diff mbox series

[v6,3/4] tee: optee: add TEE bus device enumeration support

Message ID 1548740978-28495-4-git-send-email-sumit.garg@linaro.org
State Accepted
Commit c3fa24af92445c419c19df5981ab4e41a3ae3361
Headers show
Series None | expand

Commit Message

Sumit Garg Jan. 29, 2019, 5:49 a.m. UTC 
OP-TEE provides a pseudo TA to enumerate TAs which can act as devices/
services for TEE bus. So implement device enumeration using invoke
function: PTA_CMD_GET_DEVICES provided by pseudo TA to fetch array of
device UUIDs. Also register these enumerated devices with TEE bus as
"optee-clntX" device.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>

Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

---
 drivers/tee/optee/Makefile        |   1 +
 drivers/tee/optee/core.c          |   4 +
 drivers/tee/optee/device.c        | 155 ++++++++++++++++++++++++++++++++++++++
 drivers/tee/optee/optee_private.h |   3 +
 4 files changed, 163 insertions(+)
 create mode 100644 drivers/tee/optee/device.c

-- 
2.7.4

Comments

Jens Wiklander Feb. 1, 2019, 8:28 a.m. UTC | #1 
On Tue, Jan 29, 2019 at 11:19:37AM +0530, Sumit Garg wrote:
> OP-TEE provides a pseudo TA to enumerate TAs which can act as devices/

> services for TEE bus. So implement device enumeration using invoke

> function: PTA_CMD_GET_DEVICES provided by pseudo TA to fetch array of

> device UUIDs. Also register these enumerated devices with TEE bus as

> "optee-clntX" device.

> 

> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>

> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

> ---

>  drivers/tee/optee/Makefile        |   1 +

>  drivers/tee/optee/core.c          |   4 +

>  drivers/tee/optee/device.c        | 155 ++++++++++++++++++++++++++++++++++++++

>  drivers/tee/optee/optee_private.h |   3 +

>  4 files changed, 163 insertions(+)

>  create mode 100644 drivers/tee/optee/device.c

> 

> diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile

> index 48d262a..56263ae 100644

> --- a/drivers/tee/optee/Makefile

> +++ b/drivers/tee/optee/Makefile

> @@ -5,3 +5,4 @@ optee-objs += call.o

>  optee-objs += rpc.o

>  optee-objs += supp.o

>  optee-objs += shm_pool.o

> +optee-objs += device.o

> diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c

> index e5efce3..ac59c77 100644

> --- a/drivers/tee/optee/core.c

> +++ b/drivers/tee/optee/core.c

> @@ -634,6 +634,10 @@ static struct optee *optee_probe(struct device_node *np)

>  	if (optee->sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)

>  		pr_info("dynamic shared memory is enabled\n");

>  

> +	rc = optee_enumerate_devices();

> +	if (rc)

> +		goto err;

> +

>  	pr_info("initialized driver\n");

>  	return optee;

>  err:

> diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c

> new file mode 100644

> index 0000000..c24c37f

> --- /dev/null

> +++ b/drivers/tee/optee/device.c

> @@ -0,0 +1,155 @@

> +// SPDX-License-Identifier: GPL-2.0

> +/*

> + * Copyright (C) 2019 Linaro Ltd.

> + */

> +

> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

> +

> +#include <linux/kernel.h>

> +#include <linux/slab.h>

> +#include <linux/tee_drv.h>

> +#include <linux/uuid.h>

> +#include "optee_private.h"

> +

> +/*

> + * Get device UUIDs

> + *

> + * [out]     memref[0]        Array of device UUIDs

> + *

> + * Return codes:

> + * TEE_SUCCESS - Invoke command success

> + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param

> + * TEE_ERROR_SHORT_BUFFER - Output buffer size less than required

> + */

> +#define PTA_CMD_GET_DEVICES		0x0

> +

> +static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)

> +{

> +	if (ver->impl_id == TEE_IMPL_ID_OPTEE)

> +		return 1;

> +	else

> +		return 0;

> +}

> +

> +static int get_devices(struct tee_context *ctx, u32 session,

> +		       struct tee_shm *device_shm, u32 *shm_size)

> +{

> +	u32 ret = 0;

> +	struct tee_ioctl_invoke_arg inv_arg = {0};

> +	struct tee_param param[4] = {0};

> +

> +	/* Invoke PTA_CMD_GET_DEVICES function */

> +	inv_arg.func = PTA_CMD_GET_DEVICES;

> +	inv_arg.session = session;

> +	inv_arg.num_params = 4;

> +

> +	/* Fill invoke cmd params */

> +	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;

> +	param[0].u.memref.shm = device_shm;

> +	param[0].u.memref.size = *shm_size;

> +	param[0].u.memref.shm_offs = 0;

> +

> +	ret = tee_client_invoke_func(ctx, &inv_arg, param);

> +	if ((ret < 0) || ((inv_arg.ret != TEEC_SUCCESS) &&

> +			  (inv_arg.ret != TEEC_ERROR_SHORT_BUFFER))) {

> +		pr_err("PTA_CMD_GET_DEVICES invoke function err: %x\n",

> +		       inv_arg.ret);

> +		return -EINVAL;

> +	}

> +

> +	*shm_size = param[0].u.memref.size;

> +

> +	return 0;

> +}

> +

> +static int optee_register_device(const uuid_t *device_uuid, u32 device_id)

> +{

> +	struct tee_client_device *optee_device = NULL;

> +	int rc;

> +

> +	optee_device = kzalloc(sizeof(*optee_device), GFP_KERNEL);

> +	if (!optee_device)

> +		return -ENOMEM;

> +

> +	optee_device->dev.bus = &tee_bus_type;

> +	dev_set_name(&optee_device->dev, "optee-clnt%u", device_id);

> +	uuid_copy(&optee_device->id.uuid, device_uuid);

> +

> +	rc = device_register(&optee_device->dev);

> +	if (rc) {

> +		pr_err("device registration failed, err: %d\n", rc);

> +		kfree(optee_device);

> +	}

> +

> +	return rc;

> +}

> +

> +int optee_enumerate_devices(void)

> +{

> +	const uuid_t pta_uuid =

> +		UUID_INIT(0x7011a688, 0xddde, 0x4053,

> +			  0xa5, 0xa9, 0x7b, 0x3c, 0x4d, 0xdf, 0x13, 0xb8);

> +	struct tee_ioctl_open_session_arg sess_arg = {0};

> +	struct tee_shm *device_shm = NULL;

> +	const uuid_t *device_uuid = NULL;

> +	struct tee_context *ctx = NULL;

> +	u32 shm_size = 0, idx, num_devices = 0;

> +	int rc;

> +

> +	/* Open context with OP-TEE driver */

> +	ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);

> +	if (IS_ERR(ctx))

> +		return -ENODEV;

> +

> +	/* Open session with device enumeration pseudo TA */

> +	memcpy(sess_arg.uuid, pta_uuid.b, TEE_IOCTL_UUID_LEN);

> +	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;

> +	sess_arg.num_params = 0;

> +

> +	rc = tee_client_open_session(ctx, &sess_arg, NULL);

> +	if ((rc < 0) || (sess_arg.ret != TEEC_SUCCESS)) {

> +		/* Device enumeration pseudo TA not found */

> +		rc = 0;

> +		goto out_ctx;

> +	}

> +

> +	rc = get_devices(ctx, sess_arg.session, NULL, &shm_size);

> +	if (rc < 0)


While testing I discovered that this line should be:
        if (rc < 0 || !shm_size)

to cover the common case where there's no devices. I'll fixup the commit
with this trivial change.

Cheers,
Jens

> +		goto out_sess;

> +

> +	device_shm = tee_shm_alloc(ctx, shm_size,

> +				   TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);

> +	if (IS_ERR(device_shm)) {

> +		pr_err("tee_shm_alloc failed\n");

> +		rc = PTR_ERR(device_shm);

> +		goto out_sess;

> +	}

> +

> +	rc = get_devices(ctx, sess_arg.session, device_shm, &shm_size);

> +	if (rc < 0)

> +		goto out_shm;

> +

> +	device_uuid = tee_shm_get_va(device_shm, 0);

> +	if (IS_ERR(device_uuid)) {

> +		pr_err("tee_shm_get_va failed\n");

> +		rc = PTR_ERR(device_uuid);

> +		goto out_shm;

> +	}

> +

> +	num_devices = shm_size / sizeof(uuid_t);

> +

> +	for (idx = 0; idx < num_devices; idx++) {

> +		rc = optee_register_device(&device_uuid[idx], idx);

> +		if (rc)

> +			goto out_shm;

> +	}

> +

> +out_shm:

> +	tee_shm_free(device_shm);

> +out_sess:

> +	tee_client_close_session(ctx, sess_arg.session);

> +out_ctx:

> +	tee_client_close_context(ctx);

> +

> +	return rc;

> +}

> diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h

> index 35e7938..a5e84af 100644

> --- a/drivers/tee/optee/optee_private.h

> +++ b/drivers/tee/optee/optee_private.h

> @@ -28,6 +28,7 @@

>  #define TEEC_ERROR_BAD_PARAMETERS	0xFFFF0006

>  #define TEEC_ERROR_COMMUNICATION	0xFFFF000E

>  #define TEEC_ERROR_OUT_OF_MEMORY	0xFFFF000C

> +#define TEEC_ERROR_SHORT_BUFFER		0xFFFF0010

>  

>  #define TEEC_ORIGIN_COMMS		0x00000002

>  

> @@ -181,6 +182,8 @@ void optee_free_pages_list(void *array, size_t num_entries);

>  void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,

>  			   size_t page_offset);

>  

> +int optee_enumerate_devices(void);

> +

>  /*

>   * Small helpers

>   */

> -- 

> 2.7.4

>
Sumit Garg Feb. 1, 2019, 8:42 a.m. UTC | #2 
On Fri, 1 Feb 2019 at 13:58, Jens Wiklander <jens.wiklander@linaro.org> wrote:
>

> On Tue, Jan 29, 2019 at 11:19:37AM +0530, Sumit Garg wrote:

> > OP-TEE provides a pseudo TA to enumerate TAs which can act as devices/

> > services for TEE bus. So implement device enumeration using invoke

> > function: PTA_CMD_GET_DEVICES provided by pseudo TA to fetch array of

> > device UUIDs. Also register these enumerated devices with TEE bus as

> > "optee-clntX" device.

> >

> > Signed-off-by: Sumit Garg <sumit.garg@linaro.org>

> > Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

> > ---

> >  drivers/tee/optee/Makefile        |   1 +

> >  drivers/tee/optee/core.c          |   4 +

> >  drivers/tee/optee/device.c        | 155 ++++++++++++++++++++++++++++++++++++++

> >  drivers/tee/optee/optee_private.h |   3 +

> >  4 files changed, 163 insertions(+)

> >  create mode 100644 drivers/tee/optee/device.c

> >

> > diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile

> > index 48d262a..56263ae 100644

> > --- a/drivers/tee/optee/Makefile

> > +++ b/drivers/tee/optee/Makefile

> > @@ -5,3 +5,4 @@ optee-objs += call.o

> >  optee-objs += rpc.o

> >  optee-objs += supp.o

> >  optee-objs += shm_pool.o

> > +optee-objs += device.o

> > diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c

> > index e5efce3..ac59c77 100644

> > --- a/drivers/tee/optee/core.c

> > +++ b/drivers/tee/optee/core.c

> > @@ -634,6 +634,10 @@ static struct optee *optee_probe(struct device_node *np)

> >       if (optee->sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)

> >               pr_info("dynamic shared memory is enabled\n");

> >

> > +     rc = optee_enumerate_devices();

> > +     if (rc)

> > +             goto err;

> > +

> >       pr_info("initialized driver\n");

> >       return optee;

> >  err:

> > diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c

> > new file mode 100644

> > index 0000000..c24c37f

> > --- /dev/null

> > +++ b/drivers/tee/optee/device.c

> > @@ -0,0 +1,155 @@

> > +// SPDX-License-Identifier: GPL-2.0

> > +/*

> > + * Copyright (C) 2019 Linaro Ltd.

> > + */

> > +

> > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

> > +

> > +#include <linux/kernel.h>

> > +#include <linux/slab.h>

> > +#include <linux/tee_drv.h>

> > +#include <linux/uuid.h>

> > +#include "optee_private.h"

> > +

> > +/*

> > + * Get device UUIDs

> > + *

> > + * [out]     memref[0]        Array of device UUIDs

> > + *

> > + * Return codes:

> > + * TEE_SUCCESS - Invoke command success

> > + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param

> > + * TEE_ERROR_SHORT_BUFFER - Output buffer size less than required

> > + */

> > +#define PTA_CMD_GET_DEVICES          0x0

> > +

> > +static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)

> > +{

> > +     if (ver->impl_id == TEE_IMPL_ID_OPTEE)

> > +             return 1;

> > +     else

> > +             return 0;

> > +}

> > +

> > +static int get_devices(struct tee_context *ctx, u32 session,

> > +                    struct tee_shm *device_shm, u32 *shm_size)

> > +{

> > +     u32 ret = 0;

> > +     struct tee_ioctl_invoke_arg inv_arg = {0};

> > +     struct tee_param param[4] = {0};

> > +

> > +     /* Invoke PTA_CMD_GET_DEVICES function */

> > +     inv_arg.func = PTA_CMD_GET_DEVICES;

> > +     inv_arg.session = session;

> > +     inv_arg.num_params = 4;

> > +

> > +     /* Fill invoke cmd params */

> > +     param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;

> > +     param[0].u.memref.shm = device_shm;

> > +     param[0].u.memref.size = *shm_size;

> > +     param[0].u.memref.shm_offs = 0;

> > +

> > +     ret = tee_client_invoke_func(ctx, &inv_arg, param);

> > +     if ((ret < 0) || ((inv_arg.ret != TEEC_SUCCESS) &&

> > +                       (inv_arg.ret != TEEC_ERROR_SHORT_BUFFER))) {

> > +             pr_err("PTA_CMD_GET_DEVICES invoke function err: %x\n",

> > +                    inv_arg.ret);

> > +             return -EINVAL;

> > +     }

> > +

> > +     *shm_size = param[0].u.memref.size;

> > +

> > +     return 0;

> > +}

> > +

> > +static int optee_register_device(const uuid_t *device_uuid, u32 device_id)

> > +{

> > +     struct tee_client_device *optee_device = NULL;

> > +     int rc;

> > +

> > +     optee_device = kzalloc(sizeof(*optee_device), GFP_KERNEL);

> > +     if (!optee_device)

> > +             return -ENOMEM;

> > +

> > +     optee_device->dev.bus = &tee_bus_type;

> > +     dev_set_name(&optee_device->dev, "optee-clnt%u", device_id);

> > +     uuid_copy(&optee_device->id.uuid, device_uuid);

> > +

> > +     rc = device_register(&optee_device->dev);

> > +     if (rc) {

> > +             pr_err("device registration failed, err: %d\n", rc);

> > +             kfree(optee_device);

> > +     }

> > +

> > +     return rc;

> > +}

> > +

> > +int optee_enumerate_devices(void)

> > +{

> > +     const uuid_t pta_uuid =

> > +             UUID_INIT(0x7011a688, 0xddde, 0x4053,

> > +                       0xa5, 0xa9, 0x7b, 0x3c, 0x4d, 0xdf, 0x13, 0xb8);

> > +     struct tee_ioctl_open_session_arg sess_arg = {0};

> > +     struct tee_shm *device_shm = NULL;

> > +     const uuid_t *device_uuid = NULL;

> > +     struct tee_context *ctx = NULL;

> > +     u32 shm_size = 0, idx, num_devices = 0;

> > +     int rc;

> > +

> > +     /* Open context with OP-TEE driver */

> > +     ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);

> > +     if (IS_ERR(ctx))

> > +             return -ENODEV;

> > +

> > +     /* Open session with device enumeration pseudo TA */

> > +     memcpy(sess_arg.uuid, pta_uuid.b, TEE_IOCTL_UUID_LEN);

> > +     sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;

> > +     sess_arg.num_params = 0;

> > +

> > +     rc = tee_client_open_session(ctx, &sess_arg, NULL);

> > +     if ((rc < 0) || (sess_arg.ret != TEEC_SUCCESS)) {

> > +             /* Device enumeration pseudo TA not found */

> > +             rc = 0;

> > +             goto out_ctx;

> > +     }

> > +

> > +     rc = get_devices(ctx, sess_arg.session, NULL, &shm_size);

> > +     if (rc < 0)

>

> While testing I discovered that this line should be:

>         if (rc < 0 || !shm_size)

>


Ah, yes you are correct. BTW, thanks for testing.

> to cover the common case where there's no devices. I'll fixup the commit

> with this trivial change.

>


Thanks,
-Sumit

> Cheers,

> Jens

>

> > +             goto out_sess;

> > +

> > +     device_shm = tee_shm_alloc(ctx, shm_size,

> > +                                TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);

> > +     if (IS_ERR(device_shm)) {

> > +             pr_err("tee_shm_alloc failed\n");

> > +             rc = PTR_ERR(device_shm);

> > +             goto out_sess;

> > +     }

> > +

> > +     rc = get_devices(ctx, sess_arg.session, device_shm, &shm_size);

> > +     if (rc < 0)

> > +             goto out_shm;

> > +

> > +     device_uuid = tee_shm_get_va(device_shm, 0);

> > +     if (IS_ERR(device_uuid)) {

> > +             pr_err("tee_shm_get_va failed\n");

> > +             rc = PTR_ERR(device_uuid);

> > +             goto out_shm;

> > +     }

> > +

> > +     num_devices = shm_size / sizeof(uuid_t);

> > +

> > +     for (idx = 0; idx < num_devices; idx++) {

> > +             rc = optee_register_device(&device_uuid[idx], idx);

> > +             if (rc)

> > +                     goto out_shm;

> > +     }

> > +

> > +out_shm:

> > +     tee_shm_free(device_shm);

> > +out_sess:

> > +     tee_client_close_session(ctx, sess_arg.session);

> > +out_ctx:

> > +     tee_client_close_context(ctx);

> > +

> > +     return rc;

> > +}

> > diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h

> > index 35e7938..a5e84af 100644

> > --- a/drivers/tee/optee/optee_private.h

> > +++ b/drivers/tee/optee/optee_private.h

> > @@ -28,6 +28,7 @@

> >  #define TEEC_ERROR_BAD_PARAMETERS    0xFFFF0006

> >  #define TEEC_ERROR_COMMUNICATION     0xFFFF000E

> >  #define TEEC_ERROR_OUT_OF_MEMORY     0xFFFF000C

> > +#define TEEC_ERROR_SHORT_BUFFER              0xFFFF0010

> >

> >  #define TEEC_ORIGIN_COMMS            0x00000002

> >

> > @@ -181,6 +182,8 @@ void optee_free_pages_list(void *array, size_t num_entries);

> >  void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,

> >                          size_t page_offset);

> >

> > +int optee_enumerate_devices(void);

> > +

> >  /*

> >   * Small helpers

> >   */

> > --

> > 2.7.4

> >
diff mbox series

Patch

diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile
index 48d262a..56263ae 100644
--- a/drivers/tee/optee/Makefile
+++ b/drivers/tee/optee/Makefile
@@ -5,3 +5,4 @@  optee-objs += call.o
 optee-objs += rpc.o
 optee-objs += supp.o
 optee-objs += shm_pool.o
+optee-objs += device.o
diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index e5efce3..ac59c77 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -634,6 +634,10 @@  static struct optee *optee_probe(struct device_node *np)
 	if (optee->sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)
 		pr_info("dynamic shared memory is enabled\n");
 
+	rc = optee_enumerate_devices();
+	if (rc)
+		goto err;
+
 	pr_info("initialized driver\n");
 	return optee;
 err:
diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c
new file mode 100644
index 0000000..c24c37f
--- /dev/null
+++ b/drivers/tee/optee/device.c
@@ -0,0 +1,155 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Linaro Ltd.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/tee_drv.h>
+#include <linux/uuid.h>
+#include "optee_private.h"
+
+/*
+ * Get device UUIDs
+ *
+ * [out]     memref[0]        Array of device UUIDs
+ *
+ * Return codes:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ * TEE_ERROR_SHORT_BUFFER - Output buffer size less than required
+ */
+#define PTA_CMD_GET_DEVICES		0x0
+
+static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
+{
+	if (ver->impl_id == TEE_IMPL_ID_OPTEE)
+		return 1;
+	else
+		return 0;
+}
+
+static int get_devices(struct tee_context *ctx, u32 session,
+		       struct tee_shm *device_shm, u32 *shm_size)
+{
+	u32 ret = 0;
+	struct tee_ioctl_invoke_arg inv_arg = {0};
+	struct tee_param param[4] = {0};
+
+	/* Invoke PTA_CMD_GET_DEVICES function */
+	inv_arg.func = PTA_CMD_GET_DEVICES;
+	inv_arg.session = session;
+	inv_arg.num_params = 4;
+
+	/* Fill invoke cmd params */
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
+	param[0].u.memref.shm = device_shm;
+	param[0].u.memref.size = *shm_size;
+	param[0].u.memref.shm_offs = 0;
+
+	ret = tee_client_invoke_func(ctx, &inv_arg, param);
+	if ((ret < 0) || ((inv_arg.ret != TEEC_SUCCESS) &&
+			  (inv_arg.ret != TEEC_ERROR_SHORT_BUFFER))) {
+		pr_err("PTA_CMD_GET_DEVICES invoke function err: %x\n",
+		       inv_arg.ret);
+		return -EINVAL;
+	}
+
+	*shm_size = param[0].u.memref.size;
+
+	return 0;
+}
+
+static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
+{
+	struct tee_client_device *optee_device = NULL;
+	int rc;
+
+	optee_device = kzalloc(sizeof(*optee_device), GFP_KERNEL);
+	if (!optee_device)
+		return -ENOMEM;
+
+	optee_device->dev.bus = &tee_bus_type;
+	dev_set_name(&optee_device->dev, "optee-clnt%u", device_id);
+	uuid_copy(&optee_device->id.uuid, device_uuid);
+
+	rc = device_register(&optee_device->dev);
+	if (rc) {
+		pr_err("device registration failed, err: %d\n", rc);
+		kfree(optee_device);
+	}
+
+	return rc;
+}
+
+int optee_enumerate_devices(void)
+{
+	const uuid_t pta_uuid =
+		UUID_INIT(0x7011a688, 0xddde, 0x4053,
+			  0xa5, 0xa9, 0x7b, 0x3c, 0x4d, 0xdf, 0x13, 0xb8);
+	struct tee_ioctl_open_session_arg sess_arg = {0};
+	struct tee_shm *device_shm = NULL;
+	const uuid_t *device_uuid = NULL;
+	struct tee_context *ctx = NULL;
+	u32 shm_size = 0, idx, num_devices = 0;
+	int rc;
+
+	/* Open context with OP-TEE driver */
+	ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);
+	if (IS_ERR(ctx))
+		return -ENODEV;
+
+	/* Open session with device enumeration pseudo TA */
+	memcpy(sess_arg.uuid, pta_uuid.b, TEE_IOCTL_UUID_LEN);
+	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
+	sess_arg.num_params = 0;
+
+	rc = tee_client_open_session(ctx, &sess_arg, NULL);
+	if ((rc < 0) || (sess_arg.ret != TEEC_SUCCESS)) {
+		/* Device enumeration pseudo TA not found */
+		rc = 0;
+		goto out_ctx;
+	}
+
+	rc = get_devices(ctx, sess_arg.session, NULL, &shm_size);
+	if (rc < 0)
+		goto out_sess;
+
+	device_shm = tee_shm_alloc(ctx, shm_size,
+				   TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
+	if (IS_ERR(device_shm)) {
+		pr_err("tee_shm_alloc failed\n");
+		rc = PTR_ERR(device_shm);
+		goto out_sess;
+	}
+
+	rc = get_devices(ctx, sess_arg.session, device_shm, &shm_size);
+	if (rc < 0)
+		goto out_shm;
+
+	device_uuid = tee_shm_get_va(device_shm, 0);
+	if (IS_ERR(device_uuid)) {
+		pr_err("tee_shm_get_va failed\n");
+		rc = PTR_ERR(device_uuid);
+		goto out_shm;
+	}
+
+	num_devices = shm_size / sizeof(uuid_t);
+
+	for (idx = 0; idx < num_devices; idx++) {
+		rc = optee_register_device(&device_uuid[idx], idx);
+		if (rc)
+			goto out_shm;
+	}
+
+out_shm:
+	tee_shm_free(device_shm);
+out_sess:
+	tee_client_close_session(ctx, sess_arg.session);
+out_ctx:
+	tee_client_close_context(ctx);
+
+	return rc;
+}
diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
index 35e7938..a5e84af 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -28,6 +28,7 @@ 
 #define TEEC_ERROR_BAD_PARAMETERS	0xFFFF0006
 #define TEEC_ERROR_COMMUNICATION	0xFFFF000E
 #define TEEC_ERROR_OUT_OF_MEMORY	0xFFFF000C
+#define TEEC_ERROR_SHORT_BUFFER		0xFFFF0010
 
 #define TEEC_ORIGIN_COMMS		0x00000002
 
@@ -181,6 +182,8 @@  void optee_free_pages_list(void *array, size_t num_entries);
 void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,
 			   size_t page_offset);
 
+int optee_enumerate_devices(void);
+
 /*
  * Small helpers
  */