tree 28fc77b13100215f2983b170ec8bb24408743c07
parent de0813bee2778fe28f61a0ec3ff22ae2e44599dc
author Christoph Klee <chklee@google.com> 1716245715 +0000
committer CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com> 1716245715 +0000

pw_clock_tree: Generic clock tree management

This change introduces a module to implement clock
management of individual clock tree elements, such as clocks,
clock selectors or clock dividers.

The `ClockManager` controls the state of individual clock
tree elements and ensures that access to them is serialized.

Four main abstract class templates implement the different clock
tree elements to represent the clock tree of an embedded system.

The `Element` abstract class implements the reference counting
to ensure that a clock tree element can only get
enabled when all its dependent clock tree elements have been enabled.
Similarly, the different clock tree elements ensure that a clock
tree element gets disabled before the clock tree element it
was depending on can get disabled.

If enabling or disabling a clock tree element might require the
operation to block, the `ElementBlocking` class needs to be
used. Otherwise, the `ElementNonBlockingCannotFail` or
`ElementNonBlockingMightFail` class should be used depening on
whether enabling and disabling will always succeed, or whether it might
fail.

Change-Id: Ic4205ba8eb552b2558983c2b19b1b9e47a5d9687
Bug: 331672574
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/204310
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Christoph Klee <chklee@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
Reviewed-by: Austin Foxley <afoxley@google.com>