tpm: Add TPM command library

TPM command library implements a subset of TPM commands defined in TCG
Main Specification 1.2 that are useful for implementing secure boot.
More TPM commands could be added out of necessity.

You may exercise these commands through the 'tpm' command.  However, the
raw TPM commands are too primitive for writing secure boot in command
interpreter scripts; so the 'tpm' command also provides helper functions
to make scripting easier.

For example, to define a counter in TPM non-volatile storage and
initialize it to zero:

$ tpm init
$ tpm startup TPM_ST_CLEAR
$ tpm nv_define d 0x1001 0x1
$ tpm nv_write d 0x1001 0

And then increment the counter by one:

$ tpm nv_read d 0x1001 i
$ setexpr.l i $i + 1
$ tpm nv_write d 0x1001 $i

Signed-off-by: Che-Liang Chiou <clchiou@chromium.org>

5 files changed, 1419 insertions, 142 deletions

diff --git a/common/cmd_tpm.c b/common/cmd_tpm.c
index 0970a6f..46fae18 100644
--- a/common/cmd_tpm.c
+++ b/common/cmd_tpm.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011 The Chromium OS Authors.
+ * Copyright (c) 2013 The Chromium OS Authors.
  *
  * See file CREDITS for list of people who contributed to this
  * project.
@@ -22,163 +22,652 @@
 
 #include <common.h>
 #include <command.h>
+#include <malloc.h>
 #include <tpm.h>
+#include <asm/unaligned.h>
+#include <linux/string.h>
 
-#define MAX_TRANSACTION_SIZE 30
+/**
+ * Print a byte string in hexdecimal format, 16-bytes per line.
+ *
+ * @param data		byte string to be printed
+ * @param count		number of bytes to be printed
+ */
+static void print_byte_string(uint8_t *data, size_t count)
+{
+	int i, print_newline = 0;
 
-/*
- * tpm_write() expects a variable number of parameters: the internal address
- * followed by data to write, byte by byte.
+	for (i = 0; i < count; i++) {
+		printf(" %02x", data[i]);
+		print_newline = (i % 16 == 15);
+		if (print_newline)
+			putc('\n');
+	}
+	/* Avoid duplicated newline at the end */
+	if (!print_newline)
+		putc('\n');
+}
+
+/**
+ * Convert a text string of hexdecimal values into a byte string.
  *
- * Returns 0 on success or -1 on errors (wrong arguments or TPM failure).
+ * @param bytes		text string of hexdecimal values with no space
+ *			between them
+ * @param data		output buffer for byte string.  The caller has to make
+ *			sure it is large enough for storing the output.  If
+ *			NULL is passed, a large enough buffer will be allocated,
+ *			and the caller must free it.
+ * @param count_ptr	output variable for the length of byte string
+ * @return pointer to output buffer
  */
-static int tpm_process(int argc, char * const argv[], cmd_tbl_t *cmdtp)
-{
-	u8 tpm_buffer[MAX_TRANSACTION_SIZE];
-	u32 write_size, read_size;
-	char *p;
-	int rv = -1;
-
-	for (write_size = 0; write_size < argc; write_size++) {
-		u32 datum = simple_strtoul(argv[write_size], &p, 0);
-		if (*p || (datum > 0xff)) {
-			printf("\n%s: bad data value\n\n", argv[write_size]);
-			cmd_usage(cmdtp);
-			return rv;
-		}
-		tpm_buffer[write_size] = (u8)datum;
+static void *parse_byte_string(char *bytes, uint8_t *data, size_t *count_ptr)
+{
+	char byte[3];
+	size_t count, length;
+	int i;
+
+	length = strlen(bytes);
+	count = length / 2;
+
+	if (!data)
+		data = malloc(count);
+	if (!data)
+		return NULL;
+
+	byte[2] = '\0';
+	for (i = 0; i < length; i += 2) {
+		byte[0] = bytes[i];
+		byte[1] = bytes[i + 1];
+		data[i / 2] = (uint8_t)simple_strtoul(byte, NULL, 16);
 	}
 
-	read_size = sizeof(tpm_buffer);
-	if (!tis_sendrecv(tpm_buffer, write_size, tpm_buffer, &read_size)) {
-		int i;
-		puts("Got TPM response:\n");
-		for (i = 0; i < read_size; i++)
-			printf(" %2.2x", tpm_buffer[i]);
-		puts("\n");
-		rv = 0;
-	} else {
-		puts("tpm command failed\n");
+	if (count_ptr)
+		*count_ptr = count;
+
+	return data;
+}
+
+/**
+ * Convert TPM command return code to U-Boot command error codes.
+ *
+ * @param return_code	TPM command return code
+ * @return value of enum command_ret_t
+ */
+static int convert_return_code(uint32_t return_code)
+{
+	if (return_code)
+		return CMD_RET_FAILURE;
+	else
+		return CMD_RET_SUCCESS;
+}
+
+/**
+ * Return number of values defined by a type string.
+ *
+ * @param type_str	type string
+ * @return number of values of type string
+ */
+static int type_string_get_num_values(const char *type_str)
+{
+	return strlen(type_str);
+}
+
+/**
+ * Return total size of values defined by a type string.
+ *
+ * @param type_str	type string
+ * @return total size of values of type string, or 0 if type string
+ *  contains illegal type character.
+ */
+static size_t type_string_get_space_size(const char *type_str)
+{
+	size_t size;
+
+	for (size = 0; *type_str; type_str++) {
+		switch (*type_str) {
+		case 'b':
+			size += 1;
+			break;
+		case 'w':
+			size += 2;
+			break;
+		case 'd':
+			size += 4;
+			break;
+		default:
+			return 0;
+		}
 	}
-	return rv;
+
+	return size;
 }
 
-#define CHECK(exp) do {							\
-		int _rv = exp;						\
-		if (_rv) {						\
-			printf("CHECK: %s %d %x\n", #exp, __LINE__, _rv);\
-		}							\
-	} while (0)
+/**
+ * Allocate a buffer large enough to hold values defined by a type
+ * string.  The caller has to free the buffer.
+ *
+ * @param type_str	type string
+ * @param count		pointer for storing size of buffer
+ * @return pointer to buffer or NULL on error
+ */
+static void *type_string_alloc(const char *type_str, uint32_t *count)
+{
+	void *data;
+	size_t size;
+
+	size = type_string_get_space_size(type_str);
+	if (!size)
+		return NULL;
+	data = malloc(size);
+	if (data)
+		*count = size;
 
-static int tpm_process_stress(int repeat_count)
+	return data;
+}
+
+/**
+ * Pack values defined by a type string into a buffer.  The buffer must have
+ * large enough space.
+ *
+ * @param type_str	type string
+ * @param values	text strings of values to be packed
+ * @param data		output buffer of values
+ * @return 0 on success, non-0 on error
+ */
+static int type_string_pack(const char *type_str, char * const values[],
+		uint8_t *data)
 {
-	int i;
-	int rv = 0;
-	u8 request[] = {0x0, 0xc1,
-			0x0, 0x0, 0x0, 0x16,
-			0x0, 0x0, 0x0, 0x65,
-			0x0, 0x0, 0x0, 0x4,
-			0x0, 0x0, 0x0, 0x4,
-			0x0, 0x0, 0x1, 0x9};
-	u8 response[MAX_TRANSACTION_SIZE];
-	u32 rlength = MAX_TRANSACTION_SIZE;
-
-	CHECK(tis_init());
-
-	for (i = 0; i < repeat_count; i++) {
-		CHECK(tis_open());
-		rv = tis_sendrecv(request, sizeof(request), response, &rlength);
-		if (rv) {
-			printf("tpm test failed at step %d with 0x%x\n", i, rv);
-			CHECK(tis_close());
+	size_t offset;
+	uint32_t value;
+
+	for (offset = 0; *type_str; type_str++, values++) {
+		value = simple_strtoul(values[0], NULL, 0);
+		switch (*type_str) {
+		case 'b':
+			data[offset] = value;
+			offset += 1;
+			break;
+		case 'w':
+			put_unaligned_be16(value, data + offset);
+			offset += 2;
+			break;
+		case 'd':
+			put_unaligned_be32(value, data + offset);
+			offset += 4;
 			break;
+		default:
+			return -1;
 		}
-		CHECK(tis_close());
-		if ((response[6] || response[7] || response[8] || response[9])
-		    && response[9] != 0x26) {
-			/* Ignore postinit errors */
-			printf("tpm command failed at step %d\n"
-			       "tpm error code: %02x%02x%02x%02x\n", i,
-			       response[6], response[7],
-			       response[8], response[9]);
-			rv = -1;
+	}
+
+	return 0;
+}
+
+/**
+ * Read values defined by a type string from a buffer, and write these values
+ * to environment variables.
+ *
+ * @param type_str	type string
+ * @param data		input buffer of values
+ * @param vars		names of environment variables
+ * @return 0 on success, non-0 on error
+ */
+static int type_string_write_vars(const char *type_str, uint8_t *data,
+		char * const vars[])
+{
+	size_t offset;
+	uint32_t value;
+
+	for (offset = 0; *type_str; type_str++, vars++) {
+		switch (*type_str) {
+		case 'b':
+			value = data[offset];
+			offset += 1;
+			break;
+		case 'w':
+			value = get_unaligned_be16(data + offset);
+			offset += 2;
 			break;
+		case 'd':
+			value = get_unaligned_be32(data + offset);
+			offset += 4;
+			break;
+		default:
+			return -1;
 		}
+		if (setenv_ulong(*vars, value))
+			return -1;
 	}
-	return rv;
+
+	return 0;
 }
 
+static int do_tpm_startup(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	enum tpm_startup_type mode;
 
-static int do_tpm_many(cmd_tbl_t *cmdtp, int flag,
-		       int argc, char * const argv[], int repeat_count)
+	if (argc != 2)
+		return CMD_RET_USAGE;
+	if (!strcasecmp("TPM_ST_CLEAR", argv[1])) {
+		mode = TPM_ST_CLEAR;
+	} else if (!strcasecmp("TPM_ST_STATE", argv[1])) {
+		mode = TPM_ST_STATE;
+	} else if (!strcasecmp("TPM_ST_DEACTIVATED", argv[1])) {
+		mode = TPM_ST_DEACTIVATED;
+	} else {
+		printf("Couldn't recognize mode string: %s\n", argv[1]);
+		return CMD_RET_FAILURE;
+	}
+
+	return convert_return_code(tpm_startup(mode));
+}
+
+static int do_tpm_nv_define_space(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t index, perm, size;
+
+	if (argc != 4)
+		return CMD_RET_USAGE;
+	index = simple_strtoul(argv[1], NULL, 0);
+	perm = simple_strtoul(argv[2], NULL, 0);
+	size = simple_strtoul(argv[3], NULL, 0);
+
+	return convert_return_code(tpm_nv_define_space(index, perm, size));
+}
 
+static int do_tpm_nv_read_value(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
 {
-	int rv = 0;
+	uint32_t index, count, rc;
+	void *data;
 
-	if (argc < 7 && repeat_count == 0) {
-		puts("command should be at least six bytes in size\n");
-		return -1;
+	if (argc != 4)
+		return CMD_RET_USAGE;
+	index = simple_strtoul(argv[1], NULL, 0);
+	data = (void *)simple_strtoul(argv[2], NULL, 0);
+	count = simple_strtoul(argv[3], NULL, 0);
+
+	rc = tpm_nv_read_value(index, data, count);
+	if (!rc) {
+		puts("area content:\n");
+		print_byte_string(data, count);
 	}
 
-	if (repeat_count > 0) {
-		rv = tpm_process_stress(repeat_count);
-		return rv;
+	return convert_return_code(rc);
+}
+
+static int do_tpm_nv_write_value(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t index, rc;
+	size_t count;
+	void *data;
+
+	if (argc != 3)
+		return CMD_RET_USAGE;
+	index = simple_strtoul(argv[1], NULL, 0);
+	data = parse_byte_string(argv[2], NULL, &count);
+	if (!data) {
+		printf("Couldn't parse byte string %s\n", argv[2]);
+		return CMD_RET_FAILURE;
 	}
 
-	if (tis_init()) {
-		puts("tis_init() failed!\n");
-		return -1;
+	rc = tpm_nv_write_value(index, data, count);
+	free(data);
+
+	return convert_return_code(rc);
+}
+
+static int do_tpm_extend(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t index, rc;
+	uint8_t in_digest[20], out_digest[20];
+
+	if (argc != 3)
+		return CMD_RET_USAGE;
+	index = simple_strtoul(argv[1], NULL, 0);
+	if (!parse_byte_string(argv[2], in_digest, NULL)) {
+		printf("Couldn't parse byte string %s\n", argv[2]);
+		return CMD_RET_FAILURE;
 	}
 
-	if (tis_open()) {
-		puts("tis_open() failed!\n");
-		return -1;
+	rc = tpm_extend(index, in_digest, out_digest);
+	if (!rc) {
+		puts("PCR value after execution of the command:\n");
+		print_byte_string(out_digest, sizeof(out_digest));
 	}
 
-	rv = tpm_process(argc - 1, argv + 1, cmdtp);
+	return convert_return_code(rc);
+}
+
+static int do_tpm_pcr_read(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t index, count, rc;
+	void *data;
+
+	if (argc != 4)
+		return CMD_RET_USAGE;
+	index = simple_strtoul(argv[1], NULL, 0);
+	data = (void *)simple_strtoul(argv[2], NULL, 0);
+	count = simple_strtoul(argv[3], NULL, 0);
 
-	if (tis_close()) {
-		puts("tis_close() failed!\n");
-		rv = -1;
+	rc = tpm_pcr_read(index, data, count);
+	if (!rc) {
+		puts("Named PCR content:\n");
+		print_byte_string(data, count);
 	}
 
-	return rv;
+	return convert_return_code(rc);
 }
 
+static int do_tpm_tsc_physical_presence(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint16_t presence;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+	presence = (uint16_t)simple_strtoul(argv[1], NULL, 0);
 
-static int do_tpm(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+	return convert_return_code(tpm_tsc_physical_presence(presence));
+}
+
+static int do_tpm_read_pubek(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
 {
-	return do_tpm_many(cmdtp, flag, argc, argv, 0);
+	uint32_t count, rc;
+	void *data;
+
+	if (argc != 3)
+		return CMD_RET_USAGE;
+	data = (void *)simple_strtoul(argv[1], NULL, 0);
+	count = simple_strtoul(argv[2], NULL, 0);
+
+	rc = tpm_read_pubek(data, count);
+	if (!rc) {
+		puts("pubek value:\n");
+		print_byte_string(data, count);
+	}
+
+	return convert_return_code(rc);
 }
 
+static int do_tpm_physical_set_deactivated(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint8_t state;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+	state = (uint8_t)simple_strtoul(argv[1], NULL, 0);
 
-U_BOOT_CMD(tpm, MAX_TRANSACTION_SIZE, 1, do_tpm,
-	   "<byte> [<byte> ...]   - write data and read response",
-	   "send arbitrary data (at least 6 bytes) to the TPM "
-	   "device and read the response"
-);
+	return convert_return_code(tpm_physical_set_deactivated(state));
+}
+
+static int do_tpm_get_capability(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t cap_area, sub_cap, rc;
+	void *cap;
+	size_t count;
+
+	if (argc != 5)
+		return CMD_RET_USAGE;
+	cap_area = simple_strtoul(argv[1], NULL, 0);
+	sub_cap = simple_strtoul(argv[2], NULL, 0);
+	cap = (void *)simple_strtoul(argv[3], NULL, 0);
+	count = simple_strtoul(argv[4], NULL, 0);
+
+	rc = tpm_get_capability(cap_area, sub_cap, cap, count);
+	if (!rc) {
+		puts("capability information:\n");
+		print_byte_string(cap, count);
+	}
+
+	return convert_return_code(rc);
+}
 
-static int do_tpm_stress(cmd_tbl_t *cmdtp, int flag,
-			 int argc, char * const argv[])
+#define TPM_COMMAND_NO_ARG(cmd)				\
+static int do_##cmd(cmd_tbl_t *cmdtp, int flag,		\
+		int argc, char * const argv[])		\
+{							\
+	if (argc != 1)					\
+		return CMD_RET_USAGE;			\
+	return convert_return_code(cmd());		\
+}
+
+TPM_COMMAND_NO_ARG(tpm_init)
+TPM_COMMAND_NO_ARG(tpm_self_test_full)
+TPM_COMMAND_NO_ARG(tpm_continue_self_test)
+TPM_COMMAND_NO_ARG(tpm_force_clear)
+TPM_COMMAND_NO_ARG(tpm_physical_enable)
+TPM_COMMAND_NO_ARG(tpm_physical_disable)
+
+static int do_tpm_raw_transfer(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	void *command;
+	uint8_t response[1024];
+	size_t count, response_length = sizeof(response);
+	uint32_t rc;
+
+	command = parse_byte_string(argv[1], NULL, &count);
+	if (!command) {
+		printf("Couldn't parse byte string %s\n", argv[1]);
+		return CMD_RET_FAILURE;
+	}
+
+	rc = tis_sendrecv(command, count, response, &response_length);
+	free(command);
+	if (!rc) {
+		puts("tpm response:\n");
+		print_byte_string(response, response_length);
+	}
+
+	return convert_return_code(rc);
+}
+
+static int do_tpm_nv_define(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t index, perm, size;
+
+	if (argc != 4)
+		return CMD_RET_USAGE;
+	size = type_string_get_space_size(argv[1]);
+	if (!size) {
+		printf("Couldn't parse arguments\n");
+		return CMD_RET_USAGE;
+	}
+	index = simple_strtoul(argv[2], NULL, 0);
+	perm = simple_strtoul(argv[3], NULL, 0);
+
+	return convert_return_code(tpm_nv_define_space(index, perm, size));
+}
+
+static int do_tpm_nv_read(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
 {
-	long unsigned int n;
-	int rv;
+	uint32_t index, count, err;
+	void *data;
 
-	if (argc != 2) {
-		puts("usage: tpm_stress <count>\n");
-		return -1;
+	if (argc < 3)
+		return CMD_RET_USAGE;
+	if (argc != 3 + type_string_get_num_values(argv[1]))
+		return CMD_RET_USAGE;
+	index = simple_strtoul(argv[2], NULL, 0);
+	data = type_string_alloc(argv[1], &count);
+	if (!data) {
+		printf("Couldn't parse arguments\n");
+		return CMD_RET_USAGE;
 	}
 
-	rv = strict_strtoul(argv[1], 10, &n);
-	if (rv) {
-		puts("tpm_stress: bad count");
-		return -1;
+	err = tpm_nv_read_value(index, data, count);
+	if (!err) {
+		if (type_string_write_vars(argv[1], data, argv + 3)) {
+			printf("Couldn't write to variables\n");
+			err = ~0;
+		}
 	}
+	free(data);
+
+	return convert_return_code(err);
+}
+
+static int do_tpm_nv_write(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t index, count, err;
+	void *data;
+
+	if (argc < 3)
+		return CMD_RET_USAGE;
+	if (argc != 3 + type_string_get_num_values(argv[1]))
+		return CMD_RET_USAGE;
+	index = simple_strtoul(argv[2], NULL, 0);
+	data = type_string_alloc(argv[1], &count);
+	if (!data) {
+		printf("Couldn't parse arguments\n");
+		return CMD_RET_USAGE;
+	}
+	if (type_string_pack(argv[1], argv + 3, data)) {
+		printf("Couldn't parse arguments\n");
+		free(data);
+		return CMD_RET_USAGE;
+	}
+
+	err = tpm_nv_write_value(index, data, count);
+	free(data);
+
+	return convert_return_code(err);
+}
+
+#define MAKE_TPM_CMD_ENTRY(cmd) \
+	U_BOOT_CMD_MKENT(cmd, 0, 1, do_tpm_ ## cmd, "", "")
+
+static cmd_tbl_t tpm_commands[] = {
+	U_BOOT_CMD_MKENT(init, 0, 1,
+			do_tpm_init, "", ""),
+	U_BOOT_CMD_MKENT(startup, 0, 1,
+			do_tpm_startup, "", ""),
+	U_BOOT_CMD_MKENT(self_test_full, 0, 1,
+			do_tpm_self_test_full, "", ""),
+	U_BOOT_CMD_MKENT(continue_self_test, 0, 1,
+			do_tpm_continue_self_test, "", ""),
+	U_BOOT_CMD_MKENT(force_clear, 0, 1,
+			do_tpm_force_clear, "", ""),
+	U_BOOT_CMD_MKENT(physical_enable, 0, 1,
+			do_tpm_physical_enable, "", ""),
+	U_BOOT_CMD_MKENT(physical_disable, 0, 1,
+			do_tpm_physical_disable, "", ""),
+	U_BOOT_CMD_MKENT(nv_define_space, 0, 1,
+			do_tpm_nv_define_space, "", ""),
+	U_BOOT_CMD_MKENT(nv_read_value, 0, 1,
+			do_tpm_nv_read_value, "", ""),
+	U_BOOT_CMD_MKENT(nv_write_value, 0, 1,
+			do_tpm_nv_write_value, "", ""),
+	U_BOOT_CMD_MKENT(extend, 0, 1,
+			do_tpm_extend, "", ""),
+	U_BOOT_CMD_MKENT(pcr_read, 0, 1,
+			do_tpm_pcr_read, "", ""),
+	U_BOOT_CMD_MKENT(tsc_physical_presence, 0, 1,
+			do_tpm_tsc_physical_presence, "", ""),
+	U_BOOT_CMD_MKENT(read_pubek, 0, 1,
+			do_tpm_read_pubek, "", ""),
+	U_BOOT_CMD_MKENT(physical_set_deactivated, 0, 1,
+			do_tpm_physical_set_deactivated, "", ""),
+	U_BOOT_CMD_MKENT(get_capability, 0, 1,
+			do_tpm_get_capability, "", ""),
+	U_BOOT_CMD_MKENT(raw_transfer, 0, 1,
+			do_tpm_raw_transfer, "", ""),
+	U_BOOT_CMD_MKENT(nv_define, 0, 1,
+			do_tpm_nv_define, "", ""),
+	U_BOOT_CMD_MKENT(nv_read, 0, 1,
+			do_tpm_nv_read, "", ""),
+	U_BOOT_CMD_MKENT(nv_write, 0, 1,
+			do_tpm_nv_write, "", ""),
+};
+
+static int do_tpm(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	cmd_tbl_t *tpm_cmd;
+
+	if (argc < 2)
+		return CMD_RET_USAGE;
+	tpm_cmd = find_cmd_tbl(argv[1], tpm_commands, ARRAY_SIZE(tpm_commands));
+	if (!tpm_cmd)
+		return CMD_RET_USAGE;
 
-	return do_tpm_many(cmdtp, flag, argc, argv, n);
+	return tpm_cmd->cmd(cmdtp, flag, argc - 1, argv + 1);
 }
 
-U_BOOT_CMD(tpm_stress, 2, 1, do_tpm_stress,
-	   "<n>   - stress-test communication with TPM",
-	   "Repeat a TPM transaction (request-response) N times"
+U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm,
+"Issue a TPM command",
+"cmd args...\n"
+"    - Issue TPM command <cmd> with arguments <args...>.\n"
+"Admin Startup and State Commands:\n"
+"  init\n"
+"    - Put TPM into a state where it waits for 'startup' command.\n"
+"  startup mode\n"
+"    - Issue TPM_Starup command.  <mode> is one of TPM_ST_CLEAR,\n"
+"      TPM_ST_STATE, and TPM_ST_DEACTIVATED.\n"
+"Admin Testing Commands:\n"
+"  self_test_full\n"
+"    - Test all of the TPM capabilities.\n"
+"  continue_self_test\n"
+"    - Inform TPM that it should complete the self-test.\n"
+"Admin Opt-in Commands:\n"
+"  physical_enable\n"
+"    - Set the PERMANENT disable flag to FALSE using physical presence as\n"
+"      authorization.\n"
+"  physical_disable\n"
+"    - Set the PERMANENT disable flag to TRUE using physical presence as\n"
+"      authorization.\n"
+"  physical_set_deactivated 0|1\n"
+"    - Set deactivated flag.\n"
+"Admin Ownership Commands:\n"
+"  force_clear\n"
+"    - Issue TPM_ForceClear command.\n"
+"  tsc_physical_presence flags\n"
+"    - Set TPM device's Physical Presence flags to <flags>.\n"
+"The Capability Commands:\n"
+"  get_capability cap_area sub_cap addr count\n"
+"    - Read <count> bytes of TPM capability indexed by <cap_area> and\n"
+"      <sub_cap> to memory address <addr>.\n"
+"Endorsement Key Handling Commands:\n"
+"  read_pubek addr count\n"
+"    - Read <count> bytes of the public endorsement key to memory\n"
+"      address <addr>\n"
+"Integrity Collection and Reporting Commands:\n"
+"  extend index digest_hex_string\n"
+"    - Add a new measurement to a PCR.  Update PCR <index> with the 20-bytes\n"
+"      <digest_hex_string>\n"
+"  pcr_read index addr count\n"
+"    - Read <count> bytes from PCR <index> to memory address <addr>.\n"
+"Non-volatile Storage Commands:\n"
+"  nv_define_space index permission size\n"
+"    - Establish a space at index <index> with <permission> of <size> bytes.\n"
+"  nv_read_value index addr count\n"
+"    - Read <count> bytes from space <index> to memory address <addr>.\n"
+"  nv_write_value index addr count\n"
+"    - Write <count> bytes from memory address <addr> to space <index>.\n"
+"Miscellaneous helper functions:\n"
+"  raw_transfer byte_string\n"
+"    - Send a byte string <byte_string> to TPM and print the response.\n"
+" Non-volatile storage helper functions:\n"
+"    These helper functions treat a non-volatile space as a non-padded\n"
+"    sequence of integer values.  These integer values are defined by a type\n"
+"    string, which is a text string of 'bwd' characters: 'b' means a 8-bit\n"
+"    value, 'w' 16-bit value, 'd' 32-bit value.  All helper functions take\n"
+"    a type string as their first argument.\n"
+"  nv_define type_string index perm\n"
+"    - Define a space <index> with permission <perm>.\n"
+"  nv_read types_string index vars...\n"
+"    - Read from space <index> to environment variables <vars...>.\n"
+"  nv_write types_string index values...\n"
+"    - Write to space <index> from values <values...>.\n"
 );
diff --git a/include/tis.h b/include/tis.h
new file mode 100644
index 0000000..89e5730
--- /dev/null
+++ b/include/tis.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef __TIS_H
+#define __TIS_H
+
+#include <common.h>
+
+/* Low-level interface to access TPM */
+
+/*
+ * tis_init()
+ *
+ * Initialize the TPM device. Returns 0 on success or -1 on
+ * failure (in case device probing did not succeed).
+ */
+int tis_init(void);
+
+/*
+ * tis_open()
+ *
+ * Requests access to locality 0 for the caller. After all commands have been
+ * completed the caller is supposed to call tis_close().
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+int tis_open(void);
+
+/*
+ * tis_close()
+ *
+ * terminate the currect session with the TPM by releasing the locked
+ * locality. Returns 0 on success of -1 on failure (in case lock
+ * removal did not succeed).
+ */
+int tis_close(void);
+
+/*
+ * tis_sendrecv()
+ *
+ * Send the requested data to the TPM and then try to get its response
+ *
+ * @sendbuf - buffer of the data to send
+ * @send_size size of the data to send
+ * @recvbuf - memory to save the response to
+ * @recv_len - pointer to the size of the response buffer
+ *
+ * Returns 0 on success (and places the number of response bytes at recv_len)
+ * or -1 on failure.
+ */
+int tis_sendrecv(const uint8_t *sendbuf, size_t send_size, uint8_t *recvbuf,
+			size_t *recv_len);
+
+#endif /* __TIS_H */
diff --git a/include/tpm.h b/include/tpm.h
index 6b21e9c..7219b73 100644
--- a/include/tpm.h
+++ b/include/tpm.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011 The Chromium OS Authors.
+ * Copyright (c) 2013 The Chromium OS Authors.
  *
  * See file CREDITS for list of people who contributed to this
  * project.
@@ -20,52 +20,185 @@
  * MA 02111-1307 USA
  */
 
-#ifndef _INCLUDE_TPM_H_
-#define _INCLUDE_TPM_H_
+#ifndef __TPM_H
+#define __TPM_H
 
-#include <common.h>
+#include <tis.h>
 
 /*
- * tis_init()
+ * Here is a partial implementation of TPM commands.  Please consult TCG Main
+ * Specification for definitions of TPM commands.
+ */
+
+enum tpm_startup_type {
+	TPM_ST_CLEAR		= 0x0001,
+	TPM_ST_STATE		= 0x0002,
+	TPM_ST_DEACTIVATED	= 0x0003,
+};
+
+enum tpm_physical_presence {
+	TPM_PHYSICAL_PRESENCE_HW_DISABLE	= 0x0200,
+	TPM_PHYSICAL_PRESENCE_CMD_DISABLE	= 0x0100,
+	TPM_PHYSICAL_PRESENCE_LIFETIME_LOCK	= 0x0080,
+	TPM_PHYSICAL_PRESENCE_HW_ENABLE		= 0x0040,
+	TPM_PHYSICAL_PRESENCE_CMD_ENABLE	= 0x0020,
+	TPM_PHYSICAL_PRESENCE_NOTPRESENT	= 0x0010,
+	TPM_PHYSICAL_PRESENCE_PRESENT		= 0x0008,
+	TPM_PHYSICAL_PRESENCE_LOCK		= 0x0004,
+};
+
+enum tpm_nv_index {
+	TPM_NV_INDEX_LOCK	= 0xffffffff,
+	TPM_NV_INDEX_0		= 0x00000000,
+	TPM_NV_INDEX_DIR	= 0x10000001,
+};
+
+/**
+ * Initialize TPM device.  It must be called before any TPM commands.
  *
- * Initialize the TPM device. Returns 0 on success or -1 on
- * failure (in case device probing did not succeed).
+ * @return 0 on success, non-0 on error.
  */
-int tis_init(void);
+uint32_t tpm_init(void);
 
-/*
- * tis_open()
+/**
+ * Issue a TPM_Startup command.
  *
- * Requests access to locality 0 for the caller. After all commands have been
- * completed the caller is supposed to call tis_close().
+ * @param mode		TPM startup mode
+ * @return return code of the operation
+ */
+uint32_t tpm_startup(enum tpm_startup_type mode);
+
+/**
+ * Issue a TPM_SelfTestFull command.
  *
- * Returns 0 on success, -1 on failure.
+ * @return return code of the operation
  */
-int tis_open(void);
+uint32_t tpm_self_test_full(void);
 
-/*
- * tis_close()
+/**
+ * Issue a TPM_ContinueSelfTest command.
  *
- * terminate the currect session with the TPM by releasing the locked
- * locality. Returns 0 on success of -1 on failure (in case lock
- * removal did not succeed).
+ * @return return code of the operation
  */
-int tis_close(void);
+uint32_t tpm_continue_self_test(void);
 
-/*
- * tis_sendrecv()
+/**
+ * Issue a TPM_NV_DefineSpace command.  The implementation is limited
+ * to specify TPM_NV_ATTRIBUTES and size of the area.  The area index
+ * could be one of the special value listed in enum tpm_nv_index.
  *
- * Send the requested data to the TPM and then try to get its response
+ * @param index		index of the area
+ * @param perm		TPM_NV_ATTRIBUTES of the area
+ * @param size		size of the area
+ * @return return code of the operation
+ */
+uint32_t tpm_nv_define_space(uint32_t index, uint32_t perm, uint32_t size);
+
+/**
+ * Issue a TPM_NV_ReadValue command.  This implementation is limited
+ * to read the area from offset 0.  The area index could be one of
+ * the special value listed in enum tpm_nv_index.
+ *
+ * @param index		index of the area
+ * @param data		output buffer of the area contents
+ * @param count		size of output buffer
+ * @return return code of the operation
+ */
+uint32_t tpm_nv_read_value(uint32_t index, void *data, uint32_t count);
+
+/**
+ * Issue a TPM_NV_WriteValue command.  This implementation is limited
+ * to write the area from offset 0.  The area index could be one of
+ * the special value listed in enum tpm_nv_index.
+ *
+ * @param index		index of the area
+ * @param data		input buffer to be wrote to the area
+ * @param length	length of data bytes of input buffer
+ * @return return code of the operation
+ */
+uint32_t tpm_nv_write_value(uint32_t index, const void *data, uint32_t length);
+
+/**
+ * Issue a TPM_Extend command.
+ *
+ * @param index		index of the PCR
+ * @param in_digest	160-bit value representing the event to be
+ *			recorded
+ * @param out_digest	160-bit PCR value after execution of the
+ *			command
+ * @return return code of the operation
+ */
+uint32_t tpm_extend(uint32_t index, const void *in_digest, void *out_digest);
+
+/**
+ * Issue a TPM_PCRRead command.
  *
- * @sendbuf - buffer of the data to send
- * @send_size size of the data to send
- * @recvbuf - memory to save the response to
- * @recv_len - pointer to the size of the response buffer
+ * @param index		index of the PCR
+ * @param data		output buffer for contents of the named PCR
+ * @param count		size of output buffer
+ * @return return code of the operation
+ */
+uint32_t tpm_pcr_read(uint32_t index, void *data, size_t count);
+
+/**
+ * Issue a TSC_PhysicalPresence command.  TPM physical presence flag
+ * is bit-wise OR'ed of flags listed in enum tpm_physical_presence.
+ *
+ * @param presence	TPM physical presence flag
+ * @return return code of the operation
+ */
+uint32_t tpm_tsc_physical_presence(uint16_t presence);
+
+/**
+ * Issue a TPM_ReadPubek command.
+ *
+ * @param data		output buffer for the public endorsement key
+ * @param count		size of ouput buffer
+ * @return return code of the operation
+ */
+uint32_t tpm_read_pubek(void *data, size_t count);
+
+/**
+ * Issue a TPM_ForceClear command.
+ *
+ * @return return code of the operation
+ */
+uint32_t tpm_force_clear(void);
+
+/**
+ * Issue a TPM_PhysicalEnable command.
+ *
+ * @return return code of the operation
+ */
+uint32_t tpm_physical_enable(void);
+
+/**
+ * Issue a TPM_PhysicalDisable command.
+ *
+ * @return return code of the operation
+ */
+uint32_t tpm_physical_disable(void);
+
+/**
+ * Issue a TPM_PhysicalSetDeactivated command.
+ *
+ * @param state		boolean state of the deactivated flag
+ * @return return code of the operation
+ */
+uint32_t tpm_physical_set_deactivated(uint8_t state);
+
+/**
+ * Issue a TPM_GetCapability command.  This implementation is limited
+ * to query sub_cap index that is 4-byte wide.
  *
- * Returns 0 on success (and places the number of response bytes at recv_len)
- * or -1 on failure.
+ * @param cap_area	partition of capabilities
+ * @param sub_cap	further definition of capability, which is
+ *			limited to be 4-byte wide
+ * @param cap		output buffer for capability information
+ * @param count		size of ouput buffer
+ * @return return code of the operation
  */
-int tis_sendrecv(const uint8_t *sendbuf, size_t send_size, uint8_t *recvbuf,
-			size_t *recv_len);
+uint32_t tpm_get_capability(uint32_t cap_area, uint32_t sub_cap,
+		void *cap, size_t count);
 
-#endif /* _INCLUDE_TPM_H_ */
+#endif /* __TPM_H */
diff --git a/lib/Makefile b/lib/Makefile
index 1bfd3ee..d57775d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -54,6 +54,7 @@ COBJS-y += qsort.o
 COBJS-$(CONFIG_SHA1) += sha1.o
 COBJS-$(CONFIG_SHA256) += sha256.o
 COBJS-y	+= strmhz.o
+COBJS-$(CONFIG_TPM) += tpm.o
 COBJS-$(CONFIG_RBTREE)	+= rbtree.o
 endif
 
diff --git a/lib/tpm.c b/lib/tpm.c
new file mode 100644
index 0000000..42c9bea
--- /dev/null
+++ b/lib/tpm.c
@@ -0,0 +1,581 @@
+/*
+ * Copyright (c) 2013 The Chromium OS Authors.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <stdarg.h>
+#include <tpm.h>
+#include <asm/unaligned.h>
+
+/* Internal error of TPM command library */
+#define TPM_LIB_ERROR	((uint32_t)~0u)
+
+/* Useful constants */
+enum {
+	COMMAND_BUFFER_SIZE		= 256,
+	TPM_PUBEK_SIZE			= 256,
+	TPM_REQUEST_HEADER_LENGTH	= 10,
+	TPM_RESPONSE_HEADER_LENGTH	= 10,
+	PCR_DIGEST_LENGTH		= 20,
+};
+
+/**
+ * Pack data into a byte string.  The data types are specified in
+ * the format string: 'b' means unsigned byte, 'w' unsigned word,
+ * 'd' unsigned double word, and 's' byte string.  The data are a
+ * series of offsets and values (for type byte string there are also
+ * lengths).  The data values are packed into the byte string
+ * sequentially, and so a latter value could over-write a former
+ * value.
+ *
+ * @param str		output string
+ * @param size		size of output string
+ * @param format	format string
+ * @param ...		data points
+ * @return 0 on success, non-0 on error
+ */
+int pack_byte_string(uint8_t *str, size_t size, const char *format, ...)
+{
+	va_list args;
+	size_t offset = 0, length = 0;
+	uint8_t *data = NULL;
+	uint32_t value = 0;
+
+	va_start(args, format);
+	for (; *format; format++) {
+		switch (*format) {
+		case 'b':
+			offset = va_arg(args, size_t);
+			value = va_arg(args, int);
+			length = 1;
+			break;
+		case 'w':
+			offset = va_arg(args, size_t);
+			value = va_arg(args, int);
+			length = 2;
+			break;
+		case 'd':
+			offset = va_arg(args, size_t);
+			value = va_arg(args, uint32_t);
+			length = 4;
+			break;
+		case 's':
+			offset = va_arg(args, size_t);
+			data = va_arg(args, uint8_t *);
+			length = va_arg(args, uint32_t);
+			break;
+		default:
+			debug("Couldn't recognize format string\n");
+			return -1;
+		}
+
+		if (offset + length > size)
+			return -1;
+
+		switch (*format) {
+		case 'b':
+			str[offset] = value;
+			break;
+		case 'w':
+			put_unaligned_be16(value, str + offset);
+			break;
+		case 'd':
+			put_unaligned_be32(value, str + offset);
+			break;
+		case 's':
+			memcpy(str + offset, data, length);
+			break;
+		}
+	}
+	va_end(args);
+
+	return 0;
+}
+
+/**
+ * Unpack data from a byte string.  The data types are specified in
+ * the format string: 'b' means unsigned byte, 'w' unsigned word,
+ * 'd' unsigned double word, and 's' byte string.  The data are a
+ * series of offsets and pointers (for type byte string there are also
+ * lengths).
+ *
+ * @param str		output string
+ * @param size		size of output string
+ * @param format	format string
+ * @param ...		data points
+ * @return 0 on success, non-0 on error
+ */
+int unpack_byte_string(const uint8_t *str, size_t size, const char *format, ...)
+{
+	va_list args;
+	size_t offset = 0, length = 0;
+	uint8_t *ptr8 = NULL;
+	uint16_t *ptr16 = NULL;
+	uint32_t *ptr32 = NULL;
+
+	va_start(args, format);
+	for (; *format; format++) {
+		switch (*format) {
+		case 'b':
+			offset = va_arg(args, size_t);
+			ptr8 = va_arg(args, uint8_t *);
+			length = 1;
+			break;
+		case 'w':
+			offset = va_arg(args, size_t);
+			ptr16 = va_arg(args, uint16_t *);
+			length = 2;
+			break;
+		case 'd':
+			offset = va_arg(args, size_t);
+			ptr32 = va_arg(args, uint32_t *);
+			length = 4;
+			break;
+		case 's':
+			offset = va_arg(args, size_t);
+			ptr8 = va_arg(args, uint8_t *);
+			length = va_arg(args, uint32_t);
+			break;
+		default:
+			debug("Couldn't recognize format string\n");
+			return -1;
+		}
+
+		if (offset + length > size)
+			return -1;
+
+		switch (*format) {
+		case 'b':
+			*ptr8 = str[offset];
+			break;
+		case 'w':
+			*ptr16 = get_unaligned_be16(str + offset);
+			break;
+		case 'd':
+			*ptr32 = get_unaligned_be32(str + offset);
+			break;
+		case 's':
+			memcpy(ptr8, str + offset, length);
+			break;
+		}
+	}
+	va_end(args);
+
+	return 0;
+}
+
+/**
+ * Get TPM command size.
+ *
+ * @param command	byte string of TPM command
+ * @return command size of the TPM command
+ */
+static uint32_t tpm_command_size(const void *command)
+{
+	const size_t command_size_offset = 2;
+	return get_unaligned_be32(command + command_size_offset);
+}
+
+/**
+ * Get TPM response return code, which is one of TPM_RESULT values.
+ *
+ * @param response	byte string of TPM response
+ * @return return code of the TPM response
+ */
+static uint32_t tpm_return_code(const void *response)
+{
+	const size_t return_code_offset = 6;
+	return get_unaligned_be32(response + return_code_offset);
+}
+
+/**
+ * Send a TPM command and return response's return code, and optionally
+ * return response to caller.
+ *
+ * @param command	byte string of TPM command
+ * @param response	output buffer for TPM response, or NULL if the
+ *			caller does not care about it
+ * @param size_ptr	output buffer size (input parameter) and TPM
+ *			response length (output parameter); this parameter
+ *			is a bidirectional
+ * @return return code of the TPM response
+ */
+static uint32_t tpm_sendrecv_command(const void *command,
+		void *response, size_t *size_ptr)
+{
+	uint8_t response_buffer[COMMAND_BUFFER_SIZE];
+	size_t response_length;
+	uint32_t err;
+
+	if (response) {
+		response_length = *size_ptr;
+	} else {
+		response = response_buffer;
+		response_length = sizeof(response_buffer);
+	}
+	err = tis_sendrecv(command, tpm_command_size(command),
+			response, &response_length);
+	if (err)
+		return TPM_LIB_ERROR;
+	if (response)
+		*size_ptr = response_length;
+
+	return tpm_return_code(response);
+}
+
+uint32_t tpm_init(void)
+{
+	uint32_t err;
+
+	err = tis_init();
+	if (err)
+		return err;
+
+	return tis_open();
+}
+
+uint32_t tpm_startup(enum tpm_startup_type mode)
+{
+	const uint8_t command[12] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xc, 0x0, 0x0, 0x0, 0x99, 0x0, 0x0,
+	};
+	const size_t mode_offset = 10;
+	uint8_t buf[COMMAND_BUFFER_SIZE];
+
+	if (pack_byte_string(buf, sizeof(buf), "sw",
+				0, command, sizeof(command),
+				mode_offset, mode))
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(buf, NULL, NULL);
+}
+
+uint32_t tpm_self_test_full(void)
+{
+	const uint8_t command[10] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xa, 0x0, 0x0, 0x0, 0x50,
+	};
+	return tpm_sendrecv_command(command, NULL, NULL);
+}
+
+uint32_t tpm_continue_self_test(void)
+{
+	const uint8_t command[10] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xa, 0x0, 0x0, 0x0, 0x53,
+	};
+	return tpm_sendrecv_command(command, NULL, NULL);
+}
+
+uint32_t tpm_nv_define_space(uint32_t index, uint32_t perm, uint32_t size)
+{
+	const uint8_t command[101] = {
+		0x0, 0xc1,		/* TPM_TAG */
+		0x0, 0x0, 0x0, 0x65,	/* parameter size */
+		0x0, 0x0, 0x0, 0xcc,	/* TPM_COMMAND_CODE */
+		/* TPM_NV_DATA_PUBLIC->... */
+		0x0, 0x18,		/* ...->TPM_STRUCTURE_TAG */
+		0, 0, 0, 0,		/* ...->TPM_NV_INDEX */
+		/* TPM_NV_DATA_PUBLIC->TPM_PCR_INFO_SHORT */
+		0x0, 0x3,
+		0, 0, 0,
+		0x1f,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		/* TPM_NV_DATA_PUBLIC->TPM_PCR_INFO_SHORT */
+		0x0, 0x3,
+		0, 0, 0,
+		0x1f,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		/* TPM_NV_ATTRIBUTES->... */
+		0x0, 0x17,		/* ...->TPM_STRUCTURE_TAG */
+		0, 0, 0, 0,		/* ...->attributes */
+		/* End of TPM_NV_ATTRIBUTES */
+		0,			/* bReadSTClear */
+		0,			/* bWriteSTClear */
+		0,			/* bWriteDefine */
+		0, 0, 0, 0,		/* size */
+	};
+	const size_t index_offset = 12;
+	const size_t perm_offset = 70;
+	const size_t size_offset = 77;
+	uint8_t buf[COMMAND_BUFFER_SIZE];
+
+	if (pack_byte_string(buf, sizeof(buf), "sddd",
+				0, command, sizeof(command),
+				index_offset, index,
+				perm_offset, perm,
+				size_offset, size))
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(buf, NULL, NULL);
+}
+
+uint32_t tpm_nv_read_value(uint32_t index, void *data, uint32_t count)
+{
+	const uint8_t command[22] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0x16, 0x0, 0x0, 0x0, 0xcf,
+	};
+	const size_t index_offset = 10;
+	const size_t length_offset = 18;
+	const size_t data_size_offset = 10;
+	const size_t data_offset = 14;
+	uint8_t buf[COMMAND_BUFFER_SIZE], response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t data_size;
+	uint32_t err;
+
+	if (pack_byte_string(buf, sizeof(buf), "sdd",
+				0, command, sizeof(command),
+				index_offset, index,
+				length_offset, count))
+		return TPM_LIB_ERROR;
+	err = tpm_sendrecv_command(buf, response, &response_length);
+	if (err)
+		return err;
+	if (unpack_byte_string(response, response_length, "d",
+				data_size_offset, &data_size))
+		return TPM_LIB_ERROR;
+	if (data_size > count)
+		return TPM_LIB_ERROR;
+	if (unpack_byte_string(response, response_length, "s",
+				data_offset, data, data_size))
+		return TPM_LIB_ERROR;
+
+	return 0;
+}
+
+uint32_t tpm_nv_write_value(uint32_t index, const void *data, uint32_t length)
+{
+	const uint8_t command[256] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xcd,
+	};
+	const size_t command_size_offset = 2;
+	const size_t index_offset = 10;
+	const size_t length_offset = 18;
+	const size_t data_offset = 22;
+	const size_t write_info_size = 12;
+	const uint32_t total_length =
+		TPM_REQUEST_HEADER_LENGTH + write_info_size + length;
+	uint8_t buf[COMMAND_BUFFER_SIZE], response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (pack_byte_string(buf, sizeof(buf), "sddds",
+				0, command, sizeof(command),
+				command_size_offset, total_length,
+				index_offset, index,
+				length_offset, length,
+				data_offset, data, length))
+		return TPM_LIB_ERROR;
+	err = tpm_sendrecv_command(buf, response, &response_length);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+uint32_t tpm_extend(uint32_t index, const void *in_digest, void *out_digest)
+{
+	const uint8_t command[34] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0x22, 0x0, 0x0, 0x0, 0x14,
+	};
+	const size_t index_offset = 10;
+	const size_t in_digest_offset = 14;
+	const size_t out_digest_offset = 10;
+	uint8_t buf[COMMAND_BUFFER_SIZE];
+	uint8_t response[TPM_RESPONSE_HEADER_LENGTH + PCR_DIGEST_LENGTH];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (pack_byte_string(buf, sizeof(buf), "sds",
+				0, command, sizeof(command),
+				index_offset, index,
+				in_digest_offset, in_digest,
+				PCR_DIGEST_LENGTH))
+		return TPM_LIB_ERROR;
+	err = tpm_sendrecv_command(buf, response, &response_length);
+	if (err)
+		return err;
+
+	if (unpack_byte_string(response, response_length, "s",
+				out_digest_offset, out_digest,
+				PCR_DIGEST_LENGTH))
+		return TPM_LIB_ERROR;
+
+	return 0;
+}
+
+uint32_t tpm_pcr_read(uint32_t index, void *data, size_t count)
+{
+	const uint8_t command[14] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xe, 0x0, 0x0, 0x0, 0x15,
+	};
+	const size_t index_offset = 10;
+	const size_t out_digest_offset = 10;
+	uint8_t buf[COMMAND_BUFFER_SIZE], response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (count < PCR_DIGEST_LENGTH)
+		return TPM_LIB_ERROR;
+
+	if (pack_byte_string(buf, sizeof(buf), "sd",
+				0, command, sizeof(command),
+				index_offset, index))
+		return TPM_LIB_ERROR;
+	err = tpm_sendrecv_command(buf, response, &response_length);
+	if (err)
+		return err;
+	if (unpack_byte_string(response, response_length, "s",
+				out_digest_offset, data, PCR_DIGEST_LENGTH))
+		return TPM_LIB_ERROR;
+
+	return 0;
+}
+
+uint32_t tpm_tsc_physical_presence(uint16_t presence)
+{
+	const uint8_t command[12] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xc, 0x40, 0x0, 0x0, 0xa, 0x0, 0x0,
+	};
+	const size_t presence_offset = 10;
+	uint8_t buf[COMMAND_BUFFER_SIZE];
+
+	if (pack_byte_string(buf, sizeof(buf), "sw",
+				0, command, sizeof(command),
+				presence_offset, presence))
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(buf, NULL, NULL);
+}
+
+uint32_t tpm_read_pubek(void *data, size_t count)
+{
+	const uint8_t command[30] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0x1e, 0x0, 0x0, 0x0, 0x7c,
+	};
+	const size_t response_size_offset = 2;
+	const size_t data_offset = 10;
+	const size_t header_and_checksum_size = TPM_RESPONSE_HEADER_LENGTH + 20;
+	uint8_t response[COMMAND_BUFFER_SIZE + TPM_PUBEK_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t data_size;
+	uint32_t err;
+
+	err = tpm_sendrecv_command(command, response, &response_length);
+	if (err)
+		return err;
+	if (unpack_byte_string(response, response_length, "d",
+				response_size_offset, &data_size))
+		return TPM_LIB_ERROR;
+	if (data_size < header_and_checksum_size)
+		return TPM_LIB_ERROR;
+	data_size -= header_and_checksum_size;
+	if (data_size > count)
+		return TPM_LIB_ERROR;
+	if (unpack_byte_string(response, response_length, "s",
+				data_offset, data, data_size))
+		return TPM_LIB_ERROR;
+
+	return 0;
+}
+
+uint32_t tpm_force_clear(void)
+{
+	const uint8_t command[10] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xa, 0x0, 0x0, 0x0, 0x5d,
+	};
+
+	return tpm_sendrecv_command(command, NULL, NULL);
+}
+
+uint32_t tpm_physical_enable(void)
+{
+	const uint8_t command[10] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xa, 0x0, 0x0, 0x0, 0x6f,
+	};
+
+	return tpm_sendrecv_command(command, NULL, NULL);
+}
+
+uint32_t tpm_physical_disable(void)
+{
+	const uint8_t command[10] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xa, 0x0, 0x0, 0x0, 0x70,
+	};
+
+	return tpm_sendrecv_command(command, NULL, NULL);
+}
+
+uint32_t tpm_physical_set_deactivated(uint8_t state)
+{
+	const uint8_t command[11] = {
+		0x0, 0xc1, 0x0, 0x0, 0x0, 0xb, 0x0, 0x0, 0x0, 0x72,
+	};
+	const size_t state_offset = 10;
+	uint8_t buf[COMMAND_BUFFER_SIZE];
+
+	if (pack_byte_string(buf, sizeof(buf), "sb",
+				0, command, sizeof(command),
+				state_offset, state))
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(buf, NULL, NULL);
+}
+
+uint32_t tpm_get_capability(uint32_t cap_area, uint32_t sub_cap,
+		void *cap, size_t count)
+{
+	const uint8_t command[22] = {
+		0x0, 0xc1,		/* TPM_TAG */
+		0x0, 0x0, 0x0, 0x16,	/* parameter size */
+		0x0, 0x0, 0x0, 0x65,	/* TPM_COMMAND_CODE */
+		0x0, 0x0, 0x0, 0x0,	/* TPM_CAPABILITY_AREA */
+		0x0, 0x0, 0x0, 0x4,	/* subcap size */
+		0x0, 0x0, 0x0, 0x0,	/* subcap value */
+	};
+	const size_t cap_area_offset = 10;
+	const size_t sub_cap_offset = 18;
+	const size_t cap_offset = 14;
+	const size_t cap_size_offset = 10;
+	uint8_t buf[COMMAND_BUFFER_SIZE], response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t cap_size;
+	uint32_t err;
+
+	if (pack_byte_string(buf, sizeof(buf), "sdd",
+				0, command, sizeof(command),
+				cap_area_offset, cap_area,
+				sub_cap_offset, sub_cap))
+		return TPM_LIB_ERROR;
+	err = tpm_sendrecv_command(buf, response, &response_length);
+	if (err)
+		return err;
+	if (unpack_byte_string(response, response_length, "d",
+				cap_size_offset, &cap_size))
+		return TPM_LIB_ERROR;
+	if (cap_size > response_length || cap_size > count)
+		return TPM_LIB_ERROR;
+	if (unpack_byte_string(response, response_length, "s",
+				cap_offset, cap, cap_size))
+		return TPM_LIB_ERROR;
+
+	return 0;
+}