dt-bindings: rtc: Add YAML schemas for the generic RTC bindings

The real time clocks have a bunch of generic properties that are needed in
a device tree. Add a YAML schemas for those.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Documentation/devicetree/bindings/rtc/rtc.txt

-Generic device tree bindings for Real Time Clock devices
-========================================================
-
-This document describes generic bindings which can be used to describe Real Time
-Clock devices in a device tree.
-
-Required properties
--------------------
-
-- compatible : name of RTC device following generic names recommended practice.
-
-For other required properties e.g. to describe register sets,
-clocks, etc. check the binding documentation of the specific driver.
-
-Optional properties
--------------------
-
-- start-year : if provided, the default hardware range supported by the RTC is
-               shifted so the first usable year is the specified one.
-
-The following properties may not be supported by all drivers. However, if a
-driver wants to support one of the below features, it should adapt the bindings
-below.
-- trickle-resistor-ohms :   Selected resistor for trickle charger. Should be given
-                            if trickle charger should be enabled
-- trickle-diode-disable :   Do not use internal trickle charger diode Should be
-                            given if internal trickle charger diode should be
-                            disabled
-- wakeup-source :           Enables wake up of host system on alarm
-- quartz-load-femtofarads : The capacitive load of the quartz(x-tal),
-                            expressed in femto Farad (fF).
-                            The default value shall be listed (if optional),
-                            and likewise all valid values.
+This file has been moved to rtc.yaml.
 
 Trivial RTCs
 ------------

Documentation/devicetree/bindings/rtc/rtc.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/rtc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RTC Generic Binding
+
+maintainers:
+  - Alexandre Belloni <alexandre.belloni@bootlin.com>
+
+description: |
+  This document describes generic bindings which can be used to
+  describe Real Time Clock devices in a device tree.
+
+properties:
+  $nodename:
+    pattern: "^rtc(@.*|-[0-9a-f])*$"
+
+  quartz-load-femtofarads:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      The capacitive load of the quartz(x-tal), expressed in femto
+      Farad (fF). The default value shall be listed (if optional),
+      and likewise all valid values.
+
+  start-year:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      If provided, the default hardware range supported by the RTC is
+      shifted so the first usable year is the specified one.
+
+  trickle-diode-disable:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      Do not use internal trickle charger diode. Should be given if
+      internal trickle charger diode should be disabled.
+
+  trickle-resistor-ohms:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Selected resistor for trickle charger. Should be given
+      if trickle charger should be enabled.
+
+  wakeup-source:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      Enables wake up of host system on alarm.
+
+...