hwmon: New driver for the SMSC EMC6W201

This is a new driver for the SMSC EMC6W201 hardware monitoring device.
The device is functionally close to the EMC6D100 series, but is
register-incompatible.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Harry G McGavran Jr <w5pny@arrl.net>
Tested-by: Jeff Rickman <jrickman@myamigos.us>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>

Documentation/hwmon/emc6w201

@@ -0,0 +1,42 @@
+Kernel driver emc6w201
+======================
+
+Supported chips:
+  * SMSC EMC6W201
+    Prefix: 'emc6w201'
+    Addresses scanned: I2C 0x2c, 0x2d, 0x2e
+    Datasheet: Not public
+
+Author: Jean Delvare <khali@linux-fr.org>
+
+
+Description
+-----------
+
+From the datasheet:
+
+"The EMC6W201 is an environmental monitoring device with automatic fan
+control capability and enhanced system acoustics for noise suppression.
+This ACPI compliant device provides hardware monitoring for up to six
+voltages (including its own VCC) and five external thermal sensors,
+measures the speed of up to five fans, and controls the speed of
+multiple DC fans using three Pulse Width Modulator (PWM) outputs. Note
+that it is possible to control more than three fans by connecting two
+fans to one PWM output. The EMC6W201 will be available in a 36-pin
+QFN package."
+
+The device is functionally close to the EMC6D100 series, but is
+register-incompatible.
+
+The driver currently only supports the monitoring of the voltages,
+temperatures and fan speeds. Limits can be changed. Alarms are not
+supported, and neither is fan speed control.
+
+
+Known Systems With EMC6W201
+---------------------------
+
+The EMC6W201 is a rare device, only found on a few systems, made in
+2005 and 2006. Known systems with this device:
+* Dell Precision 670 workstation
+* Gigabyte 2CEWH mainboard