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authorDavid Brownell <dbrownell@users.sourceforge.net>2008-08-18 17:38:22 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-17 14:40:53 -0700
commit60beed95e38793c0baff7f94433c1f639d8d5efd (patch)
treef35e277cdd32267772854b481843299564e4f3e8 /include/linux/usb/composite.h
parent8066134ff8140ae9d8d15cdad3fc6c60c2a8a4e5 (diff)
usb gadget: function activation/deactivation
Add a new mechanism to the composite gadget framework, letting functions deactivate (and reactivate) themselves. Think of it as a refcounted wrapper for the software pullup control. A key example of why to use this mechanism involves functions that require a userspace daemon. Those functions shuld use this new mechanism to prevent the gadget from enumerating until those daemons are activated. Without this mechanism, hosts would see devices that malfunction until the relevant daemons start. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include/linux/usb/composite.h')
-rw-r--r--include/linux/usb/composite.h11
1 files changed, 9 insertions, 2 deletions
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index c932390c6da..935c380ffe4 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -130,6 +130,9 @@ struct usb_function {
int usb_add_function(struct usb_configuration *, struct usb_function *);
+int usb_function_deactivate(struct usb_function *);
+int usb_function_activate(struct usb_function *);
+
int usb_interface_id(struct usb_configuration *, struct usb_function *);
/**
@@ -316,9 +319,13 @@ struct usb_composite_dev {
struct usb_composite_driver *driver;
u8 next_string_id;
- spinlock_t lock;
+ /* the gadget driver won't enable the data pullup
+ * while the deactivation count is nonzero.
+ */
+ unsigned deactivations;
- /* REVISIT use and existence of lock ... */
+ /* protects at least deactivation count */
+ spinlock_t lock;
};
extern int usb_string_id(struct usb_composite_dev *c);