45  * are two types of files.  One type is for the device, implementing ep0.
83 /* /dev/gadget/$CHIP represents ep0 and the whole device */
89 	 * ep0/device i/o modes and binding to the controller.  Driver
95 	/* From then on, ep0 fd is in either of two basic modes:
104 	/* UNBOUND means the driver closed ep0, so the device won't be
125 	/* drivers reading ep0 MUST handle control requests (SETUP)
148 	/* except this scratch i/o buffer for ep0 */
237  * at the end of ep0 configuration, or after unbind.
842 /* EP0 IMPLEMENTATION can be partly in userspace.
895 		DBG (dev, "ep0 request busy!\n");  in setup_req()
935 			(void) usb_ep_set_halt (dev->gadget->ep0);  in ep0_read()
940 			struct usb_ep		*ep = dev->gadget->ep0;  in ep0_read()
998 				clean_req (dev->gadget->ep0, dev->req);  in ep0_read()
1022 		/* ep0 i/o has special semantics during STATE_DEV_SETUP */  in ep0_read()
1038 			 * concurrent ep0 readers may lose events.  in ep0_read()
1138 			retval = setup_req (dev->gadget->ep0, dev->req, len);  in ep0_write()
1149 						dev->gadget->ep0, dev->req,  in ep0_write()
1155 					clean_req (dev->gadget->ep0, dev->req);  in ep0_write()
1165 			(void) usb_ep_set_halt (dev->gadget->ep0);  in ep0_write()
1193 	/* closing ep0 === shutdown all */  in dev_release()
1275 /* The in-kernel gadget driver handles most ep0 issues, in particular
1278  * Unrecognized ep0 requests may be handled in user space.
1295 	/* assumes ep0 uses the same value for both speeds ... */  in make_qualifier()
1296 	qual.bMaxPacketSize0 = dev->gadget->ep0->maxpacket;  in make_qualifier()
1389 			dev->dev->bMaxPacketSize0 = dev->gadget->ep0->maxpacket;  in gadgetfs_setup()
1479 		/* if there's an ep0 reader, don't stall */  in gadgetfs_setup()
1491 				value = setup_req (gadget->ep0, dev->req,  in gadgetfs_setup()
1498 				value = usb_ep_queue (gadget->ep0, dev->req,  in gadgetfs_setup()
1503 					clean_req (gadget->ep0, dev->req);  in gadgetfs_setup()
1527 		value = usb_ep_queue (gadget->ep0, req, GFP_KERNEL);  in gadgetfs_setup()
1653 	gadget->ep0->driver_data = NULL;  in gadgetfs_unbind()
1658 		usb_ep_free_request (gadget->ep0, dev->req);  in gadgetfs_unbind()
1680 	gadget->ep0->driver_data = dev;  in gadgetfs_bind()
1683 	dev->req = usb_ep_alloc_request (gadget->ep0, GFP_KERNEL);  in gadgetfs_bind()
1892 		 * kick in after the ep0 descriptor is closed.  in dev_config()
1950  * if epfiles inherited ownership and permissons from ep0 ...
2048 	/* the ep0 file is named after the controller we expect;  in gadgetfs_fill_super()