[PATCH v5] spi: dt-bindings: Document the IBM FSI-attached SPI controller

[Eddie James <eajames@xxxxxxxxxxxxx>]

IBM Power processors have a SPI controller that can be accessed
over FSI from a service processor. Document it.

Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
---
This patch was previously included in https://lore.kernel.org/all/20240429210131.373487-1-eajames@xxxxxxxxxxxxx/

No changes since v3.

Changes since v2:
 - Change name from ibm,p10-spi to ibm,spi-fsi for two reasons. One, this
   matches the I2C controller binding (ibm,i2c-fsi), and two, this binding
   is specifically for the FSI-attached SPI controllers on the P10 but
   accessed from the service processor. P10 SPI controllers accessed from
   the P10 would have different bindings.
 - Fix warnings by using generic FSI parent node
 - Fix prefix

 .../devicetree/bindings/spi/ibm,spi-fsi.yaml  | 55 +++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/ibm,spi-fsi.yaml

diff --git a/Documentation/devicetree/bindings/spi/ibm,spi-fsi.yaml b/Documentation/devicetree/bindings/spi/ibm,spi-fsi.yaml
new file mode 100644
index 0000000000000..d7fec4c3a8016
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/ibm,spi-fsi.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/ibm,spi-fsi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: IBM FSI-attached SPI Controller
+
+maintainers:
+  - Eddie James <eajames@xxxxxxxxxxxxx>
+
+description:
+  A SPI controller found on IBM Power processors, accessed over FSI from a
+  service processor. This node will always be a child node of an ibm,fsi2spi
+  node.
+
+properties:
+  compatible:
+    enum:
+      - ibm,spi-fsi
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - $ref: spi-controller.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    fsi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        spi@0 {
+            compatible = "ibm,spi-fsi";
+            reg = <0>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            eeprom@0 {
+                compatible = "atmel,at25";
+                reg = <0>;
+                size = <0x80000>;
+                address-width = <24>;
+                pagesize = <256>;
+                spi-max-frequency = <1000000>;
+            };
+        };
+    };
-- 
2.39.3