Merge tag 'leds-for-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds

Pull LED updates from Jacek Anaszewski:
 "LED core fixes and improvements:

      - avoid races with workqueue
      - Kconfig: pedantic cleanup
      - small fixes for Flash class description

  leds-lt3593:

      - remove unneeded assignment in lt3593_led_probe
      - drop pdata handling code

  leds-blinkm:

      - clean up double assignment to data->i2c_addr

  leds-pca955x, leds-pca963x:

      - revert ACPI support, as it turned out that there is no evidence
          of officially registered ACPI IDs for these devices.
      - make use of device property API

  leds-as3645a:

      - switch to fwnode property API

  LED related addition to ACPI documentation:

      - document how to refer to LEDs from remote nodes

  LED related fix to ALSA line6/toneport driver:

      - avoid polluting led_* namespace

  And lm3532 driver relocation from MFD to LED subsystem, accompanied by
  various improvements and optimizations; it entails also a change in
  omap4-droid4-xt894.dts:

      - leds: lm3532: Introduce the lm3532 LED driver
      - mfd: ti-lmu: Remove LM3532 backlight driver references
      - ARM: dts: omap4-droid4: Update backlight dt properties
      - dt: lm3532: Add lm3532 dt doc and update ti_lmu doc"

* tag 'leds-for-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
  leds: avoid races with workqueue
  ALSA: line6: Avoid polluting led_* namespace
  leds: lm3532: Introduce the lm3532 LED driver
  mfd: ti-lmu: Remove LM3532 backlight driver references
  ARM: dts: omap4-droid4: Update backlight dt properties
  dt: lm3532: Add lm3532 dt doc and update ti_lmu doc
  leds: Small fixes for Flash class description
  leds: blinkm: clean up double assignment to data->i2c_addr
  leds: pca963x: Make use of device property API
  leds: pca955x: Make use of device property API
  leds: lt3593: Remove unneeded assignment in lt3593_led_probe
  leds: lt3593: drop pdata handling code
  leds: pca955x: Revert "Add ACPI support"
  leds: pca963x: Revert "Add ACPI support"
  drivers: leds: Kconfig: pedantic cleanups
  ACPI: Document how to refer to LEDs from remote nodes
  leds: as3645a: Switch to fwnode property API

1 files changed, 99 insertions, 0 deletions

diff --git a/Documentation/acpi/dsd/leds.txt b/Documentation/acpi/dsd/leds.txt
new file mode 100644
index 000000000000..81a63af42ed2
--- /dev/null
+++ b/Documentation/acpi/dsd/leds.txt
@@ -0,0 +1,99 @@
+Describing and referring to LEDs in ACPI
+
+Individual LEDs are described by hierarchical data extension [6] nodes under the
+device node, the LED driver chip. The "reg" property in the LED specific nodes
+tells the numerical ID of each individual LED output to which the LEDs are
+connected. [3] The hierarchical data nodes are named "led@X", where X is the
+number of the LED output.
+
+Referring to LEDs in Device tree is documented in [4], in "flash-leds" property
+documentation. In short, LEDs are directly referred to by using phandles.
+
+While Device tree allows referring to any node in the tree[1], in ACPI
+references are limited to device nodes only [2]. For this reason using the same
+mechanism on ACPI is not possible. A mechanism to refer to non-device ACPI nodes
+is documented in [7].
+
+ACPI allows (as does DT) using integer arguments after the reference. A
+combination of the LED driver device reference and an integer argument,
+referring to the "reg" property of the relevant LED, is used to identify
+individual LEDs. The value of the "reg" property is a contract between the
+firmware and software, it uniquely identifies the LED driver outputs.
+
+Under the LED driver device, The first hierarchical data extension package list
+entry shall contain the string "led@" followed by the number of the LED,
+followed by the referred object name. That object shall be named "LED" followed
+by the number of the LED.
+
+An ASL example of a camera sensor device and a LED driver device for two LEDs.
+Objects not relevant for LEDs or the references to them have been omitted.
+
+	Device (LED)
+	{
+		Name (_DSD, Package () {
+			ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
+			Package () {
+				Package () { "led@0", LED0 },
+				Package () { "led@1", LED1 },
+			}
+		})
+		Name (LED0, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () { "reg", 0 },
+				Package () { "flash-max-microamp", 1000000 },
+				Package () { "flash-timeout-us", 200000 },
+				Package () { "led-max-microamp", 100000 },
+				Package () { "label", "white:flash" },
+			}
+		})
+		Name (LED1, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () { "reg", 1 },
+				Package () { "led-max-microamp", 10000 },
+				Package () { "label", "red:indicator" },
+			}
+		})
+	}
+
+	Device (SEN)
+	{
+		Name (_DSD, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () {
+					"flash-leds",
+					Package () { ^LED, "led@0", ^LED, "led@1" },
+				}
+			}
+		})
+	}
+
+where
+
+	LED	LED driver device
+	LED0	First LED
+	LED1	Second LED
+	SEN	Camera sensor device (or another device the LED is
+		related to)
+
+[1] Device tree. <URL:http://www.devicetree.org>, referenced 2019-02-21.
+
+[2] Advanced Configuration and Power Interface Specification.
+    <URL:https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf>,
+    referenced 2019-02-21.
+
+[3] Documentation/devicetree/bindings/leds/common.txt
+
+[4] Documentation/devicetree/bindings/media/video-interfaces.txt
+
+[5] Device Properties UUID For _DSD.
+    <URL:http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf>,
+    referenced 2019-02-21.
+
+[6] Hierarchical Data Extension UUID For _DSD.
+    <URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.1.pdf>,
+    referenced 2019-02-21.
+
+[7] Documentation/acpi/dsd/data-node-reference.txt