dt-bindings: pinctrl: convert nsp-gpio binding

The brcm,nsp-gpio-a compatible used by the NSP GPIO controller was only documented in the legacy text binding, so dtbs_check reported "failed to match any schema" for the gpio@20 node present in the bcm958625 and related broadcom boards.

Convert Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.txt to a YAML schema and drop the text binding. Keep the existing required and optional properties (reg, #gpio-cells, gpio-controller, ngpios, and the optional interrupt/gpio-ranges support), including the generic pinconf child nodes with pin bias and drive-strength.

Pin configuration nodes may be direct children of the controller or grouped under a "-pins" node; both forms are recognized, and each "-pins" node may group further pin configuration children. Child nodes named "-hog" are supported as GPIO hogs.

The generic pinconf and pinmux helper schemas end in "additionalProperties: true" and cannot close the node from an in-place applicator, so spell out the supported subset and set "additionalProperties: false" in the local pin configuration node schema. Without it misspelled or unsupported properties such as "bias-pullup" or "slew-rate" are silently accepted.

Controller children are matched with "anyOf" against the pin configuration node schema and against "not: { type: object }". The latter keeps non-node properties such as #pinctrl-cells or clocks from being forced through the pin configuration schema, while still rejecting pin configuration child nodes that do not look like one. A plain "additionalProperties: false" cannot be used here because it would also reject the directly nested pin configuration nodes.

Assisted-by LLM

Signed-off-by Rosen Penev <[email protected]>

---
v3: add additionalProperties
v2: don't drop gpio-hog

 .../bindings/pinctrl/brcm,nsp-gpio.txt        |  80 ----------
 .../bindings/pinctrl/brcm,nsp-gpio.yaml       | 144 ++++++++++++++++++
 2 files changed, 144 insertions(+), 80 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.txt
 create mode 100644 Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.yaml

Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.yaml new file +91 -0

new file mode 100644
index 000000000000..e5144da1bf57
@@ -0,0 +1,144 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pinctrl/brcm,nsp-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom Northstar Plus (NSP) GPIO/PINCONF Controller
+
+maintainers:
+  - Ray Jui <[email protected]>
+  - Scott Branden <[email protected]>
+
+description: |
+  The chipCommonA GPIO block also provides generic pin configuration for the
+  pins it controls: bias, pull up/down and drive strength. Pin configuration
+  child nodes may be direct children of the controller, or grouped under a
+  '-pins' node. In both cases the pin configuration nodes are referenced by
+  the consuming device through the standard pinctrl-0/pinctrl-names
+  properties. Child nodes named '*-hog' are treated as GPIO hogs.
+
+properties:
+  compatible:
+    const: brcm,nsp-gpio-a
+
+  reg:
+    items:
+      - description: GPIO base registers
+      - description: IO control registers
+
+  "#gpio-cells":
+    const: 2
+    description: |
+      The first cell is the GPIO pin number (within the controller's pin
+      space) and the second cell is used for the following:
+      bit[0]: polarity (0 for active high and 1 for active low)
+
+  gpio-controller: true
+
+  ngpios:
+    description: Number of GPIOs supported (58x25 supports 32 and 58x23 supports 24)
+    maximum: 32
+
+  interrupts:
+    maxItems: 1
+
+  "#interrupt-cells":
+    const: 2
+
+  interrupt-controller: true
+
+  gpio-ranges: true
+
+required:
+  - compatible
+  - reg
+  - "#gpio-cells"
+  - gpio-controller
+  - ngpios
+
+$defs:
+  nsp-gpio-pinconf:
+    type: object
+    allOf:
+      - $ref: pincfg-node.yaml#
+      - $ref: pinmux-node.yaml#
+
+    properties:
+      pins:
+        $ref: /schemas/types.yaml#/definitions/string-array
+        items:
+          pattern: '^gpio-'
+
+      bias-disable: true
+      bias-pull-up: true
+      bias-pull-down: true
+
+      drive-strength:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [ 2, 4, 6, 8, 10, 12, 14, 16 ]
+
+    required:
+      - pins
+
+    additionalProperties: false
+
+patternProperties:
+  '-pins$':
+    oneOf:
+      - $ref: '#/$defs/nsp-gpio-pinconf'
+      - type: object
+        additionalProperties: