dt-bindings: cros-ec: Add ChromeOS fingerprint binding

Add a binding to describe the fingerprint processor found on Chromebooks
with a fingerprint sensor. Previously we've been describing this with
the google,cros-ec-spi binding but it lacks gpio and regulator control
used during firmware flashing.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc: <devicetree@vger.kernel.org>
Cc: <chrome-platform@lists.linux.dev>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Craig Hesling <hesling@chromium.org>
Cc: Tom Hughes <tomhughes@chromium.org>
Cc: Alexandru M Stan <amstan@chromium.org>
Cc: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20221026003641.2688765-3-swboyd@chromium.org

Documentation/devicetree/bindings/mfd/google,cros-ec.yaml

@@ -25,6 +25,11 @@ properties:
       - description:
           For implementations of the EC connected through SPI.
         const: google,cros-ec-spi
+      - description:
+          For implementations of the FPMCU connected through SPI.
+        items:
+          - const: google,cros-ec-fp
+          - const: google,cros-ec-spi
       - description:
           For implementations of the EC connected through RPMSG.
         const: google,cros-ec-rpmsg
@@ -67,6 +72,15 @@ properties:
   interrupts:
     maxItems: 1
 
+  reset-gpios:
+    maxItems: 1
+
+  boot0-gpios:
+    maxItems: 1
+    description: Assert for bootloader mode.
+
+  vdd-supply: true
+
   wakeup-source:
     description: Button can wake-up the system.
 
@@ -177,6 +191,41 @@ allOf:
         - reg
         - interrupts
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: google,cros-ec-fp
+    then:
+      properties:
+        '#address-cells': false
+        '#size-cells': false
+        typec: false
+        ec-pwm: false
+        kbd-led-backlight: false
+        keyboard-controller: false
+        proximity: false
+        codecs: false
+        cbas: false
+
+      patternProperties:
+        "^i2c-tunnel[0-9]*$": false
+        "^regulator@[0-9]+$": false
+        "^extcon[0-9]*$": false
+
+      # Using additionalProperties: false here and
+      # listing true properties doesn't work
+
+      required:
+        - reset-gpios
+        - boot0-gpios
+        - vdd-supply
+    else:
+      properties:
+        reset-gpios: false
+        boot0-gpios: false
+        vdd-supply: false
+
 additionalProperties: false
 
 examples:
@@ -232,4 +281,22 @@ examples:
             compatible = "google,cros-ec-rpmsg";
         };
     };
+
+  # Example for FPMCU
+  - |
+    spi0 {
+      #address-cells = <0x1>;
+      #size-cells = <0x0>;
+
+      ec@0 {
+        compatible = "google,cros-ec-fp", "google,cros-ec-spi";
+        reg = <0x0>;
+        interrupt-parent = <&gpio_controller>;
+        interrupts = <4 IRQ_TYPE_LEVEL_LOW>;
+        spi-max-frequency = <3000000>;
+        reset-gpios = <&gpio_controller 5 GPIO_ACTIVE_LOW>;
+        boot0-gpios = <&gpio_controller 10 GPIO_ACTIVE_HIGH>;
+        vdd-supply = <&pp3300_fp_mcu>;
+      };
+    };
 ...