sb/intel/bd82x6x: Correct xHCI sleep workaround

The S3/S4 workaround is specific to Panther Point stepping A0, and it is
wrongly implemented. Rewrite the whole function as per reference code.
Since this runs in SMM, be overly cautious and double-check everything.

Do not rely on GNVS to determine if xHCI is enabled. Instead, check
whether the corresponding bit in the Function Disable register is set.
Only Panther Point has xHCI, so exit early if this is not the case.

Change-Id: Iabce6c52fac781dc694f5b589fab2e9fe438f3f5
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49130
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

0 files changed, 0 insertions, 0 deletions