ACPI: PNP: Drop PNP0C01 and PNP0C02 from acpi_pnp_device_ids[]

ACPI: PNP: Drop PNP0C01 and PNP0C02 from acpi_pnp_device_ids[]

There is a long-standing problem with ACPI device enumeration that
if the given device has a compatible ID which is one of the generic
system resource device IDs (PNP0C01 and PNP0C02), it will be claimed
by the PNP scan handler and it will not be represented as a platform
device, so it cannot be handled by a platform driver.

Drivers have been working around this issue by "manually" creating
platform devices that they can bind to (see the Intel HID driver for
one example) or adding their device IDs to acpi_nonpnp_device_ids[].
None of the above is particularly clean though and the only reason why
the PNP0C01 and PNP0C02 device IDs are present in acpi_pnp_device_ids[]
is to allow the legacy PNP system driver to bind to those devices and
reserve their resources so they are not used going forward.

Obviously, to address this problem PNP0C01 and PNP0C02 need to be
dropped from acpi_pnp_device_ids[], but doing so without making any
other changes would be problematic because the ACPI core would then
create platform devices for the generic system resource device objects
and that would not work on all systems for two reasons.  First, the
PNP system driver explicitly avoids reserving I/O resources below the
"standard PC hardware" boundary, 0x100, to avoid conflicts in that range
(one possible case when this may happen is when the CMOS RTC driver is
involved), but the platform device creation code does not do that.
Second, there may be resource conflicts between the "system" devices and
the other devices in the system, possibly including conflicts with PCI
BARs.  Registering the PNP system driver via fs_initcall() helps to
manage those conflicts, even though it does not make them go away.
Resource conflicts during the registration of "motherboard resources"
that occur after PCI has claimed BARs are harmless as a rule and do
not need to be addressed in any specific way.

To overcome the issues mentioned above, use the observation that it
is not actually necessary to create any device objects in addition
to struct acpi_device ones in order to reserve the "system" device
resources because that can be done directly in the ACPI device
enumeration code.

Namely, modify acpi_default_enumeration() to add the given ACPI device
object to a special "system devices" list if its _HID is either PNP0C01
or PNP0C02 without creating a platform device for it.  Next, add a new
special acpi_scan_claim_resources() function that will be run via
fs_initcall() and will walk that list and reserve resources for each
device in it along the lines of what the PNP system driver does.

Having made the above changes, drop PNP0C01 and PNP0C02 from
acpi_pnp_device_ids[] which will allow platform devices to be created
for ACPI device objects whose _CID lists contain PNP0C01 or PNP0C02,
but the _HID is not in acpi_pnp_device_ids[].

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
[ rjw: Drop a leftover comment and add a new one elsewhere ]
Link: https://patch.msgid.link/9550709.CDJkKcVGEf@rafael.j.wysocki
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>