i2c/busses: Add support for Diolan U2C-12 USB-I2C adapter

This patch adds support for the Diolan U2C-12 USB-I2C adapter.
It also updates MAINTAINERS to list the author as maintainer.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/Documentation/i2c/busses/i2c-diolan-u2c b/Documentation/i2c/busses/i2c-diolan-u2c
new file mode 100644
index 0000000..30fe4bb
--- /dev/null
+++ b/Documentation/i2c/busses/i2c-diolan-u2c
@@ -0,0 +1,26 @@
+Kernel driver i2c-diolan-u2c
+
+Supported adapters:
+  * Diolan U2C-12 I2C-USB adapter
+    Documentation:
+	http://www.diolan.com/i2c/u2c12.html
+
+Author: Guenter Roeck <guenter.roeck@ericsson.com>
+
+Description
+-----------
+
+This is the driver for the Diolan U2C-12 USB-I2C adapter.
+
+The Diolan U2C-12 I2C-USB Adapter provides a low cost solution to connect
+a computer to I2C slave devices using a USB interface. It also supports
+connectivity to SPI devices.
+
+This driver only supports the I2C interface of U2C-12. The driver does not use
+interrupts.
+
+
+Module parameters
+-----------------
+
+* frequency: I2C bus frequency