atari_scsi.c

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			   */
			if (atari_dma_residual & 0x1ff) {
				DMA_PRINTK("SCSI DMA: DMA bug corrected, "
					   "difference %ld bytes\n",
					   512 - (atari_dma_residual & 0x1ff));
				atari_dma_residual = (atari_dma_residual + 511) & ~0x1ff;
			}
		}
		tt_scsi_dma.dma_ctrl = 0;
	}

	/* If the DMA is finished, fetch the rest bytes and turn it off */
	if (dma_stat & 0x40) {
		atari_dma_residual = 0;
		if ((dma_stat & 1) == 0)
			atari_scsi_fetch_restbytes();
		tt_scsi_dma.dma_ctrl = 0;
	}

#endif /* REAL_DMA */
	
	NCR5380_intr (0, 0, 0);

#if 0
	/* To be sure the int is not masked */
	atari_enable_irq( IRQ_TT_MFP_SCSI );
#endif
}


static void scsi_falcon_intr (int irq, void *dummy, struct pt_regs *fp)
{
#ifdef REAL_DMA
	int dma_stat;

	/* Turn off DMA and select sector counter register before
	 * accessing the status register (Atari recommendation!)
	 */
	st_dma.dma_mode_status = 0x90;
	dma_stat = st_dma.dma_mode_status;

	/* Bit 0 indicates some error in the DMA process... don't know
	 * what happened exactly (no further docu).
	 */
	if (!(dma_stat & 0x01)) {
		/* DMA error */
		printk(KERN_CRIT "SCSI DMA error near 0x%08lx!\n", SCSI_DMA_GETADR());
	}

	/* If the DMA was active, but now bit 1 is not clear, it is some
	 * other 5380 interrupt that finishes the DMA transfer. We have to
	 * calculate the number of residual bytes and give a warning if
	 * bytes are stuck in the ST-DMA fifo (there's no way to reach them!)
	 */
	if (atari_dma_active && (dma_stat & 0x02)) {
		unsigned long	transferred;

		transferred = SCSI_DMA_GETADR() - atari_dma_startaddr;
		/* The ST-DMA address is incremented in 2-byte steps, but the
		 * data are written only in 16-byte chunks. If the number of
		 * transferred bytes is not divisible by 16, the remainder is
		 * lost somewhere in outer space.
		 */
		if (transferred & 15)
			printk(KERN_ERR "SCSI DMA error: %ld bytes lost in "
			       "ST-DMA fifo\n", transferred & 15);

		atari_dma_residual = HOSTDATA_DMALEN - transferred;
		DMA_PRINTK("SCSI DMA: There are %ld residual bytes.\n",
			   atari_dma_residual);
	}
	else
		atari_dma_residual = 0;
	atari_dma_active = 0;

	if (atari_dma_orig_addr) {
		/* If the dribble buffer was used on a read operation, copy the DMA-ed
		 * data to the original destination address.
		 */
		memcpy(atari_dma_orig_addr, phys_to_virt(atari_dma_startaddr),
		       HOSTDATA_DMALEN - atari_dma_residual);
		atari_dma_orig_addr = NULL;
	}

#endif /* REAL_DMA */

	NCR5380_intr (0, 0, 0);
}


#ifdef REAL_DMA
static void atari_scsi_fetch_restbytes( void )
{
	int nr;
	char *src, *dst;
	unsigned long phys_dst;

	/* fetch rest bytes in the DMA register */
	phys_dst = SCSI_DMA_READ_P(dma_addr);
	nr = phys_dst & 3;
	if (nr) {
		/* there are 'nr' bytes left for the last long address
		   before the DMA pointer */
		phys_dst ^= nr;
		DMA_PRINTK("SCSI DMA: there are %d rest bytes for phys addr 0x%08lx",
			   nr, phys_dst);
		/* The content of the DMA pointer is a physical address!  */
		dst = phys_to_virt(phys_dst);
		DMA_PRINTK(" = virt addr %p\n", dst);
		for (src = (char *)&tt_scsi_dma.dma_restdata; nr != 0; --nr)
			*dst++ = *src++;
	}
}
#endif /* REAL_DMA */


static int falcon_got_lock = 0;
static DECLARE_WAIT_QUEUE_HEAD(falcon_fairness_wait);
static int falcon_trying_lock = 0;
static DECLARE_WAIT_QUEUE_HEAD(falcon_try_wait);
static int falcon_dont_release = 0;

/* This function releases the lock on the DMA chip if there is no
 * connected command and the disconnected queue is empty. On
 * releasing, instances of falcon_get_lock are awoken, that put
 * themselves to sleep for fairness. They can now try to get the lock
 * again (but others waiting longer more probably will win).
 */

static void
falcon_release_lock_if_possible( struct NCR5380_hostdata * hostdata )
{
	unsigned long	oldflags;
		
	if (IS_A_TT()) return;
	
	save_flags(oldflags);
	cli();

	if (falcon_got_lock &&
		!hostdata->disconnected_queue &&
		!hostdata->issue_queue &&
		!hostdata->connected) {

		if (falcon_dont_release) {
#if 0
			printk("WARNING: Lock release not allowed. Ignored\n");
#endif
			restore_flags(oldflags);
			return;
		}
		falcon_got_lock = 0;
		stdma_release();
		wake_up( &falcon_fairness_wait );
	}

	restore_flags(oldflags);
}

/* This function manages the locking of the ST-DMA.
 * If the DMA isn't locked already for SCSI, it tries to lock it by
 * calling stdma_lock(). But if the DMA is locked by the SCSI code and
 * there are other drivers waiting for the chip, we do not issue the
 * command immediately but wait on 'falcon_fairness_queue'. We will be
 * waked up when the DMA is unlocked by some SCSI interrupt. After that
 * we try to get the lock again.
 * But we must be prepared that more than one instance of
 * falcon_get_lock() is waiting on the fairness queue. They should not
 * try all at once to call stdma_lock(), one is enough! For that, the
 * first one sets 'falcon_trying_lock', others that see that variable
 * set wait on the queue 'falcon_try_wait'.
 * Complicated, complicated.... Sigh...
 */

static void falcon_get_lock( void )
{
	unsigned long	oldflags;

	if (IS_A_TT()) return;

	save_flags(oldflags);
	cli();

	while( !in_interrupt() && falcon_got_lock && stdma_others_waiting() )
		sleep_on( &falcon_fairness_wait );

	while (!falcon_got_lock) {
		if (in_interrupt())
			panic( "Falcon SCSI hasn't ST-DMA lock in interrupt" );
		if (!falcon_trying_lock) {
			falcon_trying_lock = 1;
			stdma_lock(scsi_falcon_intr, NULL);
			falcon_got_lock = 1;
			falcon_trying_lock = 0;
			wake_up( &falcon_try_wait );
		}
		else {
			sleep_on( &falcon_try_wait );
		}
	}	

	restore_flags(oldflags);
	if (!falcon_got_lock)
		panic("Falcon SCSI: someone stole the lock :-(\n");
}


/* This is the wrapper function for NCR5380_queue_command(). It just
 * tries to get the lock on the ST-DMA (see above) and then calls the
 * original function.
 */

#if 0
int atari_queue_command (Scsi_Cmnd *cmd, void (*done)(Scsi_Cmnd *))
{
	/* falcon_get_lock();
	 * ++guenther: moved to NCR5380_queue_command() to prevent
	 * race condition, see there for an explanation.
	 */
	return( NCR5380_queue_command( cmd, done ) );
}
#endif


int atari_scsi_detect (Scsi_Host_Template *host)
{
	static int called = 0;
	struct Scsi_Host *instance;

	if (!MACH_IS_ATARI ||
	    (!ATARIHW_PRESENT(ST_SCSI) && !ATARIHW_PRESENT(TT_SCSI)) ||
	    called)
		return( 0 );

	host->proc_name = "Atari";

	atari_scsi_reg_read  = IS_A_TT() ? atari_scsi_tt_reg_read :
					   atari_scsi_falcon_reg_read;
	atari_scsi_reg_write = IS_A_TT() ? atari_scsi_tt_reg_write :
					   atari_scsi_falcon_reg_write;

	/* setup variables */
	host->can_queue =
		(setup_can_queue > 0) ? setup_can_queue :
		IS_A_TT() ? ATARI_TT_CAN_QUEUE : ATARI_FALCON_CAN_QUEUE;
	host->cmd_per_lun =
		(setup_cmd_per_lun > 0) ? setup_cmd_per_lun :
		IS_A_TT() ? ATARI_TT_CMD_PER_LUN : ATARI_FALCON_CMD_PER_LUN;
	/* Force sg_tablesize to 0 on a Falcon! */
	host->sg_tablesize =
		!IS_A_TT() ? ATARI_FALCON_SG_TABLESIZE :
		(setup_sg_tablesize >= 0) ? setup_sg_tablesize : ATARI_TT_SG_TABLESIZE;

	if (setup_hostid >= 0)
		host->this_id = setup_hostid;
	else {
		/* use 7 as default */
		host->this_id = 7;
		/* Test if a host id is set in the NVRam */
		if (ATARIHW_PRESENT(TT_CLK) && nvram_check_checksum()) {
			unsigned char b = nvram_read_byte( 14 );
			/* Arbitration enabled? (for TOS) If yes, use configured host ID */
			if (b & 0x80)
				host->this_id = b & 7;
		}
	}

#ifdef SUPPORT_TAGS
	if (setup_use_tagged_queuing < 0)
		setup_use_tagged_queuing = DEFAULT_USE_TAGGED_QUEUING;
#endif
#ifdef REAL_DMA
	/* If running on a Falcon and if there's TT-Ram (i.e., more than one
	 * memory block, since there's always ST-Ram in a Falcon), then allocate a
	 * STRAM_BUFFER_SIZE byte dribble buffer for transfers from/to alternative
	 * Ram.
	 */
	if (MACH_IS_ATARI && ATARIHW_PRESENT(ST_SCSI) &&
	    !ATARIHW_PRESENT(EXTD_DMA) && m68k_num_memory > 1) {
		atari_dma_buffer = atari_stram_alloc(STRAM_BUFFER_SIZE, "SCSI");
		if (!atari_dma_buffer) {
			printk( KERN_ERR "atari_scsi_detect: can't allocate ST-RAM "
					"double buffer\n" );
			return( 0 );
		}
		atari_dma_phys_buffer = virt_to_phys( atari_dma_buffer );
		atari_dma_orig_addr = 0;
	}
#endif
	instance = scsi_register (host, sizeof (struct NCR5380_hostdata));
	if(instance == NULL)
	{
		atari_stram_free(atari_dma_buffer);
		atari_dma_buffer = 0;
		return 0;
	}
	atari_scsi_host = instance;
       /* Set irq to 0, to avoid that the mid-level code disables our interrupt
        * during queue_command calls. This is completely unnecessary, and even
        * worse causes bad problems on the Falcon, where the int is shared with
        * IDE and floppy! */
       instance->irq = 0;

#ifdef CONFIG_ATARI_SCSI_RESET_BOOT
	atari_scsi_reset_boot();
#endif
	NCR5380_init (instance, 0);

	if (IS_A_TT()) {

		/* This int is actually "pseudo-slow", i.e. it acts like a slow
		 * interrupt after having cleared the pending flag for the DMA
		 * interrupt. */
		request_irq(IRQ_TT_MFP_SCSI, scsi_tt_intr, IRQ_TYPE_SLOW,
		            "SCSI NCR5380", scsi_tt_intr);
		tt_mfp.active_edge |= 0x80;		/* SCSI int on L->H */
#ifdef REAL_DMA
		tt_scsi_dma.dma_ctrl = 0;
		atari_dma_residual = 0;
#endif /* REAL_DMA */
#ifdef REAL_DMA
#ifdef CONFIG_TT_DMA_EMUL
		if (MACH_IS_HADES) {
			request_irq(IRQ_AUTO_2, hades_dma_emulator,
				    IRQ_TYPE_PRIO, "Hades DMA emulator",
				    hades_dma_emulator);
		}
#endif
		if (MACH_IS_MEDUSA || MACH_IS_HADES) {
			/* While the read overruns (described by Drew Eckhardt in
			 * NCR5380.c) never happened on TTs, they do in fact on the Medusa
			 * (This was the cause why SCSI didn't work right for so long
			 * there.) Since handling the overruns slows down a bit, I turned
			 * the #ifdef's into a runtime condition.
			 *
			 * In principle it should be sufficient to do max. 1 byte with
			 * PIO, but there is another problem on the Medusa with the DMA
			 * rest data register. So 'atari_read_overruns' is currently set
			 * to 4 to avoid having transfers that aren't a multiple of 4. If
			 * the rest data bug is fixed, this can be lowered to 1.
			 */
			atari_read_overruns = 4;
		}
#endif
		
	}
	else { /* ! IS_A_TT */
		
		/* Nothing to do for the interrupt: the ST-DMA is initialized
		 * already by atari_init_INTS()
		 */

#ifdef REAL_DMA
		atari_dma_residual = 0;
		atari_dma_active = 0;
		atari_dma_stram_mask = (ATARIHW_PRESENT(EXTD_DMA) ? 0x00000000
					: 0xff000000);
#endif
	}

	printk(KERN_INFO "scsi%d: options CAN_QUEUE=%d CMD_PER_LUN=%d SCAT-GAT=%d "
#ifdef SUPPORT_TAGS
			"TAGGED-QUEUING=%s "
#endif
			"HOSTID=%d",
			instance->host_no, instance->hostt->can_queue,
			instance->hostt->cmd_per_lun,
			instance->hostt->sg_tablesize,
#ifdef SUPPORT_TAGS
			setup_use_tagged_queuing ? "yes" : "no",
#endif
			instance->hostt->this_id );
	NCR5380_print_options (instance);
	printk ("\n");

	called = 1;
	return( 1 );
}