USB: Composite framework: Add suspended sysfs entry

This patch adds a sysfs entry (/sys/devices/platform/_UDC_/gadget/suspended) to
show the suspend state of an USB composite gadget.
Signed-off-by: Fabien Chouteau <fabien.chouteau@barco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/ABI/testing/sysfs-devices-platform-_UDC_-gadget

+What:		/sys/devices/platform/_UDC_/gadget/suspended
+Date:		April 2010
+Contact:	Fabien Chouteau <fabien.chouteau@barco.com>
+Description:
+		Show the suspend state of an USB composite gadget.
+		1 -> suspended
+		0 -> resumed
+
+		(_UDC_ is the name of the USB Device Controller driver)

drivers/usb/gadget/composite.c

@@ -898,6 +898,18 @@ static void composite_disconnect(struct usb_gadget *gadget)
 
 /*-------------------------------------------------------------------------*/
 
+static ssize_t composite_show_suspended(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct usb_gadget *gadget = dev_to_usb_gadget(dev);
+	struct usb_composite_dev *cdev = get_gadget_data(gadget);
+
+	return sprintf(buf, "%d\n", cdev->suspended);
+}
+
+static DEVICE_ATTR(suspended, 0444, composite_show_suspended, NULL);
+
 static void /* __init_or_exit */
 composite_unbind(struct usb_gadget *gadget)
 {
@@ -944,6 +956,7 @@ composite_unbind(struct usb_gadget *gadget)
 	}
 	kfree(cdev);
 	set_gadget_data(gadget, NULL);
+	device_remove_file(&gadget->dev, &dev_attr_suspended);
 	composite = NULL;
 }
 
@@ -1036,6 +1049,10 @@ static int __init composite_bind(struct usb_gadget *gadget)
 		string_override(composite->strings,
 			cdev->desc.iSerialNumber, iSerialNumber);
 
+	status = device_create_file(&gadget->dev, &dev_attr_suspended);
+	if (status)
+		goto fail;
+
 	INFO(cdev, "%s ready\n", composite->name);
 	return 0;
 
@@ -1064,6 +1081,8 @@ composite_suspend(struct usb_gadget *gadget)
 	}
 	if (composite->suspend)
 		composite->suspend(cdev);
+
+	cdev->suspended = 1;
 }
 
 static void
@@ -1084,6 +1103,8 @@ composite_resume(struct usb_gadget *gadget)
 				f->resume(f);
 		}
 	}
+
+	cdev->suspended = 0;
 }
 
 /*-------------------------------------------------------------------------*/

include/linux/usb/composite.h

@@ -326,6 +326,7 @@ struct usb_composite_dev {
 
 	/* private: */
 	/* internals */
+	unsigned int			suspended:1;
 	struct usb_device_descriptor	desc;
 	struct list_head		configs;
 	struct usb_composite_driver	*driver;

include/linux/usb/gadget.h

@@ -494,6 +494,10 @@ 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)
 	{ return dev_get_drvdata(&gadget->dev); }
+static inline struct usb_gadget *dev_to_usb_gadget(struct device *dev)
+{
+	return container_of(dev, struct usb_gadget, dev);
+}
 
 /* iterates the non-control endpoints; 'tmp' is a struct usb_ep pointer */
 #define gadget_for_each_ep(tmp,gadget) \