4 files changed, 219 insertions, 0 deletions

diff --git a/Documentation/hwmon/ltc2990 b/Documentation/hwmon/ltc2990
new file mode 100644
index 000000000000..c25211e90bdc
--- /dev/null
+++ b/Documentation/hwmon/ltc2990
@@ -0,0 +1,43 @@
+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.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 60fb80bd353d..852c8a85e1e8 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -685,6 +685,20 @@ config SENSORS_LTC2945
           This driver can also be built as a module. If so, the module will
           be called ltc2945.
 
+config SENSORS_LTC2990
+        tristate "Linear Technology LTC2990 (current monitoring mode only)"
+        depends on I2C
+        help
+          If you say yes here you get support for Linear Technology LTC2990
+          I2C System Monitor. The LTC2990 supports a combination of voltage,
+          current and temperature monitoring, but in addition to the Vcc supply
+          voltage and chip temperature, this driver currently only supports
+          reading two currents by measuring two differential voltages across
+          series resistors.
+
+          This driver can also be built as a module. If so, the module will
+          be called ltc2990.
+
 config SENSORS_LTC4151
         tristate "Linear Technology LTC4151"
         depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index cfc09711810c..a7ecaf2f29aa 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -100,6 +100,7 @@ obj-$(CONFIG_SENSORS_LM95234)	+= lm95234.o
 obj-$(CONFIG_SENSORS_LM95241)   += lm95241.o
 obj-$(CONFIG_SENSORS_LM95245)   += lm95245.o
 obj-$(CONFIG_SENSORS_LTC2945)   += ltc2945.o
+obj-$(CONFIG_SENSORS_LTC2990)   += ltc2990.o
 obj-$(CONFIG_SENSORS_LTC4151)   += ltc4151.o
 obj-$(CONFIG_SENSORS_LTC4215)   += ltc4215.o
 obj-$(CONFIG_SENSORS_LTC4222)   += ltc4222.o
diff --git a/drivers/hwmon/ltc2990.c b/drivers/hwmon/ltc2990.c
new file mode 100644
index 000000000000..8f8fe059ab48
--- /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");