The TPM interface (tpm_tis) needs to be explicitly enabled via 
./configure --enable-tpm. This patch also restricts the building of the
TPM support to i386 and x86_64 targets since both backends I know
of, the Xen backend and the libtpms-based backend, will likely only
be available for these targets, at least initially. The list can be
easily extend. I am trying to prevent that one will end up with
support for a frontend but no available backend.

v3:
 - fixed and moved hunks in Makefile.target into right place

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

Index:qemu/Makefile.target
===================================================================
---
 Makefile.target |    1 +
 configure       |   20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

Index: qemu-git/Makefile.target
===================================================================
--- qemu-git.orig/Makefile.target
+++ qemu-git/Makefile.target
@@ -226,6 +226,7 @@ obj-i386-y += device-hotplug.o pci-hotpl
 obj-i386-y += debugcon.o multiboot.o
 obj-i386-y += pc_piix.o kvmclock.o
 obj-i386-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
+obj-i386-$(CONFIG_TPM) += tpm_tis.o
 
 # shared objects
 obj-ppc-y = ppc.o
Index: qemu-git/configure
===================================================================
--- qemu-git.orig/configure
+++ qemu-git/configure
@@ -178,6 +178,7 @@ rbd=""
 smartcard=""
 smartcard_nss=""
 opengl=""
+tpm="no"
 
 # parse CC options first
 for opt do
@@ -713,6 +714,8 @@ for opt do
   ;;
   --kerneldir=*) kerneldir="$optarg"
   ;;
+  --enable-tpm) tpm="yes"
+  ;;
   --with-pkgversion=*) pkgversion=" ($optarg)"
   ;;
   --disable-docs) docs="no"
@@ -945,6 +948,7 @@ echo "  --disable-smartcard      disable
 echo "  --enable-smartcard       enable smartcard support"
 echo "  --disable-smartcard-nss  disable smartcard nss support"
 echo "  --enable-smartcard-nss   enable smartcard nss support"
+echo "  --enable-tpm             enables an emulated TPM"
 echo ""
 echo "NOTE: The object files are built at the place where configure is launched"
 exit 1
@@ -2623,6 +2627,7 @@ echo "rbd support       $rbd"
 echo "xfsctl support    $xfs"
 echo "nss used          $smartcard_nss"
 echo "OpenGL support    $opengl"
+echo "TPM support       $tpm"
 
 if test $sdl_too_old = "yes"; then
 echo "-> Your SDL version is too old - please upgrade to have SDL support"
@@ -3433,6 +3438,21 @@ if test "$gprof" = "yes" ; then
   fi
 fi
 
+if test "$tpm" = "yes"; then
+  has_tpm=0
+  if test "$target_softmmu" = "yes" ; then
+    case "$TARGET_BASE_ARCH" in
+    i386)
+      has_tpm=1
+    ;;
+    esac
+  fi
+
+  if test "$has_tpm" = "1"; then
+      echo "CONFIG_TPM=y" >> $config_host_mak
+  fi
+fi
+
 linker_script="-Wl,-T../config-host.ld -Wl,-T,\$(SRC_PATH)/\$(ARCH).ld"
 if test "$target_linux_user" = "yes" -o "$target_bsd_user" = "yes" ; then
   case "$ARCH" in