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"); 162