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