drivers/tpm/tpm_tis_st33zp24_i2c.c - filogic/uboot - Gitiles

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * STMicroelectronics TPM ST33ZP24 I2C UBOOT driver
  *
  * Copyright (C) 2016, STMicroelectronics - All Rights Reserved
  * Author(s): Christophe Ricard <christophe-h.ricard@st.com> for STMicroelectronics.
  *
  * Description: Device driver for ST33ZP24 I2C TPM TCG.
  *
  * This device driver implements the TPM interface as defined in
  * the TCG TPM Interface Spec version 1.21, revision 1.0 and the
  * STMicroelectronics Protocol Stack Specification version 1.2.0.
  */

 #include <dm.h>
 #include <fdtdec.h>
 #include <i2c.h>
 #include <log.h>
 #include <tpm-v1.h>
 #include <errno.h>
 #include <linux/delay.h>
 #include <linux/types.h>
 #include <asm/unaligned.h>

 #include "tpm_tis.h"
 #include "tpm_internal.h"

 #define TPM_ACCESS			0x0
 #define TPM_STS				0x18
 #define TPM_DATA_FIFO			0x24

 #define LOCALITY0			0

 #define TPM_DUMMY_BYTE			0xAA
 #define TPM_ST33ZP24_I2C_SLAVE_ADDR	0x13

 #define TPM_WRITE_DIRECTION             0x80

 /*
  * st33zp24_i2c_write8_reg
  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  * @param: tpm_register, the tpm tis register where the data should be written
  * @param: tpm_data, the tpm_data to write inside the tpm_register
  * @param: tpm_size, The length of the data
  * @return: Number of byte written successfully else an error code.
  */
 static int st33zp24_i2c_write8_reg(struct udevice *dev, u8 tpm_register,
 				   const u8 *tpm_data, size_t tpm_size)
 {
 	struct tpm_chip_priv *chip_priv = dev_get_uclass_priv(dev);

 	chip_priv->buf[0] = tpm_register;
 	memcpy(chip_priv->buf + 1, tpm_data, tpm_size);

 	return dm_i2c_write(dev, 0, chip_priv->buf, tpm_size + 1);
 }

 /*
 * st33zp24_i2c_read8_reg
 * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
 * @param: tpm_register, the tpm tis register where the data should be read
 * @param: tpm_data, the TPM response
 * @param: tpm_size, tpm TPM response size to read.
 * @return: Number of byte read successfully else an error code.
 */
 static int st33zp24_i2c_read8_reg(struct udevice *dev, u8 tpm_register,
 				  u8 *tpm_data, size_t tpm_size)
 {
 	int status;
 	u8 data;

 	data = TPM_DUMMY_BYTE;
 	status = st33zp24_i2c_write8_reg(dev, tpm_register, &data, 1);
 	if (status < 0)
 		return status;

 	return dm_i2c_read(dev, 0, tpm_data, tpm_size);
 }

 /*
  * st33zp24_i2c_write
  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  * @param: phy_id, the phy description
  * @param: tpm_register, the tpm tis register where the data should be written
  * @param: tpm_data, the tpm_data to write inside the tpm_register
  * @param: tpm_size, the length of the data
  * @return: number of byte written successfully: should be one if success.
  */
 static int st33zp24_i2c_write(struct udevice *dev, u8 tpm_register,
 			      const u8 *tpm_data, size_t tpm_size)
 {
 	return st33zp24_i2c_write8_reg(dev, tpm_register | TPM_WRITE_DIRECTION,
 				       tpm_data, tpm_size);
 }

 /*
  * st33zp24_i2c_read
  * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
  * @param: phy_id, the phy description
  * @param: tpm_register, the tpm tis register where the data should be read
  * @param: tpm_data, the TPM response
  * @param: tpm_size, tpm TPM response size to read.
  * @return: number of byte read successfully: should be one if success.
  */
 static int st33zp24_i2c_read(struct udevice *dev, u8 tpm_register,
 			     u8 *tpm_data, size_t tpm_size)
 {
 	return st33zp24_i2c_read8_reg(dev, tpm_register, tpm_data, tpm_size);
 }

 /*
  * st33zp24_i2c_release_locality release the active locality
  * @param: chip, the tpm chip description.
  */
 static void st33zp24_i2c_release_locality(struct udevice *dev)
 {
 	u8 data = TPM_ACCESS_ACTIVE_LOCALITY;

 	st33zp24_i2c_write(dev, TPM_ACCESS, &data, 1);
 }

 /*
  * st33zp24_i2c_check_locality if the locality is active
  * @param: chip, the tpm chip description
  * @return: the active locality or -EACCES.
  */
 static int st33zp24_i2c_check_locality(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	u8 data;
 	u8 status;

 	status = st33zp24_i2c_read(dev, TPM_ACCESS, &data, 1);
 	if (!status && (data &
 		(TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
 		(TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID))
 		return chip->locality;

 	return -EACCES;
 }

 /*
  * st33zp24_i2c_request_locality request the TPM locality
  * @param: chip, the chip description
  * @return: the active locality or negative value.
  */
 static int st33zp24_i2c_request_locality(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	unsigned long start, stop;
 	long ret;
 	u8 data;

 	if (st33zp24_i2c_check_locality(dev) == chip->locality)
 		return chip->locality;

 	data = TPM_ACCESS_REQUEST_USE;
 	ret = st33zp24_i2c_write(dev, TPM_ACCESS, &data, 1);
 	if (ret < 0)
 		return ret;

 	/* wait for locality activated */
 	start = get_timer(0);
 	stop = chip->timeout_a;
 	do {
 		if (st33zp24_i2c_check_locality(dev) >= 0)
 			return chip->locality;
 		udelay(TPM_TIMEOUT_MS * 1000);
 	} while	 (get_timer(start) < stop);

 	return -EACCES;
 }

 /*
  * st33zp24_i2c_status return the TPM_STS register
  * @param: chip, the tpm chip description
  * @return: the TPM_STS register value.
  */
 static u8 st33zp24_i2c_status(struct udevice *dev)
 {
 	u8 data;

 	st33zp24_i2c_read(dev, TPM_STS, &data, 1);

 	return data;
 }

 /*
  * st33zp24_i2c_get_burstcount return the burstcount address 0x19 0x1A
  * @param: chip, the chip description
  * return: the burstcount or -TPM_DRIVER_ERR in case of error.
  */
 static int st33zp24_i2c_get_burstcount(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	unsigned long start, stop;
 	int burstcnt, status;
 	u8 tpm_reg, temp;

 	/* wait for burstcount */
 	start = get_timer(0);
 	stop = chip->timeout_d;
 	do {
 		tpm_reg = TPM_STS + 1;
 		status = st33zp24_i2c_read(dev, tpm_reg, &temp, 1);
 		if (status < 0)
 			return -EBUSY;

 		tpm_reg = TPM_STS + 2;
 		burstcnt = temp;
 		status = st33zp24_i2c_read(dev, tpm_reg, &temp, 1);
 		if (status < 0)
 			return -EBUSY;

 		burstcnt |= temp << 8;
 		if (burstcnt)
 			return burstcnt;
 		udelay(TIS_SHORT_TIMEOUT_MS * 1000);
 	} while (get_timer(start) < stop);

 	return -EBUSY;
 }

 /*
  * st33zp24_i2c_cancel, cancel the current command execution or
  * set STS to COMMAND READY.
  * @param: chip, tpm_chip description.
  */
 static void st33zp24_i2c_cancel(struct udevice *dev)
 {
 	u8 data;

 	data = TPM_STS_COMMAND_READY;
 	st33zp24_i2c_write(dev, TPM_STS, &data, 1);
 }

 /*
  * st33zp24_i2c_wait_for_stat wait for a TPM_STS value
  * @param: chip, the tpm chip description
  * @param: mask, the value mask to wait
  * @param: timeout, the timeout
  * @param: status,
  * @return: the tpm status, 0 if success, -ETIME if timeout is reached.
  */
 static int st33zp24_i2c_wait_for_stat(struct udevice *dev, u8 mask,
 				      unsigned long timeout, int *status)
 {
 	unsigned long start, stop;

 	/* Check current status */
 	*status = st33zp24_i2c_status(dev);
 	if ((*status & mask) == mask)
 		return 0;

 	start = get_timer(0);
 	stop = timeout;
 	do {
 		udelay(TPM_TIMEOUT_MS * 1000);
 		*status = st33zp24_i2c_status(dev);
 		if ((*status & mask) == mask)
 			return 0;
 	} while (get_timer(start) < stop);

 	return -ETIME;
 }

 /*
  * st33zp24_i2c_recv_data receive data
  * @param: chip, the tpm chip description
  * @param: buf, the buffer where the data are received
  * @param: count, the number of data to receive
  * @return: the number of bytes read from TPM FIFO.
  */
 static int st33zp24_i2c_recv_data(struct udevice *dev, u8 *buf, size_t count)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	int size = 0, burstcnt, len, ret, status;

 	while (size < count &&
 	       st33zp24_i2c_wait_for_stat(dev, TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 				chip->timeout_c, &status) == 0) {
 		burstcnt = st33zp24_i2c_get_burstcount(dev);
 		if (burstcnt < 0)
 			return burstcnt;
 		len = min_t(int, burstcnt, count - size);
 		ret = st33zp24_i2c_read(dev, TPM_DATA_FIFO, buf + size, len);
 		if (ret < 0)
 			return ret;

 		size += len;
 	}

 	return size;
 }

 /*
  * st33zp24_i2c_recv received TPM response through TPM phy.
  * @param: chip, tpm_chip description.
  * @param: buf,	the buffer to store data.
  * @param: count, the number of bytes that can received (sizeof buf).
  * @return: Returns zero in case of success else -EIO.
  */
 static int st33zp24_i2c_recv(struct udevice *dev, u8 *buf, size_t count)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	int size;
 	unsigned int expected;

 	if (!chip)
 		return -ENODEV;

 	if (count < TPM_HEADER_SIZE) {
 		size = -EIO;
 		goto out;
 	}

 	size = st33zp24_i2c_recv_data(dev, buf, TPM_HEADER_SIZE);
 	if (size < TPM_HEADER_SIZE) {
 		debug("TPM error, unable to read header\n");
 		goto out;
 	}

 	expected = get_unaligned_be32(buf + 2);
 	if (expected > count || expected < TPM_HEADER_SIZE) {
 		size = -EIO;
 		goto out;
 	}

 	size += st33zp24_i2c_recv_data(dev, &buf[TPM_HEADER_SIZE],
 				   expected - TPM_HEADER_SIZE);
 	if (size < expected) {
 		debug("TPM error, unable to read remaining bytes of result\n");
 		size = -EIO;
 		goto out;
 	}

 out:
 	st33zp24_i2c_cancel(dev);
 	st33zp24_i2c_release_locality(dev);

 	return size;
 }

 /*
  * st33zp24_i2c_send send TPM commands through TPM phy.
  * @param: chip, tpm_chip description.
  * @param: buf,	the buffer to send.
  * @param: len, the number of bytes to send.
  * @return: Returns zero in case of success else the negative error code.
  */
 static int st33zp24_i2c_send(struct udevice *dev, const u8 *buf, size_t len)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	u32 i, size;
 	int burstcnt, ret, status;
 	u8 data, tpm_stat;

 	if (!chip)
 		return -ENODEV;
 	if (len < TPM_HEADER_SIZE)
 		return -EIO;

 	ret = st33zp24_i2c_request_locality(dev);
 	if (ret < 0)
 		return ret;

 	tpm_stat = st33zp24_i2c_status(dev);
 	if ((tpm_stat & TPM_STS_COMMAND_READY) == 0) {
 		st33zp24_i2c_cancel(dev);
 		if (st33zp24_i2c_wait_for_stat(dev, TPM_STS_COMMAND_READY,
 					       chip->timeout_b, &status) < 0) {
 			ret = -ETIME;
 			goto out_err;
 		}
 	}

 	for (i = 0; i < len - 1;) {
 		burstcnt = st33zp24_i2c_get_burstcount(dev);
 		if (burstcnt < 0)
 			return burstcnt;

 		size = min_t(int, len - i - 1, burstcnt);
 		ret = st33zp24_i2c_write(dev, TPM_DATA_FIFO, buf + i, size);
 		if (ret < 0)
 			goto out_err;

 		i += size;
 	}

 	tpm_stat = st33zp24_i2c_status(dev);
 	if ((tpm_stat & TPM_STS_DATA_EXPECT) == 0) {
 		ret = -EIO;
 		goto out_err;
 	}

 	ret = st33zp24_i2c_write(dev, TPM_DATA_FIFO, buf + len - 1, 1);
 	if (ret < 0)
 		goto out_err;

 	tpm_stat = st33zp24_i2c_status(dev);
 	if ((tpm_stat & TPM_STS_DATA_EXPECT) != 0) {
 		ret = -EIO;
 		goto out_err;
 	}

 	data = TPM_STS_GO;
 	ret = st33zp24_i2c_write(dev, TPM_STS, &data, 1);
 	if (ret < 0)
 		goto out_err;

 	return len;

 out_err:
 	st33zp24_i2c_cancel(dev);
 	st33zp24_i2c_release_locality(dev);

 	return ret;
 }

 static int st33zp24_i2c_cleanup(struct udevice *dev)
 {
 	st33zp24_i2c_cancel(dev);
 	/*
 	 * The TPM needs some time to clean up here,
 	 * so we sleep rather than keeping the bus busy
 	 */
 	mdelay(2);
 	st33zp24_i2c_release_locality(dev);

 	return 0;
 }

 static int st33zp24_i2c_init(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);

 	chip->is_open = 1;

 	/* Default timeouts - these could move to the device tree */
 	chip->timeout_a = TIS_SHORT_TIMEOUT_MS;
 	chip->timeout_b = TIS_LONG_TIMEOUT_MS;
 	chip->timeout_c = TIS_SHORT_TIMEOUT_MS;
 	chip->timeout_d = TIS_SHORT_TIMEOUT_MS;

 	chip->locality = LOCALITY0;

 	/*
 	 * A timeout query to TPM can be placed here.
 	 * Standard timeout values are used so far
 	 */

 	return 0;
 }

 static int st33zp24_i2c_open(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	int rc;

 	debug("%s: start\n", __func__);
 	if (chip->is_open)
 		return -EBUSY;

 	rc = st33zp24_i2c_init(dev);
 	if (rc < 0)
 		chip->is_open = 0;

 	return rc;
 }

 static int st33zp24_i2c_close(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);

 	if (chip->is_open) {
 		st33zp24_i2c_release_locality(dev);
 		chip->is_open = 0;
 		chip->vend_dev = 0;
 	}

 	return 0;
 }

 static int st33zp24_i2c_get_desc(struct udevice *dev, char *buf, int size)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);

 	if (size < 50)
 		return -ENOSPC;

 	return snprintf(buf, size, "1.2 TPM (%s, chip type %s device-id 0x%x)",
 			chip->is_open ? "open" : "closed",
 			dev->name,
 			chip->vend_dev >> 16);
 }

 static const struct tpm_ops st33zp24_i2c_tpm_ops = {
 	.open = st33zp24_i2c_open,
 	.close = st33zp24_i2c_close,
 	.recv = st33zp24_i2c_recv,
 	.send = st33zp24_i2c_send,
 	.cleanup = st33zp24_i2c_cleanup,
 	.get_desc = st33zp24_i2c_get_desc,
 };

 static int st33zp24_i2c_probe(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);

 	/* Default timeouts */
 	chip->timeout_a = TIS_SHORT_TIMEOUT_MS;
 	chip->timeout_b = TIS_LONG_TIMEOUT_MS;
 	chip->timeout_c = TIS_SHORT_TIMEOUT_MS;
 	chip->timeout_d = TIS_SHORT_TIMEOUT_MS;

 	chip->locality = LOCALITY0;

 	i2c_set_chip_offset_len(dev, 0);

 	debug("ST33ZP24 I2C TPM from STMicroelectronics found\n");

 	return 0;
 }

 static int st33zp24_i2c_remove(struct udevice *dev)
 {
 	st33zp24_i2c_release_locality(dev);

 	return 0;
 }

 static const struct udevice_id st33zp24_i2c_ids[] = {
 	{ .compatible = "st,st33zp24-i2c" },
 	{ }
 };

 U_BOOT_DRIVER(st33zp24_i2c) = {
 	.name   = "st33zp24-i2c",
 	.id     = UCLASS_TPM,
 	.of_match = of_match_ptr(st33zp24_i2c_ids),
 	.probe  = st33zp24_i2c_probe,
 	.remove = st33zp24_i2c_remove,
 	.ops = &st33zp24_i2c_tpm_ops,
 	.priv_auto	= sizeof(struct tpm_chip),
 };
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* STMicroelectronics TPM ST33ZP24 I2C UBOOT driver
	*
	* Copyright (C) 2016, STMicroelectronics - All Rights Reserved
	* Author(s): Christophe Ricard <christophe-h.ricard@st.com> for STMicroelectronics.
	*
	* Description: Device driver for ST33ZP24 I2C TPM TCG.
	*
	* This device driver implements the TPM interface as defined in
	* the TCG TPM Interface Spec version 1.21, revision 1.0 and the
	* STMicroelectronics Protocol Stack Specification version 1.2.0.
	*/

	#include <dm.h>
	#include <fdtdec.h>
	#include <i2c.h>
	#include <log.h>
	#include <tpm-v1.h>
	#include <errno.h>
	#include <linux/delay.h>
	#include <linux/types.h>
	#include <asm/unaligned.h>

	#include "tpm_tis.h"
	#include "tpm_internal.h"

	#define TPM_ACCESS 0x0
	#define TPM_STS 0x18
	#define TPM_DATA_FIFO 0x24

	#define LOCALITY0 0

	#define TPM_DUMMY_BYTE 0xAA
	#define TPM_ST33ZP24_I2C_SLAVE_ADDR 0x13

	#define TPM_WRITE_DIRECTION 0x80

	/*
	* st33zp24_i2c_write8_reg
	* Send byte to the TIS register according to the ST33ZP24 I2C protocol.
	* @param: tpm_register, the tpm tis register where the data should be written
	* @param: tpm_data, the tpm_data to write inside the tpm_register
	* @param: tpm_size, The length of the data
	* @return: Number of byte written successfully else an error code.
	*/
	static int st33zp24_i2c_write8_reg(struct udevice *dev, u8 tpm_register,
	const u8 *tpm_data, size_t tpm_size)
	{
	struct tpm_chip_priv *chip_priv = dev_get_uclass_priv(dev);

	chip_priv->buf[0] = tpm_register;
	memcpy(chip_priv->buf + 1, tpm_data, tpm_size);

	return dm_i2c_write(dev, 0, chip_priv->buf, tpm_size + 1);
	}

	/*
	* st33zp24_i2c_read8_reg
	* Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
	* @param: tpm_register, the tpm tis register where the data should be read
	* @param: tpm_data, the TPM response
	* @param: tpm_size, tpm TPM response size to read.
	* @return: Number of byte read successfully else an error code.
	*/
	static int st33zp24_i2c_read8_reg(struct udevice *dev, u8 tpm_register,
	u8 *tpm_data, size_t tpm_size)
	{
	int status;
	u8 data;

	data = TPM_DUMMY_BYTE;
	status = st33zp24_i2c_write8_reg(dev, tpm_register, &data, 1);
	if (status < 0)
	return status;

	return dm_i2c_read(dev, 0, tpm_data, tpm_size);
	}

	/*
	* st33zp24_i2c_write
	* Send byte to the TIS register according to the ST33ZP24 I2C protocol.
	* @param: phy_id, the phy description
	* @param: tpm_register, the tpm tis register where the data should be written
	* @param: tpm_data, the tpm_data to write inside the tpm_register
	* @param: tpm_size, the length of the data
	* @return: number of byte written successfully: should be one if success.
	*/
	static int st33zp24_i2c_write(struct udevice *dev, u8 tpm_register,
	const u8 *tpm_data, size_t tpm_size)
	{
	return st33zp24_i2c_write8_reg(dev, tpm_register \| TPM_WRITE_DIRECTION,
	tpm_data, tpm_size);
	}

	/*
	* st33zp24_i2c_read
	* Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
	* @param: phy_id, the phy description
	* @param: tpm_register, the tpm tis register where the data should be read
	* @param: tpm_data, the TPM response
	* @param: tpm_size, tpm TPM response size to read.
	* @return: number of byte read successfully: should be one if success.
	*/
	static int st33zp24_i2c_read(struct udevice *dev, u8 tpm_register,
	u8 *tpm_data, size_t tpm_size)
	{
	return st33zp24_i2c_read8_reg(dev, tpm_register, tpm_data, tpm_size);
	}

	/*
	* st33zp24_i2c_release_locality release the active locality
	* @param: chip, the tpm chip description.
	*/
	static void st33zp24_i2c_release_locality(struct udevice *dev)
	{
	u8 data = TPM_ACCESS_ACTIVE_LOCALITY;

	st33zp24_i2c_write(dev, TPM_ACCESS, &data, 1);
	}

	/*
	* st33zp24_i2c_check_locality if the locality is active
	* @param: chip, the tpm chip description
	* @return: the active locality or -EACCES.
	*/
	static int st33zp24_i2c_check_locality(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	u8 data;
	u8 status;

	status = st33zp24_i2c_read(dev, TPM_ACCESS, &data, 1);
	if (!status && (data &
	(TPM_ACCESS_ACTIVE_LOCALITY \| TPM_ACCESS_VALID)) ==
	(TPM_ACCESS_ACTIVE_LOCALITY \| TPM_ACCESS_VALID))
	return chip->locality;

	return -EACCES;
	}

	/*
	* st33zp24_i2c_request_locality request the TPM locality
	* @param: chip, the chip description
	* @return: the active locality or negative value.
	*/
	static int st33zp24_i2c_request_locality(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	unsigned long start, stop;
	long ret;
	u8 data;

	if (st33zp24_i2c_check_locality(dev) == chip->locality)
	return chip->locality;

	data = TPM_ACCESS_REQUEST_USE;
	ret = st33zp24_i2c_write(dev, TPM_ACCESS, &data, 1);
	if (ret < 0)
	return ret;

	/* wait for locality activated */
	start = get_timer(0);
	stop = chip->timeout_a;
	do {
	if (st33zp24_i2c_check_locality(dev) >= 0)
	return chip->locality;
	udelay(TPM_TIMEOUT_MS * 1000);
	} while (get_timer(start) < stop);

	return -EACCES;
	}

	/*
	* st33zp24_i2c_status return the TPM_STS register
	* @param: chip, the tpm chip description
	* @return: the TPM_STS register value.
	*/
	static u8 st33zp24_i2c_status(struct udevice *dev)
	{
	u8 data;

	st33zp24_i2c_read(dev, TPM_STS, &data, 1);

	return data;
	}

	/*
	* st33zp24_i2c_get_burstcount return the burstcount address 0x19 0x1A
	* @param: chip, the chip description
	* return: the burstcount or -TPM_DRIVER_ERR in case of error.
	*/
	static int st33zp24_i2c_get_burstcount(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	unsigned long start, stop;
	int burstcnt, status;
	u8 tpm_reg, temp;

	/* wait for burstcount */
	start = get_timer(0);
	stop = chip->timeout_d;
	do {
	tpm_reg = TPM_STS + 1;
	status = st33zp24_i2c_read(dev, tpm_reg, &temp, 1);
	if (status < 0)
	return -EBUSY;

	tpm_reg = TPM_STS + 2;
	burstcnt = temp;
	status = st33zp24_i2c_read(dev, tpm_reg, &temp, 1);
	if (status < 0)
	return -EBUSY;

	burstcnt \|= temp << 8;
	if (burstcnt)
	return burstcnt;
	udelay(TIS_SHORT_TIMEOUT_MS * 1000);
	} while (get_timer(start) < stop);

	return -EBUSY;
	}

	/*
	* st33zp24_i2c_cancel, cancel the current command execution or
	* set STS to COMMAND READY.
	* @param: chip, tpm_chip description.
	*/
	static void st33zp24_i2c_cancel(struct udevice *dev)
	{
	u8 data;

	data = TPM_STS_COMMAND_READY;
	st33zp24_i2c_write(dev, TPM_STS, &data, 1);
	}

	/*
	* st33zp24_i2c_wait_for_stat wait for a TPM_STS value
	* @param: chip, the tpm chip description
	* @param: mask, the value mask to wait
	* @param: timeout, the timeout
	* @param: status,
	* @return: the tpm status, 0 if success, -ETIME if timeout is reached.
	*/
	static int st33zp24_i2c_wait_for_stat(struct udevice *dev, u8 mask,
	unsigned long timeout, int *status)
	{
	unsigned long start, stop;

	/* Check current status */
	*status = st33zp24_i2c_status(dev);
	if ((*status & mask) == mask)
	return 0;

	start = get_timer(0);
	stop = timeout;
	do {
	udelay(TPM_TIMEOUT_MS * 1000);
	*status = st33zp24_i2c_status(dev);
	if ((*status & mask) == mask)
	return 0;
	} while (get_timer(start) < stop);

	return -ETIME;
	}

	/*
	* st33zp24_i2c_recv_data receive data
	* @param: chip, the tpm chip description
	* @param: buf, the buffer where the data are received
	* @param: count, the number of data to receive
	* @return: the number of bytes read from TPM FIFO.
	*/
	static int st33zp24_i2c_recv_data(struct udevice dev, u8 buf, size_t count)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	int size = 0, burstcnt, len, ret, status;

	while (size < count &&
	st33zp24_i2c_wait_for_stat(dev, TPM_STS_DATA_AVAIL \| TPM_STS_VALID,
	chip->timeout_c, &status) == 0) {
	burstcnt = st33zp24_i2c_get_burstcount(dev);
	if (burstcnt < 0)
	return burstcnt;
	len = min_t(int, burstcnt, count - size);
	ret = st33zp24_i2c_read(dev, TPM_DATA_FIFO, buf + size, len);
	if (ret < 0)
	return ret;

	size += len;
	}

	return size;
	}

	/*
	* st33zp24_i2c_recv received TPM response through TPM phy.
	* @param: chip, tpm_chip description.
	* @param: buf, the buffer to store data.
	* @param: count, the number of bytes that can received (sizeof buf).
	* @return: Returns zero in case of success else -EIO.
	*/
	static int st33zp24_i2c_recv(struct udevice dev, u8 buf, size_t count)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	int size;
	unsigned int expected;

	if (!chip)
	return -ENODEV;

	if (count < TPM_HEADER_SIZE) {
	size = -EIO;
	goto out;
	}

	size = st33zp24_i2c_recv_data(dev, buf, TPM_HEADER_SIZE);
	if (size < TPM_HEADER_SIZE) {
	debug("TPM error, unable to read header\n");
	goto out;
	}

	expected = get_unaligned_be32(buf + 2);
	if (expected > count \|\| expected < TPM_HEADER_SIZE) {
	size = -EIO;
	goto out;
	}

	size += st33zp24_i2c_recv_data(dev, &buf[TPM_HEADER_SIZE],
	expected - TPM_HEADER_SIZE);
	if (size < expected) {
	debug("TPM error, unable to read remaining bytes of result\n");
	size = -EIO;
	goto out;
	}

	out:
	st33zp24_i2c_cancel(dev);
	st33zp24_i2c_release_locality(dev);

	return size;
	}

	/*
	* st33zp24_i2c_send send TPM commands through TPM phy.
	* @param: chip, tpm_chip description.
	* @param: buf, the buffer to send.
	* @param: len, the number of bytes to send.
	* @return: Returns zero in case of success else the negative error code.
	*/
	static int st33zp24_i2c_send(struct udevice dev, const u8 buf, size_t len)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	u32 i, size;
	int burstcnt, ret, status;
	u8 data, tpm_stat;

	if (!chip)
	return -ENODEV;
	if (len < TPM_HEADER_SIZE)
	return -EIO;

	ret = st33zp24_i2c_request_locality(dev);
	if (ret < 0)
	return ret;

	tpm_stat = st33zp24_i2c_status(dev);
	if ((tpm_stat & TPM_STS_COMMAND_READY) == 0) {
	st33zp24_i2c_cancel(dev);
	if (st33zp24_i2c_wait_for_stat(dev, TPM_STS_COMMAND_READY,
	chip->timeout_b, &status) < 0) {
	ret = -ETIME;
	goto out_err;
	}
	}

	for (i = 0; i < len - 1;) {
	burstcnt = st33zp24_i2c_get_burstcount(dev);
	if (burstcnt < 0)
	return burstcnt;

	size = min_t(int, len - i - 1, burstcnt);
	ret = st33zp24_i2c_write(dev, TPM_DATA_FIFO, buf + i, size);
	if (ret < 0)
	goto out_err;

	i += size;
	}

	tpm_stat = st33zp24_i2c_status(dev);
	if ((tpm_stat & TPM_STS_DATA_EXPECT) == 0) {
	ret = -EIO;
	goto out_err;
	}

	ret = st33zp24_i2c_write(dev, TPM_DATA_FIFO, buf + len - 1, 1);
	if (ret < 0)
	goto out_err;

	tpm_stat = st33zp24_i2c_status(dev);
	if ((tpm_stat & TPM_STS_DATA_EXPECT) != 0) {
	ret = -EIO;
	goto out_err;
	}

	data = TPM_STS_GO;
	ret = st33zp24_i2c_write(dev, TPM_STS, &data, 1);
	if (ret < 0)
	goto out_err;

	return len;

	out_err:
	st33zp24_i2c_cancel(dev);
	st33zp24_i2c_release_locality(dev);

	return ret;
	}

	static int st33zp24_i2c_cleanup(struct udevice *dev)
	{
	st33zp24_i2c_cancel(dev);
	/*
	* The TPM needs some time to clean up here,
	* so we sleep rather than keeping the bus busy
	*/
	mdelay(2);
	st33zp24_i2c_release_locality(dev);

	return 0;
	}

	static int st33zp24_i2c_init(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);

	chip->is_open = 1;

	/* Default timeouts - these could move to the device tree */
	chip->timeout_a = TIS_SHORT_TIMEOUT_MS;
	chip->timeout_b = TIS_LONG_TIMEOUT_MS;
	chip->timeout_c = TIS_SHORT_TIMEOUT_MS;
	chip->timeout_d = TIS_SHORT_TIMEOUT_MS;

	chip->locality = LOCALITY0;

	/*
	* A timeout query to TPM can be placed here.
	* Standard timeout values are used so far
	*/

	return 0;
	}

	static int st33zp24_i2c_open(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	int rc;

	debug("%s: start\n", __func__);
	if (chip->is_open)
	return -EBUSY;

	rc = st33zp24_i2c_init(dev);
	if (rc < 0)
	chip->is_open = 0;

	return rc;
	}

	static int st33zp24_i2c_close(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);

	if (chip->is_open) {
	st33zp24_i2c_release_locality(dev);
	chip->is_open = 0;
	chip->vend_dev = 0;
	}

	return 0;
	}

	static int st33zp24_i2c_get_desc(struct udevice dev, char buf, int size)
	{
	struct tpm_chip *chip = dev_get_priv(dev);

	if (size < 50)
	return -ENOSPC;

	return snprintf(buf, size, "1.2 TPM (%s, chip type %s device-id 0x%x)",
	chip->is_open ? "open" : "closed",
	dev->name,
	chip->vend_dev >> 16);
	}

	static const struct tpm_ops st33zp24_i2c_tpm_ops = {
	.open = st33zp24_i2c_open,
	.close = st33zp24_i2c_close,
	.recv = st33zp24_i2c_recv,
	.send = st33zp24_i2c_send,
	.cleanup = st33zp24_i2c_cleanup,
	.get_desc = st33zp24_i2c_get_desc,
	};

	static int st33zp24_i2c_probe(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);

	/* Default timeouts */
	chip->timeout_a = TIS_SHORT_TIMEOUT_MS;
	chip->timeout_b = TIS_LONG_TIMEOUT_MS;
	chip->timeout_c = TIS_SHORT_TIMEOUT_MS;
	chip->timeout_d = TIS_SHORT_TIMEOUT_MS;

	chip->locality = LOCALITY0;

	i2c_set_chip_offset_len(dev, 0);

	debug("ST33ZP24 I2C TPM from STMicroelectronics found\n");

	return 0;
	}

	static int st33zp24_i2c_remove(struct udevice *dev)
	{
	st33zp24_i2c_release_locality(dev);

	return 0;
	}

	static const struct udevice_id st33zp24_i2c_ids[] = {
	{ .compatible = "st,st33zp24-i2c" },
	{ }
	};

	U_BOOT_DRIVER(st33zp24_i2c) = {
	.name = "st33zp24-i2c",
	.id = UCLASS_TPM,
	.of_match = of_match_ptr(st33zp24_i2c_ids),
	.probe = st33zp24_i2c_probe,
	.remove = st33zp24_i2c_remove,
	.ops = &st33zp24_i2c_tpm_ops,
	.priv_auto = sizeof(struct tpm_chip),
	};