acsi.c

讲述linux的初始化过程

static int acsicmd_dma( const char *cmd, char *buffer, int blocks, int rwflag, int enable)

{	unsigned long	flags, paddr;
	int				i;

#ifdef NO_WRITE
	if (rwflag || *cmd == 0x0a) {
		printk( "ACSI: Write commands disabled!\n" );
		return( 0 );
	}
#endif
	
	rwflag = rwflag ? 0x100 : 0;
	paddr = virt_to_phys( buffer );

	acsi_delay_end(COMMAND_DELAY);
	DISABLE_IRQ();

	save_flags(flags);  
	cli();
	/* Low on A1 */
	dma_wd.dma_mode_status = 0x88 | rwflag;
	MFPDELAY();

	/* set DMA address */
	dma_wd.dma_lo = (unsigned char)paddr;
	paddr >>= 8;
	MFPDELAY();
	dma_wd.dma_md = (unsigned char)paddr;
	paddr >>= 8;
	MFPDELAY();
	if (ATARIHW_PRESENT(EXTD_DMA))
		st_dma_ext_dmahi = (unsigned short)paddr;
	else
		dma_wd.dma_hi = (unsigned char)paddr;
	MFPDELAY();
	restore_flags(flags);

	/* send the command bytes except the last */
	for( i = 0; i < 5; ++i ) {
		DMA_LONG_WRITE( *cmd++, 0x8a | rwflag );
		udelay(20);
		if (!acsi_wait_for_IRQ( HZ/2 )) return( 0 ); /* timeout */
	}

	/* Clear FIFO and switch DMA to correct direction */  
	dma_wd.dma_mode_status = 0x92 | (rwflag ^ 0x100);  
	MFPDELAY();
	dma_wd.dma_mode_status = 0x92 | rwflag;
	MFPDELAY();

	/* How many sectors for DMA */
	dma_wd.fdc_acces_seccount = blocks;
	MFPDELAY();
	
	/* send last command byte */
	dma_wd.dma_mode_status = 0x8a | rwflag;
	MFPDELAY();
	DMA_LONG_WRITE( *cmd++, 0x0a | rwflag );
	if (enable)
		ENABLE_IRQ();
	udelay(80);

	return( 1 );
}


/*
 * acsicmd_nodma() sends an ACSI command that requires no DMA.
 */

int acsicmd_nodma( const char *cmd, int enable)

{	int	i;

	acsi_delay_end(COMMAND_DELAY);
	DISABLE_IRQ();

	/* send first command byte */
	dma_wd.dma_mode_status = 0x88;
	MFPDELAY();
	DMA_LONG_WRITE( *cmd++, 0x8a );
	udelay(20);
	if (!acsi_wait_for_IRQ( HZ/2 )) return( 0 ); /* timeout */

	/* send the intermediate command bytes */
	for( i = 0; i < 4; ++i ) {
		DMA_LONG_WRITE( *cmd++, 0x8a );
		udelay(20);
		if (!acsi_wait_for_IRQ( HZ/2 )) return( 0 ); /* timeout */
	}

	/* send last command byte */
	DMA_LONG_WRITE( *cmd++, 0x0a );
	if (enable)
		ENABLE_IRQ();
	udelay(80);
	
	return( 1 );
	/* Note that the ACSI interrupt is still disabled after this
	 * function. If you want to get the IRQ delivered, enable it manually!
	 */
}


static int acsi_reqsense( char *buffer, int targ, int lun)

{
	CMDSET_TARG_LUN( reqsense_cmd, targ, lun);
	if (!acsicmd_dma( reqsense_cmd, buffer, 1, 0, 0 )) return( 0 );
	if (!acsi_wait_for_IRQ( 10 )) return( 0 );
	acsi_getstatus();
	if (!acsicmd_nodma( reqsense_cmd, 0 )) return( 0 );
	if (!acsi_wait_for_IRQ( 10 )) return( 0 );
	acsi_getstatus();
	if (!acsicmd_nodma( reqsense_cmd, 0 )) return( 0 );
	if (!acsi_wait_for_IRQ( 10 )) return( 0 );
	acsi_getstatus();
	if (!acsicmd_nodma( reqsense_cmd, 0 )) return( 0 );
	if (!acsi_wait_for_IRQ( 10 )) return( 0 );
	acsi_getstatus();
	dma_cache_maintenance( virt_to_phys(buffer), 16, 0 );
	
	return( 1 );
}	


/*
 * ACSI status phase: get the status byte from the bus
 *
 * I've seen several times that a 0xff status is read, propably due to
 * a timing error. In this case, the procedure is repeated after the
 * next _IRQ edge.
 */

int acsi_getstatus( void )

{	int	status;

	DISABLE_IRQ();
	for(;;) {
		if (!acsi_wait_for_IRQ( 100 )) {
			acsi_delay_start();
			return( -1 );
		}
		dma_wd.dma_mode_status = 0x8a;
		MFPDELAY();
		status = dma_wd.fdc_acces_seccount;
		if (status != 0xff) break;
#ifdef DEBUG
		printk("ACSI: skipping 0xff status byte\n" );
#endif
		udelay(40);
		acsi_wait_for_noIRQ( 20 );
	}
	dma_wd.dma_mode_status = 0x80;
	udelay(40);
	acsi_wait_for_noIRQ( 20 );

	acsi_delay_start();
	return( status & 0x1f ); /* mask of the device# */
}


#if (defined(CONFIG_ATARI_SLM) || defined(CONFIG_ATARI_SLM_MODULE))

/* Receive data in an extended status phase. Needed by SLM printer. */

int acsi_extstatus( char *buffer, int cnt )

{	int	status;

	DISABLE_IRQ();
	udelay(80);
	while( cnt-- > 0 ) {
		if (!acsi_wait_for_IRQ( 40 )) return( 0 );
		dma_wd.dma_mode_status = 0x8a;
		MFPDELAY();
		status = dma_wd.fdc_acces_seccount;
		MFPDELAY();
		*buffer++ = status & 0xff;
		udelay(40);
	}
	return( 1 );
}


/* Finish an extended status phase */

void acsi_end_extstatus( void )

{
	dma_wd.dma_mode_status = 0x80;
	udelay(40);
	acsi_wait_for_noIRQ( 20 );
	acsi_delay_start();
}


/* Send data in an extended command phase */

int acsi_extcmd( unsigned char *buffer, int cnt )

{
	while( cnt-- > 0 ) {
		DMA_LONG_WRITE( *buffer++, 0x8a );
		udelay(20);
		if (!acsi_wait_for_IRQ( HZ/2 )) return( 0 ); /* timeout */
	}
	return( 1 );
}

#endif


static void acsi_print_error( const unsigned char *errblk, int dev  )

{	int atari_err, i, errcode;
	struct acsi_error *arr;

	atari_err = acsi_info[dev].old_atari_disk;
	if (atari_err)
		errcode = errblk[0] & 0x7f;
	else
		if ((errblk[0] & 0x70) == 0x70)
			errcode = errblk[2] & 0x0f;
		else
			errcode = errblk[0] & 0x0f;
	
	printk( KERN_ERR "ACSI error 0x%02x", errcode );

	if (errblk[0] & 0x80)
		printk( " for sector %d",
				((errblk[1] & 0x1f) << 16) |
				(errblk[2] << 8) | errblk[0] );

	arr = atari_err ? atari_acsi_errors : scsi_acsi_errors;
	i = atari_err ? sizeof(atari_acsi_errors)/sizeof(*atari_acsi_errors) :
		            sizeof(scsi_acsi_errors)/sizeof(*scsi_acsi_errors);
	
	for( --i; i >= 0; --i )
		if (arr[i].code == errcode) break;
	if (i >= 0)
		printk( ": %s\n", arr[i].text );
}

/*******************************************************************
 *
 * ACSI interrupt routine
 *   Test, if this is a ACSI interrupt and call the irq handler
 *   Otherwise ignore this interrupt.
 *
 *******************************************************************/

static void acsi_interrupt(int irq, void *data, struct pt_regs *fp )

{	void (*acsi_irq_handler)(void) = DEVICE_INTR;

	DEVICE_INTR = NULL;
	CLEAR_TIMER();

	if (!acsi_irq_handler)
		acsi_irq_handler = unexpected_acsi_interrupt;
	acsi_irq_handler();
}


/******************************************************************
 *
 * The Interrupt handlers
 *
 *******************************************************************/


static void unexpected_acsi_interrupt( void )

{
	printk( KERN_WARNING "Unexpected ACSI interrupt\n" );
}


/* This function is called in case of errors. Because we cannot reset
 * the ACSI bus or a single device, there is no other choice than
 * retrying several times :-(
 */

static void bad_rw_intr( void )

{
	if (QUEUE_EMPTY)
		return;

	if (++CURRENT->errors >= MAX_ERRORS)
		end_request(0);
	/* Otherwise just retry */
}


static void read_intr( void )

{	int		status;
	
	status = acsi_getstatus();
	if (status != 0) {
		int dev = DEVICE_NR(MINOR(CURRENT->rq_dev));
		printk( KERN_ERR "ad%c: ", dev+'a' );
		if (!acsi_reqsense( acsi_buffer, acsi_info[dev].target, 
					acsi_info[dev].lun))
			printk( "ACSI error and REQUEST SENSE failed (status=0x%02x)\n", status );
		else {
			acsi_print_error( acsi_buffer, dev );
			if (CARTRCH_STAT( dev, acsi_buffer ))
				acsi_info[dev].changed = 1;
		}
		ENABLE_IRQ();
		bad_rw_intr();
		redo_acsi_request();
		return;
	}

	dma_cache_maintenance( virt_to_phys(CurrentBuffer), CurrentNSect*512, 0 );
	if (CurrentBuffer == acsi_buffer)
		copy_from_acsibuffer();

	do_end_requests();
	redo_acsi_request();
}


static void write_intr(void)

{	int	status;

	status = acsi_getstatus();
	if (status != 0) {
		int	dev = DEVICE_NR(MINOR(CURRENT->rq_dev));
		printk( KERN_ERR "ad%c: ", dev+'a' );
		if (!acsi_reqsense( acsi_buffer, acsi_info[dev].target,
					acsi_info[dev].lun))
			printk( "ACSI error and REQUEST SENSE failed (status=0x%02x)\n", status );
		else {
			acsi_print_error( acsi_buffer, dev );
			if (CARTRCH_STAT( dev, acsi_buffer ))
				acsi_info[dev].changed = 1;
		}
		bad_rw_intr();
		redo_acsi_request();
		return;
	}

	do_end_requests();
	redo_acsi_request();
}


static void acsi_times_out( unsigned long dummy )

{
	DISABLE_IRQ();
	if (!DEVICE_INTR) return;

	DEVICE_INTR = NULL;
	printk( KERN_ERR "ACSI timeout\n" );
	if (QUEUE_EMPTY) return;
	if (++CURRENT->errors >= MAX_ERRORS) {
#ifdef DEBUG
		printk( KERN_ERR "ACSI: too many errors.\n" );
#endif
		end_request(0);
	}

	redo_acsi_request();
}



/***********************************************************************
 *
 *  Scatter-gather utility functions
 *
 ***********************************************************************/


static void copy_to_acsibuffer( void )

{	int					i;
	char				*src, *dst;
	struct buffer_head	*bh;
	
	src = CURRENT->buffer;
	dst = acsi_buffer;
	bh = CURRENT->bh;

	if (!bh)
		memcpy( dst, src, CurrentNSect*512 );
	else
		for( i = 0; i < CurrentNReq; ++i ) {
			memcpy( dst, src, bh->b_size );
			dst += bh->b_size;
			if ((bh = bh->b_reqnext))
				src = bh->b_data;
		}
}


static void copy_from_acsibuffer( void )

{	int					i;
	char				*src, *dst;
	struct buffer_head	*bh;
	
	dst = CURRENT->buffer;
	src = acsi_buffer;
	bh = CURRENT->bh;

	if (!bh)
		memcpy( dst, src, CurrentNSect*512 );
	else
		for( i = 0; i < CurrentNReq; ++i ) {
			memcpy( dst, src, bh->b_size );
			src += bh->b_size;
			if ((bh = bh->b_reqnext))
				dst = bh->b_data;
		}
}


static void do_end_requests( void )

{	int		i, n;

	if (!CURRENT->bh) {
		CURRENT->nr_sectors -= CurrentNSect;
		CURRENT->current_nr_sectors -= CurrentNSect;
		CURRENT->sector += CurrentNSect;
		if (CURRENT->nr_sectors == 0)
			end_request(1);
	}
	else {
		for( i = 0; i < CurrentNReq; ++i ) {
			n = CURRENT->bh->b_size >> 9;
			CURRENT->nr_sectors -= n;
			CURRENT->current_nr_sectors -= n;
			CURRENT->sector += n;
			end_request(1);
		}
	}
}




/***********************************************************************
 *
 *  do_acsi_request and friends
 *
 ***********************************************************************/

static void do_acsi_request( request_queue_t * q )

{
	stdma_lock( acsi_interrupt, NULL );
	redo_acsi_request();
}


static void redo_acsi_request( void )

{	unsigned			block, dev, target, lun, nsect;
	char 				*buffer;
	unsigned long		pbuffer;
	struct buffer_head	*bh;
	
	if (!QUEUE_EMPTY && CURRENT->rq_status == RQ_INACTIVE) {
		if (!DEVICE_INTR) {
			ENABLE_IRQ();
			stdma_release();
		}
		return;
	}