linux-kernel - [PATCH v2 04/10] dt-bindings: pwm: Add bindings for PWM function in Netronix EC

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Date:   Sat,  5 Sep 2020 15:32:24 +0200
From:   Jonathan Neuschäfer <j.neuschaefer@....net>
To:     linux-kernel@...r.kernel.org
Cc:     Lee Jones <lee.jones@...aro.org>, Rob Herring <robh+dt@...nel.org>,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Heiko Stuebner <heiko.stuebner@...obroma-systems.com>,
        Stephan Gerhold <stephan@...hold.net>,
        Lubomir Rintel <lkundrak@...sk>,
        Mark Brown <broonie@...nel.org>, allen <allen.chen@....com.tw>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        devicetree@...r.kernel.org, linux-pwm@...r.kernel.org,
        linux-rtc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Heiko Stuebner <heiko@...ech.de>,
        Josua Mayer <josua.mayer@....eu>,
        Andreas Kemnade <andreas@...nade.info>,
        Arnd Bergmann <arnd@...db.de>, Daniel Palmer <daniel@...f.com>
Subject: [PATCH v2 04/10] dt-bindings: pwm: Add bindings for PWM function in Netronix EC

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.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@....net>
---

v2:
- Add plaintext binding to patch description, for comparison
- Fix pwm-cells property (should be 2, not 1)
- Add dummy regulator to example, because the pwm-backlight binding requires a
  power supply


For reference, here is the binding in text form:


  PWM functionality in Netronix Embedded Controller

  Required properties:
  - compatible: should be "netronix,ntxec-pwm"
  - #pwm-cells: should be 2.

  Available PWM channels:
  - 0: The PWM channel controlled by registers 0xa1-0xa7

  Example:

  	embedded-controller@43 {
  		compatible = "netronix,ntxec";
  		...

  		ec_pwm: pwm {
  			compatible = "netronix,ntxec-pwm";
  			#pwm-cells = <1>;
  		};
  	};

  	...

  	backlight {
  		compatible = "pwm-backlight";
  		pwms = <&ec_pwm 0 50000>;
  	};
---
 .../bindings/mfd/netronix,ntxec.yaml          | 19 +++++++++++
 .../bindings/pwm/netronix,ntxec-pwm.yaml      | 33 +++++++++++++++++++
 2 files changed, 52 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..73c873dda3e70 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:
+    $ref: ../pwm/netronix,ntxec-pwm.yaml
+
 required:
   - compatible
   - reg
@@ -53,5 +56,21 @@ examples:
                     interrupts = <11 IRQ_TYPE_EDGE_FALLING>;
                     interrupt-controller;
                     #interrupt-cells = <1>;
+
+                    ec_pwm: pwm {
+                            compatible = "netronix,ntxec-pwm";
+                            #pwm-cells = <2>;
+                    };
             };
     };
+
+    backlight {
+            compatible = "pwm-backlight";
+            pwms = <&ec_pwm 0 50000>;
+            power-supply = <&backlight_regulator>;
+    };
+
+    backlight_regulator: regulator-dummy {
+            compatible = "regulator-fixed";
+            regulator-name = "backlight";
+    };
diff --git a/Documentation/devicetree/bindings/pwm/netronix,ntxec-pwm.yaml b/Documentation/devicetree/bindings/pwm/netronix,ntxec-pwm.yaml
new file mode 100644
index 0000000000000..0c9d2801b8de1
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/netronix,ntxec-pwm.yaml
@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$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@....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: 2
+
+required:
+  - compatible
+  - "#pwm-cells"
--
2.28.0