diff --git a/README b/README
index 434384c..badb834 100644
--- a/README
+++ b/README
@@ -1076,6 +1076,19 @@ The following options need to be configured:
 		CONFIG_TPM
 		Support TPM devices.
 
+		CONFIG_TPM_TIS_I2C
+		Support for i2c bus TPM devices. Only one device
+		per system is supported at this time.
+
+			CONFIG_TPM_TIS_I2C_BUS_NUMBER
+			Define the the i2c bus number for the TPM device
+
+			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
+			Define the TPM's address on the i2c bus
+
+			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
+			Define the burst count bytes upper limit
+
 		CONFIG_TPM_TIS_LPC
 		Support for generic parallel port TPM devices. Only one device
 		per system is supported at this time.
diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
index 47d09de..cb29bab 100644
--- a/drivers/tpm/Makefile
+++ b/drivers/tpm/Makefile
@@ -23,7 +23,10 @@ include $(TOPDIR)/config.mk
 
 LIB := $(obj)libtpm.o
 
-COBJS-$(CONFIG_TPM_TIS_LPC) = tpm_tis_lpc.o
+# TODO(clchiou): Merge tpm_tis_lpc.c with tpm.c
+COBJS-$(CONFIG_TPM_TIS_I2C) += tpm.o
+COBJS-$(CONFIG_TPM_TIS_I2C) += tpm_tis_i2c.o
+COBJS-$(CONFIG_TPM_TIS_LPC) += tpm_tis_lpc.o
 
 COBJS	:= $(COBJS-y)
 SRCS	:= $(COBJS:.o=.c)
diff --git a/drivers/tpm/tpm.c b/drivers/tpm/tpm.c
new file mode 100644
index 0000000..785ed01
--- /dev/null
+++ b/drivers/tpm/tpm.c
@@ -0,0 +1,466 @@
+/*
+ * Copyright (C) 2011 Infineon Technologies
+ *
+ * Authors:
+ * Peter Huewe <huewe.external@infineon.com>
+ *
+ * Description:
+ * Device driver for TCG/TCPA TPM (trusted platform module).
+ * Specifications at www.trustedcomputinggroup.org
+ *
+ * It is based on the Linux kernel driver tpm.c from Leendert van
+ * Dorn, Dave Safford, Reiner Sailer, and Kyleen Hall.
+ *
+ * Version: 2.1.1
+ *
+ * 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, version 2 of the
+ * License.
+ *
+ * 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 <compiler.h>
+#include <i2c.h>
+#include <tpm.h>
+#include <asm-generic/errno.h>
+#include <linux/types.h>
+#include <linux/unaligned/be_byteshift.h>
+
+#include "tpm_private.h"
+
+/* Global structure for tpm chip data */
+static struct tpm_chip tpm_chip;
+
+enum tpm_duration {
+	TPM_SHORT = 0,
+	TPM_MEDIUM = 1,
+	TPM_LONG = 2,
+	TPM_UNDEFINED,
+};
+
+/* Extended error numbers from linux (see errno.h) */
+#define	ECANCELED	125	/* Operation Canceled */
+
+/* Timer frequency. Corresponds to msec timer resolution*/
+#define HZ 1000
+
+#define TPM_MAX_ORDINAL			243
+#define TPM_MAX_PROTECTED_ORDINAL	12
+#define TPM_PROTECTED_ORDINAL_MASK	0xFF
+
+#define TPM_CMD_COUNT_BYTE	2
+#define TPM_CMD_ORDINAL_BYTE	6
+
+/*
+ * Array with one entry per ordinal defining the maximum amount
+ * of time the chip could take to return the result.  The ordinal
+ * designation of short, medium or long is defined in a table in
+ * TCG Specification TPM Main Part 2 TPM Structures Section 17. The
+ * values of the SHORT, MEDIUM, and LONG durations are retrieved
+ * from the chip during initialization with a call to tpm_get_timeouts.
+ */
+static const u8 tpm_protected_ordinal_duration[TPM_MAX_PROTECTED_ORDINAL] = {
+	TPM_UNDEFINED,		/* 0 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 5 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 10 */
+	TPM_SHORT,
+};
+
+static const u8 tpm_ordinal_duration[TPM_MAX_ORDINAL] = {
+	TPM_UNDEFINED,		/* 0 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 5 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 10 */
+	TPM_SHORT,
+	TPM_MEDIUM,
+	TPM_LONG,
+	TPM_LONG,
+	TPM_MEDIUM,		/* 15 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_MEDIUM,
+	TPM_LONG,
+	TPM_SHORT,		/* 20 */
+	TPM_SHORT,
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_SHORT,		/* 25 */
+	TPM_SHORT,
+	TPM_MEDIUM,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_MEDIUM,		/* 30 */
+	TPM_LONG,
+	TPM_MEDIUM,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,		/* 35 */
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_MEDIUM,		/* 40 */
+	TPM_LONG,
+	TPM_MEDIUM,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,		/* 45 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_LONG,
+	TPM_MEDIUM,		/* 50 */
+	TPM_MEDIUM,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 55 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_MEDIUM,		/* 60 */
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_MEDIUM,		/* 65 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 70 */
+	TPM_SHORT,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 75 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_LONG,		/* 80 */
+	TPM_UNDEFINED,
+	TPM_MEDIUM,
+	TPM_LONG,
+	TPM_SHORT,
+	TPM_UNDEFINED,		/* 85 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 90 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_UNDEFINED,		/* 95 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_MEDIUM,		/* 100 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 105 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 110 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,		/* 115 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_LONG,		/* 120 */
+	TPM_LONG,
+	TPM_MEDIUM,
+	TPM_UNDEFINED,
+	TPM_SHORT,
+	TPM_SHORT,		/* 125 */
+	TPM_SHORT,
+	TPM_LONG,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,		/* 130 */
+	TPM_MEDIUM,
+	TPM_UNDEFINED,
+	TPM_SHORT,
+	TPM_MEDIUM,
+	TPM_UNDEFINED,		/* 135 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 140 */
+	TPM_SHORT,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 145 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 150 */
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_UNDEFINED,		/* 155 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 160 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 165 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_LONG,		/* 170 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 175 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_MEDIUM,		/* 180 */
+	TPM_SHORT,
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_MEDIUM,		/* 185 */
+	TPM_SHORT,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 190 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 195 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 200 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,
+	TPM_SHORT,		/* 205 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_MEDIUM,		/* 210 */
+	TPM_UNDEFINED,
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_MEDIUM,
+	TPM_UNDEFINED,		/* 215 */
+	TPM_MEDIUM,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,
+	TPM_SHORT,		/* 220 */
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_SHORT,
+	TPM_UNDEFINED,		/* 225 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 230 */
+	TPM_LONG,
+	TPM_MEDIUM,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,		/* 235 */
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_UNDEFINED,
+	TPM_SHORT,		/* 240 */
+	TPM_UNDEFINED,
+	TPM_MEDIUM,
+};
+
+/* Returns max number of milliseconds to wait */
+static
+unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
+{
+	int duration_idx = TPM_UNDEFINED;
+	int duration = 0;
+
+	if (ordinal < TPM_MAX_ORDINAL) {
+		duration_idx = tpm_ordinal_duration[ordinal];
+	} else if ((ordinal & TPM_PROTECTED_ORDINAL_MASK) <
+			TPM_MAX_PROTECTED_ORDINAL) {
+		duration_idx = tpm_protected_ordinal_duration[
+			ordinal & TPM_PROTECTED_ORDINAL_MASK];
+	}
+
+	if (duration_idx != TPM_UNDEFINED)
+		duration = chip->vendor.duration[duration_idx];
+
+	if (duration <= 0)
+		return 2 * 60 * HZ;  /* Two minutes timeout */
+	else
+		return duration;
+}
+
+int tis_sendrecv(const uint8_t *sendbuf, size_t send_size, uint8_t *recvbuf,
+		size_t *recv_len)
+{
+	ssize_t rc;
+	u8 status;
+	u32 count, ordinal;
+	unsigned long start, stop;
+
+	if (send_size < max(TPM_CMD_COUNT_BYTE, TPM_CMD_ORDINAL_BYTE) + 4) {
+		error("invalid send_size %zx\n", send_size);
+		return -EOVERFLOW;
+	}
+
+	/* Switch endianess: big->little */
+	count = get_unaligned_be32(sendbuf + TPM_CMD_COUNT_BYTE);
+	ordinal = get_unaligned_be32(sendbuf + TPM_CMD_ORDINAL_BYTE);
+	if (count == 0) {
+		error("no data\n");
+		return -ENODATA;
+	}
+	if (count > send_size) {
+		error("invalid count value %x %zx\n", count, send_size);
+		return -EOVERFLOW;
+	}
+
+	rc = tpm_chip.vendor.send(&tpm_chip, (u8 *)sendbuf, count);
+	if (rc < 0) {
+		error("tpm_send: error %zd\n", rc);
+		goto out;
+	}
+
+	start = get_timer(0);
+	stop = tpm_calc_ordinal_duration(&tpm_chip, ordinal);
+	do {
+		debug("%s: waiting for status...\n", __func__);
+		status = tpm_chip.vendor.status(&tpm_chip);
+		if ((status & tpm_chip.vendor.req_complete_mask) ==
+				tpm_chip.vendor.req_complete_val) {
+			debug("%s: ...got it;\n", __func__);
+			goto out_recv;
+		}
+
+		if ((status == tpm_chip.vendor.req_canceled)) {
+			error("operation canceled\n");
+			rc = -ECANCELED;
+			goto out;
+		}
+		udelay(TPM_TIMEOUT * 1000);
+	} while (get_timer(start) < stop);
+
+	tpm_chip.vendor.cancel(&tpm_chip);
+	error("operation timed out\n");
+	rc = -ETIME;
+	goto out;
+
+out_recv:
+	debug("%s: out_recv: reading response...\n", __func__);
+	rc = tpm_chip.vendor.recv(&tpm_chip, (u8 *)recvbuf, *recv_len);
+	if (rc >= 0)
+		*recv_len = rc;
+	else
+		error("tpm_recv: error %zd\n", rc);
+
+out:
+	return rc >= 0 ? 0 : rc;
+}
+
+struct tpm_chip *tpm_register_hardware(const struct tpm_vendor_specific *vendor)
+{
+	/* Driver specific per-device data */
+	memcpy(&tpm_chip.vendor, vendor, sizeof(*vendor));
+	tpm_chip.is_open = 1;
+
+	return &tpm_chip;
+}
+
+int tis_init(void)
+{
+	return tpm_vendor_init();
+}
+
+int tis_open(void)
+{
+	int rc;
+
+	if (tpm_chip.is_open)
+		return -EBUSY;
+
+	rc = tpm_vendor_open();
+
+	if (rc < 0)
+		tpm_chip.is_open = 0;
+
+	return rc;
+}
+
+int tis_close(void)
+{
+	if (!tpm_chip.is_open)
+		return -EIO;
+
+	tpm_vendor_cleanup(&tpm_chip);
+	tpm_chip.is_open = 0;
+
+	return 0;
+}
diff --git a/drivers/tpm/tpm_private.h b/drivers/tpm/tpm_private.h
new file mode 100644
index 0000000..87ae444
--- /dev/null
+++ b/drivers/tpm/tpm_private.h
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2011 Infineon Technologies
+ *
+ * Authors:
+ * Peter Huewe <huewe.external@infineon.com>
+ *
+ * Version: 2.1.1
+ *
+ * Description:
+ * Device driver for TCG/TCPA TPM (trusted platform module).
+ * Specifications at www.trustedcomputinggroup.org
+ *
+ * It is based on the Linux kernel driver tpm.c from Leendert van
+ * Dorn, Dave Safford, Reiner Sailer, and Kyleen Hall.
+ *
+ *
+ * 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, version 2 of the
+ * License.
+ *
+ * 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 _TPM_PRIVATE_H_
+#define _TPM_PRIVATE_H_
+
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+enum tpm_timeout {
+	TPM_TIMEOUT = 5,	/* msecs */
+};
+
+/* Index of Count field in TPM response buffer */
+#define TPM_RSP_SIZE_BYTE	2
+#define TPM_RSP_RC_BYTE		6
+
+struct tpm_chip;
+
+struct tpm_vendor_specific {
+	const u8 req_complete_mask;
+	const u8 req_complete_val;
+	const u8 req_canceled;
+	int (*recv) (struct tpm_chip *, u8 *, size_t);
+	int (*send) (struct tpm_chip *, u8 *, size_t);
+	void (*cancel) (struct tpm_chip *);
+	u8(*status) (struct tpm_chip *);
+	int locality;
+	unsigned long timeout_a, timeout_b, timeout_c, timeout_d;  /* msec */
+	unsigned long duration[3];  /* msec */
+};
+
+struct tpm_chip {
+	int is_open;
+	struct tpm_vendor_specific vendor;
+};
+
+struct tpm_input_header {
+	__be16 tag;
+	__be32 length;
+	__be32 ordinal;
+} __packed;
+
+struct tpm_output_header {
+	__be16 tag;
+	__be32 length;
+	__be32 return_code;
+} __packed;
+
+struct timeout_t {
+	__be32 a;
+	__be32 b;
+	__be32 c;
+	__be32 d;
+} __packed;
+
+struct duration_t {
+	__be32 tpm_short;
+	__be32 tpm_medium;
+	__be32 tpm_long;
+} __packed;
+
+union cap_t {
+	struct timeout_t timeout;
+	struct duration_t duration;
+};
+
+struct tpm_getcap_params_in {
+	__be32 cap;
+	__be32 subcap_size;
+	__be32 subcap;
+} __packed;
+
+struct tpm_getcap_params_out {
+	__be32 cap_size;
+	union cap_t cap;
+} __packed;
+
+union tpm_cmd_header {
+	struct tpm_input_header in;
+	struct tpm_output_header out;
+};
+
+union tpm_cmd_params {
+	struct tpm_getcap_params_out getcap_out;
+	struct tpm_getcap_params_in getcap_in;
+};
+
+struct tpm_cmd_t {
+	union tpm_cmd_header header;
+	union tpm_cmd_params params;
+} __packed;
+
+struct tpm_chip *tpm_register_hardware(const struct tpm_vendor_specific *);
+
+int tpm_vendor_init(void);
+
+int tpm_vendor_open(void);
+
+void tpm_vendor_cleanup(struct tpm_chip *chip);
+
+#endif  /* _TPM_PRIVATE_H_ */
diff --git a/drivers/tpm/tpm_tis_i2c.c b/drivers/tpm/tpm_tis_i2c.c
new file mode 100644
index 0000000..5f34370
--- /dev/null
+++ b/drivers/tpm/tpm_tis_i2c.c
@@ -0,0 +1,587 @@
+/*
+ * Copyright (C) 2011 Infineon Technologies
+ *
+ * Authors:
+ * Peter Huewe <huewe.external@infineon.com>
+ *
+ * Description:
+ * Device driver for TCG/TCPA TPM (trusted platform module).
+ * Specifications at www.trustedcomputinggroup.org
+ *
+ * This device driver implements the TPM interface as defined in
+ * the TCG TPM Interface Spec version 1.2, revision 1.0 and the
+ * Infineon I2C Protocol Stack Specification v0.20.
+ *
+ * It is based on the Linux kernel driver tpm.c from Leendert van
+ * Dorn, Dave Safford, Reiner Sailer, and Kyleen Hall.
+ *
+ * Version: 2.1.1
+ *
+ * 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, version 2 of the
+ * License.
+ *
+ * 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 <compiler.h>
+#include <i2c.h>
+#include <tpm.h>
+#include <asm-generic/errno.h>
+#include <linux/types.h>
+#include <linux/unaligned/be_byteshift.h>
+
+#include "tpm_private.h"
+
+/* Max buffer size supported by our tpm */
+#define TPM_DEV_BUFSIZE		1260
+
+/* Max number of iterations after i2c NAK */
+#define MAX_COUNT		3
+/*
+ * Max number of iterations after i2c NAK for 'long' commands
+ *
+ * We need this especially for sending TPM_READY, since the cleanup after the
+ * transtion to the ready state may take some time, but it is unpredictable
+ * how long it will take.
+ */
+#define MAX_COUNT_LONG		50
+
+#define SLEEP_DURATION		60	/* in usec */
+#define SLEEP_DURATION_LONG	210	/* in usec */
+
+#define TPM_HEADER_SIZE		10
+
+/*
+ * Expected value for DIDVID register
+ *
+ * The only device the system knows about at this moment is Infineon slb9635.
+ */
+#define TPM_TIS_I2C_DID_VID	0x000b15d1L
+
+enum tis_access {
+	TPM_ACCESS_VALID		= 0x80,
+	TPM_ACCESS_ACTIVE_LOCALITY	= 0x20,
+	TPM_ACCESS_REQUEST_PENDING	= 0x04,
+	TPM_ACCESS_REQUEST_USE		= 0x02,
+};
+
+enum tis_status {
+	TPM_STS_VALID			= 0x80,
+	TPM_STS_COMMAND_READY		= 0x40,
+	TPM_STS_GO			= 0x20,
+	TPM_STS_DATA_AVAIL		= 0x10,
+	TPM_STS_DATA_EXPECT		= 0x08,
+};
+
+enum tis_defaults {
+	TIS_SHORT_TIMEOUT		= 750,	/* ms */
+	TIS_LONG_TIMEOUT		= 2000,	/* 2 sec */
+};
+
+/*
+ * XXX: WARNING: i2c read/write functions must be able to NOT prepending slave
+ * register address to payload, when addr=alen=0, because TPM chip expects
+ * messages not coming with a register address.
+ */
+#define TPM_TIS_I2C_READ(chip, buf, len) i2c_read(chip, 0, 0, buf, len)
+#define TPM_TIS_I2C_WRITE(chip, buf, len) i2c_write(chip, 0, 0, buf, len)
+
+#define TPM_ACCESS(l)			(0x0000 | ((l) << 4))
+#define TPM_STS(l)			(0x0001 | ((l) << 4))
+#define TPM_DATA_FIFO(l)		(0x0005 | ((l) << 4))
+#define TPM_DID_VID(l)			(0x0006 | ((l) << 4))
+
+/* Structure to store I2C TPM specific stuff */
+struct tpm_dev {
+	uint addr;
+	u8 buf[TPM_DEV_BUFSIZE + sizeof(u8)];  /* Max buffer size + addr */
+};
+
+static struct tpm_dev tpm_dev = {
+	.addr = CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
+};
+
+/*
+ * iic_tpm_read() - read from TPM register
+ * @addr: register address to read from
+ * @buffer: provided by caller
+ * @len: number of bytes to read
+ *
+ * Read len bytes from TPM register and put them into
+ * buffer (little-endian format, i.e. first byte is put into buffer[0]).
+ *
+ * NOTE: TPM is big-endian for multi-byte values. Multi-byte
+ * values have to be swapped.
+ *
+ * Return -EIO on error, 0 on success.
+ */
+static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
+{
+	int rc;
+	int count;
+	uint32_t addrbuf = addr;
+
+	for (count = 0; count < MAX_COUNT; count++) {
+		rc = TPM_TIS_I2C_WRITE(tpm_dev.addr, (uchar *)&addrbuf, 1);
+		if (rc == 0)
+			break;  /* Success, break to skip sleep */
+		udelay(SLEEP_DURATION);
+	}
+	if (rc)
+		return -rc;
+
+	/*
+	 * After the TPM has successfully received the register address it needs
+	 * some time, thus we're sleeping here again, before retrieving the data
+	 */
+	for (count = 0; count < MAX_COUNT; count++) {
+		udelay(SLEEP_DURATION);
+		rc = TPM_TIS_I2C_READ(tpm_dev.addr, buffer, len);
+		if (rc == 0)
+			break;  /* Success, break to skip sleep */
+	}
+	if (rc)
+		return -rc;
+
+	return 0;
+}
+
+static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len,
+		unsigned int sleep_time, u8 max_count)
+{
+	int rc = 0;
+	int count;
+
+	/* Prepare send buffer */
+	tpm_dev.buf[0] = addr;
+	memcpy(&(tpm_dev.buf[1]), buffer, len);
+
+	for (count = 0; count < max_count; count++) {
+		rc = TPM_TIS_I2C_WRITE(tpm_dev.addr, tpm_dev.buf, len + 1);
+		if (rc == 0)
+			break;  /* Success, break to skip sleep */
+		udelay(sleep_time);
+	}
+	if (rc)
+		return -rc;
+
+	return 0;
+}
+
+/*
+ * iic_tpm_write() - write to TPM register
+ * @addr: register address to write to
+ * @buffer: containing data to be written
+ * @len: number of bytes to write
+ *
+ * Write len bytes from provided buffer to TPM register (little
+ * endian format, i.e. buffer[0] is written as first byte).
+ *
+ * NOTE: TPM is big-endian for multi-byte values. Multi-byte
+ * values have to be swapped.
+ *
+ * NOTE: use this function instead of the iic_tpm_write_generic function.
+ *
+ * Return -EIO on error, 0 on success
+ */
+static int iic_tpm_write(u8 addr, u8 *buffer, size_t len)
+{
+	return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION,
+			MAX_COUNT);
+}
+
+/*
+ * This function is needed especially for the cleanup situation after
+ * sending TPM_READY
+ */
+static int iic_tpm_write_long(u8 addr, u8 *buffer, size_t len)
+{
+	return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LONG,
+			MAX_COUNT_LONG);
+}
+
+static int check_locality(struct tpm_chip *chip, int loc)
+{
+	const u8 mask = TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID;
+	u8 buf;
+	int rc;
+
+	rc = iic_tpm_read(TPM_ACCESS(loc), &buf, 1);
+	if (rc < 0)
+		return rc;
+
+	if ((buf & mask) == mask) {
+		chip->vendor.locality = loc;
+		return loc;
+	}
+
+	return -1;
+}
+
+static void release_locality(struct tpm_chip *chip, int loc, int force)
+{
+	const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;
+	u8 buf;
+
+	if (iic_tpm_read(TPM_ACCESS(loc), &buf, 1) < 0)
+		return;
+
+	if (force || (buf & mask) == mask) {
+		buf = TPM_ACCESS_ACTIVE_LOCALITY;
+		iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
+	}
+}
+
+static int request_locality(struct tpm_chip *chip, int loc)
+{
+	unsigned long start, stop;
+	u8 buf = TPM_ACCESS_REQUEST_USE;
+
+	if (check_locality(chip, loc) >= 0)
+		return loc;  /* We already have the locality */
+
+	iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
+
+	/* Wait for burstcount */
+	start = get_timer(0);
+	stop = chip->vendor.timeout_a;
+	do {
+		if (check_locality(chip, loc) >= 0)
+			return loc;
+		udelay(TPM_TIMEOUT * 1000);
+	} while (get_timer(start) < stop);
+
+	return -1;
+}
+
+static u8 tpm_tis_i2c_status(struct tpm_chip *chip)
+{
+	/* NOTE: Since i2c read may fail, return 0 in this case --> time-out */
+	u8 buf;
+
+	if (iic_tpm_read(TPM_STS(chip->vendor.locality), &buf, 1) < 0)
+		return 0;
+	else
+		return buf;
+}
+
+static void tpm_tis_i2c_ready(struct tpm_chip *chip)
+{
+	/* This causes the current command to be aborted */
+	u8 buf = TPM_STS_COMMAND_READY;
+
+	iic_tpm_write_long(TPM_STS(chip->vendor.locality), &buf, 1);
+}
+
+static ssize_t get_burstcount(struct tpm_chip *chip)
+{
+	unsigned long start, stop;
+	ssize_t burstcnt;
+	u8 addr, buf[3];
+
+	/* Wait for burstcount */
+	/* XXX: Which timeout value? Spec has 2 answers (c & d) */
+	start = get_timer(0);
+	stop = chip->vendor.timeout_d;
+	do {
+		/* Note: STS is little endian */
+		addr = TPM_STS(chip->vendor.locality) + 1;
+		if (iic_tpm_read(addr, buf, 3) < 0)
+			burstcnt = 0;
+		else
+			burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];
+
+		if (burstcnt)
+			return burstcnt;
+		udelay(TPM_TIMEOUT * 1000);
+	} while (get_timer(start) < stop);
+
+	return -EBUSY;
+}
+
+static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
+		int *status)
+{
+	unsigned long start, stop;
+
+	/* Check current status */
+	*status = tpm_tis_i2c_status(chip);
+	if ((*status & mask) == mask)
+		return 0;
+
+	start = get_timer(0);
+	stop = timeout;
+	do {
+		udelay(TPM_TIMEOUT * 1000);
+		*status = tpm_tis_i2c_status(chip);
+		if ((*status & mask) == mask)
+			return 0;
+	} while (get_timer(start) < stop);
+
+	return -ETIME;
+}
+
+static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+	size_t size = 0;
+	ssize_t burstcnt;
+	int rc;
+
+	while (size < count) {
+		burstcnt = get_burstcount(chip);
+
+		/* burstcount < 0 -> tpm is busy */
+		if (burstcnt < 0)
+			return burstcnt;
+
+		/* Limit received data to max left */
+		if (burstcnt > (count - size))
+			burstcnt = count - size;
+
+		rc = iic_tpm_read(TPM_DATA_FIFO(chip->vendor.locality),
+				&(buf[size]), burstcnt);
+		if (rc == 0)
+			size += burstcnt;
+	}
+
+	return size;
+}
+
+static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+	int size = 0;
+	int expected, status;
+
+	if (count < TPM_HEADER_SIZE) {
+		size = -EIO;
+		goto out;
+	}
+
+	/* Read first 10 bytes, including tag, paramsize, and result */
+	size = recv_data(chip, buf, TPM_HEADER_SIZE);
+	if (size < TPM_HEADER_SIZE) {
+		error("Unable to read header\n");
+		goto out;
+	}
+
+	expected = get_unaligned_be32(buf + TPM_RSP_SIZE_BYTE);
+	if ((size_t)expected > count) {
+		size = -EIO;
+		goto out;
+	}
+
+	size += recv_data(chip, &buf[TPM_HEADER_SIZE],
+			expected - TPM_HEADER_SIZE);
+	if (size < expected) {
+		error("Unable to read remainder of result\n");
+		size = -ETIME;
+		goto out;
+	}
+
+	wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
+	if (status & TPM_STS_DATA_AVAIL) {  /* Retry? */
+		error("Error left over data\n");
+		size = -EIO;
+		goto out;
+	}
+
+out:
+	tpm_tis_i2c_ready(chip);
+	/*
+	 * The TPM needs some time to clean up here,
+	 * so we sleep rather than keeping the bus busy
+	 */
+	udelay(2000);
+	release_locality(chip, chip->vendor.locality, 0);
+
+	return size;
+}
+
+static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
+{
+	int rc, status;
+	ssize_t burstcnt;
+	size_t count = 0;
+	int retry = 0;
+	u8 sts = TPM_STS_GO;
+
+	if (len > TPM_DEV_BUFSIZE)
+		return -E2BIG;  /* Command is too long for our tpm, sorry */
+
+	if (request_locality(chip, 0) < 0)
+		return -EBUSY;
+
+	status = tpm_tis_i2c_status(chip);
+	if ((status & TPM_STS_COMMAND_READY) == 0) {
+		tpm_tis_i2c_ready(chip);
+		if (wait_for_stat(chip, TPM_STS_COMMAND_READY,
+					chip->vendor.timeout_b, &status) < 0) {
+			rc = -ETIME;
+			goto out_err;
+		}
+	}
+
+	burstcnt = get_burstcount(chip);
+
+	/* burstcount < 0 = tpm is busy */
+	if (burstcnt < 0)
+		return burstcnt;
+
+	while (count < len - 1) {
+		if (burstcnt > len - 1 - count)
+			burstcnt = len - 1 - count;
+
+#ifdef CONFIG_TPM_TIS_I2C_BURST_LIMITATION
+		if (retry && burstcnt > CONFIG_TPM_TIS_I2C_BURST_LIMITATION)
+			burstcnt = CONFIG_TPM_TIS_I2C_BURST_LIMITATION;
+#endif /* CONFIG_TPM_TIS_I2C_BURST_LIMITATION */
+
+		rc = iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality),
+				&(buf[count]), burstcnt);
+		if (rc == 0)
+			count += burstcnt;
+		else {
+			retry++;
+			wait_for_stat(chip, TPM_STS_VALID,
+					chip->vendor.timeout_c, &status);
+
+			if ((status & TPM_STS_DATA_EXPECT) == 0) {
+				rc = -EIO;
+				goto out_err;
+			}
+		}
+
+	}
+
+	/* Write last byte */
+	iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality), &(buf[count]), 1);
+	wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
+	if ((status & TPM_STS_DATA_EXPECT) != 0) {
+		rc = -EIO;
+		goto out_err;
+	}
+
+	/* Go and do it */
+	iic_tpm_write(TPM_STS(chip->vendor.locality), &sts, 1);
+
+	return len;
+
+out_err:
+	tpm_tis_i2c_ready(chip);
+	/*
+	 * The TPM needs some time to clean up here,
+	 * so we sleep rather than keeping the bus busy
+	 */
+	udelay(2000);
+	release_locality(chip, chip->vendor.locality, 0);
+
+	return rc;
+}
+
+static struct tpm_vendor_specific tpm_tis_i2c = {
+	.status = tpm_tis_i2c_status,
+	.recv = tpm_tis_i2c_recv,
+	.send = tpm_tis_i2c_send,
+	.cancel = tpm_tis_i2c_ready,
+	.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+	.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+	.req_canceled = TPM_STS_COMMAND_READY,
+};
+
+int tpm_vendor_init(void)
+{
+	int rc;
+
+	rc = i2c_set_bus_num(CONFIG_TPM_TIS_I2C_BUS_NUMBER);
+	if (rc) {
+		debug("%s: fail: i2c_set_bus_num(0x%x) return %d\n", __func__,
+				CONFIG_TPM_TIS_I2C_BUS_NUMBER, rc);
+		return rc;
+	}
+
+	/*
+	 * i2c_probe() could fail in the first time because TPM chip may fall
+	 * asleep sometimes.  But the TPM chip should wake up on the first i2c
+	 * probe, and the second i2c probe should succeed.
+	 */
+	if (i2c_probe(CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS)) {
+		rc = i2c_probe(CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS);
+		if (rc) {
+			debug("%s: fail: i2c_probe(0x%x) return %d\n", __func__,
+					CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS, rc);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+int tpm_vendor_open(void)
+{
+	u32 vendor;
+	int rc = 0;
+	struct tpm_chip *chip;
+
+	chip = tpm_register_hardware(&tpm_tis_i2c);
+	if (!chip) {
+		rc = -ENODEV;
+		goto out_err;
+	}
+
+	/* Default timeouts */
+	chip->vendor.timeout_a = TIS_SHORT_TIMEOUT;
+	chip->vendor.timeout_b = TIS_LONG_TIMEOUT;
+	chip->vendor.timeout_c = TIS_SHORT_TIMEOUT;
+	chip->vendor.timeout_d = TIS_SHORT_TIMEOUT;
+
+	if (request_locality(chip, 0) < 0) {
+		rc = -ENODEV;
+		goto out_err;
+	}
+
+	/* Read four bytes from DID_VID register */
+	if (iic_tpm_read(TPM_DID_VID(0), (uchar *)&vendor, 4) < 0) {
+		rc = -EIO;
+		goto out_release;
+	}
+	/* Create DID_VID register value, after swapping to little-endian */
+	vendor = be32_to_cpu(vendor);
+	if (vendor != TPM_TIS_I2C_DID_VID) {
+		rc = -ENODEV;
+		goto out_release;
+	}
+
+	debug("1.2 TPM (device-id 0x%X)\n", vendor >> 16);
+
+	/*
+	 * A timeout query to TPM can be placed here.
+	 * Standard timeout values are used so far
+	 */
+
+	return 0;
+
+out_release:
+	release_locality(chip, 0, 1);
+
+out_err:
+	return rc;
+}
+
+void tpm_vendor_cleanup(struct tpm_chip *chip)
+{
+	release_locality(chip, chip->vendor.locality, 1);
+}
