--- /dev/null
+Kernel driver ltc2990
+=====================
+
+Supported chips:
+ * Linear Technology LTC2990
+ Prefix: 'ltc2990'
+ Addresses scanned: -
+ Datasheet: http://www.linear.com/product/ltc2990
+
+Author: Mike Looijmans <mike.looijmans@topic.nl>
+
+
+Description
+-----------
+
+LTC2990 is a Quad I2C Voltage, Current and Temperature Monitor.
+The chip's inputs can measure 4 voltages, or two inputs together (1+2 and 3+4)
+can be combined to measure a differential voltage, which is typically used to
+measure current through a series resistor, or a temperature.
+
+This driver currently uses the 2x differential mode only. In order to support
+other modes, the driver will need to be expanded.
+
+
+Usage Notes
+-----------
+
+This driver does not probe for PMBus devices. You will have to instantiate
+devices explicitly.
+
+
+Sysfs attributes
+----------------
+
+The "curr*_input" measurements actually report the voltage drop across the
+input pins in microvolts. This is equivalent to the current through a 1mOhm
+sense resistor. Divide the reported value by the actual sense resistor value
+in mOhm to get the actual value.
+
+in0_input Voltage at Vcc pin in millivolt (range 2.5V to 5V)
+temp1_input Internal chip temperature in millidegrees Celcius
+curr1_input Current in mA across v1-v2 assuming a 1mOhm sense resistor.
+curr2_input Current in mA across v3-v4 assuming a 1mOhm sense resistor.
--- /dev/null
+/*
+ * 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");
projects / karo-tx-linux.git / commitdiff