power/regulator/overview.rst

2 Linux voltage and current regulator framework
9 voltage and current regulators.
11 The intention is to allow systems to dynamically control regulator power output
13 regulators (where voltage output is controllable) and current sinks (where
14 current limit is controllable).
26   - Regulator
27                  - Electronic device that supplies power to other devices.
29                    some can control their output voltage and or current.
31                    Input Voltage -> Regulator -> Output Voltage
34   - PMIC
35                  - Power Management IC. An IC that contains numerous
39   - Consumer
40                  - Electronic device that is supplied power by a regulator.
41                    Consumers can be classified into two types:-
44                    current limit. It only needs to enable or disable its
49                    current limit to meet operation demands.
52   - Power Domain
53                  - Electronic circuit that is supplied its input power by the
54                    output power of a regulator, switch or by another power
57                    The supply regulator may be behind a switch(s). i.e.::
59                      Regulator -+-> Switch-1 -+-> Switch-2 --> [Consumer A]
61                                 |             +-> [Consumer B], [Consumer C]
63                                 +-> [Consumer D], [Consumer E]
65                    That is one regulator and three power domains:
67                    - Domain 1: Switch-1, Consumers D & E.
68                    - Domain 2: Switch-2, Consumers B & C.
69                    - Domain 3: Consumer A.
73                    Domain-1 --> Domain-2 --> Domain-3.
78                      Regulator-1 -+-> Regulator-2 -+-> [Consumer A]
80                                   +-> [Consumer B]
84                    - Domain 1: Regulator-2, Consumer B.
85                    - Domain 2: Consumer A.
89                    Domain-1 --> Domain-2
92   - Constraints
93                  - Constraints are used to define power levels for performance
94                    and hardware protection. Constraints exist at three levels:
96                    Regulator Level: This is defined by the regulator hardware
97                    operating parameters and is specified in the regulator
100                      - voltage output is in the range 800mV -> 3500mV.
101                      - regulator current output limit is 20mA @ 5V but is
108                      - Domain-1 voltage is 3300mV
109                      - Domain-2 voltage is 1400mV -> 1600mV
110                      - Domain-3 current limit is 0mA -> 20mA.
113                    dynamically setting voltage or current limit levels.
115                    e.g. a consumer backlight driver asks for a current increase
117                    to through the levels as follows :-
120                    request next current mA value in brightness table (the
124                    Power Domain: is the new current limit within the domain
128                    Regulator Domains: is the new current limit within the
129                    regulator operating parameters for input/output voltage.
131                    If the regulator request passes all the constraint tests
132                    then the new regulator value is applied.
139 relevant to non SoC devices and is split into the following four interfaces:-
145       drivers can get and put a regulator (like they can with clocks atm) and
146       get/set voltage, current limit, mode, enable and disable. This should
147       allow consumers complete control over their supply voltage and current
149       systems with no regulator based power control.
151         See Documentation/power/regulator/consumer.rst
153    2. Regulator driver interface.
155       This allows regulator drivers to register their regulators and provide
157       regulator events to clients.
159         See Documentation/power/regulator/regulator.rst
164       voltage/current domains (with constraints) for each regulator. It can
165       provide regulator constraints that will prevent device damage through
167       allows the creation of a regulator tree whereby some regulators are
170         See Documentation/power/regulator/machine.rst
174       The framework also exports a lot of useful voltage/current/opmode data to
178         See Documentation/ABI/testing/sysfs-class-regulator