[PATCH V4 1/2] dt-bindings: mailbox: Document qcom,ipq5424-tmel

[Sricharan R]

From: Sricharan Ramabadhran <quic_srichara@xxxxxxxxxxx>

TMEL(Trust Management Engine Lite) subsystem provides different kinds of
services like secureboot, remote image authentication, key management,
crypto, OEM provisioning etc.

The QMP mailbox is the primary means of communication between TMEL SS and
other subsystem on the SoC. A dedicated pair of inbound and outbound
mailboxes is implemented for each subsystem/external execution environment
which needs to communicate with TMEL for security services. The inbound
mailboxes are used to send IPC requests to TMEL, which are then processed
by TMEL firmware and accordingly the responses are sent back via outbound
mailboxes.

It is an IPC transport protocol which is light weight and supports a subset
of API's. It handles link initialization, negotiation, establishment and
communication across client(CPU/BTSS/AUDIOSS) and server(TMEL SS).

   -----------------------------------------------       ---------------------------------------------------
  |                                              |       |                                                 |
  |                 SOC  CLIENT                  | SOC   |                TMEL  SS                         |
  |                                              | AHB   |                                                 |
  |     ----------    ---------   ---------      |       | ------    -------     --------    ------------  |
  |     |        |    |       |   |       |      | WO    | |     | R |     |     |      |    |SERVICES   | |
  |     | CPU    |<-->| TMEL  |<->|       |------------->| | IN  |-->|     |     | TMEL |    |--------   | |
  |     |        |    | COM   |   | QMP   |      | RO    | |     | W | QMP |<--->| COM  |<-->| a) ATTEST | |
  |     |        |    |       |   |       |<-------------| | OUT |<--|     |     |      |    | b) CRYPTO | |
  |     |        |    |       |   |       |      |       | |     |   |     |     |      |    | .. more   | |
  |     ---------     ---------   ---------      |       | ------    -------     -------     ------------  |
  |                                              |       |                                                 |
   -----------------------------------------------       --------------------------------------------------

This binding describes the component responsible for communication between
the TMEL subsystem and the TMEL client (CPU/BTSS/AUDIOSS),
used for security services like secure image authentication, enable/disable
efuses, crypto services. Each client in the SoC has its own block of message
RAM and IRQ for communication with the TMEL SS.

Signed-off-by: Sricharan Ramabadhran <quic_srichara@xxxxxxxxxxx>
---
[v4]
	Fixed TMEL naming and added expansion
        Fixed wrappings for 80 columns

[V3]
        Fixed wrappings.
        Made mailbox-cells as a required property and changed value to '1'.
        Fixed to use compatible as filename.
        Renamed compatible as per Krzystof's comments.
        Dropped unused label.

[V2]
        Added HW description as per comments.
        Removed the fallback compatible.
        Fixed naming convention to TME-L in all places.
        Fixed indendation for example.
        Removed the 'description' for some items.

[V1]
	RFC Post.

 .../bindings/mailbox/qcom,ipq5424-tmel.yaml   | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/qcom,ipq5424-tmel.yaml

diff --git a/Documentation/devicetree/bindings/mailbox/qcom,ipq5424-tmel.yaml b/Documentation/devicetree/bindings/mailbox/qcom,ipq5424-tmel.yaml
new file mode 100644
index 000000000000..5bdeab166a1f
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/qcom,ipq5424-tmel.yaml
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mailbox/qcom,ipq5424-tmel.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm TMEL IPCC channel
+
+maintainers:
+  - Sricharan Ramabadhran <quic_srichara@xxxxxxxxxxx>
+
+description:
+  TMEL(Trust Management Engine Lite) SS provides different kinds of services
+  like secureboot, remote image authentication, key management, crypto, OEM
+  provisioning etc.
+
+  The QMP mailbox is the primary means of communication between TMEL SS and
+  other subsystem on the SoC. A dedicated pair of inbound and outbound mailbox
+  is implemented for each subsystem/external execution environment which needs
+  to communicate with TMEL for security services. The inbound mailboxes are used
+  to send IPC requests to TMEL, which are then processed by TMEL firmware and
+  accordingly the responses are sent back via outbound mailboxes.
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - qcom,ipq5424-tmel
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  mboxes:
+    maxItems: 1
+
+  "#mbox-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - mboxes
+  - "#mbox-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    mailbox@32090000 {
+        compatible = "qcom,ipq5424-tmel";
+        reg = <0x32090000 0x2000>;
+        interrupts = <GIC_SPI 126 IRQ_TYPE_EDGE_RISING>;
+        mboxes = <&apcs_glb 20>;
+        #mbox-cells = <1>;
+    };
-- 
2.34.1