On x86, as a rule the CMOS RTC address space handler is set up by the
CMOS RTC ACPI scan handler attach callback, acpi_cmos_rtc_attach(),
but if the ACPI namespace does not contain a CMOS RTC device object,
the CMOS RTC address space handler installation is taken care of the
ACPI TAD (Timer and Alarm Device) driver.
This is not particularly straightforward and can be avoided by adding
the ACPI TAD device ID to the CMOS RTC ACPI scan handler which will
cause it to create a platform device for ACPI TAD after installing
the CMOS RTC address space handler. One related detail that needs to
be taken care of, though, is that the creation of an ACPI TAD platform
device should not cause cmos_rtc_platform_device_present to be set,
since this may cause add_rtc_cmos() to suppress the creation of a
fallback CMOS RTC platform device which may not be the right thing
to do (for instance, due to the fact that the ACPI TAD driver is
missing an RTC class device interface).
After doing the above, the CMOS RTC address space handler installation
and removal can be dropped from the ACPI TAD driver (which allows it to
be simplified quite a bit), acpi_remove_cmos_rtc_space_handler() can
be dropped and acpi_install_cmos_rtc_space_handler() can be made static.
Update the code as per the above.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/23028644.EfDdHjke4D@rafael.j.wysocki
e8d1eb6519