[PATCH v3 0/4] Introduce TEE bus driver framework

[PATCH v3 0/4] Introduce TEE bus driver framework

[Sumit Garg]

This series introduces a generic TEE bus driver concept for TEE based
kernel drivers which would like to communicate with TEE based devices/
services.

Patch #1 adds TEE bus concept where devices/services are identified via
Universally Unique Identifier (UUID) and drivers register a table of
device UUIDs which they can support. This concept also allows for device
enumeration to be specific to corresponding TEE implementation like
OP-TEE etc.

Patch #2 adds supp_nowait flag for non-blocking requests arising via
TEE internal client interface.

Patch #3 adds TEE bus device enumeration support for OP-TEE. OP-TEE
provides a pseudo TA to enumerate TAs which can act as devices/services
for TEE bus.

Patch #4 adds OP-TEE based hwrng driver which act as TEE bus driver.
On ARM SoC's with TrustZone enabled, peripherals like entropy sources
might not be accessible to normal world (linux in this case) and rather
accessible to secure world (OP-TEE in this case) only. So this driver
aims to provides a generic interface to OP-TEE based random number
generator service.

Example case is Developerbox based on Socionext's Synquacer SoC [1]
which provides 7 thermal sensors accessible from secure world only which
could be used as entropy sources (thermal/measurement noise).

[1] https://www.96boards.org/product/developerbox/

Changes in v3:

1. Fixed bus error path in Patch #1.
2. Reversed order of Patch #2 and #3.
3. Fixed miscellaneous syntax comments and memory leak.
4. Added comments in Patch #2 for supp_nowait flag.

Changes in v2:

Based on review comments, the scope of this series has increased as
follows:

1. Added TEE bus driver framework.
2. Added OP-TEE based device enumeration.
3. Register optee-rng driver as TEE bus driver.
4. Removed DT dependency for optee-rng device UUID.
5. Added supp_nowait flag.

Sumit Garg (4):
  tee: add bus driver framework for TEE based devices
  tee: add supp_nowait flag in tee_context struct
  tee: optee: add TEE bus device enumeration support
  hwrng: add OP-TEE based rng driver

 MAINTAINERS                        |   5 +
 drivers/char/hw_random/Kconfig     |  15 ++
 drivers/char/hw_random/Makefile    |   1 +
 drivers/char/hw_random/optee-rng.c | 272 +++++++++++++++++++++++++++++++++++++
 drivers/tee/optee/Makefile         |   1 +
 drivers/tee/optee/core.c           |   4 +
 drivers/tee/optee/device.c         | 153 +++++++++++++++++++++
 drivers/tee/optee/optee_private.h  |   3 +
 drivers/tee/optee/supp.c           |  10 +-
 drivers/tee/tee_core.c             |  56 +++++++-
 include/linux/tee_drv.h            |  42 ++++++
 11 files changed, 558 insertions(+), 4 deletions(-)
 create mode 100644 drivers/char/hw_random/optee-rng.c
 create mode 100644 drivers/tee/optee/device.c

-- 
2.7.4


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[PATCH v3 1/4] tee: add bus driver framework for TEE based devices

[Sumit Garg]

Introduce a generic TEE bus driver concept for TEE based kernel drivers
which would like to communicate with TEE based devices/services.

In this TEE bus concept, devices/services are identified via Universally
Unique Identifier (UUID) and drivers register a table of device UUIDs
which they can support.

So this TEE bus framework registers a match() callback function which
iterates over the driver UUID table to find a corresponding match for
device UUID. If a match is found, then this particular device is probed
via corresponding probe api registered by the driver. This process
happens whenever a device or a driver is registered with TEE bus.

Also this framework allows for device enumeration to be specific to
corresponding TEE implementation like OP-TEE etc.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
 drivers/tee/tee_core.c  | 43 ++++++++++++++++++++++++++++++++++++++++---
 include/linux/tee_drv.h | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 7b2bb4c..a685940 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -15,7 +15,6 @@
 #define pr_fmt(fmt) "%s: " fmt, __func__
 
 #include <linux/cdev.h>
-#include <linux/device.h>
 #include <linux/fs.h>
 #include <linux/idr.h>
 #include <linux/module.h>
@@ -1027,6 +1026,30 @@ int tee_client_invoke_func(struct tee_context *ctx,
 }
 EXPORT_SYMBOL_GPL(tee_client_invoke_func);
 
+static int tee_client_device_match(struct device *dev,
+				   struct device_driver *drv)
+{
+	struct tee_client_device *tee_device;
+	const struct tee_client_device_id *id_table;
+
+	tee_device = to_tee_client_device(dev);
+	id_table = to_tee_client_driver(drv)->id_table;
+
+	while (!uuid_is_null(&id_table->uuid)) {
+		if (uuid_equal(&tee_device->id.uuid, &id_table->uuid))
+			return 1;
+		id_table++;
+	}
+
+	return 0;
+}
+
+struct bus_type tee_bus_type = {
+	.name		= "tee",
+	.match		= tee_client_device_match,
+};
+EXPORT_SYMBOL_GPL(tee_bus_type);
+
 static int __init tee_init(void)
 {
 	int rc;
@@ -1040,10 +1063,23 @@ static int __init tee_init(void)
 	rc = alloc_chrdev_region(&tee_devt, 0, TEE_NUM_DEVICES, "tee");
 	if (rc) {
 		pr_err("failed to allocate char dev region\n");
-		class_destroy(tee_class);
-		tee_class = NULL;
+		goto chrdev_err;
 	}
 
+	rc = bus_register(&tee_bus_type);
+	if (rc) {
+		pr_err("failed to register tee bus\n");
+		goto bus_err;
+	}
+
+	return 0;
+
+bus_err:
+	unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
+chrdev_err:
+	class_destroy(tee_class);
+	tee_class = NULL;
+
 	return rc;
 }
 
@@ -1052,6 +1088,7 @@ static void __exit tee_exit(void)
 	class_destroy(tee_class);
 	tee_class = NULL;
 	unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
+	bus_unregister(&tee_bus_type);
 }
 
 subsys_initcall(tee_init);
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 6cfe058..ed16bf1 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -20,6 +20,8 @@
 #include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/tee.h>
+#include <linux/device.h>
+#include <linux/uuid.h>
 
 /*
  * The file describes the API provided by the generic TEE driver to the
@@ -538,4 +540,38 @@ static inline bool tee_param_is_memref(struct tee_param *param)
 	}
 }
 
+extern struct bus_type tee_bus_type;
+
+/**
+ * struct tee_client_device_id - tee based device identifier
+ * @uuid:		For TEE based client devices we use the device uuid
+ *			as the identifier.
+ */
+struct tee_client_device_id {
+	uuid_t uuid;
+};
+
+/**
+ * struct tee_client_device - tee based device
+ * @id:			device identifier
+ * @dev:		device structure
+ */
+struct tee_client_device {
+	struct tee_client_device_id id;
+	struct device dev;
+};
+#define to_tee_client_device(d) container_of(d, struct tee_client_device, dev)
+
+/**
+ * struct tee_client_driver - tee client driver
+ * @id_table:		device id table supported by this driver
+ * @driver:		driver structure
+ */
+struct tee_client_driver {
+	const struct tee_client_device_id *id_table;
+	struct device_driver driver;
+};
+#define to_tee_client_driver(d) \
+		container_of(d, struct tee_client_driver, driver)
+
 #endif /*__TEE_DRV_H*/
-- 
2.7.4


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[PATCH v3 2/4] tee: add supp_nowait flag in tee_context struct

[Sumit Garg]

This flag indicates that requests in this context should not wait for
tee-supplicant daemon to be started if not present and just return
with an error code. It is needed for requests which should be
non-blocking in nature like ones arising from TEE based kernel drivers
or any in kernel api that uses TEE internal client interface.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
 drivers/tee/optee/supp.c | 10 +++++++++-
 drivers/tee/tee_core.c   | 13 +++++++++++++
 include/linux/tee_drv.h  |  6 ++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c
index 43626e1..92f56b8 100644
--- a/drivers/tee/optee/supp.c
+++ b/drivers/tee/optee/supp.c
@@ -88,10 +88,18 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params,
 {
 	struct optee *optee = tee_get_drvdata(ctx->teedev);
 	struct optee_supp *supp = &optee->supp;
-	struct optee_supp_req *req = kzalloc(sizeof(*req), GFP_KERNEL);
+	struct optee_supp_req *req;
 	bool interruptable;
 	u32 ret;
 
+	/*
+	 * Return in case there is no supplicant available and
+	 * non-blocking request.
+	 */
+	if (!supp->ctx && ctx->supp_nowait)
+		return TEEC_ERROR_COMMUNICATION;
+
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
 	if (!req)
 		return TEEC_ERROR_OUT_OF_MEMORY;
 
diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index a685940..eed83bd 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -105,6 +105,11 @@ static int tee_open(struct inode *inode, struct file *filp)
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
+	/*
+	 * Default user-space behaviour is to wait for tee-supplicant
+	 * if not present for any requests in this context.
+	 */
+	ctx->supp_nowait = false;
 	filp->private_data = ctx;
 	return 0;
 }
@@ -981,6 +986,14 @@ tee_client_open_context(struct tee_context *start,
 	} while (IS_ERR(ctx) && PTR_ERR(ctx) != -ENOMEM);
 
 	put_device(put_dev);
+	/*
+	 * Default behaviour for in kernel client is to not wait for
+	 * tee-supplicant if not present for any requests in this context.
+	 * Also this flag could be configured again before call to
+	 * tee_client_open_session() if any in kernel client requires
+	 * different behaviour.
+	 */
+	ctx->supp_nowait = true;
 	return ctx;
 }
 EXPORT_SYMBOL_GPL(tee_client_open_context);
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index ed16bf1..fe1a920 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -49,6 +49,11 @@ struct tee_shm_pool;
  * @releasing:  flag that indicates if context is being released right now.
  *		It is needed to break circular dependency on context during
  *              shared memory release.
+ * @supp_nowait: flag that indicates that requests in this context should not
+ *              wait for tee-supplicant daemon to be started if not present
+ *              and just return with an error code. It is needed for requests
+ *              that arises from TEE based kernel drivers that should be
+ *              non-blocking in nature.
  */
 struct tee_context {
 	struct tee_device *teedev;
@@ -56,6 +61,7 @@ struct tee_context {
 	void *data;
 	struct kref refcount;
 	bool releasing;
+	bool supp_nowait;
 };
 
 struct tee_param_memref {
-- 
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[PATCH v3 3/4] tee: optee: add TEE bus device enumeration support

[Sumit Garg]

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>
---
 drivers/tee/optee/Makefile        |   1 +
 drivers/tee/optee/core.c          |   4 +
 drivers/tee/optee/device.c        | 153 ++++++++++++++++++++++++++++++++++++++
 drivers/tee/optee/optee_private.h |   3 +
 4 files changed, 161 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..987e552
--- /dev/null
+++ b/drivers/tee/optee/device.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Linaro Ltd.
+ */
+
+#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
  */
-- 
2.7.4


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[PATCH v3 4/4] hwrng: add OP-TEE based rng driver

[Sumit Garg]

On ARM SoC's with TrustZone enabled, peripherals like entropy sources
might not be accessible to normal world (linux in this case) and rather
accessible to secure world (OP-TEE in this case) only. So this driver
aims to provides a generic interface to OP-TEE based random number
generator service.

This driver registers on TEE bus to interact with OP-TEE based rng
device/service.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
 MAINTAINERS                        |   5 +
 drivers/char/hw_random/Kconfig     |  15 ++
 drivers/char/hw_random/Makefile    |   1 +
 drivers/char/hw_random/optee-rng.c | 272 +++++++++++++++++++++++++++++++++++++
 4 files changed, 293 insertions(+)
 create mode 100644 drivers/char/hw_random/optee-rng.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 32d44447..502733c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11260,6 +11260,11 @@ M:	Jens Wiklander <jens.wiklander@linaro.org>
 S:	Maintained
 F:	drivers/tee/optee/
 
+OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER
+M:	Sumit Garg <sumit.garg@linaro.org>
+S:	Maintained
+F:	drivers/char/hw_random/optee-rng.c
+
 OPA-VNIC DRIVER
 M:	Dennis Dalessandro <dennis.dalessandro@intel.com>
 M:	Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index dac895d..25a7d8f 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -424,6 +424,21 @@ config HW_RANDOM_EXYNOS
 	  will be called exynos-trng.
 
 	  If unsure, say Y.
+
+config HW_RANDOM_OPTEE
+	tristate "OP-TEE based Random Number Generator support"
+	depends on OPTEE
+	default HW_RANDOM
+	help
+	  This  driver provides support for OP-TEE based Random Number
+	  Generator on ARM SoCs where hardware entropy sources are not
+	  accessible to normal world (Linux).
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called optee-rng.
+
+	  If unsure, say Y.
+
 endif # HW_RANDOM
 
 config UML_RANDOM
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index e35ec3c..7c9ef4a 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -38,3 +38,4 @@ obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o
 obj-$(CONFIG_HW_RANDOM_MTK)	+= mtk-rng.o
 obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o
 obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o
+obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o
diff --git a/drivers/char/hw_random/optee-rng.c b/drivers/char/hw_random/optee-rng.c
new file mode 100644
index 0000000..24f7435
--- /dev/null
+++ b/drivers/char/hw_random/optee-rng.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018-2019 Linaro Ltd.
+ */
+
+#include <linux/delay.h>
+#include <linux/of.h>
+#include <linux/hw_random.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/tee_drv.h>
+#include <linux/uuid.h>
+
+#define DRIVER_NAME "optee-rng"
+
+#define TEE_ERROR_HEALTH_TEST_FAIL	0x00000001
+
+/*
+ * TA_CMD_GET_ENTROPY - Get Entropy from RNG
+ *
+ * param[0] (inout memref) - Entropy buffer memory reference
+ * param[1] unused
+ * param[2] unused
+ * param[3] unused
+ *
+ * Result:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ * TEE_ERROR_NOT_SUPPORTED - Requested entropy size greater than size of pool
+ * TEE_ERROR_HEALTH_TEST_FAIL - Continuous health testing failed
+ */
+#define TA_CMD_GET_ENTROPY		0x0
+
+/*
+ * TA_CMD_GET_RNG_INFO - Get RNG information
+ *
+ * param[0] (out value) - value.a: RNG data-rate in bytes per second
+ *                        value.b: Quality/Entropy per 1024 bit of data
+ * param[1] unused
+ * param[2] unused
+ * param[3] unused
+ *
+ * Result:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ */
+#define TA_CMD_GET_RNG_INFO		0x1
+
+#define MAX_ENTROPY_REQ_SZ		(4 * 1024)
+
+static struct tee_context *ctx;
+static struct tee_shm *entropy_shm_pool;
+static u32 ta_rng_data_rate;
+static u32 ta_rng_session_id;
+
+static size_t get_optee_rng_data(void *buf, size_t req_size)
+{
+	u32 ret = 0;
+	u8 *rng_data = NULL;
+	size_t rng_size = 0;
+	struct tee_ioctl_invoke_arg inv_arg = {0};
+	struct tee_param param[4] = {0};
+
+	/* Invoke TA_CMD_GET_ENTROPY function of Trusted App */
+	inv_arg.func = TA_CMD_GET_ENTROPY;
+	inv_arg.session = ta_rng_session_id;
+	inv_arg.num_params = 4;
+
+	/* Fill invoke cmd params */
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT;
+	param[0].u.memref.shm = entropy_shm_pool;
+	param[0].u.memref.size = req_size;
+	param[0].u.memref.shm_offs = 0;
+
+	ret = tee_client_invoke_func(ctx, &inv_arg, param);
+	if ((ret < 0) || (inv_arg.ret != 0)) {
+		pr_err("TA_CMD_GET_ENTROPY invoke function error: %x\n",
+		       inv_arg.ret);
+		return 0;
+	}
+
+	rng_data = tee_shm_get_va(entropy_shm_pool, 0);
+	if (IS_ERR(rng_data)) {
+		pr_err("tee_shm_get_va failed\n");
+		return 0;
+	}
+
+	rng_size = param[0].u.memref.size;
+	memcpy(buf, rng_data, rng_size);
+
+	return rng_size;
+}
+
+static int optee_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	u8 *data = buf;
+	size_t read = 0, rng_size = 0;
+	int timeout = 1;
+
+	if (max > MAX_ENTROPY_REQ_SZ)
+		max = MAX_ENTROPY_REQ_SZ;
+
+	while (read == 0) {
+		rng_size = get_optee_rng_data(data, (max - read));
+
+		data += rng_size;
+		read += rng_size;
+
+		if (wait) {
+			if (timeout-- == 0)
+				return read;
+			msleep((1000 * (max - read)) / ta_rng_data_rate);
+		} else {
+			return read;
+		}
+	}
+
+	return read;
+}
+
+static int optee_rng_init(struct hwrng *rng)
+{
+	entropy_shm_pool = tee_shm_alloc(ctx, MAX_ENTROPY_REQ_SZ,
+					 TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
+	if (IS_ERR(entropy_shm_pool)) {
+		pr_err("tee_shm_alloc failed\n");
+		return PTR_ERR(entropy_shm_pool);
+	}
+
+	return 0;
+}
+
+static void optee_rng_cleanup(struct hwrng *rng)
+{
+	tee_shm_free(entropy_shm_pool);
+}
+
+static struct hwrng optee_rng = {
+	.name		= DRIVER_NAME,
+	.init		= optee_rng_init,
+	.cleanup	= optee_rng_cleanup,
+	.read		= optee_rng_read,
+};
+
+static int get_optee_rng_info(struct device *dev)
+{
+	u32 ret = 0;
+	struct tee_ioctl_invoke_arg inv_arg = {0};
+	struct tee_param param[4] = {0};
+
+	/* Invoke TA_CMD_GET_RNG_INFO function of Trusted App */
+	inv_arg.func = TA_CMD_GET_RNG_INFO;
+	inv_arg.session = ta_rng_session_id;
+	inv_arg.num_params = 4;
+
+	/* Fill invoke cmd params */
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
+
+	ret = tee_client_invoke_func(ctx, &inv_arg, param);
+	if ((ret < 0) || (inv_arg.ret != 0)) {
+		dev_err(dev, "TA_CMD_GET_RNG_INFO invoke func error: %x\n",
+			inv_arg.ret);
+		return -EINVAL;
+	}
+
+	ta_rng_data_rate = param[0].u.value.a;
+	optee_rng.quality = param[0].u.value.b;
+
+	return 0;
+}
+
+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 optee_rng_probe(struct device *dev)
+{
+	struct tee_client_device *rng_device = to_tee_client_device(dev);
+	int ret = 0, err = -ENODEV;
+	struct tee_ioctl_open_session_arg sess_arg = {0};
+
+	/* Open context with TEE driver */
+	ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL);
+	if (IS_ERR(ctx))
+		return -ENODEV;
+
+	/* Open session with hwrng Trusted App */
+	memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
+	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
+	sess_arg.num_params = 0;
+
+	ret = tee_client_open_session(ctx, &sess_arg, NULL);
+	if ((ret < 0) || (sess_arg.ret != 0)) {
+		dev_err(dev, "tee_client_open_session failed, error: %x\n",
+			sess_arg.ret);
+		err = -EINVAL;
+		goto out_ctx;
+	}
+	ta_rng_session_id = sess_arg.session;
+
+	err = get_optee_rng_info(dev);
+	if (err)
+		goto out_sess;
+
+	err = hwrng_register(&optee_rng);
+	if (err) {
+		dev_err(dev, "hwrng registration failed (%d)\n", err);
+		goto out_sess;
+	}
+
+	return 0;
+
+out_sess:
+	tee_client_close_session(ctx, ta_rng_session_id);
+out_ctx:
+	tee_client_close_context(ctx);
+
+	return err;
+}
+
+static int optee_rng_remove(struct device *dev)
+{
+	tee_client_close_session(ctx, ta_rng_session_id);
+	tee_client_close_context(ctx);
+	hwrng_unregister(&optee_rng);
+
+	return 0;
+}
+
+const struct tee_client_device_id optee_rng_id_table[] = {
+	{UUID_INIT(0xab7a617c, 0xb8e7, 0x4d8f,
+		   0x83, 0x01, 0xd0, 0x9b, 0x61, 0x03, 0x6b, 0x64)},
+	{}
+};
+
+static struct tee_client_driver optee_rng_driver = {
+	.id_table	= optee_rng_id_table,
+	.driver		= {
+		.name		= DRIVER_NAME,
+		.bus		= &tee_bus_type,
+		.probe		= optee_rng_probe,
+		.remove		= optee_rng_remove,
+	},
+};
+
+static int __init optee_rng_mod_init(void)
+{
+	int rc;
+
+	rc = driver_register(&optee_rng_driver.driver);
+	if (rc)
+		pr_warn("driver registration failed, err: %d", rc);
+
+	return rc;
+}
+
+static void __exit optee_rng_mod_exit(void)
+{
+	driver_unregister(&optee_rng_driver.driver);
+}
+
+module_init(optee_rng_mod_init);
+module_exit(optee_rng_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sumit Garg <sumit.garg@linaro.org>");
+MODULE_DESCRIPTION("OP-TEE based random number generator driver");
-- 
2.7.4


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Re: [PATCH v3 1/4] tee: add bus driver framework for TEE based devices

[Bhupesh Sharma]

Hi Sumit,

Thanks for the patch. Some nitpicks in-line:

On 01/11/2019 05:17 PM, Sumit Garg wrote:
> Introduce a generic TEE bus driver concept for TEE based kernel drivers
> which would like to communicate with TEE based devices/services.
> 
> In this TEE bus concept, devices/services are identified via Universally
> Unique Identifier (UUID) and drivers register a table of device UUIDs
> which they can support.
> 
> So this TEE bus framework registers a match() callback function which
> iterates over the driver UUID table to find a corresponding match for
> device UUID. If a match is found, then this particular device is probed
> via corresponding probe api registered by the driver. This process
> happens whenever a device or a driver is registered with TEE bus.
> 
> Also this framework allows for device enumeration to be specific to
> corresponding TEE implementation like OP-TEE etc.
> 
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> ---
>   drivers/tee/tee_core.c  | 43 ++++++++++++++++++++++++++++++++++++++++---
>   include/linux/tee_drv.h | 36 ++++++++++++++++++++++++++++++++++++
>   2 files changed, 76 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> index 7b2bb4c..a685940 100644
> --- a/drivers/tee/tee_core.c
> +++ b/drivers/tee/tee_core.c
> @@ -15,7 +15,6 @@
>   #define pr_fmt(fmt) "%s: " fmt, __func__
>   
>   #include <linux/cdev.h>
> -#include <linux/device.h>
>   #include <linux/fs.h>
>   #include <linux/idr.h>
>   #include <linux/module.h>
> @@ -1027,6 +1026,30 @@ int tee_client_invoke_func(struct tee_context *ctx,
>   }
>   EXPORT_SYMBOL_GPL(tee_client_invoke_func);
>   
> +static int tee_client_device_match(struct device *dev,
> +				   struct device_driver *drv)
> +{
> +	struct tee_client_device *tee_device;
> +	const struct tee_client_device_id *id_table;
> +
> +	tee_device = to_tee_client_device(dev);
> +	id_table = to_tee_client_driver(drv)->id_table;
> +
> +	while (!uuid_is_null(&id_table->uuid)) {
> +		if (uuid_equal(&tee_device->id.uuid, &id_table->uuid))
> +			return 1;
> +		id_table++;
> +	}
> +
> +	return 0;
> +}
> +
> +struct bus_type tee_bus_type = {
> +	.name		= "tee",
> +	.match		= tee_client_device_match,
> +};
> +EXPORT_SYMBOL_GPL(tee_bus_type);
> +
>   static int __init tee_init(void)
>   {
>   	int rc;
> @@ -1040,10 +1063,23 @@ static int __init tee_init(void)
>   	rc = alloc_chrdev_region(&tee_devt, 0, TEE_NUM_DEVICES, "tee");
>   	if (rc) {
>   		pr_err("failed to allocate char dev region\n");
> -		class_destroy(tee_class);
> -		tee_class = NULL;
> +		goto chrdev_err;
>   	}
>   
> +	rc = bus_register(&tee_bus_type);
> +	if (rc) {
> +		pr_err("failed to register tee bus\n");
> +		goto bus_err;
> +	}
> +
> +	return 0;
> +
> +bus_err:
> +	unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
> +chrdev_err:
> +	class_destroy(tee_class);
> +	tee_class = NULL;
> +

Hmm.. these error paths/labels look out-of-order.
See 'drivers/i2c/i2c-dev.c' for example.

Normally our error paths in an __init function is of the same order as 
the __exit function implementation. So this should be changed to 
something like:

   +out_unreg_class:
   +	class_destroy(tee_class);
   +	tee_class = NULL;
   +out_unreg_chrdev:
   +	unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);

>   	return rc;
>   }
>   
> @@ -1052,6 +1088,7 @@ static void __exit tee_exit(void)
>   	class_destroy(tee_class);
>   	tee_class = NULL;
>   	unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
> +	bus_unregister(&tee_bus_type);

Since the __exit function order is the reverse of the __init one, lets 
reorder this as:

  +	bus_unregister(&tee_bus_type);
   	class_destroy(tee_class);
    	tee_class = NULL;
    	unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);

See 'drivers/i2c/i2c-dev.c' for example.

>   }
>   
>   subsys_initcall(tee_init);
> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> index 6cfe058..ed16bf1 100644
> --- a/include/linux/tee_drv.h
> +++ b/include/linux/tee_drv.h
> @@ -20,6 +20,8 @@
>   #include <linux/kref.h>
>   #include <linux/list.h>
>   #include <linux/tee.h>
> +#include <linux/device.h>
> +#include <linux/uuid.h>

If possible, let's keep alphabetical order of header files when making 
changes in the patch.

>   
>   /*
>    * The file describes the API provided by the generic TEE driver to the
> @@ -538,4 +540,38 @@ static inline bool tee_param_is_memref(struct tee_param *param)
>   	}
>   }
>   
> +extern struct bus_type tee_bus_type;
> +
> +/**
> + * struct tee_client_device_id - tee based device identifier
> + * @uuid:		For TEE based client devices we use the device uuid
> + *			as the identifier.
> + */
> +struct tee_client_device_id {
> +	uuid_t uuid;
> +};

Hmm.. Do we really need a struct for a single element, rather lets use a 
simple typedef here.

> +
> +/**
> + * struct tee_client_device - tee based device
> + * @id:			device identifier
> + * @dev:		device structure
> + */
> +struct tee_client_device {
> +	struct tee_client_device_id id;
> +	struct device dev;
> +};

Add a blank line here.

> +#define to_tee_client_device(d) container_of(d, struct tee_client_device, dev)
> +
> +/**
> + * struct tee_client_driver - tee client driver
> + * @id_table:		device id table supported by this driver
> + * @driver:		driver structure
> + */
> +struct tee_client_driver {
> +	const struct tee_client_device_id *id_table;
> +	struct device_driver driver;
> +};

Add a blank line here.
> +#define to_tee_client_driver(d) \
> +		container_of(d, struct tee_client_driver, driver)
> +
>   #endif /*__TEE_DRV_H*/
> 

Thanks,
Bhupesh

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Re: [PATCH v3 1/4] tee: add bus driver framework for TEE based devices

[Sumit Garg]

On Fri, 11 Jan 2019 at 20:39, Bhupesh Sharma <bhsharma@redhat.com> wrote:
>
> Hi Sumit,
>
> Thanks for the patch. Some nitpicks in-line:
>

Apologies for delay in my response as I was on leave. Please find my
comments inline.

Will include these nitpicks in v4 but let me wait for any further
major comments.

> On 01/11/2019 05:17 PM, Sumit Garg wrote:
> > Introduce a generic TEE bus driver concept for TEE based kernel drivers
> > which would like to communicate with TEE based devices/services.
> >
> > In this TEE bus concept, devices/services are identified via Universally
> > Unique Identifier (UUID) and drivers register a table of device UUIDs
> > which they can support.
> >
> > So this TEE bus framework registers a match() callback function which
> > iterates over the driver UUID table to find a corresponding match for
> > device UUID. If a match is found, then this particular device is probed
> > via corresponding probe api registered by the driver. This process
> > happens whenever a device or a driver is registered with TEE bus.
> >
> > Also this framework allows for device enumeration to be specific to
> > corresponding TEE implementation like OP-TEE etc.
> >
> > Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> > ---
> >   drivers/tee/tee_core.c  | 43 ++++++++++++++++++++++++++++++++++++++++---
> >   include/linux/tee_drv.h | 36 ++++++++++++++++++++++++++++++++++++
> >   2 files changed, 76 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> > index 7b2bb4c..a685940 100644
> > --- a/drivers/tee/tee_core.c
> > +++ b/drivers/tee/tee_core.c
> > @@ -15,7 +15,6 @@
> >   #define pr_fmt(fmt) "%s: " fmt, __func__
> >
> >   #include <linux/cdev.h>
> > -#include <linux/device.h>
> >   #include <linux/fs.h>
> >   #include <linux/idr.h>
> >   #include <linux/module.h>
> > @@ -1027,6 +1026,30 @@ int tee_client_invoke_func(struct tee_context *ctx,
> >   }
> >   EXPORT_SYMBOL_GPL(tee_client_invoke_func);
> >
> > +static int tee_client_device_match(struct device *dev,
> > +                                struct device_driver *drv)
> > +{
> > +     struct tee_client_device *tee_device;
> > +     const struct tee_client_device_id *id_table;
> > +
> > +     tee_device = to_tee_client_device(dev);
> > +     id_table = to_tee_client_driver(drv)->id_table;
> > +
> > +     while (!uuid_is_null(&id_table->uuid)) {
> > +             if (uuid_equal(&tee_device->id.uuid, &id_table->uuid))
> > +                     return 1;
> > +             id_table++;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +struct bus_type tee_bus_type = {
> > +     .name           = "tee",
> > +     .match          = tee_client_device_match,
> > +};
> > +EXPORT_SYMBOL_GPL(tee_bus_type);
> > +
> >   static int __init tee_init(void)
> >   {
> >       int rc;
> > @@ -1040,10 +1063,23 @@ static int __init tee_init(void)
> >       rc = alloc_chrdev_region(&tee_devt, 0, TEE_NUM_DEVICES, "tee");
> >       if (rc) {
> >               pr_err("failed to allocate char dev region\n");
> > -             class_destroy(tee_class);
> > -             tee_class = NULL;
> > +             goto chrdev_err;
> >       }
> >
> > +     rc = bus_register(&tee_bus_type);
> > +     if (rc) {
> > +             pr_err("failed to register tee bus\n");
> > +             goto bus_err;
> > +     }
> > +
> > +     return 0;
> > +
> > +bus_err:
> > +     unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
> > +chrdev_err:
> > +     class_destroy(tee_class);
> > +     tee_class = NULL;
> > +
>
> Hmm.. these error paths/labels look out-of-order.
> See 'drivers/i2c/i2c-dev.c' for example.
>
> Normally our error paths in an __init function is of the same order as
> the __exit function implementation. So this should be changed to
> something like:
>
>    +out_unreg_class:
>    +    class_destroy(tee_class);
>    +    tee_class = NULL;
>    +out_unreg_chrdev:
>    +    unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
>

It seems that prior to this patch also allocation order in __init
function differed from release order in __exit function. Will correct
that too along with this.

> >       return rc;
> >   }
> >
> > @@ -1052,6 +1088,7 @@ static void __exit tee_exit(void)
> >       class_destroy(tee_class);
> >       tee_class = NULL;
> >       unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
> > +     bus_unregister(&tee_bus_type);
>
> Since the __exit function order is the reverse of the __init one, lets
> reorder this as:
>
>   +     bus_unregister(&tee_bus_type);
>         class_destroy(tee_class);
>         tee_class = NULL;
>         unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
>

Ok.

> See 'drivers/i2c/i2c-dev.c' for example.
>
> >   }
> >
> >   subsys_initcall(tee_init);
> > diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> > index 6cfe058..ed16bf1 100644
> > --- a/include/linux/tee_drv.h
> > +++ b/include/linux/tee_drv.h
> > @@ -20,6 +20,8 @@
> >   #include <linux/kref.h>
> >   #include <linux/list.h>
> >   #include <linux/tee.h>
> > +#include <linux/device.h>
> > +#include <linux/uuid.h>
>
> If possible, let's keep alphabetical order of header files when making
> changes in the patch.
>

Ok.

> >
> >   /*
> >    * The file describes the API provided by the generic TEE driver to the
> > @@ -538,4 +540,38 @@ static inline bool tee_param_is_memref(struct tee_param *param)
> >       }
> >   }
> >
> > +extern struct bus_type tee_bus_type;
> > +
> > +/**
> > + * struct tee_client_device_id - tee based device identifier
> > + * @uuid:            For TEE based client devices we use the device uuid
> > + *                   as the identifier.
> > + */
> > +struct tee_client_device_id {
> > +     uuid_t uuid;
> > +};
>
> Hmm.. Do we really need a struct for a single element, rather lets use a
> simple typedef here.
>

Agree, will rather use typedef here.

> > +
> > +/**
> > + * struct tee_client_device - tee based device
> > + * @id:                      device identifier
> > + * @dev:             device structure
> > + */
> > +struct tee_client_device {
> > +     struct tee_client_device_id id;
> > +     struct device dev;
> > +};
>
> Add a blank line here.
>

Ok.

> > +#define to_tee_client_device(d) container_of(d, struct tee_client_device, dev)
> > +
> > +/**
> > + * struct tee_client_driver - tee client driver
> > + * @id_table:                device id table supported by this driver
> > + * @driver:          driver structure
> > + */
> > +struct tee_client_driver {
> > +     const struct tee_client_device_id *id_table;
> > +     struct device_driver driver;
> > +};
>
> Add a blank line here.

Ok.

-Sumit

> > +#define to_tee_client_driver(d) \
> > +             container_of(d, struct tee_client_driver, driver)
> > +
> >   #endif /*__TEE_DRV_H*/
> >
>
> Thanks,
> Bhupesh

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