[PATCH RFC 2/4] USB: UDC: Expand device model API interface

[Alan Stern <stern@rowland.harvard.edu>]

The routines used by the UDC core to interface with the kernel's
device model, namely usb_add_gadget_udc(),
usb_add_gadget_udc_release(), and usb_del_gadget_udc(), provide access
to only a subset of the device model's full API.  They include
functionality equivalent to device_register() and device_unregister()
for gadgets, but they omit device_initialize(), device_add(),
device_del(), get_device(), and put_device().

This patch expands the UDC API by adding usb_initialize_gadget(),
usb_add_gadget(), usb_del_gadget(), usb_get_gadget(), and
usb_put_gadget() to fill in the gap.  It rewrites the existing
routines to call the new ones.

The next patches in this series fix longstanding problems in the
net2280 and net2272 UDC drivers by making use of the expanded API.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Anton Vasilyev <vasilyev@ispras.ru>
CC: Evgeny Novikov <novikov@ispras.ru>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>

---

 drivers/usb/gadget/udc/core.c |   78 +++++++++++++++++++++++++++++++++---------
 include/linux/usb/gadget.h    |   27 +++++++++++---
 2 files changed, 84 insertions(+), 21 deletions(-)


Index: usb-devel/include/linux/usb/gadget.h
===================================================================
--- usb-devel.orig/include/linux/usb/gadget.h
+++ usb-devel/include/linux/usb/gadget.h
@@ -435,6 +435,7 @@ struct usb_gadget {
 };
 #define work_to_gadget(w)	(container_of((w), struct usb_gadget, work))
 
+/* Interface to the device model */
 static inline void set_gadget_data(struct usb_gadget *gadget, void *data)
 	{ dev_set_drvdata(&gadget->dev, data); }
 static inline void *get_gadget_data(struct usb_gadget *gadget)
@@ -443,6 +444,26 @@ static inline struct usb_gadget *dev_to_
 {
 	return container_of(dev, struct usb_gadget, dev);
 }
+static inline struct usb_gadget *usb_get_gadget(struct usb_gadget *gadget)
+{
+	get_device(&gadget->dev);
+	return gadget;
+}
+static inline void usb_put_gadget(struct usb_gadget *gadget)
+{
+	put_device(&gadget->dev);
+}
+extern void usb_initialize_gadget(struct device *parent,
+		struct usb_gadget *gadget, void (*release)(struct device *dev));
+extern int usb_add_gadget(struct usb_gadget *gadget);
+extern void usb_del_gadget(struct usb_gadget *gadget);
+
+/* Legacy device-model interface */
+extern int usb_add_gadget_udc_release(struct device *parent,
+		struct usb_gadget *gadget, void (*release)(struct device *dev));
+extern int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget);
+extern void usb_del_gadget_udc(struct usb_gadget *gadget);
+extern char *usb_get_gadget_udc_name(void);
 
 /* iterates the non-control endpoints; 'tmp' is a struct usb_ep pointer */
 #define gadget_for_each_ep(tmp, gadget) \
@@ -734,12 +755,6 @@ int usb_gadget_probe_driver(struct usb_g
  */
 int usb_gadget_unregister_driver(struct usb_gadget_driver *driver);
 
-extern int usb_add_gadget_udc_release(struct device *parent,
-		struct usb_gadget *gadget, void (*release)(struct device *dev));
-extern int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget);
-extern void usb_del_gadget_udc(struct usb_gadget *gadget);
-extern char *usb_get_gadget_udc_name(void);
-
 /*-------------------------------------------------------------------------*/
 
 /* utility to simplify dealing with string descriptors */
Index: usb-devel/drivers/usb/gadget/udc/core.c
===================================================================
--- usb-devel.orig/drivers/usb/gadget/udc/core.c
+++ usb-devel/drivers/usb/gadget/udc/core.c
@@ -1163,21 +1163,18 @@ static int check_pending_gadget_drivers(
 }
 
 /**
- * usb_add_gadget_udc_release - adds a new gadget to the udc class driver list
+ * usb_intialize_gadget - initialize a gadget and its embedded struct device
  * @parent: the parent device to this udc. Usually the controller driver's
  * device.
- * @gadget: the gadget to be added to the list.
+ * @gadget: the gadget to be initialized.
  * @release: a gadget release function.
  *
  * Returns zero on success, negative errno otherwise.
  * Calls the gadget release function in the latter case.
  */
-int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
+void usb_initialize_gadget(struct device *parent, struct usb_gadget *gadget,
 		void (*release)(struct device *dev))
 {
-	struct usb_udc		*udc;
-	int			ret = -ENOMEM;
-
 	dev_set_name(&gadget->dev, "gadget");
 	INIT_WORK(&gadget->work, usb_gadget_state_work);
 	gadget->dev.parent = parent;
@@ -1188,17 +1185,32 @@ int usb_add_gadget_udc_release(struct de
 		gadget->dev.release = usb_udc_zero_release;
 
 	device_initialize(&gadget->dev);
+}
+EXPORT_SYMBOL_GPL(usb_initialize_gadget);
+
+/**
+ * usb_add_gadget - adds a new gadget to the udc class driver list
+ * @gadget: the gadget to be added to the list.
+ *
+ * Returns zero on success, negative errno otherwise.
+ * Does not do a final usb_put_gadget() if an error occurs.
+ */
+int usb_add_gadget(struct usb_gadget *gadget)
+{
+	struct usb_udc		*udc;
+	int			ret = -ENOMEM;
 
 	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
 	if (!udc)
-		goto err_put_gadget;
+		goto error;
 
 	device_initialize(&udc->dev);
 	udc->dev.release = usb_udc_release;
 	udc->dev.class = udc_class;
 	udc->dev.groups = usb_udc_attr_groups;
-	udc->dev.parent = parent;
-	ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
+	udc->dev.parent = gadget->dev.parent;
+	ret = dev_set_name(&udc->dev, "%s",
+			kobject_name(&gadget->dev.parent->kobj));
 	if (ret)
 		goto err_put_udc;
 
@@ -1240,8 +1252,30 @@ int usb_add_gadget_udc_release(struct de
  err_put_udc:
 	put_device(&udc->dev);
 
- err_put_gadget:
-	put_device(&gadget->dev);
+ error:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_add_gadget);
+
+/**
+ * usb_add_gadget_udc_release - adds a new gadget to the udc class driver list
+ * @parent: the parent device to this udc. Usually the controller driver's
+ * device.
+ * @gadget: the gadget to be added to the list.
+ * @release: a gadget release function.
+ *
+ * Returns zero on success, negative errno otherwise.
+ * Calls the gadget release function in the latter case.
+ */
+int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
+		void (*release)(struct device *dev))
+{
+	int	ret;
+
+	usb_initialize_gadget(parent, gadget, release);
+	ret = usb_add_gadget(gadget);
+	if (ret)
+		usb_put_gadget(gadget);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(usb_add_gadget_udc_release);
@@ -1309,13 +1343,14 @@ static void usb_gadget_remove_driver(str
 }
 
 /**
- * usb_del_gadget_udc - deletes @udc from udc_list
+ * usb_del_gadget - deletes @udc from udc_list
  * @gadget: the gadget to be removed.
  *
- * This, will call usb_gadget_unregister_driver() if
+ * This will call usb_gadget_unregister_driver() if
  * the @udc is still busy.
+ * It will not do a final usb_put_gadget().
  */
-void usb_del_gadget_udc(struct usb_gadget *gadget)
+void usb_del_gadget(struct usb_gadget *gadget)
 {
 	struct usb_udc *udc = gadget->udc;
 
@@ -1338,7 +1373,20 @@ void usb_del_gadget_udc(struct usb_gadge
 	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
 	flush_work(&gadget->work);
 	device_unregister(&udc->dev);
-	device_unregister(&gadget->dev);
+	device_del(&gadget->dev);
+}
+EXPORT_SYMBOL_GPL(usb_del_gadget);
+
+/**
+ * usb_del_gadget_udc - deletes @udc from udc_list
+ * @gadget: the gadget to be removed.
+ *
+ * Calls usb_del_gadget() and does a final usb_put_gadget().
+ */
+void usb_del_gadget_udc(struct usb_gadget *gadget)
+{
+	usb_del_gadget(gadget);
+	usb_put_gadget(gadget);
 }
 EXPORT_SYMBOL_GPL(usb_del_gadget_udc);