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/gpio/led.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
41- led-max-microamp : Maximum LED supply current in microamperes. This property
42                     can be made mandatory for the board configurations
43                     introducing a risk of hardware damage in case an excessive
44                     current is set.
45                     For flash LED controllers with configurable current this
46                     property is mandatory for the LEDs in the non-flash modes
47                     (e.g. torch or indicator).
48
49- panic-indicator : This property specifies that the LED should be used,
50		    if at all possible, as a panic indicator.
51
52- trigger-sources : List of devices which should be used as a source triggering
53		    this LED activity. Some LEDs can be related to a specific
54		    device and should somehow indicate its state. E.g. USB 2.0
55		    LED may react to device(s) in a USB 2.0 port(s).
56		    Another common example is switch or router with multiple
57		    Ethernet ports each of them having its own LED assigned
58		    (assuming they are not hardwired). In such cases this
59		    property should contain phandle(s) of related source
60		    device(s).
61		    In many cases LED can be related to more than one device
62		    (e.g. one USB LED vs. multiple USB ports). Each source
63		    should be represented by a node in the device tree and be
64		    referenced by a phandle and a set of phandle arguments. A
65		    length of arguments should be specified by the
66		    #trigger-source-cells property in the source node.
67
68Required properties for flash LED child nodes:
69- flash-max-microamp : Maximum flash LED supply current in microamperes.
70- flash-max-timeout-us : Maximum timeout in microseconds after which the flash
71                         LED is turned off.
72
73For controllers that have no configurable current the flash-max-microamp
74property can be omitted.
75For controllers that have no configurable timeout the flash-max-timeout-us
76property can be omitted.
77
78* Trigger source providers
79
80Each trigger source should be represented by a device tree node. It may be e.g.
81a USB port or an Ethernet device.
82
83Required properties for trigger source:
84- #trigger-source-cells : Number of cells in a source trigger. Typically 0 for
85			  nodes of simple trigger sources (e.g. a specific USB
86			  port).
87
88* Examples
89
90gpio-leds {
91	compatible = "gpio-leds";
92
93	system-status {
94		label = "Status";
95		linux,default-trigger = "heartbeat";
96		gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>;
97	};
98
99	usb {
100		gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
101		trigger-sources = <&ohci_port1>, <&ehci_port1>;
102	};
103};
104
105max77693-led {
106	compatible = "maxim,max77693-led";
107
108	camera-flash {
109		label = "Flash";
110		led-sources = <0>, <1>;
111		led-max-microamp = <50000>;
112		flash-max-microamp = <320000>;
113		flash-max-timeout-us = <500000>;
114	};
115};
116