spi: dt-binding: document Microchip CoreSPI

Add device tree bindings for Microchip's CoreSPI controller.

CoreSPI is a "soft" IP core intended for FPGA implementations. Its
configurations are set in Libero. These properties represent
non-discoverable configurations determined by Verilog parameters to the
IP.

Signed-off-by: Prajna Rajendra Kumar <prajna.rajendrakumar@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20251114104545.284765-3-prajna.rajendrakumar@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: prajnark

Documentation/devicetree/bindings/spi/microchip,mpfs-spi.yaml

@@ -21,11 +21,13 @@ properties:
               - microchip,mpfs-qspi
               - microchip,pic64gx-qspi
           - const: microchip,coreqspi-rtl-v2
-      - const: microchip,coreqspi-rtl-v2 # FPGA QSPI
+      - enum:
+          - microchip,coreqspi-rtl-v2 # FPGA QSPI
+          - microchip,corespi-rtl-v5 # FPGA CoreSPI
+          - microchip,mpfs-spi
       - items:
           - const: microchip,pic64gx-spi
           - const: microchip,mpfs-spi
-      - const: microchip,mpfs-spi
 
   reg:
     maxItems: 1
@@ -39,6 +41,45 @@ properties:
   clocks:
     maxItems: 1
 
+  microchip,apb-datawidth:
+    description: APB bus data width in bits.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [8, 16, 32]
+    default: 8
+
+  microchip,frame-size:
+    description: |
+      Number of bits per SPI frame, as configured in Libero.
+      In Motorola and TI modes, this corresponds directly
+      to the requested frame size. For NSC mode this is set
+      to 9 + the required data frame size.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 4
+    maximum: 32
+    default: 8
+
+  microchip,protocol-configuration:
+    description: CoreSPI protocol selection. Determines operating mode
+    $ref: /schemas/types.yaml#/definitions/string
+    enum:
+      - motorola
+      - ti
+      - nsc
+    default: motorola
+
+  microchip,motorola-mode:
+    description: Motorola SPI mode selection
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [0, 1, 2, 3]
+    default: 3
+
+  microchip,ssel-active:
+    description: |
+      Keep SSEL asserted between frames when using the Motorola protocol.
+      When present, the controller keeps SSEL active across contiguous
+      transfers and deasserts only when the overall transfer completes.
+    type: boolean
+
 required:
   - compatible
   - reg
@@ -71,6 +112,31 @@ allOf:
         num-cs:
           maximum: 1
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: microchip,corespi-rtl-v5
+    then:
+      properties:
+        num-cs:
+          minimum: 1
+          maximum: 8
+          default: 8
+
+        fifo-depth:
+          minimum: 1
+          maximum: 32
+          default: 4
+
+    else:
+      properties:
+        microchip,apb-datawidth: false
+        microchip,frame-size: false
+        microchip,protocol-configuration: false
+        microchip,motorola-mode: false
+        microchip,ssel-active: false
+
 unevaluatedProperties: false
 
 examples: