1 .. SPDX-License-Identifier: GPL-2.0-only
2 .. Copyright 2024 Linaro Ltd.
3
4 ====================
5 Power Sequencing API
6 ====================
7
8 :Author: Bartosz Golaszewski
9
10 Introduction
11 ============
12
13 This framework is designed to abstract complex
14 shared between multiple logical devices in the
15
16 The intention is to allow consumers to obtain
17 exposed by the power sequence provider and del
18 control of the underlying resources as well as
19 mitigate any potential conflicts between multi
20
21 Glossary
22 --------
23
24 The power sequencing API uses a number of term
25
26 Unit
27
28 A unit is a discreet chunk of a power sequ
29 enable a set of regulators, another may en
30 define dependencies in the form of other u
31 it itself can be.
32
33 Target
34
35 A target is a set of units (composed of th
36 dependencies) that a consumer selects by i
37 to the power sequencer. Via the dependency
38 share the same parts of a power sequence b
39 irrelevant.
40
41 Descriptor
42
43 A handle passed by the pwrseq core to ever
44 entry point to the provider layer. It ensu
45 users and keeps reference counting consist
46
47 Consumer interface
48 ==================
49
50 The consumer API is aimed to be as simple as p
51 getting a descriptor from the power sequencer
52 specify the name of the target it wants to rea
53 pwrseq_power_up(). The descriptor can be relea
54 the consumer can request the powering down of
55 pwrseq_power_off(). Note that there is no guar
56 will have any effect as there may be multiple
57 who may keep them active.
58
59 Provider interface
60 ==================
61
62 The provider API is admittedly not nearly as s
63 consumers but it makes up for it in flexibilit
64
65 Each provider can logically split the power-up
66 (units) and define their dependencies. They ca
67 consumers may use as the final point in the se
68
69 To that end the providers fill out a set of co
70 register with the pwrseq subsystem by calling
71
72 Dynamic consumer matching
73 -------------------------
74
75 The main difference between pwrseq and other l
76 mechanism for dynamic matching of consumers an
77 provider driver must implement the `match()` c
78 core when registering with the subsystems.
79
80 When a client requests a sequencer handle, the
81 every registered provider and let it flexibly
82 client device is indeed its consumer. For exam
83 device-tree node representing a power manageme
84 consumer driver controls one of its modules, t
85 relevant regulator supply properties in device
86 the PMU to the consumer.
87
88 API reference
89 =============
90
91 .. kernel-doc:: include/linux/pwrseq/provider.
92 :internal:
93
94 .. kernel-doc:: drivers/power/sequencing/core.
95 :export:
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