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->dev, "Operation Canceled\n");
376 msleep(TPM_TIMEOUT); /* CHECK */
378 } while (time_before(jiffies, stop));
380 chip->ops->cancel(chip);
381 dev_err(chip->dev, "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->dev, "A TPM error (%d) occurred %s\n", err, desc);
419 #define TPM_INTERNAL_RESULT_SIZE 200
420 #define TPM_ORD_GET_CAP cpu_to_be32(101)
421 #define TPM_ORD_GET_RANDOM cpu_to_be32(70)
423 static const struct tpm_input_header tpm_getcap_header = {
424 .tag = TPM_TAG_RQU_COMMAND,
425 .length = cpu_to_be32(22),
426 .ordinal = TPM_ORD_GET_CAP
429 ssize_t tpm_getcap(struct device *dev, __be32 subcap_id, cap_t *cap,
432 struct tpm_cmd_t tpm_cmd;
434 struct tpm_chip *chip = dev_get_drvdata(dev);
436 tpm_cmd.header.in = tpm_getcap_header;
437 if (subcap_id == CAP_VERSION_1_1 || subcap_id == CAP_VERSION_1_2) {
438 tpm_cmd.params.getcap_in.cap = subcap_id;
439 /*subcap field not necessary */
440 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(0);
441 tpm_cmd.header.in.length -= cpu_to_be32(sizeof(__be32));
443 if (subcap_id == TPM_CAP_FLAG_PERM ||
444 subcap_id == TPM_CAP_FLAG_VOL)
445 tpm_cmd.params.getcap_in.cap = TPM_CAP_FLAG;
447 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
448 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
449 tpm_cmd.params.getcap_in.subcap = subcap_id;
451 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, desc);
453 *cap = tpm_cmd.params.getcap_out.cap;
457 void tpm_gen_interrupt(struct tpm_chip *chip)
459 struct tpm_cmd_t tpm_cmd;
462 tpm_cmd.header.in = tpm_getcap_header;
463 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
464 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
465 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_TIMEOUT;
467 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
468 "attempting to determine the timeouts");
470 EXPORT_SYMBOL_GPL(tpm_gen_interrupt);
472 #define TPM_ORD_STARTUP cpu_to_be32(153)
473 #define TPM_ST_CLEAR cpu_to_be16(1)
474 #define TPM_ST_STATE cpu_to_be16(2)
475 #define TPM_ST_DEACTIVATED cpu_to_be16(3)
476 static const struct tpm_input_header tpm_startup_header = {
477 .tag = TPM_TAG_RQU_COMMAND,
478 .length = cpu_to_be32(12),
479 .ordinal = TPM_ORD_STARTUP
482 static int tpm_startup(struct tpm_chip *chip, __be16 startup_type)
484 struct tpm_cmd_t start_cmd;
485 start_cmd.header.in = tpm_startup_header;
486 start_cmd.params.startup_in.startup_type = startup_type;
487 return tpm_transmit_cmd(chip, &start_cmd, TPM_INTERNAL_RESULT_SIZE,
488 "attempting to start the TPM");
491 int tpm_get_timeouts(struct tpm_chip *chip)
493 struct tpm_cmd_t tpm_cmd;
494 unsigned long new_timeout[4];
495 unsigned long old_timeout[4];
496 struct duration_t *duration_cap;
499 tpm_cmd.header.in = tpm_getcap_header;
500 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
501 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
502 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_TIMEOUT;
503 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE, NULL);
505 if (rc == TPM_ERR_INVALID_POSTINIT) {
506 /* The TPM is not started, we are the first to talk to it.
507 Execute a startup command. */
508 dev_info(chip->dev, "Issuing TPM_STARTUP");
509 if (tpm_startup(chip, TPM_ST_CLEAR))
512 tpm_cmd.header.in = tpm_getcap_header;
513 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
514 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
515 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_TIMEOUT;
516 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
521 "A TPM error (%zd) occurred attempting to determine the timeouts\n",
526 if (be32_to_cpu(tpm_cmd.header.out.return_code) != 0 ||
527 be32_to_cpu(tpm_cmd.header.out.length)
528 != sizeof(tpm_cmd.header.out) + sizeof(u32) + 4 * sizeof(u32))
531 old_timeout[0] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.a);
532 old_timeout[1] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.b);
533 old_timeout[2] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.c);
534 old_timeout[3] = be32_to_cpu(tpm_cmd.params.getcap_out.cap.timeout.d);
535 memcpy(new_timeout, old_timeout, sizeof(new_timeout));
538 * Provide ability for vendor overrides of timeout values in case
541 if (chip->ops->update_timeouts != NULL)
542 chip->vendor.timeout_adjusted =
543 chip->ops->update_timeouts(chip, new_timeout);
545 if (!chip->vendor.timeout_adjusted) {
546 /* Don't overwrite default if value is 0 */
547 if (new_timeout[0] != 0 && new_timeout[0] < 1000) {
550 /* timeouts in msec rather usec */
551 for (i = 0; i != ARRAY_SIZE(new_timeout); i++)
552 new_timeout[i] *= 1000;
553 chip->vendor.timeout_adjusted = true;
557 /* Report adjusted timeouts */
558 if (chip->vendor.timeout_adjusted) {
560 HW_ERR "Adjusting reported timeouts: A %lu->%luus B %lu->%luus C %lu->%luus D %lu->%luus\n",
561 old_timeout[0], new_timeout[0],
562 old_timeout[1], new_timeout[1],
563 old_timeout[2], new_timeout[2],
564 old_timeout[3], new_timeout[3]);
567 chip->vendor.timeout_a = usecs_to_jiffies(new_timeout[0]);
568 chip->vendor.timeout_b = usecs_to_jiffies(new_timeout[1]);
569 chip->vendor.timeout_c = usecs_to_jiffies(new_timeout[2]);
570 chip->vendor.timeout_d = usecs_to_jiffies(new_timeout[3]);
573 tpm_cmd.header.in = tpm_getcap_header;
574 tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
575 tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
576 tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_DURATION;
578 rc = tpm_transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
579 "attempting to determine the durations");
583 if (be32_to_cpu(tpm_cmd.header.out.return_code) != 0 ||
584 be32_to_cpu(tpm_cmd.header.out.length)
585 != sizeof(tpm_cmd.header.out) + sizeof(u32) + 3 * sizeof(u32))
588 duration_cap = &tpm_cmd.params.getcap_out.cap.duration;
589 chip->vendor.duration[TPM_SHORT] =
590 usecs_to_jiffies(be32_to_cpu(duration_cap->tpm_short));
591 chip->vendor.duration[TPM_MEDIUM] =
592 usecs_to_jiffies(be32_to_cpu(duration_cap->tpm_medium));
593 chip->vendor.duration[TPM_LONG] =
594 usecs_to_jiffies(be32_to_cpu(duration_cap->tpm_long));
596 /* The Broadcom BCM0102 chipset in a Dell Latitude D820 gets the above
597 * value wrong and apparently reports msecs rather than usecs. So we
598 * fix up the resulting too-small TPM_SHORT value to make things work.
599 * We also scale the TPM_MEDIUM and -_LONG values by 1000.
601 if (chip->vendor.duration[TPM_SHORT] < (HZ / 100)) {
602 chip->vendor.duration[TPM_SHORT] = HZ;
603 chip->vendor.duration[TPM_MEDIUM] *= 1000;
604 chip->vendor.duration[TPM_LONG] *= 1000;
605 chip->vendor.duration_adjusted = true;
606 dev_info(chip->dev, "Adjusting TPM timeout parameters.");
610 EXPORT_SYMBOL_GPL(tpm_get_timeouts);
612 #define TPM_ORD_CONTINUE_SELFTEST 83
613 #define CONTINUE_SELFTEST_RESULT_SIZE 10
615 static struct tpm_input_header continue_selftest_header = {
616 .tag = TPM_TAG_RQU_COMMAND,
617 .length = cpu_to_be32(10),
618 .ordinal = cpu_to_be32(TPM_ORD_CONTINUE_SELFTEST),
622 * tpm_continue_selftest -- run TPM's selftest
623 * @chip: TPM chip to use
625 * Returns 0 on success, < 0 in case of fatal error or a value > 0 representing
628 static int tpm_continue_selftest(struct tpm_chip *chip)
631 struct tpm_cmd_t cmd;
633 cmd.header.in = continue_selftest_header;
634 rc = tpm_transmit_cmd(chip, &cmd, CONTINUE_SELFTEST_RESULT_SIZE,
635 "continue selftest");
639 #define TPM_ORDINAL_PCRREAD cpu_to_be32(21)
640 #define READ_PCR_RESULT_SIZE 30
641 static struct tpm_input_header pcrread_header = {
642 .tag = TPM_TAG_RQU_COMMAND,
643 .length = cpu_to_be32(14),
644 .ordinal = TPM_ORDINAL_PCRREAD
647 int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
650 struct tpm_cmd_t cmd;
652 cmd.header.in = pcrread_header;
653 cmd.params.pcrread_in.pcr_idx = cpu_to_be32(pcr_idx);
654 rc = tpm_transmit_cmd(chip, &cmd, READ_PCR_RESULT_SIZE,
655 "attempting to read a pcr value");
658 memcpy(res_buf, cmd.params.pcrread_out.pcr_result,
664 * tpm_pcr_read - read a pcr value
665 * @chip_num: tpm idx # or ANY
666 * @pcr_idx: pcr idx to retrieve
667 * @res_buf: TPM_PCR value
668 * size of res_buf is 20 bytes (or NULL if you don't care)
670 * The TPM driver should be built-in, but for whatever reason it
671 * isn't, protect against the chip disappearing, by incrementing
672 * the module usage count.
674 int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf)
676 struct tpm_chip *chip;
679 chip = tpm_chip_find_get(chip_num);
682 rc = tpm_pcr_read_dev(chip, pcr_idx, res_buf);
686 EXPORT_SYMBOL_GPL(tpm_pcr_read);
689 * tpm_pcr_extend - extend pcr value with hash
690 * @chip_num: tpm idx # or AN&
691 * @pcr_idx: pcr idx to extend
692 * @hash: hash value used to extend pcr value
694 * The TPM driver should be built-in, but for whatever reason it
695 * isn't, protect against the chip disappearing, by incrementing
696 * the module usage count.
698 #define TPM_ORD_PCR_EXTEND cpu_to_be32(20)
699 #define EXTEND_PCR_RESULT_SIZE 34
700 static struct tpm_input_header pcrextend_header = {
701 .tag = TPM_TAG_RQU_COMMAND,
702 .length = cpu_to_be32(34),
703 .ordinal = TPM_ORD_PCR_EXTEND
706 int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
708 struct tpm_cmd_t cmd;
710 struct tpm_chip *chip;
712 chip = tpm_chip_find_get(chip_num);
716 cmd.header.in = pcrextend_header;
717 cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
718 memcpy(cmd.params.pcrextend_in.hash, hash, TPM_DIGEST_SIZE);
719 rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE,
720 "attempting extend a PCR value");
725 EXPORT_SYMBOL_GPL(tpm_pcr_extend);
728 * tpm_do_selftest - have the TPM continue its selftest and wait until it
729 * can receive further commands
730 * @chip: TPM chip to use
732 * Returns 0 on success, < 0 in case of fatal error or a value > 0 representing
735 int tpm_do_selftest(struct tpm_chip *chip)
739 unsigned int delay_msec = 100;
740 unsigned long duration;
741 struct tpm_cmd_t cmd;
743 duration = tpm_calc_ordinal_duration(chip, TPM_ORD_CONTINUE_SELFTEST);
745 loops = jiffies_to_msecs(duration) / delay_msec;
747 rc = tpm_continue_selftest(chip);
748 /* This may fail if there was no TPM driver during a suspend/resume
749 * cycle; some may return 10 (BAD_ORDINAL), others 28 (FAILEDSELFTEST)
755 /* Attempt to read a PCR value */
756 cmd.header.in = pcrread_header;
757 cmd.params.pcrread_in.pcr_idx = cpu_to_be32(0);
758 rc = tpm_transmit(chip, (u8 *) &cmd, READ_PCR_RESULT_SIZE);
759 /* Some buggy TPMs will not respond to tpm_tis_ready() for
760 * around 300ms while the self test is ongoing, keep trying
761 * until the self test duration expires. */
763 dev_info(chip->dev, HW_ERR "TPM command timed out during continue self test");
768 if (rc < TPM_HEADER_SIZE)
771 rc = be32_to_cpu(cmd.header.out.return_code);
772 if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
774 "TPM is disabled/deactivated (0x%X)\n", rc);
775 /* TPM is disabled and/or deactivated; driver can
776 * proceed and TPM does handle commands for
777 * suspend/resume correctly
781 if (rc != TPM_WARN_DOING_SELFTEST)
784 } while (--loops > 0);
788 EXPORT_SYMBOL_GPL(tpm_do_selftest);
790 int tpm_send(u32 chip_num, void *cmd, size_t buflen)
792 struct tpm_chip *chip;
795 chip = tpm_chip_find_get(chip_num);
799 rc = tpm_transmit_cmd(chip, cmd, buflen, "attempting tpm_cmd");
804 EXPORT_SYMBOL_GPL(tpm_send);
806 static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
807 bool check_cancel, bool *canceled)
809 u8 status = chip->ops->status(chip);
812 if ((status & mask) == mask)
814 if (check_cancel && chip->ops->req_canceled(chip, status)) {
821 int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
822 wait_queue_head_t *queue, bool check_cancel)
827 bool canceled = false;
829 /* check current status */
830 status = chip->ops->status(chip);
831 if ((status & mask) == mask)
834 stop = jiffies + timeout;
836 if (chip->vendor.irq) {
838 timeout = stop - jiffies;
839 if ((long)timeout <= 0)
841 rc = wait_event_interruptible_timeout(*queue,
842 wait_for_tpm_stat_cond(chip, mask, check_cancel,
850 if (rc == -ERESTARTSYS && freezing(current)) {
851 clear_thread_flag(TIF_SIGPENDING);
857 status = chip->ops->status(chip);
858 if ((status & mask) == mask)
860 } while (time_before(jiffies, stop));
864 EXPORT_SYMBOL_GPL(wait_for_tpm_stat);
866 #define TPM_ORD_SAVESTATE cpu_to_be32(152)
867 #define SAVESTATE_RESULT_SIZE 10
869 static struct tpm_input_header savestate_header = {
870 .tag = TPM_TAG_RQU_COMMAND,
871 .length = cpu_to_be32(10),
872 .ordinal = TPM_ORD_SAVESTATE
876 * We are about to suspend. Save the TPM state
877 * so that it can be restored.
879 int tpm_pm_suspend(struct device *dev)
881 struct tpm_chip *chip = dev_get_drvdata(dev);
882 struct tpm_cmd_t cmd;
885 u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
890 /* for buggy tpm, flush pcrs with extend to selected dummy */
891 if (tpm_suspend_pcr) {
892 cmd.header.in = pcrextend_header;
893 cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(tpm_suspend_pcr);
894 memcpy(cmd.params.pcrextend_in.hash, dummy_hash,
896 rc = tpm_transmit_cmd(chip, &cmd, EXTEND_PCR_RESULT_SIZE,
897 "extending dummy pcr before suspend");
900 /* now do the actual savestate */
901 for (try = 0; try < TPM_RETRY; try++) {
902 cmd.header.in = savestate_header;
903 rc = tpm_transmit_cmd(chip, &cmd, SAVESTATE_RESULT_SIZE, NULL);
906 * If the TPM indicates that it is too busy to respond to
907 * this command then retry before giving up. It can take
908 * several seconds for this TPM to be ready.
910 * This can happen if the TPM has already been sent the
911 * SaveState command before the driver has loaded. TCG 1.2
912 * specification states that any communication after SaveState
913 * may cause the TPM to invalidate previously saved state.
915 if (rc != TPM_WARN_RETRY)
917 msleep(TPM_TIMEOUT_RETRY);
922 "Error (%d) sending savestate before suspend\n", rc);
924 dev_warn(chip->dev, "TPM savestate took %dms\n",
925 try * TPM_TIMEOUT_RETRY);
929 EXPORT_SYMBOL_GPL(tpm_pm_suspend);
932 * Resume from a power safe. The BIOS already restored
935 int tpm_pm_resume(struct device *dev)
937 struct tpm_chip *chip = dev_get_drvdata(dev);
944 EXPORT_SYMBOL_GPL(tpm_pm_resume);
946 #define TPM_GETRANDOM_RESULT_SIZE 18
947 static struct tpm_input_header tpm_getrandom_header = {
948 .tag = TPM_TAG_RQU_COMMAND,
949 .length = cpu_to_be32(14),
950 .ordinal = TPM_ORD_GET_RANDOM
954 * tpm_get_random() - Get random bytes from the tpm's RNG
955 * @chip_num: A specific chip number for the request or TPM_ANY_NUM
956 * @out: destination buffer for the random bytes
957 * @max: the max number of bytes to write to @out
959 * Returns < 0 on error and the number of bytes read on success
961 int tpm_get_random(u32 chip_num, u8 *out, size_t max)
963 struct tpm_chip *chip;
964 struct tpm_cmd_t tpm_cmd;
965 u32 recd, num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA);
966 int err, total = 0, retries = 5;
969 if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
972 chip = tpm_chip_find_get(chip_num);
977 tpm_cmd.header.in = tpm_getrandom_header;
978 tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
980 err = tpm_transmit_cmd(chip, &tpm_cmd,
981 TPM_GETRANDOM_RESULT_SIZE + num_bytes,
982 "attempting get random");
986 recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
987 memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
992 } while (retries-- && total < max);
995 return total ? total : -EIO;
997 EXPORT_SYMBOL_GPL(tpm_get_random);
999 MODULE_AUTHOR("Leendert van Doorn (leendert@watson.ibm.com)");
1000 MODULE_DESCRIPTION("TPM Driver");
1001 MODULE_VERSION("2.0");
1002 MODULE_LICENSE("GPL");