[PATCH v4] dt-bindings: arm: keystone: add boot_* mboxes to ti,sci

[Anshul Dalal <anshuld@ti.com>]

The bootloader on K3 devices makes use of mailboxes as per the ROM spec
which might be different than one's available to the kernel (firmware
spec).

Therefore, this patch adds the missing mailbox entries to the DT binding
if the matching compatible is ti,am654-sci to represent the mailboxes
exposed by the hardware during boot for the purpose of loading the
firmware.

Signed-off-by: Anshul Dalal <anshuld@ti.com>
---
Changes in v4:
- Make new boot_* mboxes conditional on ti,am654-sci compatible
- Link to v3: https://lore.kernel.org/r/20251112-k3_syscon_add_boot_mailboxes-v3-1-66155a4236dc@ti.com

Changes in v3:
- Drop [1/2] of the last patch series
- Update existing example with boot_* mailboxes instead of adding a new one
- Link to v2: https://lore.kernel.org/r/20251112-k3_syscon_add_boot_mailboxes-v2-0-aebc1e47b391@ti.com

Changes in v2:
- Remove maxItems entry
- Remove RFC tag from patch (added by mistake in v1)
- Document the new mailboxes in mboxes instead of mbox-names
- Provide example with all the mailboxes set
- Update commit title to have "ti,sci"
- Split into two patches
- Link to v1: https://lore.kernel.org/r/20251111-k3_syscon_add_boot_mailboxes-v1-1-529a27f21076@ti.com
---
 .../devicetree/bindings/arm/keystone/ti,sci.yaml   | 50 +++++++++++++++++++---
 1 file changed, 43 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml b/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
index 25a2b42105e5..d9eb2a81e539 100644
--- a/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
+++ b/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
@@ -51,15 +51,15 @@ properties:
     minItems: 1
 
   mbox-names:
+    minItems: 2
+    maxItems: 6
     description: |
       Specifies the mailboxes used to communicate with TI-SCI Controller
       made available from TI-SCI controller.
-    items:
-      - const: rx
-      - const: tx
 
   mboxes:
     minItems: 2
+    maxItems: 6
 
   ti,host-id:
     $ref: /schemas/types.yaml#/definitions/uint32
@@ -79,6 +79,42 @@ properties:
     type: object
     $ref: /schemas/reset/ti,sci-reset.yaml#
 
+if:
+  properties:
+    compatible:
+      contains:
+        const: ti,am654-sci
+then:
+  properties:
+    mbox-names:
+      minItems: 2
+      items:
+        - const: rx
+        - const: tx
+        - const: notify
+        - const: boot_rx
+        - const: boot_tx
+        - const: boot_notify
+    mboxes:
+      minItems: 2
+      items:
+        - description: RX thread
+        - description: TX thread
+        - description: Notify thread
+        - description: boot stage RX thread
+        - description: boot stage TX thread
+        - description: boot stage Notify thread
+else:
+  properties:
+    mbox-names:
+      items:
+        - const: rx
+        - const: tx
+    mboxes:
+      items:
+        - description: RX thread
+        - description: TX thread
+
 required:
   - compatible
   - mbox-names
@@ -99,11 +135,11 @@ examples:
 
   - |
     dmsc: system-controller@44083000 {
-      compatible = "ti,k2g-sci";
+      compatible = "ti,am654-sci";
       ti,host-id = <12>;
-      mbox-names = "rx", "tx";
-      mboxes = <&secure_proxy_main 11>,
-               <&secure_proxy_main 13>;
+      mbox-names = "rx", "tx", "notify", "boot_rx", "boot_tx";
+      mboxes= <&secure_proxy_mcu 6>, <&secure_proxy_mcu 8>,
+        <&secure_proxy_mcu 5>, <&secure_proxy_mcu 5>, <&secure_proxy_mcu 4>;
       reg-names = "debug_messages";
       reg = <0x44083000 0x1000>;
 

---
base-commit: 4427259cc7f7571a157fbc9b5011e1ef6fe0a4a8
change-id: 20251105-k3_syscon_add_boot_mailboxes-8452bdd98962

Best regards,
-- 
Anshul Dalal <anshuld@ti.com>