Platform init design
Add a repository for initting platforms.
Change-Id: I9debc814ac17d4cf8c5f6fc78223560434eb9bc8
Signed-off-by: Ed Tanous <etanous@nvidia.com>
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+# Platform init
+
+Author: Ed Tanous (edtanous)
+
+Created: 7-21-25
+
+## Problem Description
+
+There are a number of platforms that require handling of state that requires
+interacting with hardware in a consolidated way. Some examples of this are:
+
+1. Resetting an i2c driver that initially is without power.
+2. Bringing up a power rail under the control of the BMC.
+3. Initing a power rail dependent on the state of a plug detect pin.
+
+## Background and References
+
+And any number of other cases. Some concrete examples of this kind of init of
+these things exists here. [1]
+
+Very routinely, significant bash scripts are used to do some of this init. Those
+bash scripts suffer some minor performance penalty on startup, and are generally
+checked into meta layers, reducing the reuse between platforms.
+
+## Requirements
+
+1. OpenBMC must be able to init a system with devices on power rails that it
+ controls.
+2. During the control of aformentioned power rails, the OpenBMC must be able to
+ monitor GPIO signals.
+3. OpenBMC must be able to reset i2c lines that might not be available.
+4. (secondary) Must be able to init multiple platforms from a single binary
+ (dc-scm)
+
+## Proposed Design
+
+Initially, a new repository would be created to house the platform-init for
+gb200nvl platform, and get static analysis autobumps, and recipes reused between
+platforms.
+
+Platforms will be separated by folder to ensure that platform owners can review
+and create their platform configurations as required, and identical to the
+meta-layer process that exists today.
+
+Top level structure will be
+
+platform_init.cpp platform1/init.cpp platform2/init.cpp
+
+Initially a cli argument will be used to compile the appropriate paths for a
+given platform. At some point in the future, some level of detection _may_ be
+added that allows detecting platforms at runtime. Design for that is to be
+determined based on future requirements.
+
+Guard rails will need to evolve over time, but initially this repository will
+not interact with DBus or the OpenBMC model. As defined (at this time) it is
+purely for initial bringup of hardware.
+
+## Alternatives Considered
+
+Status quo, continue building init scripts in bash. This leads to a lack of code
+reuse, and while some layers have done an excellent job keeping the code clean,
+it's still very difficult to refactor/consolidate.
+
+## Impacts
+
+1. Will require a new repository, recipe, and CI build.
+2. A new service will be launched for platforms opting into platform-init.
+
+### Organizational
+
+- Does this proposal require a new repository? Yes Request for the repository is
+ available[2]
+- Who will be the initial maintainer(s) of this repository? Ed Tanous and
+ Patrick Williams
+- Which repositories are expected to be modified to execute this design?
+ openbmc/openbmc New repository
+
+## Testing
+
+Testing section omitted. Platform boot will be tested using individual
+platforms, with no change.
+
+[1]:
+ https://github.com/openbmc/openbmc/blob/master/meta-nvidia/meta-gb200nvl-obmc/recipes-nvidia/platform-init/files/platform_init.cpp
+[2]: https://github.com/openbmc/technical-oversight-forum/issues/51