Merge tag 'leds-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds

Pull LED updates from Pavel Machek:
 "Okay, so... this one is interesting. RGB LEDs are very common, and we
  need to have some kind of support for them. Multicolor is for
  arbitrary set of LEDs in one package, RGB is for LEDs that can produce
  full range of colors. We do not have real multicolor LED that is not
  RGB in the pipeline, so that one is disabled for now.

  You can expect this saga to continue with next pull requests"

* tag 'leds-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds: (37 commits)
  MAINTAINERS: Remove myself as LED subsystem maintainer
  leds: disallow /sys/class/leds/*:multi:* for now
  leds: add RGB color option, as that is different from multicolor.
  Make LEDS_LP55XX_COMMON depend on I2C to fix build errors:
  Documentation: ABI: leds-turris-omnia: document sysfs attribute
  leds: initial support for Turris Omnia LEDs
  dt-bindings: leds: add cznic,turris-omnia-leds binding
  leds: pattern trigger -- check pattern for validity
  leds: Replace HTTP links with HTTPS ones
  leds: trigger: add support for LED-private device triggers
  leds: lp5521: Add multicolor framework multicolor brightness support
  leds: lp5523: Update the lp5523 code to add multicolor brightness function
  leds: lp55xx: Add multicolor framework support to lp55xx
  leds: lp55xx: Convert LED class registration to devm_*
  dt-bindings: leds: Convert leds-lp55xx to yaml
  leds: multicolor: Introduce a multicolor class definition
  leds: Add multicolor ID to the color ID list
  dt: bindings: Add multicolor class dt bindings documention
  leds: lp5523: Fix various formatting issues in the code
  leds: lp55xx: Fix file permissions to use DEVICE_ATTR macros
  ...

11 files changed, 357 insertions, 238 deletions

diff --git a/Documentation/devicetree/bindings/leds/cznic,turris-omnia-leds.yaml b/Documentation/devicetree/bindings/leds/cznic,turris-omnia-leds.yaml
new file mode 100644
index 000000000000..24ad1446445e
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/cznic,turris-omnia-leds.yaml
@@ -0,0 +1,90 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/cznic,turris-omnia-leds.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: CZ.NIC's Turris Omnia LEDs driver
+
+maintainers:
+  - Marek Behún <marek.behun@nic.cz>
+
+description:
+  This module adds support for the RGB LEDs found on the front panel of the
+  Turris Omnia router. There are 12 RGB LEDs that are controlled by a
+  microcontroller that communicates via the I2C bus. Each LED is described
+  as a subnode of this I2C device.
+
+properties:
+  compatible:
+    const: cznic,turris-omnia-leds
+
+  reg:
+    description: I2C slave address of the microcontroller.
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^multi-led[0-9a-f]$":
+    type: object
+    allOf:
+      - $ref: leds-class-multicolor.yaml#
+    description:
+      This node represents one of the RGB LED devices on Turris Omnia.
+      No subnodes need to be added for subchannels since this controller only
+      supports RGB LEDs.
+
+    properties:
+      reg:
+        minimum: 0
+        maximum: 11
+        description:
+          This property identifies one of the LEDs on the front panel of the
+          Turris Omnia router.
+
+    required:
+      - reg
+
+additionalProperties: false
+
+examples:
+  - |
+
+    #include <dt-bindings/leds/common.h>
+
+    i2c0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        led-controller@2b {
+            compatible = "cznic,turris-omnia-leds";
+            reg = <0x2b>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            multi-led@0 {
+                /*
+                 * No subnodes are needed, this controller only supports RGB
+                 * LEDs.
+                 */
+                reg = <0>;
+                color = <LED_COLOR_ID_MULTI>;
+                function = LED_FUNCTION_POWER;
+                linux,default-trigger = "heartbeat";
+            };
+
+            multi-led@a {
+                reg = <0xa>;
+                color = <LED_COLOR_ID_MULTI>;
+                function = LED_FUNCTION_INDICATOR;
+                function-enumerator = <1>;
+            };
+        };
+    };
+
+...
diff --git a/Documentation/devicetree/bindings/leds/leds-class-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-class-multicolor.yaml
new file mode 100644
index 000000000000..b55e1f1308a4
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-class-multicolor.yaml
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/leds-class-multicolor.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Common properties for the multicolor LED class.
+
+maintainers:
+  - Dan Murphy <dmurphy@ti.com>
+
+description: |
+  Bindings for multi color LEDs show how to describe current outputs of
+  either integrated multi-color LED elements (like RGB, RGBW, RGBWA-UV
+  etc.) or standalone LEDs, to achieve logically grouped multi-color LED
+  modules. This is achieved by adding multi-led nodes layer to the
+  monochrome LED bindings.
+  The nodes and properties defined in this document are unique to the multicolor
+  LED class.  Common LED nodes and properties are inherited from the common.txt
+  within this documentation directory.
+
+patternProperties:
+  "^multi-led@([0-9a-f])$":
+    type: object
+    description: Represents the LEDs that are to be grouped.
+    properties:
+      color:
+        const: 8  # LED_COLOR_ID_MULTI
+        description: |
+          For multicolor LED support this property should be defined as
+          LED_COLOR_ID_MULTI which can be found in include/linux/leds/common.h.
+
+    $ref: "common.yaml#"
+
+    required:
+      - color
+...
diff --git a/Documentation/devicetree/bindings/leds/leds-lm3532.txt b/Documentation/devicetree/bindings/leds/leds-lm3532.txt
index 53793213dd52..097490a5ff91 100644
--- a/Documentation/devicetree/bindings/leds/leds-lm3532.txt
+++ b/Documentation/devicetree/bindings/leds/leds-lm3532.txt
@@ -102,4 +102,4 @@ led-controller@38 {
 };
 
 For more product information please see the links below:
-http://www.ti.com/product/LM3532
+https://www.ti.com/product/LM3532
diff --git a/Documentation/devicetree/bindings/leds/leds-lm3601x.txt b/Documentation/devicetree/bindings/leds/leds-lm3601x.txt
index 095dafb6ec7f..17e940025dc2 100644
--- a/Documentation/devicetree/bindings/leds/leds-lm3601x.txt
+++ b/Documentation/devicetree/bindings/leds/leds-lm3601x.txt
@@ -47,5 +47,5 @@ led-controller@64 {
 }
 
 For more product information please see the links below:
-http://www.ti.com/product/LM36010
-http://www.ti.com/product/LM36011
+https://www.ti.com/product/LM36010
+https://www.ti.com/product/LM36011
diff --git a/Documentation/devicetree/bindings/leds/leds-lm36274.txt b/Documentation/devicetree/bindings/leds/leds-lm36274.txt
index 39c230d59a4d..de6f4931fb31 100644
--- a/Documentation/devicetree/bindings/leds/leds-lm36274.txt
+++ b/Documentation/devicetree/bindings/leds/leds-lm36274.txt
@@ -82,4 +82,4 @@ lm36274@11 {
 };
 
 For more product information please see the link below:
-http://www.ti.com/lit/ds/symlink/lm36274.pdf
+https://www.ti.com/lit/ds/symlink/lm36274.pdf
diff --git a/Documentation/devicetree/bindings/leds/leds-lm3692x.txt b/Documentation/devicetree/bindings/leds/leds-lm3692x.txt
index 501468aa4d38..b1103d961d6c 100644
--- a/Documentation/devicetree/bindings/leds/leds-lm3692x.txt
+++ b/Documentation/devicetree/bindings/leds/leds-lm3692x.txt
@@ -62,4 +62,4 @@ led-controller@36 {
 }
 
 For more product information please see the link below:
-http://www.ti.com/lit/ds/snvsa29/snvsa29.pdf
+https://www.ti.com/lit/ds/snvsa29/snvsa29.pdf
diff --git a/Documentation/devicetree/bindings/leds/leds-lm3697.txt b/Documentation/devicetree/bindings/leds/leds-lm3697.txt
index 63992d732959..221b37b6049b 100644
--- a/Documentation/devicetree/bindings/leds/leds-lm3697.txt
+++ b/Documentation/devicetree/bindings/leds/leds-lm3697.txt
@@ -70,4 +70,4 @@ led-controller@36 {
 }
 
 For more product information please see the link below:
-http://www.ti.com/lit/ds/symlink/lm3697.pdf
+https://www.ti.com/lit/ds/symlink/lm3697.pdf
diff --git a/Documentation/devicetree/bindings/leds/leds-lp55xx.txt b/Documentation/devicetree/bindings/leds/leds-lp55xx.txt
deleted file mode 100644
index 1b66a413fb9d..000000000000
--- a/Documentation/devicetree/bindings/leds/leds-lp55xx.txt
+++ /dev/null
@@ -1,228 +0,0 @@
-Binding for TI/National Semiconductor LP55xx Led Drivers
-
-Required properties:
-- compatible: one of
-	national,lp5521
-	national,lp5523
-	ti,lp55231
-	ti,lp5562
-	ti,lp8501
-
-- reg: I2C slave address
-- clock-mode: Input clock mode, (0: automode, 1: internal, 2: external)
-
-Each child has own specific current settings
-- led-cur: Current setting at each led channel (mA x10, 0 if led is not connected)
-- max-cur: Maximun current at each led channel.
-
-Optional properties:
-- enable-gpio: GPIO attached to the chip's enable pin
-- label: Used for naming LEDs
-- pwr-sel: LP8501 specific property. Power selection for output channels.
-         0: D1~9 are connected to VDD
-         1: D1~6 with VDD, D7~9 with VOUT
-         2: D1~6 with VOUT, D7~9 with VDD
-         3: D1~9 are connected to VOUT
-
-Alternatively, each child can have a specific channel name and trigger:
-- chan-name (optional): name of channel
-- linux,default-trigger (optional): see
-  Documentation/devicetree/bindings/leds/common.txt
-
-example 1) LP5521
-3 LED channels, external clock used. Channel names are 'lp5521_pri:channel0',
-'lp5521_pri:channel1' and 'lp5521_pri:channel2', with a heartbeat trigger
-on channel 0.
-
-lp5521@32 {
-	compatible = "national,lp5521";
-	reg = <0x32>;
-	label = "lp5521_pri";
-	clock-mode = /bits/ 8 <2>;
-
-	chan0 {
-		led-cur = /bits/ 8 <0x2f>;
-		max-cur = /bits/ 8 <0x5f>;
-		linux,default-trigger = "heartbeat";
-	};
-
-	chan1 {
-		led-cur = /bits/ 8 <0x2f>;
-		max-cur = /bits/ 8 <0x5f>;
-	};
-
-	chan2 {
-		led-cur = /bits/ 8 <0x2f>;
-		max-cur = /bits/ 8 <0x5f>;
-	};
-};
-
-example 2) LP5523
-9 LED channels with specific name. Internal clock used.
-The I2C slave address is configurable with ASEL1 and ASEL0 pins.
-Available addresses are 32/33/34/35h.
-
-ASEL1    ASEL0    Address
--------------------------
- GND      GND       32h
- GND      VEN       33h
- VEN      GND       34h
- VEN      VEN       35h
-
-lp5523@32 {
-	compatible = "national,lp5523";
-	reg = <0x32>;
-	clock-mode = /bits/ 8 <1>;
-
-	chan0 {
-		chan-name = "d1";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan1 {
-		chan-name = "d2";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan2 {
-		chan-name = "d3";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan3 {
-		chan-name = "d4";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan4 {
-		chan-name = "d5";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan5 {
-		chan-name = "d6";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan6 {
-		chan-name = "d7";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan7 {
-		chan-name = "d8";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan8 {
-		chan-name = "d9";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-};
-
-example 3) LP5562
-4 channels are defined.
-
-lp5562@30 {
-	compatible = "ti,lp5562";
-	reg = <0x30>;
-	clock-mode = /bits/8 <2>;
-
-	chan0 {
-		chan-name = "R";
-		led-cur = /bits/ 8 <0x20>;
-		max-cur = /bits/ 8 <0x60>;
-	};
-
-	chan1 {
-		chan-name = "G";
-		led-cur = /bits/ 8 <0x20>;
-		max-cur = /bits/ 8 <0x60>;
-	};
-
-	chan2 {
-		chan-name = "B";
-		led-cur = /bits/ 8 <0x20>;
-		max-cur = /bits/ 8 <0x60>;
-	};
-
-	chan3 {
-		chan-name = "W";
-		led-cur = /bits/ 8 <0x20>;
-		max-cur = /bits/ 8 <0x60>;
-	};
-};
-
-example 4) LP8501
-9 channels are defined. The 'pwr-sel' is LP8501 specific property.
-Others are same as LP5523.
-
-lp8501@32 {
-	compatible = "ti,lp8501";
-	reg = <0x32>;
-	clock-mode = /bits/ 8 <2>;
-	pwr-sel = /bits/ 8 <3>;	/* D1~9 connected to VOUT */
-
-	chan0 {
-		chan-name = "d1";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan1 {
-		chan-name = "d2";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan2 {
-		chan-name = "d3";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan3 {
-		chan-name = "d4";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan4 {
-		chan-name = "d5";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan5 {
-		chan-name = "d6";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan6 {
-		chan-name = "d7";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan7 {
-		chan-name = "d8";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-
-	chan8 {
-		chan-name = "d9";
-		led-cur = /bits/ 8 <0x14>;
-		max-cur = /bits/ 8 <0x20>;
-	};
-};
diff --git a/Documentation/devicetree/bindings/leds/leds-lp55xx.yaml b/Documentation/devicetree/bindings/leds/leds-lp55xx.yaml
new file mode 100644
index 000000000000..b1bb3feb0f4d
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-lp55xx.yaml
@@ -0,0 +1,220 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/leds-lp55xx.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI/National Semiconductor LP55xx and LP8501 LED Drivers
+
+maintainers:
+  - Jacek Anaszewski <jacek.anaszewski@gmail.com>
+  - Pavel Machek <pavel@ucw.cz>
+
+description: |
+  Bindings for the TI/National Semiconductor LP55xx and LP8501 multi channel
+  LED Drivers.
+
+  For more product information please see the link below:
+    https://www.ti.com/lit/gpn/lp5521
+    https://www.ti.com/lit/gpn/lp5523
+    https://www.ti.com/lit/gpn/lp55231
+    https://www.ti.com/lit/gpn/lp5562
+    https://www.ti.com/lit/gpn/lp8501
+
+properties:
+  compatible:
+    enum:
+      - national,lp5521
+      - national,lp5523
+      - ti,lp55231
+      - ti,lp5562
+      - ti,lp8501
+
+  reg:
+    maxItems: 1
+    description: I2C slave address
+
+  clock-mode:
+    $ref: /schemas/types.yaml#definitions/uint8
+    description: |
+      Input clock mode
+    enum:
+      - 0 # automode
+      - 1 # internal
+      - 2 # external
+
+  enable-gpio:
+    maxItems: 1
+    description: |
+      GPIO attached to the chip's enable pin
+
+  pwr-sel:
+    $ref: /schemas/types.yaml#definitions/uint8
+    description: |
+      LP8501 specific property. Power selection for output channels.
+    enum:
+      - 0 # D1~9 are connected to VDD
+      - 1 # D1~6 with VDD, D7~9 with VOUT
+      - 2 # D1~6 with VOUT, D7~9 with VDD
+      - 3 # D1~9 are connected to VOUT
+
+patternProperties:
+  "(^led@[0-9a-f]$|led)":
+    type: object
+    $ref: common.yaml#
+    properties:
+      led-cur:
+        $ref: /schemas/types.yaml#definitions/uint8
+        description: |
+          Current setting at each LED channel (mA x10, 0 if LED is not connected)
+        minimum: 0
+        maximum: 255
+
+      max-cur:
+        $ref: /schemas/types.yaml#definitions/uint8
+        description: Maximun current at each LED channel.
+
+      reg:
+        description: |
+          Output channel for the LED.  This is zero based channel identifier and
+          the data sheet is a one based channel identifier.
+          reg value to output to LED output number
+        enum:
+          - 0 # LED output D1
+          - 1 # LED output D2
+          - 2 # LED output D3
+          - 3 # LED output D4
+          - 4 # LED output D5
+          - 5 # LED output D6
+          - 6 # LED output D7
+          - 7 # LED output D8
+          - 8 # LED output D9
+
+      chan-name:
+        $ref: /schemas/types.yaml#definitions/string
+        description: name of channel
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+   #include <dt-bindings/leds/common.h>
+
+   i2c {
+       #address-cells = <1>;
+       #size-cells = <0>;
+
+       led-controller@32 {
+           #address-cells = <1>;
+           #size-cells = <0>;
+           compatible = "ti,lp8501";
+           reg = <0x32>;
+           clock-mode = /bits/ 8 <2>;
+           pwr-sel = /bits/ 8 <3>;	/* D1~9 connected to VOUT */
+
+           led@0 {
+               reg = <0>;
+               chan-name = "d1";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@1 {
+               reg = <1>;
+               chan-name = "d2";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@2 {
+               reg = <2>;
+               chan-name = "d3";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@3 {
+               reg = <3>;
+               chan-name = "d4";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@4 {
+               reg = <4>;
+               chan-name = "d5";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@5 {
+               reg = <5>;
+               chan-name = "d6";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@6 {
+               reg = <6>;
+               chan-name = "d7";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@7 {
+               reg = <7>;
+               chan-name = "d8";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+
+           led@8 {
+               reg = <8>;
+               chan-name = "d9";
+               led-cur = /bits/ 8 <0x14>;
+               max-cur = /bits/ 8 <0x20>;
+           };
+        };
+
+       led-controller@33 {
+           #address-cells = <1>;
+           #size-cells = <0>;
+           compatible = "national,lp5523";
+           reg = <0x33>;
+           clock-mode = /bits/ 8 <0>;
+
+           multi-led@2 {
+               #address-cells = <1>;
+               #size-cells = <0>;
+               reg = <0x2>;
+               color = <LED_COLOR_ID_MULTI>;
+               function = LED_FUNCTION_STANDBY;
+               linux,default-trigger = "heartbeat";
+
+               led@0 {
+                   led-cur = /bits/ 8 <50>;
+                   max-cur = /bits/ 8 <100>;
+                   reg = <0x0>;
+                   color = <LED_COLOR_ID_GREEN>;
+               };
+
+               led@1 {
+                   led-cur = /bits/ 8 <50>;
+                   max-cur = /bits/ 8 <100>;
+                   reg = <0x1>;
+                   color = <LED_COLOR_ID_BLUE>;
+               };
+
+               led@6 {
+                   led-cur = /bits/ 8 <50>;
+                   max-cur = /bits/ 8 <100>;
+                   reg = <0x6>;
+                   color = <LED_COLOR_ID_RED>;
+               };
+            };
+        };
+    };
+
+...
diff --git a/Documentation/devicetree/bindings/leds/leds-lp8860.txt b/Documentation/devicetree/bindings/leds/leds-lp8860.txt
index 9863220db4ba..8bb25749a3da 100644
--- a/Documentation/devicetree/bindings/leds/leds-lp8860.txt
+++ b/Documentation/devicetree/bindings/leds/leds-lp8860.txt
@@ -47,4 +47,4 @@ led-controller@2d {
 }
 
 For more product information please see the link below:
-http://www.ti.com/product/lp8860-q1
+https://www.ti.com/product/lp8860-q1
diff --git a/Documentation/devicetree/bindings/leds/leds-pca955x.txt b/Documentation/devicetree/bindings/leds/leds-pca955x.txt
index 7984efb767b4..7a5830f8d5ab 100644
--- a/Documentation/devicetree/bindings/leds/leds-pca955x.txt
+++ b/Documentation/devicetree/bindings/leds/leds-pca955x.txt
@@ -26,9 +26,9 @@ LED sub-node properties:
 		from 0 to 15 for the pca9552
 		from 0 to  3 for the pca9553
 - type: (optional) either
-	PCA9532_TYPE_NONE
-	PCA9532_TYPE_LED
-	PCA9532_TYPE_GPIO
+	PCA955X_TYPE_NONE
+	PCA955X_TYPE_LED
+	PCA955X_TYPE_GPIO
 	see dt-bindings/leds/leds-pca955x.h (default to LED)
 - label : (optional)
 	see Documentation/devicetree/bindings/leds/common.txt