summaryrefslogtreecommitdiffstats
path: root/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/devicetree/bindings/power/reset/gpio-restart.yaml')
-rw-r--r--Documentation/devicetree/bindings/power/reset/gpio-restart.yaml86
1 files changed, 86 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml b/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml
new file mode 100644
index 000000000..a72d5c721
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/reset/gpio-restart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: GPIO controlled reset
+
+maintainers:
+ - Sebastian Reichel <sre@kernel.org>
+
+description: >
+ Drive a GPIO line that can be used to restart the system from a restart handler.
+
+ This binding supports level and edge triggered reset. At driver load time, the driver will
+ request the given gpio line and install a restart handler. If the optional properties
+ 'open-source' is not found, the GPIO line will be driven in the inactive state. Otherwise its
+ not driven until the restart is initiated.
+
+ When the system is restarted, the restart handler will be invoked in priority order. The GPIO
+ is configured as an output, and driven active, triggering a level triggered reset condition.
+ This will also cause an inactive->active edge condition, triggering positive edge triggered
+ reset. After a delay specified by active-delay, the GPIO is set to inactive, thus causing an
+ active->inactive edge, triggering negative edge triggered reset. After a delay specified by
+ inactive-delay, the GPIO is driven active again. After a delay specified by wait-delay, the
+ restart handler completes allowing other restart handlers to be attempted.
+
+properties:
+ compatible:
+ const: gpio-restart
+
+ gpios:
+ description: The GPIO to set high/low, see "gpios property" in
+ Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be low to reset the board
+ set it to "Active Low", otherwise set GPIO to "Active High".
+
+ open-source:
+ $ref: /schemas/types.yaml#/definitions/flag
+ description: Treat the GPIO as being open source and defer driving it to when the restart is
+ initiated. If this optional property is not specified, the GPIO is initialized as an output
+ in its inactive state.
+
+ priority:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description: |
+ A priority ranging from 0 to 255 (default 129) according to the following guidelines:
+
+ 0: Restart handler of last resort, with limited restart capabilities.
+ 128: Default restart handler; use if no other restart handler is expected to be available,
+ and/or if restart functionality is sufficient to restart the entire system.
+ 255: Highest priority restart handler, will preempt all other restart handlers.
+ minimum: 0
+ maximum: 255
+ default: 129
+
+ active-delay:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description: Delay (default 100) to wait after driving gpio active [ms]
+ default: 100
+
+ inactive-delay:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description: Delay (default 100) to wait after driving gpio inactive [ms]
+ default: 100
+
+ wait-delay:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description: Delay (default 3000) to wait after completing restart sequence [ms]
+ default: 100
+
+additionalProperties: false
+
+required:
+ - compatible
+ - gpios
+
+examples:
+ - |
+ gpio-restart {
+ compatible = "gpio-restart";
+ gpios = <&gpio 4 0>;
+ priority = <128>;
+ active-delay = <100>;
+ inactive-delay = <100>;
+ wait-delay = <3000>;
+ };