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Diffstat (limited to 'Documentation/devicetree/bindings/leds/common.txt')
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diff --git a/Documentation/devicetree/bindings/leds/common.txt b/Documentation/devicetree/bindings/leds/common.txt new file mode 100644 index 000000000..aa1399814 --- /dev/null +++ b/Documentation/devicetree/bindings/leds/common.txt @@ -0,0 +1,115 @@ +* Common leds properties. + +LED and flash LED devices provide the same basic functionality as current +regulators, but extended with LED and flash LED specific features like +blinking patterns, flash timeout, flash faults and external flash strobe mode. + +Many LED devices expose more than one current output that can be connected +to one or more discrete LED component. Since the arrangement of connections +can influence the way of the LED device initialization, the LED components +have to be tightly coupled with the LED device binding. They are represented +by child nodes of the parent LED device binding. + +Optional properties for child nodes: +- led-sources : List of device current outputs the LED is connected to. The + outputs are identified by the numbers that must be defined + in the LED device binding documentation. +- label : The label for this LED. If omitted, the label is taken from the node + name (excluding the unit address). It has to uniquely identify + a device, i.e. no other LED class device can be assigned the same + label. + +- default-state : The initial state of the LED. Valid values are "on", "off", + and "keep". If the LED is already on or off and the default-state property is + set the to same value, then no glitch should be produced where the LED + momentarily turns off (or on). The "keep" setting will keep the LED at + whatever its current state is, without producing a glitch. The default is + off if this property is not present. + +- linux,default-trigger : This parameter, if present, is a + string defining the trigger assigned to the LED. Current triggers are: + "backlight" - LED will act as a back-light, controlled by the framebuffer + system + "default-on" - LED will turn on (but for leds-gpio see "default-state" + property in Documentation/devicetree/bindings/leds/leds-gpio.txt) + "heartbeat" - LED "double" flashes at a load average based rate + "disk-activity" - LED indicates disk activity + "ide-disk" - LED indicates IDE disk activity (deprecated), + in new implementations use "disk-activity" + "timer" - LED flashes at a fixed, configurable rate + +- led-max-microamp : Maximum LED supply current in microamperes. This property + can be made mandatory for the board configurations + introducing a risk of hardware damage in case an excessive + current is set. + For flash LED controllers with configurable current this + property is mandatory for the LEDs in the non-flash modes + (e.g. torch or indicator). + +- panic-indicator : This property specifies that the LED should be used, + if at all possible, as a panic indicator. + +- trigger-sources : List of devices which should be used as a source triggering + this LED activity. Some LEDs can be related to a specific + device and should somehow indicate its state. E.g. USB 2.0 + LED may react to device(s) in a USB 2.0 port(s). + Another common example is switch or router with multiple + Ethernet ports each of them having its own LED assigned + (assuming they are not hardwired). In such cases this + property should contain phandle(s) of related source + device(s). + In many cases LED can be related to more than one device + (e.g. one USB LED vs. multiple USB ports). Each source + should be represented by a node in the device tree and be + referenced by a phandle and a set of phandle arguments. A + length of arguments should be specified by the + #trigger-source-cells property in the source node. + +Required properties for flash LED child nodes: +- flash-max-microamp : Maximum flash LED supply current in microamperes. +- flash-max-timeout-us : Maximum timeout in microseconds after which the flash + LED is turned off. + +For controllers that have no configurable current the flash-max-microamp +property can be omitted. +For controllers that have no configurable timeout the flash-max-timeout-us +property can be omitted. + +* Trigger source providers + +Each trigger source should be represented by a device tree node. It may be e.g. +a USB port or an Ethernet device. + +Required properties for trigger source: +- #trigger-source-cells : Number of cells in a source trigger. Typically 0 for + nodes of simple trigger sources (e.g. a specific USB + port). + +* Examples + +gpio-leds { + compatible = "gpio-leds"; + + system-status { + label = "Status"; + linux,default-trigger = "heartbeat"; + gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>; + }; + + usb { + gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>; + trigger-sources = <&ohci_port1>, <&ehci_port1>; + }; +}; + +max77693-led { + compatible = "maxim,max77693-led"; + + camera-flash { + label = "Flash"; + led-sources = <0>, <1>; + led-max-microamp = <50000>; + flash-max-microamp = <320000>; + flash-max-timeout-us = <500000>; + }; +}; |