crypto: ccp - Avoid discarding errors in psp_send_platform_access_msg()

Errors can potentially occur in the "processing" of PSP commands or
commands can be processed successfully but still return an error code in
the header.

This second case was being discarded because PSP communication worked but
the command returned an error code in the payload header.

Capture both cases and return them to the caller as -EIO for the caller
to investigate. The caller can detect the latter by looking at
`req->header->status`.

Reported-and-tested-by: Tim Van Patten <timvp@google.com>
Fixes: 7ccc4f4e2e50 ("crypto: ccp - Add support for an interface for platform features")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto: ccp - Validate that platform access mailbox registers are declared

Some platforms might support platform access doorbell but not mailbox.
Add an extra guard to ensure this doesn't cause accesses to wrong ranges
if a consumer calls psp_send_platform_access_msg().

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

crypto: ccp - Use lower 8 bytes to communicate with doorbell command register

Unlike other command registers used by the PSP, only the lower 8 bytes are
used for communication for both command and status of the command.

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>

crypto: ccp - Return doorbell status code as an argument

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>

crypto: ccp - Bump up doorbell debug message to error

This is helpful not just for debugging problems, but also for investigating
captured logs later on.

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

crypto: ccp - Drop extra doorbell checks

The doorbell register set used for I2C arbitration is dedicated for this
purpose and there is no need to utilize other safety checks the platform
access register set uses.

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>

crypto: ccp - Add support for ringing a platform doorbell

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>

crypto: ccp - Add support for an interface for platform features

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>