usbfs: Add support for allocating / freeing streams

This allows userspace to use bulk-streams, just like in kernel drivers, see
Documentation/usb/bulk-streams.txt for details on the in kernel API. This
is exported pretty much one on one to userspace.

To use streams an app must first make a USBDEVFS_ALLOC_STREAMS ioctl,
on success this will return the number of streams available (which may be
less then requested). If there are n streams the app can then submit
usbdevfs_urb-s with their stream_id member set to 1-n to use a specific
stream. IE if USBDEVFS_ALLOC_STREAMS returns 4 then stream_id 1-4 can be
used.

When the app is done using streams it should call USBDEVFS_FREE_STREAMS

Note applications are advised to use libusb rather then using the
usbdevfs api directly. The latest version of libusb has support for streams.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/uapi/linux/usbdevice_fs.h b/include/uapi/linux/usbdevice_fs.h
index cbf122db56bc..abe5f4bd4d82 100644
--- a/include/uapi/linux/usbdevice_fs.h
+++ b/include/uapi/linux/usbdevice_fs.h
@@ -147,6 +147,11 @@ struct usbdevfs_disconnect_claim {
         char driver[USBDEVFS_MAXDRIVERNAME + 1];
 };
 
+struct usbdevfs_streams {
+        unsigned int num_streams; /* Not used by USBDEVFS_FREE_STREAMS */
+        unsigned int num_eps;
+        unsigned char eps[0];
+};
 
 #define USBDEVFS_CONTROL           _IOWR('U', 0, struct usbdevfs_ctrltransfer)
 #define USBDEVFS_CONTROL32           _IOWR('U', 0, struct usbdevfs_ctrltransfer32)
@@ -179,5 +184,7 @@ struct usbdevfs_disconnect_claim {
 #define USBDEVFS_RELEASE_PORT      _IOR('U', 25, unsigned int)
 #define USBDEVFS_GET_CAPABILITIES  _IOR('U', 26, __u32)
 #define USBDEVFS_DISCONNECT_CLAIM  _IOR('U', 27, struct usbdevfs_disconnect_claim)
+#define USBDEVFS_ALLOC_STREAMS     _IOR('U', 28, struct usbdevfs_streams)
+#define USBDEVFS_FREE_STREAMS      _IOR('U', 29, struct usbdevfs_streams)
 
 #endif /* _UAPI_LINUX_USBDEVICE_FS_H */