2945_MIN_ADIN_H:
	reg = LTC2945_MAX_ADIN_H;
	break;
	default:
	WARN_ONCE(1, "Bad register: 0x%x\n", reg);
	return -EINVAL;
	}
	/* Reset maximum */
	ret = regmap_bulk_write(regmap, reg, buf_max, num_regs);

	/* Try resetting test mode even if there was an error */
	regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE, 0);

	return ret ? : count;
	}

	static ssize_t ltc2945_show_bool(struct device *dev,
	struct device_attribute da, char buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct regmap *regmap = dev_get_drvdata(dev);
	unsigned int fault;
	int ret;

	ret = regmap_read(regmap, LTC2945_FAULT, &fault);
	if (ret < 0)
	return ret;

	fault &= attr->index;
	if (fault) /* Clear reported faults in chip register */
	regmap_update_bits(regmap, LTC2945_FAULT, attr->index, 0);

	return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
	}

	/* Input voltages */

	static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_VIN_H);
	static SENSOR_DEVICE_ATTR(in1_min, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MIN_VIN_THRES_H);
	static SENSOR_DEVICE_ATTR(in1_max, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MAX_VIN_THRES_H);
	static SENSOR_DEVICE_ATTR(in1_lowest, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_MIN_VIN_H);
	static SENSOR_DEVICE_ATTR(in1_highest, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_MAX_VIN_H);
	static SENSOR_DEVICE_ATTR(in1_reset_history, S_IWUSR, NULL,
	ltc2945_reset_history, LTC2945_MIN_VIN_H);

	static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_ADIN_H);
	static SENSOR_DEVICE_ATTR(in2_min, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MIN_ADIN_THRES_H);
	static SENSOR_DEVICE_ATTR(in2_max, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MAX_ADIN_THRES_H);
	static SENSOR_DEVICE_ATTR(in2_lowest, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_MIN_ADIN_H);
	static SENSOR_DEVICE_ATTR(in2_highest, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_MAX_ADIN_H);
	static SENSOR_DEVICE_ATTR(in2_reset_history, S_IWUSR, NULL,
	ltc2945_reset_history, LTC2945_MIN_ADIN_H);

	/* Voltage alarms */

	static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_VIN_UV);
	static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_VIN_OV);
	static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_ADIN_UV);
	static SENSOR_DEVICE_ATTR(in2_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_ADIN_OV);

	/* Currents (via sense resistor) */

	static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_SENSE_H);
	static SENSOR_DEVICE_ATTR(curr1_min, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MIN_SENSE_THRES_H);
	static SENSOR_DEVICE_ATTR(curr1_max, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MAX_SENSE_THRES_H);
	static SENSOR_DEVICE_ATTR(curr1_lowest, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_MIN_SENSE_H);
	static SENSOR_DEVICE_ATTR(curr1_highest, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_MAX_SENSE_H);
	static SENSOR_DEVICE_ATTR(curr1_reset_history, S_IWUSR, NULL,
	ltc2945_reset_history, LTC2945_MIN_SENSE_H);

	/* Current alarms */

	static SENSOR_DEVICE_ATTR(curr1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_SENSE_UV);
	static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_SENSE_OV);

	/* Power */

	static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ltc2945_show_value, NULL,
	LTC2945_POWER_H);
	static SENSOR_DEVICE_ATTR(power1_min, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MIN_POWER_THRES_H);
	static SENSOR_DEVICE_ATTR(power1_max, S_IRUGO \| S_IWUSR, ltc2945_show_value,
	ltc2945_set_value, LTC2945_MAX_POWER_THRES_H);
	static SENSOR_DEVICE_ATTR(power1_input_lowest, S_IRUGO, ltc2945_show_value,
	NULL, LTC2945_MIN_POWER_H);
	static SENSOR_DEVICE_ATTR(power1_input_highest, S_IRUGO, ltc2945_show_value,
	NULL, LTC2945_MAX_POWER_H);
	static SENSOR_DEVICE_ATTR(power1_reset_history, S_IWUSR, NULL,
	ltc2945_reset_history, LTC2945_MIN_POWER_H);

	/* Power alarms */

	static SENSOR_DEVICE_ATTR(power1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_POWER_UV);
	static SENSOR_DEVICE_ATTR(power1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
	FAULT_POWER_OV);

	static struct attribute *ltc2945_attrs[] = {
	&sensor_dev_attr_in1_input.dev_attr.attr,
	&sensor_dev_attr_in1_min.dev_attr.attr,
	&sensor_dev_attr_in1_max.dev_attr.attr,
	&sensor_dev_attr_in1_lowest.dev_attr.attr,
	&sensor_dev_attr_in1_highest.dev_attr.attr,
	&sensor_dev_attr_in1_reset_history.dev_attr.attr,
	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,

	&sensor_dev_attr_in2_input.dev_attr.attr,
	&sensor_dev_attr_in2_min.dev_attr.attr,
	&sensor_dev_attr_in2_max.dev_attr.attr,
	&sensor_dev_attr_in2_lowest.dev_attr.attr,
	&sensor_dev_attr_in2_highest.dev_attr.attr,
	&sensor_dev_attr_in2_reset_history.dev_attr.attr,
	&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
	&sensor_dev_attr_in2_max_alarm.dev_attr.attr,

	&sensor_dev_attr_curr1_input.dev_attr.attr,
	&sensor_dev_attr_curr1_min.dev_attr.attr,
	&sensor_dev_attr_curr1_max.dev_attr.attr,
	&sensor_dev_attr_curr1_lowest.dev_attr.attr,
	&sensor_dev_attr_curr1_highest.dev_attr.attr,
	&sensor_dev_attr_curr1_reset_history.dev_attr.attr,
	&sensor_dev_attr_curr1_min_alarm.dev_attr.attr,
	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,

	&sensor_dev_attr_power1_input.dev_attr.attr,
	&sensor_dev_attr_power1_min.dev_attr.attr,
	&sensor_dev_attr_power1_max.dev_attr.attr,
	&sensor_dev_attr_power1_input_lowest.dev_attr.attr,
	&sensor_dev_attr_power1_input_highest.dev_attr.attr,
	&sensor_dev_attr_power1_reset_history.dev_attr.attr,
	&sensor_dev_attr_power1_min_alarm.dev_attr.attr,
	&sensor_dev_attr_power1_max_alarm.dev_attr.attr,

	NULL,
	};
	ATTRIBUTE_GROUPS(ltc2945);

	static const struct regmap_config ltc2945_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = LTC2945_MIN_ADIN_THRES_L,
	};

	static int ltc2945_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct regmap *regmap;

	regmap = devm_regmap_init_i2c(client, &ltc2945_regmap_config);
	if (IS_ERR(regmap)) {
	dev_err(dev, "failed to allocate register map\n");
	return PTR_ERR(regmap);
	}

	/* Clear faults */
	regmap_write(regmap, LTC2945_FAULT, 0x00);

	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
	regmap,
	ltc2945_groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static const struct i2c_device_id ltc2945_id[] = {
	{"ltc2945", 0},
	{ }
	};

	MODULE_DEVICE_TABLE(i2c, ltc2945_id);

	static struct i2c_driver ltc2945_driver = {
	.driver = {
	.name = "ltc2945",
	},
	.probe = ltc2945_probe,
	.id_table = ltc2945_id,
	};

	module_i2c_driver(ltc2945_driver);

	MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
	MODULE_DESCRIPTION("LTC2945 driver");
	MODULE_LICENSE("GPL");