[PATCH v4 1/7] dt-bindings: arm: fsl: add se-fw binding doc

[Pankaj Gupta]

The NXP's i.MX EdgeLock Enclave, a HW IP creating an embedded
secure enclave within the SoC boundary to enable features like
- HSM
- SHE
- V2X

Communicates via message unit with linux kernel. This driver
is enables communication ensuring well defined message sequence
protocol between Application Core and enclave's firmware.

Driver configures multiple misc-device on the MU, for multiple
user-space applications can communicate on single MU.

It exists on some i.MX processors. e.g. i.MX8ULP, i.MX93 etc.

Signed-off-by: Pankaj Gupta <pankaj.gupta at nxp.com>
---
 .../bindings/arm/freescale/fsl,se-fw.yaml     | 121 ++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml

diff --git a/Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml b/Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml
new file mode 100644
index 000000000000..7567da0b4c21
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml
@@ -0,0 +1,121 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/freescale/fsl,se-fw.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP i.MX EdgeLock Enclave Firmware (ELEFW)
+
+maintainers:
+  - Pankaj Gupta <pankaj.gupta at nxp.com>
+
+description: |
+
+  The NXP's i.MX EdgeLock Enclave, a HW IP creating an embedded
+  secure enclave within the SoC boundary to enable features like
+  - HSM
+  - SHE
+  - V2X
+
+  It uses message unit to communicate and coordinate to pass messages
+  (e.g., data,  status and control) through its interfaces.
+
+  This driver configures multiple misc-devices on the MU, to exchange
+  messages from User-space application and NXP's Edgelocke Enclave firmware.
+  The driver ensures that the messages must follow the following protocol
+  defined.
+
+                                     Non-Secure           +   Secure
+                                                          |
+                                                          |
+                   +---------+      +-------------+       |
+                   | ele_mu.c+<---->+imx-mailbox.c|       |
+                   |         |      |  mailbox.c  +<-->+------+    +------+
+                   +---+-----+      +-------------+    | MU X +<-->+ ELE |
+                       |                               +------+    +------+
+                       +----------------+                 |
+                       |                |                 |
+                       v                v                 |
+                   logical           logical              |
+                   receiver          waiter               |
+                      +                 +                 |
+                      |                 |                 |
+                      |                 |                 |
+                      |            +----+------+          |
+                      |            |           |          |
+                      |            |           |          |
+               device_ctx     device_ctx     device_ctx   |
+                                                          |
+                 User 0        User 1       User Y        |
+                 +------+      +------+     +------+      |
+                 |misc.c|      |misc.c|     |misc.c|      |
+  kernel space   +------+      +------+     +------+      |
+                                                          |
+  +------------------------------------------------------ |
+                     |             |           |          |
+  userspace     /dev/ele_muXch0    |           |          |
+                           /dev/ele_muXch1     |          |
+                                         /dev/ele_muXchY  |
+                                                          |
+
+  When a user sends a command to the ELE, it registers its device_ctx as
+  waiter of a response from ELE.
+
+  A user can be registered as receiver of command from the ELE.
+  Create char devices in /dev as channels of the form /dev/ele_muXchY with X
+  the id of the driver and Y for each users. It allows to send and receive
+  messages to the NXP EdgeLock Enclave IP on NXP SoC, where current possible
+  value, i.e., supported SoC(s) are imx8ulp, imx93.
+
+properties:
+  compatible:
+    enum:
+      - fsl,imx-ele
+      - fsl,imx93-ele
+
+  mboxes:
+    description:
+      A list of phandles of TX MU channels followed by a list of phandles of
+      RX MU channels. The number of expected tx and rx channels is 1 TX, and
+      1 RX channels. All MU channels must be within the same MU instance.
+      Cross instances are not allowed. The MU instance to be used is S4MUAP
+      for imx8ulp & imx93. Users need to ensure that used MU instance does not
+      conflict with other execution environments.
+    items:
+      - description: TX0 MU channel
+      - description: RX0 MU channel
+
+  mbox-names:
+    items:
+      - const: tx
+      - const: rx
+
+  fsl,mu-did:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Owner of message-unit, is identified via Domain ID or did.
+
+  fsl,mu-id:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Identifier to the message-unit among the multiple message-unit that exists on SoC.
+      It is used to create the channels, default to 2
+
+
+required:
+  - compatible
+  - mboxes
+  - mbox-names
+
+additionalProperties: false
+
+examples:
+  - |
+    ele_mu: ele_mu {
+      compatible = "fsl,imx93-ele";
+      mbox-names = "tx", "rx";
+      mboxes = <&s4muap 2 0
+                &s4muap 3 0>;
+      fsl,mu-did = <1>;
+      fsl,mu-id = <1>;
+    };
-- 
2.34.1