Currently the PSP semaphore communication base address is discovered
by using an MSR that is not architecturally guaranteed for future
platforms.  Also the mailbox that is utilized for communication with
the PSP may have other consumers in the kernel, so it's better to
make all communication go through a single driver.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Mark Hasemeyer <markhas@chromium.org>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Mark Hasemeyer <markhas@chromium.org>
Acked-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

If the doorbell failed to ring we return -EIO, but the caller can't
determine why it failed.  Pass the reason for the failure in an
argument for caller to investigate.

Suggested-by: Mark Hasemeyer <markhas@chromium.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Mark Hasemeyer <markhas@chromium.org>
Tested-by: Mark Hasemeyer <markhas@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Some platforms support using a doorbell to communicate. Export
this feature for other drivers to utilize as well.

Link: https://lore.kernel.org/linux-i2c/20220916131854.687371-3-jsd@semihalf.com/
Suggested-by: Jan Dabros <jsd@semihalf.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Some platforms with a PSP support an interface for features that
interact directly with the PSP instead of through a SEV or TEE
environment.

Initialize this interface so that other drivers can consume it.
These drivers may either be subdrivers for the ccp module or
external modules.  For external modules, export a symbol for them
to utilize.

Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>