xref: /openbmc/qemu/tests/qtest/tpm-tis-util.c (revision 8acf8650)
1 /*
2  * QTest testcase for TPM TIS: common test functions used for both
3  * the ISA and SYSBUS devices
4  *
5  * Copyright (c) 2018 Red Hat, Inc.
6  * Copyright (c) 2018 IBM Corporation
7  *
8  * Authors:
9  *   Marc-André Lureau <marcandre.lureau@redhat.com>
10  *   Stefan Berger <stefanb@linux.vnet.ibm.com>
11  *
12  * This work is licensed under the terms of the GNU GPL, version 2 or later.
13  * See the COPYING file in the top-level directory.
14  */
15 
16 #include "qemu/osdep.h"
17 #include <glib/gstdio.h>
18 
19 #include "hw/acpi/tpm.h"
20 #include "io/channel-socket.h"
21 #include "libqtest-single.h"
22 #include "qemu/module.h"
23 #include "tpm-emu.h"
24 #include "tpm-util.h"
25 #include "tpm-tis-util.h"
26 
27 #define DEBUG_TIS_TEST 0
28 
29 #define DPRINTF(fmt, ...) do { \
30     if (DEBUG_TIS_TEST) { \
31         printf(fmt, ## __VA_ARGS__); \
32     } \
33 } while (0)
34 
35 #define DPRINTF_ACCESS \
36     DPRINTF("%s: %d: locty=%d l=%d access=0x%02x pending_request_flag=0x%x\n", \
37             __func__, __LINE__, locty, l, access, pending_request_flag)
38 
39 #define DPRINTF_STS \
40     DPRINTF("%s: %d: sts = 0x%08x\n", __func__, __LINE__, sts)
41 
42 static const uint8_t TPM_CMD[12] =
43     "\x80\x01\x00\x00\x00\x0c\x00\x00\x01\x44\x00\x00";
44 
45 void tpm_tis_test_check_localities(const void *data)
46 {
47     uint8_t locty;
48     uint8_t access;
49     uint32_t ifaceid;
50     uint32_t capability;
51     uint32_t didvid;
52     uint32_t rid;
53 
54     for (locty = 0; locty < TPM_TIS_NUM_LOCALITIES; locty++) {
55         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
56         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
57                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
58 
59         capability = readl(TIS_REG(locty, TPM_TIS_REG_INTF_CAPABILITY));
60         g_assert_cmpint(capability, ==, TPM_TIS_CAPABILITIES_SUPPORTED2_0);
61 
62         ifaceid = readl(TIS_REG(locty, TPM_TIS_REG_INTERFACE_ID));
63         g_assert_cmpint(ifaceid, ==, TPM_TIS_IFACE_ID_SUPPORTED_FLAGS2_0);
64 
65         didvid = readl(TIS_REG(locty, TPM_TIS_REG_DID_VID));
66         g_assert_cmpint(didvid, !=, 0);
67         g_assert_cmpint(didvid, !=, 0xffffffff);
68 
69         rid = readl(TIS_REG(locty, TPM_TIS_REG_RID));
70         g_assert_cmpint(rid, !=, 0);
71         g_assert_cmpint(rid, !=, 0xffffffff);
72     }
73 }
74 
75 void tpm_tis_test_check_access_reg(const void *data)
76 {
77     uint8_t locty;
78     uint8_t access;
79 
80     /* do not test locality 4 (hw only) */
81     for (locty = 0; locty < TPM_TIS_NUM_LOCALITIES - 1; locty++) {
82         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
83         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
84                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
85 
86         /* request use of locality */
87         writeb(TIS_REG(locty, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
88 
89         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
90         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
91                                     TPM_TIS_ACCESS_ACTIVE_LOCALITY |
92                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
93 
94         /* release access */
95         writeb(TIS_REG(locty, TPM_TIS_REG_ACCESS),
96                TPM_TIS_ACCESS_ACTIVE_LOCALITY);
97         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
98         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
99                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
100     }
101 }
102 
103 /*
104  * Test case for seizing access by a higher number locality
105  */
106 void tpm_tis_test_check_access_reg_seize(const void *data)
107 {
108     int locty, l;
109     uint8_t access;
110     uint8_t pending_request_flag;
111 
112     /* do not test locality 4 (hw only) */
113     for (locty = 0; locty < TPM_TIS_NUM_LOCALITIES - 1; locty++) {
114         pending_request_flag = 0;
115 
116         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
117         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
118                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
119 
120         /* request use of locality */
121         writeb(TIS_REG(locty, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
122         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
123         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
124                                     TPM_TIS_ACCESS_ACTIVE_LOCALITY |
125                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
126 
127         /* lower localities cannot seize access */
128         for (l = 0; l < locty; l++) {
129             /* lower locality is not active */
130             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
131             DPRINTF_ACCESS;
132             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
133                                         pending_request_flag |
134                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
135 
136             /* try to request use from 'l' */
137             writeb(TIS_REG(l, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
138 
139             /*
140              * requesting use from 'l' was not possible;
141              * we must see REQUEST_USE and possibly PENDING_REQUEST
142              */
143             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
144             DPRINTF_ACCESS;
145             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
146                                         TPM_TIS_ACCESS_REQUEST_USE |
147                                         pending_request_flag |
148                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
149 
150             /*
151              * locality 'locty' must be unchanged;
152              * we must see PENDING_REQUEST
153              */
154             access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
155             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
156                                         TPM_TIS_ACCESS_ACTIVE_LOCALITY |
157                                         TPM_TIS_ACCESS_PENDING_REQUEST |
158                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
159 
160             /* try to seize from 'l' */
161             writeb(TIS_REG(l, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_SEIZE);
162             /* seize from 'l' was not possible */
163             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
164             DPRINTF_ACCESS;
165             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
166                                         TPM_TIS_ACCESS_REQUEST_USE |
167                                         pending_request_flag |
168                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
169 
170             /* locality 'locty' must be unchanged */
171             access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
172             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
173                                         TPM_TIS_ACCESS_ACTIVE_LOCALITY |
174                                         TPM_TIS_ACCESS_PENDING_REQUEST |
175                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
176 
177             /*
178              * on the next loop we will have a PENDING_REQUEST flag
179              * set for locality 'l'
180              */
181             pending_request_flag = TPM_TIS_ACCESS_PENDING_REQUEST;
182         }
183 
184         /*
185          * higher localities can 'seize' access but not 'request use';
186          * note: this will activate first l+1, then l+2 etc.
187          */
188         for (l = locty + 1; l < TPM_TIS_NUM_LOCALITIES - 1; l++) {
189             /* try to 'request use' from 'l' */
190             writeb(TIS_REG(l, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
191 
192             /*
193              * requesting use from 'l' was not possible; we should see
194              * REQUEST_USE and may see PENDING_REQUEST
195              */
196             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
197             DPRINTF_ACCESS;
198             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
199                                         TPM_TIS_ACCESS_REQUEST_USE |
200                                         pending_request_flag |
201                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
202 
203             /*
204              * locality 'l-1' must be unchanged; we should always
205              * see PENDING_REQUEST from 'l' requesting access
206              */
207             access = readb(TIS_REG(l - 1, TPM_TIS_REG_ACCESS));
208             DPRINTF_ACCESS;
209             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
210                                         TPM_TIS_ACCESS_ACTIVE_LOCALITY |
211                                         TPM_TIS_ACCESS_PENDING_REQUEST |
212                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
213 
214             /* try to seize from 'l' */
215             writeb(TIS_REG(l, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_SEIZE);
216 
217             /* seize from 'l' was possible */
218             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
219             DPRINTF_ACCESS;
220             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
221                                         TPM_TIS_ACCESS_ACTIVE_LOCALITY |
222                                         pending_request_flag |
223                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
224 
225             /* l - 1 should show that it has BEEN_SEIZED */
226             access = readb(TIS_REG(l - 1, TPM_TIS_REG_ACCESS));
227             DPRINTF_ACCESS;
228             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
229                                         TPM_TIS_ACCESS_BEEN_SEIZED |
230                                         pending_request_flag |
231                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
232 
233             /* clear the BEEN_SEIZED flag and make sure it's gone */
234             writeb(TIS_REG(l - 1, TPM_TIS_REG_ACCESS),
235                    TPM_TIS_ACCESS_BEEN_SEIZED);
236 
237             access = readb(TIS_REG(l - 1, TPM_TIS_REG_ACCESS));
238             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
239                                         pending_request_flag |
240                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
241         }
242 
243         /*
244          * PENDING_REQUEST will not be set if locty = 0 since all localities
245          * were active; in case of locty = 1, locality 0 will be active
246          * but no PENDING_REQUEST anywhere
247          */
248         if (locty <= 1) {
249             pending_request_flag = 0;
250         }
251 
252         /* release access from l - 1; this activates locty - 1 */
253         l--;
254 
255         access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
256         DPRINTF_ACCESS;
257 
258         DPRINTF("%s: %d: relinquishing control on l = %d\n",
259                 __func__, __LINE__, l);
260         writeb(TIS_REG(l, TPM_TIS_REG_ACCESS),
261                TPM_TIS_ACCESS_ACTIVE_LOCALITY);
262 
263         access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
264         DPRINTF_ACCESS;
265         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
266                                     pending_request_flag |
267                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
268 
269         for (l = locty - 1; l >= 0; l--) {
270             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
271             DPRINTF_ACCESS;
272             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
273                                         TPM_TIS_ACCESS_ACTIVE_LOCALITY |
274                                         pending_request_flag |
275                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
276 
277             /* release this locality */
278             writeb(TIS_REG(l, TPM_TIS_REG_ACCESS),
279                    TPM_TIS_ACCESS_ACTIVE_LOCALITY);
280 
281             if (l == 1) {
282                 pending_request_flag = 0;
283             }
284         }
285 
286         /* no locality may be active now */
287         for (l = 0; l < TPM_TIS_NUM_LOCALITIES - 1; l++) {
288             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
289             DPRINTF_ACCESS;
290             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
291                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
292         }
293     }
294 }
295 
296 /*
297  * Test case for getting access when higher number locality relinquishes access
298  */
299 void tpm_tis_test_check_access_reg_release(const void *data)
300 {
301     int locty, l;
302     uint8_t access;
303     uint8_t pending_request_flag;
304 
305     /* do not test locality 4 (hw only) */
306     for (locty = TPM_TIS_NUM_LOCALITIES - 2; locty >= 0; locty--) {
307         pending_request_flag = 0;
308 
309         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
310         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
311                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
312 
313         /* request use of locality */
314         writeb(TIS_REG(locty, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
315         access = readb(TIS_REG(locty, TPM_TIS_REG_ACCESS));
316         g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
317                                     TPM_TIS_ACCESS_ACTIVE_LOCALITY |
318                                     TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
319 
320         /* request use of all other localities */
321         for (l = 0; l < TPM_TIS_NUM_LOCALITIES - 1; l++) {
322             if (l == locty) {
323                 continue;
324             }
325             /*
326              * request use of locality 'l' -- we MUST see REQUEST USE and
327              * may see PENDING_REQUEST
328              */
329             writeb(TIS_REG(l, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
330             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
331             DPRINTF_ACCESS;
332             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
333                                         TPM_TIS_ACCESS_REQUEST_USE |
334                                         pending_request_flag |
335                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
336             pending_request_flag = TPM_TIS_ACCESS_PENDING_REQUEST;
337         }
338         /* release locality 'locty' */
339         writeb(TIS_REG(locty, TPM_TIS_REG_ACCESS),
340                TPM_TIS_ACCESS_ACTIVE_LOCALITY);
341         /*
342          * highest locality should now be active; release it and make sure the
343          * next higest locality is active afterwards
344          */
345         for (l = TPM_TIS_NUM_LOCALITIES - 2; l >= 0; l--) {
346             if (l == locty) {
347                 continue;
348             }
349             /* 'l' should be active now */
350             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
351             DPRINTF_ACCESS;
352             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
353                                         TPM_TIS_ACCESS_ACTIVE_LOCALITY |
354                                         pending_request_flag |
355                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
356             /* 'l' relinquishes access */
357             writeb(TIS_REG(l, TPM_TIS_REG_ACCESS),
358                    TPM_TIS_ACCESS_ACTIVE_LOCALITY);
359             access = readb(TIS_REG(l, TPM_TIS_REG_ACCESS));
360             DPRINTF_ACCESS;
361             if (l == 1 || (locty <= 1 && l == 2)) {
362                 pending_request_flag = 0;
363             }
364             g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
365                                         pending_request_flag |
366                                         TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
367         }
368     }
369 }
370 
371 /*
372  * Test case for transmitting packets
373  */
374 void tpm_tis_test_check_transmit(const void *data)
375 {
376     const TPMTestState *s = data;
377     uint8_t access;
378     uint32_t sts;
379     uint16_t bcount;
380     size_t i;
381 
382     /* request use of locality 0 */
383     writeb(TIS_REG(0, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
384     access = readb(TIS_REG(0, TPM_TIS_REG_ACCESS));
385     g_assert_cmpint(access, ==, TPM_TIS_ACCESS_TPM_REG_VALID_STS |
386                                 TPM_TIS_ACCESS_ACTIVE_LOCALITY |
387                                 TPM_TIS_ACCESS_TPM_ESTABLISHMENT);
388 
389     sts = readl(TIS_REG(0, TPM_TIS_REG_STS));
390     DPRINTF_STS;
391 
392     g_assert_cmpint(sts & 0xff, ==, 0);
393     g_assert_cmpint(sts & TPM_TIS_STS_TPM_FAMILY_MASK, ==,
394                     TPM_TIS_STS_TPM_FAMILY2_0);
395 
396     bcount = (sts >> 8) & 0xffff;
397     g_assert_cmpint(bcount, >=, 128);
398 
399     writel(TIS_REG(0, TPM_TIS_REG_STS), TPM_TIS_STS_COMMAND_READY);
400     sts = readl(TIS_REG(0, TPM_TIS_REG_STS));
401     DPRINTF_STS;
402     g_assert_cmpint(sts & 0xff, ==, TPM_TIS_STS_COMMAND_READY);
403 
404     /* transmit command */
405     for (i = 0; i < sizeof(TPM_CMD); i++) {
406         writeb(TIS_REG(0, TPM_TIS_REG_DATA_FIFO), TPM_CMD[i]);
407         sts = readl(TIS_REG(0, TPM_TIS_REG_STS));
408         DPRINTF_STS;
409         if (i < sizeof(TPM_CMD) - 1) {
410             g_assert_cmpint(sts & 0xff, ==,
411                             TPM_TIS_STS_EXPECT | TPM_TIS_STS_VALID);
412         } else {
413             g_assert_cmpint(sts & 0xff, ==, TPM_TIS_STS_VALID);
414         }
415         g_assert_cmpint((sts >> 8) & 0xffff, ==, --bcount);
416     }
417     /* start processing */
418     writeb(TIS_REG(0, TPM_TIS_REG_STS), TPM_TIS_STS_TPM_GO);
419 
420     uint64_t end_time = g_get_monotonic_time() + 50 * G_TIME_SPAN_SECOND;
421     do {
422         sts = readl(TIS_REG(0, TPM_TIS_REG_STS));
423         if ((sts & TPM_TIS_STS_DATA_AVAILABLE) != 0) {
424             break;
425         }
426     } while (g_get_monotonic_time() < end_time);
427 
428     sts = readl(TIS_REG(0, TPM_TIS_REG_STS));
429     DPRINTF_STS;
430     g_assert_cmpint(sts & 0xff, == ,
431                     TPM_TIS_STS_VALID | TPM_TIS_STS_DATA_AVAILABLE);
432     bcount = (sts >> 8) & 0xffff;
433 
434     /* read response */
435     uint8_t tpm_msg[sizeof(struct tpm_hdr)];
436     g_assert_cmpint(sizeof(tpm_msg), ==, bcount);
437 
438     for (i = 0; i < sizeof(tpm_msg); i++) {
439         tpm_msg[i] = readb(TIS_REG(0, TPM_TIS_REG_DATA_FIFO));
440         sts = readl(TIS_REG(0, TPM_TIS_REG_STS));
441         DPRINTF_STS;
442         if (sts & TPM_TIS_STS_DATA_AVAILABLE) {
443             g_assert_cmpint((sts >> 8) & 0xffff, ==, --bcount);
444         }
445     }
446     g_assert_cmpmem(tpm_msg, sizeof(tpm_msg), s->tpm_msg, sizeof(*s->tpm_msg));
447 
448     /* relinquish use of locality 0 */
449     writeb(TIS_REG(0, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_ACTIVE_LOCALITY);
450     access = readb(TIS_REG(0, TPM_TIS_REG_ACCESS));
451 }
452 
453 void tpm_tis_transfer(QTestState *s,
454                       const unsigned char *req, size_t req_size,
455                       unsigned char *rsp, size_t rsp_size)
456 {
457     uint32_t sts;
458     uint16_t bcount;
459     size_t i;
460 
461     /* request use of locality 0 */
462     qtest_writeb(s, TIS_REG(0, TPM_TIS_REG_ACCESS), TPM_TIS_ACCESS_REQUEST_USE);
463     qtest_writel(s, TIS_REG(0, TPM_TIS_REG_STS), TPM_TIS_STS_COMMAND_READY);
464 
465     sts = qtest_readl(s, TIS_REG(0, TPM_TIS_REG_STS));
466     bcount = (sts >> 8) & 0xffff;
467     g_assert_cmpint(bcount, >=, req_size);
468 
469     /* transmit command */
470     for (i = 0; i < req_size; i++) {
471         qtest_writeb(s, TIS_REG(0, TPM_TIS_REG_DATA_FIFO), req[i]);
472     }
473 
474     /* start processing */
475     qtest_writeb(s, TIS_REG(0, TPM_TIS_REG_STS), TPM_TIS_STS_TPM_GO);
476 
477     uint64_t end_time = g_get_monotonic_time() + 50 * G_TIME_SPAN_SECOND;
478     do {
479         sts = qtest_readl(s, TIS_REG(0, TPM_TIS_REG_STS));
480         if ((sts & TPM_TIS_STS_DATA_AVAILABLE) != 0) {
481             break;
482         }
483     } while (g_get_monotonic_time() < end_time);
484 
485     sts = qtest_readl(s, TIS_REG(0, TPM_TIS_REG_STS));
486     bcount = (sts >> 8) & 0xffff;
487 
488     memset(rsp, 0, rsp_size);
489     for (i = 0; i < bcount; i++) {
490         rsp[i] = qtest_readb(s, TIS_REG(0, TPM_TIS_REG_DATA_FIFO));
491     }
492 
493     /* relinquish use of locality 0 */
494     qtest_writeb(s, TIS_REG(0, TPM_TIS_REG_ACCESS),
495                  TPM_TIS_ACCESS_ACTIVE_LOCALITY);
496 }
497