[mirror_ubuntu-jammy-kernel.git] / drivers / char / tpm / tpm_ftpm_tee.c

// 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 platform_device *pdev)
{
	int rc;
	struct tpm_chip *chip;
	struct device *dev = &pdev->dev;
	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));
	memcpy(sess_arg.uuid, ftpm_ta_uuid.b, TEE_IOCTL_UUID_LEN);
	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(pvt_data->ctx,
				      MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE,
				      TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
	if (IS_ERR(pvt_data->shm)) {
		dev_err(dev, "%s: tee_shm_alloc 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;
}

/**
 * ftpm_tee_remove - remove the TPM device
 * @pdev: the platform_device description.
 *
 * Return:
 *	0 always.
 */
static int ftpm_tee_remove(struct platform_device *pdev)
{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->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 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_driver = {
	.driver = {
		.name = "ftpm-tee",
		.of_match_table = of_match_ptr(of_ftpm_tee_ids),
	},
	.probe = ftpm_tee_probe,
	.remove = ftpm_tee_remove,
};

module_platform_driver(ftpm_tee_driver);

MODULE_AUTHOR("Thirupathaiah Annapureddy <thiruan@microsoft.com>");
MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
09e57483 SL	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Copyright (C) Microsoft Corporation
	4	*
	5	* Implements a firmware TPM as described here:
	6	* https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
	7	*
	8	* A reference implementation is available here:
	9	* https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
	10	*/
	11
	12	#include <linux/acpi.h>
	13	#include <linux/of.h>
	14	#include <linux/of_platform.h>
	15	#include <linux/platform_device.h>
	16	#include <linux/tee_drv.h>
	17	#include <linux/tpm.h>
	18	#include <linux/uuid.h>
	19
	20	#include "tpm.h"
	21	#include "tpm_ftpm_tee.h"
	22
	23	/*
	24	* TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896
	25	*
	26	* Randomly generated, and must correspond to the GUID on the TA side.
	27	* Defined here in the reference implementation:
	28	* https://github.com/microsoft/ms-tpm-20-ref/blob/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM/include/fTPM.h#L42
	29	*/
	30	static const uuid_t ftpm_ta_uuid =
	31	UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4,
	32	0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96);
	33
	34	/**
	35	* ftpm_tee_tpm_op_recv - retrieve fTPM response.
	36	* @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h.
	37	* @buf: the buffer to store data.
	38	* @count: the number of bytes to read.
	39	*
	40	* Return:
	41	* In case of success the number of bytes received.
	42	* On failure, -errno.
	43	*/
	44	static int ftpm_tee_tpm_op_recv(struct tpm_chip chip, u8 buf, size_t count)
	45	{
	46	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
	47	size_t len;
	48
	49	len = pvt_data->resp_len;
	50	if (count < len) {
	51	dev_err(&chip->dev,
	52	"%s: Invalid size in recv: count=%zd, resp_len=%zd\n",
	53	__func__, count, len);
	54	return -EIO;
	55	}
	56
	57	memcpy(buf, pvt_data->resp_buf, len);
	58	pvt_data->resp_len = 0;
	59
	60	return len;
	61	}
	62
	63	/**
	64	* ftpm_tee_tpm_op_send - send TPM commands through the TEE shared memory.
65	* @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h
66	* @buf: the buffer to send.
67	* @len: the number of bytes to send.
68	*
69	* Return:
70	* In case of success, returns 0.
71	* On failure, -errno
72	*/
73	static int ftpm_tee_tpm_op_send(struct tpm_chip chip, u8 buf, size_t len)
74	{
75	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
76	size_t resp_len;
77	int rc;
78	u8 *temp_buf;
79	struct tpm_header *resp_header;
80	struct tee_ioctl_invoke_arg transceive_args;
81	struct tee_param command_params[4];
82	struct tee_shm *shm = pvt_data->shm;
83
84	if (len > MAX_COMMAND_SIZE) {
85	dev_err(&chip->dev,
86	"%s: len=%zd exceeds MAX_COMMAND_SIZE supported by fTPM TA\n",
87	__func__, len);
88	return -EIO;
89	}
90
91	memset(&transceive_args, 0, sizeof(transceive_args));
92	memset(command_params, 0, sizeof(command_params));
93	pvt_data->resp_len = 0;
94
95	/* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
96	transceive_args = (struct tee_ioctl_invoke_arg) {
97	.func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
98	.session = pvt_data->session,
99	.num_params = 4,
100	};
101
102	/* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
103	command_params[0] = (struct tee_param) {
104	.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT,
105	.u.memref = {
106	.shm = shm,
107	.size = len,
108	.shm_offs = 0,
109	},
110	};
111
112	temp_buf = tee_shm_get_va(shm, 0);
113	if (IS_ERR(temp_buf)) {
114	dev_err(&chip->dev, "%s: tee_shm_get_va failed for transmit\n",
115	__func__);
116	return PTR_ERR(temp_buf);
117	}
118	memset(temp_buf, 0, (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
119	memcpy(temp_buf, buf, len);
120
121	command_params[1] = (struct tee_param) {
122	.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
123	.u.memref = {
124	.shm = shm,
125	.size = MAX_RESPONSE_SIZE,
126	.shm_offs = MAX_COMMAND_SIZE,
127	},
128	};
129
130	rc = tee_client_invoke_func(pvt_data->ctx, &transceive_args,
131	command_params);
132	if ((rc < 0) \|\| (transceive_args.ret != 0)) {
133	dev_err(&chip->dev, "%s: SUBMIT_COMMAND invoke error: 0x%x\n",
134	__func__, transceive_args.ret);
135	return (rc < 0) ? rc : transceive_args.ret;
136	}
137
138	temp_buf = tee_shm_get_va(shm, command_params[1].u.memref.shm_offs);
139	if (IS_ERR(temp_buf)) {
140	dev_err(&chip->dev, "%s: tee_shm_get_va failed for receive\n",
141	__func__);
142	return PTR_ERR(temp_buf);
143	}
144
145	resp_header = (struct tpm_header *)temp_buf;
146	resp_len = be32_to_cpu(resp_header->length);
147
148	/* sanity check resp_len */
149	if (resp_len < TPM_HEADER_SIZE) {
150	dev_err(&chip->dev, "%s: tpm response header too small\n",
151	__func__);
152	return -EIO;
153	}
154	if (resp_len > MAX_RESPONSE_SIZE) {
155	dev_err(&chip->dev,
156	"%s: resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
157	__func__, resp_len);
158	return -EIO;
159	}
160
161	/* sanity checks look good, cache the response */
162	memcpy(pvt_data->resp_buf, temp_buf, resp_len);
163	pvt_data->resp_len = resp_len;
164
165	return 0;
166	}
167
168	static void ftpm_tee_tpm_op_cancel(struct tpm_chip *chip)
169	{
170	/* not supported */
171	}
172
173	static u8 ftpm_tee_tpm_op_status(struct tpm_chip *chip)
174	{
175	return 0;
176	}
177
178	static bool ftpm_tee_tpm_req_canceled(struct tpm_chip *chip, u8 status)
179	{
180	return 0;
181	}
182
183	static const struct tpm_class_ops ftpm_tee_tpm_ops = {
184	.flags = TPM_OPS_AUTO_STARTUP,
185	.recv = ftpm_tee_tpm_op_recv,
186	.send = ftpm_tee_tpm_op_send,
187	.cancel = ftpm_tee_tpm_op_cancel,
188	.status = ftpm_tee_tpm_op_status,
189	.req_complete_mask = 0,
190	.req_complete_val = 0,
191	.req_canceled = ftpm_tee_tpm_req_canceled,
192	};
193
194	/*
195	* Check whether this driver supports the fTPM TA in the TEE instance
196	* represented by the params (ver/data) to this function.
197	*/
198	static int ftpm_tee_match(struct tee_ioctl_version_data ver, const void data)
199	{
200	/*
201	* Currently this driver only support GP Complaint OPTEE based fTPM TA
202	*/
203	if ((ver->impl_id == TEE_IMPL_ID_OPTEE) &&
204	(ver->gen_caps & TEE_GEN_CAP_GP))
205	return 1;
206	else
207	return 0;
208	}
209
210	/**
211	* ftpm_tee_probe - initialize the fTPM
212	* @pdev: the platform_device description.
213	*
214	* Return:
215	* On success, 0. On failure, -errno.
216	*/
217	static int ftpm_tee_probe(struct platform_device *pdev)
218	{
219	int rc;
220	struct tpm_chip *chip;
221	struct device *dev = &pdev->dev;
222	struct ftpm_tee_private *pvt_data = NULL;
223	struct tee_ioctl_open_session_arg sess_arg;
224
225	pvt_data = devm_kzalloc(dev, sizeof(struct ftpm_tee_private),
226	GFP_KERNEL);
227	if (!pvt_data)
228	return -ENOMEM;
229
230	dev_set_drvdata(dev, pvt_data);
231
232	/* Open context with TEE driver */
233	pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL,
234	NULL);
235	if (IS_ERR(pvt_data->ctx)) {
236	if (PTR_ERR(pvt_data->ctx) == -ENOENT)
237	return -EPROBE_DEFER;
238	dev_err(dev, "%s: tee_client_open_context failed\n", __func__);
239	return PTR_ERR(pvt_data->ctx);
240	}
241
242	/* Open a session with fTPM TA */
243	memset(&sess_arg, 0, sizeof(sess_arg));
244	memcpy(sess_arg.uuid, ftpm_ta_uuid.b, TEE_IOCTL_UUID_LEN);
245	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
246	sess_arg.num_params = 0;
247
248	rc = tee_client_open_session(pvt_data->ctx, &sess_arg, NULL);
249	if ((rc < 0) \|\| (sess_arg.ret != 0)) {
250	dev_err(dev, "%s: tee_client_open_session failed, err=%x\n",
251	__func__, sess_arg.ret);
252	rc = -EINVAL;
253	goto out_tee_session;
254	}
255	pvt_data->session = sess_arg.session;
256
257	/* Allocate dynamic shared memory with fTPM TA */
258	pvt_data->shm = tee_shm_alloc(pvt_data->ctx,
259	MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE,
260	TEE_SHM_MAPPED \| TEE_SHM_DMA_BUF);
261	if (IS_ERR(pvt_data->shm)) {
262	dev_err(dev, "%s: tee_shm_alloc failed\n", __func__);
263	rc = -ENOMEM;
264	goto out_shm_alloc;
265	}
266
267	/* Allocate new struct tpm_chip instance */
268	chip = tpm_chip_alloc(dev, &ftpm_tee_tpm_ops);
269	if (IS_ERR(chip)) {
270	dev_err(dev, "%s: tpm_chip_alloc failed\n", __func__);
271	rc = PTR_ERR(chip);
272	goto out_chip_alloc;
273	}
274
275	pvt_data->chip = chip;
276	pvt_data->chip->flags \|= TPM_CHIP_FLAG_TPM2;
277
278	/* Create a character device for the fTPM */
279	rc = tpm_chip_register(pvt_data->chip);
280	if (rc) {
281	dev_err(dev, "%s: tpm_chip_register failed with rc=%d\n",
282	__func__, rc);
283	goto out_chip;
284	}
285
286	return 0;
287
288	out_chip:
289	put_device(&pvt_data->chip->dev);
290	out_chip_alloc:
291	tee_shm_free(pvt_data->shm);
292	out_shm_alloc:
293	tee_client_close_session(pvt_data->ctx, pvt_data->session);
294	out_tee_session:
295	tee_client_close_context(pvt_data->ctx);
296
297	return rc;
298	}
299
300	/**
301	* ftpm_tee_remove - remove the TPM device
302	* @pdev: the platform_device description.
303	*
304	* Return:
305	* 0 always.
306	*/
307	static int ftpm_tee_remove(struct platform_device *pdev)
308	{
309	struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev);
310
311	/* Release the chip */
312	tpm_chip_unregister(pvt_data->chip);
313
314	/* frees chip */
315	put_device(&pvt_data->chip->dev);
316
317	/* Free the shared memory pool */
318	tee_shm_free(pvt_data->shm);
319
320	/* close the existing session with fTPM TA*/
321	tee_client_close_session(pvt_data->ctx, pvt_data->session);
322
323	/* close the context with TEE driver */
324	tee_client_close_context(pvt_data->ctx);
325
326	/* memory allocated with devm_kzalloc() is freed automatically */
327
328	return 0;
329	}
330
331	static const struct of_device_id of_ftpm_tee_ids[] = {
332	{ .compatible = "microsoft,ftpm" },
333	{ }
334	};
335	MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids);
336
337	static struct platform_driver ftpm_tee_driver = {
338	.driver = {
339	.name = "ftpm-tee",
340	.of_match_table = of_match_ptr(of_ftpm_tee_ids),
341	},
342	.probe = ftpm_tee_probe,
343	.remove = ftpm_tee_remove,
344	};
345
346	module_platform_driver(ftpm_tee_driver);
347
348	MODULE_AUTHOR("Thirupathaiah Annapureddy <thiruan@microsoft.com>");
349	MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE");
350	MODULE_LICENSE("GPL v2");