1 * Common leds properties.
3 LED and flash LED devices provide the same basic functionality as current
4 regulators, but extended with LED and flash LED specific features like
5 blinking patterns, flash timeout, flash faults and external flash strobe mode.
7 Many LED devices expose more than one current output that can be connected
8 to one or more discrete LED component. Since the arrangement of connections
9 can influence the way of the LED device initialization, the LED components
10 have to be tightly coupled with the LED device binding. They are represented
11 by child nodes of the parent LED device binding.
13 Optional 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
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.
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
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)
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
50 Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt
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
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).
61 - panic-indicator : This property specifies that the LED should be used,
62 if at all possible, as a panic indicator.
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
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.
80 Required 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
85 For controllers that have no configurable current the flash-max-microamp
86 property can be omitted.
87 For controllers that have no configurable timeout the flash-max-timeout-us
88 property can be omitted.
90 * Trigger source providers
92 Each trigger source should be represented by a device tree node. It may be e.g.
93 a USB port or an Ethernet device.
95 Required 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
103 compatible = "gpio-leds";
107 linux,default-trigger = "heartbeat";
108 gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>;
112 gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
113 trigger-sources = <&ohci_port1>, <&ehci_port1>;
118 compatible = "maxim,max77693-led";
122 led-sources = <0>, <1>;
123 led-max-microamp = <50000>;
124 flash-max-microamp = <320000>;
125 flash-max-timeout-us = <500000>;