| Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 1 | # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) |
| 2 | %YAML 1.2 |
| 3 | --- |
| 4 | $id: http://devicetree.org/schemas/power/reset/gpio-restart.yaml# |
| 5 | $schema: http://devicetree.org/meta-schemas/core.yaml# |
| 6 | |
| 7 | title: GPIO controlled reset |
| 8 | |
| 9 | maintainers: |
| 10 | - Sebastian Reichel <sre@kernel.org> |
| 11 | |
| 12 | description: > |
| 13 | Drive a GPIO line that can be used to restart the system from a restart handler. |
| 14 | |
| 15 | This binding supports level and edge triggered reset. At driver load time, the driver will |
| 16 | request the given gpio line and install a restart handler. If the optional properties |
| 17 | 'open-source' is not found, the GPIO line will be driven in the inactive state. Otherwise its |
| 18 | not driven until the restart is initiated. |
| 19 | |
| 20 | When the system is restarted, the restart handler will be invoked in priority order. The GPIO |
| 21 | is configured as an output, and driven active, triggering a level triggered reset condition. |
| 22 | This will also cause an inactive->active edge condition, triggering positive edge triggered |
| 23 | reset. After a delay specified by active-delay, the GPIO is set to inactive, thus causing an |
| 24 | active->inactive edge, triggering negative edge triggered reset. After a delay specified by |
| 25 | inactive-delay, the GPIO is driven active again. After a delay specified by wait-delay, the |
| 26 | restart handler completes allowing other restart handlers to be attempted. |
| 27 | |
| 28 | allOf: |
| 29 | - $ref: restart-handler.yaml# |
| 30 | |
| 31 | properties: |
| 32 | compatible: |
| 33 | const: gpio-restart |
| 34 | |
| 35 | gpios: |
| 36 | description: The GPIO to set high/low, see "gpios property" in |
| 37 | Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be low to reset the board |
| 38 | set it to "Active Low", otherwise set GPIO to "Active High". |
| 39 | |
| 40 | open-source: |
| 41 | $ref: /schemas/types.yaml#/definitions/flag |
| 42 | description: Treat the GPIO as being open source and defer driving it to when the restart is |
| 43 | initiated. If this optional property is not specified, the GPIO is initialized as an output |
| 44 | in its inactive state. |
| 45 | |
| 46 | priority: |
| 47 | default: 129 |
| 48 | |
| 49 | active-delay: |
| 50 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 51 | description: Delay (default 100) to wait after driving gpio active [ms] |
| 52 | default: 100 |
| 53 | |
| 54 | inactive-delay: |
| 55 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 56 | description: Delay (default 100) to wait after driving gpio inactive [ms] |
| 57 | default: 100 |
| 58 | |
| 59 | wait-delay: |
| 60 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 61 | description: Delay (default 3000) to wait after completing restart sequence [ms] |
| 62 | default: 100 |
| 63 | |
| 64 | additionalProperties: false |
| 65 | |
| 66 | required: |
| 67 | - compatible |
| 68 | - gpios |
| 69 | |
| 70 | examples: |
| 71 | - | |
| 72 | gpio-restart { |
| 73 | compatible = "gpio-restart"; |
| 74 | gpios = <&gpio 4 0>; |
| 75 | priority = <128>; |
| 76 | active-delay = <100>; |
| 77 | inactive-delay = <100>; |
| 78 | wait-delay = <3000>; |
| 79 | }; |