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>

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 5465d87..f9aff1b 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -898,6 +898,18 @@
 
 /*-------------------------------------------------------------------------*/
 
+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 @@
 	}
 	kfree(cdev);
 	set_gadget_data(gadget, NULL);
+	device_remove_file(&gadget->dev, &dev_attr_suspended);
 	composite = NULL;
 }
 
@@ -1036,6 +1049,10 @@
 		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 @@
 	}
 	if (composite->suspend)
 		composite->suspend(cdev);
+
+	cdev->suspended = 1;
 }
 
 static void
@@ -1084,6 +1103,8 @@
 				f->resume(f);
 		}
 	}
+
+	cdev->suspended = 0;
 }
 
 /*-------------------------------------------------------------------------*/