usb: gadget: uvc: Minimize #include in headers

In order to speed up compilation, only include the headers that are
strictly required within other headers. To that end, use forward
structure declaration and move #include statements to .c file as
appropriate.

While at it, sort headers alphabetically, and remove unneeded __KERNEL__
guards.

Signed-off-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/function/f_uvc.c

···
  *	    Laurent Pinchart ([e-mail])
  */
 
-#include <linux/kernel.h>
-#include <linux/module.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
+#include <linux/kernel.h>
 #include <linux/list.h>
+#include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/string.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
+#include <linux/usb/g_uvc.h>
 #include <linux/usb/video.h>
 #include <linux/vmalloc.h>
 #include <linux/wait.h>

drivers/usb/gadget/function/f_uvc.h

···
 #ifndef _F_UVC_H_
 #define _F_UVC_H_
 
-#include <linux/usb/composite.h>
-#include <linux/usb/video.h>
-
-#include "uvc.h"
+struct uvc_device;
 
 void uvc_function_setup_continue(struct uvc_device *uvc);
 
···
 void uvc_function_disconnect(struct uvc_device *uvc);
 
 #endif /* _F_UVC_H_ */
-

drivers/usb/gadget/function/u_uvc.h

···
 #ifndef U_UVC_H
 #define U_UVC_H
 
+#include <linux/mutex.h>
 #include <linux/usb/composite.h>
 #include <linux/usb/video.h>
 

drivers/usb/gadget/function/uvc.h

···
 #ifndef _UVC_GADGET_H_
 #define _UVC_GADGET_H_
 
-#include <linux/usb.h>	/* For usb_endpoint_* */
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
 #include <linux/usb/composite.h>
-#include <linux/usb/gadget.h>
-#include <linux/usb/g_uvc.h>
 #include <linux/videodev2.h>
-#include <media/v4l2-fh.h>
+
 #include <media/v4l2-device.h>
+#include <media/v4l2-dev.h>
+#include <media/v4l2-fh.h>
 
 #include "uvc_queue.h"
+
+struct usb_ep;
+struct usb_request;
+struct uvc_descriptor_header;
 
 /* ------------------------------------------------------------------------
  * Debugging, printing and logging

drivers/usb/gadget/function/uvc_queue.h

···
 #ifndef _UVC_QUEUE_H_
 #define _UVC_QUEUE_H_
 
-#ifdef __KERNEL__
-
-#include <linux/kernel.h>
+#include <linux/list.h>
 #include <linux/poll.h>
-#include <linux/videodev2.h>
+#include <linux/spinlock.h>
+
 #include <media/videobuf2-v4l2.h>
+
+struct file;
+struct mutex;
 
 /* Maximum frame size in bytes, for sanity checking. */
 #define UVC_MAX_FRAME_SIZE	(16*1024*1024)
···
 					  struct uvc_buffer *buf);
 
 struct uvc_buffer *uvcg_queue_head(struct uvc_video_queue *queue);
-
-#endif /* __KERNEL__ */
 
 #endif /* _UVC_QUEUE_H_ */
 

drivers/usb/gadget/function/uvc_v4l2.c

···
  *	    Laurent Pinchart ([e-mail])
  */
 
-#include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/errno.h>
+#include <linux/kernel.h>
 #include <linux/list.h>
+#include <linux/usb/g_uvc.h>
 #include <linux/videodev2.h>
 #include <linux/vmalloc.h>
 #include <linux/wait.h>

drivers/usb/gadget/function/uvc_video.h

···
 #ifndef __UVC_VIDEO_H__
 #define __UVC_VIDEO_H__
 
+struct uvc_video;
+
 int uvcg_video_pump(struct uvc_video *video);
 
 int uvcg_video_enable(struct uvc_video *video, int enable);