[RFC v2 1/5] tpm_crb: Add register definitions of TPM CRB chunking fields

[Arun Menon]

Post-quantum cryptographic (PQC) algorithms can require buffer sizes that
exceed the physical capacity of the TPM's Command/Response Buffer (CRB).
To support these larger payloads, the TPM 2.0 CRB specification [1]
allows for data chunking when the physical MMIO window is smaller than
the required buffer size.

To support this protocol, the TPM driver must be able to detect the
chunking capability, and signal the backend using specific start
method flags, also known as the control area start register bits.

As per sections 6.4.2.2 and 6.5.3.9 of the specification document [1]
Add 2 new bit flags to the existing enum crb_start and add the
capability bit.
- CRB_INTF_CAP_CRB_CHUNK: A capability bit used to detect if the backend
  supports chunking.
- CRB_START_NEXT_CHUNK: A control bit to signal the TPM to consume the
  current command buffer, or to get the next chunk from the response
  buffer.
- CRB_START_RESP_RETRY: A control bit to signal retransmission of a
  response buffer.

[1] https://trustedcomputinggroup.org/wp-content/uploads/PC-Client-Specific-Platform-TPM-Profile-for-TPM-2p0-v1p07_rc1_121225.pdf

Signed-off-by: Arun Menon <armenon@xxxxxxxxxx>
---
 drivers/char/tpm/tpm_crb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 6c25305c256ef..67c0061d4cab7 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -56,12 +56,18 @@ enum crb_ctrl_sts {
 
 enum crb_start {
 	CRB_START_INVOKE	= BIT(0),
+	CRB_START_RESP_RETRY = BIT(1),
+	CRB_START_NEXT_CHUNK = BIT(2),
 };
 
 enum crb_cancel {
 	CRB_CANCEL_INVOKE	= BIT(0),
 };
 
+enum crb_intf {
+	CRB_INTF_CAP_CRB_CHUNK = BIT(10),
+};
+
 struct crb_regs_head {
 	u32 loc_state;
 	u32 reserved1;
-- 
2.53.0