linux-kernel - [PATCH v3] dt-bindings: access-controllers: add controller configuration property

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Message-ID: <20250523-access-controllers-conf-v3-1-4382e69819cf@foss.st.com>
Date: Fri, 23 May 2025 16:08:10 +0200
From: Gatien Chevallier <gatien.chevallier@...s.st.com>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Oleksii Moisieiev
	<oleksii_moisieiev@...m.com>
CC: <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <alvinga@...estech.com>,
        Gatien Chevallier <gatien.chevallier@...s.st.com>
Subject: [PATCH v3] dt-bindings: access-controllers: add controller
 configuration property

Add a pattern property to allow a device to request an alternate
access rights configuration to one or more access controllers.
It allows run-time controller reconfiguration of access rights
to an authorized entity as used in OP-TEE OS [1].

Link: https://github.com/OP-TEE/optee_os/pull/6946 [1]
Signed-off-by: Gatien Chevallier <gatien.chevallier@...s.st.com>
---
v2->v3:
	-Precise that it the pattern property targets an access
	 rights configuration update
---
 .../access-controllers/access-controllers.yaml     | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml b/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml
index 99e2865f0e46a0600ebbba3bc5771dc63d578c8b..fe9d28d418cdef14a8ffa988ff6edc7a169b5361 100644
--- a/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml
+++ b/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml
@@ -45,6 +45,12 @@ properties:
       Can be any value as specified by device tree binding documentation
       of a particular provider. The node is an access controller.
 
+  "#access-conf-cells":
+    description:
+      Number of cells in an *(?<=)-access-conf$ specifier;
+      Can be any value as specified by device tree binding documentation
+      of a particular provider. The node is an access controller.
+
   access-controller-names:
     $ref: /schemas/types.yaml#/definitions/string-array
     description:
@@ -58,6 +64,16 @@ properties:
       A list of access controller specifiers, as defined by the
       bindings of the access-controllers provider.
 
+patternProperties:
+  ".*(?<=)-access-conf$":
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description:
+      An access controller configuration contains a list of inseparable entries.
+      A configuration may reference multiple access controllers. Therefore, each
+      entry content may vary accordingly to the access controller
+      "#access-conf-cells" value. A consumer will use this property to be able
+      to dynamically query for an access rights configuration update.
+
 additionalProperties: true
 
 examples:
@@ -65,6 +81,7 @@ examples:
     clock_controller: access-controllers@...00 {
         reg = <0x50000 0x400>;
         #access-controller-cells = <2>;
+        #access-conf-cells = <2>;
     };
 
     bus_controller: bus@...00 {
@@ -73,6 +90,7 @@ examples:
         #size-cells = <1>;
         ranges;
         #access-controller-cells = <3>;
+        #access-conf-cells = <2>;
 
         uart4: serial@...00 {
             reg = <0x60100 0x400>;
@@ -81,4 +99,17 @@ examples:
                                  <&bus_controller 1 3 5>;
             access-controller-names = "clock", "bus";
         };
+
+        uart5: serial@...00 {
+          reg = <0x60200 0x400>;
+          clocks = <&clk_serial2>;
+          access-controllers = <&bus_controller 0 0 0>, <&bus_controller 1 0 0>,
+                               <&clock_controller 2 3>;
+          default-access-conf = <&bus_controller 0 10>,
+                                <&bus_controller 1 10>,
+                                <&clock_controller 0 0>;
+          shared-access-conf = <&bus_controller 0 256>,
+                               <&bus_controller 1 256>,
+                               <&clock_controller 0 256>;
+        };
     };

---
base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
change-id: 20250523-access-controllers-conf-ff51551b953b

Best regards,
-- 
Gatien Chevallier <gatien.chevallier@...s.st.com>