cxl/region: Prepare the decoder match range helper for reuse

stable inclusion
from stable-v6.6.2
commit c4255b9b0a12c81d573bf7362c9e6446e04d2f77
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8IW7G

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c4255b9b0a12c81d573bf7362c9e6446e04d2f77



--------------------------------

[ Upstream commit 1110581412c7a223439bb3ecdcdd9f4432e08231 ]

match_decoder_by_range() and decoder_match_range() both determine
if an HPA range matches a decoder. The first does it for root
decoders and the second one operates on switch decoders.

Tidy these up with clear naming and make the switch helper more
like the root decoder helper in style and functionality. Make it
take the actual range, rather than an endpoint decoder from which
it extracts the range. Require an exact match on switch decoders,
because unlike a root decoder that maps an entire region, Linux
only supports 1:1 mapping of switch to endpoint decoders. Note that
root-decoders are a super-set of switch-decoders and the range they
cover is a super-set of a region, hence the use of range_contains() for
that case.

Aside from aesthetics and maintainability, this is in preparation
for reuse.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Jim Harris <jim.harris@samsung.com>
Link: https://lore.kernel.org/r/011b1f498e1758bb8df17c5951be00bd8d489e3b.1698263080.git.alison.schofield@intel.com


[djbw: fixup root decoder vs switch decoder range checks]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Stable-dep-of: 0cf36a85c140 ("cxl/region: Use cxl_calc_interleave_pos() for auto-discovery")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>