usb gadget: function activation/deactivation

[linux-2.6-omap-h63xx.git] / drivers / usb / gadget / composite.c

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 85c876c1f150b734eb2193e62760bb9f6b972785..f79fdb839cb8face68082e289d9d54cde4bee250 100644 (file)
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -127,6 +127,70 @@ done:
        return value;
 }
 
+/**
+ * usb_function_deactivate - prevent function and gadget enumeration
+ * @function: the function that isn't yet ready to respond
+ *
+ * Blocks response of the gadget driver to host enumeration by
+ * preventing the data line pullup from being activated.  This is
+ * normally called during @bind() processing to change from the
+ * initial "ready to respond" state, or when a required resource
+ * becomes available.
+ *
+ * For example, drivers that serve as a passthrough to a userspace
+ * daemon can block enumeration unless that daemon (such as an OBEX,
+ * MTP, or print server) is ready to handle host requests.
+ *
+ * Not all systems support software control of their USB peripheral
+ * data pullups.
+ *
+ * Returns zero on success, else negative errno.
+ */
+int usb_function_deactivate(struct usb_function *function)
+{
+       struct usb_composite_dev        *cdev = function->config->cdev;
+       int                             status = 0;
+
+       spin_lock(&cdev->lock);
+
+       if (cdev->deactivations == 0)
+               status = usb_gadget_disconnect(cdev->gadget);
+       if (status == 0)
+               cdev->deactivations++;
+
+       spin_unlock(&cdev->lock);
+       return status;
+}
+
+/**
+ * usb_function_activate - allow function and gadget enumeration
+ * @function: function on which usb_function_activate() was called
+ *
+ * Reverses effect of usb_function_deactivate().  If no more functions
+ * are delaying their activation, the gadget driver will respond to
+ * host enumeration procedures.
+ *
+ * Returns zero on success, else negative errno.
+ */
+int usb_function_activate(struct usb_function *function)
+{
+       struct usb_composite_dev        *cdev = function->config->cdev;
+       int                             status = 0;
+
+       spin_lock(&cdev->lock);
+
+       if (WARN_ON(cdev->deactivations == 0))
+               status = -EINVAL;
+       else {
+               cdev->deactivations--;
+               if (cdev->deactivations == 0)
+                       status = usb_gadget_connect(cdev->gadget);
+       }
+
+       spin_unlock(&cdev->lock);
+       return status;
+}
+
 /**
  * usb_interface_id() - allocate an unused interface ID
  * @config: configuration associated with the interface