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 7title: GPIO controlled reset 8 9maintainers: 10 - Sebastian Reichel <sre@kernel.org> 11 12description: > 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 28allOf: 29 - $ref: restart-handler.yaml# 30 31properties: 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 64additionalProperties: false 65 66required: 67 - compatible 68 - gpios 69 70examples: 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 }; 80