ataflop.c

讲述linux的初始化过程

		return;
	}
	/* not yet off, try again */

  retry:
	/* Test again later; if tested too often, it seems there is no disk
	 * in the drive and the FDC will leave the motor on forever (or,
	 * at least until a disk is inserted). So we'll test only twice
	 * per second from then on...
	 */
	mod_timer(&motor_off_timer,
		  jiffies + (MotorOffTrys++ < FD_MOTOR_OFF_MAXTRY ? HZ/20 : HZ/2));
}


/* This function is repeatedly called to detect disk changes (as good
 * as possible) and keep track of the current state of the write protection.
 */

static void check_change( void )
{
	static int    drive = 0;

	unsigned long flags;
	unsigned char old_porta;
	int			  stat;

	if (++drive > 1 || !UD.connected)
		drive = 0;

	save_flags(flags);
	cli(); /* protect against various other ints mucking around with the PSG */

	if (!stdma_islocked()) {
		sound_ym.rd_data_reg_sel = 14;
		old_porta = sound_ym.rd_data_reg_sel;
		sound_ym.wd_data = (old_porta | DSKDRVNONE) &
			               ~(drive == 0 ? DSKDRV0 : DSKDRV1);
		stat = !!(FDC_READ( FDCREG_STATUS ) & FDCSTAT_WPROT);
		sound_ym.wd_data = old_porta;

		if (stat != UD.wpstat) {
			DPRINT(( "wpstat[%d] = %d\n", drive, stat ));
			UD.wpstat = stat;
			set_bit (drive, &changed_floppies);
		}
	}
	restore_flags(flags);

	start_check_change_timer();
}

 
/* Handling of the Head Settling Flag: This flag should be set after each
 * seek operation, because we don't use seeks with verify.
 */

static __inline__ void set_head_settle_flag( void )
{
	HeadSettleFlag = FDCCMDADD_E;
}

static __inline__ int get_head_settle_flag( void )
{
	int	tmp = HeadSettleFlag;
	HeadSettleFlag = 0;
	return( tmp );
}

  
  

/* General Interrupt Handling */

static void (*FloppyIRQHandler)( int status ) = NULL;

static void floppy_irq (int irq, void *dummy, struct pt_regs *fp)
{
	unsigned char status;
	void (*handler)( int );

	handler = xchg(&FloppyIRQHandler, NULL);

	if (handler) {
		nop();
		status = FDC_READ( FDCREG_STATUS );
		DPRINT(("FDC irq, status = %02x handler = %08lx\n",status,(unsigned long)handler));
		handler( status );
	}
	else {
		DPRINT(("FDC irq, no handler\n"));
	}
}


/* Error handling: If some error happened, retry some times, then
 * recalibrate, then try again, and fail after MAX_ERRORS.
 */

static void fd_error( void )
{
	if (IsFormatting) {
		IsFormatting = 0;
		FormatError = 1;
		wake_up( &format_wait );
		return;
	}
		
	if (QUEUE_EMPTY) return;
	CURRENT->errors++;
	if (CURRENT->errors >= MAX_ERRORS) {
		printk(KERN_ERR "fd%d: too many errors.\n", SelectedDrive );
		end_request( 0 );
	}
	else if (CURRENT->errors == RECALIBRATE_ERRORS) {
		printk(KERN_WARNING "fd%d: recalibrating\n", SelectedDrive );
		if (SelectedDrive != -1)
			SUD.track = -1;
	}
	redo_fd_request();
}



#define	SET_IRQ_HANDLER(proc) do { FloppyIRQHandler = (proc); } while(0)


/* ---------- Formatting ---------- */

#define FILL(n,val)		\
    do {			\
	memset( p, val, n );	\
	p += n;			\
    } while(0)

static int do_format(kdev_t device, struct atari_format_descr *desc)
{
	unsigned char	*p;
	int sect, nsect;
	unsigned long	flags;
	int type, drive = MINOR(device) & 3;

	DPRINT(("do_format( dr=%d tr=%d he=%d offs=%d )\n",
		drive, desc->track, desc->head, desc->sect_offset ));

	save_flags(flags);
	cli();
	while( fdc_busy ) sleep_on( &fdc_wait );
	fdc_busy = 1;
	stdma_lock(floppy_irq, NULL);
	atari_turnon_irq( IRQ_MFP_FDC ); /* should be already, just to be sure */
	restore_flags(flags);

	type = MINOR(device) >> 2;
	if (type) {
		if (--type >= NUM_DISK_MINORS ||
		    minor2disktype[type].drive_types > DriveType) {
			redo_fd_request();
			return -EINVAL;
		}
		type = minor2disktype[type].index;
		UDT = &disk_type[type];
	}

	if (!UDT || desc->track >= UDT->blocks/UDT->spt/2 || desc->head >= 2) {
		redo_fd_request();
		return -EINVAL;
	}

	nsect = UDT->spt;
	p = TrackBuffer;
	/* The track buffer is used for the raw track data, so its
	   contents become invalid! */
	BufferDrive = -1;
	/* stop deselect timer */
	del_timer( &motor_off_timer );

	FILL( 60 * (nsect / 9), 0x4e );
	for( sect = 0; sect < nsect; ++sect ) {
		FILL( 12, 0 );
		FILL( 3, 0xf5 );
		*p++ = 0xfe;
		*p++ = desc->track;
		*p++ = desc->head;
		*p++ = (nsect + sect - desc->sect_offset) % nsect + 1;
		*p++ = 2;
		*p++ = 0xf7;
		FILL( 22, 0x4e );
		FILL( 12, 0 );
		FILL( 3, 0xf5 );
		*p++ = 0xfb;
		FILL( 512, 0xe5 );
		*p++ = 0xf7;
		FILL( 40, 0x4e );
	}
	FILL( TrackBuffer+BUFFER_SIZE-p, 0x4e );

	IsFormatting = 1;
	FormatError = 0;
	ReqTrack = desc->track;
	ReqSide  = desc->head;
	do_fd_action( drive );

	sleep_on( &format_wait );

	redo_fd_request();
	return( FormatError ? -EIO : 0 );	
}


/* do_fd_action() is the general procedure for a fd request: All
 * required parameter settings (drive select, side select, track
 * position) are checked and set if needed. For each of these
 * parameters and the actual reading or writing exist two functions:
 * one that starts the setting (or skips it if possible) and one
 * callback for the "done" interrupt. Each done func calls the next
 * set function to propagate the request down to fd_rwsec_done().
 */

static void do_fd_action( int drive )
{
	DPRINT(("do_fd_action\n"));
	
	if (UseTrackbuffer && !IsFormatting) {
	repeat:
	    if (IS_BUFFERED( drive, ReqSide, ReqTrack )) {
		if (ReqCmd == READ) {
		    copy_buffer( SECTOR_BUFFER(ReqSector), ReqData );
		    if (++ReqCnt < CURRENT->current_nr_sectors) {
			/* read next sector */
			setup_req_params( drive );
			goto repeat;
		    }
		    else {
			/* all sectors finished */
			CURRENT->nr_sectors -= CURRENT->current_nr_sectors;
			CURRENT->sector += CURRENT->current_nr_sectors;
			end_request( 1 );
			redo_fd_request();
			return;
		    }
		}
		else {
		    /* cmd == WRITE, pay attention to track buffer
		     * consistency! */
		    copy_buffer( ReqData, SECTOR_BUFFER(ReqSector) );
		}
	    }
	}

	if (SelectedDrive != drive)
		fd_select_drive( drive );
    
	if (UD.track == -1)
		fd_calibrate();
	else if (UD.track != ReqTrack << UDT->stretch)
		fd_seek();
	else if (IsFormatting)
		fd_writetrack();
	else
		fd_rwsec();
}


/* Seek to track 0 if the current track is unknown */

static void fd_calibrate( void )
{
	if (SUD.track >= 0) {
		fd_calibrate_done( 0 );
		return;
	}

	if (ATARIHW_PRESENT(FDCSPEED))
		dma_wd.fdc_speed = 0; 	/* always seek with 8 Mhz */;
	DPRINT(("fd_calibrate\n"));
	SET_IRQ_HANDLER( fd_calibrate_done );
	/* we can't verify, since the speed may be incorrect */
	FDC_WRITE( FDCREG_CMD, FDCCMD_RESTORE | SUD.steprate );

	NeedSeek = 1;
	MotorOn = 1;
	start_timeout();
	/* wait for IRQ */
}


static void fd_calibrate_done( int status )
{
	DPRINT(("fd_calibrate_done()\n"));
	stop_timeout();
    
	/* set the correct speed now */
	if (ATARIHW_PRESENT(FDCSPEED))
		dma_wd.fdc_speed = SUDT->fdc_speed;
	if (status & FDCSTAT_RECNF) {
		printk(KERN_ERR "fd%d: restore failed\n", SelectedDrive );
		fd_error();
	}
	else {
		SUD.track = 0;
		fd_seek();
	}
}
  
  
/* Seek the drive to the requested track. The drive must have been
 * calibrated at some point before this.
 */
  
static void fd_seek( void )
{
	if (SUD.track == ReqTrack << SUDT->stretch) {
		fd_seek_done( 0 );
		return;
	}

	if (ATARIHW_PRESENT(FDCSPEED)) {
		dma_wd.fdc_speed = 0;	/* always seek witch 8 Mhz */
		MFPDELAY();
	}

	DPRINT(("fd_seek() to track %d\n",ReqTrack));
	FDC_WRITE( FDCREG_DATA, ReqTrack << SUDT->stretch);
	udelay(25);
	SET_IRQ_HANDLER( fd_seek_done );
	FDC_WRITE( FDCREG_CMD, FDCCMD_SEEK | SUD.steprate );

	MotorOn = 1;
	set_head_settle_flag();
	start_timeout();
	/* wait for IRQ */
}


static void fd_seek_done( int status )
{
	DPRINT(("fd_seek_done()\n"));
	stop_timeout();
	
	/* set the correct speed */
	if (ATARIHW_PRESENT(FDCSPEED))
		dma_wd.fdc_speed = SUDT->fdc_speed;
	if (status & FDCSTAT_RECNF) {
		printk(KERN_ERR "fd%d: seek error (to track %d)\n",
				SelectedDrive, ReqTrack );
		/* we don't know exactly which track we are on now! */
		SUD.track = -1;
		fd_error();
	}
	else {
		SUD.track = ReqTrack << SUDT->stretch;
		NeedSeek = 0;
		if (IsFormatting)
			fd_writetrack();
		else
			fd_rwsec();
	}
}


/* This does the actual reading/writing after positioning the head
 * over the correct track.
 */

static int MultReadInProgress = 0;


static void fd_rwsec( void )
{
	unsigned long paddr, flags;
	unsigned int  rwflag, old_motoron;
	unsigned int track;
	
	DPRINT(("fd_rwsec(), Sec=%d, Access=%c\n",ReqSector, ReqCmd == WRITE ? 'w' : 'r' ));
	if (ReqCmd == WRITE) {
		if (ATARIHW_PRESENT(EXTD_DMA)) {
			paddr = virt_to_phys(ReqData);
		}
		else {
			copy_buffer( ReqData, DMABuffer );
			paddr = PhysDMABuffer;
		}
		dma_cache_maintenance( paddr, 512, 1 );
		rwflag = 0x100;
	}
	else {
		if (read_track)
			paddr = PhysTrackBuffer;
		else
			paddr = ATARIHW_PRESENT(EXTD_DMA) ? 
				virt_to_phys(ReqData) : PhysDMABuffer;
		rwflag = 0;
	}

	fd_select_side( ReqSide );
  
	/* Start sector of this operation */
	FDC_WRITE( FDCREG_SECTOR, read_track ? 1 : ReqSector );
	MFPDELAY();
	/* Cheat for track if stretch != 0 */
	if (SUDT->stretch) {
		track = FDC_READ( FDCREG_TRACK);
		MFPDELAY();
		FDC_WRITE( FDCREG_TRACK, track >> SUDT->stretch);
	}
	udelay(25);
  
	/* Setup DMA */
	save_flags(flags);  
	cli();
	dma_wd.dma_lo = (unsigned char)paddr;
	MFPDELAY();
	paddr >>= 8;
	dma_wd.dma_md = (unsigned char)paddr;
	MFPDELAY();
	paddr >>= 8;
	if (ATARIHW_PRESENT(EXTD_DMA))
		st_dma_ext_dmahi = (unsigned short)paddr;
	else
		dma_wd.dma_hi = (unsigned char)paddr;
	MFPDELAY();
	restore_flags(flags);
  
	/* Clear FIFO and switch DMA to correct mode */  
	dma_wd.dma_mode_status = 0x90 | rwflag;  
	MFPDELAY();
	dma_wd.dma_mode_status = 0x90 | (rwflag ^ 0x100);  
	MFPDELAY();
	dma_wd.dma_mode_status = 0x90 | rwflag;
	MFPDELAY();
  
	/* How many sectors for DMA */
	dma_wd.fdc_acces_seccount = read_track ? SUDT->spt : 1;
  
	udelay(25);  
  
	/* Start operation */
	dma_wd.dma_mode_status = FDCSELREG_STP | rwflag;
	udelay(25);
	SET_IRQ_HANDLER( fd_rwsec_done );
	dma_wd.fdc_acces_seccount =
	  (get_head_settle_flag() |
	   (rwflag ? FDCCMD_WRSEC : (FDCCMD_RDSEC | (read_track ? FDCCMDADD_M : 0))));

	old_motoron = MotorOn;
	MotorOn = 1;
	NeedSeek = 1;
	/* wait for interrupt */

	if (read_track) {
		/* If reading a whole track, wait about one disk rotation and
		 * then check if all sectors are read. The FDC will even
		 * search for the first non-existent sector and need 1 sec to
		 * recognise that it isn't present :-(
		 */
		MultReadInProgress = 1;
		mod_timer(&readtrack_timer,
			  /* 1 rot. + 5 rot.s if motor was off  */
			  jiffies + HZ/5 + (old_motoron ? 0 : HZ));
	}
	start_timeout();
}

    
static void fd_readtrack_check( unsigned long dummy )
{
	unsigned long flags, addr, addr2;

	save_flags(flags);  
	cli();

	if (!MultReadInProgress) {
		/* This prevents a race condition that could arise if the
		 * interrupt is triggered while the calling of this timer
		 * callback function takes place. The IRQ function then has
		 * already cleared 'MultReadInProgress'  when flow of control
		 * gets here.
		 */
		restore_flags(flags);
		return;
	}

	/* get the current DMA address */
	/* ++ f.a. read twice to avoid being fooled by switcher */
	addr = 0;
	do {
		addr2 = addr;
		addr = dma_wd.dma_lo & 0xff;
		MFPDELAY();
		addr |= (dma_wd.dma_md & 0xff) << 8;
		MFPDELAY();
		if (ATARIHW_PRESENT( EXTD_DMA ))
			addr |= (st_dma_ext_dmahi & 0xffff) << 16;
		else
			addr |= (dma_wd.dma_hi & 0xff) << 16;
		MFPDELAY();
	} while(addr != addr2);
  
	if (addr >= PhysTrackBuffer + SUDT->spt*512) {
		/* already read enough data, force an FDC interrupt to stop
		 * the read operation
		 */
		SET_IRQ_HANDLER( NULL );
		MultReadInProgress = 0;
		restore_flags(flags);
		DPRINT(("fd_readtrack_check(): done\n"));
		FDC_WRITE( FDCREG_CMD, FDCCMD_FORCI );
		udelay(25);

		/* No error until now -- the FDC would have interrupted
		 * otherwise!
		 */
		fd_rwsec_done1(0);
	}
	else {
		/* not yet finished, wait another tenth rotation */
		restore_flags(flags);
		DPRINT(("fd_readtrack_check(): not yet finished\n"));