[RFC PATCH 1/3] dt-bindings: watchdog: arm-smc-wdt: allow a list of SMC ids

[Mateusz Nowicki <mateusz.nowicki@posteo.net>]

The SMC function id of the watchdog service is not discoverable and
differs between firmware versions for the same SoC. Let arm,smc-id hold
a list of ids that the driver tries in order, so a SoC dtsi can name
every id used by firmware for that SoC. A single id stays valid.

Signed-off-by: Mateusz Nowicki <mateusz.nowicki@posteo.net>
---
 .../devicetree/bindings/watchdog/arm-smc-wdt.yaml        | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/watchdog/arm-smc-wdt.yaml b/Documentation/devicetree/bindings/watchdog/arm-smc-wdt.yaml
index 8e9d0b7e8244..9844b23ef51c 100644
--- a/Documentation/devicetree/bindings/watchdog/arm-smc-wdt.yaml
+++ b/Documentation/devicetree/bindings/watchdog/arm-smc-wdt.yaml
@@ -18,9 +18,14 @@ properties:
       - arm,smc-wdt
 
   arm,smc-id:
-    $ref: /schemas/types.yaml#/definitions/uint32
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 1
+    maxItems: 4
     description: |
-      The ATF smc function id used by the firmware.
+      The ATF smc function id used by the firmware, or a list of ids for
+      firmware versions that use different ones. The ids are tried in order
+      until the firmware accepts the init call, so only ids that are known
+      to be this watchdog service on the platform belong in the list.
       Defaults to 0x82003D06 if unset.
 
 required:
-- 
2.56.0