87 lines
3.2 KiB
YAML
87 lines
3.2 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/power/reset/gpio-restart.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: GPIO controlled reset
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maintainers:
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- Sebastian Reichel <sre@kernel.org>
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description: >
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Drive a GPIO line that can be used to restart the system from a restart handler.
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This binding supports level and edge triggered reset. At driver load time, the driver will
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request the given gpio line and install a restart handler. If the optional properties
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'open-source' is not found, the GPIO line will be driven in the inactive state. Otherwise its
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not driven until the restart is initiated.
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When the system is restarted, the restart handler will be invoked in priority order. The GPIO
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is configured as an output, and driven active, triggering a level triggered reset condition.
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This will also cause an inactive->active edge condition, triggering positive edge triggered
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reset. After a delay specified by active-delay, the GPIO is set to inactive, thus causing an
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active->inactive edge, triggering negative edge triggered reset. After a delay specified by
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inactive-delay, the GPIO is driven active again. After a delay specified by wait-delay, the
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restart handler completes allowing other restart handlers to be attempted.
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properties:
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compatible:
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const: gpio-restart
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gpios:
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description: The GPIO to set high/low, see "gpios property" in
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Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be low to reset the board
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set it to "Active Low", otherwise set GPIO to "Active High".
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open-source:
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$ref: /schemas/types.yaml#/definitions/flag
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description: Treat the GPIO as being open source and defer driving it to when the restart is
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initiated. If this optional property is not specified, the GPIO is initialized as an output
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in its inactive state.
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priority:
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$ref: /schemas/types.yaml#/definitions/uint32
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description: |
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A priority ranging from 0 to 255 (default 129) according to the following guidelines:
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0: Restart handler of last resort, with limited restart capabilities.
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128: Default restart handler; use if no other restart handler is expected to be available,
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and/or if restart functionality is sufficient to restart the entire system.
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255: Highest priority restart handler, will preempt all other restart handlers.
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minimum: 0
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maximum: 255
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default: 129
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active-delay:
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$ref: /schemas/types.yaml#/definitions/uint32
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description: Delay (default 100) to wait after driving gpio active [ms]
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default: 100
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inactive-delay:
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$ref: /schemas/types.yaml#/definitions/uint32
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description: Delay (default 100) to wait after driving gpio inactive [ms]
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default: 100
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wait-delay:
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$ref: /schemas/types.yaml#/definitions/uint32
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description: Delay (default 3000) to wait after completing restart sequence [ms]
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default: 100
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additionalProperties: false
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required:
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- compatible
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- gpios
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examples:
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- |
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gpio-restart {
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compatible = "gpio-restart";
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gpios = <&gpio 4 0>;
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priority = <128>;
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active-delay = <100>;
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inactive-delay = <100>;
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wait-delay = <3000>;
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};
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