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0f34f95876
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>
67 lines
1.7 KiB
Plaintext
67 lines
1.7 KiB
Plaintext
LEDs connected to GPIO lines
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Required properties:
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- compatible : should be "gpio-leds".
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Each LED is represented as a sub-node of the gpio-leds device. Each
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node's name represents the name of the corresponding LED.
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LED sub-node properties:
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- gpios : Should specify the LED's GPIO, see "gpios property" in
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Documentation/devicetree/bindings/gpio/gpio.txt. Active low LEDs should be
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indicated using flags in the GPIO specifier.
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- label : (optional)
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see Documentation/devicetree/bindings/leds/common.txt
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- linux,default-trigger : (optional)
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see Documentation/devicetree/bindings/leds/common.txt
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- default-state: (optional) The initial state of the LED.
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see Documentation/devicetree/bindings/leds/common.txt
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- retain-state-suspended: (optional) The suspend state can be retained.Such
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as charge-led gpio.
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- retain-state-shutdown: (optional) Retain the state of the LED on shutdown.
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Useful in BMC systems, for example when the BMC is rebooted while the host
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remains up.
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- panic-indicator : (optional)
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see Documentation/devicetree/bindings/leds/common.txt
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Examples:
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#include <dt-bindings/gpio/gpio.h>
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leds {
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compatible = "gpio-leds";
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hdd {
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label = "Disk Activity";
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gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
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linux,default-trigger = "disk-activity";
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};
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fault {
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gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
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/* Keep LED on if BIOS detected hardware fault */
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default-state = "keep";
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};
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};
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run-control {
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compatible = "gpio-leds";
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red {
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gpios = <&mpc8572 6 GPIO_ACTIVE_HIGH>;
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default-state = "off";
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};
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green {
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gpios = <&mpc8572 7 GPIO_ACTIVE_HIGH>;
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default-state = "on";
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};
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};
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leds {
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compatible = "gpio-leds";
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charger-led {
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gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>;
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linux,default-trigger = "max8903-charger-charging";
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retain-state-suspended;
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};
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};
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