11 files changed, 475 insertions, 48 deletions

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 88a3c06fc153..9c37047f4b56 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -164,6 +164,11 @@ config TCG_VTPM_PROXY
 	  /dev/vtpmX and a server-side file descriptor on which the vTPM
 	  can receive commands.
 
+config TCG_FTPM_TEE
+	tristate "TEE based fTPM Interface"
+	depends on TEE && OPTEE
+	help
+	  This driver proxies for firmware TPM running in TEE.
 
 source "drivers/char/tpm/st33zp24/Kconfig"
 endif # TCG_TPM
diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index a01c4cab902a..c354cdff9c62 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -33,3 +33,4 @@ obj-$(CONFIG_TCG_TIS_ST33ZP24) += st33zp24/
 obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
 obj-$(CONFIG_TCG_CRB) += tpm_crb.o
 obj-$(CONFIG_TCG_VTPM_PROXY) += tpm_vtpm_proxy.o
+obj-$(CONFIG_TCG_FTPM_TEE) += tpm_ftpm_tee.o
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index d47ad10a35fe..3d6d394a8661 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -77,6 +77,18 @@ static int tpm_go_idle(struct tpm_chip *chip)
 	return chip->ops->go_idle(chip);
 }
 
+static void tpm_clk_enable(struct tpm_chip *chip)
+{
+	if (chip->ops->clk_enable)
+		chip->ops->clk_enable(chip, true);
+}
+
+static void tpm_clk_disable(struct tpm_chip *chip)
+{
+	if (chip->ops->clk_enable)
+		chip->ops->clk_enable(chip, false);
+}
+
 /**
  * tpm_chip_start() - power on the TPM
  * @chip:	a TPM chip to use
@@ -89,13 +101,12 @@ int tpm_chip_start(struct tpm_chip *chip)
 {
 	int ret;
 
-	if (chip->ops->clk_enable)
-		chip->ops->clk_enable(chip, true);
+	tpm_clk_enable(chip);
 
 	if (chip->locality == -1) {
 		ret = tpm_request_locality(chip);
 		if (ret) {
-			chip->ops->clk_enable(chip, false);
+			tpm_clk_disable(chip);
 			return ret;
 		}
 	}
@@ -103,8 +114,7 @@ int tpm_chip_start(struct tpm_chip *chip)
 	ret = tpm_cmd_ready(chip);
 	if (ret) {
 		tpm_relinquish_locality(chip);
-		if (chip->ops->clk_enable)
-			chip->ops->clk_enable(chip, false);
+		tpm_clk_disable(chip);
 		return ret;
 	}
 
@@ -124,8 +134,7 @@ void tpm_chip_stop(struct tpm_chip *chip)
 {
 	tpm_go_idle(chip);
 	tpm_relinquish_locality(chip);
-	if (chip->ops->clk_enable)
-		chip->ops->clk_enable(chip, false);
+	tpm_clk_disable(chip);
 }
 EXPORT_SYMBOL_GPL(tpm_chip_stop);
 
@@ -278,12 +287,9 @@ static void tpm_devs_release(struct device *dev)
  * @dev: device to which the chip is associated.
  *
  * Issues a TPM2_Shutdown command prior to loss of power, as required by the
- * TPM 2.0 spec.
- * Then, calls bus- and device- specific shutdown code.
+ * TPM 2.0 spec. Then, calls bus- and device- specific shutdown code.
  *
- * XXX: This codepath relies on the fact that sysfs is not enabled for
- * TPM2: sysfs uses an implicit lock on chip->ops, so this could race if TPM2
- * has sysfs support enabled before TPM sysfs's implicit locking is fixed.
+ * Return: always 0 (i.e. success)
  */
 static int tpm_class_shutdown(struct device *dev)
 {
@@ -545,6 +551,20 @@ static int tpm_add_hwrng(struct tpm_chip *chip)
 	return hwrng_register(&chip->hwrng);
 }
 
+static int tpm_get_pcr_allocation(struct tpm_chip *chip)
+{
+	int rc;
+
+	rc = (chip->flags & TPM_CHIP_FLAG_TPM2) ?
+	     tpm2_get_pcr_allocation(chip) :
+	     tpm1_get_pcr_allocation(chip);
+
+	if (rc > 0)
+		return -ENODEV;
+
+	return rc;
+}
+
 /*
  * tpm_chip_register() - create a character device for the TPM chip
  * @chip: TPM chip to use.
@@ -564,6 +584,12 @@ int tpm_chip_register(struct tpm_chip *chip)
 	if (rc)
 		return rc;
 	rc = tpm_auto_startup(chip);
+	if (rc) {
+		tpm_chip_stop(chip);
+		return rc;
+	}
+
+	rc = tpm_get_pcr_allocation(chip);
 	tpm_chip_stop(chip);
 	if (rc)
 		return rc;
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1b4f95c13e00..d7a3888ad80f 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -320,18 +320,22 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 	if (!chip)
 		return -ENODEV;
 
-	for (i = 0; i < chip->nr_allocated_banks; i++)
-		if (digests[i].alg_id != chip->allocated_banks[i].alg_id)
-			return -EINVAL;
+	for (i = 0; i < chip->nr_allocated_banks; i++) {
+		if (digests[i].alg_id != chip->allocated_banks[i].alg_id) {
+			rc = EINVAL;
+			goto out;
+		}
+	}
 
 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
 		rc = tpm2_pcr_extend(chip, pcr_idx, digests);
-		tpm_put_ops(chip);
-		return rc;
+		goto out;
 	}
 
 	rc = tpm1_pcr_extend(chip, pcr_idx, digests[0].digest,
 			     "attempting extend a PCR value");
+
+out:
 	tpm_put_ops(chip);
 	return rc;
 }
@@ -354,14 +358,9 @@ int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
 	if (!chip)
 		return -ENODEV;
 
-	rc = tpm_buf_init(&buf, 0, 0);
-	if (rc)
-		goto out;
-
-	memcpy(buf.data, cmd, buflen);
+	buf.data = cmd;
 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to a send a command");
-	tpm_buf_destroy(&buf);
-out:
+
 	tpm_put_ops(chip);
 	return rc;
 }
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index d9caedda075b..edfa89160010 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -329,16 +329,9 @@ static const struct attribute_group tpm_dev_group = {
 
 void tpm_sysfs_add_device(struct tpm_chip *chip)
 {
-	/* XXX: If you wish to remove this restriction, you must first update
-	 * tpm_sysfs to explicitly lock chip->ops.
-	 */
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		return;
 
-	/* The sysfs routines rely on an implicit tpm_try_get_ops, device_del
-	 * is called before ops is null'd and the sysfs core synchronizes this
-	 * removal so that no callbacks are running or can run again
-	 */
 	WARN_ON(chip->groups_cnt != 0);
 	chip->groups[chip->groups_cnt++] = &tpm_dev_group;
 }
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index e503ffc3aa39..a7fea3e0ca86 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -394,6 +394,7 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf);
 ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		    const char *desc, size_t min_cap_length);
 int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max);
+int tpm1_get_pcr_allocation(struct tpm_chip *chip);
 unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
 int tpm_pm_suspend(struct device *dev);
 int tpm_pm_resume(struct device *dev);
@@ -449,6 +450,7 @@ int tpm2_unseal_trusted(struct tpm_chip *chip,
 ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,
 			u32 *value, const char *desc);
 
+ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip);
 int tpm2_auto_startup(struct tpm_chip *chip);
 void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type);
 unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index faacbe1ffa1a..149e953ca369 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -699,18 +699,6 @@ int tpm1_auto_startup(struct tpm_chip *chip)
 		goto out;
 	}
 
-	chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
-					GFP_KERNEL);
-	if (!chip->allocated_banks) {
-		rc = -ENOMEM;
-		goto out;
-	}
-
-	chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
-	chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
-	chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
-	chip->nr_allocated_banks = 1;
-
 	return rc;
 out:
 	if (rc > 0)
@@ -779,3 +767,27 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 	return rc;
 }
 
+/**
+ * tpm1_get_pcr_allocation() - initialize the allocated bank
+ * @chip: TPM chip to use.
+ *
+ * The function initializes the SHA1 allocated bank to extend PCR
+ *
+ * Return:
+ * * 0 on success,
+ * * < 0 on error.
+ */
+int tpm1_get_pcr_allocation(struct tpm_chip *chip)
+{
+	chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
+					GFP_KERNEL);
+	if (!chip->allocated_banks)
+		return -ENOMEM;
+
+	chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
+	chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
+	chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
+	chip->nr_allocated_banks = 1;
+
+	return 0;
+}
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index d103545e4055..ba9acae83bff 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -840,7 +840,7 @@ struct tpm2_pcr_selection {
 	u8  pcr_select[3];
 } __packed;
 
-static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
+ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 {
 	struct tpm2_pcr_selection pcr_selection;
 	struct tpm_buf buf;
@@ -1040,10 +1040,6 @@ int tpm2_auto_startup(struct tpm_chip *chip)
 			goto out;
 	}
 
-	rc = tpm2_get_pcr_allocation(chip);
-	if (rc)
-		goto out;
-
 	rc = tpm2_get_cc_attrs_tbl(chip);
 
 out:
diff --git a/drivers/char/tpm/tpm_ftpm_tee.c b/drivers/char/tpm/tpm_ftpm_tee.c
new file mode 100644
index 000000000000..6640a14dbe48
--- /dev/null
+++ b/drivers/char/tpm/tpm_ftpm_tee.c
@@ -0,0 +1,350 @@
+// 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");
diff --git a/drivers/char/tpm/tpm_ftpm_tee.h b/drivers/char/tpm/tpm_ftpm_tee.h
new file mode 100644
index 000000000000..f98daa7bf68c
--- /dev/null
+++ b/drivers/char/tpm/tpm_ftpm_tee.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation
+ */
+
+#ifndef __TPM_FTPM_TEE_H__
+#define __TPM_FTPM_TEE_H__
+
+#include <linux/tee_drv.h>
+#include <linux/tpm.h>
+#include <linux/uuid.h>
+
+/* The TAFs ID implemented in this TA */
+#define FTPM_OPTEE_TA_SUBMIT_COMMAND  (0)
+#define FTPM_OPTEE_TA_EMULATE_PPI     (1)
+
+/* max. buffer size supported by fTPM  */
+#define MAX_COMMAND_SIZE       4096
+#define MAX_RESPONSE_SIZE      4096
+
+/**
+ * struct ftpm_tee_private - fTPM's private data
+ * @chip:     struct tpm_chip instance registered with tpm framework.
+ * @state:    internal state
+ * @session:  fTPM TA session identifier.
+ * @resp_len: cached response buffer length.
+ * @resp_buf: cached response buffer.
+ * @ctx:      TEE context handler.
+ * @shm:      Memory pool shared with fTPM TA in TEE.
+ */
+struct ftpm_tee_private {
+	struct tpm_chip *chip;
+	u32 session;
+	size_t resp_len;
+	u8 resp_buf[MAX_RESPONSE_SIZE];
+	struct tee_context *ctx;
+	struct tee_shm *shm;
+};
+
+#endif /* __TPM_FTPM_TEE_H__ */
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index c3181ea9f271..270f43acbb77 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -980,6 +980,8 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 			goto out_err;
 		}
 
+		tpm_chip_start(chip);
+		chip->flags |= TPM_CHIP_FLAG_IRQ;
 		if (irq) {
 			tpm_tis_probe_irq_single(chip, intmask, IRQF_SHARED,
 						 irq);
@@ -989,6 +991,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 		} else {
 			tpm_tis_probe_irq(chip, intmask);
 		}
+		tpm_chip_stop(chip);
 	}
 
 	rc = tpm_chip_register(chip);