dt-bindings: input: atmel_mxt_ts: Document atmel,wakeup-method and WAKE line GPIO

Some Atmel touchscreen controllers have a WAKE line that needs to be
asserted low in order to wake up controller from a deep sleep. Document
the wakeup methods and the new GPIO properties.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20210302102158.10533-2-digetx@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/atmel,maxtouch.yaml

@@ -39,6 +39,13 @@ properties:
       (active low). The line must be flagged with
       GPIO_ACTIVE_LOW.
 
+  wake-gpios:
+    maxItems: 1
+    description:
+      Optional GPIO specifier for the touchscreen's wake pin
+      (active low). The line must be flagged with
+      GPIO_ACTIVE_LOW.
+
   linux,gpio-keymap:
     $ref: /schemas/types.yaml#/definitions/uint32-array
     description: |
@@ -53,6 +60,26 @@ properties:
       or experiment to determine which bit corresponds to which input. Use
       KEY_RESERVED for unused padding values.
 
+  atmel,wakeup-method:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      The WAKE line is an active-low input that is used to wake up the touch
+      controller from deep-sleep mode before communication with the controller
+      could be started. This optional feature used to minimize current
+      consumption when the controller is in deep sleep mode. This feature is
+      relevant only to some controller families, like mXT1386 controller for
+      example.
+
+      The WAKE pin can be connected in one of the following ways:
+       1) left permanently low
+       2) connected to the I2C-compatible SCL pin
+       3) connected to a GPIO pin on the host
+    enum:
+      - 0 # ATMEL_MXT_WAKEUP_NONE
+      - 1 # ATMEL_MXT_WAKEUP_I2C_SCL
+      - 2 # ATMEL_MXT_WAKEUP_GPIO
+    default: 0
+
 required:
   - compatible
   - reg
@@ -63,6 +90,7 @@ additionalProperties: false
 examples:
   - |
     #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/input/atmel-maxtouch.h>
     #include <dt-bindings/gpio/gpio.h>
     i2c {
       #address-cells = <1>;
@@ -75,6 +103,7 @@ examples:
         reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
         vdda-supply = <&ab8500_ldo_aux2_reg>;
         vdd-supply = <&ab8500_ldo_aux5_reg>;
+        atmel,wakeup-method = <ATMEL_MXT_WAKEUP_I2C_SCL>;
       };
     };
 

include/dt-bindings/input/atmel-maxtouch.h

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef _DT_BINDINGS_ATMEL_MAXTOUCH_H
+#define _DT_BINDINGS_ATMEL_MAXTOUCH_H
+
+#define ATMEL_MXT_WAKEUP_NONE		0
+#define ATMEL_MXT_WAKEUP_I2C_SCL	1
+#define ATMEL_MXT_WAKEUP_GPIO		2
+
+#endif /* _DT_BINDINGS_ATMEL_MAXTOUCH_H */