linux_dsm_epyc7002/Documentation/devicetree/bindings/leds/leds-gpio.txt
Andrew Jeffery 0f34f95876 dt-bindings: leds: gpio: Add optional retain-state-shutdown property
On Baseboard Management Controller (BMC) systems it's sometimes
necessary for a LED to retain its state across a BMC reset (which is
independent of the host system state). Add a devicetree property to
describe this behaviour. The property would typically be used in
conjunction with 'default-state = "keep"'.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Acked-by: Pavel Machek <pavel@ucw.cz>
Tested-by: Brandon Wyman <bjwyman@gmail.com>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
2017-08-29 21:10:40 +02:00

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LEDs connected to GPIO lines
Required properties:
- compatible : should be "gpio-leds".
Each LED is represented as a sub-node of the gpio-leds device. Each
node's name represents the name of the corresponding LED.
LED sub-node properties:
- gpios : Should specify the LED's GPIO, see "gpios property" in
Documentation/devicetree/bindings/gpio/gpio.txt. Active low LEDs should be
indicated using flags in the GPIO specifier.
- label : (optional)
see Documentation/devicetree/bindings/leds/common.txt
- linux,default-trigger : (optional)
see Documentation/devicetree/bindings/leds/common.txt
- default-state: (optional) The initial state of the LED.
see Documentation/devicetree/bindings/leds/common.txt
- retain-state-suspended: (optional) The suspend state can be retained.Such
as charge-led gpio.
- retain-state-shutdown: (optional) Retain the state of the LED on shutdown.
Useful in BMC systems, for example when the BMC is rebooted while the host
remains up.
- panic-indicator : (optional)
see Documentation/devicetree/bindings/leds/common.txt
Examples:
#include <dt-bindings/gpio/gpio.h>
leds {
compatible = "gpio-leds";
hdd {
label = "Disk Activity";
gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
linux,default-trigger = "disk-activity";
};
fault {
gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
/* Keep LED on if BIOS detected hardware fault */
default-state = "keep";
};
};
run-control {
compatible = "gpio-leds";
red {
gpios = <&mpc8572 6 GPIO_ACTIVE_HIGH>;
default-state = "off";
};
green {
gpios = <&mpc8572 7 GPIO_ACTIVE_HIGH>;
default-state = "on";
};
};
leds {
compatible = "gpio-leds";
charger-led {
gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>;
linux,default-trigger = "max8903-charger-charging";
retain-state-suspended;
};
};