usb: gadget: composite: add req_match method to usb_function

Non-standard requests can encode the actual interface number in a
non-standard way. For example composite_setup() assumes
that it is w_index && 0xFF, but the printer function encodes the interface
number in a context-dependet way (either w_index or w_index >> 8).
This can lead to such requests being directed to wrong functions.

This patch adds req_match() method to usb_function. Its purpose is to
verify that a given request can be handled by a given function.
If any function within a configuration provides the method and it returns
true, then it is assumed that the right function is found.

If a function uses req_match(), it should try as hard as possible to
determine if the request is meant for it.

If no functions in a configuration provide req_match or none of them
returns true, then fall back to the usual approach.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index 3d87defcc527..2511469a9904 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -148,6 +148,7 @@ struct usb_os_desc_table {
  * @disable: (REQUIRED) Indicates the function should be disabled.  Reasons
  *	include host resetting or reconfiguring the gadget, and disconnection.
  * @setup: Used for interface-specific control requests.
+ * @req_match: Tests if a given class request can be handled by this function.
  * @suspend: Notifies functions when the host stops sending USB traffic.
  * @resume: Notifies functions when the host restarts USB traffic.
  * @get_status: Returns function status as a reply to
@@ -213,6 +214,8 @@ struct usb_function {
 	void			(*disable)(struct usb_function *);
 	int			(*setup)(struct usb_function *,
 					const struct usb_ctrlrequest *);
+	bool			(*req_match)(struct usb_function *,
+					const struct usb_ctrlrequest *);
 	void			(*suspend)(struct usb_function *);
 	void			(*resume)(struct usb_function *);