1 # SPDX-License-Identifier: (GPL-2.0-only OR BS !! 1 # SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
2 %YAML 1.2 2 %YAML 1.2
3 --- 3 ---
4 $id: http://devicetree.org/schemas/power/reset 4 $id: http://devicetree.org/schemas/power/reset/gpio-restart.yaml#
5 $schema: http://devicetree.org/meta-schemas/co 5 $schema: http://devicetree.org/meta-schemas/core.yaml#
6 6
7 title: GPIO controlled reset 7 title: GPIO controlled reset
8 8
9 maintainers: 9 maintainers:
10 - Sebastian Reichel <sre@kernel.org> 10 - Sebastian Reichel <sre@kernel.org>
11 11
12 description: > 12 description: >
13 Drive a GPIO line that can be used to restar 13 Drive a GPIO line that can be used to restart the system from a restart handler.
14 14
15 This binding supports level and edge trigger 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 re 16 request the given gpio line and install a restart handler. If the optional properties
17 'open-source' is not found, the GPIO line wi 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. 18 not driven until the restart is initiated.
19 19
20 When the system is restarted, the restart ha 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 activ 21 is configured as an output, and driven active, triggering a level triggered reset condition.
22 This will also cause an inactive->active edg 22 This will also cause an inactive->active edge condition, triggering positive edge triggered
23 reset. After a delay specified by active-del 23 reset. After a delay specified by active-delay, the GPIO is set to inactive, thus causing an
24 active->inactive edge, triggering negative e 24 active->inactive edge, triggering negative edge triggered reset. After a delay specified by
25 inactive-delay, the GPIO is driven active ag 25 inactive-delay, the GPIO is driven active again. After a delay specified by wait-delay, the
26 restart handler completes allowing other res 26 restart handler completes allowing other restart handlers to be attempted.
27 27
28 allOf: <<
29 - $ref: restart-handler.yaml# <<
30 <<
31 properties: 28 properties:
32 compatible: 29 compatible:
33 const: gpio-restart 30 const: gpio-restart
34 31
35 gpios: 32 gpios:
36 description: The GPIO to set high/low, see 33 description: The GPIO to set high/low, see "gpios property" in
37 Documentation/devicetree/bindings/gpio/g 34 Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be low to reset the board
38 set it to "Active Low", otherwise set GP 35 set it to "Active Low", otherwise set GPIO to "Active High".
39 36
40 open-source: 37 open-source:
41 $ref: /schemas/types.yaml#/definitions/fla 38 $ref: /schemas/types.yaml#/definitions/flag
42 description: Treat the GPIO as being open 39 description: Treat the GPIO as being open source and defer driving it to when the restart is
43 initiated. If this optional property is 40 initiated. If this optional property is not specified, the GPIO is initialized as an output
44 in its inactive state. 41 in its inactive state.
45 42
46 priority: 43 priority:
>> 44 $ref: /schemas/types.yaml#/definitions/uint32
>> 45 description: |
>> 46 A priority ranging from 0 to 255 (default 129) according to the following guidelines:
>> 47
>> 48 0: Restart handler of last resort, with limited restart capabilities.
>> 49 128: Default restart handler; use if no other restart handler is expected to be available,
>> 50 and/or if restart functionality is sufficient to restart the entire system.
>> 51 255: Highest priority restart handler, will preempt all other restart handlers.
>> 52 minimum: 0
>> 53 maximum: 255
47 default: 129 54 default: 129
48 55
49 active-delay: 56 active-delay:
50 $ref: /schemas/types.yaml#/definitions/uin 57 $ref: /schemas/types.yaml#/definitions/uint32
51 description: Delay (default 100) to wait a 58 description: Delay (default 100) to wait after driving gpio active [ms]
52 default: 100 59 default: 100
53 60
54 inactive-delay: 61 inactive-delay:
55 $ref: /schemas/types.yaml#/definitions/uin 62 $ref: /schemas/types.yaml#/definitions/uint32
56 description: Delay (default 100) to wait a 63 description: Delay (default 100) to wait after driving gpio inactive [ms]
57 default: 100 64 default: 100
58 65
59 wait-delay: 66 wait-delay:
60 $ref: /schemas/types.yaml#/definitions/uin 67 $ref: /schemas/types.yaml#/definitions/uint32
61 description: Delay (default 3000) to wait 68 description: Delay (default 3000) to wait after completing restart sequence [ms]
62 default: 100 69 default: 100
63 70
64 additionalProperties: false 71 additionalProperties: false
65 72
66 required: 73 required:
67 - compatible 74 - compatible
68 - gpios 75 - gpios
69 76
70 examples: 77 examples:
71 - | 78 - |
72 gpio-restart { 79 gpio-restart {
73 compatible = "gpio-restart"; 80 compatible = "gpio-restart";
74 gpios = <&gpio 4 0>; 81 gpios = <&gpio 4 0>;
75 priority = <128>; 82 priority = <128>;
76 active-delay = <100>; 83 active-delay = <100>;
77 inactive-delay = <100>; 84 inactive-delay = <100>;
78 wait-delay = <3000>; 85 wait-delay = <3000>;
79 }; 86 };
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