static void mts_get_status( struct urb *transfer )
/* Interrupt context! */
{
	MTS_INT_INIT();

	mts_int_submit_urb(transfer,
			   usb_rcvbulkpipe(context->instance->usb_dev,
					   context->instance->ep_response),
			   &context->status,
			   1,
			   mts_transfer_done );
}

static void mts_data_done( struct urb* transfer )
/* Interrupt context! */
{
	MTS_INT_INIT();

	if ( context->data_length != transfer->actual_length ) {
		context->srb->resid = context->data_length - transfer->actual_length;
	} else if ( unlikely(transfer->status) ) {
		context->srb->result = (transfer->status == -ENOENT ? DID_ABORT : DID_ERROR)<<16;
	}

	mts_get_status(transfer);

	return;
}


static void mts_command_done( struct urb *transfer )
/* Interrupt context! */
{
	MTS_INT_INIT();

	if ( unlikely(transfer->status) ) {
	        if (transfer->status == -ENOENT) {
		        /* We are being killed */
			MTS_DEBUG_GOT_HERE();
			context->srb->result = DID_ABORT<<16;
                } else {
		        /* A genuine error has occured */
			MTS_DEBUG_GOT_HERE();

		        context->srb->result = DID_ERROR<<16;
                }
		mts_transfer_cleanup(transfer);

		return;
	}

	if ( context->data ) {
		mts_int_submit_urb(transfer,
				   context->data_pipe,
				   context->data,
				   context->data_length,
				   context->srb->use_sg ? mts_do_sg : mts_data_done);
	} else mts_get_status(transfer);

	return;
}

static void mts_do_sg (struct urb* transfer)
{
	struct scatterlist * sg;
	MTS_INT_INIT();
	
	MTS_DEBUG("Processing fragment %d of %d\n", context->fragment,context->srb->use_sg);

	if (unlikely(transfer->status)) {
                context->srb->result = (transfer->status == -ENOENT ? DID_ABORT : DID_ERROR)<<16;
		mts_transfer_cleanup(transfer);
        }

	sg = context->srb->buffer;
	context->fragment++;
	mts_int_submit_urb(transfer,
			   context->data_pipe,
			   page_address(sg[context->fragment].page) +
			   sg[context->fragment].offset,
			   sg[context->fragment].length,
			   context->fragment + 1 == context->srb->use_sg ? mts_data_done : mts_do_sg);
	return;
}

static const u8 mts_read_image_sig[] = { 0x28, 00, 00, 00 };
static const u8 mts_read_image_sig_len = 4;
static const unsigned char mts_direction[256/8] = {
	0x28, 0x81, 0x14, 0x14, 0x20, 0x01, 0x90, 0x77,
	0x0C, 0x20, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};


#define MTS_DIRECTION_IS_IN(x) ((mts_direction[x>>3] >> (x & 7)) & 1)

static void
mts_build_transfer_context( Scsi_Cmnd *srb, struct mts_desc* desc )
{
	int pipe;
	struct scatterlist * sg;
	
	MTS_DEBUG_GOT_HERE();

	desc->context.instance = desc;
	desc->context.srb = srb;
	desc->context.fragment = 0;

	if (!srb->use_sg) {
		if ( !srb->bufflen ){
			desc->context.data = 0;
			desc->context.data_length = 0;
			return;
		} else {
			desc->context.data = srb->buffer;
			desc->context.data_length = srb->bufflen;
			MTS_DEBUG("length = %d or %d\n",
				  srb->request_bufflen, srb->bufflen);
		}
	} else {
		MTS_DEBUG("Using scatter/gather\n");
		sg = srb->buffer;
		desc->context.data = page_address(sg[0].page) + sg[0].offset;
		desc->context.data_length = sg[0].length;
	}


	/* can't rely on srb->sc_data_direction */

	/* Brutally ripped from usb-storage */

	if ( !memcmp( srb->cmnd, mts_read_image_sig, mts_read_image_sig_len )
) { 		pipe = usb_rcvbulkpipe(desc->usb_dev,desc->ep_image);
		MTS_DEBUG( "transfering from desc->ep_image == %d\n",
			   (int)desc->ep_image );
	} else if ( MTS_DIRECTION_IS_IN(srb->cmnd[0]) ) {
			pipe = usb_rcvbulkpipe(desc->usb_dev,desc->ep_response);
			MTS_DEBUG( "transfering from desc->ep_response == %d\n",
				   (int)desc->ep_response);
	} else {
		MTS_DEBUG("transfering to desc->ep_out == %d\n",
			  (int)desc->ep_out);
		pipe = usb_sndbulkpipe(desc->usb_dev,desc->ep_out);
	}
	desc->context.data_pipe = pipe;
}


static
int mts_scsi_queuecommand( Scsi_Cmnd *srb, mts_scsi_cmnd_callback callback )
{
	struct mts_desc* desc = (struct mts_desc*)(srb->host->hostdata[0]);
	int err = 0;
	int res;

	MTS_DEBUG_GOT_HERE();
	mts_show_command(srb);
	mts_debug_dump(desc);

	if ( srb->device->lun || srb->device->id || srb->device->channel ) {

		MTS_DEBUG("Command to LUN=%d ID=%d CHANNEL=%d from SCSI layer\n",(int)srb->device->lun,(int)srb->device->id, (int)srb->device->channel );

		MTS_DEBUG("this device doesn't exist\n");

		srb->result = DID_BAD_TARGET << 16;

		if(likely(callback != NULL))
			callback(srb);

		goto out;
	}

	
	FILL_BULK_URB(desc->urb,
		      desc->usb_dev,
		      usb_sndbulkpipe(desc->usb_dev,desc->ep_out),
		      srb->cmnd,
		      srb->cmd_len,
		      mts_command_done,
		      &desc->context
		      );


	mts_build_transfer_context( srb, desc );
	desc->context.final_callback = callback;
	
	/* here we need ATOMIC as we are called with the iolock */
	res=usb_submit_urb(desc->urb, GFP_ATOMIC);

	if(unlikely(res)){
		MTS_ERROR("error %d submitting URB\n",(int)res);
		srb->result = DID_ERROR << 16;

		if(likely(callback != NULL))
			callback(srb);

	}

out:
	return err;
}
/*
 * this defines our 'host'
 */

/* NOTE: This is taken from usb-storage, should be right. */


static Scsi_Host_Template mts_scsi_host_template = {
	name:           "microtekX6",
	detect:		mts_scsi_detect,
	release:	mts_scsi_release,
	queuecommand:	mts_scsi_queuecommand,

	eh_abort_handler:	mts_scsi_abort,
	eh_host_reset_handler:	mts_scsi_host_reset,

	sg_tablesize:		SG_ALL,
	can_queue:		1,
	this_id:		-1,
	cmd_per_lun:		1,
	present:		0,
	unchecked_isa_dma:	FALSE,
	use_clustering:		TRUE,
	emulated:		TRUE
};


/* USB layer driver interface implementation */

static void mts_usb_disconnect (struct usb_device *dev, void *ptr)
{
	struct mts_desc* to_remove = (struct mts_desc*)ptr;

	MTS_DEBUG_GOT_HERE();

	/* leave the list - lock it */
	down(&mts_list_semaphore);

	mts_remove_nolock(to_remove);

	up(&mts_list_semaphore);
}

struct vendor_product
{
	char* name;
	enum
	{
		mts_sup_unknown=0,
		mts_sup_alpha,
		mts_sup_full
	}
	support_status;
} ;


/* These are taken from the msmUSB.inf file on the Windows driver CD */
const static struct vendor_product mts_supported_products[] =
{
	{ "Phantom 336CX",	mts_sup_unknown},
	{ "Phantom 336CX",	mts_sup_unknown},
	{ "Scanmaker X6",	mts_sup_alpha},
	{ "Phantom C6",		mts_sup_unknown},
	{ "Phantom 336CX",	mts_sup_unknown},
	{ "ScanMaker V6USL",	mts_sup_unknown},
	{ "ScanMaker V6USL",	mts_sup_unknown},
	{ "Scanmaker V6UL",	mts_sup_unknown},
	{ "Scanmaker V6UPL",	mts_sup_alpha},
};

/* The entries of microtek_table must correspond, line-by-line to
   the entries of mts_supported_products[]. */

static struct usb_device_id mts_usb_ids [] =
{
	{ USB_DEVICE(0x4ce, 0x0300) },
	{ USB_DEVICE(0x5da, 0x0094) },
	{ USB_DEVICE(0x5da, 0x0099) },
	{ USB_DEVICE(0x5da, 0x009a) },
	{ USB_DEVICE(0x5da, 0x00a0) },
	{ USB_DEVICE(0x5da, 0x00a3) },
	{ USB_DEVICE(0x5da, 0x80a3) },
	{ USB_DEVICE(0x5da, 0x80ac) },
	{ USB_DEVICE(0x5da, 0x00b6) },
	{ }						/* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, mts_usb_ids);


static void * mts_usb_probe (struct usb_device *dev, unsigned int interface,
			     const struct usb_device_id *id)
{
	int i;
	int result;
	int ep_out = -1;
	int ep_in_set[3]; /* this will break if we have more than three endpoints
			   which is why we check */
	int *ep_in_current = ep_in_set;

	struct mts_desc * new_desc;
	struct vendor_product const* p;

	/* the altsettting 0 on the interface we're probing */
	struct usb_interface_descriptor *altsetting;

	MTS_DEBUG_GOT_HERE();
	MTS_DEBUG( "usb-device descriptor at %x\n", (int)dev );

	MTS_DEBUG( "product id = 0x%x, vendor id = 0x%x\n",
		   (int)dev->descriptor.idProduct,
		   (int)dev->descriptor.idVendor );

	MTS_DEBUG_GOT_HERE();

	p = &mts_supported_products[id - mts_usb_ids];

	MTS_DEBUG_GOT_HERE();

	MTS_DEBUG( "found model %s\n", p->name );
	if ( p->support_status != mts_sup_full )
		MTS_MESSAGE( "model %s is not known to be fully supported, reports welcome!\n",
			     p->name );

	/* the altsettting 0 on the interface we're probing */
	altsetting =
		&(dev->actconfig->interface[interface].altsetting[0]);


	/* Check if the config is sane */

	if ( altsetting->bNumEndpoints != MTS_EP_TOTAL ) {
		MTS_WARNING( "expecting %d got %d endpoints! Bailing out.\n",
			     (int)MTS_EP_TOTAL, (int)altsetting->bNumEndpoints );
		return NULL;
	}

	for( i = 0; i < altsetting->bNumEndpoints; i++ ) {
		if ((altsetting->endpoint[i].bmAttributes &
		     USB_ENDPOINT_XFERTYPE_MASK) != USB_ENDPOINT_XFER_BULK) {

			MTS_WARNING( "can only deal with bulk endpoints; endpoint %d is not bulk.\n",
			     (int)altsetting->endpoint[i].bEndpointAddress );
		} else {
			if (altsetting->endpoint[i].bEndpointAddress &
			    USB_DIR_IN)
				*ep_in_current++
					= altsetting->endpoint[i].bEndpointAddress &
					USB_ENDPOINT_NUMBER_MASK;
			else {
				if ( ep_out != -1 ) {
					MTS_WARNING( "can only deal with one output endpoints. Bailing out." );
					return NULL;
				}

				ep_out = altsetting->endpoint[i].bEndpointAddress &
					USB_ENDPOINT_NUMBER_MASK;
			}
		}

	}


	if ( ep_out == -1 ) {
		MTS_WARNING( "couldn't find an output bulk endpoint. Bailing out.\n" );
		return NULL;
	}


	/* I don't understand the following fully (it's from usb-storage) -- John */

	/* set the interface -- STALL is an acceptable response here */
	result = usb_set_interface(dev, altsetting->bInterfaceNumber, 0);

	MTS_DEBUG("usb_set_interface returned %d.\n",result);
	switch( result )
	{
	case 0: /* no error */
		break;
		
	case -EPIPE:
		usb_clear_halt(dev, usb_sndctrlpipe(dev, 0));
		MTS_DEBUG( "clearing clearing stall on control interface\n" );
		break;
		
	default:
		MTS_DEBUG( "unknown error %d from usb_set_interface\n",
			(int)result );
 		return NULL;
	}
	
	
	/* allocating a new descriptor */
	new_desc = (struct mts_desc *)kmalloc(sizeof(struct mts_desc), GFP_KERNEL);
	if (new_desc == NULL)
	{
		MTS_ERROR("couldn't allocate scanner desc, bailing out!\n");
		return NULL;
	}

	memset( new_desc, 0, sizeof(*new_desc) );
	new_desc->urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!new_desc->urb) {
		kfree(new_desc);
		return NULL;
	}
		
	/* initialising that descriptor */
	new_desc->usb_dev = dev;
	new_desc->interface = interface;

	init_MUTEX(&new_desc->lock);

	if(mts_list){
		new_desc->host_number = mts_list->host_number+1;
	} else {
		new_desc->host_number = 0;
	}
	
	/* endpoints */
	
	new_desc->ep_out = ep_out;
	new_desc->ep_response = ep_in_set[0];
	new_desc->ep_image = ep_in_set[1];


	if ( new_desc->ep_out != MTS_EP_OUT )
		MTS_WARNING( "will this work? Command EP is not usually %d\n",
			     (int)new_desc->ep_out );

	if ( new_desc->ep_response != MTS_EP_RESPONSE )
		MTS_WARNING( "will this work? Response EP is not usually %d\n",
			     (int)new_desc->ep_response );

	if ( new_desc->ep_image != MTS_EP_IMAGE )
		MTS_WARNING( "will this work? Image data EP is not usually %d\n",
			     (int)new_desc->ep_image );


	/* Initialize the host template based on the default one */
	memcpy(&(new_desc->ctempl), &mts_scsi_host_template, sizeof(mts_scsi_host_template));
	/* HACK from usb-storage - this is needed for scsi detection */
	(struct mts_desc *)new_desc->ctempl.proc_dir = new_desc; /* FIXME */

	MTS_DEBUG("registering SCSI module\n");

	new_desc->ctempl.module = THIS_MODULE;
	result = scsi_register_host(&new_desc->ctempl);
	/* Will get hit back in microtek_detect by this func */
	if ( result )
	{
		MTS_ERROR( "error %d from scsi_register_host! Help!\n",
			   (int)result );

		/* FIXME: need more cleanup? */
		kfree( new_desc );
		return NULL;
	}
	MTS_DEBUG_GOT_HERE();

	/* FIXME: the bomb is armed, must the host be registered under lock ? */
	/* join the list - lock it */
	down(&mts_list_semaphore);

	mts_add_nolock( new_desc );

	up(&mts_list_semaphore);


	MTS_DEBUG("completed probe and exiting happily\n");

	return (void *)new_desc;
}



/* get us noticed by the rest of the kernel */

int __init microtek_drv_init(void)
{
	int result;

	MTS_DEBUG_GOT_HERE();
	init_MUTEX(&mts_list_semaphore);

	if ((result = usb_register(&mts_usb_driver)) < 0) {
		MTS_DEBUG("usb_register returned %d\n", result );
		return -1;
	} else {
		MTS_DEBUG("driver registered.\n");
	}

	info(DRIVER_VERSION ":" DRIVER_DESC);

	return 0;
}

void __exit microtek_drv_exit(void)
{
	struct mts_desc* next;

	MTS_DEBUG_GOT_HERE();

	usb_deregister(&mts_usb_driver);

	down(&mts_list_semaphore);

	while (mts_list) {
		/* keep track of where the next one is */
		next = mts_list->next;

		mts_remove_nolock( mts_list );

		/* advance the list pointer */
		mts_list = next;
	}

	up(&mts_list_semaphore);
}

module_init(microtek_drv_init);
module_exit(microtek_drv_exit);

MODULE_AUTHOR( DRIVER_AUTHOR );
MODULE_DESCRIPTION( DRIVER_DESC );
MODULE_LICENSE("GPL");