hwmon: Add support for Texas Instruments ADS1015

Signed-off-by: Dirk Eibach <eibach@gdsys.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

Documentation/devicetree/bindings/hwmon/ads1015.txt

@@ -0,0 +1,29 @@
+ADS1015 (I2C)
+
+This device is a 12-bit A-D converter with 4 inputs.
+
+The inputs can be used single ended or in certain differential combinations.
+
+For configuration all possible combinations are mapped to 8 channels:
+0: Voltage over AIN0 and AIN1.
+1: Voltage over AIN0 and AIN3.
+2: Voltage over AIN1 and AIN3.
+3: Voltage over AIN2 and AIN3.
+4: Voltage over AIN0 and GND.
+5: Voltage over AIN1 and GND.
+6: Voltage over AIN2 and GND.
+7: Voltage over AIN3 and GND.
+
+Optional properties:
+
+ - exported-channels : exported_channels is a bitmask that specifies which
+		       channels should be accessable by the user.
+
+Example:
+ads1015@49 {
+	compatible = "ti,ads1015";
+	reg = <0x49>;
+	exported-channels = <0x14>;
+};
+
+In this example only channel 2 and 4 would be accessable by the user.