input: Extend matrix-keypad device tree binding

Some matrix keypad drivers can support different numbers of rows and
columns. Add a generic binding for these.

Implementation note:

In order to implement this binding in the kernel, we will need to modify
matrix_keypad_() to look up the number of rows and cols in
the keymap. Perhaps this could be done by passing 0 for these parameters?
Many of the parameters can already be set to NULL. Ick.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Documentation/devicetree/bindings/input/lpc32xx-key.txt

 NXP LPC32xx Key Scan Interface
 
+This binding is based on the matrix-keymap binding with the following
+changes:
+
 Required Properties:
 - compatible: Should be "nxp,lpc3220-key"
 - reg: Physical base address of the controller and length of memory mapped
   region.
 - interrupts: The interrupt number to the cpu.
-- keypad,num-rows: Number of rows and columns, e.g. 1: 1x1, 6: 6x6
-- keypad,num-columns: Must be equal to keypad,num-rows since LPC32xx only
-  supports square matrices
 - nxp,debounce-delay-ms: Debounce delay in ms
 - nxp,scan-delay-ms: Repeated scan period in ms
 - linux,keymap: the key-code to be reported when the key is pressed
   and released, see also
   Documentation/devicetree/bindings/input/matrix-keymap.txt
 
+Note: keypad,num-rows and keypad,num-columns are required, and must be equal
+since LPC32xx only supports square matrices
+
 Example:
 
 	key@40050000 {

Documentation/devicetree/bindings/input/matrix-keymap.txt

@@ -9,6 +9,12 @@ Required properties:
 	row << 24 | column << 16 | key-code
 
 Optional properties:
+Properties for the number of rows and columns are optional because some
+drivers will use fixed values for these.
+- keypad,num-rows: Number of row lines connected to the keypad controller.
+- keypad,num-columns: Number of column lines connected to the keypad
+  controller.
+
 Some users of this binding might choose to specify secondary keymaps for
 cases where there is a modifier key such as a Fn key. Proposed names
 for said properties are "linux,fn-keymap" or with another descriptive
@@ -17,3 +23,5 @@ word for the modifier other from "Fn".
 Example:
 	linux,keymap = < 0x00030012
 			 0x0102003a >;
+	keypad,num-rows = <2>;
+	keypad,num-columns = <8>;

Documentation/devicetree/bindings/input/omap-keypad.txt

@@ -6,19 +6,16 @@ A key can be placed at each intersection of a unique row and a unique column.
 The keypad controller can sense a key-press and key-release and report the
 event using a interrupt to the cpu.
 
+This binding is based on the matrix-keymap binding with the following
+changes:
+
+keypad,num-rows and keypad,num-columns are required.
+
 Required SoC Specific Properties:
 - compatible: should be one of the following
    - "ti,omap4-keypad": For controllers compatible with omap4 keypad
       controller.
 
-Required Board Specific Properties, in addition to those specified by
-the shared matrix-keyboard bindings:
-- keypad,num-rows: Number of row lines connected to the keypad
-  controller.
-
-- keypad,num-columns: Number of column lines connected to the
-  keypad controller.
-
 Optional Properties specific to linux:
 - linux,keypad-no-autorepeat: do no enable autorepeat feature.
 

Documentation/devicetree/bindings/input/tca8418_keypad.txt

+This binding is based on the matrix-keymap binding with the following
+changes:
+
+keypad,num-rows and keypad,num-columns are required.
 
 Required properties:
 - compatible: "ti,tca8418"
 - reg: the I2C address
 - interrupts: IRQ line number, should trigger on falling edge
-- keypad,num-rows: The number of rows
-- keypad,num-columns: The number of columns
 - linux,keymap: Keys definitions, see keypad-matrix.