hwmon: (pmbus) Document Infineon PXE1610 driver

Added documentation for Infineon PXE1610 driver
Signed-off-by: Vijay Khemka <vijaykhemka@fb.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/pxe1610

+Kernel driver pxe1610
+=====================
+
+Supported chips:
+  * Infineon PXE1610
+    Prefix: 'pxe1610'
+    Addresses scanned: -
+    Datasheet: Datasheet is not publicly available.
+
+  * Infineon PXE1110
+    Prefix: 'pxe1110'
+    Addresses scanned: -
+    Datasheet: Datasheet is not publicly available.
+
+  * Infineon PXM1310
+    Prefix: 'pxm1310'
+    Addresses scanned: -
+    Datasheet: Datasheet is not publicly available.
+
+Author: Vijay Khemka <vijaykhemka@fb.com>
+
+
+Description
+-----------
+
+PXE1610/PXE1110 are Multi-rail/Multiphase Digital Controllers
+and compliant to
+	-- Intel VR13 DC-DC converter specifications.
+	-- Intel SVID protocol.
+Used for Vcore power regulation for Intel VR13 based microprocessors
+	-- Servers, Workstations, and High-end desktops
+
+PXM1310 is a Multi-rail Controller and it is compliant to
+	-- Intel VR13 DC-DC converter specifications.
+	-- Intel SVID protocol.
+Used for DDR3/DDR4 Memory power regulation for Intel VR13 and
+IMVP8 based systems
+
+
+Usage Notes
+-----------
+
+This driver does not probe for PMBus devices. You will have
+to instantiate devices explicitly.
+
+Example: the following commands will load the driver for an PXE1610
+at address 0x70 on I2C bus #4:
+
+# modprobe pxe1610
+# echo pxe1610 0x70 > /sys/bus/i2c/devices/i2c-4/new_device
+
+It can also be instantiated by declaring in device tree
+
+
+Sysfs attributes
+----------------
+
+curr1_label		"iin"
+curr1_input		Measured input current
+curr1_alarm		Current high alarm
+
+curr[2-4]_label		"iout[1-3]"
+curr[2-4]_input		Measured output current
+curr[2-4]_crit		Critical maximum current
+curr[2-4]_crit_alarm	Current critical high alarm
+
+in1_label		"vin"
+in1_input		Measured input voltage
+in1_crit		Critical maximum input voltage
+in1_crit_alarm		Input voltage critical high alarm
+
+in[2-4]_label		"vout[1-3]"
+in[2-4]_input		Measured output voltage
+in[2-4]_lcrit		Critical minimum output voltage
+in[2-4]_lcrit_alarm	Output voltage critical low alarm
+in[2-4]_crit		Critical maximum output voltage
+in[2-4]_crit_alarm	Output voltage critical high alarm
+
+power1_label		"pin"
+power1_input		Measured input power
+power1_alarm		Input power high alarm
+
+power[2-4]_label	"pout[1-3]"
+power[2-4]_input	Measured output power
+
+temp[1-3]_input		Measured temperature
+temp[1-3]_crit		Critical high temperature
+temp[1-3]_crit_alarm	Chip temperature critical high alarm
+temp[1-3]_max		Maximum temperature
+temp[1-3]_max_alarm	Chip temperature high alarm