Add CpoCmisApi

[bgallagher-nexthop]

Description

CmisApi has aggregate functions that read multiple registers and return a dict containing logically grouped information back to xcvrd. For instance, get_transceiver_info is a good example of one of these functions.

This PR implements CPO-specific subclass of CmisApi that splits those aggregate functions into smaller functions that return banked or non-banked information. Taking get_transceiver_info for example, there will now be 3 functions:

• get_banked_transceiver_info, which will return only bank-dependent information
• get_non_banked_transceiver_info, which will return only bank-independent information
• get_transceiver_info will continue to exist, but internally it will just call the two above functions and return the union of their output.

This functionality is limited to a CPO subclass since the ability to read banked and non-banked information independently is only required by CPO at this time.

Motivation and Context

For CPO, there is a desire to limit reading non-banked information from the hardware for each port because many ports may share the same device. Reading non-banked information multiple times from the same device for each port would waste i2c read bandwidth, so the functions have been split to allow xcvrd to selectively read non-banked information only as much as necessary and avoid duplicate reads.

How Has This Been Tested?

A new test class for CpoCmisApi has been introduced that will run all existing test-cases defined for CmisApi against the subclass. The subclass adds no new functionality, just exposes new functions.

[mssonicbld]

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[Copilot]

Pull request overview

This PR refactors CmisApi (CMIS transceiver API) aggregate “read-many-registers then return a dict” methods to expose separate banked vs non-banked entry points, enabling xcvrd (especially for CPO/shared-device scenarios) to avoid redundant non-banked EEPROM reads while preserving the existing aggregate APIs.

Changes:

• Split get_transceiver_info() into get_non_banked_transceiver_info() + get_banked_transceiver_info() and recompose in the original method.
• Split DOM reads/flags and status/status-flags similarly into banked and non-banked helpers, with the original aggregate methods now merging the two parts.
• Split the transceiver-info default dictionary into banked/non-banked subsets and keep an aggregate default dict.

Suppressed comments (1)

sonic_platform_base/sonic_xcvr/api/public/cmis.py:419

• Avoid the explicit line continuation ("\") here; it makes the indentation misleading and is prone to style/lint issues. This assignment fits on one line cleanly.

            xcvr_info["%s%d" % ("active_apsel_hostlane", lane)] = \
            apsel_dict["%s%d" % (consts.ACTIVE_APSEL_HOSTLANE, lane)]

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[prgeor]

@bgallagher-nexthop I was wondering if we should deal with this nuance in cpo specific CMIS api override?

[bgallagher-nexthop]

@bgallagher-nexthop I was wondering if we should deal with this nuance in cpo specific CMIS api override?

I think that approach would work too:

1. We could create a CpoCmisApi subclass of CmisApi
2. We could re-implement the aggregate methods like get_transceiver_info in that subclass, with the banked and non-banked variants also implemented.

I think the downside is that we will have a maintenance cost of keeping CpoCmisApi up-to-date. Any update to the overriden aggregate methods in CmisApi will also require making those same changes to CpoCmisApi. Or we accept that the CpoCmisApi can become stale as time goes on.

What do you think?

[mssonicbld]

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[bgallagher-nexthop]

Changed the approach to use a CPO specific subclass that splits some aggregate methods into banked / non-banked constituent methods instead of modifying CmisApi directly, as suggested by reviewers. Also got rid of get_transceiver_info from this class -- it does not require the banked / non-banked methods since it is only called once upon transceiver insertion.

[mssonicbld]

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