drivers/char/tpm/st33zp24/spi.c - linux-imx - Git at Google

 /*
  * STMicroelectronics TPM SPI Linux driver for TPM ST33ZP24
  * Copyright (C) 2009 - 2016 STMicroelectronics
  *
  * 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; either version 2 of the License, or
  * (at your option) any later version.
  *
  * 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, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/module.h>
 #include <linux/spi/spi.h>
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/of_irq.h>
 #include <linux/of_gpio.h>
 #include <linux/acpi.h>
 #include <linux/tpm.h>
 #include <linux/platform_data/st33zp24.h>

 #include "../tpm.h"
 #include "st33zp24.h"

 #define TPM_DATA_FIFO           0x24
 #define TPM_INTF_CAPABILITY     0x14

 #define TPM_DUMMY_BYTE		0x00

 #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 {
 	struct spi_device *spi_device;

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

 	int io_lpcpd;
 	int latency;
 };

 static int st33zp24_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 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 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_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
 			     int tpm_size)
 {
 	int total_length = 0, ret = 0;
 	struct st33zp24_spi_phy *phy = phy_id;
 	struct spi_device *dev = phy->spi_device;
 	struct spi_transfer spi_xfer = {
 		.tx_buf = phy->tx_buf,
 		.rx_buf = phy->rx_buf,
 	};

 	/* Pre-Header */
 	phy->tx_buf[total_length++] = TPM_WRITE_DIRECTION | LOCALITY0;
 	phy->tx_buf[total_length++] = tpm_register;

 	if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
 		phy->tx_buf[total_length++] = tpm_size >> 8;
 		phy->tx_buf[total_length++] = tpm_size;
 	}

 	memcpy(&phy->tx_buf[total_length], tpm_data, tpm_size);
 	total_length += tpm_size;

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

 	spi_xfer.len = total_length + phy->latency;

 	ret = spi_sync_transfer(dev, &spi_xfer, 1);
 	if (ret == 0)
 		ret = phy->rx_buf[total_length + phy->latency - 1];

 	return st33zp24_status_to_errno(ret);
 } /* st33zp24_spi_send() */

 /*
  * st33zp24_spi_read8_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: should be zero if success else a negative error code.
  */
 static int st33zp24_spi_read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data,
 				  int tpm_size)
 {
 	int total_length = 0, ret;
 	struct st33zp24_spi_phy *phy = phy_id;
 	struct spi_device *dev = phy->spi_device;
 	struct spi_transfer spi_xfer = {
 		.tx_buf = phy->tx_buf,
 		.rx_buf = phy->rx_buf,
 	};

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

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

 	spi_xfer.len = total_length + phy->latency + tpm_size;

 	/* header + status byte + size of the data + status byte */
 	ret = spi_sync_transfer(dev, &spi_xfer, 1);
 	if (tpm_size > 0 && ret == 0) {
 		ret = phy->rx_buf[total_length + phy->latency - 1];

 		memcpy(tpm_data, phy->rx_buf + total_length + phy->latency,
 		       tpm_size);
 	}

 	return ret;
 } /* st33zp24_spi_read8_reg() */

 /*
  * 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_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
 			     int tpm_size)
 {
 	int ret;

 	ret = st33zp24_spi_read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
 	if (!st33zp24_status_to_errno(ret))
 		return tpm_size;
 	return ret;
 } /* st33zp24_spi_recv() */

 static int st33zp24_spi_evaluate_latency(void *phy_id)
 {
 	struct st33zp24_spi_phy *phy = phy_id;
 	int latency = 1, status = 0;
 	u8 data = 0;

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

 	return latency - 1;
 } /* evaluate_latency() */

 static const struct st33zp24_phy_ops spi_phy_ops = {
 	.send = st33zp24_spi_send,
 	.recv = st33zp24_spi_recv,
 };

 static const struct acpi_gpio_params lpcpd_gpios = { 1, 0, false };

 static const struct acpi_gpio_mapping acpi_st33zp24_gpios[] = {
 	{ "lpcpd-gpios", &lpcpd_gpios, 1 },
 	{},
 };

 static int st33zp24_spi_acpi_request_resources(struct spi_device *spi_dev)
 {
 	struct tpm_chip *chip = spi_get_drvdata(spi_dev);
 	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 	struct st33zp24_spi_phy *phy = tpm_dev->phy_id;
 	struct gpio_desc *gpiod_lpcpd;
 	struct device *dev = &spi_dev->dev;
 	int ret;

 	ret = devm_acpi_dev_add_driver_gpios(dev, acpi_st33zp24_gpios);
 	if (ret)
 		return ret;

 	/* Get LPCPD GPIO from ACPI */
 	gpiod_lpcpd = devm_gpiod_get(dev, "lpcpd", GPIOD_OUT_HIGH);
 	if (IS_ERR(gpiod_lpcpd)) {
 		dev_err(dev, "Failed to retrieve lpcpd-gpios from acpi.\n");
 		phy->io_lpcpd = -1;
 		/*
 		 * lpcpd pin is not specified. This is not an issue as
 		 * power management can be also managed by TPM specific
 		 * commands. So leave with a success status code.
 		 */
 		return 0;
 	}

 	phy->io_lpcpd = desc_to_gpio(gpiod_lpcpd);

 	return 0;
 }

 static int st33zp24_spi_of_request_resources(struct spi_device *spi_dev)
 {
 	struct tpm_chip *chip = spi_get_drvdata(spi_dev);
 	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 	struct st33zp24_spi_phy *phy = tpm_dev->phy_id;
 	struct device_node *pp;
 	int gpio;
 	int ret;

 	pp = spi_dev->dev.of_node;
 	if (!pp) {
 		dev_err(&spi_dev->dev, "No platform data\n");
 		return -ENODEV;
 	}

 	/* Get GPIO from device tree */
 	gpio = of_get_named_gpio(pp, "lpcpd-gpios", 0);
 	if (gpio < 0) {
 		dev_err(&spi_dev->dev,
 			"Failed to retrieve lpcpd-gpios from dts.\n");
 		phy->io_lpcpd = -1;
 		/*
 		 * lpcpd pin is not specified. This is not an issue as
 		 * power management can be also managed by TPM specific
 		 * commands. So leave with a success status code.
 		 */
 		return 0;
 	}
 	/* GPIO request and configuration */
 	ret = devm_gpio_request_one(&spi_dev->dev, gpio,
 			GPIOF_OUT_INIT_HIGH, "TPM IO LPCPD");
 	if (ret) {
 		dev_err(&spi_dev->dev, "Failed to request lpcpd pin\n");
 		return -ENODEV;
 	}
 	phy->io_lpcpd = gpio;

 	return 0;
 }

 static int st33zp24_spi_request_resources(struct spi_device *dev)
 {
 	struct tpm_chip *chip = spi_get_drvdata(dev);
 	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
 	struct st33zp24_spi_phy *phy = tpm_dev->phy_id;
 	struct st33zp24_platform_data *pdata;
 	int ret;

 	pdata = dev->dev.platform_data;
 	if (!pdata) {
 		dev_err(&dev->dev, "No platform data\n");
 		return -ENODEV;
 	}

 	/* store for late use */
 	phy->io_lpcpd = pdata->io_lpcpd;

 	if (gpio_is_valid(pdata->io_lpcpd)) {
 		ret = devm_gpio_request_one(&dev->dev,
 				pdata->io_lpcpd, GPIOF_OUT_INIT_HIGH,
 				"TPM IO_LPCPD");
 		if (ret) {
 			dev_err(&dev->dev, "%s : reset gpio_request failed\n",
 				__FILE__);
 			return ret;
 		}
 	}

 	return 0;
 }

 /*
  * st33zp24_spi_probe initialize the TPM device
  * @param: dev, the spi_device drescription (TPM SPI description).
  * @return: 0 in case of success.
  *	 or a negative value describing the error.
  */
 static int st33zp24_spi_probe(struct spi_device *dev)
 {
 	int ret;
 	struct st33zp24_platform_data *pdata;
 	struct st33zp24_spi_phy *phy;

 	/* Check SPI platform functionnalities */
 	if (!dev) {
 		pr_info("%s: dev is NULL. Device is not accessible.\n",
 			__func__);
 		return -ENODEV;
 	}

 	phy = devm_kzalloc(&dev->dev, sizeof(struct st33zp24_spi_phy),
 			   GFP_KERNEL);
 	if (!phy)
 		return -ENOMEM;

 	phy->spi_device = dev;

 	pdata = dev->dev.platform_data;
 	if (!pdata && dev->dev.of_node) {
 		ret = st33zp24_spi_of_request_resources(dev);
 		if (ret)
 			return ret;
 	} else if (pdata) {
 		ret = st33zp24_spi_request_resources(dev);
 		if (ret)
 			return ret;
 	} else if (ACPI_HANDLE(&dev->dev)) {
 		ret = st33zp24_spi_acpi_request_resources(dev);
 		if (ret)
 			return ret;
 	}

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

 	return st33zp24_probe(phy, &spi_phy_ops, &dev->dev, dev->irq,
 			      phy->io_lpcpd);
 }

 /*
  * st33zp24_spi_remove remove the TPM device
  * @param: client, the spi_device drescription (TPM SPI description).
  * @return: 0 in case of success.
  */
 static int st33zp24_spi_remove(struct spi_device *dev)
 {
 	struct tpm_chip *chip = spi_get_drvdata(dev);
 	int ret;

 	ret = st33zp24_remove(chip);
 	if (ret)
 		return ret;

 	return 0;
 }

 static const struct spi_device_id st33zp24_spi_id[] = {
 	{TPM_ST33_SPI, 0},
 	{}
 };
 MODULE_DEVICE_TABLE(spi, st33zp24_spi_id);

 static const struct of_device_id of_st33zp24_spi_match[] = {
 	{ .compatible = "st,st33zp24-spi", },
 	{}
 };
 MODULE_DEVICE_TABLE(of, of_st33zp24_spi_match);

 static const struct acpi_device_id st33zp24_spi_acpi_match[] = {
 	{"SMO3324"},
 	{}
 };
 MODULE_DEVICE_TABLE(acpi, st33zp24_spi_acpi_match);

 static SIMPLE_DEV_PM_OPS(st33zp24_spi_ops, st33zp24_pm_suspend,
 			 st33zp24_pm_resume);

 static struct spi_driver st33zp24_spi_driver = {
 	.driver = {
 		.name = TPM_ST33_SPI,
 		.pm = &st33zp24_spi_ops,
 		.of_match_table = of_match_ptr(of_st33zp24_spi_match),
 		.acpi_match_table = ACPI_PTR(st33zp24_spi_acpi_match),
 	},
 	.probe = st33zp24_spi_probe,
 	.remove = st33zp24_spi_remove,
 	.id_table = st33zp24_spi_id,
 };

 module_spi_driver(st33zp24_spi_driver);

 MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
 MODULE_DESCRIPTION("STM TPM 1.2 SPI ST33 Driver");
 MODULE_VERSION("1.3.0");
 MODULE_LICENSE("GPL");
	/*
	* STMicroelectronics TPM SPI Linux driver for TPM ST33ZP24
	* Copyright (C) 2009 - 2016 STMicroelectronics
	*
	* 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; either version 2 of the License, or
	* (at your option) any later version.
	*
	* 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, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/module.h>
	#include <linux/spi/spi.h>
	#include <linux/gpio.h>
	#include <linux/gpio/consumer.h>
	#include <linux/of_irq.h>
	#include <linux/of_gpio.h>
	#include <linux/acpi.h>
	#include <linux/tpm.h>
	#include <linux/platform_data/st33zp24.h>

	#include "../tpm.h"
	#include "st33zp24.h"

	#define TPM_DATA_FIFO 0x24
	#define TPM_INTF_CAPABILITY 0x14

	#define TPM_DUMMY_BYTE 0x00

	#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 {
	struct spi_device *spi_device;

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

	int io_lpcpd;
	int latency;
	};

	static int st33zp24_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 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 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_send(void phy_id, u8 tpm_register, u8 tpm_data,
	int tpm_size)
	{
	int total_length = 0, ret = 0;
	struct st33zp24_spi_phy *phy = phy_id;
	struct spi_device *dev = phy->spi_device;
	struct spi_transfer spi_xfer = {
	.tx_buf = phy->tx_buf,
	.rx_buf = phy->rx_buf,
	};

	/* Pre-Header */
	phy->tx_buf[total_length++] = TPM_WRITE_DIRECTION \| LOCALITY0;
	phy->tx_buf[total_length++] = tpm_register;

	if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
	phy->tx_buf[total_length++] = tpm_size >> 8;
	phy->tx_buf[total_length++] = tpm_size;
	}

	memcpy(&phy->tx_buf[total_length], tpm_data, tpm_size);
	total_length += tpm_size;

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

	spi_xfer.len = total_length + phy->latency;

	ret = spi_sync_transfer(dev, &spi_xfer, 1);
	if (ret == 0)
	ret = phy->rx_buf[total_length + phy->latency - 1];

	return st33zp24_status_to_errno(ret);
	} /* st33zp24_spi_send() */

	/*
	* st33zp24_spi_read8_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: should be zero if success else a negative error code.
	*/
	static int st33zp24_spi_read8_reg(void phy_id, u8 tpm_register, u8 tpm_data,
	int tpm_size)
	{
	int total_length = 0, ret;
	struct st33zp24_spi_phy *phy = phy_id;
	struct spi_device *dev = phy->spi_device;
	struct spi_transfer spi_xfer = {
	.tx_buf = phy->tx_buf,
	.rx_buf = phy->rx_buf,
	};

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

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

	spi_xfer.len = total_length + phy->latency + tpm_size;

	/* header + status byte + size of the data + status byte */
	ret = spi_sync_transfer(dev, &spi_xfer, 1);
	if (tpm_size > 0 && ret == 0) {
	ret = phy->rx_buf[total_length + phy->latency - 1];

	memcpy(tpm_data, phy->rx_buf + total_length + phy->latency,
	tpm_size);
	}

	return ret;
	} /* st33zp24_spi_read8_reg() */

	/*
	* 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_recv(void phy_id, u8 tpm_register, u8 tpm_data,
	int tpm_size)
	{
	int ret;

	ret = st33zp24_spi_read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
	if (!st33zp24_status_to_errno(ret))
	return tpm_size;
	return ret;
	} /* st33zp24_spi_recv() */

	static int st33zp24_spi_evaluate_latency(void *phy_id)
	{
	struct st33zp24_spi_phy *phy = phy_id;
	int latency = 1, status = 0;
	u8 data = 0;

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

	return latency - 1;
	} /* evaluate_latency() */

	static const struct st33zp24_phy_ops spi_phy_ops = {
	.send = st33zp24_spi_send,
	.recv = st33zp24_spi_recv,
	};

	static const struct acpi_gpio_params lpcpd_gpios = { 1, 0, false };

	static const struct acpi_gpio_mapping acpi_st33zp24_gpios[] = {
	{ "lpcpd-gpios", &lpcpd_gpios, 1 },
	{},
	};

	static int st33zp24_spi_acpi_request_resources(struct spi_device *spi_dev)
	{
	struct tpm_chip *chip = spi_get_drvdata(spi_dev);
	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
	struct st33zp24_spi_phy *phy = tpm_dev->phy_id;
	struct gpio_desc *gpiod_lpcpd;
	struct device *dev = &spi_dev->dev;
	int ret;

	ret = devm_acpi_dev_add_driver_gpios(dev, acpi_st33zp24_gpios);
	if (ret)
	return ret;

	/* Get LPCPD GPIO from ACPI */
	gpiod_lpcpd = devm_gpiod_get(dev, "lpcpd", GPIOD_OUT_HIGH);
	if (IS_ERR(gpiod_lpcpd)) {
	dev_err(dev, "Failed to retrieve lpcpd-gpios from acpi.\n");
	phy->io_lpcpd = -1;
	/*
	* lpcpd pin is not specified. This is not an issue as
	* power management can be also managed by TPM specific
	* commands. So leave with a success status code.
	*/
	return 0;
	}

	phy->io_lpcpd = desc_to_gpio(gpiod_lpcpd);

	return 0;
	}

	static int st33zp24_spi_of_request_resources(struct spi_device *spi_dev)
	{
	struct tpm_chip *chip = spi_get_drvdata(spi_dev);
	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
	struct st33zp24_spi_phy *phy = tpm_dev->phy_id;
	struct device_node *pp;
	int gpio;
	int ret;

	pp = spi_dev->dev.of_node;
	if (!pp) {
	dev_err(&spi_dev->dev, "No platform data\n");
	return -ENODEV;
	}

	/* Get GPIO from device tree */
	gpio = of_get_named_gpio(pp, "lpcpd-gpios", 0);
	if (gpio < 0) {
	dev_err(&spi_dev->dev,
	"Failed to retrieve lpcpd-gpios from dts.\n");
	phy->io_lpcpd = -1;
	/*
	* lpcpd pin is not specified. This is not an issue as
	* power management can be also managed by TPM specific
	* commands. So leave with a success status code.
	*/
	return 0;
	}
	/* GPIO request and configuration */
	ret = devm_gpio_request_one(&spi_dev->dev, gpio,
	GPIOF_OUT_INIT_HIGH, "TPM IO LPCPD");
	if (ret) {
	dev_err(&spi_dev->dev, "Failed to request lpcpd pin\n");
	return -ENODEV;
	}
	phy->io_lpcpd = gpio;

	return 0;
	}

	static int st33zp24_spi_request_resources(struct spi_device *dev)
	{
	struct tpm_chip *chip = spi_get_drvdata(dev);
	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
	struct st33zp24_spi_phy *phy = tpm_dev->phy_id;
	struct st33zp24_platform_data *pdata;
	int ret;

	pdata = dev->dev.platform_data;
	if (!pdata) {
	dev_err(&dev->dev, "No platform data\n");
	return -ENODEV;
	}

	/* store for late use */
	phy->io_lpcpd = pdata->io_lpcpd;

	if (gpio_is_valid(pdata->io_lpcpd)) {
	ret = devm_gpio_request_one(&dev->dev,
	pdata->io_lpcpd, GPIOF_OUT_INIT_HIGH,
	"TPM IO_LPCPD");
	if (ret) {
	dev_err(&dev->dev, "%s : reset gpio_request failed\n",
	__FILE__);
	return ret;
	}
	}

	return 0;
	}

	/*
	* st33zp24_spi_probe initialize the TPM device
	* @param: dev, the spi_device drescription (TPM SPI description).
	* @return: 0 in case of success.
	* or a negative value describing the error.
	*/
	static int st33zp24_spi_probe(struct spi_device *dev)
	{
	int ret;
	struct st33zp24_platform_data *pdata;
	struct st33zp24_spi_phy *phy;

	/* Check SPI platform functionnalities */
	if (!dev) {
	pr_info("%s: dev is NULL. Device is not accessible.\n",
	__func__);
	return -ENODEV;
	}

	phy = devm_kzalloc(&dev->dev, sizeof(struct st33zp24_spi_phy),
	GFP_KERNEL);
	if (!phy)
	return -ENOMEM;

	phy->spi_device = dev;

	pdata = dev->dev.platform_data;
	if (!pdata && dev->dev.of_node) {
	ret = st33zp24_spi_of_request_resources(dev);
	if (ret)
	return ret;
	} else if (pdata) {
	ret = st33zp24_spi_request_resources(dev);
	if (ret)
	return ret;
	} else if (ACPI_HANDLE(&dev->dev)) {
	ret = st33zp24_spi_acpi_request_resources(dev);
	if (ret)
	return ret;
	}

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

	return st33zp24_probe(phy, &spi_phy_ops, &dev->dev, dev->irq,
	phy->io_lpcpd);
	}

	/*
	* st33zp24_spi_remove remove the TPM device
	* @param: client, the spi_device drescription (TPM SPI description).
	* @return: 0 in case of success.
	*/
	static int st33zp24_spi_remove(struct spi_device *dev)
	{
	struct tpm_chip *chip = spi_get_drvdata(dev);
	int ret;

	ret = st33zp24_remove(chip);
	if (ret)
	return ret;

	return 0;
	}

	static const struct spi_device_id st33zp24_spi_id[] = {
	{TPM_ST33_SPI, 0},
	{}
	};
	MODULE_DEVICE_TABLE(spi, st33zp24_spi_id);

	static const struct of_device_id of_st33zp24_spi_match[] = {
	{ .compatible = "st,st33zp24-spi", },
	{}
	};
	MODULE_DEVICE_TABLE(of, of_st33zp24_spi_match);

	static const struct acpi_device_id st33zp24_spi_acpi_match[] = {
	{"SMO3324"},
	{}
	};
	MODULE_DEVICE_TABLE(acpi, st33zp24_spi_acpi_match);

	static SIMPLE_DEV_PM_OPS(st33zp24_spi_ops, st33zp24_pm_suspend,
	st33zp24_pm_resume);

	static struct spi_driver st33zp24_spi_driver = {
	.driver = {
	.name = TPM_ST33_SPI,
	.pm = &st33zp24_spi_ops,
	.of_match_table = of_match_ptr(of_st33zp24_spi_match),
	.acpi_match_table = ACPI_PTR(st33zp24_spi_acpi_match),
	},
	.probe = st33zp24_spi_probe,
	.remove = st33zp24_spi_remove,
	.id_table = st33zp24_spi_id,
	};

	module_spi_driver(st33zp24_spi_driver);

	MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
	MODULE_DESCRIPTION("STM TPM 1.2 SPI ST33 Driver");
	MODULE_VERSION("1.3.0");
	MODULE_LICENSE("GPL");