On 15/08/14 13:01, Javier Martinez Canillas wrote:

quoted

By passing all these keycodes the touchpad worked as expected for me and the
driver did the same than the Chrome OS driver that has these keycodes hardcoded
when is_tp is true.

quoted

at the protocol guide for T19.

I don't have access to proper documentation and I wouldn't expect people to have
access to non-public docs in order to use a Device Tree binding.

That's why I wanted to document an example, so using this property could be
easier for others and they shouldn't have to look at the driver in order to
figure it out (and getting it wrong as you said :) )

So it would be great if you could provide an example on how this is supposed to
be used.

Any comments on this? I would really appreciate if you can expand on how
this DT property is supposed to be used so I can re-spin the atmel support
patch for Peach boards.

The below patch improves the documentation for the gpio-property. Stephen
Warren has a good example here:
https://github.com/swarren/linux-tegra/commit/09789801

trackpad@4b {
  compatible = "atmel,maxtouch";
  reg = <0x4b>;
  interrupt-parent = <&gpio>;
  interrupts = <TEGRA_GPIO(W, 3) IRQ_TYPE_LEVEL_LOW>;
  linux,gpio-keymap = <0 0 0 BTN_LEFT>;
};

This maps BTN_LEFT to the 4th bit of the T19 message. I haven't looked up
what GPIO number that corresponds to on the mXT224SL that he has, it varies
with the particular maXTouch device you have.

Hope this helps.

Signed-off-by: Nick Dyer <redacted>
---
 Documentation/devicetree/bindings/input/atmel,maxtouch.txt | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt

b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt
index baef432..1852906 100644

--- a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt
+++ b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt

@@ -11,10 +11,17 @@ Required properties:

 Optional properties for main touchpad device:

-- linux,gpio-keymap: An array of up to 4 entries indicating the Linux
-    keycode generated by each GPIO. Linux keycodes are defined in
+- linux,gpio-keymap: When enabled, the SPT_GPIOPWN_T19 object sends messages
+    on GPIO bit changes. An array of up to 8 entries can be provided
+    indicating the Linux keycode mapped to each bit of the status byte,
+    starting at the LSB. Linux keycodes are defined in
     <dt-bindings/input/input.h>.

+    Note: the numbering of the GPIOs and the bit they start at varies between
+    maXTouch devices. You must either refer to the documentation, or
+    experiment to determine which bit corresponds to which input. Use
+    KEY_RESERVED for unused padding values.
+
 Example:

        touch@4b {

-- 
1.9.1