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Subject[PATCH v6 1/4] tee: add bus driver framework for TEE based devices
Date
Introduce a generic TEE bus driver concept for TEE based kernel drivers
which would like to communicate with TEE based devices/services. Also
add support in module device table for these new TEE based devices.

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 following apis:
- match(): 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.
- uevent(): Notifies user-space (udev) whenever a new device is registered
on this bus for auto-loading of modularized drivers.

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>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
---
drivers/tee/tee_core.c | 54 ++++++++++++++++++++++++++++++++++++---
include/linux/mod_devicetable.h | 9 +++++++
include/linux/tee_drv.h | 32 ++++++++++++++++++++++-
scripts/mod/devicetable-offsets.c | 3 +++
scripts/mod/file2alias.c | 19 ++++++++++++++
5 files changed, 112 insertions(+), 5 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 7b2bb4c..1e14897 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 +1026,39 @@ 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)
+{
+ const struct tee_client_device_id *id_table;
+ struct tee_client_device *tee_device;
+
+ id_table = to_tee_client_driver(drv)->id_table;
+ tee_device = to_tee_client_device(dev);
+
+ while (!uuid_is_null(&id_table->uuid)) {
+ if (uuid_equal(&tee_device->id.uuid, &id_table->uuid))
+ return 1;
+ id_table++;
+ }
+
+ return 0;
+}
+
+static int tee_client_device_uevent(struct device *dev,
+ struct kobj_uevent_env *env)
+{
+ uuid_t *dev_id = &to_tee_client_device(dev)->id.uuid;
+
+ return add_uevent_var(env, "MODALIAS=tee:%pUb", dev_id);
+}
+
+struct bus_type tee_bus_type = {
+ .name = "tee",
+ .match = tee_client_device_match,
+ .uevent = tee_client_device_uevent,
+};
+EXPORT_SYMBOL_GPL(tee_bus_type);
+
static int __init tee_init(void)
{
int rc;
@@ -1040,18 +1072,32 @@ 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 out_unreg_class;
+ }
+
+ rc = bus_register(&tee_bus_type);
+ if (rc) {
+ pr_err("failed to register tee bus\n");
+ goto out_unreg_chrdev;
}

+ return 0;
+
+out_unreg_chrdev:
+ unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
+out_unreg_class:
+ class_destroy(tee_class);
+ tee_class = NULL;
+
return rc;
}

static void __exit tee_exit(void)
{
+ bus_unregister(&tee_bus_type);
+ unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
class_destroy(tee_class);
tee_class = NULL;
- unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
}

subsys_initcall(tee_init);
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index f9bd2f3..14eaeeb 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -779,4 +779,13 @@ struct typec_device_id {
kernel_ulong_t driver_data;
};

+/**
+ * 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;
+};
+
#endif /* LINUX_MOD_DEVICETABLE_H */
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 6cfe058..ce957ce 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -15,11 +15,14 @@
#ifndef __TEE_DRV_H
#define __TEE_DRV_H

-#include <linux/types.h>
+#include <linux/device.h>
#include <linux/idr.h>
#include <linux/kref.h>
#include <linux/list.h>
+#include <linux/mod_devicetable.h>
#include <linux/tee.h>
+#include <linux/types.h>
+#include <linux/uuid.h>

/*
* The file describes the API provided by the generic TEE driver to the
@@ -538,4 +541,31 @@ static inline bool tee_param_is_memref(struct tee_param *param)
}
}

+extern struct bus_type tee_bus_type;
+
+/**
+ * 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*/
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index 2930044..1607183 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -225,5 +225,8 @@ int main(void)
DEVID_FIELD(typec_device_id, svid);
DEVID_FIELD(typec_device_id, mode);

+ DEVID(tee_client_device_id);
+ DEVID_FIELD(tee_client_device_id, uuid);
+
return 0;
}
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index a37af7d..d0e4172 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -37,6 +37,9 @@ typedef unsigned char __u8;
typedef struct {
__u8 b[16];
} uuid_le;
+typedef struct {
+ __u8 b[16];
+} uuid_t;

/* Big exception to the "don't include kernel headers into userspace, which
* even potentially has different endianness and word sizes, since
@@ -1287,6 +1290,21 @@ static int do_typec_entry(const char *filename, void *symval, char *alias)
return 1;
}

+/* Looks like: tee:uuid */
+static int do_tee_entry(const char *filename, void *symval, char *alias)
+{
+ DEF_FIELD(symval, tee_client_device_id, uuid);
+
+ sprintf(alias, "tee:%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+ uuid.b[0], uuid.b[1], uuid.b[2], uuid.b[3], uuid.b[4],
+ uuid.b[5], uuid.b[6], uuid.b[7], uuid.b[8], uuid.b[9],
+ uuid.b[10], uuid.b[11], uuid.b[12], uuid.b[13], uuid.b[14],
+ uuid.b[15]);
+
+ add_wildcard(alias);
+ return 1;
+}
+
/* Does namelen bytes of name exactly match the symbol? */
static bool sym_is(const char *name, unsigned namelen, const char *symbol)
{
@@ -1357,6 +1375,7 @@ static const struct devtable devtable[] = {
{"fslmc", SIZE_fsl_mc_device_id, do_fsl_mc_entry},
{"tbsvc", SIZE_tb_service_id, do_tbsvc_entry},
{"typec", SIZE_typec_device_id, do_typec_entry},
+ {"tee", SIZE_tee_client_device_id, do_tee_entry},
};

/* Create MODULE_ALIAS() statements.
--
2.7.4
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