1* Common leds properties. 2 3LED and flash LED devices provide the same basic functionality as current 4regulators, but extended with LED and flash LED specific features like 5blinking patterns, flash timeout, flash faults and external flash strobe mode. 6 7Many LED devices expose more than one current output that can be connected 8to one or more discrete LED component. Since the arrangement of connections 9can influence the way of the LED device initialization, the LED components 10have to be tightly coupled with the LED device binding. They are represented 11by child nodes of the parent LED device binding. 12 13Optional properties for child nodes: 14- led-sources : List of device current outputs the LED is connected to. The 15 outputs are identified by the numbers that must be defined 16 in the LED device binding documentation. 17- label : The label for this LED. If omitted, the label is taken from the node 18 name (excluding the unit address). It has to uniquely identify 19 a device, i.e. no other LED class device can be assigned the same 20 label. 21 22- default-state : The initial state of the LED. Valid values are "on", "off", 23 and "keep". If the LED is already on or off and the default-state property is 24 set the to same value, then no glitch should be produced where the LED 25 momentarily turns off (or on). The "keep" setting will keep the LED at 26 whatever its current state is, without producing a glitch. The default is 27 off if this property is not present. 28 29- linux,default-trigger : This parameter, if present, is a 30 string defining the trigger assigned to the LED. Current triggers are: 31 "backlight" - LED will act as a back-light, controlled by the framebuffer 32 system 33 "default-on" - LED will turn on (but for leds-gpio see "default-state" 34 property in Documentation/devicetree/bindings/leds/leds-gpio.txt) 35 "heartbeat" - LED "double" flashes at a load average based rate 36 "disk-activity" - LED indicates disk activity 37 "ide-disk" - LED indicates IDE disk activity (deprecated), 38 in new implementations use "disk-activity" 39 "timer" - LED flashes at a fixed, configurable rate 40 "pattern" - LED alters the brightness for the specified duration with one 41 software timer (requires "led-pattern" property) 42 43- led-pattern : Array of integers with default pattern for certain triggers. 44 Each trigger may parse this property differently: 45 - one-shot : two numbers specifying delay on and delay off (in ms), 46 - timer : two numbers specifying delay on and delay off (in ms), 47 - pattern : the pattern is given by a series of tuples, of 48 brightness and duration (in ms). The exact format is 49 described in: 50 Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt 51 52 53- led-max-microamp : Maximum LED supply current in microamperes. This property 54 can be made mandatory for the board configurations 55 introducing a risk of hardware damage in case an excessive 56 current is set. 57 For flash LED controllers with configurable current this 58 property is mandatory for the LEDs in the non-flash modes 59 (e.g. torch or indicator). 60 61- panic-indicator : This property specifies that the LED should be used, 62 if at all possible, as a panic indicator. 63 64- trigger-sources : List of devices which should be used as a source triggering 65 this LED activity. Some LEDs can be related to a specific 66 device and should somehow indicate its state. E.g. USB 2.0 67 LED may react to device(s) in a USB 2.0 port(s). 68 Another common example is switch or router with multiple 69 Ethernet ports each of them having its own LED assigned 70 (assuming they are not hardwired). In such cases this 71 property should contain phandle(s) of related source 72 device(s). 73 In many cases LED can be related to more than one device 74 (e.g. one USB LED vs. multiple USB ports). Each source 75 should be represented by a node in the device tree and be 76 referenced by a phandle and a set of phandle arguments. A 77 length of arguments should be specified by the 78 #trigger-source-cells property in the source node. 79 80Required properties for flash LED child nodes: 81- flash-max-microamp : Maximum flash LED supply current in microamperes. 82- flash-max-timeout-us : Maximum timeout in microseconds after which the flash 83 LED is turned off. 84 85For controllers that have no configurable current the flash-max-microamp 86property can be omitted. 87For controllers that have no configurable timeout the flash-max-timeout-us 88property can be omitted. 89 90* Trigger source providers 91 92Each trigger source should be represented by a device tree node. It may be e.g. 93a USB port or an Ethernet device. 94 95Required properties for trigger source: 96- #trigger-source-cells : Number of cells in a source trigger. Typically 0 for 97 nodes of simple trigger sources (e.g. a specific USB 98 port). 99 100* Examples 101 102gpio-leds { 103 compatible = "gpio-leds"; 104 105 system-status { 106 label = "Status"; 107 linux,default-trigger = "heartbeat"; 108 gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>; 109 }; 110 111 usb { 112 gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>; 113 trigger-sources = <&ohci_port1>, <&ehci_port1>; 114 }; 115}; 116 117max77693-led { 118 compatible = "maxim,max77693-led"; 119 120 camera-flash { 121 label = "Flash"; 122 led-sources = <0>, <1>; 123 led-max-microamp = <50000>; 124 flash-max-microamp = <320000>; 125 flash-max-timeout-us = <500000>; 126 }; 127}; 128