usb: gadget: composite: Add usb_remove_config

This allows composite drivers to dynamically change their configuration.
For example, a driver might remove a configuration and register a new
one with a different set of functions.
User should prevent the host from enumerating the device while changing
the configuration:

	usb_gadget_disconnect(cdev->gadget);
	usb_remove_config(cdev, old_config);
	usb_add_config(cdev, new_config, new_conf_bind);
	usb_gadget_connect(cdev->gadget);

Change-Id: Icbfb4ce41685fde9bf63d5d58fca1ad242aa69f9
Signed-off-by: Benoit Goby <benoit@android.com>

1 files changed, 40 insertions, 20 deletions

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 5c06de61269a..98d0e3082342 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -904,6 +904,45 @@ done:
 	return status;
 }
 
+static int remove_config(struct usb_composite_dev *cdev,
+			      struct usb_configuration *config)
+{
+	while (!list_empty(&config->functions)) {
+		struct usb_function		*f;
+
+		f = list_first_entry(&config->functions,
+				struct usb_function, list);
+		list_del(&f->list);
+		if (f->unbind) {
+			DBG(cdev, "unbind function '%s'/%p\n", f->name, f);
+			f->unbind(config, f);
+			/* may free memory for "f" */
+		}
+	}
+	list_del(&config->list);
+	if (config->unbind) {
+		DBG(cdev, "unbind config '%s'/%p\n", config->label, config);
+		config->unbind(config);
+			/* may free memory for "c" */
+	}
+	return 0;
+}
+
+int usb_remove_config(struct usb_composite_dev *cdev,
+		      struct usb_configuration *config)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&cdev->lock, flags);
+
+	if (cdev->config == config)
+		reset_config(cdev);
+
+	spin_unlock_irqrestore(&cdev->lock, flags);
+
+	return remove_config(cdev, config);
+}
+
 /*-------------------------------------------------------------------------*/
 
 /* We support strings in multiple languages ... string descriptor zero
@@ -1504,28 +1543,9 @@ composite_unbind(struct usb_gadget *gadget)
 
 	while (!list_empty(&cdev->configs)) {
 		struct usb_configuration	*c;
-
 		c = list_first_entry(&cdev->configs,
 				struct usb_configuration, list);
-		while (!list_empty(&c->functions)) {
-			struct usb_function		*f;
-
-			f = list_first_entry(&c->functions,
-					struct usb_function, list);
-			list_del(&f->list);
-			if (f->unbind) {
-				DBG(cdev, "unbind function '%s'/%p\n",
-						f->name, f);
-				f->unbind(c, f);
-				/* may free memory for "f" */
-			}
-		}
-		list_del(&c->list);
-		if (c->unbind) {
-			DBG(cdev, "unbind config '%s'/%p\n", c->label, c);
-			c->unbind(c);
-			/* may free memory for "c" */
-		}
+		remove_config(cdev, c);
 	}
 	if (composite->unbind)
 		composite->unbind(cdev);