security/tpm: Add vendor-specific tis functions to read/write TPM regs

In order to abstract bus-specific logic from TPM logic, the prototype
for two vendor-specific tis functions are added in this
patch. tis_vendor_read() can be used to read directly from TPM
registers, and tis_vendor_write() can be used to write directly to TPM
registers.

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I939cf5b6620b6f5f6d454c53fcaf37c153702acc
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62058
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/security/tpm/tis.h

@@ -5,6 +5,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <types.h>
 
 enum tis_access {
 	TPM_ACCESS_VALID = (1 << 7),
@@ -84,4 +85,31 @@ int tis_sendrecv(const u8 *sendbuf, size_t send_size, u8 *recvbuf,
  */
 int tis_plat_irq_status(void);
 
+/*
+ * tis_vendor_write()
+ *
+ * Vendor-specific function to send the requested data to the TPM.
+ *
+ * @addr - address of the register to write to
+ * @sendbuf - buffer of the data to send
+ * @send_size - size of the data to send
+ *
+ * Returns CB_SUCCESS 0 on success, CB_ERR on failure.
+ */
+cb_err_t tis_vendor_write(unsigned int addr, const void *sendbuf, size_t send_size);
+
+/*
+ * tis_vendor_read()
+ *
+ * Vendor-specific function to read the requested data from the TPM.
+ *
+ * @addr - address of the register to read from
+ * @recvbuf - buffer of the data to read
+ * @recv_size - size of the output buffer
+ *
+ * Returns CB_SUCCESS on success or -1 on failure.
+ */
+cb_err_t tis_vendor_read(unsigned int addr, void *recvbuf, size_t recv_size);
+
+
 #endif /* TIS_H_ */