EDAC/amd64: Find Chip Select memory size using Address Mask

EDAC/amd64: Find Chip Select memory size using Address Mask

Chip Select memory size reporting on AMD Family 17h was recently fixed
in order to account for interleaving. However, the current method is not
robust.

The Chip Select Address Mask can be used to find the memory size. There
are a couple of cases.

1) For single-rank and dual-rank non-interleaved, use the address mask
plus 1 as the size.

2) For dual-rank interleaved, do #1 but "de-interleave" the address mask
first.

Always "de-interleave" the address mask in order to simplify the code
flow. Bit mask manipulation is necessary to check for interleaving, so
just go ahead and do the de-interleaving. In the non-interleaved case,
the original and de-interleaved address masks will be the same.

To de-interleave the mask, count the number of zero bits in the middle
of the mask and swap them with the most significant bits.

For example,
Original=0xFFFF9FE, De-interleaved=0x3FFFFFE

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20190821235938.118710-5-Yazen.Ghannam@amd.com