[RFC PATCH 05/10] dt-bindings: pwm: Add bindings for PWM function in Netronix EC

["Jonathan Neuschäfer" <j.neuschaefer@gmx.net>]

The Netronix embedded controller as found in Kobo Aura and Tolino Shine
supports one PWM channel, which is used to control the frontlight
brightness on these devices.

Known problems:
- `make dt_binding_check` shows the following warnings:
  Documentation/devicetree/bindings/mfd/netronix,ntxec.example.dts:49.17-42:
  Warning (pwms_property): /example-0/backlight:pwms: cell 2 is not a
  phandle reference
  Documentation/devicetree/bindings/mfd/netronix,ntxec.example.dts:49.17-42:
  Warning (pwms_property): /example-0/backlight:pwms: Could not get
  phandle node for (cell 2)

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
---
 .../bindings/mfd/netronix,ntxec.yaml          | 13 ++++++++
 .../bindings/pwm/netronix,ntxec-pwm.yaml      | 33 +++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/netronix,ntxec-pwm.yaml

diff --git a/Documentation/devicetree/bindings/mfd/netronix,ntxec.yaml b/Documentation/devicetree/bindings/mfd/netronix,ntxec.yaml
index 596df460f98eb..6562c41c5a9a9 100644
--- a/Documentation/devicetree/bindings/mfd/netronix,ntxec.yaml
+++ b/Documentation/devicetree/bindings/mfd/netronix,ntxec.yaml
@@ -31,6 +31,9 @@ properties:
     description:
       The EC can signal interrupts via a GPIO line

+  pwm:
+    $ref: ../pwm/netronix,ntxec-pwm.yaml
+
 required:
   - compatible
   - reg
@@ -53,5 +56,15 @@ examples:
                     interrupts = <11 IRQ_TYPE_EDGE_FALLING>;
                     interrupt-controller;
                     #interrupt-cells = <1>;
+
+                    ec_pwm: pwm {
+                            compatible = "netronix,ntxec-pwm";
+                            #pwm-cells = <1>;
+                    };
             };
     };
+
+    backlight {
+            compatible = "pwm-backlight";
+            pwms = <&ec_pwm 0 50000>;
+    };
diff --git a/Documentation/devicetree/bindings/pwm/netronix,ntxec-pwm.yaml b/Documentation/devicetree/bindings/pwm/netronix,ntxec-pwm.yaml
new file mode 100644
index 0000000000000..1dc1b1aba081c
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/netronix,ntxec-pwm.yaml
@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/netronix,ntxec-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: PWM functionality in Netronix embedded controller
+
+maintainers:
+  - Jonathan Neuschäfer <j.neuschaefer@gmx.net>
+
+description: |
+  See also Documentation/devicetree/bindings/mfd/netronix,ntxec.yaml
+
+  The Netronix EC contains PWM functionality, which is usually used to drive
+  the backlight LED.
+
+  The following PWM channels are supported:
+    - 0: The PWM channel controlled by registers 0xa1-0xa7
+
+allOf:
+  - $ref: pwm.yaml#
+
+properties:
+  compatible:
+    const: netronix,ntxec-pwm
+
+  "#pwm-cells":
+    const: 1
+
+required:
+  - compatible
+  - "#pwm-cells"
--
2.27.0