Re: [PATCH v2 2/3] tee: tstee: Add Trusted Services TEE driver

[Balint Dobszay]

On 27 Feb 2024, at 8:08, Sumit Garg wrote:

> On Fri, 23 Feb 2024 at 15:22, Balint Dobszay <balint.dobszay@xxxxxxx> wrote:
>>
>> The Trusted Services project provides a framework for developing and
>> deploying device Root of Trust services in FF-A Secure Partitions. The
>> FF-A SPs are accessible through the FF-A driver, but this doesn't
>> provide a user space interface. The goal of this TEE driver is to make
>> Trusted Services SPs accessible for user space clients.
>>
>> All TS SPs have the same FF-A UUID, it identifies the RPC protocol used
>> by TS. A TS SP can host one or more services, a service is identified by
>> its service UUID. The same type of service cannot be present twice in
>> the same SP. During SP boot each service in an SP is assigned an
>> interface ID, this is just a short ID to simplify message addressing.
>> There is 1:1 mapping between TS SPs and TEE devices, i.e. a separate TEE
>> device is registered for each TS SP. This is required since contrary to
>> the generic TEE design where memory is shared with the whole TEE
>> implementation, in case of FF-A, memory is shared with a specific SP. A
>> user space client has to be able to separately share memory with each SP
>> based on its endpoint ID.
>>
>> Signed-off-by: Balint Dobszay <balint.dobszay@xxxxxxx>
>> ---
>>  drivers/tee/Kconfig               |   1 +
>>  drivers/tee/Makefile              |   1 +
>>  drivers/tee/tstee/Kconfig         |  11 +
>>  drivers/tee/tstee/Makefile        |   3 +
>>  drivers/tee/tstee/core.c          | 490 ++++++++++++++++++++++++++++++
>>  drivers/tee/tstee/tstee_private.h |  94 ++++++
>>  include/uapi/linux/tee.h          |   1 +
>>  7 files changed, 601 insertions(+)
>>  create mode 100644 drivers/tee/tstee/Kconfig
>>  create mode 100644 drivers/tee/tstee/Makefile
>>  create mode 100644 drivers/tee/tstee/core.c
>>  create mode 100644 drivers/tee/tstee/tstee_private.h
>>
>> diff --git a/drivers/tee/Kconfig b/drivers/tee/Kconfig
>> index 73a147202e88..61b507c18780 100644
>> --- a/drivers/tee/Kconfig
>> +++ b/drivers/tee/Kconfig
>> @@ -15,5 +15,6 @@ if TEE
>>
>>  source "drivers/tee/optee/Kconfig"
>>  source "drivers/tee/amdtee/Kconfig"
>> +source "drivers/tee/tstee/Kconfig"
>>
>>  endif
>> diff --git a/drivers/tee/Makefile b/drivers/tee/Makefile
>> index 68da044afbfa..5488cba30bd2 100644
>> --- a/drivers/tee/Makefile
>> +++ b/drivers/tee/Makefile
>> @@ -5,3 +5,4 @@ tee-objs += tee_shm.o
>>  tee-objs += tee_shm_pool.o
>>  obj-$(CONFIG_OPTEE) += optee/
>>  obj-$(CONFIG_AMDTEE) += amdtee/
>> +obj-$(CONFIG_ARM_TSTEE) += tstee/
>> diff --git a/drivers/tee/tstee/Kconfig b/drivers/tee/tstee/Kconfig
>> new file mode 100644
>> index 000000000000..d32f91d47398
>> --- /dev/null
>> +++ b/drivers/tee/tstee/Kconfig
>> @@ -0,0 +1,11 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +config ARM_TSTEE
>> +       tristate "Arm Trusted Services TEE driver"
>> +       depends on ARM_FFA_TRANSPORT
>> +       default n
>> +       help
>> +         The Trusted Services project provides a framework for developing and
>> +         deploying device Root of Trust services in FF-A Secure Partitions.
>> +         This driver provides an interface to make Trusted Services Secure
>> +         Partitions accessible for user space clients, since the FF-A driver
>> +         doesn't implement a user space interface directly.
>> diff --git a/drivers/tee/tstee/Makefile b/drivers/tee/tstee/Makefile
>> new file mode 100644
>> index 000000000000..5227020ebd30
>> --- /dev/null
>> +++ b/drivers/tee/tstee/Makefile
>> @@ -0,0 +1,3 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +arm-tstee-objs := core.o
>> +obj-$(CONFIG_ARM_TSTEE) = arm-tstee.o
>> diff --git a/drivers/tee/tstee/core.c b/drivers/tee/tstee/core.c
>> new file mode 100644
>> index 000000000000..2932be017dbe
>> --- /dev/null
>> +++ b/drivers/tee/tstee/core.c
>> @@ -0,0 +1,490 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2023, Arm Limited
>> + */
>> +
>> +#define DRIVER_NAME "Arm TSTEE"
>> +#define pr_fmt(fmt) DRIVER_NAME ": " fmt
>> +
>> +#include <linux/arm_ffa.h>
>> +#include <linux/err.h>
>> +#include <linux/errno.h>
>> +#include <linux/kernel.h>
>> +#include <linux/limits.h>
>> +#include <linux/list.h>
>> +#include <linux/mm.h>
>> +#include <linux/module.h>
>> +#include <linux/scatterlist.h>
>> +#include <linux/slab.h>
>> +#include <linux/stat.h>
>> +#include <linux/tee_drv.h>
>> +#include <linux/types.h>
>> +#include <linux/uaccess.h>
>> +
>> +#include "tstee_private.h"
>> +
>> +#define FFA_DIRECT_REQ_ARG_NUM 5
>> +#define FFA_INVALID_MEM_HANDLE U64_MAX
>> +
>> +static void arg_list_to_ffa_data(const u32 *args,
>> +                                struct ffa_send_direct_data *data)
>> +{
>> +       data->data0 = args[0];
>> +       data->data1 = args[1];
>> +       data->data2 = args[2];
>> +       data->data3 = args[3];
>> +       data->data4 = args[4];
>> +}
>> +
>> +static void arg_list_from_ffa_data(const struct ffa_send_direct_data *data,
>> +                                  u32 *args)
>> +{
>> +       args[0] = lower_32_bits(data->data0);
>> +       args[1] = lower_32_bits(data->data1);
>> +       args[2] = lower_32_bits(data->data2);
>> +       args[3] = lower_32_bits(data->data3);
>> +       args[4] = lower_32_bits(data->data4);
>> +}
>> +
>> +static void tstee_get_version(struct tee_device *teedev,
>> +                             struct tee_ioctl_version_data *vers)
>> +{
>> +       struct tstee *tstee = tee_get_drvdata(teedev);
>> +       struct tee_ioctl_version_data v = {
>> +               .impl_id = TEE_IMPL_ID_TSTEE,
>> +               /* FF-A endpoint ID only uses the lower 16 bits */
>> +               .impl_caps = lower_16_bits(tstee->ffa_dev->vm_id),
>> +               .gen_caps = 0,
>> +       };
>> +
>> +       *vers = v;
>> +}
>> +
>> +static int tstee_open(struct tee_context *ctx)
>> +{
>> +       struct ts_context_data *ctxdata;
>> +
>> +       ctxdata = kzalloc(sizeof(*ctxdata), GFP_KERNEL);
>> +       if (!ctxdata)
>> +               return -ENOMEM;
>> +
>> +       mutex_init(&ctxdata->mutex);
>> +       xa_init_flags(&ctxdata->sess_list, XA_FLAGS_ALLOC);
>> +
>> +       ctx->data = ctxdata;
>> +
>> +       return 0;
>> +}
>> +
>> +static void tstee_release(struct tee_context *ctx)
>> +{
>> +       struct ts_context_data *ctxdata = ctx->data;
>> +       struct ts_session *sess;
>> +       unsigned long idx;
>> +
>> +       if (!ctxdata)
>> +               return;
>> +
>> +       xa_for_each(&ctxdata->sess_list, idx, sess) {
>> +               xa_erase(&ctxdata->sess_list, idx);
>> +               kfree(sess);
>> +       }
>> +
>> +       xa_destroy(&ctxdata->sess_list);
>> +       mutex_destroy(&ctxdata->mutex);
>> +
>> +       kfree(ctxdata);
>> +       ctx->data = NULL;
>> +}
>> +
>> +static int tstee_open_session(struct tee_context *ctx,
>> +                             struct tee_ioctl_open_session_arg *arg,
>> +                             struct tee_param *param __always_unused)
>> +{
>> +       struct tstee *tstee = tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev = tstee->ffa_dev;
>> +       struct ts_context_data *ctxdata = ctx->data;
>> +       struct ffa_send_direct_data ffa_data;
>> +       struct ts_session *sess = NULL;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] = {};
>> +       u32 sess_id;
>> +       int rc;
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =
>> +               TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFACE_ID,
>> +                                             TS_RPC_OP_SERVICE_INFO);
>> +
>> +       memcpy(ffa_args + TS_RPC_SERVICE_INFO_UUID0, arg->uuid, UUID_SIZE);
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc = ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_data);
>> +       if (rc)
>> +               return rc;
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_SERVICE_INFO_RPC_STATUS] != TS_RPC_OK)
>> +               return -ENODEV;
>> +
>> +       if (ffa_args[TS_RPC_SERVICE_INFO_IFACE] > U8_MAX)
>> +               return -EINVAL;
>> +
>> +       sess = kzalloc(sizeof(*sess), GFP_KERNEL);
>> +       if (!sess)
>> +               return -ENOMEM;
>> +
>> +       sess->iface_id = ffa_args[TS_RPC_SERVICE_INFO_IFACE];
>> +
>> +       rc = xa_alloc(&ctxdata->sess_list, &sess_id, sess, xa_limit_32b,
>> +                     GFP_KERNEL);
>> +       if (rc) {
>> +               kfree(sess);
>> +               return rc;
>> +       }
>> +
>> +       arg->session = sess_id;
>> +       arg->ret = 0;
>> +
>> +       return 0;
>> +}
>> +
>> +static int tstee_close_session(struct tee_context *ctx, u32 session)
>> +{
>> +       struct ts_context_data *ctxdata = ctx->data;
>> +       struct ts_session *sess;
>> +
>> +       mutex_lock(&ctxdata->mutex);
>> +       sess = xa_erase(&ctxdata->sess_list, session);
>> +       mutex_unlock(&ctxdata->mutex);
>> +       if (!sess)
>> +               return -EINVAL;
>> +
>> +       kfree(sess);
>> +
>> +       return 0;
>> +}
>> +
>> +static int tstee_invoke_func(struct tee_context *ctx,
>> +                            struct tee_ioctl_invoke_arg *arg,
>> +                            struct tee_param *param)
>> +{
>> +       struct tstee *tstee = tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev = tstee->ffa_dev;
>> +       struct ts_context_data *ctxdata = ctx->data;
>> +       struct ffa_send_direct_data ffa_data;
>> +       struct tee_shm *shm = NULL;
>> +       struct ts_session *sess;
>> +       u32 req_len, ffa_args[FFA_DIRECT_REQ_ARG_NUM] = {};
>> +       int shm_id, rc;
>> +       u8 iface_id;
>> +       u64 handle;
>> +       u16 opcode;
>> +
>> +       mutex_lock(&ctxdata->mutex);
>> +       sess = xa_load(&ctxdata->sess_list, arg->session);
>> +
>> +       /*
>> +        * Do this while holding the mutex to make sure that the session wasn't
>> +        * closed meanwhile
>> +        */
>> +       if (sess)
>> +               iface_id = sess->iface_id;
>> +
>> +       mutex_unlock(&ctxdata->mutex);
>> +       if (!sess)
>> +               return -EINVAL;
>> +
>
> We can drop usage of mutex here and other places via reusing
> xa_lock(), something like below should work:
>
>         xa_lock(&ctxdata->sess_list);
>
>         sess = xa_load(&ctxdata->sess_list, arg->session);
>         if (sess)
>                 iface_id = sess->iface_id;
>
>         xa_unlock(&ctxdata->sess_list);

Good point, I'll refactor according to your suggestion.

Regards,
Balint

>> +       opcode = lower_16_bits(arg->func);
>> +       shm_id = lower_32_bits(param[0].u.value.a);
>> +       req_len = lower_32_bits(param[0].u.value.b);
>> +
>> +       if (shm_id != 0) {
>> +               shm = tee_shm_get_from_id(ctx, shm_id);
>> +               if (IS_ERR(shm))
>> +                       return PTR_ERR(shm);
>> +
>> +               if (shm->size < req_len) {
>> +                       pr_err("request doesn't fit into shared memory buffer\n");
>> +                       rc = -EINVAL;
>> +                       goto out;
>> +               }
>> +
>> +               handle = shm->sec_world_id;
>> +       } else {
>> +               handle = FFA_INVALID_MEM_HANDLE;
>> +       }
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] = TS_RPC_CTRL_PACK_IFACE_OPCODE(iface_id,
>> +                                                                 opcode);
>> +       ffa_args[TS_RPC_SERVICE_MEM_HANDLE_LSW] = lower_32_bits(handle);
>> +       ffa_args[TS_RPC_SERVICE_MEM_HANDLE_MSW] = upper_32_bits(handle);
>> +       ffa_args[TS_RPC_SERVICE_REQ_LEN] = req_len;
>> +       ffa_args[TS_RPC_SERVICE_CLIENT_ID] = 0;
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc = ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_data);
>> +       if (rc)
>> +               goto out;
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_SERVICE_RPC_STATUS] != TS_RPC_OK) {
>> +               pr_err("invoke_func rpc status: %d\n",
>> +                      ffa_args[TS_RPC_SERVICE_RPC_STATUS]);
>> +               rc = -EINVAL;
>> +               goto out;
>> +       }
>> +
>> +       arg->ret = ffa_args[TS_RPC_SERVICE_STATUS];
>> +       if (shm && shm->size >= ffa_args[TS_RPC_SERVICE_RESP_LEN])
>> +               param[0].u.value.a = ffa_args[TS_RPC_SERVICE_RESP_LEN];
>> +
>> +out:
>> +       if (shm)
>> +               tee_shm_put(shm);
>> +
>> +       return rc;
>> +}
>> +
>> +static int tstee_shm_register(struct tee_context *ctx, struct tee_shm *shm,
>> +                             struct page **pages, size_t num_pages,
>> +                             unsigned long start __always_unused)
>> +{
>> +       struct tstee *tstee = tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev = tstee->ffa_dev;
>> +       struct ffa_mem_region_attributes mem_attr = {
>> +               .receiver = tstee->ffa_dev->vm_id,
>> +               .attrs = FFA_MEM_RW,
>> +               .flag = 0,
>> +       };
>> +       struct ffa_mem_ops_args mem_args = {
>> +               .attrs = &mem_attr,
>> +               .use_txbuf = true,
>> +               .nattrs = 1,
>> +               .flags = 0,
>> +       };
>> +       struct ffa_send_direct_data ffa_data;
>> +       struct sg_table sgt;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] = {};
>> +       int rc;
>> +
>> +       rc = sg_alloc_table_from_pages(&sgt, pages, num_pages, 0,
>> +                                      num_pages * PAGE_SIZE, GFP_KERNEL);
>> +       if (rc)
>> +               return rc;
>> +
>> +       mem_args.sg = sgt.sgl;
>> +       rc = ffa_dev->ops->mem_ops->memory_share(&mem_args);
>> +       sg_free_table(&sgt);
>> +       if (rc)
>> +               return rc;
>> +
>> +       shm->sec_world_id = mem_args.g_handle;
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =
>> +                       TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFACE_ID,
>> +                                                     TS_RPC_OP_RETRIEVE_MEM);
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_HANDLE_LSW] =
>> +                       lower_32_bits(shm->sec_world_id);
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_HANDLE_MSW] =
>> +                       upper_32_bits(shm->sec_world_id);
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_TAG_LSW] = 0;
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_TAG_MSW] = 0;
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc = ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_data);
>> +       if (rc) {
>> +               (void)ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_world_id,
>> +                                                           0);
>> +               return rc;
>> +       }
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_RETRIEVE_MEM_RPC_STATUS] != TS_RPC_OK) {
>> +               pr_err("shm_register rpc status: %d\n",
>> +                      ffa_args[TS_RPC_RETRIEVE_MEM_RPC_STATUS]);
>> +               ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_world_id, 0);
>> +               return -EINVAL;
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static int tstee_shm_unregister(struct tee_context *ctx, struct tee_shm *shm)
>> +{
>> +       struct tstee *tstee = tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev = tstee->ffa_dev;
>> +       struct ffa_send_direct_data ffa_data;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] = {};
>> +       int rc;
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =
>> +                       TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFACE_ID,
>> +                                                     TS_RPC_OP_RELINQ_MEM);
>> +       ffa_args[TS_RPC_RELINQ_MEM_HANDLE_LSW] =
>> +                       lower_32_bits(shm->sec_world_id);
>> +       ffa_args[TS_RPC_RELINQ_MEM_HANDLE_MSW] =
>> +                       upper_32_bits(shm->sec_world_id);
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc = ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_data);
>> +       if (rc)
>> +               return rc;
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_RELINQ_MEM_RPC_STATUS] != TS_RPC_OK) {
>> +               pr_err("shm_unregister rpc status: %d\n",
>> +                      ffa_args[TS_RPC_RELINQ_MEM_RPC_STATUS]);
>> +               return -EINVAL;
>> +       }
>> +
>> +       rc = ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_world_id, 0);
>> +
>> +       return rc;
>> +}
>> +
>> +static const struct tee_driver_ops tstee_ops = {
>> +       .get_version = tstee_get_version,
>> +       .open = tstee_open,
>> +       .release = tstee_release,
>> +       .open_session = tstee_open_session,
>> +       .close_session = tstee_close_session,
>> +       .invoke_func = tstee_invoke_func,
>> +       .shm_register = tstee_shm_register,
>> +       .shm_unregister = tstee_shm_unregister,
>> +};
>> +
>> +static const struct tee_desc tstee_desc = {
>> +       .name = "tstee-clnt",
>> +       .ops = &tstee_ops,
>> +       .owner = THIS_MODULE,
>> +};
>> +
>> +static int pool_op_alloc(struct tee_shm_pool *pool, struct tee_shm *shm,
>> +                        size_t size, size_t align)
>> +{
>> +       return tee_shm_pool_op_alloc_helper(pool, shm, size, align,
>> +                                           tstee_shm_register);
>> +}
>> +
>> +static void pool_op_free(struct tee_shm_pool *pool, struct tee_shm *shm)
>> +{
>> +       tee_shm_pool_op_free_helper(pool, shm, tstee_shm_unregister);
>> +}
>> +
>> +static void pool_op_destroy_pool(struct tee_shm_pool *pool)
>> +{
>> +       kfree(pool);
>> +}
>> +
>> +static const struct tee_shm_pool_ops pool_ops = {
>> +       .alloc = pool_op_alloc,
>> +       .free = pool_op_free,
>> +       .destroy_pool = pool_op_destroy_pool,
>> +};
>> +
>> +static struct tee_shm_pool *tstee_create_shm_pool(void)
>> +{
>> +       struct tee_shm_pool *pool = kzalloc(sizeof(*pool), GFP_KERNEL);
>> +
>> +       if (!pool)
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       pool->ops = &pool_ops;
>> +
>> +       return pool;
>> +}
>> +
>> +static bool tstee_check_rpc_compatible(struct ffa_device *ffa_dev)
>> +{
>> +       struct ffa_send_direct_data ffa_data;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] = {};
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =
>> +                       TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFACE_ID,
>> +                                                     TS_RPC_OP_GET_VERSION);
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       if (ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_data))
>> +               return false;
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       return ffa_args[TS_RPC_GET_VERSION_RESP] == TS_RPC_PROTOCOL_VERSION;
>> +}
>> +
>> +static int tstee_probe(struct ffa_device *ffa_dev)
>> +{
>> +       struct tstee *tstee;
>> +       int rc;
>> +
>> +       ffa_dev->ops->msg_ops->mode_32bit_set(ffa_dev);
>> +
>> +       if (!tstee_check_rpc_compatible(ffa_dev))
>> +               return -EINVAL;
>> +
>> +       tstee = kzalloc(sizeof(*tstee), GFP_KERNEL);
>> +       if (!tstee)
>> +               return -ENOMEM;
>> +
>> +       tstee->ffa_dev = ffa_dev;
>> +
>> +       tstee->pool = tstee_create_shm_pool();
>> +       if (IS_ERR(tstee->pool)) {
>> +               rc = PTR_ERR(tstee->pool);
>> +               tstee->pool = NULL;
>> +               goto err_free_tstee;
>> +       }
>> +
>> +       tstee->teedev = tee_device_alloc(&tstee_desc, NULL, tstee->pool, tstee);
>> +       if (IS_ERR(tstee->teedev)) {
>> +               rc = PTR_ERR(tstee->teedev);
>> +               tstee->teedev = NULL;
>> +               goto err_free_pool;
>> +       }
>> +
>> +       rc = tee_device_register(tstee->teedev);
>> +       if (rc)
>> +               goto err_unreg_teedev;
>> +
>> +       ffa_dev_set_drvdata(ffa_dev, tstee);
>> +
>> +       return 0;
>> +
>> +err_unreg_teedev:
>> +       tee_device_unregister(tstee->teedev);
>> +err_free_pool:
>> +       tee_shm_pool_free(tstee->pool);
>> +err_free_tstee:
>> +       kfree(tstee);
>> +       return rc;
>> +}
>> +
>> +static void tstee_remove(struct ffa_device *ffa_dev)
>> +{
>> +       struct tstee *tstee = ffa_dev->dev.driver_data;
>> +
>> +       tee_device_unregister(tstee->teedev);
>> +       tee_shm_pool_free(tstee->pool);
>> +       kfree(tstee);
>> +}
>> +
>> +static const struct ffa_device_id tstee_device_ids[] = {
>> +       /* TS RPC protocol UUID: bdcd76d7-825e-4751-963b-86d4f84943ac */
>> +       { TS_RPC_UUID },
>> +       {}
>> +};
>> +
>> +static struct ffa_driver tstee_driver = {
>> +       .name = "arm_tstee",
>> +       .probe = tstee_probe,
>> +       .remove = tstee_remove,
>> +       .id_table = tstee_device_ids,
>> +};
>> +
>> +module_ffa_driver(tstee_driver);
>> +
>> +MODULE_AUTHOR("Balint Dobszay <balint.dobszay@xxxxxxx>");
>> +MODULE_DESCRIPTION("Arm Trusted Services TEE driver");
>> +MODULE_LICENSE("GPL");
>> diff --git a/drivers/tee/tstee/tstee_private.h b/drivers/tee/tstee/tstee_private.h
>> new file mode 100644
>> index 000000000000..6d24cf0dbbc2
>> --- /dev/null
>> +++ b/drivers/tee/tstee/tstee_private.h
>> @@ -0,0 +1,94 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (c) 2023, Arm Limited
>> + */
>> +
>> +#ifndef TSTEE_PRIVATE_H
>> +#define TSTEE_PRIVATE_H
>> +
>> +#include <linux/arm_ffa.h>
>> +#include <linux/bitops.h>
>> +#include <linux/tee_drv.h>
>> +#include <linux/types.h>
>> +#include <linux/uuid.h>
>> +#include <linux/xarray.h>
>> +
>> +/*
>> + * The description of the ABI implemented in this file is available at
>> + * https://trusted-services.readthedocs.io/en/v1.0.0/developer/service-access-protocols.html#abi
>> + */
>> +
>> +/* UUID of this protocol */
>> +#define TS_RPC_UUID UUID_INIT(0xbdcd76d7, 0x825e, 0x4751, \
>> +                             0x96, 0x3b, 0x86, 0xd4, 0xf8, 0x49, 0x43, 0xac)
>> +
>> +/* Protocol version*/
>> +#define TS_RPC_PROTOCOL_VERSION                (1)
>> +
>> +/* Status codes */
>> +#define TS_RPC_OK                      (0)
>> +
>> +/* RPC control register */
>> +#define TS_RPC_CTRL_REG                        (0)
>> +#define OPCODE_MASK                    GENMASK(15, 0)
>> +#define IFACE_ID_MASK                  GENMASK(23, 16)
>> +#define TS_RPC_CTRL_OPCODE(x)          ((u16)(FIELD_GET(OPCODE_MASK, (x))))
>> +#define TS_RPC_CTRL_IFACE_ID(x)                ((u8)(FIELD_GET(IFACE_ID_MASK, (x))))
>> +#define TS_RPC_CTRL_PACK_IFACE_OPCODE(i, o)    \
>> +       (FIELD_PREP(IFACE_ID_MASK, (i)) | FIELD_PREP(OPCODE_MASK, (o)))
>> +#define TS_RPC_CTRL_SAP_RC             BIT(30)
>> +#define TS_RPC_CTRL_SAP_ERR            BIT(31)
>> +
>> +/* Interface ID for RPC management operations */
>> +#define TS_RPC_MGMT_IFACE_ID           (0xff)
>> +
>> +/* Management calls */
>> +#define TS_RPC_OP_GET_VERSION          (0x0000)
>> +#define TS_RPC_GET_VERSION_RESP                (1)
>> +
>> +#define TS_RPC_OP_RETRIEVE_MEM         (0x0001)
>> +#define TS_RPC_RETRIEVE_MEM_HANDLE_LSW (1)
>> +#define TS_RPC_RETRIEVE_MEM_HANDLE_MSW (2)
>> +#define TS_RPC_RETRIEVE_MEM_TAG_LSW    (3)
>> +#define TS_RPC_RETRIEVE_MEM_TAG_MSW    (4)
>> +#define TS_RPC_RETRIEVE_MEM_RPC_STATUS (1)
>> +
>> +#define TS_RPC_OP_RELINQ_MEM           (0x0002)
>> +#define TS_RPC_RELINQ_MEM_HANDLE_LSW   (1)
>> +#define TS_RPC_RELINQ_MEM_HANDLE_MSW   (2)
>> +#define TS_RPC_RELINQ_MEM_RPC_STATUS   (1)
>> +
>> +#define TS_RPC_OP_SERVICE_INFO         (0x0003)
>> +#define TS_RPC_SERVICE_INFO_UUID0      (1)
>> +#define TS_RPC_SERVICE_INFO_UUID1      (2)
>> +#define TS_RPC_SERVICE_INFO_UUID2      (3)
>> +#define TS_RPC_SERVICE_INFO_UUID3      (4)
>> +#define TS_RPC_SERVICE_INFO_RPC_STATUS (1)
>> +#define TS_RPC_SERVICE_INFO_IFACE      (2)
>> +
>> +/* Service call */
>> +#define TS_RPC_SERVICE_MEM_HANDLE_LSW  (1)
>> +#define TS_RPC_SERVICE_MEM_HANDLE_MSW  (2)
>> +#define TS_RPC_SERVICE_REQ_LEN         (3)
>> +#define TS_RPC_SERVICE_CLIENT_ID       (4)
>> +#define TS_RPC_SERVICE_RPC_STATUS      (1)
>> +#define TS_RPC_SERVICE_STATUS          (2)
>> +#define TS_RPC_SERVICE_RESP_LEN                (3)
>> +
>> +struct tstee {
>> +       struct ffa_device *ffa_dev;
>> +       struct tee_device *teedev;
>> +       struct tee_shm_pool *pool;
>> +};
>> +
>> +struct ts_session {
>> +       u8 iface_id;
>> +};
>> +
>> +struct ts_context_data {
>> +       struct xarray sess_list;
>> +       /* Serializes access to the session list */
>> +       struct mutex mutex;
>> +};
>> +
>> +#endif /* TSTEE_PRIVATE_H */
>> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
>> index 23e57164693c..d0430bee8292 100644
>> --- a/include/uapi/linux/tee.h
>> +++ b/include/uapi/linux/tee.h
>> @@ -56,6 +56,7 @@
>>   */
>>  #define TEE_IMPL_ID_OPTEE      1
>>  #define TEE_IMPL_ID_AMDTEE     2
>> +#define TEE_IMPL_ID_TSTEE      3
>>
>>  /*
>>   * OP-TEE specific capabilities
>> --
>> 2.34.1
>>