tpm: reorganize headers and split hardware part

The TPM subsystem does not have a full front-end/back-end separation.
The sole available backend, tpm_passthrough, depends on the data
structures of the sole available frontend, tpm_tis.

However, we can at least try to split the user interface (tpm.c) from the
implementation (hw/tpm).  The patches makes tpm.c not include tpm_int.h,
which is shared between tpm_tis.c and tpm_passthrough.c; instead it
moves more stuff to tpm_backend.h.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

5 files changed, 1643 insertions, 0 deletions

diff --git a/hw/tpm/Makefile.objs b/hw/tpm/Makefile.objs
new file mode 100644
index 0000000..99f5983
--- /dev/null
+++ b/hw/tpm/Makefile.objs
@@ -0,0 +1,2 @@
+common-obj-$(CONFIG_TPM_TIS) += tpm_tis.o
+common-obj-$(CONFIG_TPM_PASSTHROUGH) += tpm_passthrough.o
diff --git a/hw/tpm/tpm_int.h b/hw/tpm/tpm_int.h
new file mode 100644
index 0000000..08f87cb
--- /dev/null
+++ b/hw/tpm/tpm_int.h
@@ -0,0 +1,60 @@
+/*
+ * TPM configuration
+ *
+ * Copyright (C) 2011-2013 IBM Corporation
+ *
+ * Authors:
+ *  Stefan Berger    <stefanb@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#ifndef TPM_TPM_INT_H
+#define TPM_TPM_INT_H
+
+#include "exec/memory.h"
+#include "tpm_tis.h"
+
+/* overall state of the TPM interface */
+struct TPMState {
+    ISADevice busdev;
+    MemoryRegion mmio;
+
+    union {
+        TPMTISEmuState tis;
+    } s;
+
+    uint8_t     locty_number;
+    TPMLocality *locty_data;
+
+    char *backend;
+    TPMBackend *be_driver;
+};
+
+#define TPM(obj) OBJECT_CHECK(TPMState, (obj), TYPE_TPM_TIS)
+
+struct tpm_req_hdr {
+    uint16_t tag;
+    uint32_t len;
+    uint32_t ordinal;
+} QEMU_PACKED;
+
+struct tpm_resp_hdr {
+    uint16_t tag;
+    uint32_t len;
+    uint32_t errcode;
+} QEMU_PACKED;
+
+#define TPM_TAG_RQU_COMMAND       0xc1
+#define TPM_TAG_RQU_AUTH1_COMMAND 0xc2
+#define TPM_TAG_RQU_AUTH2_COMMAND 0xc3
+
+#define TPM_TAG_RSP_COMMAND       0xc4
+#define TPM_TAG_RSP_AUTH1_COMMAND 0xc5
+#define TPM_TAG_RSP_AUTH2_COMMAND 0xc6
+
+#define TPM_FAIL                  9
+
+#define TPM_ORD_GetTicks          0xf1
+
+#endif /* TPM_TPM_INT_H */
diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c
new file mode 100644
index 0000000..5781277
--- /dev/null
+++ b/hw/tpm/tpm_passthrough.c
@@ -0,0 +1,576 @@
+/*
+ *  passthrough TPM driver
+ *
+ *  Copyright (c) 2010 - 2013 IBM Corporation
+ *  Authors:
+ *    Stefan Berger <stefanb@us.ibm.com>
+ *
+ *  Copyright (C) 2011 IAIK, Graz University of Technology
+ *    Author: Andreas Niederl
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#include <dirent.h>
+
+#include "qemu-common.h"
+#include "qapi/error.h"
+#include "qemu/sockets.h"
+#include "backends/tpm.h"
+#include "tpm_int.h"
+#include "hw/hw.h"
+#include "hw/i386/pc.h"
+#include "sysemu/tpm_backend_int.h"
+#include "tpm_tis.h"
+
+/* #define DEBUG_TPM */
+
+#ifdef DEBUG_TPM
+#define DPRINTF(fmt, ...) \
+    do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+#define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
+#define TPM_PASSTHROUGH(obj) \
+    OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
+
+static const TPMDriverOps tpm_passthrough_driver;
+
+/* data structures */
+typedef struct TPMPassthruThreadParams {
+    TPMState *tpm_state;
+
+    TPMRecvDataCB *recv_data_callback;
+    TPMBackend *tb;
+} TPMPassthruThreadParams;
+
+struct TPMPassthruState {
+    TPMBackend parent;
+
+    TPMBackendThread tbt;
+
+    TPMPassthruThreadParams tpm_thread_params;
+
+    char *tpm_dev;
+    int tpm_fd;
+    bool tpm_executing;
+    bool tpm_op_canceled;
+    int cancel_fd;
+    bool had_startup_error;
+};
+
+typedef struct TPMPassthruState TPMPassthruState;
+
+#define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
+
+/* functions */
+
+static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
+
+static int tpm_passthrough_unix_write(int fd, const uint8_t *buf, uint32_t len)
+{
+    return send_all(fd, buf, len);
+}
+
+static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
+{
+    return recv_all(fd, buf, len, true);
+}
+
+static uint32_t tpm_passthrough_get_size_from_buffer(const uint8_t *buf)
+{
+    struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)buf;
+
+    return be32_to_cpu(resp->len);
+}
+
+/*
+ * Write an error message in the given output buffer.
+ */
+static void tpm_write_fatal_error_response(uint8_t *out, uint32_t out_len)
+{
+    if (out_len >= sizeof(struct tpm_resp_hdr)) {
+        struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)out;
+
+        resp->tag = cpu_to_be16(TPM_TAG_RSP_COMMAND);
+        resp->len = cpu_to_be32(sizeof(struct tpm_resp_hdr));
+        resp->errcode = cpu_to_be32(TPM_FAIL);
+    }
+}
+
+static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
+                                        const uint8_t *in, uint32_t in_len,
+                                        uint8_t *out, uint32_t out_len)
+{
+    int ret;
+
+    tpm_pt->tpm_op_canceled = false;
+    tpm_pt->tpm_executing = true;
+
+    ret = tpm_passthrough_unix_write(tpm_pt->tpm_fd, in, in_len);
+    if (ret != in_len) {
+        if (!tpm_pt->tpm_op_canceled ||
+            (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
+            error_report("tpm_passthrough: error while transmitting data "
+                         "to TPM: %s (%i)\n",
+                         strerror(errno), errno);
+        }
+        goto err_exit;
+    }
+
+    tpm_pt->tpm_executing = false;
+
+    ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
+    if (ret < 0) {
+        if (!tpm_pt->tpm_op_canceled ||
+            (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {
+            error_report("tpm_passthrough: error while reading data from "
+                         "TPM: %s (%i)\n",
+                         strerror(errno), errno);
+        }
+    } else if (ret < sizeof(struct tpm_resp_hdr) ||
+               tpm_passthrough_get_size_from_buffer(out) != ret) {
+        ret = -1;
+        error_report("tpm_passthrough: received invalid response "
+                     "packet from TPM\n");
+    }
+
+err_exit:
+    if (ret < 0) {
+        tpm_write_fatal_error_response(out, out_len);
+    }
+
+    tpm_pt->tpm_executing = false;
+
+    return ret;
+}
+
+static int tpm_passthrough_unix_transfer(TPMPassthruState *tpm_pt,
+                                         const TPMLocality *locty_data)
+{
+    return tpm_passthrough_unix_tx_bufs(tpm_pt,
+                                        locty_data->w_buffer.buffer,
+                                        locty_data->w_offset,
+                                        locty_data->r_buffer.buffer,
+                                        locty_data->r_buffer.size);
+}
+
+static void tpm_passthrough_worker_thread(gpointer data,
+                                          gpointer user_data)
+{
+    TPMPassthruThreadParams *thr_parms = user_data;
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(thr_parms->tb);
+    TPMBackendCmd cmd = (TPMBackendCmd)data;
+
+    DPRINTF("tpm_passthrough: processing command type %d\n", cmd);
+
+    switch (cmd) {
+    case TPM_BACKEND_CMD_PROCESS_CMD:
+        tpm_passthrough_unix_transfer(tpm_pt,
+                                      thr_parms->tpm_state->locty_data);
+
+        thr_parms->recv_data_callback(thr_parms->tpm_state,
+                                      thr_parms->tpm_state->locty_number);
+        break;
+    case TPM_BACKEND_CMD_INIT:
+    case TPM_BACKEND_CMD_END:
+    case TPM_BACKEND_CMD_TPM_RESET:
+        /* nothing to do */
+        break;
+    }
+}
+
+/*
+ * Start the TPM (thread). If it had been started before, then terminate
+ * and start it again.
+ */
+static int tpm_passthrough_startup_tpm(TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+
+    /* terminate a running TPM */
+    tpm_backend_thread_end(&tpm_pt->tbt);
+
+    tpm_backend_thread_create(&tpm_pt->tbt,
+                              tpm_passthrough_worker_thread,
+                              &tpm_pt->tpm_thread_params);
+
+    return 0;
+}
+
+static void tpm_passthrough_reset(TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+
+    DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");
+
+    tpm_passthrough_cancel_cmd(tb);
+
+    tpm_backend_thread_end(&tpm_pt->tbt);
+
+    tpm_pt->had_startup_error = false;
+}
+
+static int tpm_passthrough_init(TPMBackend *tb, TPMState *s,
+                                TPMRecvDataCB *recv_data_cb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+
+    tpm_pt->tpm_thread_params.tpm_state = s;
+    tpm_pt->tpm_thread_params.recv_data_callback = recv_data_cb;
+    tpm_pt->tpm_thread_params.tb = tb;
+
+    return 0;
+}
+
+static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
+{
+    return false;
+}
+
+static bool tpm_passthrough_get_startup_error(TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+
+    return tpm_pt->had_startup_error;
+}
+
+static size_t tpm_passthrough_realloc_buffer(TPMSizedBuffer *sb)
+{
+    size_t wanted_size = 4096; /* Linux tpm.c buffer size */
+
+    if (sb->size != wanted_size) {
+        sb->buffer = g_realloc(sb->buffer, wanted_size);
+        sb->size = wanted_size;
+    }
+    return sb->size;
+}
+
+static void tpm_passthrough_deliver_request(TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+
+    tpm_backend_thread_deliver_request(&tpm_pt->tbt);
+}
+
+static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+    int n;
+
+    /*
+     * As of Linux 3.7 the tpm_tis driver does not properly cancel
+     * commands on all TPM manufacturers' TPMs.
+     * Only cancel if we're busy so we don't cancel someone else's
+     * command, e.g., a command executed on the host.
+     */
+    if (tpm_pt->tpm_executing) {
+        if (tpm_pt->cancel_fd >= 0) {
+            n = write(tpm_pt->cancel_fd, "-", 1);
+            if (n != 1) {
+                error_report("Canceling TPM command failed: %s\n",
+                             strerror(errno));
+            } else {
+                tpm_pt->tpm_op_canceled = true;
+            }
+        } else {
+            error_report("Cannot cancel TPM command due to missing "
+                         "TPM sysfs cancel entry");
+        }
+    }
+}
+
+static const char *tpm_passthrough_create_desc(void)
+{
+    return "Passthrough TPM backend driver";
+}
+
+/*
+ * A basic test of a TPM device. We expect a well formatted response header
+ * (error response is fine) within one second.
+ */
+static int tpm_passthrough_test_tpmdev(int fd)
+{
+    struct tpm_req_hdr req = {
+        .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
+        .len = cpu_to_be32(sizeof(req)),
+        .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
+    };
+    struct tpm_resp_hdr *resp;
+    fd_set readfds;
+    int n;
+    struct timeval tv = {
+        .tv_sec = 1,
+        .tv_usec = 0,
+    };
+    unsigned char buf[1024];
+
+    n = write(fd, &req, sizeof(req));
+    if (n < 0) {
+        return errno;
+    }
+    if (n != sizeof(req)) {
+        return EFAULT;
+    }
+
+    FD_ZERO(&readfds);
+    FD_SET(fd, &readfds);
+
+    /* wait for a second */
+    n = select(fd + 1, &readfds, NULL, NULL, &tv);
+    if (n != 1) {
+        return errno;
+    }
+
+    n = read(fd, &buf, sizeof(buf));
+    if (n < sizeof(struct tpm_resp_hdr)) {
+        return EFAULT;
+    }
+
+    resp = (struct tpm_resp_hdr *)buf;
+    /* check the header */
+    if (be16_to_cpu(resp->tag) != TPM_TAG_RSP_COMMAND ||
+        be32_to_cpu(resp->len) != n) {
+        return EBADMSG;
+    }
+
+    return 0;
+}
+
+/*
+ * Check whether the given base path, e.g.,  /sys/class/misc/tpm0/device,
+ * is the sysfs directory of a TPM. A TPM sysfs directory should be uniquely
+ * recognizable by the file entries 'pcrs' and 'cancel'.
+ * Upon success 'true' is returned and the basebath buffer has '/cancel'
+ * appended.
+ */
+static bool tpm_passthrough_check_sysfs_cancel(char *basepath, size_t bufsz)
+{
+    char path[PATH_MAX];
+    struct stat statbuf;
+
+    snprintf(path, sizeof(path), "%s/pcrs", basepath);
+    if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
+        return false;
+    }
+
+    snprintf(path, sizeof(path), "%s/cancel", basepath);
+    if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
+        return false;
+    }
+
+    strncpy(basepath, path, bufsz);
+
+    return true;
+}
+
+/*
+ * Unless path or file descriptor set has been provided by user,
+ * determine the sysfs cancel file following kernel documentation
+ * in Documentation/ABI/stable/sysfs-class-tpm.
+ */
+static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
+{
+    int fd = -1;
+    unsigned int idx;
+    DIR *pnp_dir;
+    char path[PATH_MAX];
+    struct dirent entry, *result;
+    int len;
+
+    if (tb->cancel_path) {
+        fd = qemu_open(tb->cancel_path, O_WRONLY);
+        if (fd < 0) {
+            error_report("Could not open TPM cancel path : %s",
+                         strerror(errno));
+        }
+        return fd;
+    }
+
+    snprintf(path, sizeof(path), "/sys/class/misc");
+    pnp_dir = opendir(path);
+    if (pnp_dir != NULL) {
+        while (readdir_r(pnp_dir, &entry, &result) == 0 &&
+               result != NULL) {
+            /*
+             * only allow /sys/class/misc/tpm%u type of paths
+             */
+            if (sscanf(entry.d_name, "tpm%u%n", &idx, &len) < 1 ||
+                len <= strlen("tpm") ||
+                len != strlen(entry.d_name)) {
+                continue;
+            }
+
+            snprintf(path, sizeof(path), "/sys/class/misc/%s/device",
+                     entry.d_name);
+            if (!tpm_passthrough_check_sysfs_cancel(path, sizeof(path))) {
+                continue;
+            }
+
+            fd = qemu_open(path, O_WRONLY);
+            break;
+        }
+        closedir(pnp_dir);
+    }
+
+    if (fd >= 0) {
+        tb->cancel_path = g_strdup(path);
+    }
+
+    return fd;
+}
+
+static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+    const char *value;
+
+    value = qemu_opt_get(opts, "cancel-path");
+    if (value) {
+        tb->cancel_path = g_strdup(value);
+    }
+
+    value = qemu_opt_get(opts, "path");
+    if (!value) {
+        value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
+    }
+
+    tpm_pt->tpm_dev = g_strdup(value);
+
+    tb->path = g_strdup(tpm_pt->tpm_dev);
+
+    tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
+    if (tpm_pt->tpm_fd < 0) {
+        error_report("Cannot access TPM device using '%s': %s\n",
+                     tpm_pt->tpm_dev, strerror(errno));
+        goto err_free_parameters;
+    }
+
+    if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
+        error_report("'%s' is not a TPM device.\n",
+                     tpm_pt->tpm_dev);
+        goto err_close_tpmdev;
+    }
+
+    return 0;
+
+ err_close_tpmdev:
+    qemu_close(tpm_pt->tpm_fd);
+    tpm_pt->tpm_fd = -1;
+
+ err_free_parameters:
+    g_free(tb->path);
+    tb->path = NULL;
+
+    g_free(tpm_pt->tpm_dev);
+    tpm_pt->tpm_dev = NULL;
+
+    return 1;
+}
+
+static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
+{
+    Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
+    TPMBackend *tb = TPM_BACKEND(obj);
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+
+    tb->id = g_strdup(id);
+    /* let frontend set the fe_model to proper value */
+    tb->fe_model = -1;
+
+    tb->ops = &tpm_passthrough_driver;
+
+    if (tpm_passthrough_handle_device_opts(opts, tb)) {
+        goto err_exit;
+    }
+
+    tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
+    if (tpm_pt->cancel_fd < 0) {
+        goto err_exit;
+    }
+
+    return tb;
+
+err_exit:
+    g_free(tb->id);
+
+    return NULL;
+}
+
+static void tpm_passthrough_destroy(TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+
+    tpm_passthrough_cancel_cmd(tb);
+
+    tpm_backend_thread_end(&tpm_pt->tbt);
+
+    qemu_close(tpm_pt->tpm_fd);
+    qemu_close(tpm_pt->cancel_fd);
+
+    g_free(tb->id);
+    g_free(tb->path);
+    g_free(tb->cancel_path);
+    g_free(tpm_pt->tpm_dev);
+}
+
+static const TPMDriverOps tpm_passthrough_driver = {
+    .type                     = TPM_TYPE_PASSTHROUGH,
+    .desc                     = tpm_passthrough_create_desc,
+    .create                   = tpm_passthrough_create,
+    .destroy                  = tpm_passthrough_destroy,
+    .init                     = tpm_passthrough_init,
+    .startup_tpm              = tpm_passthrough_startup_tpm,
+    .realloc_buffer           = tpm_passthrough_realloc_buffer,
+    .reset                    = tpm_passthrough_reset,
+    .had_startup_error        = tpm_passthrough_get_startup_error,
+    .deliver_request          = tpm_passthrough_deliver_request,
+    .cancel_cmd               = tpm_passthrough_cancel_cmd,
+    .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
+};
+
+static void tpm_passthrough_inst_init(Object *obj)
+{
+}
+
+static void tpm_passthrough_inst_finalize(Object *obj)
+{
+}
+
+static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
+{
+    TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
+
+    tbc->ops = &tpm_passthrough_driver;
+}
+
+static const TypeInfo tpm_passthrough_info = {
+    .name = TYPE_TPM_PASSTHROUGH,
+    .parent = TYPE_TPM_BACKEND,
+    .instance_size = sizeof(TPMPassthruState),
+    .class_init = tpm_passthrough_class_init,
+    .instance_init = tpm_passthrough_inst_init,
+    .instance_finalize = tpm_passthrough_inst_finalize,
+};
+
+static void tpm_passthrough_register(void)
+{
+    type_register_static(&tpm_passthrough_info);
+    tpm_register_driver(&tpm_passthrough_driver);
+}
+
+type_init(tpm_passthrough_register)
diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
new file mode 100644
index 0000000..faa3cec
--- /dev/null
+++ b/hw/tpm/tpm_tis.c
@@ -0,0 +1,930 @@
+/*
+ * tpm_tis.c - QEMU's TPM TIS interface emulator
+ *
+ * Copyright (C) 2006,2010-2013 IBM Corporation
+ *
+ * Authors:
+ *  Stefan Berger <stefanb@us.ibm.com>
+ *  David Safford <safford@us.ibm.com>
+ *
+ * Xen 4 support: Andrease Niederl <andreas.niederl@iaik.tugraz.at>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ * Implementation of the TIS interface according to specs found at
+ * http://www.trustedcomputinggroup.org. This implementation currently
+ * supports version 1.21, revision 1.0.
+ * In the developers menu choose the PC Client section then find the TIS
+ * specification.
+ */
+
+#include "backends/tpm.h"
+#include "tpm_int.h"
+#include "block/block.h"
+#include "exec/address-spaces.h"
+#include "hw/hw.h"
+#include "hw/i386/pc.h"
+#include "hw/pci/pci_ids.h"
+#include "tpm_tis.h"
+#include "qemu-common.h"
+
+/*#define DEBUG_TIS */
+
+#ifdef DEBUG_TIS
+#define DPRINTF(fmt, ...) \
+    do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+/* whether the STS interrupt is supported */
+#define RAISE_STS_IRQ
+
+/* tis registers */
+#define TPM_TIS_REG_ACCESS                0x00
+#define TPM_TIS_REG_INT_ENABLE            0x08
+#define TPM_TIS_REG_INT_VECTOR            0x0c
+#define TPM_TIS_REG_INT_STATUS            0x10
+#define TPM_TIS_REG_INTF_CAPABILITY       0x14
+#define TPM_TIS_REG_STS                   0x18
+#define TPM_TIS_REG_DATA_FIFO             0x24
+#define TPM_TIS_REG_DID_VID               0xf00
+#define TPM_TIS_REG_RID                   0xf04
+
+/* vendor-specific registers */
+#define TPM_TIS_REG_DEBUG                 0xf90
+
+#define TPM_TIS_STS_VALID                 (1 << 7)
+#define TPM_TIS_STS_COMMAND_READY         (1 << 6)
+#define TPM_TIS_STS_TPM_GO                (1 << 5)
+#define TPM_TIS_STS_DATA_AVAILABLE        (1 << 4)
+#define TPM_TIS_STS_EXPECT                (1 << 3)
+#define TPM_TIS_STS_RESPONSE_RETRY        (1 << 1)
+
+#define TPM_TIS_BURST_COUNT_SHIFT         8
+#define TPM_TIS_BURST_COUNT(X) \
+    ((X) << TPM_TIS_BURST_COUNT_SHIFT)
+
+#define TPM_TIS_ACCESS_TPM_REG_VALID_STS  (1 << 7)
+#define TPM_TIS_ACCESS_ACTIVE_LOCALITY    (1 << 5)
+#define TPM_TIS_ACCESS_BEEN_SEIZED        (1 << 4)
+#define TPM_TIS_ACCESS_SEIZE              (1 << 3)
+#define TPM_TIS_ACCESS_PENDING_REQUEST    (1 << 2)
+#define TPM_TIS_ACCESS_REQUEST_USE        (1 << 1)
+#define TPM_TIS_ACCESS_TPM_ESTABLISHMENT  (1 << 0)
+
+#define TPM_TIS_INT_ENABLED               (1 << 31)
+#define TPM_TIS_INT_DATA_AVAILABLE        (1 << 0)
+#define TPM_TIS_INT_STS_VALID             (1 << 1)
+#define TPM_TIS_INT_LOCALITY_CHANGED      (1 << 2)
+#define TPM_TIS_INT_COMMAND_READY         (1 << 7)
+
+#define TPM_TIS_INT_POLARITY_MASK         (3 << 3)
+#define TPM_TIS_INT_POLARITY_LOW_LEVEL    (1 << 3)
+
+#ifndef RAISE_STS_IRQ
+
+#define TPM_TIS_INTERRUPTS_SUPPORTED (TPM_TIS_INT_LOCALITY_CHANGED | \
+                                      TPM_TIS_INT_DATA_AVAILABLE   | \
+                                      TPM_TIS_INT_COMMAND_READY)
+
+#else
+
+#define TPM_TIS_INTERRUPTS_SUPPORTED (TPM_TIS_INT_LOCALITY_CHANGED | \
+                                      TPM_TIS_INT_DATA_AVAILABLE   | \
+                                      TPM_TIS_INT_STS_VALID | \
+                                      TPM_TIS_INT_COMMAND_READY)
+
+#endif
+
+#define TPM_TIS_CAP_INTERRUPT_LOW_LEVEL  (1 << 4) /* support is mandatory */
+#define TPM_TIS_CAPABILITIES_SUPPORTED   (TPM_TIS_CAP_INTERRUPT_LOW_LEVEL | \
+                                          TPM_TIS_INTERRUPTS_SUPPORTED)
+
+#define TPM_TIS_TPM_DID       0x0001
+#define TPM_TIS_TPM_VID       PCI_VENDOR_ID_IBM
+#define TPM_TIS_TPM_RID       0x0001
+
+#define TPM_TIS_NO_DATA_BYTE  0xff
+
+/* local prototypes */
+
+static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr addr,
+                                  unsigned size);
+
+/* utility functions */
+
+static uint8_t tpm_tis_locality_from_addr(hwaddr addr)
+{
+    return (uint8_t)((addr >> TPM_TIS_LOCALITY_SHIFT) & 0x7);
+}
+
+static uint32_t tpm_tis_get_size_from_buffer(const TPMSizedBuffer *sb)
+{
+    return be32_to_cpu(*(uint32_t *)&sb->buffer[2]);
+}
+
+static void tpm_tis_show_buffer(const TPMSizedBuffer *sb, const char *string)
+{
+#ifdef DEBUG_TIS
+    uint32_t len, i;
+
+    len = tpm_tis_get_size_from_buffer(sb);
+    DPRINTF("tpm_tis: %s length = %d\n", string, len);
+    for (i = 0; i < len; i++) {
+        if (i && !(i % 16)) {
+            DPRINTF("\n");
+        }
+        DPRINTF("%.2X ", sb->buffer[i]);
+    }
+    DPRINTF("\n");
+#endif
+}
+
+/*
+ * Send a request to the TPM.
+ */
+static void tpm_tis_tpm_send(TPMState *s, uint8_t locty)
+{
+    TPMTISEmuState *tis = &s->s.tis;
+
+    tpm_tis_show_buffer(&tis->loc[locty].w_buffer, "tpm_tis: To TPM");
+
+    s->locty_number = locty;
+    s->locty_data = &tis->loc[locty];
+
+    /*
+     * w_offset serves as length indicator for length of data;
+     * it's reset when the response comes back
+     */
+    tis->loc[locty].state = TPM_TIS_STATE_EXECUTION;
+
+    tpm_backend_deliver_request(s->be_driver);
+}
+
+/* raise an interrupt if allowed */
+static void tpm_tis_raise_irq(TPMState *s, uint8_t locty, uint32_t irqmask)
+{
+    TPMTISEmuState *tis = &s->s.tis;
+
+    if (!TPM_TIS_IS_VALID_LOCTY(locty)) {
+        return;
+    }
+
+    if ((tis->loc[locty].inte & TPM_TIS_INT_ENABLED) &&
+        (tis->loc[locty].inte & irqmask)) {
+        DPRINTF("tpm_tis: Raising IRQ for flag %08x\n", irqmask);
+        qemu_irq_raise(s->s.tis.irq);
+        tis->loc[locty].ints |= irqmask;
+    }
+}
+
+static uint32_t tpm_tis_check_request_use_except(TPMState *s, uint8_t locty)
+{
+    uint8_t l;
+
+    for (l = 0; l < TPM_TIS_NUM_LOCALITIES; l++) {
+        if (l == locty) {
+            continue;
+        }
+        if ((s->s.tis.loc[l].access & TPM_TIS_ACCESS_REQUEST_USE)) {
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+static void tpm_tis_new_active_locality(TPMState *s, uint8_t new_active_locty)
+{
+    TPMTISEmuState *tis = &s->s.tis;
+    bool change = (s->s.tis.active_locty != new_active_locty);
+    bool is_seize;
+    uint8_t mask;
+
+    if (change && TPM_TIS_IS_VALID_LOCTY(s->s.tis.active_locty)) {
+        is_seize = TPM_TIS_IS_VALID_LOCTY(new_active_locty) &&
+                   tis->loc[new_active_locty].access & TPM_TIS_ACCESS_SEIZE;
+
+        if (is_seize) {
+            mask = ~(TPM_TIS_ACCESS_ACTIVE_LOCALITY);
+        } else {
+            mask = ~(TPM_TIS_ACCESS_ACTIVE_LOCALITY|
+                     TPM_TIS_ACCESS_REQUEST_USE);
+        }
+        /* reset flags on the old active locality */
+        tis->loc[s->s.tis.active_locty].access &= mask;
+
+        if (is_seize) {
+            tis->loc[tis->active_locty].access |= TPM_TIS_ACCESS_BEEN_SEIZED;
+        }
+    }
+
+    tis->active_locty = new_active_locty;
+
+    DPRINTF("tpm_tis: Active locality is now %d\n", s->s.tis.active_locty);
+
+    if (TPM_TIS_IS_VALID_LOCTY(new_active_locty)) {
+        /* set flags on the new active locality */
+        tis->loc[new_active_locty].access |= TPM_TIS_ACCESS_ACTIVE_LOCALITY;
+        tis->loc[new_active_locty].access &= ~(TPM_TIS_ACCESS_REQUEST_USE |
+                                               TPM_TIS_ACCESS_SEIZE);
+    }
+
+    if (change) {
+        tpm_tis_raise_irq(s, tis->active_locty, TPM_TIS_INT_LOCALITY_CHANGED);
+    }
+}
+
+/* abort -- this function switches the locality */
+static void tpm_tis_abort(TPMState *s, uint8_t locty)
+{
+    TPMTISEmuState *tis = &s->s.tis;
+
+    tis->loc[locty].r_offset = 0;
+    tis->loc[locty].w_offset = 0;
+
+    DPRINTF("tpm_tis: tis_abort: new active locality is %d\n", tis->next_locty);
+
+    /*
+     * Need to react differently depending on who's aborting now and
+     * which locality will become active afterwards.
+     */
+    if (tis->aborting_locty == tis->next_locty) {
+        tis->loc[tis->aborting_locty].state = TPM_TIS_STATE_READY;
+        tis->loc[tis->aborting_locty].sts = TPM_TIS_STS_COMMAND_READY;
+        tpm_tis_raise_irq(s, tis->aborting_locty, TPM_TIS_INT_COMMAND_READY);
+    }
+
+    /* locality after abort is another one than the current one */
+    tpm_tis_new_active_locality(s, tis->next_locty);
+
+    tis->next_locty = TPM_TIS_NO_LOCALITY;
+    /* nobody's aborting a command anymore */
+    tis->aborting_locty = TPM_TIS_NO_LOCALITY;
+}
+
+/* prepare aborting current command */
+static void tpm_tis_prep_abort(TPMState *s, uint8_t locty, uint8_t newlocty)
+{
+    TPMTISEmuState *tis = &s->s.tis;
+    uint8_t busy_locty;
+
+    tis->aborting_locty = locty;
+    tis->next_locty = newlocty;  /* locality after successful abort */
+
+    /*
+     * only abort a command using an interrupt if currently executing
+     * a command AND if there's a valid connection to the vTPM.
+     */
+    for (busy_locty = 0; busy_locty < TPM_TIS_NUM_LOCALITIES; busy_locty++) {
+        if (tis->loc[busy_locty].state == TPM_TIS_STATE_EXECUTION) {
+            /*
+             * request the backend to cancel. Some backends may not
+             * support it
+             */
+            tpm_backend_cancel_cmd(s->be_driver);
+            return;
+        }
+    }
+
+    tpm_tis_abort(s, locty);
+}
+
+static void tpm_tis_receive_bh(void *opaque)
+{
+    TPMState *s = opaque;
+    TPMTISEmuState *tis = &s->s.tis;
+    uint8_t locty = s->locty_number;
+
+    tis->loc[locty].sts = TPM_TIS_STS_VALID | TPM_TIS_STS_DATA_AVAILABLE;
+    tis->loc[locty].state = TPM_TIS_STATE_COMPLETION;
+    tis->loc[locty].r_offset = 0;
+    tis->loc[locty].w_offset = 0;
+
+    if (TPM_TIS_IS_VALID_LOCTY(tis->next_locty)) {
+        tpm_tis_abort(s, locty);
+    }
+
+#ifndef RAISE_STS_IRQ
+    tpm_tis_raise_irq(s, locty, TPM_TIS_INT_DATA_AVAILABLE);
+#else
+    tpm_tis_raise_irq(s, locty,
+                      TPM_TIS_INT_DATA_AVAILABLE | TPM_TIS_INT_STS_VALID);
+#endif
+}
+
+/*
+ * Callback from the TPM to indicate that the response was received.
+ */
+static void tpm_tis_receive_cb(TPMState *s, uint8_t locty)
+{
+    TPMTISEmuState *tis = &s->s.tis;
+
+    assert(s->locty_number == locty);
+
+    qemu_bh_schedule(tis->bh);
+}
+
+/*
+ * Read a byte of response data
+ */
+static uint32_t tpm_tis_data_read(TPMState *s, uint8_t locty)
+{
+    TPMTISEmuState *tis = &s->s.tis;
+    uint32_t ret = TPM_TIS_NO_DATA_BYTE;
+    uint16_t len;
+
+    if ((tis->loc[locty].sts & TPM_TIS_STS_DATA_AVAILABLE)) {
+        len = tpm_tis_get_size_from_buffer(&tis->loc[locty].r_buffer);
+
+        ret = tis->loc[locty].r_buffer.buffer[tis->loc[locty].r_offset++];
+        if (tis->loc[locty].r_offset >= len) {
+            /* got last byte */
+            tis->loc[locty].sts = TPM_TIS_STS_VALID;
+#ifdef RAISE_STS_IRQ
+            tpm_tis_raise_irq(s, locty, TPM_TIS_INT_STS_VALID);
+#endif
+        }
+        DPRINTF("tpm_tis: tpm_tis_data_read byte 0x%02x   [%d]\n",
+                ret, tis->loc[locty].r_offset-1);
+    }
+
+    return ret;
+}
+
+#ifdef DEBUG_TIS
+static void tpm_tis_dump_state(void *opaque, hwaddr addr)
+{
+    static const unsigned regs[] = {
+        TPM_TIS_REG_ACCESS,
+        TPM_TIS_REG_INT_ENABLE,
+        TPM_TIS_REG_INT_VECTOR,
+        TPM_TIS_REG_INT_STATUS,
+        TPM_TIS_REG_INTF_CAPABILITY,
+        TPM_TIS_REG_STS,
+        TPM_TIS_REG_DID_VID,
+        TPM_TIS_REG_RID,
+        0xfff};
+    int idx;
+    uint8_t locty = tpm_tis_locality_from_addr(addr);
+    hwaddr base = addr & ~0xfff;
+    TPMState *s = opaque;
+    TPMTISEmuState *tis = &s->s.tis;
+
+    DPRINTF("tpm_tis: active locality      : %d\n"
+            "tpm_tis: state of locality %d : %d\n"
+            "tpm_tis: register dump:\n",
+            tis->active_locty,
+            locty, tis->loc[locty].state);
+
+    for (idx = 0; regs[idx] != 0xfff; idx++) {
+        DPRINTF("tpm_tis: 0x%04x : 0x%08x\n", regs[idx],
+                (uint32_t)tpm_tis_mmio_read(opaque, base + regs[idx], 4));
+    }
+
+    DPRINTF("tpm_tis: read offset   : %d\n"
+            "tpm_tis: result buffer : ",
+            tis->loc[locty].r_offset);
+    for (idx = 0;
+         idx < tpm_tis_get_size_from_buffer(&tis->loc[locty].r_buffer);
+         idx++) {
+        DPRINTF("%c%02x%s",
+                tis->loc[locty].r_offset == idx ? '>' : ' ',
+                tis->loc[locty].r_buffer.buffer[idx],
+                ((idx & 0xf) == 0xf) ? "\ntpm_tis:                 " : "");
+    }
+    DPRINTF("\n"
+            "tpm_tis: write offset  : %d\n"
+            "tpm_tis: request buffer: ",
+            tis->loc[locty].w_offset);
+    for (idx = 0;
+         idx < tpm_tis_get_size_from_buffer(&tis->loc[locty].w_buffer);
+         idx++) {
+        DPRINTF("%c%02x%s",
+                tis->loc[locty].w_offset == idx ? '>' : ' ',
+                tis->loc[locty].w_buffer.buffer[idx],
+                ((idx & 0xf) == 0xf) ? "\ntpm_tis:                 " : "");
+    }
+    DPRINTF("\n");
+}
+#endif
+
+/*
+ * Read a register of the TIS interface
+ * See specs pages 33-63 for description of the registers
+ */
+static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr addr,
+                                  unsigned size)
+{
+    TPMState *s = opaque;
+    TPMTISEmuState *tis = &s->s.tis;
+    uint16_t offset = addr & 0xffc;
+    uint8_t shift = (addr & 0x3) * 8;
+    uint32_t val = 0xffffffff;
+    uint8_t locty = tpm_tis_locality_from_addr(addr);
+    uint32_t avail;
+
+    if (tpm_backend_had_startup_error(s->be_driver)) {
+        return val;
+    }
+
+    switch (offset) {
+    case TPM_TIS_REG_ACCESS:
+        /* never show the SEIZE flag even though we use it internally */
+        val = tis->loc[locty].access & ~TPM_TIS_ACCESS_SEIZE;
+        /* the pending flag is always calculated */
+        if (tpm_tis_check_request_use_except(s, locty)) {
+            val |= TPM_TIS_ACCESS_PENDING_REQUEST;
+        }
+        val |= !tpm_backend_get_tpm_established_flag(s->be_driver);
+        break;
+    case TPM_TIS_REG_INT_ENABLE:
+        val = tis->loc[locty].inte;
+        break;
+    case TPM_TIS_REG_INT_VECTOR:
+        val = tis->irq_num;
+        break;
+    case TPM_TIS_REG_INT_STATUS:
+        val = tis->loc[locty].ints;
+        break;
+    case TPM_TIS_REG_INTF_CAPABILITY:
+        val = TPM_TIS_CAPABILITIES_SUPPORTED;
+        break;
+    case TPM_TIS_REG_STS:
+        if (tis->active_locty == locty) {
+            if ((tis->loc[locty].sts & TPM_TIS_STS_DATA_AVAILABLE)) {
+                val = TPM_TIS_BURST_COUNT(
+                       tpm_tis_get_size_from_buffer(&tis->loc[locty].r_buffer)
+                       - tis->loc[locty].r_offset) | tis->loc[locty].sts;
+            } else {
+                avail = tis->loc[locty].w_buffer.size
+                        - tis->loc[locty].w_offset;
+                /*
+                 * byte-sized reads should not return 0x00 for 0x100
+                 * available bytes.
+                 */
+                if (size == 1 && avail > 0xff) {
+                    avail = 0xff;
+                }
+                val = TPM_TIS_BURST_COUNT(avail) | tis->loc[locty].sts;
+            }
+        }
+        break;
+    case TPM_TIS_REG_DATA_FIFO:
+        if (tis->active_locty == locty) {
+            switch (tis->loc[locty].state) {
+            case TPM_TIS_STATE_COMPLETION:
+                val = tpm_tis_data_read(s, locty);
+                break;
+            default:
+                val = TPM_TIS_NO_DATA_BYTE;
+                break;
+            }
+        }
+        break;
+    case TPM_TIS_REG_DID_VID:
+        val = (TPM_TIS_TPM_DID << 16) | TPM_TIS_TPM_VID;
+        break;
+    case TPM_TIS_REG_RID:
+        val = TPM_TIS_TPM_RID;
+        break;
+#ifdef DEBUG_TIS
+    case TPM_TIS_REG_DEBUG:
+        tpm_tis_dump_state(opaque, addr);
+        break;
+#endif
+    }
+
+    if (shift) {
+        val >>= shift;
+    }
+
+    DPRINTF("tpm_tis:  read.%u(%08x) = %08x\n", size, (int)addr, (uint32_t)val);
+
+    return val;
+}
+
+/*
+ * Write a value to a register of the TIS interface
+ * See specs pages 33-63 for description of the registers
+ */
+static void tpm_tis_mmio_write_intern(void *opaque, hwaddr addr,
+                                      uint64_t val, unsigned size,
+                                      bool hw_access)
+{
+    TPMState *s = opaque;
+    TPMTISEmuState *tis = &s->s.tis;
+    uint16_t off = addr & 0xfff;
+    uint8_t locty = tpm_tis_locality_from_addr(addr);
+    uint8_t active_locty, l;
+    int c, set_new_locty = 1;
+    uint16_t len;
+
+    DPRINTF("tpm_tis: write.%u(%08x) = %08x\n", size, (int)addr, (uint32_t)val);
+
+    if (locty == 4 && !hw_access) {
+        DPRINTF("tpm_tis: Access to locality 4 only allowed from hardware\n");
+        return;
+    }
+
+    if (tpm_backend_had_startup_error(s->be_driver)) {
+        return;
+    }
+
+    switch (off) {
+    case TPM_TIS_REG_ACCESS:
+
+        if ((val & TPM_TIS_ACCESS_SEIZE)) {
+            val &= ~(TPM_TIS_ACCESS_REQUEST_USE |
+                     TPM_TIS_ACCESS_ACTIVE_LOCALITY);
+        }
+
+        active_locty = tis->active_locty;
+
+        if ((val & TPM_TIS_ACCESS_ACTIVE_LOCALITY)) {
+            /* give up locality if currently owned */
+            if (tis->active_locty == locty) {
+                DPRINTF("tpm_tis: Releasing locality %d\n", locty);
+
+                uint8_t newlocty = TPM_TIS_NO_LOCALITY;
+                /* anybody wants the locality ? */
+                for (c = TPM_TIS_NUM_LOCALITIES - 1; c >= 0; c--) {
+                    if ((tis->loc[c].access & TPM_TIS_ACCESS_REQUEST_USE)) {
+                        DPRINTF("tpm_tis: Locality %d requests use.\n", c);
+                        newlocty = c;
+                        break;
+                    }
+                }
+                DPRINTF("tpm_tis: TPM_TIS_ACCESS_ACTIVE_LOCALITY: "
+                        "Next active locality: %d\n",
+                        newlocty);
+
+                if (TPM_TIS_IS_VALID_LOCTY(newlocty)) {
+                    set_new_locty = 0;
+                    tpm_tis_prep_abort(s, locty, newlocty);
+                } else {
+                    active_locty = TPM_TIS_NO_LOCALITY;
+                }
+            } else {
+                /* not currently the owner; clear a pending request */
+                tis->loc[locty].access &= ~TPM_TIS_ACCESS_REQUEST_USE;
+            }
+        }
+
+        if ((val & TPM_TIS_ACCESS_BEEN_SEIZED)) {
+            tis->loc[locty].access &= ~TPM_TIS_ACCESS_BEEN_SEIZED;
+        }
+
+        if ((val & TPM_TIS_ACCESS_SEIZE)) {
+            /*
+             * allow seize if a locality is active and the requesting
+             * locality is higher than the one that's active
+             * OR
+             * allow seize for requesting locality if no locality is
+             * active
+             */
+            while ((TPM_TIS_IS_VALID_LOCTY(tis->active_locty) &&
+                    locty > tis->active_locty) ||
+                    !TPM_TIS_IS_VALID_LOCTY(tis->active_locty)) {
+                bool higher_seize = FALSE;
+
+                /* already a pending SEIZE ? */
+                if ((tis->loc[locty].access & TPM_TIS_ACCESS_SEIZE)) {
+                    break;
+                }
+
+                /* check for ongoing seize by a higher locality */
+                for (l = locty + 1; l < TPM_TIS_NUM_LOCALITIES; l++) {
+                    if ((tis->loc[l].access & TPM_TIS_ACCESS_SEIZE)) {
+                        higher_seize = TRUE;
+                        break;
+                    }
+                }
+
+                if (higher_seize) {
+                    break;
+                }
+
+                /* cancel any seize by a lower locality */
+                for (l = 0; l < locty - 1; l++) {
+                    tis->loc[l].access &= ~TPM_TIS_ACCESS_SEIZE;
+                }
+
+                tis->loc[locty].access |= TPM_TIS_ACCESS_SEIZE;
+                DPRINTF("tpm_tis: TPM_TIS_ACCESS_SEIZE: "
+                        "Locality %d seized from locality %d\n",
+                        locty, tis->active_locty);
+                DPRINTF("tpm_tis: TPM_TIS_ACCESS_SEIZE: Initiating abort.\n");
+                set_new_locty = 0;
+                tpm_tis_prep_abort(s, tis->active_locty, locty);
+                break;
+            }
+        }
+
+        if ((val & TPM_TIS_ACCESS_REQUEST_USE)) {
+            if (tis->active_locty != locty) {
+                if (TPM_TIS_IS_VALID_LOCTY(tis->active_locty)) {
+                    tis->loc[locty].access |= TPM_TIS_ACCESS_REQUEST_USE;
+                } else {
+                    /* no locality active -> make this one active now */
+                    active_locty = locty;
+                }
+            }
+        }
+
+        if (set_new_locty) {
+            tpm_tis_new_active_locality(s, active_locty);
+        }
+
+        break;
+    case TPM_TIS_REG_INT_ENABLE:
+        if (tis->active_locty != locty) {
+            break;
+        }
+
+        tis->loc[locty].inte = (val & (TPM_TIS_INT_ENABLED |
+                                       TPM_TIS_INT_POLARITY_MASK |
+                                       TPM_TIS_INTERRUPTS_SUPPORTED));
+        break;
+    case TPM_TIS_REG_INT_VECTOR:
+        /* hard wired -- ignore */
+        break;
+    case TPM_TIS_REG_INT_STATUS:
+        if (tis->active_locty != locty) {
+            break;
+        }
+
+        /* clearing of interrupt flags */
+        if (((val & TPM_TIS_INTERRUPTS_SUPPORTED)) &&
+            (tis->loc[locty].ints & TPM_TIS_INTERRUPTS_SUPPORTED)) {
+            tis->loc[locty].ints &= ~val;
+            if (tis->loc[locty].ints == 0) {
+                qemu_irq_lower(tis->irq);
+                DPRINTF("tpm_tis: Lowering IRQ\n");
+            }
+        }
+        tis->loc[locty].ints &= ~(val & TPM_TIS_INTERRUPTS_SUPPORTED);
+        break;
+    case TPM_TIS_REG_STS:
+        if (tis->active_locty != locty) {
+            break;
+        }
+
+        val &= (TPM_TIS_STS_COMMAND_READY | TPM_TIS_STS_TPM_GO |
+                TPM_TIS_STS_RESPONSE_RETRY);
+
+        if (val == TPM_TIS_STS_COMMAND_READY) {
+            switch (tis->loc[locty].state) {
+
+            case TPM_TIS_STATE_READY:
+                tis->loc[locty].w_offset = 0;
+                tis->loc[locty].r_offset = 0;
+            break;
+
+            case TPM_TIS_STATE_IDLE:
+                tis->loc[locty].sts = TPM_TIS_STS_COMMAND_READY;
+                tis->loc[locty].state = TPM_TIS_STATE_READY;
+                tpm_tis_raise_irq(s, locty, TPM_TIS_INT_COMMAND_READY);
+            break;
+
+            case TPM_TIS_STATE_EXECUTION:
+            case TPM_TIS_STATE_RECEPTION:
+                /* abort currently running command */
+                DPRINTF("tpm_tis: %s: Initiating abort.\n",
+                        __func__);
+                tpm_tis_prep_abort(s, locty, locty);
+            break;
+
+            case TPM_TIS_STATE_COMPLETION:
+                tis->loc[locty].w_offset = 0;
+                tis->loc[locty].r_offset = 0;
+                /* shortcut to ready state with C/R set */
+                tis->loc[locty].state = TPM_TIS_STATE_READY;
+                if (!(tis->loc[locty].sts & TPM_TIS_STS_COMMAND_READY)) {
+                    tis->loc[locty].sts   = TPM_TIS_STS_COMMAND_READY;
+                    tpm_tis_raise_irq(s, locty, TPM_TIS_INT_COMMAND_READY);
+                }
+                tis->loc[locty].sts &= ~(TPM_TIS_STS_DATA_AVAILABLE);
+            break;
+
+            }
+        } else if (val == TPM_TIS_STS_TPM_GO) {
+            switch (tis->loc[locty].state) {
+            case TPM_TIS_STATE_RECEPTION:
+                if ((tis->loc[locty].sts & TPM_TIS_STS_EXPECT) == 0) {
+                    tpm_tis_tpm_send(s, locty);
+                }
+                break;
+            default:
+                /* ignore */
+                break;
+            }
+        } else if (val == TPM_TIS_STS_RESPONSE_RETRY) {
+            switch (tis->loc[locty].state) {
+            case TPM_TIS_STATE_COMPLETION:
+                tis->loc[locty].r_offset = 0;
+                tis->loc[locty].sts = TPM_TIS_STS_VALID |
+                                      TPM_TIS_STS_DATA_AVAILABLE;
+                break;
+            default:
+                /* ignore */
+                break;
+            }
+        }
+        break;
+    case TPM_TIS_REG_DATA_FIFO:
+        /* data fifo */
+        if (tis->active_locty != locty) {
+            break;
+        }
+
+        if (tis->loc[locty].state == TPM_TIS_STATE_IDLE ||
+            tis->loc[locty].state == TPM_TIS_STATE_EXECUTION ||
+            tis->loc[locty].state == TPM_TIS_STATE_COMPLETION) {
+            /* drop the byte */
+        } else {
+            DPRINTF("tpm_tis: Byte to send to TPM: %02x\n", (uint8_t)val);
+            if (tis->loc[locty].state == TPM_TIS_STATE_READY) {
+                tis->loc[locty].state = TPM_TIS_STATE_RECEPTION;
+                tis->loc[locty].sts = TPM_TIS_STS_EXPECT | TPM_TIS_STS_VALID;
+            }
+
+            if ((tis->loc[locty].sts & TPM_TIS_STS_EXPECT)) {
+                if (tis->loc[locty].w_offset < tis->loc[locty].w_buffer.size) {
+                    tis->loc[locty].w_buffer.
+                        buffer[tis->loc[locty].w_offset++] = (uint8_t)val;
+                } else {
+                    tis->loc[locty].sts = TPM_TIS_STS_VALID;
+                }
+            }
+
+            /* check for complete packet */
+            if (tis->loc[locty].w_offset > 5 &&
+                (tis->loc[locty].sts & TPM_TIS_STS_EXPECT)) {
+                /* we have a packet length - see if we have all of it */
+#ifdef RAISE_STS_IRQ
+                bool needIrq = !(tis->loc[locty].sts & TPM_TIS_STS_VALID);
+#endif
+                len = tpm_tis_get_size_from_buffer(&tis->loc[locty].w_buffer);
+                if (len > tis->loc[locty].w_offset) {
+                    tis->loc[locty].sts = TPM_TIS_STS_EXPECT |
+                                          TPM_TIS_STS_VALID;
+                } else {
+                    /* packet complete */
+                    tis->loc[locty].sts = TPM_TIS_STS_VALID;
+                }
+#ifdef RAISE_STS_IRQ
+                if (needIrq) {
+                    tpm_tis_raise_irq(s, locty, TPM_TIS_INT_STS_VALID);
+                }
+#endif
+            }
+        }
+        break;
+    }
+}
+
+static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
+                               uint64_t val, unsigned size)
+{
+    return tpm_tis_mmio_write_intern(opaque, addr, val, size, false);
+}
+
+static const MemoryRegionOps tpm_tis_memory_ops = {
+    .read = tpm_tis_mmio_read,
+    .write = tpm_tis_mmio_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid = {
+        .min_access_size = 1,
+        .max_access_size = 4,
+    },
+};
+
+static int tpm_tis_do_startup_tpm(TPMState *s)
+{
+    return tpm_backend_startup_tpm(s->be_driver);
+}
+
+/*
+ * This function is called when the machine starts, resets or due to
+ * S3 resume.
+ */
+static void tpm_tis_reset(DeviceState *dev)
+{
+    TPMState *s = TPM(dev);
+    TPMTISEmuState *tis = &s->s.tis;
+    int c;
+
+    tpm_backend_reset(s->be_driver);
+
+    tis->active_locty = TPM_TIS_NO_LOCALITY;
+    tis->next_locty = TPM_TIS_NO_LOCALITY;
+    tis->aborting_locty = TPM_TIS_NO_LOCALITY;
+
+    for (c = 0; c < TPM_TIS_NUM_LOCALITIES; c++) {
+        tis->loc[c].access = TPM_TIS_ACCESS_TPM_REG_VALID_STS;
+        tis->loc[c].sts = 0;
+        tis->loc[c].inte = TPM_TIS_INT_POLARITY_LOW_LEVEL;
+        tis->loc[c].ints = 0;
+        tis->loc[c].state = TPM_TIS_STATE_IDLE;
+
+        tis->loc[c].w_offset = 0;
+        tpm_backend_realloc_buffer(s->be_driver, &tis->loc[c].w_buffer);
+        tis->loc[c].r_offset = 0;
+        tpm_backend_realloc_buffer(s->be_driver, &tis->loc[c].r_buffer);
+    }
+
+    tpm_tis_do_startup_tpm(s);
+}
+
+static const VMStateDescription vmstate_tpm_tis = {
+    .name = "tpm",
+    .unmigratable = 1,
+};
+
+static Property tpm_tis_properties[] = {
+    DEFINE_PROP_UINT32("irq", TPMState,
+                       s.tis.irq_num, TPM_TIS_IRQ),
+    DEFINE_PROP_STRING("tpmdev", TPMState, backend),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void tpm_tis_realizefn(DeviceState *dev, Error **errp)
+{
+    TPMState *s = TPM(dev);
+    TPMTISEmuState *tis = &s->s.tis;
+
+    s->be_driver = qemu_find_tpm(s->backend);
+    if (!s->be_driver) {
+        error_setg(errp, "tpm_tis: backend driver with id %s could not be "
+                   "found", s->backend);
+        return;
+    }
+
+    s->be_driver->fe_model = TPM_MODEL_TPM_TIS;
+
+    if (tpm_backend_init(s->be_driver, s, tpm_tis_receive_cb)) {
+        error_setg(errp, "tpm_tis: backend driver with id %s could not be "
+                   "initialized", s->backend);
+        return;
+    }
+
+    if (tis->irq_num > 15) {
+        error_setg(errp, "tpm_tis: IRQ %d for TPM TIS is outside valid range "
+                   "of 0 to 15.\n", tis->irq_num);
+        return;
+    }
+
+    tis->bh = qemu_bh_new(tpm_tis_receive_bh, s);
+
+    isa_init_irq(&s->busdev, &tis->irq, tis->irq_num);
+}
+
+static void tpm_tis_initfn(Object *obj)
+{
+    ISADevice *dev = ISA_DEVICE(obj);
+    TPMState *s = TPM(obj);
+
+    memory_region_init_io(&s->mmio, &tpm_tis_memory_ops, s, "tpm-tis-mmio",
+                          TPM_TIS_NUM_LOCALITIES << TPM_TIS_LOCALITY_SHIFT);
+    memory_region_add_subregion(isa_address_space(dev), TPM_TIS_ADDR_BASE,
+                                &s->mmio);
+}
+
+static void tpm_tis_uninitfn(Object *obj)
+{
+    TPMState *s = TPM(obj);
+
+    memory_region_del_subregion(get_system_memory(), &s->mmio);
+    memory_region_destroy(&s->mmio);
+}
+
+static void tpm_tis_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = tpm_tis_realizefn;
+    dc->props = tpm_tis_properties;
+    dc->reset = tpm_tis_reset;
+    dc->vmsd  = &vmstate_tpm_tis;
+}
+
+static const TypeInfo tpm_tis_info = {
+    .name = TYPE_TPM_TIS,
+    .parent = TYPE_ISA_DEVICE,
+    .instance_size = sizeof(TPMState),
+    .instance_init = tpm_tis_initfn,
+    .instance_finalize = tpm_tis_uninitfn,
+    .class_init  = tpm_tis_class_init,
+};
+
+static void tpm_tis_register(void)
+{
+    type_register_static(&tpm_tis_info);
+    tpm_register_model(TPM_MODEL_TPM_TIS);
+}
+
+type_init(tpm_tis_register)
diff --git a/hw/tpm/tpm_tis.h b/hw/tpm/tpm_tis.h
new file mode 100644
index 0000000..916152a
--- /dev/null
+++ b/hw/tpm/tpm_tis.h
@@ -0,0 +1,75 @@
+/*
+ * tpm_tis.h - QEMU's TPM TIS interface emulator
+ *
+ * Copyright (C) 2006, 2010-2013 IBM Corporation
+ *
+ * Authors:
+ *  Stefan Berger <stefanb@us.ibm.com>
+ *  David Safford <safford@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ * Implementation of the TIS interface according to specs found at
+ * http://www.trustedcomputinggroup.org
+ *
+ */
+#ifndef TPM_TPM_TIS_H
+#define TPM_TPM_TIS_H
+
+#include "hw/isa/isa.h"
+#include "qemu-common.h"
+
+#define TPM_TIS_ADDR_BASE           0xFED40000
+
+#define TPM_TIS_NUM_LOCALITIES      5     /* per spec */
+#define TPM_TIS_LOCALITY_SHIFT      12
+#define TPM_TIS_NO_LOCALITY         0xff
+
+#define TPM_TIS_IS_VALID_LOCTY(x)   ((x) < TPM_TIS_NUM_LOCALITIES)
+
+#define TPM_TIS_IRQ                 5
+
+#define TPM_TIS_BUFFER_MAX          4096
+
+#define TYPE_TPM_TIS                "tpm-tis"
+
+
+typedef enum {
+    TPM_TIS_STATE_IDLE = 0,
+    TPM_TIS_STATE_READY,
+    TPM_TIS_STATE_COMPLETION,
+    TPM_TIS_STATE_EXECUTION,
+    TPM_TIS_STATE_RECEPTION,
+} TPMTISState;
+
+/* locality data  -- all fields are persisted */
+typedef struct TPMLocality {
+    TPMTISState state;
+    uint8_t access;
+    uint8_t sts;
+    uint32_t inte;
+    uint32_t ints;
+
+    uint16_t w_offset;
+    uint16_t r_offset;
+    TPMSizedBuffer w_buffer;
+    TPMSizedBuffer r_buffer;
+} TPMLocality;
+
+typedef struct TPMTISEmuState {
+    QEMUBH *bh;
+    uint32_t offset;
+    uint8_t buf[TPM_TIS_BUFFER_MAX];
+
+    uint8_t active_locty;
+    uint8_t aborting_locty;
+    uint8_t next_locty;
+
+    TPMLocality loc[TPM_TIS_NUM_LOCALITIES];
+
+    qemu_irq irq;
+    uint32_t irq_num;
+} TPMTISEmuState;
+
+#endif /* TPM_TPM_TIS_H */