diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f8319a0..205e7c2 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -382,6 +382,93 @@ struct tpm_cmd_t {
 	tpm_cmd_params	params;
 } __packed;
 
+/* A string buffer type for constructing TPM commands. This is based on the
+ * code in security/keys/trusted.h.
+ */
+
+#define TPM_BUF_SIZE 512
+
+struct tpm_buf {
+	u8 data[TPM_BUF_SIZE];
+} __attribute__((aligned(8)));
+
+static inline void tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
+{
+	struct tpm_input_header *head = (struct tpm_input_header *) buf->data;
+
+	head->tag = cpu_to_be16(tag);
+	head->length = cpu_to_be32(sizeof(*head));
+	head->ordinal = cpu_to_be32(ordinal);
+}
+
+static inline u32 tpm_buf_length(struct tpm_buf *buf)
+{
+	struct tpm_input_header *head = (struct tpm_input_header *) buf->data;
+
+	return be32_to_cpu(head->length);
+}
+
+static inline u16 tpm_buf_tag(struct tpm_buf *buf)
+{
+	struct tpm_input_header *head = (struct tpm_input_header *) buf->data;
+
+	return be16_to_cpu(head->tag);
+}
+
+static inline u8 *tpm_buf_out(struct tpm_buf *buf)
+{
+	return &buf->data[TPM_HEADER_SIZE];
+}
+
+static inline void tpm_buf_append(struct tpm_buf *buf,
+				  const unsigned char *data,
+				  unsigned int len)
+{
+	struct tpm_input_header *head = (struct tpm_input_header *) buf->data;
+
+	BUG_ON((len + tpm_buf_length(buf)) > TPM_BUF_SIZE);
+
+	memcpy(&buf->data[tpm_buf_length(buf)], data, len);
+	head->length = cpu_to_be32(tpm_buf_length(buf) + len);
+}
+
+static inline void tpm_buf_store(struct tpm_buf *buf,
+				 unsigned int pos,
+				 const unsigned char *data,
+				 unsigned int len)
+{
+	BUG_ON((pos + len) > TPM_BUF_SIZE);
+
+	memcpy(&buf->data[pos], data, len);
+}
+
+static inline void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value)
+{
+	tpm_buf_append(buf, &value, 1);
+}
+
+static inline void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value)
+{
+	__be16 value2 = cpu_to_be16(value);
+
+	tpm_buf_append(buf, (u8 *) &value2, 2);
+}
+
+static inline void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
+{
+	__be32 value2 = cpu_to_be32(value);
+
+	tpm_buf_append(buf, (u8 *) &value2, 4);
+}
+
+static inline void tpm_buf_store_u32(struct tpm_buf *buf, unsigned int pos,
+				     const u32 value)
+{
+	__be32 value2 = cpu_to_be32(value);
+
+	tpm_buf_store(buf, pos, (u8 *) &value2, 4);
+}
+
 extern struct class *tpm_class;
 extern dev_t tpm_devt;
 extern const struct file_operations tpm_fops;
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 011909a..a274cef 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -17,14 +17,6 @@
 
 #include "tpm.h"
 
-struct tpm2_startup_in {
-	__be16	startup_type;
-} __packed;
-
-struct tpm2_self_test_in {
-	u8	full_test;
-} __packed;
-
 struct tpm2_pcr_read_in {
 	__be32	pcr_selects_cnt;
 	__be16	hash_alg;
@@ -43,17 +35,7 @@ struct tpm2_pcr_read_out {
 	u8	digest[TPM_DIGEST_SIZE];
 } __packed;
 
-struct tpm2_null_auth_area {
-	__be32			handle;
-	__be16			nonce_size;
-	u8			attributes;
-	__be16			auth_size;
-} __packed;
-
 struct tpm2_pcr_extend_in {
-	__be32				pcr_idx;
-	__be32				auth_area_size;
-	struct tpm2_null_auth_area	auth_area;
 	__be32				digest_cnt;
 	__be16				hash_alg;
 	u8				digest[TPM_DIGEST_SIZE];
@@ -73,32 +55,11 @@ struct tpm2_get_tpm_pt_out {
 	__be32	value;
 } __packed;
 
-struct tpm2_get_random_in {
-	__be16	size;
-} __packed;
-
 struct tpm2_get_random_out {
 	__be16	size;
 	u8	buffer[TPM_MAX_RNG_DATA];
 } __packed;
 
-union tpm2_cmd_params {
-	struct	tpm2_startup_in		startup_in;
-	struct	tpm2_self_test_in	selftest_in;
-	struct	tpm2_pcr_read_in	pcrread_in;
-	struct	tpm2_pcr_read_out	pcrread_out;
-	struct	tpm2_pcr_extend_in	pcrextend_in;
-	struct	tpm2_get_tpm_pt_in	get_tpm_pt_in;
-	struct	tpm2_get_tpm_pt_out	get_tpm_pt_out;
-	struct	tpm2_get_random_in	getrandom_in;
-	struct	tpm2_get_random_out	getrandom_out;
-};
-
-struct tpm2_cmd {
-	tpm_cmd_header		header;
-	union tpm2_cmd_params	params;
-} __packed;
-
 /*
  * Array with one entry per ordinal defining the maximum amount
  * of time the chip could take to return the result. The values
@@ -221,15 +182,28 @@ static const u8 tpm2_ordinal_duration[TPM2_CC_LAST - TPM2_CC_FIRST + 1] = {
 	TPM_UNDEFINED		/* 18f */
 };
 
-#define TPM2_PCR_READ_IN_SIZE \
-	(sizeof(struct tpm_input_header) + \
-	 sizeof(struct tpm2_pcr_read_in))
+static void tpm2_buf_append_auth(struct tpm_buf *buf, u32 session_handle,
+				 const u8 *nonce, u16 nonce_len,
+				 u8 session_attributes,
+				 const u8 *hmac, u16 hmac_len)
+{
+	u32 buf_len = tpm_buf_length(buf);
+
+	tpm_buf_append_u32(buf, 0);
+	tpm_buf_append_u32(buf, session_handle);
+	tpm_buf_append_u16(buf, nonce_len);
 
-static const struct tpm_input_header tpm2_pcrread_header = {
-	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
-	.length = cpu_to_be32(TPM2_PCR_READ_IN_SIZE),
-	.ordinal = cpu_to_be32(TPM2_CC_PCR_READ)
-};
+	if (nonce)
+		tpm_buf_append(buf, nonce, nonce_len);
+
+	tpm_buf_append_u8(buf, session_attributes);
+	tpm_buf_append_u16(buf, hmac_len);
+
+	if (hmac)
+		tpm_buf_append(buf, hmac, hmac_len);
+
+	tpm_buf_store_u32(buf, buf_len, tpm_buf_length(buf) - buf_len);
+}
 
 /**
  * tpm2_pcr_read() - read a PCR value
@@ -243,42 +217,36 @@ static const struct tpm_input_header tpm2_pcrread_header = {
  */
 int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 {
+	struct tpm_buf buf;
+	struct tpm2_pcr_read_in in;
+	struct tpm2_pcr_read_out *out;
 	int rc;
-	struct tpm2_cmd cmd;
-	u8 *buf;
 
 	if (pcr_idx >= TPM2_PLATFORM_PCR)
 		return -EINVAL;
 
-	cmd.header.in = tpm2_pcrread_header;
-	cmd.params.pcrread_in.pcr_selects_cnt = cpu_to_be32(1);
-	cmd.params.pcrread_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
-	cmd.params.pcrread_in.pcr_select_size = TPM2_PCR_SELECT_MIN;
+	tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
 
-	memset(cmd.params.pcrread_in.pcr_select, 0,
-	       sizeof(cmd.params.pcrread_in.pcr_select));
-	cmd.params.pcrread_in.pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);
+	in.pcr_selects_cnt = cpu_to_be32(1);
+	in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
+	in.pcr_select_size = TPM2_PCR_SELECT_MIN;
+	in.pcr_select[0] = 0x00;
+	in.pcr_select[1] = 0x00;
+	in.pcr_select[2] = 0x00;
+	in.pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
+	tpm_buf_append(&buf, (u8 *) &in, sizeof(in));
+
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE,
 			      "attempting to read a pcr value");
-	if (rc == 0) {
-		buf = cmd.params.pcrread_out.digest;
-		memcpy(res_buf, buf, TPM_DIGEST_SIZE);
-	}
+	if (rc)
+		return rc;
 
-	return rc;
+	out = (struct tpm2_pcr_read_out *) &buf.data[TPM_HEADER_SIZE];
+	memcpy(res_buf, out->digest, TPM_DIGEST_SIZE);
+	return 0;
 }
 
-#define TPM2_GET_PCREXTEND_IN_SIZE \
-	(sizeof(struct tpm_input_header) + \
-	 sizeof(struct tpm2_pcr_extend_in))
-
-static const struct tpm_input_header tpm2_pcrextend_header = {
-	.tag = cpu_to_be16(TPM2_ST_SESSIONS),
-	.length = cpu_to_be32(TPM2_GET_PCREXTEND_IN_SIZE),
-	.ordinal = cpu_to_be32(TPM2_CC_PCR_EXTEND)
-};
-
 /**
  * tpm2_pcr_extend() - extend a PCR value
  * @chip:	TPM chip to use.
@@ -291,76 +259,63 @@ static const struct tpm_input_header tpm2_pcrextend_header = {
  */
 int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
 {
-	struct tpm2_cmd cmd;
-	int rc;
-
-	cmd.header.in = tpm2_pcrextend_header;
-	cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
-	cmd.params.pcrextend_in.auth_area_size =
-		cpu_to_be32(sizeof(struct tpm2_null_auth_area));
-	cmd.params.pcrextend_in.auth_area.handle =
-		cpu_to_be32(TPM2_RS_PW);
-	cmd.params.pcrextend_in.auth_area.nonce_size = 0;
-	cmd.params.pcrextend_in.auth_area.attributes = 0;
-	cmd.params.pcrextend_in.auth_area.auth_size = 0;
-	cmd.params.pcrextend_in.digest_cnt = cpu_to_be32(1);
-	cmd.params.pcrextend_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
-	memcpy(cmd.params.pcrextend_in.digest, hash, TPM_DIGEST_SIZE);
-
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
-			      "attempting extend a PCR value");
+	struct tpm_buf buf;
+	struct tpm2_pcr_extend_in in;
 
-	return rc;
-}
+	tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
+	tpm_buf_append_u32(&buf, pcr_idx);
+	tpm2_buf_append_auth(&buf, TPM2_RS_PW, NULL /* nonce */, 0,
+			     0 /* session_attributes */, NULL /* hmac */, 0);
 
-#define TPM2_GETRANDOM_IN_SIZE \
-	(sizeof(struct tpm_input_header) + \
-	 sizeof(struct tpm2_get_random_in))
+	in.digest_cnt = cpu_to_be32(1);
+	in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
+	memcpy(in.digest, hash, TPM_DIGEST_SIZE);
+	tpm_buf_append(&buf, (u8 *) &in, sizeof(in));
 
-static const struct tpm_input_header tpm2_getrandom_header = {
-	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
-	.length = cpu_to_be32(TPM2_GETRANDOM_IN_SIZE),
-	.ordinal = cpu_to_be32(TPM2_CC_GET_RANDOM)
-};
+	return tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE,
+				"attempting extend a PCR value");
+}
 
 /**
  * tpm2_get_random() - get random bytes from the TPM RNG
  * @chip: TPM chip to use
- * @out: destination buffer for the random bytes
+ * @res_buf: destination buffer for the random bytes
  * @max: the max number of bytes to write to @out
  *
  * 0 is returned when the operation is successful. If a negative number is
  * returned it remarks a POSIX error code. If a positive number is returned
  * it remarks a TPM error.
  */
-int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max)
+int tpm2_get_random(struct tpm_chip *chip, u8 *res_buf, size_t max)
 {
-	struct tpm2_cmd cmd;
+	struct tpm_buf buf;
+	struct tpm2_get_random_out *out;
 	u32 recd;
 	u32 num_bytes;
 	int err;
 	int total = 0;
 	int retries = 5;
-	u8 *dest = out;
+	u8 *dest = res_buf;
 
-	num_bytes = min_t(u32, max, sizeof(cmd.params.getrandom_out.buffer));
+	num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA);
 
-	if (!out || !num_bytes ||
-	    max > sizeof(cmd.params.getrandom_out.buffer))
+	if (!res_buf || !num_bytes || max > TPM_MAX_RNG_DATA)
 		return -EINVAL;
 
 	do {
-		cmd.header.in = tpm2_getrandom_header;
-		cmd.params.getrandom_in.size = cpu_to_be16(num_bytes);
 
-		err = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
+		tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
+		tpm_buf_append_u16(&buf, num_bytes);
+
+		err = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE,
 				       "attempting get random");
 		if (err)
 			break;
 
-		recd = min_t(u32, be16_to_cpu(cmd.params.getrandom_out.size),
-			     num_bytes);
-		memcpy(dest, cmd.params.getrandom_out.buffer, recd);
+		out = (struct tpm2_get_random_out *) tpm_buf_out(&buf);
+
+		recd = min_t(u32, be16_to_cpu(out->size), num_bytes);
+		memcpy(dest, out->buffer, recd);
 
 		dest += recd;
 		total += recd;
@@ -370,16 +325,6 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max)
 	return total ? total : -EIO;
 }
 
-#define TPM2_GET_TPM_PT_IN_SIZE \
-	(sizeof(struct tpm_input_header) + \
-	 sizeof(struct tpm2_get_tpm_pt_in))
-
-static const struct tpm_input_header tpm2_get_tpm_pt_header = {
-	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
-	.length = cpu_to_be32(TPM2_GET_TPM_PT_IN_SIZE),
-	.ordinal = cpu_to_be32(TPM2_CC_GET_CAPABILITY)
-};
-
 /**
  * tpm2_get_tpm_pt() - get value of a TPM_CAP_TPM_PROPERTIES type property
  * @chip:		TPM chip to use.
@@ -391,33 +336,31 @@ static const struct tpm_input_header tpm2_get_tpm_pt_header = {
  * returned it remarks a POSIX error code. If a positive number is returned
  * it remarks a TPM error.
  */
-ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
+ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id, u32 *value,
 			const char *desc)
 {
-	struct tpm2_cmd cmd;
+	struct tpm_buf buf;
+	struct tpm2_get_tpm_pt_in in;
+	struct tpm2_get_tpm_pt_out *out;
 	int rc;
 
-	cmd.header.in = tpm2_get_tpm_pt_header;
-	cmd.params.get_tpm_pt_in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
-	cmd.params.get_tpm_pt_in.property_id = cpu_to_be32(property_id);
-	cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
+	tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_CAPABILITY);
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), desc);
-	if (!rc)
-		*value = cmd.params.get_tpm_pt_out.value;
+	in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
+	in.property_id = cpu_to_be32(property_id);
+	in.property_cnt = cpu_to_be32(1);
 
-	return rc;
-}
+	tpm_buf_append(&buf, (u8 *) &in, sizeof(in));
 
-#define TPM2_STARTUP_IN_SIZE \
-	(sizeof(struct tpm_input_header) + \
-	 sizeof(struct tpm2_startup_in))
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE, desc);
+	if (!rc) {
+		out = (struct tpm2_get_tpm_pt_out *)
+			&buf.data[TPM_HEADER_SIZE];
+		*value = be32_to_cpu(out->value);
+	}
 
-static const struct tpm_input_header tpm2_startup_header = {
-	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
-	.length = cpu_to_be32(TPM2_STARTUP_IN_SIZE),
-	.ordinal = cpu_to_be32(TPM2_CC_STARTUP)
-};
+	return rc;
+}
 
 /**
  * tpm2_startup() - send startup command to the TPM chip
@@ -431,26 +374,18 @@ static const struct tpm_input_header tpm2_startup_header = {
  */
 int tpm2_startup(struct tpm_chip *chip, u16 startup_type)
 {
-	struct tpm2_cmd cmd;
+	struct tpm_buf buf;
+	int rc;
 
-	cmd.header.in = tpm2_startup_header;
+	tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
+	tpm_buf_append_u16(&buf, startup_type);
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE,
+			      "attempting to start the TPM");
 
-	cmd.params.startup_in.startup_type = cpu_to_be16(startup_type);
-	return tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
-				"attempting to start the TPM");
+	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm2_startup);
 
-#define TPM2_SHUTDOWN_IN_SIZE \
-	(sizeof(struct tpm_input_header) + \
-	 sizeof(struct tpm2_startup_in))
-
-static const struct tpm_input_header tpm2_shutdown_header = {
-	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
-	.length = cpu_to_be32(TPM2_SHUTDOWN_IN_SIZE),
-	.ordinal = cpu_to_be32(TPM2_CC_SHUTDOWN)
-};
-
 /**
  * tpm2_shutdown() - send shutdown command to the TPM chip
  * @chip:		TPM chip to use.
@@ -459,20 +394,11 @@ static const struct tpm_input_header tpm2_shutdown_header = {
  */
 void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
 {
-	struct tpm2_cmd cmd;
-	int rc;
-
-	cmd.header.in = tpm2_shutdown_header;
-	cmd.params.startup_in.startup_type = cpu_to_be16(shutdown_type);
+	struct tpm_buf buf;
 
-	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), "stopping the TPM");
-
-	/* In places where shutdown command is sent there's no much we can do
-	 * except print the error code on a system failure.
-	 */
-	if (rc < 0)
-		dev_warn(chip->pdev, "transmit returned %d while stopping the TPM",
-			 rc);
+	tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
+	tpm_buf_append_u16(&buf, shutdown_type);
+	tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE, "stopping the TPM");
 }
 EXPORT_SYMBOL_GPL(tpm2_shutdown);
 
@@ -503,16 +429,6 @@ unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
 }
 EXPORT_SYMBOL_GPL(tpm2_calc_ordinal_duration);
 
-#define TPM2_SELF_TEST_IN_SIZE \
-	(sizeof(struct tpm_input_header) + \
-	 sizeof(struct tpm2_self_test_in))
-
-static const struct tpm_input_header tpm2_selftest_header = {
-	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
-	.length = cpu_to_be32(TPM2_SELF_TEST_IN_SIZE),
-	.ordinal = cpu_to_be32(TPM2_CC_SELF_TEST)
-};
-
 /**
  * tpm2_continue_selftest() - start a self test
  * @chip: TPM chip to use
@@ -525,13 +441,13 @@ static const struct tpm_input_header tpm2_selftest_header = {
  */
 static int tpm2_start_selftest(struct tpm_chip *chip, bool full)
 {
+	struct tpm_buf buf;
 	int rc;
-	struct tpm2_cmd cmd;
 
-	cmd.header.in = tpm2_selftest_header;
-	cmd.params.selftest_in.full_test = full;
+	tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+	tpm_buf_append_u8(&buf, full);
 
-	rc = tpm_transmit_cmd(chip, &cmd, TPM2_SELF_TEST_IN_SIZE,
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE,
 			      "continue selftest");
 
 	/* At least some prototype chips seem to give RC_TESTING error
@@ -562,11 +478,10 @@ int tpm2_do_selftest(struct tpm_chip *chip)
 	unsigned int loops;
 	unsigned int delay_msec = 100;
 	unsigned long duration;
-	struct tpm2_cmd cmd;
+	u8 dig[TPM_DIGEST_SIZE];
 	int i;
 
 	duration = tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST);
-
 	loops = jiffies_to_msecs(duration) / delay_msec;
 
 	rc = tpm2_start_selftest(chip, true);
@@ -574,21 +489,8 @@ int tpm2_do_selftest(struct tpm_chip *chip)
 		return rc;
 
 	for (i = 0; i < loops; i++) {
-		/* Attempt to read a PCR value */
-		cmd.header.in = tpm2_pcrread_header;
-		cmd.params.pcrread_in.pcr_selects_cnt = cpu_to_be32(1);
-		cmd.params.pcrread_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
-		cmd.params.pcrread_in.pcr_select_size = TPM2_PCR_SELECT_MIN;
-		cmd.params.pcrread_in.pcr_select[0] = 0x01;
-		cmd.params.pcrread_in.pcr_select[1] = 0x00;
-		cmd.params.pcrread_in.pcr_select[2] = 0x00;
-
-		rc = tpm_transmit_cmd(chip, (u8 *) &cmd, sizeof(cmd), NULL);
-		if (rc < 0)
-			break;
-
-		rc = be32_to_cpu(cmd.header.out.return_code);
-		if (rc != TPM2_RC_TESTING)
+		rc = tpm2_pcr_read(chip, 1, dig);
+		if (rc < 0 || rc != TPM2_RC_TESTING)
 			break;
 
 		msleep(delay_msec);
@@ -624,21 +526,24 @@ EXPORT_SYMBOL_GPL(tpm2_gen_interrupt);
  */
 int tpm2_probe(struct tpm_chip *chip)
 {
-	struct tpm2_cmd cmd;
+	struct tpm_buf buf;
+	struct tpm2_get_tpm_pt_in in;
 	int rc;
 
-	cmd.header.in = tpm2_get_tpm_pt_header;
-	cmd.params.get_tpm_pt_in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
-	cmd.params.get_tpm_pt_in.property_id = cpu_to_be32(0x100);
-	cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
+	in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
+	in.property_id = cpu_to_be32(0x100);
+	in.property_cnt = cpu_to_be32(1);
+
+	tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append(&buf, (u8 *) &in, sizeof(in));
 
-	rc = tpm_transmit(chip, (const char *) &cmd, sizeof(cmd));
+	rc = tpm_transmit(chip, buf.data, TPM_BUF_SIZE);
 	if (rc <  0)
 		return rc;
 	else if (rc < TPM_HEADER_SIZE)
 		return -EFAULT;
 
-	if (be16_to_cpu(cmd.header.out.tag) == TPM2_ST_NO_SESSIONS)
+	if (tpm_buf_tag(&buf) == TPM2_ST_NO_SESSIONS)
 		chip->flags |= TPM_CHIP_FLAG_TPM2;
 
 	return 0;
