drivers/tpm/tpm_tis_st33zp24_spi.c - github/trini/u-boot - Gitiles

 /*
  * STMicroelectronics TPM ST33ZP24 SPI UBOOT driver
  *
  * Copyright (C) 2016 STMicroelectronics
  *
  * Description: Device driver for ST33ZP24 SPI 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.
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */

 #include <common.h>
 #include <dm.h>
 #include <fdtdec.h>
 #include <spi.h>
 #include <tpm.h>
 #include <errno.h>
 #include <linux/types.h>
 #include <asm/unaligned.h>
 #include <linux/compat.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_DATA_FIFO				0x24
 #define TPM_INTF_CAPABILITY			0x14

 #define TPM_DUMMY_BYTE				0x00
 #define TPM_WRITE_DIRECTION			0x80

 #define MAX_SPI_LATENCY				15
 #define LOCALITY0				0

 #define ST33ZP24_OK					0x5A
 #define ST33ZP24_UNDEFINED_ERR				0x80
 #define ST33ZP24_BADLOCALITY				0x81
 #define ST33ZP24_TISREGISTER_UKNOWN			0x82
 #define ST33ZP24_LOCALITY_NOT_ACTIVATED			0x83
 #define ST33ZP24_HASH_END_BEFORE_HASH_START		0x84
 #define ST33ZP24_BAD_COMMAND_ORDER			0x85
 #define ST33ZP24_INCORECT_RECEIVED_LENGTH		0x86
 #define ST33ZP24_TPM_FIFO_OVERFLOW			0x89
 #define ST33ZP24_UNEXPECTED_READ_FIFO			0x8A
 #define ST33ZP24_UNEXPECTED_WRITE_FIFO			0x8B
 #define ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END	0x90
 #define ST33ZP24_DUMMY_BYTES				0x00

 /*
  * TPM command can be up to 2048 byte, A TPM response can be up to
  * 1024 byte.
  * Between command and response, there are latency byte (up to 15
  * usually on st33zp24 2 are enough).
  *
  * Overall when sending a command and expecting an answer we need if
  * worst case:
  * 2048 (for the TPM command) + 1024 (for the TPM answer).  We need
  * some latency byte before the answer is available (max 15).
  * We have 2048 + 1024 + 15.
  */
 #define ST33ZP24_SPI_BUFFER_SIZE (TPM_BUFSIZE + (TPM_BUFSIZE / 2) +\
 				  MAX_SPI_LATENCY)

 struct st33zp24_spi_phy {
 	int latency;

 	u8 tx_buf[ST33ZP24_SPI_BUFFER_SIZE];
 	u8 rx_buf[ST33ZP24_SPI_BUFFER_SIZE];
 };

 static int st33zp24_spi_status_to_errno(u8 code)
 {
 	switch (code) {
 	case ST33ZP24_OK:
 		return 0;
 	case ST33ZP24_UNDEFINED_ERR:
 	case ST33ZP24_BADLOCALITY:
 	case ST33ZP24_TISREGISTER_UKNOWN:
 	case ST33ZP24_LOCALITY_NOT_ACTIVATED:
 	case ST33ZP24_HASH_END_BEFORE_HASH_START:
 	case ST33ZP24_BAD_COMMAND_ORDER:
 	case ST33ZP24_UNEXPECTED_READ_FIFO:
 	case ST33ZP24_UNEXPECTED_WRITE_FIFO:
 	case ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END:
 		return -EPROTO;
 	case ST33ZP24_INCORECT_RECEIVED_LENGTH:
 	case ST33ZP24_TPM_FIFO_OVERFLOW:
 		return -EMSGSIZE;
 	case ST33ZP24_DUMMY_BYTES:
 		return -ENOSYS;
 	}
 	return code;
 }

 /*
  * st33zp24_spi_send
  * Send byte to TPM register according to the ST33ZP24 SPI protocol.
  * @param: tpm, the chip 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: should be zero if success else a negative error code.
  */
 static int st33zp24_spi_write(struct udevice *dev, u8 tpm_register,
 			      const u8 *tpm_data, size_t tpm_size)
 {
 	int total_length = 0, ret;
 	struct spi_slave *slave = dev_get_parent_priv(dev);
 	struct st33zp24_spi_phy *phy = dev_get_platdata(dev);

 	u8 *tx_buf = (u8 *)phy->tx_buf;
 	u8 *rx_buf = phy->rx_buf;

 	tx_buf[total_length++] = TPM_WRITE_DIRECTION | LOCALITY0;
 	tx_buf[total_length++] = tpm_register;

 	if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
 		tx_buf[total_length++] = tpm_size >> 8;
 		tx_buf[total_length++] = tpm_size;
 	}
 	memcpy(tx_buf + total_length, tpm_data, tpm_size);
 	total_length += tpm_size;

 	memset(tx_buf + total_length, TPM_DUMMY_BYTE, phy->latency);

 	total_length += phy->latency;

 	ret = spi_claim_bus(slave);
 	if (ret < 0)
 		return ret;

 	ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
 		       SPI_XFER_BEGIN | SPI_XFER_END);
 	if (ret < 0)
 		return ret;

 	spi_release_bus(slave);

 	if (ret == 0)
 		ret = rx_buf[total_length - 1];

 	return st33zp24_spi_status_to_errno(ret);
 }

 /*
  * spi_st33zp24_spi_read8_reg
  * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
  * @param: tpm, the chip description
  * @param: tpm_loc, the locality to read register from
  * @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: should be zero if success else a negative error code.
  */
 static u8 st33zp24_spi_read8_reg(struct udevice *dev, u8 tpm_register,
 				 u8 *tpm_data, size_t tpm_size)
 {
 	int total_length = 0, ret;
 	struct spi_slave *slave = dev_get_parent_priv(dev);
 	struct st33zp24_spi_phy *phy = dev_get_platdata(dev);

 	u8 *tx_buf = (u8 *)phy->tx_buf;
 	u8 *rx_buf = phy->rx_buf;

 	/* Pre-Header */
 	tx_buf[total_length++] = LOCALITY0;
 	tx_buf[total_length++] = tpm_register;

 	memset(&tx_buf[total_length], TPM_DUMMY_BYTE,
 	       phy->latency + tpm_size);
 	total_length += phy->latency + tpm_size;

 	ret = spi_claim_bus(slave);
 	if (ret < 0)
 		return 0;

 	ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
 		       SPI_XFER_BEGIN | SPI_XFER_END);
 	if (ret < 0)
 		return 0;

 	spi_release_bus(slave);

 	if (tpm_size > 0 && ret == 0) {
 		ret = rx_buf[total_length - tpm_size - 1];
 		memcpy(tpm_data, rx_buf + total_length - tpm_size, tpm_size);
 	}
 	return ret;
 }

 /*
  * st33zp24_spi_recv
  * Recv byte from the TIS register according to the ST33ZP24 SPI 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_spi_read(struct udevice *dev, u8 tpm_register,
 			     u8 *tpm_data, size_t tpm_size)
 {
 	int ret;

 	ret = st33zp24_spi_read8_reg(dev, tpm_register, tpm_data, tpm_size);
 	if (!st33zp24_spi_status_to_errno(ret))
 		return tpm_size;

 	return ret;
 }

 static int st33zp24_spi_evaluate_latency(struct udevice *dev)
 {
 	int latency = 1, status = 0;
 	u8 data = 0;
 	struct st33zp24_spi_phy *phy = dev_get_platdata(dev);

 	while (!status && latency < MAX_SPI_LATENCY) {
 		phy->latency = latency;
 		status = st33zp24_spi_read8_reg(dev, TPM_INTF_CAPABILITY,
 						&data, 1);
 		latency++;
 	}
 	if (status < 0)
 		return status;
 	if (latency == MAX_SPI_LATENCY)
 		return -ENODEV;

 	return latency - 1;
 }

 /*
  * st33zp24_spi_release_locality release the active locality
  * @param: chip, the tpm chip description.
  */
 static void st33zp24_spi_release_locality(struct udevice *dev)
 {
 	u8 data = TPM_ACCESS_ACTIVE_LOCALITY;

 	st33zp24_spi_write(dev, TPM_ACCESS, &data, 1);
 }

 /*
  * st33zp24_spi_check_locality if the locality is active
  * @param: chip, the tpm chip description
  * @return: the active locality or -EACCES.
  */
 static int st33zp24_spi_check_locality(struct udevice *dev)
 {
 	u8 data;
 	u8 status;
 	struct tpm_chip *chip = dev_get_priv(dev);

 	status = st33zp24_spi_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_spi_request_locality request the TPM locality
  * @param: chip, the chip description
  * @return: the active locality or negative value.
  */
 static int st33zp24_spi_request_locality(struct udevice *dev)
 {
 	unsigned long start, stop;
 	long ret;
 	u8 data;
 	struct tpm_chip *chip = dev_get_priv(dev);

 	if (st33zp24_spi_check_locality(dev) == chip->locality)
 		return chip->locality;

 	data = TPM_ACCESS_REQUEST_USE;
 	ret = st33zp24_spi_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_spi_check_locality(dev) >= 0)
 			return chip->locality;
 		udelay(TPM_TIMEOUT_MS * 1000);
 	} while	 (get_timer(start) < stop);

 	return -EACCES;
 }

 /*
  * st33zp24_spi_status return the TPM_STS register
  * @param: chip, the tpm chip description
  * @return: the TPM_STS register value.
  */
 static u8 st33zp24_spi_status(struct udevice *dev)
 {
 	u8 data;

 	st33zp24_spi_read(dev, TPM_STS, &data, 1);
 	return data;
 }

 /*
  * st33zp24_spi_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_spi_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_spi_read(dev, tpm_reg, &temp, 1);
 		if (status < 0)
 			return -EBUSY;

 		tpm_reg = TPM_STS + 2;
 		burstcnt = temp;
 		status = st33zp24_spi_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_spi_cancel, cancel the current command execution or
  * set STS to COMMAND READY.
  * @param: chip, tpm_chip description.
  */
 static void st33zp24_spi_cancel(struct udevice *dev)
 {
 	u8 data;

 	data = TPM_STS_COMMAND_READY;
 	st33zp24_spi_write(dev, TPM_STS, &data, 1);
 }

 /*
  * st33zp24_spi_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_spi_wait_for_stat(struct udevice *dev, u8 mask,
 				  unsigned long timeout, int *status)
 {
 	unsigned long start, stop;

 	/* Check current status */
 	*status = st33zp24_spi_status(dev);
 	if ((*status & mask) == mask)
 		return 0;

 	start = get_timer(0);
 	stop = timeout;
 	do {
 		udelay(TPM_TIMEOUT_MS * 1000);
 		*status = st33zp24_spi_status(dev);
 		if ((*status & mask) == mask)
 			return 0;
 	} while (get_timer(start) < stop);

 	return -ETIME;
 }

 /*
  * st33zp24_spi_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_spi_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_spi_wait_for_stat(dev, TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 				chip->timeout_c, &status) == 0) {
 		burstcnt = st33zp24_spi_get_burstcount(dev);
 		if (burstcnt < 0)
 			return burstcnt;
 		len = min_t(int, burstcnt, count - size);
 		ret = st33zp24_spi_read(dev, TPM_DATA_FIFO, buf + size, len);
 		if (ret < 0)
 			return ret;

 		size += len;
 	}
 	return size;
 }

 /*
  * st33zp24_spi_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_spi_recv(struct udevice *dev, u8 *buf, size_t count)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	int size, expected;

 	if (!chip)
 		return -ENODEV;

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

 	size = st33zp24_spi_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) {
 		size = -EIO;
 		goto out;
 	}

 	size += st33zp24_spi_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_spi_cancel(dev);
 	st33zp24_spi_release_locality(dev);

 	return size;
 }

 /*
  * st33zp24_spi_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_spi_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_spi_request_locality(dev);
 	if (ret < 0)
 		return ret;

 	tpm_stat = st33zp24_spi_status(dev);
 	if ((tpm_stat & TPM_STS_COMMAND_READY) == 0) {
 		st33zp24_spi_cancel(dev);
 		if (st33zp24_spi_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_spi_get_burstcount(dev);
 		if (burstcnt < 0)
 			return burstcnt;

 		size = min_t(int, len - i - 1, burstcnt);
 		ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + i, size);
 		if (ret < 0)
 			goto out_err;

 		i += size;
 	}

 	tpm_stat = st33zp24_spi_status(dev);
 	if ((tpm_stat & TPM_STS_DATA_EXPECT) == 0) {
 		ret = -EIO;
 		goto out_err;
 	}

 	ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + len - 1, 1);
 	if (ret < 0)
 		goto out_err;

 	tpm_stat = st33zp24_spi_status(dev);
 	if ((tpm_stat & TPM_STS_DATA_EXPECT) != 0) {
 		ret = -EIO;
 		goto out_err;
 	}

 	data = TPM_STS_GO;
 	ret = st33zp24_spi_write(dev, TPM_STS, &data, 1);
 	if (ret < 0)
 		goto out_err;

 	return len;

 out_err:
 	st33zp24_spi_cancel(dev);
 	st33zp24_spi_release_locality(dev);

 	return ret;
 }

 static int st33zp24_spi_cleanup(struct udevice *dev)
 {
 	st33zp24_spi_cancel(dev);
 	/*
 	 * The TPM needs some time to clean up here,
 	 * so we sleep rather than keeping the bus busy
 	 */
 	mdelay(2);
 	st33zp24_spi_release_locality(dev);

 	return 0;
 }

 static int st33zp24_spi_init(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);
 	struct st33zp24_spi_phy *phy = dev_get_platdata(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;

 	phy->latency = st33zp24_spi_evaluate_latency(dev);
 	if (phy->latency <= 0)
 		return -ENODEV;

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

 	return 0;
 }

 static int st33zp24_spi_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_spi_init(dev);
 	if (rc < 0)
 		chip->is_open = 0;

 	return rc;
 }

 static int st33zp24_spi_close(struct udevice *dev)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);

 	if (chip->is_open) {
 		st33zp24_spi_release_locality(dev);
 		chip->is_open = 0;
 		chip->vend_dev = 0;
 	}

 	return 0;
 }

 static int st33zp24_spi_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);
 }

 const struct tpm_ops st33zp24_spi_tpm_ops = {
 	.open = st33zp24_spi_open,
 	.close = st33zp24_spi_close,
 	.recv = st33zp24_spi_recv,
 	.send = st33zp24_spi_send,
 	.cleanup = st33zp24_spi_cleanup,
 	.get_desc = st33zp24_spi_get_desc,
 };

 static int st33zp24_spi_probe(struct udevice *dev)
 {
 	struct tpm_chip_priv *uc_priv = dev_get_uclass_priv(dev);

 	uc_priv->duration_ms[TPM_SHORT] = TIS_SHORT_TIMEOUT_MS;
 	uc_priv->duration_ms[TPM_MEDIUM] = TIS_LONG_TIMEOUT_MS;
 	uc_priv->duration_ms[TPM_LONG] = TIS_LONG_TIMEOUT_MS;
 	uc_priv->retry_time_ms = TPM_TIMEOUT_MS;

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

 	return 0;
 }

 static int st33zp24_spi_remove(struct udevice *dev)
 {
 	st33zp24_spi_release_locality(dev);

 	return 0;
 }

 static const struct udevice_id st33zp24_spi_ids[] = {
 	{ .compatible = "st,st33zp24-spi" },
 	{ }
 };

 U_BOOT_DRIVER(st33zp24_spi_spi) = {
 	.name   = "st33zp24-spi",
 	.id     = UCLASS_TPM,
 	.of_match = of_match_ptr(st33zp24_spi_ids),
 	.probe  = st33zp24_spi_probe,
 	.remove = st33zp24_spi_remove,
 	.ops = &st33zp24_spi_tpm_ops,
 	.priv_auto_alloc_size = sizeof(struct tpm_chip),
 	.platdata_auto_alloc_size = sizeof(struct st33zp24_spi_phy),
 };
	/*
	* STMicroelectronics TPM ST33ZP24 SPI UBOOT driver
	*
	* Copyright (C) 2016 STMicroelectronics
	*
	* Description: Device driver for ST33ZP24 SPI 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.
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <common.h>
	#include <dm.h>
	#include <fdtdec.h>
	#include <spi.h>
	#include <tpm.h>
	#include <errno.h>
	#include <linux/types.h>
	#include <asm/unaligned.h>
	#include <linux/compat.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_DATA_FIFO 0x24
	#define TPM_INTF_CAPABILITY 0x14

	#define TPM_DUMMY_BYTE 0x00
	#define TPM_WRITE_DIRECTION 0x80

	#define MAX_SPI_LATENCY 15
	#define LOCALITY0 0

	#define ST33ZP24_OK 0x5A
	#define ST33ZP24_UNDEFINED_ERR 0x80
	#define ST33ZP24_BADLOCALITY 0x81
	#define ST33ZP24_TISREGISTER_UKNOWN 0x82
	#define ST33ZP24_LOCALITY_NOT_ACTIVATED 0x83
	#define ST33ZP24_HASH_END_BEFORE_HASH_START 0x84
	#define ST33ZP24_BAD_COMMAND_ORDER 0x85
	#define ST33ZP24_INCORECT_RECEIVED_LENGTH 0x86
	#define ST33ZP24_TPM_FIFO_OVERFLOW 0x89
	#define ST33ZP24_UNEXPECTED_READ_FIFO 0x8A
	#define ST33ZP24_UNEXPECTED_WRITE_FIFO 0x8B
	#define ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END 0x90
	#define ST33ZP24_DUMMY_BYTES 0x00

	/*
	* TPM command can be up to 2048 byte, A TPM response can be up to
	* 1024 byte.
	* Between command and response, there are latency byte (up to 15
	* usually on st33zp24 2 are enough).
	*
	* Overall when sending a command and expecting an answer we need if
	* worst case:
	* 2048 (for the TPM command) + 1024 (for the TPM answer). We need
	* some latency byte before the answer is available (max 15).
	* We have 2048 + 1024 + 15.
	*/
	#define ST33ZP24_SPI_BUFFER_SIZE (TPM_BUFSIZE + (TPM_BUFSIZE / 2) +\
	MAX_SPI_LATENCY)

	struct st33zp24_spi_phy {
	int latency;

	u8 tx_buf[ST33ZP24_SPI_BUFFER_SIZE];
	u8 rx_buf[ST33ZP24_SPI_BUFFER_SIZE];
	};

	static int st33zp24_spi_status_to_errno(u8 code)
	{
	switch (code) {
	case ST33ZP24_OK:
	return 0;
	case ST33ZP24_UNDEFINED_ERR:
	case ST33ZP24_BADLOCALITY:
	case ST33ZP24_TISREGISTER_UKNOWN:
	case ST33ZP24_LOCALITY_NOT_ACTIVATED:
	case ST33ZP24_HASH_END_BEFORE_HASH_START:
	case ST33ZP24_BAD_COMMAND_ORDER:
	case ST33ZP24_UNEXPECTED_READ_FIFO:
	case ST33ZP24_UNEXPECTED_WRITE_FIFO:
	case ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END:
	return -EPROTO;
	case ST33ZP24_INCORECT_RECEIVED_LENGTH:
	case ST33ZP24_TPM_FIFO_OVERFLOW:
	return -EMSGSIZE;
	case ST33ZP24_DUMMY_BYTES:
	return -ENOSYS;
	}
	return code;
	}

	/*
	* st33zp24_spi_send
	* Send byte to TPM register according to the ST33ZP24 SPI protocol.
	* @param: tpm, the chip 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: should be zero if success else a negative error code.
	*/
	static int st33zp24_spi_write(struct udevice *dev, u8 tpm_register,
	const u8 *tpm_data, size_t tpm_size)
	{
	int total_length = 0, ret;
	struct spi_slave *slave = dev_get_parent_priv(dev);
	struct st33zp24_spi_phy *phy = dev_get_platdata(dev);

	u8 tx_buf = (u8 )phy->tx_buf;
	u8 *rx_buf = phy->rx_buf;

	tx_buf[total_length++] = TPM_WRITE_DIRECTION \| LOCALITY0;
	tx_buf[total_length++] = tpm_register;

	if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
	tx_buf[total_length++] = tpm_size >> 8;
	tx_buf[total_length++] = tpm_size;
	}
	memcpy(tx_buf + total_length, tpm_data, tpm_size);
	total_length += tpm_size;

	memset(tx_buf + total_length, TPM_DUMMY_BYTE, phy->latency);

	total_length += phy->latency;

	ret = spi_claim_bus(slave);
	if (ret < 0)
	return ret;

	ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
	SPI_XFER_BEGIN \| SPI_XFER_END);
	if (ret < 0)
	return ret;

	spi_release_bus(slave);

	if (ret == 0)
	ret = rx_buf[total_length - 1];

	return st33zp24_spi_status_to_errno(ret);
	}

	/*
	* spi_st33zp24_spi_read8_reg
	* Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
	* @param: tpm, the chip description
	* @param: tpm_loc, the locality to read register from
	* @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: should be zero if success else a negative error code.
	*/
	static u8 st33zp24_spi_read8_reg(struct udevice *dev, u8 tpm_register,
	u8 *tpm_data, size_t tpm_size)
	{
	int total_length = 0, ret;
	struct spi_slave *slave = dev_get_parent_priv(dev);
	struct st33zp24_spi_phy *phy = dev_get_platdata(dev);

	u8 tx_buf = (u8 )phy->tx_buf;
	u8 *rx_buf = phy->rx_buf;

	/* Pre-Header */
	tx_buf[total_length++] = LOCALITY0;
	tx_buf[total_length++] = tpm_register;

	memset(&tx_buf[total_length], TPM_DUMMY_BYTE,
	phy->latency + tpm_size);
	total_length += phy->latency + tpm_size;

	ret = spi_claim_bus(slave);
	if (ret < 0)
	return 0;

	ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
	SPI_XFER_BEGIN \| SPI_XFER_END);
	if (ret < 0)
	return 0;

	spi_release_bus(slave);

	if (tpm_size > 0 && ret == 0) {
	ret = rx_buf[total_length - tpm_size - 1];
	memcpy(tpm_data, rx_buf + total_length - tpm_size, tpm_size);
	}
	return ret;
	}

	/*
	* st33zp24_spi_recv
	* Recv byte from the TIS register according to the ST33ZP24 SPI 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_spi_read(struct udevice *dev, u8 tpm_register,
	u8 *tpm_data, size_t tpm_size)
	{
	int ret;

	ret = st33zp24_spi_read8_reg(dev, tpm_register, tpm_data, tpm_size);
	if (!st33zp24_spi_status_to_errno(ret))
	return tpm_size;

	return ret;
	}

	static int st33zp24_spi_evaluate_latency(struct udevice *dev)
	{
	int latency = 1, status = 0;
	u8 data = 0;
	struct st33zp24_spi_phy *phy = dev_get_platdata(dev);

	while (!status && latency < MAX_SPI_LATENCY) {
	phy->latency = latency;
	status = st33zp24_spi_read8_reg(dev, TPM_INTF_CAPABILITY,
	&data, 1);
	latency++;
	}
	if (status < 0)
	return status;
	if (latency == MAX_SPI_LATENCY)
	return -ENODEV;

	return latency - 1;
	}

	/*
	* st33zp24_spi_release_locality release the active locality
	* @param: chip, the tpm chip description.
	*/
	static void st33zp24_spi_release_locality(struct udevice *dev)
	{
	u8 data = TPM_ACCESS_ACTIVE_LOCALITY;

	st33zp24_spi_write(dev, TPM_ACCESS, &data, 1);
	}

	/*
	* st33zp24_spi_check_locality if the locality is active
	* @param: chip, the tpm chip description
	* @return: the active locality or -EACCES.
	*/
	static int st33zp24_spi_check_locality(struct udevice *dev)
	{
	u8 data;
	u8 status;
	struct tpm_chip *chip = dev_get_priv(dev);

	status = st33zp24_spi_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_spi_request_locality request the TPM locality
	* @param: chip, the chip description
	* @return: the active locality or negative value.
	*/
	static int st33zp24_spi_request_locality(struct udevice *dev)
	{
	unsigned long start, stop;
	long ret;
	u8 data;
	struct tpm_chip *chip = dev_get_priv(dev);

	if (st33zp24_spi_check_locality(dev) == chip->locality)
	return chip->locality;

	data = TPM_ACCESS_REQUEST_USE;
	ret = st33zp24_spi_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_spi_check_locality(dev) >= 0)
	return chip->locality;
	udelay(TPM_TIMEOUT_MS * 1000);
	} while (get_timer(start) < stop);

	return -EACCES;
	}

	/*
	* st33zp24_spi_status return the TPM_STS register
	* @param: chip, the tpm chip description
	* @return: the TPM_STS register value.
	*/
	static u8 st33zp24_spi_status(struct udevice *dev)
	{
	u8 data;

	st33zp24_spi_read(dev, TPM_STS, &data, 1);
	return data;
	}

	/*
	* st33zp24_spi_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_spi_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_spi_read(dev, tpm_reg, &temp, 1);
	if (status < 0)
	return -EBUSY;

	tpm_reg = TPM_STS + 2;
	burstcnt = temp;
	status = st33zp24_spi_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_spi_cancel, cancel the current command execution or
	* set STS to COMMAND READY.
	* @param: chip, tpm_chip description.
	*/
	static void st33zp24_spi_cancel(struct udevice *dev)
	{
	u8 data;

	data = TPM_STS_COMMAND_READY;
	st33zp24_spi_write(dev, TPM_STS, &data, 1);
	}

	/*
	* st33zp24_spi_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_spi_wait_for_stat(struct udevice *dev, u8 mask,
	unsigned long timeout, int *status)
	{
	unsigned long start, stop;

	/* Check current status */
	*status = st33zp24_spi_status(dev);
	if ((*status & mask) == mask)
	return 0;

	start = get_timer(0);
	stop = timeout;
	do {
	udelay(TPM_TIMEOUT_MS * 1000);
	*status = st33zp24_spi_status(dev);
	if ((*status & mask) == mask)
	return 0;
	} while (get_timer(start) < stop);

	return -ETIME;
	}

	/*
	* st33zp24_spi_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_spi_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_spi_wait_for_stat(dev, TPM_STS_DATA_AVAIL \| TPM_STS_VALID,
	chip->timeout_c, &status) == 0) {
	burstcnt = st33zp24_spi_get_burstcount(dev);
	if (burstcnt < 0)
	return burstcnt;
	len = min_t(int, burstcnt, count - size);
	ret = st33zp24_spi_read(dev, TPM_DATA_FIFO, buf + size, len);
	if (ret < 0)
	return ret;

	size += len;
	}
	return size;
	}

	/*
	* st33zp24_spi_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_spi_recv(struct udevice dev, u8 buf, size_t count)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	int size, expected;

	if (!chip)
	return -ENODEV;

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

	size = st33zp24_spi_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) {
	size = -EIO;
	goto out;
	}

	size += st33zp24_spi_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_spi_cancel(dev);
	st33zp24_spi_release_locality(dev);

	return size;
	}

	/*
	* st33zp24_spi_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_spi_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_spi_request_locality(dev);
	if (ret < 0)
	return ret;

	tpm_stat = st33zp24_spi_status(dev);
	if ((tpm_stat & TPM_STS_COMMAND_READY) == 0) {
	st33zp24_spi_cancel(dev);
	if (st33zp24_spi_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_spi_get_burstcount(dev);
	if (burstcnt < 0)
	return burstcnt;

	size = min_t(int, len - i - 1, burstcnt);
	ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + i, size);
	if (ret < 0)
	goto out_err;

	i += size;
	}

	tpm_stat = st33zp24_spi_status(dev);
	if ((tpm_stat & TPM_STS_DATA_EXPECT) == 0) {
	ret = -EIO;
	goto out_err;
	}

	ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + len - 1, 1);
	if (ret < 0)
	goto out_err;

	tpm_stat = st33zp24_spi_status(dev);
	if ((tpm_stat & TPM_STS_DATA_EXPECT) != 0) {
	ret = -EIO;
	goto out_err;
	}

	data = TPM_STS_GO;
	ret = st33zp24_spi_write(dev, TPM_STS, &data, 1);
	if (ret < 0)
	goto out_err;

	return len;

	out_err:
	st33zp24_spi_cancel(dev);
	st33zp24_spi_release_locality(dev);

	return ret;
	}

	static int st33zp24_spi_cleanup(struct udevice *dev)
	{
	st33zp24_spi_cancel(dev);
	/*
	* The TPM needs some time to clean up here,
	* so we sleep rather than keeping the bus busy
	*/
	mdelay(2);
	st33zp24_spi_release_locality(dev);

	return 0;
	}

	static int st33zp24_spi_init(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);
	struct st33zp24_spi_phy *phy = dev_get_platdata(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;

	phy->latency = st33zp24_spi_evaluate_latency(dev);
	if (phy->latency <= 0)
	return -ENODEV;

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

	return 0;
	}

	static int st33zp24_spi_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_spi_init(dev);
	if (rc < 0)
	chip->is_open = 0;

	return rc;
	}

	static int st33zp24_spi_close(struct udevice *dev)
	{
	struct tpm_chip *chip = dev_get_priv(dev);

	if (chip->is_open) {
	st33zp24_spi_release_locality(dev);
	chip->is_open = 0;
	chip->vend_dev = 0;
	}

	return 0;
	}

	static int st33zp24_spi_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);
	}

	const struct tpm_ops st33zp24_spi_tpm_ops = {
	.open = st33zp24_spi_open,
	.close = st33zp24_spi_close,
	.recv = st33zp24_spi_recv,
	.send = st33zp24_spi_send,
	.cleanup = st33zp24_spi_cleanup,
	.get_desc = st33zp24_spi_get_desc,
	};

	static int st33zp24_spi_probe(struct udevice *dev)
	{
	struct tpm_chip_priv *uc_priv = dev_get_uclass_priv(dev);

	uc_priv->duration_ms[TPM_SHORT] = TIS_SHORT_TIMEOUT_MS;
	uc_priv->duration_ms[TPM_MEDIUM] = TIS_LONG_TIMEOUT_MS;
	uc_priv->duration_ms[TPM_LONG] = TIS_LONG_TIMEOUT_MS;
	uc_priv->retry_time_ms = TPM_TIMEOUT_MS;

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

	return 0;
	}

	static int st33zp24_spi_remove(struct udevice *dev)
	{
	st33zp24_spi_release_locality(dev);

	return 0;
	}

	static const struct udevice_id st33zp24_spi_ids[] = {
	{ .compatible = "st,st33zp24-spi" },
	{ }
	};

	U_BOOT_DRIVER(st33zp24_spi_spi) = {
	.name = "st33zp24-spi",
	.id = UCLASS_TPM,
	.of_match = of_match_ptr(st33zp24_spi_ids),
	.probe = st33zp24_spi_probe,
	.remove = st33zp24_spi_remove,
	.ops = &st33zp24_spi_tpm_ops,
	.priv_auto_alloc_size = sizeof(struct tpm_chip),
	.platdata_auto_alloc_size = sizeof(struct st33zp24_spi_phy),
	};