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

Message ID 1547207251-9372-2-git-send-email-sumit.garg@linaro.org
State New
Headers show
Series
  • Introduce TEE bus driver framework
Related show

Commit Message

Sumit Garg Jan. 11, 2019, 11:47 a.m.
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(-)

-- 
2.7.4

Comments

Sumit Garg Jan. 15, 2019, 11:53 a.m. | #1
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

Patch

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*/