tpm: Add dummy _DSM to make Bitlocker happy.

Change-Id: Ieb6f70f5b2863336bd6143b2dfbb1d67c4c26109
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/10323
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/drivers/pc80/tpm/acpi/tpm.asl

@@ -101,4 +101,96 @@ Device (TPM)
 			Return (RBUF)
 		}
 	}
+
+	/* Dummy _DSM to make Bitlocker work.  */
+	Method (_DSM, 4, Serialized)
+	{
+		/* Physical presence interface.
+		   This is used to submit commands like "Clear TPM" to
+		   be run at next reboot provided that user confirms them.
+		   Spec allows user to cancel all commands and/or
+		   configure BIOS to reject commands. So we pretend that
+		   user did just this: cancelled everything. If user
+		   really wants to clear TPM the only option now is to do it manually
+		   in payload.
+		 */
+		If (LEqual (Arg0, ToUUID ("3dddfaa6-361b-4eb4-a424-8d10089d1653")))
+		{
+			If (LEqual (Arg2, 0))
+			{
+				/* Functions 1-8.  */
+				Return (Buffer (2) { 0xFF, 0x01 })
+			}
+
+			/* Interface version: 1.2  */
+			If (LEqual (Arg2, 1))
+			{
+				Return ("1.2")
+			}
+
+			/* Submit operations: drop on the floor and return success.  */
+			If (LEqual (Arg2, 2))
+			{
+				Return (0x00)
+			}
+
+			/* Pending operation: none.  */
+			If (LEqual (Arg2, 3))
+			{
+				Return (Package (2) { 0, 0 })
+			}
+
+			/* Pre-OS transition method: reboot. */
+			If (LEqual (Arg2, 4))
+			{
+				Return (2)
+			}
+
+			/* Operation response: no operation executed.  */
+			If (LEqual (Arg2, 5))
+			{
+				Return (Package (3) { 0, 0, 0 })
+			}
+
+			/* Set preffered user language: deprecated and must return 3 aka "not implemented".  */
+			If (LEqual (Arg2, 6))
+			{
+				Return (3)
+			}
+
+			/* Submit operations: deny.  */
+			If (LEqual (Arg2, 7))
+			{
+				Return (3)
+			}
+
+			/* All actions are forbidden.  */
+			If (LEqual (Arg2, 8))
+			{
+				Return (1)
+			}
+
+			Return (1)
+		}
+
+		/* Memory clearing on boot: just a dummy.  */
+		If (LEqual (Arg0, ToUUID("376054ed-cc13-4675-901c-4756d7f2d45d")))
+		{
+			If (LEqual (Arg2, 0))
+			{
+				/* Function 1.  */
+				Return (Buffer (1) { 3 })
+			}
+
+			/* Just return success.  */
+			If (LEqual (Arg2, 1))
+			{
+				Return (0)
+			}
+
+			Return (1)
+		}
+
+		Return (Buffer (1) { 0 })
+	}
 }