The on-off manager infrastructure is designed to robust asynchronous
transition between binary states where multiple clients may be
initiating a transition from any context. The actual transition is
performed using a manager that tracks the current state and pending
operations. Requests are initiated by passing a reference to an
onoff_client object that holds client state including the notification
mechanism.
This API may be used in subsystems where the transitions for a
particular driver are always synchronous and isr-ok, e.g. setting a
SoC-controlled GPIO. In this situation the full on-off manager
infrastructure is wasteful. All we need is a record of the service
state: off, active count, or error.
Add a data structure and an API that can be used to replace the onoff
manager functionality in a situation where all transitions are isr-ok
and synchronous while retaining compatible behavior from the client
perspective.
Signed-off-by: Peter A. Bigot <pab@pabigot.com>
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