/* Driver for Microtek Scanmaker X6 USB scanner, and possibly others.
 *
 * (C) Copyright 2000 John Fremlin <vii@penguinpowered.com>
 * (C) Copyright 2000 Oliver Neukum <Oliver.Neukum@lrz.uni-muenchen.de>
 *
 * Parts shamelessly stolen from usb-storage and copyright by their
 * authors. Thanks to Matt Dharm for giving us permission!
 *
 * This driver implements a SCSI host controller driver and a USB
 * device driver. To avoid confusion, all the USB related stuff is
 * prefixed by mts_usb_ and all the SCSI stuff by mts_scsi_.
 *
 * Microtek (www.microtek.com) did not release the specifications for
 * their USB protocol to us, so we had to reverse engineer them. We
 * don't know for which models they are valid.
 *
 * The X6 USB has three bulk endpoints, one output (0x1) down which
 * commands and outgoing data are sent, and two input: 0x82 from which
 * normal data is read from the scanner (in packets of maximum 32
 * bytes) and from which the status byte is read, and 0x83 from which
 * the results of a scan (or preview) are read in up to 64 * 1024 byte
 * chunks by the Windows driver. We don't know how much it is possible
 * to read at a time from 0x83.
 *
 * It seems possible to read (with URB transfers) everything from 0x82
 * in one go, without bothering to read in 32 byte chunks.
 *
 * There seems to be an optimisation of a further READ implicit if
 * you simply read from 0x83.
 *
 * Guessed protocol:
 *
 *	Send raw SCSI command to EP 0x1
 *
 *	If there is data to receive:
 *		If the command was READ datatype=image:
 *			Read a lot of data from EP 0x83
 *		Else:
 *			Read data from EP 0x82
 *	Else:
 *		If there is data to transmit:
 *			Write it to EP 0x1
 *
 *	Read status byte from EP 0x82
 *
 * References:
 *
 * The SCSI command set for the scanner is available from
 *	ftp://ftp.microtek.com/microtek/devpack/
 *
 * Microtek NV sent us a more up to date version of the document. If
 * you want it, just send mail.
 *
 * Status:
 *
 *	Untested with multiple scanners.
 *	Untested on SMP.
 *	Untested on a bigendian machine.
 *
 * History:
 *
 *	20000417 starting history
 *	20000417 fixed load oops
 *	20000417 fixed unload oops
 *	20000419 fixed READ IMAGE detection
 *	20000424 started conversion to use URBs
 *	20000502 handled short transfers as errors
 *	20000513 rename and organisation of functions (john)
 *	20000513 added IDs for all products supported by Windows driver (john)
 *	20000514 Rewrote mts_scsi_queuecommand to use URBs (john)
 *	20000514 Version 0.0.8j
 *      20000514 Fix reporting of non-existant devices to SCSI layer (john)
 *	20000514 Added MTS_DEBUG_INT (john)
 *	20000514 Changed "usb-microtek" to "microtek" for consistency (john)
 *	20000514 Stupid bug fixes (john)
 *	20000514 Version 0.0.9j
 *	20000515 Put transfer context and URB in mts_desc (john)
 *	20000515 Added prelim turn off debugging support (john)
 *	20000515 Version 0.0.10j
 *      20000515 Fixed up URB allocation (clear URB on alloc) (john)
 *      20000515 Version 0.0.11j
 *	20000516 Removed unnecessary spinlock in mts_transfer_context (john)
 *	20000516 Removed unnecessary up on instance lock in mts_remove_nolock (john)
 *	20000516 Implemented (badly) scsi_abort (john)
 *	20000516 Version 0.0.12j
 *      20000517 Hopefully removed mts_remove_nolock quasideadlock (john)
 *      20000517 Added mts_debug_dump to print ll USB info (john)
 *	20000518 Tweaks and documentation updates (john)
 *	20000518 Version 0.0.13j
 *	20000518 Cleaned up abort handling (john)
 *	20000523 Removed scsi_command and various scsi_..._resets (john)
 *	20000523 Added unlink URB on scsi_abort, now OHCI supports it (john)
 *	20000523 Fixed last tiresome compile warning (john)
 *	20000523 Version 0.0.14j (though version 0.1 has come out?)
 *	20000602 Added primitive reset
 *	20000602 Version 0.2.0
 *	20000603 various cosmetic changes
 *	20000603 Version 0.2.1
 *	20000620 minor cosmetic changes
 *	20000620 Version 0.2.2
 *	20000822 Hopefully fixed deadlock in mts_remove_nolock()
 *	20000822 Fixed minor race in mts_transfer_cleanup()
 *	20000822 Fixed deadlock on submission error in queuecommand
 *	20000822 Version 0.2.3
 *	20000913 Reduced module size if debugging is off
 *	20000913 Version 0.2.4
 *      20010210 New abort logic
 *      20010210 Version 0.3.0
 *	20010217 Merged scatter/gather
 *	20010218 Version 0.4.0
 *	20010218 Cosmetic fixes
 *	20010218 Version 0.4.1
 *      20010306 Abort while using scatter/gather
 *      20010306 Version 0.4.2
 *      20010311 Remove all timeouts and tidy up generally (john)
 *	20010320 check return value of scsi_register()
 *	20010320 Version 0.4.3
 *	20010408 Identify version on module load.
 *	20011003 Fix multiple requests
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/smp_lock.h>
#include <linux/usb.h>
#include <linux/proc_fs.h>

#include <asm/atomic.h>
#include <linux/blk.h>
#include "../../scsi/scsi.h"
#include "../../scsi/hosts.h"
#include "../../scsi/sd.h"

#include "microtek.h"

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.4.3"
#define DRIVER_AUTHOR "John Fremlin <vii@penguinpowered.com>, Oliver Neukum <Oliver.Neukum@lrz.uni-muenchen.de>"
#define DRIVER_DESC "Microtek Scanmaker X6 USB scanner driver"

/* Should we do debugging? */

//#define MTS_DO_DEBUG

/* USB layer driver interface */

static void *mts_usb_probe(struct usb_device *dev, unsigned int interface,
			 const struct usb_device_id *id);
static void mts_usb_disconnect(struct usb_device *dev, void *ptr);

static struct usb_device_id mts_usb_ids [];

static struct usb_driver mts_usb_driver = {
	name:		"microtekX6",
	probe:		mts_usb_probe,
	disconnect:	mts_usb_disconnect,
	id_table:	mts_usb_ids,
};


/* Internal driver stuff */

#define MTS_VERSION	"0.4.3"
#define MTS_NAME	"microtek usb (rev " MTS_VERSION "): "

#define MTS_WARNING(x...) \
	printk( KERN_WARNING MTS_NAME x )
#define MTS_ERROR(x...) \
	printk( KERN_ERR MTS_NAME x )
#define MTS_INT_ERROR(x...) \
	MTS_ERROR(x)
#define MTS_MESSAGE(x...) \
	printk( KERN_INFO MTS_NAME x )

#if defined MTS_DO_DEBUG

#define MTS_DEBUG(x...) \
	printk( KERN_DEBUG MTS_NAME x )

#define MTS_DEBUG_GOT_HERE() \
	MTS_DEBUG("got to %s:%d (%s)\n", __FILE__, (int)__LINE__, __PRETTY_FUNCTION__ )
#define MTS_DEBUG_INT() \
	do { MTS_DEBUG_GOT_HERE(); \
	     MTS_DEBUG("transfer = 0x%x context = 0x%x\n",(int)transfer,(int)context ); \
	     MTS_DEBUG("status = 0x%x data-length = 0x%x sent = 0x%x\n",(int)transfer->status,(int)context->data_length, (int)transfer->actual_length ); \
             mts_debug_dump(context->instance);\
	   } while(0)
#else

#define MTS_NUL_STATEMENT do { } while(0)

#define MTS_DEBUG(x...)	MTS_NUL_STATEMENT
#define MTS_DEBUG_GOT_HERE() MTS_NUL_STATEMENT
#define MTS_DEBUG_INT() MTS_NUL_STATEMENT

#endif



#define MTS_INT_INIT()\
	struct mts_transfer_context* context = (struct mts_transfer_context*)transfer->context; \
	MTS_DEBUG_INT();\

#ifdef MTS_DO_DEBUG

static inline void mts_debug_dump(struct mts_desc* desc) {
	MTS_DEBUG("desc at 0x%x: halted = %02x%02x, toggle = %02x%02x\n",
		  (int)desc,(int)desc->usb_dev->halted[1],(int)desc->usb_dev->halted[0],
		  (int)desc->usb_dev->toggle[1],(int)desc->usb_dev->toggle[0]
		);
	MTS_DEBUG("ep_out=%x ep_response=%x ep_image=%x\n",
		  usb_sndbulkpipe(desc->usb_dev,desc->ep_out),
		  usb_rcvbulkpipe(desc->usb_dev,desc->ep_response),
		  usb_rcvbulkpipe(desc->usb_dev,desc->ep_image)
		);
}


static inline void mts_show_command(Scsi_Cmnd *srb)
{
	char *what = NULL;

	switch (srb->cmnd[0]) {
	case TEST_UNIT_READY: what = "TEST_UNIT_READY"; break;
	case REZERO_UNIT: what = "REZERO_UNIT"; break;
	case REQUEST_SENSE: what = "REQUEST_SENSE"; break;
	case FORMAT_UNIT: what = "FORMAT_UNIT"; break;
	case READ_BLOCK_LIMITS: what = "READ_BLOCK_LIMITS"; break;
	case REASSIGN_BLOCKS: what = "REASSIGN_BLOCKS"; break;
	case READ_6: what = "READ_6"; break;
	case WRITE_6: what = "WRITE_6"; break;
	case SEEK_6: what = "SEEK_6"; break;
	case READ_REVERSE: what = "READ_REVERSE"; break;
	case WRITE_FILEMARKS: what = "WRITE_FILEMARKS"; break;
	case SPACE: what = "SPACE"; break;
	case INQUIRY: what = "INQUIRY"; break;
	case RECOVER_BUFFERED_DATA: what = "RECOVER_BUFFERED_DATA"; break;
	case MODE_SELECT: what = "MODE_SELECT"; break;
	case RESERVE: what = "RESERVE"; break;
	case RELEASE: what = "RELEASE"; break;
	case COPY: what = "COPY"; break;
	case ERASE: what = "ERASE"; break;
	case MODE_SENSE: what = "MODE_SENSE"; break;
	case START_STOP: what = "START_STOP"; break;
	case RECEIVE_DIAGNOSTIC: what = "RECEIVE_DIAGNOSTIC"; break;
	case SEND_DIAGNOSTIC: what = "SEND_DIAGNOSTIC"; break;
	case ALLOW_MEDIUM_REMOVAL: what = "ALLOW_MEDIUM_REMOVAL"; break;
	case SET_WINDOW: what = "SET_WINDOW"; break;
	case READ_CAPACITY: what = "READ_CAPACITY"; break;
	case READ_10: what = "READ_10"; break;
	case WRITE_10: what = "WRITE_10"; break;
	case SEEK_10: what = "SEEK_10"; break;
	case WRITE_VERIFY: what = "WRITE_VERIFY"; break;
	case VERIFY: what = "VERIFY"; break;
	case SEARCH_HIGH: what = "SEARCH_HIGH"; break;
	case SEARCH_EQUAL: what = "SEARCH_EQUAL"; break;
	case SEARCH_LOW: what = "SEARCH_LOW"; break;
	case SET_LIMITS: what = "SET_LIMITS"; break;
	case READ_POSITION: what = "READ_POSITION"; break;
	case SYNCHRONIZE_CACHE: what = "SYNCHRONIZE_CACHE"; break;
	case LOCK_UNLOCK_CACHE: what = "LOCK_UNLOCK_CACHE"; break;
	case READ_DEFECT_DATA: what = "READ_DEFECT_DATA"; break;
	case MEDIUM_SCAN: what = "MEDIUM_SCAN"; break;
	case COMPARE: what = "COMPARE"; break;
	case COPY_VERIFY: what = "COPY_VERIFY"; break;
	case WRITE_BUFFER: what = "WRITE_BUFFER"; break;
	case READ_BUFFER: what = "READ_BUFFER"; break;
	case UPDATE_BLOCK: what = "UPDATE_BLOCK"; break;
	case READ_LONG: what = "READ_LONG"; break;
	case WRITE_LONG: what = "WRITE_LONG"; break;
	case CHANGE_DEFINITION: what = "CHANGE_DEFINITION"; break;
	case WRITE_SAME: what = "WRITE_SAME"; break;
	case READ_TOC: what = "READ_TOC"; break;
	case LOG_SELECT: what = "LOG_SELECT"; break;
	case LOG_SENSE: what = "LOG_SENSE"; break;
	case MODE_SELECT_10: what = "MODE_SELECT_10"; break;
	case MODE_SENSE_10: what = "MODE_SENSE_10"; break;
	case MOVE_MEDIUM: what = "MOVE_MEDIUM"; break;
	case READ_12: what = "READ_12"; break;
	case WRITE_12: what = "WRITE_12"; break;
	case WRITE_VERIFY_12: what = "WRITE_VERIFY_12"; break;
	case SEARCH_HIGH_12: what = "SEARCH_HIGH_12"; break;
	case SEARCH_EQUAL_12: what = "SEARCH_EQUAL_12"; break;
	case SEARCH_LOW_12: what = "SEARCH_LOW_12"; break;
	case READ_ELEMENT_STATUS: what = "READ_ELEMENT_STATUS"; break;
	case SEND_VOLUME_TAG: what = "SEND_VOLUME_TAG"; break;
	case WRITE_LONG_2: what = "WRITE_LONG_2"; break;
	default:
		MTS_DEBUG("can't decode command\n");
		goto out;
		break;
	}
	MTS_DEBUG( "Command %s (%d bytes)\n", what, srb->cmd_len);

 out:
	MTS_DEBUG( "  %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x\n",
	       srb->cmnd[0], srb->cmnd[1], srb->cmnd[2], srb->cmnd[3], srb->cmnd[4], srb->cmnd[5],
	       srb->cmnd[6], srb->cmnd[7], srb->cmnd[8], srb->cmnd[9]);
}

#else

static inline void mts_show_command(Scsi_Cmnd * dummy)
{
}

static inline void mts_debug_dump(struct mts_desc* dummy)
{
}

#endif

static inline void mts_urb_abort(struct mts_desc* desc) {
	MTS_DEBUG_GOT_HERE();
	mts_debug_dump(desc);

	usb_unlink_urb( desc->urb );
}

static struct mts_desc * mts_list; /* list of active scanners */
struct semaphore mts_list_semaphore;

/* Internal list operations */

static
void mts_remove_nolock( struct mts_desc* to_remove )
{
	MTS_DEBUG( "removing 0x%x from list\n",
		   (int)to_remove );

	lock_kernel();
	mts_urb_abort(to_remove);

	MTS_DEBUG_GOT_HERE();

	if ( to_remove != mts_list ) {
		MTS_DEBUG_GOT_HERE();
		if (to_remove->prev && to_remove->next)
			to_remove->prev->next = to_remove->next;
	} else {
		MTS_DEBUG_GOT_HERE();
		mts_list = to_remove->next;
		if (mts_list) {
			MTS_DEBUG_GOT_HERE();
			mts_list->prev = 0;
		}
	}

	if ( to_remove->next ) {
		MTS_DEBUG_GOT_HERE();
		to_remove->next->prev = to_remove->prev;
	}

	MTS_DEBUG_GOT_HERE();
	scsi_unregister_host(&to_remove->ctempl);
	unlock_kernel();

	usb_free_urb(to_remove->urb);
	kfree( to_remove );
}

static
void mts_add_nolock( struct mts_desc* to_add )
{
	MTS_DEBUG( "adding 0x%x to list\n", (int)to_add );

	to_add->prev = 0;
	to_add->next = mts_list;
	if ( mts_list ) {
		mts_list->prev = to_add;
	}

	mts_list = to_add;
}




/* SCSI driver interface */

/* scsi related functions - dummies for now mostly */

static int mts_scsi_release(struct Scsi_Host *psh)
{
	MTS_DEBUG_GOT_HERE();

	return 0;
}

static int mts_scsi_abort (Scsi_Cmnd *srb)
{
	struct mts_desc* desc = (struct mts_desc*)(srb->host->hostdata[0]);

	MTS_DEBUG_GOT_HERE();

	mts_urb_abort(desc);

	return SCSI_ABORT_PENDING;
}

static int mts_scsi_host_reset (Scsi_Cmnd *srb)
{
	struct mts_desc* desc = (struct mts_desc*)(srb->host->hostdata[0]);

	MTS_DEBUG_GOT_HERE();
	mts_debug_dump(desc);

	usb_reset_device(desc->usb_dev); /*FIXME: untested on new reset code */
	return 0;  /* RANT why here 0 and not SUCCESS */
}

/* the core of the scsi part */

/* faking a detection - which can't fail :-) */

static int mts_scsi_detect (struct SHT * sht)
{
	/* Whole function stolen from usb-storage */

	struct mts_desc * desc = (struct mts_desc *)sht->proc_dir;
	/* What a hideous hack! */

	char local_name[48];

	MTS_DEBUG_GOT_HERE();

	/* set up the name of our subdirectory under /proc/scsi/ */
	sprintf(local_name, "microtek-%d", desc->host_number);
	sht->proc_name = kmalloc (strlen(local_name) + 1, GFP_KERNEL);
	/* FIXME: where is this freed ? */

	if (!sht->proc_name) {
		MTS_ERROR( "unable to allocate memory for proc interface!!\n" );
		return 0;
	}

	strcpy(sht->proc_name, local_name);

 	sht->proc_dir = NULL;

	/* In host->hostdata we store a pointer to desc */
	desc->host = scsi_register(sht, sizeof(desc));
	if (desc->host == NULL) {
		MTS_ERROR("Cannot register due to low memory");
		kfree(sht->proc_name);
		return 0;
	}
	desc->host->hostdata[0] = (unsigned long)desc;
/* FIXME: what if sizeof(void*) != sizeof(unsigned long)? */

	return 1;
}



/* Main entrypoint: SCSI commands are dispatched to here */



static
int mts_scsi_queuecommand (Scsi_Cmnd *srb, mts_scsi_cmnd_callback callback );

static void mts_transfer_cleanup( struct urb *transfer );
static void mts_do_sg(struct urb * transfer);


inline static
void mts_int_submit_urb (struct urb* transfer,
			int pipe,
			void* data,
			unsigned length,
			mts_usb_urb_callback callback )
/* Interrupt context! */

/* Holding transfer->context->lock! */
{
	int res;

	MTS_INT_INIT();

	FILL_BULK_URB(transfer,
		      context->instance->usb_dev,
		      pipe,
		      data,
		      length,
		      callback,
		      context
		);

	transfer->status = 0;

	res = usb_submit_urb( transfer, GFP_ATOMIC );
	if ( unlikely(res) ) {
		MTS_INT_ERROR( "could not submit URB! Error was %d\n",(int)res );
		context->srb->result = DID_ERROR << 16;
		mts_transfer_cleanup(transfer);
	}
	return;
}


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

	if ( likely(context->final_callback != NULL) )
		context->final_callback(context->srb);

}

static void mts_transfer_done( struct urb *transfer )
{
	MTS_INT_INIT();

	context->srb->result &= MTS_SCSI_ERR_MASK;
	context->srb->result |= (unsigned)context->status<<1;

	mts_transfer_cleanup(transfer);

	return;
}


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");