[PATCH v2 1/2] dt-bindings: memory: document Renesas RPC-IF bindings

[Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>]

Renesas Reduced Pin Count Interface (RPC-IF) allows a SPI flash or
HyperFlash connected to the SoC to be accessed via the external address
space read mode or the manual mode.

Document the device tree bindings for the Renesas RPC-IF found in the R-Car
gen3 SoCs.

Based on the original patch by Mason Yang <masonccyang@xxxxxxxxxxx>.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>

---
Changes in version 2:
- rewrote the bindings in YAML.

 Documentation/devicetree/bindings/memory-controllers/renesas,rpc-if.yaml |   88 ++++++++++
 1 file changed, 88 insertions(+)

Index: linux/Documentation/devicetree/bindings/memory-controllers/renesas,rpc-if.yaml
===================================================================
--- /dev/null
+++ linux/Documentation/devicetree/bindings/memory-controllers/renesas,rpc-if.yaml
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: (GPL-2.0)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/memory-controllers/renesas,rpc-if.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas Reduced Pin Count Interface (RPC-IF)
+
+maintainers:
+  - Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
+
+description: |
+  Renesas RPC-IF allows a SPI flash or HyperFlash connected to the SoC to
+  be accessed via the external address space read mode or the manual mode.
+
+  The flash chip itself should be represented by a subnode of the RPC-IF node.
+  The flash interface is selected based on the "compatible" property of this
+  subnode:
+  - if it contains "jedec,spi-nor", then SPI is used;
+  - if it contains "cfi-flash", then HyperFlash is used.
+
+allOf:
+  - $ref: "/schemas/spi/spi-controller.yaml#"
+
+properties:
+  compatible:
+    items:
+      - enum:
+        renesas,r8a77980-rpc-if # device is a part of R8A77980 SoC
+	renesas,r8a77995-rpc-if # device is a part of R8A77995 SoC
+      - enum:
+        renesas,rcar-gen3-rpc-if # a generic R-Car gen3 device
+
+  reg:
+    items:
+       - description: RPC-IF registers
+       - description: direct mapping read mode area
+       - description: write buffer area
+
+  reg-names:
+    items:
+      - const: regs
+      - const: dirmap
+      - const: wbuf
+
+  clocks:
+    maxItems: 1
+
+  power-domains:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+patternProperties:
+  "^.*@[0-9a-f]+$":
+    type: object
+    properties:
+      compatible:
+        oneOf:
+          - const: cfi-flash
+          - const: jedec,spi-nor
+
+examples:
+  - |
+    #include <dt-bindings/clock/renesas-cpg-mssr.h>
+    #include <dt-bindings/power/r8a77995-sysc.h>
+
+    spi@ee200000 {
+      compatible = "renesas,r8a77995-rpc-if", "renesas,rcar-gen3-rpc-if";
+      reg = <0 0xee200000 0 0x200>,
+            <0 0x08000000 0 0x4000000>,
+            <0 0xee208000 0 0x100>;
+      reg-names = "regs", "dirmap", "wbuf";
+      clocks = <&cpg CPG_MOD 917>;
+      power-domains = <&sysc R8A77995_PD_ALWAYS_ON>;
+      resets = <&cpg 917>;
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      flash@0 {
+        compatible = "jedec,spi-nor";
+        reg = <0>;
+        spi-max-frequency = <40000000>;
+        spi-tx-bus-width = <1>;
+        spi-rx-bus-width = <1>;
+      };
+    };