atari_scsi.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

#ifdef MODULE
int atari_scsi_release (struct Scsi_Host *sh)
{
	if (IS_A_TT())
		free_irq(IRQ_TT_MFP_SCSI, scsi_tt_intr);
	if (atari_dma_buffer)
		atari_stram_free (atari_dma_buffer);
	return 1;
}
#endif

void __init atari_scsi_setup(char *str, int *ints)
{
	/* Format of atascsi parameter is:
	 *   atascsi=<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
	 * Defaults depend on TT or Falcon, hostid determined at run time.
	 * Negative values mean don't change.
	 */
	
	if (ints[0] < 1) {
		printk( "atari_scsi_setup: no arguments!\n" );
		return;
	}

	if (ints[0] >= 1) {
		if (ints[1] > 0)
			/* no limits on this, just > 0 */
			setup_can_queue = ints[1];
	}
	if (ints[0] >= 2) {
		if (ints[2] > 0)
			setup_cmd_per_lun = ints[2];
	}
	if (ints[0] >= 3) {
		if (ints[3] >= 0) {
			setup_sg_tablesize = ints[3];
			/* Must be <= SG_ALL (255) */
			if (setup_sg_tablesize > SG_ALL)
				setup_sg_tablesize = SG_ALL;
		}
	}
	if (ints[0] >= 4) {
		/* Must be between 0 and 7 */
		if (ints[4] >= 0 && ints[4] <= 7)
			setup_hostid = ints[4];
		else if (ints[4] > 7)
			printk( "atari_scsi_setup: invalid host ID %d !\n", ints[4] );
	}
#ifdef SUPPORT_TAGS
	if (ints[0] >= 5) {
		if (ints[5] >= 0)
			setup_use_tagged_queuing = !!ints[5];
	}
#endif
}

int atari_scsi_reset( Scsi_Cmnd *cmd, unsigned int reset_flags)
{
	int		rv;
	struct NCR5380_hostdata *hostdata =
		(struct NCR5380_hostdata *)cmd->host->hostdata;

	/* For doing the reset, SCSI interrupts must be disabled first,
	 * since the 5380 raises its IRQ line while _RST is active and we
	 * can't disable interrupts completely, since we need the timer.
	 */
	/* And abort a maybe active DMA transfer */
	if (IS_A_TT()) {
		atari_turnoff_irq( IRQ_TT_MFP_SCSI );
#ifdef REAL_DMA
		tt_scsi_dma.dma_ctrl = 0;
#endif /* REAL_DMA */
	}
	else {
		atari_turnoff_irq( IRQ_MFP_FSCSI );
#ifdef REAL_DMA
		st_dma.dma_mode_status = 0x90;
		atari_dma_active = 0;
		atari_dma_orig_addr = NULL;
#endif /* REAL_DMA */
	}

	rv = NCR5380_reset(cmd, reset_flags);

	/* Re-enable ints */
	if (IS_A_TT()) {
		atari_turnon_irq( IRQ_TT_MFP_SCSI );
	}
	else {
		atari_turnon_irq( IRQ_MFP_FSCSI );
	}
	if ((rv & SCSI_RESET_ACTION) == SCSI_RESET_SUCCESS)
		falcon_release_lock_if_possible(hostdata);

	return( rv );
}

	
#ifdef CONFIG_ATARI_SCSI_RESET_BOOT
static void __init atari_scsi_reset_boot(void)
{
	unsigned long end;
	
	/*
	 * Do a SCSI reset to clean up the bus during initialization. No messing
	 * with the queues, interrupts, or locks necessary here.
	 */

	printk( "Atari SCSI: resetting the SCSI bus..." );

	/* get in phase */
	NCR5380_write( TARGET_COMMAND_REG,
		      PHASE_SR_TO_TCR( NCR5380_read(STATUS_REG) ));

	/* assert RST */
	NCR5380_write( INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_RST );
	/* The min. reset hold time is 25us, so 40us should be enough */
	udelay( 50 );
	/* reset RST and interrupt */
	NCR5380_write( INITIATOR_COMMAND_REG, ICR_BASE );
	NCR5380_read( RESET_PARITY_INTERRUPT_REG );

	end = jiffies + AFTER_RESET_DELAY;
	while (time_before(jiffies, end))
		barrier();

	printk( " done\n" );
}
#endif


const char * atari_scsi_info (struct Scsi_Host *host)
{
	/* atari_scsi_detect() is verbose enough... */
	static const char string[] = "Atari native SCSI";
	return string;
}


#if defined(REAL_DMA)

unsigned long atari_scsi_dma_setup( struct Scsi_Host *instance, void *data,
				   unsigned long count, int dir )
{
	unsigned long addr = virt_to_phys( data );

	DMA_PRINTK("scsi%d: setting up dma, data = %p, phys = %lx, count = %ld, "
		   "dir = %d\n", instance->host_no, data, addr, count, dir);

	if (!IS_A_TT() && !STRAM_ADDR(addr)) {
		/* If we have a non-DMAable address on a Falcon, use the dribble
		 * buffer; 'orig_addr' != 0 in the read case tells the interrupt
		 * handler to copy data from the dribble buffer to the originally
		 * wanted address.
		 */
		if (dir)
			memcpy( atari_dma_buffer, data, count );
		else
			atari_dma_orig_addr = data;
		addr = atari_dma_phys_buffer;
	}
	
	atari_dma_startaddr = addr;	/* Needed for calculating residual later. */
  
	/* Cache cleanup stuff: On writes, push any dirty cache out before sending
	 * it to the peripheral. (Must be done before DMA setup, since at least
	 * the ST-DMA begins to fill internal buffers right after setup. For
	 * reads, invalidate any cache, may be altered after DMA without CPU
	 * knowledge.
	 * 
	 * ++roman: For the Medusa, there's no need at all for that cache stuff,
	 * because the hardware does bus snooping (fine!).
	 */
	dma_cache_maintenance( addr, count, dir );

	if (count == 0)
		printk(KERN_NOTICE "SCSI warning: DMA programmed for 0 bytes !\n");

	if (IS_A_TT()) {
		tt_scsi_dma.dma_ctrl = dir;
		SCSI_DMA_WRITE_P( dma_addr, addr );
		SCSI_DMA_WRITE_P( dma_cnt, count );
		tt_scsi_dma.dma_ctrl = dir | 2;
	}
	else { /* ! IS_A_TT */
  
		/* set address */
		SCSI_DMA_SETADR( addr );

		/* toggle direction bit to clear FIFO and set DMA direction */
		dir <<= 8;
		st_dma.dma_mode_status = 0x90 | dir;
		st_dma.dma_mode_status = 0x90 | (dir ^ 0x100);
		st_dma.dma_mode_status = 0x90 | dir;
		udelay(40);
		/* On writes, round up the transfer length to the next multiple of 512
		 * (see also comment at atari_dma_xfer_len()). */
		st_dma.fdc_acces_seccount = (count + (dir ? 511 : 0)) >> 9;
		udelay(40);
		st_dma.dma_mode_status = 0x10 | dir;
		udelay(40);
		/* need not restore value of dir, only boolean value is tested */
		atari_dma_active = 1;
	}

	return( count );
}


static long atari_scsi_dma_residual( struct Scsi_Host *instance )
{
	return( atari_dma_residual );
}


#define	CMD_SURELY_BLOCK_MODE	0
#define	CMD_SURELY_BYTE_MODE	1
#define	CMD_MODE_UNKNOWN		2

static int falcon_classify_cmd( Scsi_Cmnd *cmd )
{
	unsigned char opcode = cmd->cmnd[0];
	
	if (opcode == READ_DEFECT_DATA || opcode == READ_LONG ||
		opcode == READ_BUFFER)
		return( CMD_SURELY_BYTE_MODE );
	else if (opcode == READ_6 || opcode == READ_10 ||
		 opcode == 0xa8 /* READ_12 */ || opcode == READ_REVERSE ||
		 opcode == RECOVER_BUFFERED_DATA) {
		/* In case of a sequential-access target (tape), special care is
		 * needed here: The transfer is block-mode only if the 'fixed' bit is
		 * set! */
		if (cmd->device->type == TYPE_TAPE && !(cmd->cmnd[1] & 1))
			return( CMD_SURELY_BYTE_MODE );
		else
			return( CMD_SURELY_BLOCK_MODE );
	}
	else
		return( CMD_MODE_UNKNOWN );
}


/* This function calculates the number of bytes that can be transferred via
 * DMA. On the TT, this is arbitrary, but on the Falcon we have to use the
 * ST-DMA chip. There are only multiples of 512 bytes possible and max.
 * 255*512 bytes :-( This means also, that defining READ_OVERRUNS is not
 * possible on the Falcon, since that would require to program the DMA for
 * n*512 - atari_read_overrun bytes. But it seems that the Falcon doesn't have
 * the overrun problem, so this question is academic :-)
 */

static unsigned long atari_dma_xfer_len( unsigned long wanted_len,
					Scsi_Cmnd *cmd,
					int write_flag )
{
	unsigned long	possible_len, limit;
#ifndef CONFIG_TT_DMA_EMUL
	if (MACH_IS_HADES)
		/* Hades has no SCSI DMA at all :-( Always force use of PIO */
		return( 0 );
#endif	
	if (IS_A_TT())
		/* TT SCSI DMA can transfer arbitrary #bytes */
		return( wanted_len );

	/* ST DMA chip is stupid -- only multiples of 512 bytes! (and max.
	 * 255*512 bytes, but this should be enough)
	 *
	 * ++roman: Aaargl! Another Falcon-SCSI problem... There are some commands
	 * that return a number of bytes which cannot be known beforehand. In this
	 * case, the given transfer length is an "allocation length". Now it
	 * can happen that this allocation length is a multiple of 512 bytes and
	 * the DMA is used. But if not n*512 bytes really arrive, some input data
	 * will be lost in the ST-DMA's FIFO :-( Thus, we have to distinguish
	 * between commands that do block transfers and those that do byte
	 * transfers. But this isn't easy... there are lots of vendor specific
	 * commands, and the user can issue any command via the
	 * SCSI_IOCTL_SEND_COMMAND.
	 *
	 * The solution: We classify SCSI commands in 1) surely block-mode cmd.s,
	 * 2) surely byte-mode cmd.s and 3) cmd.s with unknown mode. In case 1)
	 * and 3), the thing to do is obvious: allow any number of blocks via DMA
	 * or none. In case 2), we apply some heuristic: Byte mode is assumed if
	 * the transfer (allocation) length is < 1024, hoping that no cmd. not
	 * explicitly known as byte mode have such big allocation lengths...
	 * BTW, all the discussion above applies only to reads. DMA writes are
	 * unproblematic anyways, since the targets aborts the transfer after
	 * receiving a sufficient number of bytes.
	 *
	 * Another point: If the transfer is from/to an non-ST-RAM address, we
	 * use the dribble buffer and thus can do only STRAM_BUFFER_SIZE bytes.
	 */

	if (write_flag) {
		/* Write operation can always use the DMA, but the transfer size must
		 * be rounded up to the next multiple of 512 (atari_dma_setup() does
		 * this).
		 */
		possible_len = wanted_len;
	}
	else {
		/* Read operations: if the wanted transfer length is not a multiple of
		 * 512, we cannot use DMA, since the ST-DMA cannot split transfers
		 * (no interrupt on DMA finished!)
		 */
		if (wanted_len & 0x1ff)
			possible_len = 0;
		else {
			/* Now classify the command (see above) and decide whether it is
			 * allowed to do DMA at all */
			switch( falcon_classify_cmd( cmd )) {
			  case CMD_SURELY_BLOCK_MODE:
				possible_len = wanted_len;
				break;
			  case CMD_SURELY_BYTE_MODE:
				possible_len = 0; /* DMA prohibited */
				break;
			  case CMD_MODE_UNKNOWN:
			  default:
				/* For unknown commands assume block transfers if the transfer
				 * size/allocation length is >= 1024 */
				possible_len = (wanted_len < 1024) ? 0 : wanted_len;
				break;
			}
		}
	}
	
	/* Last step: apply the hard limit on DMA transfers */
	limit = (atari_dma_buffer && !STRAM_ADDR( virt_to_phys(cmd->SCp.ptr) )) ?
		    STRAM_BUFFER_SIZE : 255*512;
	if (possible_len > limit)
		possible_len = limit;

	if (possible_len != wanted_len)
		DMA_PRINTK("Sorry, must cut DMA transfer size to %ld bytes "
			   "instead of %ld\n", possible_len, wanted_len);

	return( possible_len );
}


#endif	/* REAL_DMA */


/* NCR5380 register access functions
 *
 * There are separate functions for TT and Falcon, because the access
 * methods are quite different. The calling macros NCR5380_read and
 * NCR5380_write call these functions via function pointers.
 */

static unsigned char atari_scsi_tt_reg_read( unsigned char reg )
{
	return( tt_scsi_regp[reg * 2] );
}

static void atari_scsi_tt_reg_write( unsigned char reg, unsigned char value )
{
	tt_scsi_regp[reg * 2] = value;
}

static unsigned char atari_scsi_falcon_reg_read( unsigned char reg )
{
	dma_wd.dma_mode_status= (u_short)(0x88 + reg);
	return( (u_char)dma_wd.fdc_acces_seccount );
}

static void atari_scsi_falcon_reg_write( unsigned char reg, unsigned char value )
{
	dma_wd.dma_mode_status = (u_short)(0x88 + reg);
	dma_wd.fdc_acces_seccount = (u_short)value;
}


#include "atari_NCR5380.c"

static Scsi_Host_Template driver_template = ATARI_SCSI;
#include "scsi_module.c"