On Wed, May 4, 2016 at 6:51 AM, Rob Herring [off-list ref] wrote:

On Tue, May 03, 2016 at 10:13:31AM -0700, Grant Grundler wrote:

quoted

Add I2C driver for AtmegaXX capacitive touch device.

Signed-off-by: Hung-yu Wu <redacted>
Signed-off-by: Grant Grundler <redacted>
---
 .../bindings/input/atmel,atmegaxx_captouch.txt     |  34 +++

It is generally preferred that bindings are a separate patch.

ACK - I just discovered Documentation/devicetree/bindings/submitting-patches.txt
(which explains this in more detail)

quoted

 drivers/input/misc/Kconfig                         |  11 +
 drivers/input/misc/Makefile                        |   1 +
 drivers/input/misc/atmegaxx_captouch.c             | 278 +++++++++++++++++++++
 4 files changed, 324 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/atmel,atmegaxx_captouch.txt
 create mode 100644 drivers/input/misc/atmegaxx_captouch.c

For those that like to know how sausage is made, ChromeOS code review history here:
   https://chromium-review.googlesource.com/339950

Driver was tested with prototype HW and it reliably reports events correctly.
Manual testing was just using "evtest /dev/input/event0" and watch for events.

diff --git a/Documentation/devicetree/bindings/input/atmel,atmegaxx_captouch.txt b/Documentation/devicetree/bindings/input/atmel,atmegaxx_captouch.txt
new file mode 100644
index 0000000..07a4b0b
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/atmel,atmegaxx_captouch.txt

@@ -0,0 +1,34 @@
+Device tree bindings for Atmel AtmegaXX capacitive touch sensor
+
+The node for this device must be a child of a I2C controller node, as the
+device communicates via I2C.
+
+Required properties:
+
+     compatible:     Must be "atmel,atmegaxx_captouch".

No wildcards in the compatible strings. Use the specific devices.

Sorry, I don't understand - What is a wildcard in this context?

I also just discovered
Documentation/devicetree/bindings/submitting-patches.txt and the "5)
the wildcard" text doesn't seem to match the usage here.

Also, use hyphen rather than underscore.

ACK - I have no clue why - I've been scrounging around in
Documentation and haven't stumbled across "coding style" for device
tree document.

However, if the device is only a touch controller, then '_captouch' is not needed.
The part number is sufficient to identify the device.

atmegaxx is an Atmel microcontroller series and in this particular
case used to drive a capacitive touch input device (just buttons).
Since the microcontroller can be used for "anything", "captouch" is
sort of the "model" of this implementation.

quoted

+     reg:            The I2C slave address of the device.
+     interrupts:     Property describing the interrupt line the device
+                     is connected to. The device only has one interrupt
+                     source.
+     linux,keycodes: Specifies an array of numeric keycode values to
+                     be used for reporting button presses. The array can
+                     contain up to 8 entries.
+
+Optional properties:
+
+     autorepeat:     Enables the Linux input system's autorepeat
+                     feature on the input device.
+
+Example:
+
+     atmegaxx_captouch@51 {

atmegaxx@51 (with actual part number)

atmegaxx_captouch (or -captouch) is how Atmel has been referring to
this implementation. I'm not aware of any other part number or model
number.

quoted

+             compatible = "atmel,atmegaxx_captouch";
+             reg = <0x51>;
+             interrupt-parent = <&tlmm>;
+             interrupts = <67 IRQ_TYPE_EDGE_FALLING>;
+             linux,keycodes = <BTN_0>, <BTN_1>,
+                     <BTN_2>, <BTN_3>,
+                     <BTN_4>, <BTN_5>,
+                     <BTN_6>, <BTN_7>;
+             autorepeat;
+     };

Thanks for the feedback!
I'll repost with s/_/-/ fix after naming is clear.

thanks,
grant