dt-bindings: img-ascii-lcd: Document a binding for simple ASCII LCDs

Add documentation for a devicetree binding for the simple ASCII LCD
displays found on development boards such as the MIPS Boston, MIPS Malta
& MIPS SEAD3 from Imagination Technologies.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14061/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Documentation/devicetree/bindings/auxdisplay/img-ascii-lcd.txt

+Binding for ASCII LCD displays on Imagination Technologies boards
+
+Required properties:
+- compatible : should be one of:
+    "img,boston-lcd"
+    "mti,malta-lcd"
+    "mti,sead3-lcd"
+
+Required properties for "img,boston-lcd":
+- reg : memory region locating the device registers
+
+Required properties for "mti,malta-lcd" or "mti,sead3-lcd":
+- regmap: phandle of the system controller containing the LCD registers
+- offset: offset in bytes to the LCD registers within the system controller
+
+The layout of the registers & properties of the display are determined
+from the compatible string, making this binding somewhat trivial.

MAINTAINERS

@@ -5964,6 +5964,11 @@ M:	Stanislaw Gruszka <stf_xl@wp.pl>
 S:	Maintained
 F:	drivers/usb/atm/ueagle-atm.c
 
+IMGTEC ASCII LCD DRIVER
+M:	Paul Burton <paul.burton@imgtec.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/auxdisplay/img-ascii-lcd.txt
+
 INA209 HARDWARE MONITOR DRIVER
 M:	Guenter Roeck <linux@roeck-us.net>
 L:	linux-hwmon@vger.kernel.org