diff options
Diffstat (limited to 'drivers/hwmon/ltc2990.c')
| -rw-r--r-- | drivers/hwmon/ltc2990.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/drivers/hwmon/ltc2990.c b/drivers/hwmon/ltc2990.c new file mode 100644 index 000000000..8f8fe059a --- /dev/null +++ b/drivers/hwmon/ltc2990.c @@ -0,0 +1,161 @@ +/* + * 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"); |