dt-bindings: fpga: altr,fpga-passive-serial: Convert to yaml

Convert the Altera Passive Serial SPI FPGA Manager binding
from text file to yaml format to allow devicetree validation.

Signed-off-by: Fabio Estevam <[email protected]>
Reviewed-by: Conor Dooley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rob Herring (Arm) <[email protected]>

Author: Fabio Estevam

Documentation/devicetree/bindings/fpga/altera-passive-serial.txt

@@ -0,0 +1,74 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/fpga/altr,fpga-passive-serial.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Altera Passive Serial SPI FPGA Manager
+
+maintainers:
+  - Fabio Estevam <[email protected]>
+
+description: |
+  Altera FPGAs support a method of loading the bitstream over what is
+  referred to as "passive serial".
+  The passive serial link is not technically SPI, and might require extra
+  circuits in order to play nicely with other SPI slaves on the same bus.
+
+  See https://www.altera.com/literature/hb/cyc/cyc_c51013.pdf
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - altr,fpga-passive-serial
+      - altr,fpga-arria10-passive-serial
+
+  spi-max-frequency:
+    maximum: 20000000
+
+  reg:
+    maxItems: 1
+
+  nconfig-gpios:
+    description:
+      Config pin (referred to as nCONFIG in the manual).
+    maxItems: 1
+
+  nstat-gpios:
+    description:
+      Status pin (referred to as nSTATUS in the manual).
+    maxItems: 1
+
+  confd-gpios:
+    description:
+      confd pin (referred to as CONF_DONE in the manual)
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - nconfig-gpios
+  - nstat-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      fpga@0 {
+        compatible = "altr,fpga-passive-serial";
+        reg = <0>;
+        nconfig-gpios = <&gpio4 18 GPIO_ACTIVE_LOW>;
+        nstat-gpios = <&gpio4 19 GPIO_ACTIVE_LOW>;
+        confd-gpios = <&gpio1 6 GPIO_ACTIVE_HIGH>;
+      };
+    };
+...