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/*
* Driver for Linear Technology LTC2990 power monitor
*
* Copyright (C) 2014 Topic Embedded Products
* Author: Mike Looijmans <mike.looijmans@topic.nl>
*
* License: GPLv2
*
* This driver assumes the chip is wired as a dual current monitor, and
* reports the voltage drop across two series resistors. It also reports
* the chip's internal temperature and Vcc power supply voltage.
*/
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#define LTC2990_STATUS 0x00
#define LTC2990_CONTROL 0x01
#define LTC2990_TRIGGER 0x02
#define LTC2990_TINT_MSB 0x04
#define LTC2990_V1_MSB 0x06
#define LTC2990_V2_MSB 0x08
#define LTC2990_V3_MSB 0x0A
#define LTC2990_V4_MSB 0x0C
#define LTC2990_VCC_MSB 0x0E
#define LTC2990_CONTROL_KELVIN BIT(7)
#define LTC2990_CONTROL_SINGLE BIT(6)
#define LTC2990_CONTROL_MEASURE_ALL (0x3 << 3)
#define LTC2990_CONTROL_MODE_CURRENT 0x06
#define LTC2990_CONTROL_MODE_VOLTAGE 0x07
/* convert raw register value to sign-extended integer in 16-bit range */
static int ltc2990_voltage_to_int(int raw)
{
if (raw & BIT(14))
return -(0x4000 - (raw & 0x3FFF)) << 2;
else
return (raw & 0x3FFF) << 2;
}
/* Return the converted value from the given register in uV or mC */
static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
{
int val;
val = i2c_smbus_read_word_swapped(i2c, reg);
if (unlikely(val < 0))
return val;
switch (reg) {
case LTC2990_TINT_MSB:
/* internal temp, 0.0625 degrees/LSB, 13-bit */
val = (val & 0x1FFF) << 3;
*result = (val * 1000) >> 7;
break;
case LTC2990_V1_MSB:
case LTC2990_V3_MSB:
/* Vx-Vy, 19.42uV/LSB. Depends on mode. */
*result = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);
break;
case LTC2990_VCC_MSB:
/* Vcc, 305.18μV/LSB, 2.5V offset */
*result = (ltc2990_voltage_to_int(val) * 30518 /
(4 * 100 * 1000)) + 2500;
break;
default:
return -EINVAL; /* won't happen, keep compiler happy */
}
return 0;
}
static ssize_t ltc2990_show_value(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
int value;
int ret;
ret = ltc2990_get_value(dev_get_drvdata(dev), attr->index, &value);
if (unlikely(ret < 0))
return ret;
return snprintf(buf, PAGE_SIZE, "%d\n", value);
}
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ltc2990_show_value, NULL,
LTC2990_TINT_MSB);
static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2990_show_value, NULL,
LTC2990_V1_MSB);
static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc2990_show_value, NULL,
LTC2990_V3_MSB);
static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2990_show_value, NULL,
LTC2990_VCC_MSB);
static struct attribute *ltc2990_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_curr1_input.dev_attr.attr,
&sensor_dev_attr_curr2_input.dev_attr.attr,
&sensor_dev_attr_in0_input.dev_attr.attr,
NULL,
};
ATTRIBUTE_GROUPS(ltc2990);
static int ltc2990_i2c_probe(struct i2c_client *i2c,
const struct i2c_device_id *id)
{
int ret;
struct device *hwmon_dev;
if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA))
return -ENODEV;
/* Setup continuous mode, current monitor */
ret = i2c_smbus_write_byte_data(i2c, LTC2990_CONTROL,
LTC2990_CONTROL_MEASURE_ALL |
LTC2990_CONTROL_MODE_CURRENT);
if (ret < 0) {
dev_err(&i2c->dev, "Error: Failed to set control mode.\n");
return ret;
}
/* Trigger once to start continuous conversion */
ret = i2c_smbus_write_byte_data(i2c, LTC2990_TRIGGER, 1);
if (ret < 0) {
dev_err(&i2c->dev, "Error: Failed to start acquisition.\n");
return ret;
}
hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev,
i2c->name,
i2c,
ltc2990_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id ltc2990_i2c_id[] = {
{ "ltc2990", 0 },
{}
};
MODULE_DEVICE_TABLE(i2c, ltc2990_i2c_id);
static struct i2c_driver ltc2990_i2c_driver = {
.driver = {
.name = "ltc2990",
},
.probe = ltc2990_i2c_probe,
.id_table = ltc2990_i2c_id,
};
module_i2c_driver(ltc2990_i2c_driver);
MODULE_DESCRIPTION("LTC2990 Sensor Driver");
MODULE_AUTHOR("Topic Embedded Products");
MODULE_LICENSE("GPL v2");
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