2 * Copyright (C) 2004 IBM Corporation
3 * Copyright (C) 2014 Intel Corporation
6 * Leendert van Doorn <leendert@watson.ibm.com>
7 * Dave Safford <safford@watson.ibm.com>
8 * Reiner Sailer <sailer@watson.ibm.com>
9 * Kylene Hall <kjhall@us.ibm.com>
11 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
13 * Device driver for TCG/TCPA TPM (trusted platform module).
14 * Specifications at www.trustedcomputinggroup.org
16 * This program is free software; you can redistribute it and/or
17 * modify it under the terms of the GNU General Public License as
18 * published by the Free Software Foundation, version 2 of the
21 * Note, the TPM chip is not interrupt driven (only polling)
22 * and can have very long timeouts (minutes!). Hence the unusual
27 #include <linux/poll.h>
28 #include <linux/slab.h>
29 #include <linux/mutex.h>
30 #include <linux/spinlock.h>
31 #include <linux/freezer.h>
34 #include "tpm_eventlog.h"
36 #define TPM_MAX_ORDINAL 243
37 #define TSC_MAX_ORDINAL 12
38 #define TPM_PROTECTED_COMMAND 0x00
39 #define TPM_CONNECTION_COMMAND 0x40
42 * Bug workaround - some TPM's don't flush the most
43 * recently changed pcr on suspend, so force the flush
44 * with an extend to the selected _unused_ non-volatile pcr.
46 static int tpm_suspend_pcr;
47 module_param_named(suspend_pcr, tpm_suspend_pcr, uint, 0644);
48 MODULE_PARM_DESC(suspend_pcr,
49 "PCR to use for dummy writes to faciltate flush on suspend.");
52 * Array with one entry per ordinal defining the maximum amount
53 * of time the chip could take to return the result. The ordinal
54 * designation of short, medium or long is defined in a table in
55 * TCG Specification TPM Main Part 2 TPM Structures Section 17. The
56 * values of the SHORT, MEDIUM, and LONG durations are retrieved
57 * from the chip during initialization with a call to tpm_get_timeouts.
59 static const u8 tpm_ordinal_duration[TPM_MAX_ORDINAL] = {
60 TPM_UNDEFINED, /* 0 */
65 TPM_UNDEFINED, /* 5 */
115 TPM_UNDEFINED, /* 55 */
135 TPM_UNDEFINED, /* 75 */
145 TPM_UNDEFINED, /* 85 */
155 TPM_UNDEFINED, /* 95 */
160 TPM_MEDIUM, /* 100 */
165 TPM_UNDEFINED, /* 105 */
195 TPM_UNDEFINED, /* 135 */
205 TPM_UNDEFINED, /* 145 */
215 TPM_UNDEFINED, /* 155 */
225 TPM_UNDEFINED, /* 165 */
235 TPM_UNDEFINED, /* 175 */
240 TPM_MEDIUM, /* 180 */
245 TPM_MEDIUM, /* 185 */
250 TPM_UNDEFINED, /* 190 */
255 TPM_UNDEFINED, /* 195 */
270 TPM_MEDIUM, /* 210 */
275 TPM_UNDEFINED, /* 215 */
285 TPM_UNDEFINED, /* 225 */
295 TPM_UNDEFINED, /* 235 */
306 * Returns max number of jiffies to wait
308 unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip,
311 int duration_idx = TPM_UNDEFINED;
313 u8 category = (ordinal >> 24) & 0xFF;
315 if ((category == TPM_PROTECTED_COMMAND && ordinal < TPM_MAX_ORDINAL) ||
316 (category == TPM_CONNECTION_COMMAND && ordinal < TSC_MAX_ORDINAL))
317 duration_idx = tpm_ordinal_duration[ordinal];
319 if (duration_idx != TPM_UNDEFINED)
320 duration = chip->vendor.duration[duration_idx];
326 EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);
329 * Internal kernel interface to transmit TPM commands
331 ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
338 if (bufsiz > TPM_BUFSIZE)
339 bufsiz = TPM_BUFSIZE;
341 count = be32_to_cpu(*((__be32 *) (buf + 2)));
342 ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
345 if (count > bufsiz) {
347 "invalid count value %x %zx\n", count, bufsiz);
351 mutex_lock(&chip->tpm_mutex);
353 rc = chip->ops->send(chip, (u8 *) buf, count);
356 "tpm_transmit: tpm_send: error %zd\n", rc);
360 if (chip->vendor.irq)
363 stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
365 u8 status = chip->ops->status(chip);
366 if ((status & chip->ops->req_complete_mask) ==
367 chip->ops->req_complete_val)
370 if (chip->ops->req_canceled(chip, status)) {
371 dev_err(chip->pdev, "Operation Canceled\n");
376 msleep(TPM_TIMEOUT); /* CHECK */
378 } while (time_before(jiffies, stop));
380 chip->ops->cancel(chip);
381 dev_err(chip->pdev, "Operation Timed out\n");
386 rc = chip->ops->recv(chip, (u8 *) buf, bufsiz);
389 "tpm_transmit: tpm_recv: error %zd\n", rc);
391 mutex_unlock(&chip->tpm_mutex);
395 #define TPM_DIGEST_SIZE 20
396 #define TPM_RET_CODE_IDX 6
398 ssize_t tpm_transmit_cmd(struct tpm_chip *chip, void *cmd,
399 int len, const char *desc)
401 struct tpm_output_header *header;
404 len = tpm_transmit(chip, (u8 *) cmd, len);
407 else if (len < TPM_HEADER_SIZE)
412 err = be32_to_cpu(header->return_code);
413 if (err != 0 && desc)
414 dev_err(chip->pdev, "A TPM error (%d) occurred %s\n", err,
420 #define TPM_INTERNAL_RESULT_SIZE 200
421 #define TPM_ORD_GET_CAP cpu_to_be32(101)
422 #define TPM_ORD_GET_RANDOM cpu_to_be32(70)
424 static const struct tpm_input_header tpm_getcap_header = {
425 .tag = TPM_TAG_RQU_COMMAND,
426 .length = cpu_to_be32(22),
427 .ordinal = TPM_ORD_GET_CAP
430 ssize_t tpm_getcap(struct device *dev, __be32 subcap_id, cap_t *cap,
433 struct tpm_cmd_t tpm_cmd;
435 struct tpm_chip *chip = dev_get_drvdata(dev);
437 tpm_cmd.header.in = tpm_getcap_header;
438 if (subcap_id == CAP_VERSION_1_1 || subcap_id == CAP_VERSION_1_2) {
439 tpm_cmd.params.getcap_in.cap = subcap_id;
440 /*subcap field not necessary */
441 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(0);
442 tpm_cmd.header.in.length -= cpu_to_be32(sizeof(__be32));
444 if (subcap_id == TPM_CAP_FLAG_PERM ||
445 subcap_id == TPM_CAP_FLAG_VOL)
446 tpm_cmd.params.getcap_in.cap = TPM_CAP_FLAG;
448 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
449 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
450 tpm_cmd.params.getcap_in.subcap = subcap_id;
452 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, desc);
454 *cap = tpm_cmd.params.getcap_out.cap;
458 void tpm_gen_interrupt(struct tpm_chip *chip)
460 struct tpm_cmd_t tpm_cmd;
463 tpm_cmd.header.in = tpm_getcap_header;
464 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
465 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
466 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_TIMEOUT;
468 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
469 "attempting to determine the timeouts");
471 EXPORT_SYMBOL_GPL(tpm_gen_interrupt);
473 #define TPM_ORD_STARTUP cpu_to_be32(153)
474 #define TPM_ST_CLEAR cpu_to_be16(1)
475 #define TPM_ST_STATE cpu_to_be16(2)
476 #define TPM_ST_DEACTIVATED cpu_to_be16(3)
477 static const struct tpm_input_header tpm_startup_header = {
478 .tag = TPM_TAG_RQU_COMMAND,
479 .length = cpu_to_be32(12),
480 .ordinal = TPM_ORD_STARTUP
483 static int tpm_startup(struct tpm_chip *chip, __be16 startup_type)
485 struct tpm_cmd_t start_cmd;
486 start_cmd.header.in = tpm_startup_header;
487 start_cmd.params.startup_in.startup_type = startup_type;
488 return tpm_transmit_cmd(chip, &start_cmd, TPM_INTERNAL_RESULT_SIZE,
489 "attempting to start the TPM");
492 int tpm_get_timeouts(struct tpm_chip *chip)
494 struct tpm_cmd_t tpm_cmd;
495 unsigned long new_timeout[4];
496 unsigned long old_timeout[4];
497 struct duration_t *duration_cap;
500 tpm_cmd.header.in = tpm_getcap_header;
501 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
502 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
503 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_TIMEOUT;
504 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, NULL);
506 if (rc == TPM_ERR_INVALID_POSTINIT) {
507 /* The TPM is not started, we are the first to talk to it.
508 Execute a startup command. */
509 dev_info(chip->pdev, "Issuing TPM_STARTUP");
510 if (tpm_startup(chip, TPM_ST_CLEAR))
513 tpm_cmd.header.in = tpm_getcap_header;
514 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
515 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
516 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_TIMEOUT;
517 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
522 "A TPM error (%zd) occurred attempting to determine the timeouts\n",
527 if (be32_to_cpu(tpm_cmd.header.out.return_code) != 0 ||
528 be32_to_cpu(tpm_cmd.header.out.length)
529 != sizeof(tpm_cmd.header.out) + sizeof(u32) + 4 * sizeof(u32))
532 old_timeout[0] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.a);
533 old_timeout[1] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.b);
534 old_timeout[2] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.c);
535 old_timeout[3] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.d);
536 memcpy(new_timeout, old_timeout, sizeof(new_timeout));
539 * Provide ability for vendor overrides of timeout values in case
542 if (chip->ops->update_timeouts != NULL)
543 chip->vendor.timeout_adjusted =
544 chip->ops->update_timeouts(chip, new_timeout);
546 if (!chip->vendor.timeout_adjusted) {
547 /* Don't overwrite default if value is 0 */
548 if (new_timeout[0] != 0 && new_timeout[0] < 1000) {
551 /* timeouts in msec rather usec */
552 for (i = 0; i != ARRAY_SIZE(new_timeout); i++)
553 new_timeout[i] *= 1000;
554 chip->vendor.timeout_adjusted = true;
558 /* Report adjusted timeouts */
559 if (chip->vendor.timeout_adjusted) {
561 HW_ERR "Adjusting reported timeouts: A %lu->%luus B %lu->%luus C %lu->%luus D %lu->%luus\n",
562 old_timeout[0], new_timeout[0],
563 old_timeout[1], new_timeout[1],
564 old_timeout[2], new_timeout[2],
565 old_timeout[3], new_timeout[3]);
568 chip->vendor.timeout_a = usecs_to_jiffies(new_timeout[0]);
569 chip->vendor.timeout_b = usecs_to_jiffies(new_timeout[1]);
570 chip->vendor.timeout_c = usecs_to_jiffies(new_timeout[2]);
571 chip->vendor.timeout_d = usecs_to_jiffies(new_timeout[3]);
574 tpm_cmd.header.in = tpm_getcap_header;
575 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
576 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
577 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_DURATION;
579 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
580 "attempting to determine the durations");
584 if (be32_to_cpu(tpm_cmd.header.out.return_code) != 0 ||
585 be32_to_cpu(tpm_cmd.header.out.length)
586 != sizeof(tpm_cmd.header.out) + sizeof(u32) + 3 * sizeof(u32))
589 duration_cap = &tpm_cmd.params.getcap_out.cap.duration;
590 chip->vendor.duration[TPM_SHORT] =
591 usecs_to_jiffies(be32_to_cpu(duration_cap->tpm_short));
592 chip->vendor.duration[TPM_MEDIUM] =
593 usecs_to_jiffies(be32_to_cpu(duration_cap->tpm_medium));
594 chip->vendor.duration[TPM_LONG] =
595 usecs_to_jiffies(be32_to_cpu(duration_cap->tpm_long));
597 /* The Broadcom BCM0102 chipset in a Dell Latitude D820 gets the above
598 * value wrong and apparently reports msecs rather than usecs. So we
599 * fix up the resulting too-small TPM_SHORT value to make things work.
600 * We also scale the TPM_MEDIUM and -_LONG values by 1000.
602 if (chip->vendor.duration[TPM_SHORT] < (HZ / 100)) {
603 chip->vendor.duration[TPM_SHORT] = HZ;
604 chip->vendor.duration[TPM_MEDIUM] *= 1000;
605 chip->vendor.duration[TPM_LONG] *= 1000;
606 chip->vendor.duration_adjusted = true;
607 dev_info(chip->pdev, "Adjusting TPM timeout parameters.");
611 EXPORT_SYMBOL_GPL(tpm_get_timeouts);
613 #define TPM_ORD_CONTINUE_SELFTEST 83
614 #define CONTINUE_SELFTEST_RESULT_SIZE 10
616 static struct tpm_input_header continue_selftest_header = {
617 .tag = TPM_TAG_RQU_COMMAND,
618 .length = cpu_to_be32(10),
619 .ordinal = cpu_to_be32(TPM_ORD_CONTINUE_SELFTEST),
623 * tpm_continue_selftest -- run TPM's selftest
624 * @chip: TPM chip to use
626 * Returns 0 on success, < 0 in case of fatal error or a value > 0 representing
629 static int tpm_continue_selftest(struct tpm_chip *chip)
632 struct tpm_cmd_t cmd;
634 cmd.header.in = continue_selftest_header;
635 rc = tpm_transmit_cmd(chip, &cmd, CONTINUE_SELFTEST_RESULT_SIZE,
636 "continue selftest");
640 #define TPM_ORDINAL_PCRREAD cpu_to_be32(21)
641 #define READ_PCR_RESULT_SIZE 30
642 static struct tpm_input_header pcrread_header = {
643 .tag = TPM_TAG_RQU_COMMAND,
644 .length = cpu_to_be32(14),
645 .ordinal = TPM_ORDINAL_PCRREAD
648 int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
651 struct tpm_cmd_t cmd;
653 cmd.header.in = pcrread_header;
654 cmd.params.pcrread_in.pcr_idx = cpu_to_be32(pcr_idx);
655 rc = tpm_transmit_cmd(chip, &cmd, READ_PCR_RESULT_SIZE,
656 "attempting to read a pcr value");
659 memcpy(res_buf, cmd.params.pcrread_out.pcr_result,
665 * tpm_pcr_read - read a pcr value
666 * @chip_num: tpm idx # or ANY
667 * @pcr_idx: pcr idx to retrieve
668 * @res_buf: TPM_PCR value
669 * size of res_buf is 20 bytes (or NULL if you don't care)
671 * The TPM driver should be built-in, but for whatever reason it
672 * isn't, protect against the chip disappearing, by incrementing
673 * the module usage count.
675 int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf)
677 struct tpm_chip *chip;
680 chip = tpm_chip_find_get(chip_num);
683 rc = tpm_pcr_read_dev(chip, pcr_idx, res_buf);
687 EXPORT_SYMBOL_GPL(tpm_pcr_read);
690 * tpm_pcr_extend - extend pcr value with hash
691 * @chip_num: tpm idx # or AN&
692 * @pcr_idx: pcr idx to extend
693 * @hash: hash value used to extend pcr value
695 * The TPM driver should be built-in, but for whatever reason it
696 * isn't, protect against the chip disappearing, by incrementing
697 * the module usage count.
699 #define TPM_ORD_PCR_EXTEND cpu_to_be32(20)
700 #define EXTEND_PCR_RESULT_SIZE 34
701 static struct tpm_input_header pcrextend_header = {
702 .tag = TPM_TAG_RQU_COMMAND,
703 .length = cpu_to_be32(34),
704 .ordinal = TPM_ORD_PCR_EXTEND
707 int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
709 struct tpm_cmd_t cmd;
711 struct tpm_chip *chip;
713 chip = tpm_chip_find_get(chip_num);
717 cmd.header.in = pcrextend_header;
718 cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
719 memcpy(cmd.params.pcrextend_in.hash, hash, TPM_DIGEST_SIZE);
720 rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE,
721 "attempting extend a PCR value");
726 EXPORT_SYMBOL_GPL(tpm_pcr_extend);
729 * tpm_do_selftest - have the TPM continue its selftest and wait until it
730 * can receive further commands
731 * @chip: TPM chip to use
733 * Returns 0 on success, < 0 in case of fatal error or a value > 0 representing
736 int tpm_do_selftest(struct tpm_chip *chip)
740 unsigned int delay_msec = 100;
741 unsigned long duration;
742 struct tpm_cmd_t cmd;
744 duration = tpm_calc_ordinal_duration(chip, TPM_ORD_CONTINUE_SELFTEST);
746 loops = jiffies_to_msecs(duration) / delay_msec;
748 rc = tpm_continue_selftest(chip);
749 /* This may fail if there was no TPM driver during a suspend/resume
750 * cycle; some may return 10 (BAD_ORDINAL), others 28 (FAILEDSELFTEST)
756 /* Attempt to read a PCR value */
757 cmd.header.in = pcrread_header;
758 cmd.params.pcrread_in.pcr_idx = cpu_to_be32(0);
759 rc = tpm_transmit(chip, (u8 *) &cmd, READ_PCR_RESULT_SIZE);
760 /* Some buggy TPMs will not respond to tpm_tis_ready() for
761 * around 300ms while the self test is ongoing, keep trying
762 * until the self test duration expires. */
764 dev_info(chip->pdev, HW_ERR "TPM command timed out during continue self test");
769 if (rc < TPM_HEADER_SIZE)
772 rc = be32_to_cpu(cmd.header.out.return_code);
773 if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
775 "TPM is disabled/deactivated (0x%X)\n", rc);
776 /* TPM is disabled and/or deactivated; driver can
777 * proceed and TPM does handle commands for
778 * suspend/resume correctly
782 if (rc != TPM_WARN_DOING_SELFTEST)
785 } while (--loops > 0);
789 EXPORT_SYMBOL_GPL(tpm_do_selftest);
791 int tpm_send(u32 chip_num, void *cmd, size_t buflen)
793 struct tpm_chip *chip;
796 chip = tpm_chip_find_get(chip_num);
800 rc = tpm_transmit_cmd(chip, cmd, buflen, "attempting tpm_cmd");
805 EXPORT_SYMBOL_GPL(tpm_send);
807 static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
808 bool check_cancel, bool *canceled)
810 u8 status = chip->ops->status(chip);
813 if ((status & mask) == mask)
815 if (check_cancel && chip->ops->req_canceled(chip, status)) {
822 int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
823 wait_queue_head_t *queue, bool check_cancel)
828 bool canceled = false;
830 /* check current status */
831 status = chip->ops->status(chip);
832 if ((status & mask) == mask)
835 stop = jiffies + timeout;
837 if (chip->vendor.irq) {
839 timeout = stop - jiffies;
840 if ((long)timeout <= 0)
842 rc = wait_event_interruptible_timeout(*queue,
843 wait_for_tpm_stat_cond(chip, mask, check_cancel,
851 if (rc == -ERESTARTSYS && freezing(current)) {
852 clear_thread_flag(TIF_SIGPENDING);
858 status = chip->ops->status(chip);
859 if ((status & mask) == mask)
861 } while (time_before(jiffies, stop));
865 EXPORT_SYMBOL_GPL(wait_for_tpm_stat);
867 #define TPM_ORD_SAVESTATE cpu_to_be32(152)
868 #define SAVESTATE_RESULT_SIZE 10
870 static struct tpm_input_header savestate_header = {
871 .tag = TPM_TAG_RQU_COMMAND,
872 .length = cpu_to_be32(10),
873 .ordinal = TPM_ORD_SAVESTATE
877 * We are about to suspend. Save the TPM state
878 * so that it can be restored.
880 int tpm_pm_suspend(struct device *dev)
882 struct tpm_chip *chip = dev_get_drvdata(dev);
883 struct tpm_cmd_t cmd;
886 u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
891 /* for buggy tpm, flush pcrs with extend to selected dummy */
892 if (tpm_suspend_pcr) {
893 cmd.header.in = pcrextend_header;
894 cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(tpm_suspend_pcr);
895 memcpy(cmd.params.pcrextend_in.hash, dummy_hash,
897 rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE,
898 "extending dummy pcr before suspend");
901 /* now do the actual savestate */
902 for (try = 0; try < TPM_RETRY; try++) {
903 cmd.header.in = savestate_header;
904 rc = tpm_transmit_cmd(chip, &cmd, SAVESTATE_RESULT_SIZE, NULL);
907 * If the TPM indicates that it is too busy to respond to
908 * this command then retry before giving up. It can take
909 * several seconds for this TPM to be ready.
911 * This can happen if the TPM has already been sent the
912 * SaveState command before the driver has loaded. TCG 1.2
913 * specification states that any communication after SaveState
914 * may cause the TPM to invalidate previously saved state.
916 if (rc != TPM_WARN_RETRY)
918 msleep(TPM_TIMEOUT_RETRY);
923 "Error (%d) sending savestate before suspend\n", rc);
925 dev_warn(chip->pdev, "TPM savestate took %dms\n",
926 try * TPM_TIMEOUT_RETRY);
930 EXPORT_SYMBOL_GPL(tpm_pm_suspend);
933 * Resume from a power safe. The BIOS already restored
936 int tpm_pm_resume(struct device *dev)
938 struct tpm_chip *chip = dev_get_drvdata(dev);
945 EXPORT_SYMBOL_GPL(tpm_pm_resume);
947 #define TPM_GETRANDOM_RESULT_SIZE 18
948 static struct tpm_input_header tpm_getrandom_header = {
949 .tag = TPM_TAG_RQU_COMMAND,
950 .length = cpu_to_be32(14),
951 .ordinal = TPM_ORD_GET_RANDOM
955 * tpm_get_random() - Get random bytes from the tpm's RNG
956 * @chip_num: A specific chip number for the request or TPM_ANY_NUM
957 * @out: destination buffer for the random bytes
958 * @max: the max number of bytes to write to @out
960 * Returns < 0 on error and the number of bytes read on success
962 int tpm_get_random(u32 chip_num, u8 *out, size_t max)
964 struct tpm_chip *chip;
965 struct tpm_cmd_t tpm_cmd;
966 u32 recd, num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA);
967 int err, total = 0, retries = 5;
970 if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
973 chip = tpm_chip_find_get(chip_num);
978 tpm_cmd.header.in = tpm_getrandom_header;
979 tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
981 err = tpm_transmit_cmd(chip, &tpm_cmd,
982 TPM_GETRANDOM_RESULT_SIZE + num_bytes,
983 "attempting get random");
987 recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
988 memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
993 } while (retries-- && total < max);
996 return total ? total : -EIO;
998 EXPORT_SYMBOL_GPL(tpm_get_random);
1000 MODULE_AUTHOR("Leendert van Doorn (leendert@watson.ibm.com)");
1001 MODULE_DESCRIPTION("TPM Driver");
1002 MODULE_VERSION("2.0");
1003 MODULE_LICENSE("GPL");