hwmon: Driver for Linear Technologies LTC4260

LTC4260 is a Positive Voltage Hot Swap Controller.
The driver currently only supports voltage monitoring, not voltage control.

Signed-off-by: Guenter Roeck <[email protected]>

Documentation/hwmon/ltc4260

@@ -0,0 +1,56 @@
+Kernel driver ltc4260
+=====================
+
+Supported chips:
+  * Linear Technology LTC4260
+    Prefix: 'ltc4260'
+    Addresses scanned: -
+    Datasheet:
+        http://cds.linear.com/docs/en/datasheet/4260fc.pdf
+
+Author: Guenter Roeck <[email protected]>
+
+
+Description
+-----------
+
+The LTC4260 Hot Swap controller allows a board to be safely inserted
+and removed from a live backplane.
+
+
+Usage Notes
+-----------
+
+This driver does not probe for LTC4260 devices, since there is no register
+which can be safely used to identify the chip. You will have to instantiate
+the devices explicitly.
+
+Example: the following will load the driver for an LTC4260 at address 0x10
+on I2C bus #1:
+$ modprobe ltc4260
+$ echo ltc4260 0x10 > /sys/bus/i2c/devices/i2c-1/new_device
+
+
+Sysfs entries
+-------------
+
+Voltage readings provided by this driver are reported as obtained from the ADC
+registers. If a set of voltage divider resistors is installed, calculate the
+real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the
+value of the divider resistor against the measured voltage and R2 is the value
+of the divider resistor against Ground.
+
+Current reading provided by this driver is reported as obtained from the ADC
+Current Sense register. The reported value assumes that a 1 mOhm sense resistor
+is installed. If a different sense resistor is installed, calculate the real
+current by dividing the reported value by the sense resistor value in mOhm.
+
+in1_input		SOURCE voltage (mV)
+in1_min_alarm		Undervoltage alarm
+in1_max_alarm		Overvoltage alarm
+
+in2_input		ADIN voltage (mV)
+in2_alarm		Power bad alarm
+
+curr1_input		SENSE current (mA)
+curr1_alarm		SENSE overcurrent alarm