Add ACPI support for _CLS
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Authored by andrew on Dec 6 2016, 5:16 PM.

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jkim
jhb

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rS310154: Add support to read the _CLS entry if it's present. It is used by

Summary

Add support to read the _CLS entry if it's present. It is used by
memory-mapped devices that are normally PCIe drives. Devices can then
use the existing pci_get_class, etc. accessors to query this data.

The ivar values are different enough from the existing ACPI and ISA
values to not conflict.

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andrew updated this revision to Diff 22732.Dec 6 2016, 5:16 PM

andrew retitled this revision from to Add ACPI support for _CLS.

andrew updated this object.

andrew edited the test plan for this revision. (Show Details)

andrew added reviewers: jhb, jkim.

andrew added a subscriber: emaste.

My only thought is if you want to read _CLS once during device enumeration and cache it's value in 'struct acpi_device' rather than invoking it for each ivar access. Aside from that this looks fine.

Read _CLS once

jhb added inline comments.Dec 14 2016, 12:09 AM

sys/dev/acpica/acpi.c
930	While this would seem useful, it's probably not in practice. Accessors like 'pci_get_class()' have no way to return an error. They always return whatever is in '*result' so the caller will just get garbage. I think it would be better to always return a value, but use specific invalid values for devices without _CLS (namely 0xff). You can do this by just setting acpi_cls_class to '0xffffff' when enumerating a device if _CLS isn't present or has an error and then having these bits of code return the acpi_cls_class value unconditionally.
sys/dev/acpica/acpivar.h
89	If you do the above suggestion you won't need this variable.

Return 0xff if _CLS is missing

I should have noticed earlier, but it would be nice to use the same 'ad_' prefix as the rest of the structure members, and you probably don't need a blank line between ad_flags and the new field.

This revision is now accepted and ready to land.Dec 15 2016, 8:43 PM

Closed by commit rS310154: Add support to read the _CLS entry if it's present. It is used by (authored by andrew). · Explain WhyDec 16 2016, 10:40 AM

This revision was automatically updated to reflect the committed changes.