| Mike Looijmans | df92270 | 2016-01-15 10:54:59 +0100 | [diff] [blame] | 1 | /* |
| 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 */ |
| 38 | static 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 */ |
| 47 | static 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 | |
| 78 | static 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 | |
| 92 | static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ltc2990_show_value, NULL, |
| 93 | LTC2990_TINT_MSB); |
| 94 | static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2990_show_value, NULL, |
| 95 | LTC2990_V1_MSB); |
| 96 | static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc2990_show_value, NULL, |
| 97 | LTC2990_V3_MSB); |
| 98 | static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2990_show_value, NULL, |
| 99 | LTC2990_VCC_MSB); |
| 100 | |
| 101 | static 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 | }; |
| 108 | ATTRIBUTE_GROUPS(ltc2990); |
| 109 | |
| 110 | static 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 | |
| 143 | static const struct i2c_device_id ltc2990_i2c_id[] = { |
| 144 | { "ltc2990", 0 }, |
| 145 | {} |
| 146 | }; |
| 147 | MODULE_DEVICE_TABLE(i2c, ltc2990_i2c_id); |
| 148 | |
| 149 | static 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 | |
| 157 | module_i2c_driver(ltc2990_i2c_driver); |
| 158 | |
| 159 | MODULE_DESCRIPTION("LTC2990 Sensor Driver"); |
| 160 | MODULE_AUTHOR("Topic Embedded Products"); |
| 161 | MODULE_LICENSE("GPL v2"); |