diff --git a/src/acpi/acpi.c b/src/acpi/acpi.c
index 13728c904d..94b6309261 100644
--- a/src/acpi/acpi.c
+++ b/src/acpi/acpi.c
@@ -287,17 +287,14 @@ static void acpi_create_tpm2(acpi_header_t *header, void *unused)
 	tpm2->platform_class = 0;
 
 	if (CONFIG(AMD_CRB_FTPM) && crb_tpm_is_active()) {
-		/* Must be set to 2 for AMD fTPM Support */
 		tpm2->control_area = crb_tpm_base_address() + 0x40;
-		tpm2->start_method = 2;
+		tpm2->start_method = ACPI_TPM2_SM_ACPI_START;
 	} else if (CONFIG(CRB_TPM) && crb_tpm_is_active()) {
-		/* Must be set to 7 for CRB Support */
 		tpm2->control_area = crb_tpm_base_address() + 0x40;
-		tpm2->start_method = 7;
+		tpm2->start_method = ACPI_TPM2_SM_CRB;
 	} else {
-		/* Must be set to 0 for FIFO interface support */
 		tpm2->control_area = 0;
-		tpm2->start_method = 6;
+		tpm2->start_method = ACPI_TPM2_SM_MMIO_TIS;
 	}
 	memset(tpm2->msp, 0, sizeof(tpm2->msp));
 
diff --git a/src/include/acpi/acpi.h b/src/include/acpi/acpi.h
index 87c99a1eb3..ac00050031 100644
--- a/src/include/acpi/acpi.h
+++ b/src/include/acpi/acpi.h
@@ -243,6 +243,20 @@ typedef struct acpi_tcpa {
 	u64 lasa;
 } __packed acpi_tcpa_t;
 
+/* TCG ACPI Specification "Table 8: Start Method values for ACPI table for TPM 2.0" */
+enum acpi_tpm2_start_methods {
+	ACPI_TPM2_SM_NOT_ALLOWED = 0,
+	ACPI_TPM2_SM_LEGACY,
+	ACPI_TPM2_SM_ACPI_START,
+	ACPI_TPM2_SM_MMIO_TIS = 6,
+	ACPI_TPM2_SM_CRB,
+	ACPI_TPM2_SM_CRB_AND_ACPI_START,
+	ACPI_TPM2_SM_CRB_AND_ARM_SECURE_MONITOR = 11,
+	ACPI_TPM2_SM_FIFO_I2C,
+	ACPI_TPM2_SM_RESERVED_MMIO0,
+	ACPI_TPM2_SM_RESERVED_MMIO1,
+};
+
 typedef struct acpi_tpm2 {
 	acpi_header_t header;
 	u16 platform_class;