[PATCH v5 2/9] dt-bindings: clock: ma35d1: Document the missing crystal inputs

[Miquel Raynal]

The MA35D1 clock controller takes two crystal oscillator inputs from
the board:
- HXT, a high-speed 24 MHz crystal for most of the system
- LXT, a low-speed 32.768 kHz crytal for the RTC and low power modes

So far the binding was expecting a single crystal. The example named it
HXT, but no real definition for it was given. LXT was not even
described. In order to remain backward compatible, we will continue to
allow either one (HXT) or two (HXT then LXT) input clocks. I propose to
give those phandles a name to clarify what these entries expect, but I'm
not listing the clock-names property in the required block, for backward
compatibility. The rates are fixed by the TRM, so even if the second
oscillator is not described, the OS can make an educated guess.

Fixes: 2f8b5eb589cb ("dt-bindings: clock: nuvoton: add binding for ma35d1 clock controller")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
 .../devicetree/bindings/clock/nuvoton,ma35d1-clk.yaml    | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/clock/nuvoton,ma35d1-clk.yaml b/Documentation/devicetree/bindings/clock/nuvoton,ma35d1-clk.yaml
index 8f0c43683729..9649feda8d7a 100644
--- a/Documentation/devicetree/bindings/clock/nuvoton,ma35d1-clk.yaml
+++ b/Documentation/devicetree/bindings/clock/nuvoton,ma35d1-clk.yaml
@@ -29,7 +29,18 @@ properties:
     const: 1
 
   clocks:
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
+    description:
+      The controller takes 2 crystal oscillator inputs from the board.
+      HXT is a 24 MHz crystal feeding the internal PLLs. LXT is a 32.768
+      kHz crystal, for RTC and low power operations.
+
+  clock-names:
+    minItems: 1
+    items:
+      - const: hxt
+      - const: lxt
 
   nuvoton,pll-mode:
     description:
@@ -58,6 +69,7 @@ examples:
         compatible = "nuvoton,ma35d1-clk";
         reg = <0x40460200 0x100>;
         #clock-cells = <1>;
-        clocks = <&clk_hxt>;
+        clocks = <&clk_hxt>, <&clk_lxt>;
+        clock-names = "hxt", "lxt";
     };
 ...

-- 
2.55.0