diff --git a/include/tpm.h b/include/tpm.h
index 88aeba2..e4472d3 100644
--- a/include/tpm.h
+++ b/include/tpm.h
@@ -15,6 +15,17 @@
  * Specification for definitions of TPM commands.
  */
 
+#define TPM_HEADER_SIZE		10
+
+enum tpm_duration {
+	TPM_SHORT = 0,
+	TPM_MEDIUM = 1,
+	TPM_LONG = 2,
+	TPM_UNDEFINED,
+
+	TPM_DURATION_COUNT,
+};
+
 enum tpm_startup_type {
 	TPM_ST_CLEAR		= 0x0001,
 	TPM_ST_STATE		= 0x0002,
@@ -152,6 +163,187 @@
 	TPM_DEFEND_LOCK_RUNNING	= TPM_BASE + TPM_NON_FATAL + 3,
 };
 
+#ifdef CONFIG_DM_TPM
+
+/* Max buffer size supported by our tpm */
+#define TPM_DEV_BUFSIZE		1260
+
+/**
+ * struct tpm_chip_priv - Information about a TPM, stored by the uclass
+ *
+ * These values must be set up by the device's probe() method before
+ * communcation is attempted. If the device has an xfer() method, this is
+ * not needed. There is no need to set up @buf.
+ *
+ * @duration_ms:	Length of each duration type in milliseconds
+ * @retry_time_ms:	Time to wait before retrying receive
+ */
+struct tpm_chip_priv {
+	uint duration_ms[TPM_DURATION_COUNT];
+	uint retry_time_ms;
+	u8 buf[TPM_DEV_BUFSIZE + sizeof(u8)];  /* Max buffer size + addr */
+};
+
+/**
+ * struct tpm_ops - low-level TPM operations
+ *
+ * These are designed to avoid loops and delays in the driver itself. These
+ * should be handled in the uclass.
+ *
+ * In gneral you should implement everything except xfer(). Where you need
+ * complete control of the transfer, then xfer() can be provided and will
+ * override the other methods.
+ *
+ * This interface is for low-level TPM access. It does not understand the
+ * concept of localities or the various TPM messages. That interface is
+ * defined in the functions later on in this file, but they all translate
+ * to bytes which are sent and received.
+ */
+struct tpm_ops {
+	/**
+	 * open() - Request access to locality 0 for the caller
+	 *
+	 * After all commands have been completed the caller should call
+	 * close().
+	 *
+	 * @dev:	Device to close
+	 * @return 0 ok OK, -ve on error
+	 */
+	int (*open)(struct udevice *dev);
+
+	/**
+	 * close() - Close the current session
+	 *
+	 * Releasing the locked locality. Returns 0 on success, -ve 1 on
+	 * failure (in case lock removal did not succeed).
+	 *
+	 * @dev:	Device to close
+	 * @return 0 ok OK, -ve on error
+	 */
+	int (*close)(struct udevice *dev);
+
+	/**
+	 * get_desc() - Get a text description of the TPM
+	 *
+	 * @dev:	Device to check
+	 * @buf:	Buffer to put the string
+	 * @size:	Maximum size of buffer
+	 * @return length of string, or -ENOSPC it no space
+	 */
+	int (*get_desc)(struct udevice *dev, char *buf, int size);
+
+	/**
+	 * send() - send data to the TPM
+	 *
+	 * @dev:	Device to talk to
+	 * @sendbuf:	Buffer of the data to send
+	 * @send_size:	Size of the data to send
+	 *
+	 * Returns 0 on success or -ve on failure.
+	 */
+	int (*send)(struct udevice *dev, const uint8_t *sendbuf,
+		    size_t send_size);
+
+	/**
+	 * recv() - receive a response from the TPM
+	 *
+	 * @dev:	Device to talk to
+	 * @recvbuf:	Buffer to save the response to
+	 * @max_size:	Maximum number of bytes to receive
+	 *
+	 * Returns number of bytes received on success, -EAGAIN if the TPM
+	 * response is not ready, -EINTR if cancelled, or other -ve value on
+	 * failure.
+	 */
+	int (*recv)(struct udevice *dev, uint8_t *recvbuf, size_t max_size);
+
+	/**
+	 * cleanup() - clean up after an operation in progress
+	 *
+	 * This is called if receiving times out. The TPM may need to abort
+	 * the current transaction if it did not complete, and make itself
+	 * ready for another.
+	 *
+	 * @dev:	Device to talk to
+	 */
+	int (*cleanup)(struct udevice *dev);
+
+	/**
+	 * xfer() - send data to the TPM and get response
+	 *
+	 * This method is optional. If it exists it is used in preference
+	 * to send(), recv() and cleanup(). It should handle all aspects of
+	 * TPM communication for a single transfer.
+	 *
+	 * @dev:	Device to talk to
+	 * @sendbuf:	Buffer of the data to send
+	 * @send_size:	Size of the data to send
+	 * @recvbuf:	Buffer to save the response to
+	 * @recv_size:	Pointer to the size of the response buffer
+	 *
+	 * Returns 0 on success (and places the number of response bytes at
+	 * recv_size) or -ve on failure.
+	 */
+	int (*xfer)(struct udevice *dev, const uint8_t *sendbuf,
+		    size_t send_size, uint8_t *recvbuf, size_t *recv_size);
+};
+
+#define tpm_get_ops(dev)        ((struct tpm_ops *)device_get_ops(dev))
+
+/**
+ * tpm_open() - Request access to locality 0 for the caller
+ *
+ * After all commands have been completed the caller is supposed to
+ * call tpm_close().
+ *
+ * Returns 0 on success, -ve on failure.
+ */
+int tpm_open(struct udevice *dev);
+
+/**
+ * tpm_close() - Close the current session
+ *
+ * Releasing the locked locality. Returns 0 on success, -ve 1 on
+ * failure (in case lock removal did not succeed).
+ */
+int tpm_close(struct udevice *dev);
+
+/**
+ * tpm_get_desc() - Get a text description of the TPM
+ *
+ * @dev:	Device to check
+ * @buf:	Buffer to put the string
+ * @size:	Maximum size of buffer
+ * @return length of string, or -ENOSPC it no space
+ */
+int tpm_get_desc(struct udevice *dev, char *buf, int size);
+
+/**
+ * tpm_xfer() - send data to the TPM and get response
+ *
+ * This first uses the device's send() method to send the bytes. Then it calls
+ * recv() to get the reply. If recv() returns -EAGAIN then it will delay a
+ * short time and then call recv() again.
+ *
+ * Regardless of whether recv() completes successfully, it will then call
+ * cleanup() to finish the transaction.
+ *
+ * Note that the outgoing data is inspected to determine command type
+ * (ordinal) and a timeout is used for that command type.
+ *
+ * @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 -ve on failure.
+ */
+int tpm_xfer(struct udevice *dev, const uint8_t *sendbuf, size_t send_size,
+	     uint8_t *recvbuf, size_t *recv_size);
+
+#endif /* CONFIG_DM_TPM */
+
 /**
  * Initialize TPM device.  It must be called before any TPM commands.
  *