ltc2990.c 4.26 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161
/*
 * 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");