drivers/char/tpm/tpm_ftpm_tee.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) Microsoft Corporation
  *
  * Implements a firmware TPM as described here:
  * https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
  *
  * A reference implementation is available here:
  * https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
  */

 #include <linux/acpi.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/tee_drv.h>
 #include <linux/tpm.h>
 #include <linux/uuid.h>

 #include "tpm.h"
 #include "tpm_ftpm_tee.h"

 /*
  * TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896
  *
  * Randomly generated, and must correspond to the GUID on the TA side.
  * Defined here in the reference implementation:
  * https://github.com/microsoft/ms-tpm-20-ref/blob/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM/include/fTPM.h#L42
  */
 static const uuid_t ftpm_ta_uuid =
 	UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4,
 		  0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96);

 /**
  * ftpm_tee_tpm_op_recv() - retrieve fTPM response.
  * @chip:	the tpm_chip description as specified in driver/char/tpm/tpm.h.
  * @buf:	the buffer to store data.
  * @count:	the number of bytes to read.
  *
  * Return:
  *	In case of success the number of bytes received.
  *	On failure, -errno.
  */
 static int ftpm_tee_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
 	size_t len;

 	len = pvt_data->resp_len;
 	if (count < len) {
 		dev_err(&chip->dev,
 			"%s: Invalid size in recv: count=%zd, resp_len=%zd\n",
 			__func__, count, len);
 		return -EIO;
 	}

 	memcpy(buf, pvt_data->resp_buf, len);
 	pvt_data->resp_len = 0;

 	return len;
 }

 /**
  * ftpm_tee_tpm_op_send() - send TPM commands through the TEE shared memory.
  * @chip:	the tpm_chip description as specified in driver/char/tpm/tpm.h
  * @buf:	the buffer to send.
  * @len:	the number of bytes to send.
  *
  * Return:
  *	In case of success, returns 0.
  *	On failure, -errno
  */
 static int ftpm_tee_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t len)
 {
 	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
 	size_t resp_len;
 	int rc;
 	u8 *temp_buf;
 	struct tpm_header *resp_header;
 	struct tee_ioctl_invoke_arg transceive_args;
 	struct tee_param command_params[4];
 	struct tee_shm *shm = pvt_data->shm;

 	if (len > MAX_COMMAND_SIZE) {
 		dev_err(&chip->dev,
 			"%s: len=%zd exceeds MAX_COMMAND_SIZE supported by fTPM TA\n",
 			__func__, len);
 		return -EIO;
 	}

 	memset(&transceive_args, 0, sizeof(transceive_args));
 	memset(command_params, 0, sizeof(command_params));
 	pvt_data->resp_len = 0;

 	/* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
 	transceive_args = (struct tee_ioctl_invoke_arg) {
 		.func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
 		.session = pvt_data->session,
 		.num_params = 4,
 	};

 	/* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
 	command_params[0] = (struct tee_param) {
 		.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT,
 		.u.memref = {
 			.shm = shm,
 			.size = len,
 			.shm_offs = 0,
 		},
 	};

 	temp_buf = tee_shm_get_va(shm, 0);
 	if (IS_ERR(temp_buf)) {
 		dev_err(&chip->dev, "%s: tee_shm_get_va failed for transmit\n",
 			__func__);
 		return PTR_ERR(temp_buf);
 	}
 	memset(temp_buf, 0, (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
 	memcpy(temp_buf, buf, len);

 	command_params[1] = (struct tee_param) {
 		.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
 		.u.memref = {
 			.shm = shm,
 			.size = MAX_RESPONSE_SIZE,
 			.shm_offs = MAX_COMMAND_SIZE,
 		},
 	};

 	rc = tee_client_invoke_func(pvt_data->ctx, &transceive_args,
 				    command_params);
 	if ((rc < 0) || (transceive_args.ret != 0)) {
 		dev_err(&chip->dev, "%s: SUBMIT_COMMAND invoke error: 0x%x\n",
 			__func__, transceive_args.ret);
 		return (rc < 0) ? rc : transceive_args.ret;
 	}

 	temp_buf = tee_shm_get_va(shm, command_params[1].u.memref.shm_offs);
 	if (IS_ERR(temp_buf)) {
 		dev_err(&chip->dev, "%s: tee_shm_get_va failed for receive\n",
 			__func__);
 		return PTR_ERR(temp_buf);
 	}

 	resp_header = (struct tpm_header *)temp_buf;
 	resp_len = be32_to_cpu(resp_header->length);

 	/* sanity check resp_len */
 	if (resp_len < TPM_HEADER_SIZE) {
 		dev_err(&chip->dev, "%s: tpm response header too small\n",
 			__func__);
 		return -EIO;
 	}
 	if (resp_len > MAX_RESPONSE_SIZE) {
 		dev_err(&chip->dev,
 			"%s: resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
 			__func__, resp_len);
 		return -EIO;
 	}

 	/* sanity checks look good, cache the response */
 	memcpy(pvt_data->resp_buf, temp_buf, resp_len);
 	pvt_data->resp_len = resp_len;

 	return 0;
 }

 static void ftpm_tee_tpm_op_cancel(struct tpm_chip *chip)
 {
 	/* not supported */
 }

 static u8 ftpm_tee_tpm_op_status(struct tpm_chip *chip)
 {
 	return 0;
 }

 static bool ftpm_tee_tpm_req_canceled(struct tpm_chip *chip, u8 status)
 {
 	return 0;
 }

 static const struct tpm_class_ops ftpm_tee_tpm_ops = {
 	.flags = TPM_OPS_AUTO_STARTUP,
 	.recv = ftpm_tee_tpm_op_recv,
 	.send = ftpm_tee_tpm_op_send,
 	.cancel = ftpm_tee_tpm_op_cancel,
 	.status = ftpm_tee_tpm_op_status,
 	.req_complete_mask = 0,
 	.req_complete_val = 0,
 	.req_canceled = ftpm_tee_tpm_req_canceled,
 };

 /*
  * Check whether this driver supports the fTPM TA in the TEE instance
  * represented by the params (ver/data) to this function.
  */
 static int ftpm_tee_match(struct tee_ioctl_version_data *ver, const void *data)
 {
 	/*
 	 * Currently this driver only support GP Complaint OPTEE based fTPM TA
 	 */
 	if ((ver->impl_id == TEE_IMPL_ID_OPTEE) &&
 		(ver->gen_caps & TEE_GEN_CAP_GP))
 		return 1;
 	else
 		return 0;
 }

 /**
  * ftpm_tee_probe() - initialize the fTPM
  * @pdev: the platform_device description.
  *
  * Return:
  *	On success, 0. On failure, -errno.
  */
 static int ftpm_tee_probe(struct device *dev)
 {
 	int rc;
 	struct tpm_chip *chip;
 	struct ftpm_tee_private *pvt_data = NULL;
 	struct tee_ioctl_open_session_arg sess_arg;

 	pvt_data = devm_kzalloc(dev, sizeof(struct ftpm_tee_private),
 				GFP_KERNEL);
 	if (!pvt_data)
 		return -ENOMEM;

 	dev_set_drvdata(dev, pvt_data);

 	/* Open context with TEE driver */
 	pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL,
 						NULL);
 	if (IS_ERR(pvt_data->ctx)) {
 		if (PTR_ERR(pvt_data->ctx) == -ENOENT)
 			return -EPROBE_DEFER;
 		dev_err(dev, "%s: tee_client_open_context failed\n", __func__);
 		return PTR_ERR(pvt_data->ctx);
 	}

 	/* Open a session with fTPM TA */
 	memset(&sess_arg, 0, sizeof(sess_arg));
 	export_uuid(sess_arg.uuid, &ftpm_ta_uuid);
 	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
 	sess_arg.num_params = 0;

 	rc = tee_client_open_session(pvt_data->ctx, &sess_arg, NULL);
 	if ((rc < 0) || (sess_arg.ret != 0)) {
 		dev_err(dev, "%s: tee_client_open_session failed, err=%x\n",
 			__func__, sess_arg.ret);
 		rc = -EINVAL;
 		goto out_tee_session;
 	}
 	pvt_data->session = sess_arg.session;

 	/* Allocate dynamic shared memory with fTPM TA */
 	pvt_data->shm = tee_shm_alloc_kernel_buf(pvt_data->ctx,
 						 MAX_COMMAND_SIZE +
 						 MAX_RESPONSE_SIZE);
 	if (IS_ERR(pvt_data->shm)) {
 		dev_err(dev, "%s: tee_shm_alloc_kernel_buf failed\n", __func__);
 		rc = -ENOMEM;
 		goto out_shm_alloc;
 	}

 	/* Allocate new struct tpm_chip instance */
 	chip = tpm_chip_alloc(dev, &ftpm_tee_tpm_ops);
 	if (IS_ERR(chip)) {
 		dev_err(dev, "%s: tpm_chip_alloc failed\n", __func__);
 		rc = PTR_ERR(chip);
 		goto out_chip_alloc;
 	}

 	pvt_data->chip = chip;
 	pvt_data->chip->flags |= TPM_CHIP_FLAG_TPM2;

 	/* Create a character device for the fTPM */
 	rc = tpm_chip_register(pvt_data->chip);
 	if (rc) {
 		dev_err(dev, "%s: tpm_chip_register failed with rc=%d\n",
 			__func__, rc);
 		goto out_chip;
 	}

 	return 0;

 out_chip:
 	put_device(&pvt_data->chip->dev);
 out_chip_alloc:
 	tee_shm_free(pvt_data->shm);
 out_shm_alloc:
 	tee_client_close_session(pvt_data->ctx, pvt_data->session);
 out_tee_session:
 	tee_client_close_context(pvt_data->ctx);

 	return rc;
 }

 static int ftpm_plat_tee_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;

 	return ftpm_tee_probe(dev);
 }

 /**
  * ftpm_tee_remove() - remove the TPM device
  * @pdev: the platform_device description.
  *
  * Return:
  *	0 always.
  */
 static int ftpm_tee_remove(struct device *dev)
 {
 	struct ftpm_tee_private *pvt_data = dev_get_drvdata(dev);

 	/* Release the chip */
 	tpm_chip_unregister(pvt_data->chip);

 	/* frees chip */
 	put_device(&pvt_data->chip->dev);

 	/* Free the shared memory pool */
 	tee_shm_free(pvt_data->shm);

 	/* close the existing session with fTPM TA*/
 	tee_client_close_session(pvt_data->ctx, pvt_data->session);

 	/* close the context with TEE driver */
 	tee_client_close_context(pvt_data->ctx);

 	/* memory allocated with devm_kzalloc() is freed automatically */

 	return 0;
 }

 static int ftpm_plat_tee_remove(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;

 	return ftpm_tee_remove(dev);
 }

 /**
  * ftpm_tee_shutdown() - shutdown the TPM device
  * @pdev: the platform_device description.
  */
 static void ftpm_plat_tee_shutdown(struct platform_device *pdev)
 {
 	struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev);

 	tee_shm_free(pvt_data->shm);
 	tee_client_close_session(pvt_data->ctx, pvt_data->session);
 	tee_client_close_context(pvt_data->ctx);
 }

 static const struct of_device_id of_ftpm_tee_ids[] = {
 	{ .compatible = "microsoft,ftpm" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids);

 static struct platform_driver ftpm_tee_plat_driver = {
 	.driver = {
 		.name = "ftpm-tee",
 		.of_match_table = of_match_ptr(of_ftpm_tee_ids),
 	},
 	.shutdown = ftpm_plat_tee_shutdown,
 	.probe = ftpm_plat_tee_probe,
 	.remove = ftpm_plat_tee_remove,
 };

 /* UUID of the fTPM TA */
 static const struct tee_client_device_id optee_ftpm_id_table[] = {
 	{UUID_INIT(0xbc50d971, 0xd4c9, 0x42c4,
 		   0x82, 0xcb, 0x34, 0x3f, 0xb7, 0xf3, 0x78, 0x96)},
 	{}
 };

 MODULE_DEVICE_TABLE(tee, optee_ftpm_id_table);

 static struct tee_client_driver ftpm_tee_driver = {
 	.id_table	= optee_ftpm_id_table,
 	.driver		= {
 		.name		= "optee-ftpm",
 		.bus		= &tee_bus_type,
 		.probe		= ftpm_tee_probe,
 		.remove		= ftpm_tee_remove,
 	},
 };

 static int __init ftpm_mod_init(void)
 {
 	int rc;

 	rc = platform_driver_register(&ftpm_tee_plat_driver);
 	if (rc)
 		return rc;

 	return driver_register(&ftpm_tee_driver.driver);
 }

 static void __exit ftpm_mod_exit(void)
 {
 	platform_driver_unregister(&ftpm_tee_plat_driver);
 	driver_unregister(&ftpm_tee_driver.driver);
 }

 module_init(ftpm_mod_init);
 module_exit(ftpm_mod_exit);

 MODULE_AUTHOR("Thirupathaiah Annapureddy <thiruan@microsoft.com>");
 MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) Microsoft Corporation
	*
	* Implements a firmware TPM as described here:
	* https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
	*
	* A reference implementation is available here:
	* https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
	*/

	#include <linux/acpi.h>
	#include <linux/of.h>
	#include <linux/of_platform.h>
	#include <linux/platform_device.h>
	#include <linux/tee_drv.h>
	#include <linux/tpm.h>
	#include <linux/uuid.h>

	#include "tpm.h"
	#include "tpm_ftpm_tee.h"

	/*
	* TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896
	*
	* Randomly generated, and must correspond to the GUID on the TA side.
	* Defined here in the reference implementation:
	* https://github.com/microsoft/ms-tpm-20-ref/blob/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM/include/fTPM.h#L42
	*/
	static const uuid_t ftpm_ta_uuid =
	UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4,
	0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96);

	/**
	* ftpm_tee_tpm_op_recv() - retrieve fTPM response.
	* @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h.
	* @buf: the buffer to store data.
	* @count: the number of bytes to read.
	*
	* Return:
	* In case of success the number of bytes received.
	* On failure, -errno.
	*/
	static int ftpm_tee_tpm_op_recv(struct tpm_chip chip, u8 buf, size_t count)
	{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
	size_t len;

	len = pvt_data->resp_len;
	if (count < len) {
	dev_err(&chip->dev,
	"%s: Invalid size in recv: count=%zd, resp_len=%zd\n",
	__func__, count, len);
	return -EIO;
	}

	memcpy(buf, pvt_data->resp_buf, len);
	pvt_data->resp_len = 0;

	return len;
	}

	/**
	* ftpm_tee_tpm_op_send() - send TPM commands through the TEE shared memory.
	* @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h
	* @buf: the buffer to send.
	* @len: the number of bytes to send.
	*
	* Return:
	* In case of success, returns 0.
	* On failure, -errno
	*/
	static int ftpm_tee_tpm_op_send(struct tpm_chip chip, u8 buf, size_t len)
	{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
	size_t resp_len;
	int rc;
	u8 *temp_buf;
	struct tpm_header *resp_header;
	struct tee_ioctl_invoke_arg transceive_args;
	struct tee_param command_params[4];
	struct tee_shm *shm = pvt_data->shm;

	if (len > MAX_COMMAND_SIZE) {
	dev_err(&chip->dev,
	"%s: len=%zd exceeds MAX_COMMAND_SIZE supported by fTPM TA\n",
	__func__, len);
	return -EIO;
	}

	memset(&transceive_args, 0, sizeof(transceive_args));
	memset(command_params, 0, sizeof(command_params));
	pvt_data->resp_len = 0;

	/* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
	transceive_args = (struct tee_ioctl_invoke_arg) {
	.func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
	.session = pvt_data->session,
	.num_params = 4,
	};

	/* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
	command_params[0] = (struct tee_param) {
	.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT,
	.u.memref = {
	.shm = shm,
	.size = len,
	.shm_offs = 0,
	},
	};

	temp_buf = tee_shm_get_va(shm, 0);
	if (IS_ERR(temp_buf)) {
	dev_err(&chip->dev, "%s: tee_shm_get_va failed for transmit\n",
	__func__);
	return PTR_ERR(temp_buf);
	}
	memset(temp_buf, 0, (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
	memcpy(temp_buf, buf, len);

	command_params[1] = (struct tee_param) {
	.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
	.u.memref = {
	.shm = shm,
	.size = MAX_RESPONSE_SIZE,
	.shm_offs = MAX_COMMAND_SIZE,
	},
	};

	rc = tee_client_invoke_func(pvt_data->ctx, &transceive_args,
	command_params);
	if ((rc < 0) \|\| (transceive_args.ret != 0)) {
	dev_err(&chip->dev, "%s: SUBMIT_COMMAND invoke error: 0x%x\n",
	__func__, transceive_args.ret);
	return (rc < 0) ? rc : transceive_args.ret;
	}

	temp_buf = tee_shm_get_va(shm, command_params[1].u.memref.shm_offs);
	if (IS_ERR(temp_buf)) {
	dev_err(&chip->dev, "%s: tee_shm_get_va failed for receive\n",
	__func__);
	return PTR_ERR(temp_buf);
	}

	resp_header = (struct tpm_header *)temp_buf;
	resp_len = be32_to_cpu(resp_header->length);

	/* sanity check resp_len */
	if (resp_len < TPM_HEADER_SIZE) {
	dev_err(&chip->dev, "%s: tpm response header too small\n",
	__func__);
	return -EIO;
	}
	if (resp_len > MAX_RESPONSE_SIZE) {
	dev_err(&chip->dev,
	"%s: resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
	__func__, resp_len);
	return -EIO;
	}

	/* sanity checks look good, cache the response */
	memcpy(pvt_data->resp_buf, temp_buf, resp_len);
	pvt_data->resp_len = resp_len;

	return 0;
	}

	static void ftpm_tee_tpm_op_cancel(struct tpm_chip *chip)
	{
	/* not supported */
	}

	static u8 ftpm_tee_tpm_op_status(struct tpm_chip *chip)
	{
	return 0;
	}

	static bool ftpm_tee_tpm_req_canceled(struct tpm_chip *chip, u8 status)
	{
	return 0;
	}

	static const struct tpm_class_ops ftpm_tee_tpm_ops = {
	.flags = TPM_OPS_AUTO_STARTUP,
	.recv = ftpm_tee_tpm_op_recv,
	.send = ftpm_tee_tpm_op_send,
	.cancel = ftpm_tee_tpm_op_cancel,
	.status = ftpm_tee_tpm_op_status,
	.req_complete_mask = 0,
	.req_complete_val = 0,
	.req_canceled = ftpm_tee_tpm_req_canceled,
	};

	/*
	* Check whether this driver supports the fTPM TA in the TEE instance
	* represented by the params (ver/data) to this function.
	*/
	static int ftpm_tee_match(struct tee_ioctl_version_data ver, const void data)
	{
	/*
	* Currently this driver only support GP Complaint OPTEE based fTPM TA
	*/
	if ((ver->impl_id == TEE_IMPL_ID_OPTEE) &&
	(ver->gen_caps & TEE_GEN_CAP_GP))
	return 1;
	else
	return 0;
	}

	/**
	* ftpm_tee_probe() - initialize the fTPM
	* @pdev: the platform_device description.
	*
	* Return:
	* On success, 0. On failure, -errno.
	*/
	static int ftpm_tee_probe(struct device *dev)
	{
	int rc;
	struct tpm_chip *chip;
	struct ftpm_tee_private *pvt_data = NULL;
	struct tee_ioctl_open_session_arg sess_arg;

	pvt_data = devm_kzalloc(dev, sizeof(struct ftpm_tee_private),
	GFP_KERNEL);
	if (!pvt_data)
	return -ENOMEM;

	dev_set_drvdata(dev, pvt_data);

	/* Open context with TEE driver */
	pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL,
	NULL);
	if (IS_ERR(pvt_data->ctx)) {
	if (PTR_ERR(pvt_data->ctx) == -ENOENT)
	return -EPROBE_DEFER;
	dev_err(dev, "%s: tee_client_open_context failed\n", __func__);
	return PTR_ERR(pvt_data->ctx);
	}

	/* Open a session with fTPM TA */
	memset(&sess_arg, 0, sizeof(sess_arg));
	export_uuid(sess_arg.uuid, &ftpm_ta_uuid);
	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
	sess_arg.num_params = 0;

	rc = tee_client_open_session(pvt_data->ctx, &sess_arg, NULL);
	if ((rc < 0) \|\| (sess_arg.ret != 0)) {
	dev_err(dev, "%s: tee_client_open_session failed, err=%x\n",
	__func__, sess_arg.ret);
	rc = -EINVAL;
	goto out_tee_session;
	}
	pvt_data->session = sess_arg.session;

	/* Allocate dynamic shared memory with fTPM TA */
	pvt_data->shm = tee_shm_alloc_kernel_buf(pvt_data->ctx,
	MAX_COMMAND_SIZE +
	MAX_RESPONSE_SIZE);
	if (IS_ERR(pvt_data->shm)) {
	dev_err(dev, "%s: tee_shm_alloc_kernel_buf failed\n", __func__);
	rc = -ENOMEM;
	goto out_shm_alloc;
	}

	/* Allocate new struct tpm_chip instance */
	chip = tpm_chip_alloc(dev, &ftpm_tee_tpm_ops);
	if (IS_ERR(chip)) {
	dev_err(dev, "%s: tpm_chip_alloc failed\n", __func__);
	rc = PTR_ERR(chip);
	goto out_chip_alloc;
	}

	pvt_data->chip = chip;
	pvt_data->chip->flags \|= TPM_CHIP_FLAG_TPM2;

	/* Create a character device for the fTPM */
	rc = tpm_chip_register(pvt_data->chip);
	if (rc) {
	dev_err(dev, "%s: tpm_chip_register failed with rc=%d\n",
	__func__, rc);
	goto out_chip;
	}

	return 0;

	out_chip:
	put_device(&pvt_data->chip->dev);
	out_chip_alloc:
	tee_shm_free(pvt_data->shm);
	out_shm_alloc:
	tee_client_close_session(pvt_data->ctx, pvt_data->session);
	out_tee_session:
	tee_client_close_context(pvt_data->ctx);

	return rc;
	}

	static int ftpm_plat_tee_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;

	return ftpm_tee_probe(dev);
	}

	/**
	* ftpm_tee_remove() - remove the TPM device
	* @pdev: the platform_device description.
	*
	* Return:
	* 0 always.
	*/
	static int ftpm_tee_remove(struct device *dev)
	{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(dev);

	/* Release the chip */
	tpm_chip_unregister(pvt_data->chip);

	/* frees chip */
	put_device(&pvt_data->chip->dev);

	/* Free the shared memory pool */
	tee_shm_free(pvt_data->shm);

	/* close the existing session with fTPM TA*/
	tee_client_close_session(pvt_data->ctx, pvt_data->session);

	/* close the context with TEE driver */
	tee_client_close_context(pvt_data->ctx);

	/* memory allocated with devm_kzalloc() is freed automatically */

	return 0;
	}

	static int ftpm_plat_tee_remove(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;

	return ftpm_tee_remove(dev);
	}

	/**
	* ftpm_tee_shutdown() - shutdown the TPM device
	* @pdev: the platform_device description.
	*/
	static void ftpm_plat_tee_shutdown(struct platform_device *pdev)
	{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev);

	tee_shm_free(pvt_data->shm);
	tee_client_close_session(pvt_data->ctx, pvt_data->session);
	tee_client_close_context(pvt_data->ctx);
	}

	static const struct of_device_id of_ftpm_tee_ids[] = {
	{ .compatible = "microsoft,ftpm" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids);

	static struct platform_driver ftpm_tee_plat_driver = {
	.driver = {
	.name = "ftpm-tee",
	.of_match_table = of_match_ptr(of_ftpm_tee_ids),
	},
	.shutdown = ftpm_plat_tee_shutdown,
	.probe = ftpm_plat_tee_probe,
	.remove = ftpm_plat_tee_remove,
	};

	/* UUID of the fTPM TA */
	static const struct tee_client_device_id optee_ftpm_id_table[] = {
	{UUID_INIT(0xbc50d971, 0xd4c9, 0x42c4,
	0x82, 0xcb, 0x34, 0x3f, 0xb7, 0xf3, 0x78, 0x96)},
	{}
	};

	MODULE_DEVICE_TABLE(tee, optee_ftpm_id_table);

	static struct tee_client_driver ftpm_tee_driver = {
	.id_table = optee_ftpm_id_table,
	.driver = {
	.name = "optee-ftpm",
	.bus = &tee_bus_type,
	.probe = ftpm_tee_probe,
	.remove = ftpm_tee_remove,
	},
	};

	static int __init ftpm_mod_init(void)
	{
	int rc;

	rc = platform_driver_register(&ftpm_tee_plat_driver);
	if (rc)
	return rc;

	return driver_register(&ftpm_tee_driver.driver);
	}

	static void __exit ftpm_mod_exit(void)
	{
	platform_driver_unregister(&ftpm_tee_plat_driver);
	driver_unregister(&ftpm_tee_driver.driver);
	}

	module_init(ftpm_mod_init);
	module_exit(ftpm_mod_exit);

	MODULE_AUTHOR("Thirupathaiah Annapureddy <thiruan@microsoft.com>");
	MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE");
	MODULE_LICENSE("GPL v2");