feat(cpufeat): extend check_feature() to deal with min/max

So far the check_feature() function compares the subfield of a CPU ID
register against 0, to learn if a feature is enabled or not.
This is problematic for checks that require a certain revision of a
feature, so we should check against a minimum version number instead.
On top of that we might need to add code to support newer versions of a
feature, so we should be alerted if new hardware introduces a higher

Extend the check_feature() function to take two extra arguments: the
minimum version, and the greatest currently known number.
Then make sure that the CPU ID field is in this range.

Change-Id: I425b68535a2ba9eafd31854e74d142183b521cd5
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
1 file changed