/* 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;
}