blob: 8f8fe059ab48aacc918b5dabcc698460aa0e9a89 [file] [log] [blame]
Mike Looijmansdf922702016-01-15 10:54:59 +01001/*
2 * Driver for Linear Technology LTC2990 power monitor
3 *
4 * Copyright (C) 2014 Topic Embedded Products
5 * Author: Mike Looijmans <mike.looijmans@topic.nl>
6 *
7 * License: GPLv2
8 *
9 * This driver assumes the chip is wired as a dual current monitor, and
10 * reports the voltage drop across two series resistors. It also reports
11 * the chip's internal temperature and Vcc power supply voltage.
12 */
13
14#include <linux/err.h>
15#include <linux/hwmon.h>
16#include <linux/hwmon-sysfs.h>
17#include <linux/i2c.h>
18#include <linux/kernel.h>
19#include <linux/module.h>
20
21#define LTC2990_STATUS 0x00
22#define LTC2990_CONTROL 0x01
23#define LTC2990_TRIGGER 0x02
24#define LTC2990_TINT_MSB 0x04
25#define LTC2990_V1_MSB 0x06
26#define LTC2990_V2_MSB 0x08
27#define LTC2990_V3_MSB 0x0A
28#define LTC2990_V4_MSB 0x0C
29#define LTC2990_VCC_MSB 0x0E
30
31#define LTC2990_CONTROL_KELVIN BIT(7)
32#define LTC2990_CONTROL_SINGLE BIT(6)
33#define LTC2990_CONTROL_MEASURE_ALL (0x3 << 3)
34#define LTC2990_CONTROL_MODE_CURRENT 0x06
35#define LTC2990_CONTROL_MODE_VOLTAGE 0x07
36
37/* convert raw register value to sign-extended integer in 16-bit range */
38static int ltc2990_voltage_to_int(int raw)
39{
40 if (raw & BIT(14))
41 return -(0x4000 - (raw & 0x3FFF)) << 2;
42 else
43 return (raw & 0x3FFF) << 2;
44}
45
46/* Return the converted value from the given register in uV or mC */
47static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
48{
49 int val;
50
51 val = i2c_smbus_read_word_swapped(i2c, reg);
52 if (unlikely(val < 0))
53 return val;
54
55 switch (reg) {
56 case LTC2990_TINT_MSB:
57 /* internal temp, 0.0625 degrees/LSB, 13-bit */
58 val = (val & 0x1FFF) << 3;
59 *result = (val * 1000) >> 7;
60 break;
61 case LTC2990_V1_MSB:
62 case LTC2990_V3_MSB:
63 /* Vx-Vy, 19.42uV/LSB. Depends on mode. */
64 *result = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);
65 break;
66 case LTC2990_VCC_MSB:
67 /* Vcc, 305.18μV/LSB, 2.5V offset */
68 *result = (ltc2990_voltage_to_int(val) * 30518 /
69 (4 * 100 * 1000)) + 2500;
70 break;
71 default:
72 return -EINVAL; /* won't happen, keep compiler happy */
73 }
74
75 return 0;
76}
77
78static ssize_t ltc2990_show_value(struct device *dev,
79 struct device_attribute *da, char *buf)
80{
81 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
82 int value;
83 int ret;
84
85 ret = ltc2990_get_value(dev_get_drvdata(dev), attr->index, &value);
86 if (unlikely(ret < 0))
87 return ret;
88
89 return snprintf(buf, PAGE_SIZE, "%d\n", value);
90}
91
92static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ltc2990_show_value, NULL,
93 LTC2990_TINT_MSB);
94static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2990_show_value, NULL,
95 LTC2990_V1_MSB);
96static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc2990_show_value, NULL,
97 LTC2990_V3_MSB);
98static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2990_show_value, NULL,
99 LTC2990_VCC_MSB);
100
101static struct attribute *ltc2990_attrs[] = {
102 &sensor_dev_attr_temp1_input.dev_attr.attr,
103 &sensor_dev_attr_curr1_input.dev_attr.attr,
104 &sensor_dev_attr_curr2_input.dev_attr.attr,
105 &sensor_dev_attr_in0_input.dev_attr.attr,
106 NULL,
107};
108ATTRIBUTE_GROUPS(ltc2990);
109
110static int ltc2990_i2c_probe(struct i2c_client *i2c,
111 const struct i2c_device_id *id)
112{
113 int ret;
114 struct device *hwmon_dev;
115
116 if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
117 I2C_FUNC_SMBUS_WORD_DATA))
118 return -ENODEV;
119
120 /* Setup continuous mode, current monitor */
121 ret = i2c_smbus_write_byte_data(i2c, LTC2990_CONTROL,
122 LTC2990_CONTROL_MEASURE_ALL |
123 LTC2990_CONTROL_MODE_CURRENT);
124 if (ret < 0) {
125 dev_err(&i2c->dev, "Error: Failed to set control mode.\n");
126 return ret;
127 }
128 /* Trigger once to start continuous conversion */
129 ret = i2c_smbus_write_byte_data(i2c, LTC2990_TRIGGER, 1);
130 if (ret < 0) {
131 dev_err(&i2c->dev, "Error: Failed to start acquisition.\n");
132 return ret;
133 }
134
135 hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev,
136 i2c->name,
137 i2c,
138 ltc2990_groups);
139
140 return PTR_ERR_OR_ZERO(hwmon_dev);
141}
142
143static const struct i2c_device_id ltc2990_i2c_id[] = {
144 { "ltc2990", 0 },
145 {}
146};
147MODULE_DEVICE_TABLE(i2c, ltc2990_i2c_id);
148
149static struct i2c_driver ltc2990_i2c_driver = {
150 .driver = {
151 .name = "ltc2990",
152 },
153 .probe = ltc2990_i2c_probe,
154 .id_table = ltc2990_i2c_id,
155};
156
157module_i2c_driver(ltc2990_i2c_driver);
158
159MODULE_DESCRIPTION("LTC2990 Sensor Driver");
160MODULE_AUTHOR("Topic Embedded Products");
161MODULE_LICENSE("GPL v2");