drivers/tpm/tpm_tis_i2c.c - platform/external/u-boot - Gitiles

 /*
  * 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 <fdtdec.h>
 #include <linux/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"

 DECLARE_GLOBAL_DATA_PTR;

 /* Address of the TPM on the I2C bus */
 #define TPM_I2C_ADDR		0x20

 /* 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,	/* ms */
 };

 /* expected value for DIDVID register */
 #define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
 #define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L

 enum i2c_chip_type {
 	SLB9635,
 	SLB9645,
 	UNKNOWN,
 };

 static const char * const chip_name[] = {
 	[SLB9635] = "slb9635tt",
 	[SLB9645] = "slb9645tt",
 	[UNKNOWN] = "unknown/fallback to slb9635",
 };

 #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 */
 	enum i2c_chip_type chip_type;
 };

 static struct tpm_dev tpm_dev = {
 	.addr = TPM_I2C_ADDR
 };

 static struct tpm_dev tpm_dev;

 /*
  * 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;

 	if ((tpm_dev.chip_type == SLB9635) || (tpm_dev.chip_type == UNKNOWN)) {
 		/* slb9635 protocol should work in both cases */
 		for (count = 0; count < MAX_COUNT; count++) {
 			rc = i2c_write(tpm_dev.addr, 0, 0,
 				       (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 = i2c_read(tpm_dev.addr, 0, 0, buffer, len);
 			if (rc == 0)
 				break;  /* success, break to skip sleep */
 		}
 	} else {
 		/*
 		 * Use a combined read for newer chips.
 		 * Unfortunately the smbus functions are not suitable due to
 		 * the 32 byte limit of the smbus.
 		 * Retries should usually not be needed, but are kept just to
 		 * be safe on the safe side.
 		 */
 		for (count = 0; count < MAX_COUNT; count++) {
 			rc = i2c_read(tpm_dev.addr, addr, 1, buffer, len);
 			if (rc == 0)
 				break;  /* break here to skip sleep */
 			udelay(SLEEP_DURATION);
 		}
 	}

 	/* Take care of 'guard time' */
 	udelay(SLEEP_DURATION);
 	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 = i2c_write(tpm_dev.addr, 0, 0, tpm_dev.buf, len + 1);
 		if (rc == 0)
 			break;  /* Success, break to skip sleep */
 		udelay(sleep_time);
 	}

 	/* take care of 'guard time' */
 	udelay(SLEEP_DURATION);
 	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,
 };


 static enum i2c_chip_type tpm_vendor_chip_type(void)
 {
 #ifdef CONFIG_OF_CONTROL
 	const void *blob = gd->fdt_blob;

 	if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9645_TPM) >= 0)
 		return SLB9645;

 	if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9635_TPM) >= 0)
 		return SLB9635;
 #endif
 	return UNKNOWN;
 }

 /* Initialisation of i2c tpm */
 int tpm_vendor_init(uint32_t dev_addr)
 {
 	u32 vendor;
 	u32 expected_did_vid;
 	uint old_addr;
 	int rc = 0;
 	struct tpm_chip *chip;

 	old_addr = tpm_dev.addr;
 	if (dev_addr != 0)
 		tpm_dev.addr = dev_addr;

 	tpm_dev.chip_type = tpm_vendor_chip_type();

 	chip = tpm_register_hardware(&tpm_tis_i2c);
 	if (chip < 0) {
 		rc = -ENODEV;
 		goto out_err;
 	}

 	/* Disable interrupts (not supported) */
 	chip->vendor.irq = 0;

 	/* 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;
 	}

 	if (tpm_dev.chip_type == SLB9635) {
 		vendor = be32_to_cpu(vendor);
 		expected_did_vid = TPM_TIS_I2C_DID_VID_9635;
 	} else {
 		/* device id and byte order has changed for newer i2c tpms */
 		expected_did_vid = TPM_TIS_I2C_DID_VID_9645;
 	}

 	if (tpm_dev.chip_type != UNKNOWN && vendor != expected_did_vid) {
 		error("Vendor id did not match! ID was %08x\n", vendor);
 		rc = -ENODEV;
 		goto out_release;
 	}

 	debug("1.2 TPM (chip type %s device-id 0x%X)\n",
 	      chip_name[tpm_dev.chip_type], 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:
 	tpm_dev.addr = old_addr;
 	return rc;
 }

 void tpm_vendor_cleanup(struct tpm_chip *chip)
 {
 	release_locality(chip, chip->vendor.locality, 1);
 }
	/*
	* 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 <fdtdec.h>
	#include <linux/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"

	DECLARE_GLOBAL_DATA_PTR;

	/* Address of the TPM on the I2C bus */
	#define TPM_I2C_ADDR 0x20

	/* 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, /* ms */
	};

	/* expected value for DIDVID register */
	#define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
	#define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L

	enum i2c_chip_type {
	SLB9635,
	SLB9645,
	UNKNOWN,
	};

	static const char * const chip_name[] = {
	[SLB9635] = "slb9635tt",
	[SLB9645] = "slb9645tt",
	[UNKNOWN] = "unknown/fallback to slb9635",
	};

	#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 */
	enum i2c_chip_type chip_type;
	};

	static struct tpm_dev tpm_dev = {
	.addr = TPM_I2C_ADDR
	};

	static struct tpm_dev tpm_dev;

	/*
	* 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;

	if ((tpm_dev.chip_type == SLB9635) \|\| (tpm_dev.chip_type == UNKNOWN)) {
	/* slb9635 protocol should work in both cases */
	for (count = 0; count < MAX_COUNT; count++) {
	rc = i2c_write(tpm_dev.addr, 0, 0,
	(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 = i2c_read(tpm_dev.addr, 0, 0, buffer, len);
	if (rc == 0)
	break; /* success, break to skip sleep */
	}
	} else {
	/*
	* Use a combined read for newer chips.
	* Unfortunately the smbus functions are not suitable due to
	* the 32 byte limit of the smbus.
	* Retries should usually not be needed, but are kept just to
	* be safe on the safe side.
	*/
	for (count = 0; count < MAX_COUNT; count++) {
	rc = i2c_read(tpm_dev.addr, addr, 1, buffer, len);
	if (rc == 0)
	break; /* break here to skip sleep */
	udelay(SLEEP_DURATION);
	}
	}

	/* Take care of 'guard time' */
	udelay(SLEEP_DURATION);
	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 = i2c_write(tpm_dev.addr, 0, 0, tpm_dev.buf, len + 1);
	if (rc == 0)
	break; /* Success, break to skip sleep */
	udelay(sleep_time);
	}

	/* take care of 'guard time' */
	udelay(SLEEP_DURATION);
	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,
	};


	static enum i2c_chip_type tpm_vendor_chip_type(void)
	{
	#ifdef CONFIG_OF_CONTROL
	const void *blob = gd->fdt_blob;

	if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9645_TPM) >= 0)
	return SLB9645;

	if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9635_TPM) >= 0)
	return SLB9635;
	#endif
	return UNKNOWN;
	}

	/* Initialisation of i2c tpm */
	int tpm_vendor_init(uint32_t dev_addr)
	{
	u32 vendor;
	u32 expected_did_vid;
	uint old_addr;
	int rc = 0;
	struct tpm_chip *chip;

	old_addr = tpm_dev.addr;
	if (dev_addr != 0)
	tpm_dev.addr = dev_addr;

	tpm_dev.chip_type = tpm_vendor_chip_type();

	chip = tpm_register_hardware(&tpm_tis_i2c);
	if (chip < 0) {
	rc = -ENODEV;
	goto out_err;
	}

	/* Disable interrupts (not supported) */
	chip->vendor.irq = 0;

	/* 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;
	}

	if (tpm_dev.chip_type == SLB9635) {
	vendor = be32_to_cpu(vendor);
	expected_did_vid = TPM_TIS_I2C_DID_VID_9635;
	} else {
	/* device id and byte order has changed for newer i2c tpms */
	expected_did_vid = TPM_TIS_I2C_DID_VID_9645;
	}

	if (tpm_dev.chip_type != UNKNOWN && vendor != expected_did_vid) {
	error("Vendor id did not match! ID was %08x\n", vendor);
	rc = -ENODEV;
	goto out_release;
	}

	debug("1.2 TPM (chip type %s device-id 0x%X)\n",
	chip_name[tpm_dev.chip_type], 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:
	tpm_dev.addr = old_addr;
	return rc;
	}

	void tpm_vendor_cleanup(struct tpm_chip *chip)
	{
	release_locality(chip, chip->vendor.locality, 1);
	}