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.

The newly added mboxes are made optional by keeping minItems as 2 to
remain compliant with existing device-trees. The new 'notify' channel is
not supported on all SoCs and is therefore kept at last in the list.

Signed-off-by: Anshul Dalal <redacted>
---
Changes in v7:
- Removed ti,am642-sci compatible
- Keep examples unchanged
- Modify ti,am654-sci ordering to ensure compliance with SoCs without a notify channel
- Link to v6: https://lore.kernel.org/r/20251222-k3_syscon_add_boot_mailboxes-v6-1-b93ada9f1d47@ti.com (local)

Changes in v6:
- Added ti,am642-sci compatible to represent SoCs without a "notify" channel
- Added new examples instead of editing existing ones
- Link to v5: https://lore.kernel.org/r/20251215-k3_syscon_add_boot_mailboxes-v5-1-5a8fe567fd31@ti.com (local)

Changes in v5:
- Added commit description for the optional mailboxes
- Link to v4: https://lore.kernel.org/r/20251205-k3_syscon_add_boot_mailboxes-v4-1-8e216fb88941@ti.com (local)

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 (local)

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 (local)

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 (local)
---
 .../devicetree/bindings/arm/keystone/ti,sci.yaml   | 42 ++++++++++++++++++++--
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml b/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
index 25a2b42105e5..e3f3de0192aa 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: boot_rx
+        - const: boot_tx
+        - const: boot_notify
+        - const: notify
+    mboxes:
+      minItems: 2
+      items:
+        - description: RX thread
+        - description: TX thread
+        - description: boot stage RX thread
+        - description: boot stage TX thread
+        - description: boot stage Notify thread
+        - description: Notify thread
+else:
+  properties:
+    mbox-names:
+      items:
+        - const: rx
+        - const: tx
+    mboxes:
+      items:
+        - description: RX thread
+        - description: TX thread
+
 required:
   - compatible
   - mbox-names

---
base-commit: f96074c6d01d8a5e9e2fccd0bba5f2ed654c1f2d
change-id: 20251105-k3_syscon_add_boot_mailboxes-8452bdd98962

Best regards,
-- 
Anshul Dalal [off-list ref]