patch-2.4.3 linux/drivers/scsi/aic7xxx_old/aic7xxx.seq

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diff -u --recursive --new-file v2.4.2/linux/drivers/scsi/aic7xxx_old/aic7xxx.seq linux/drivers/scsi/aic7xxx_old/aic7xxx.seq
@@ -0,0 +1,1411 @@
+/*
+ * Adaptec 274x/284x/294x device driver firmware for Linux and FreeBSD.
+ *
+ * Copyright (c) 1994-1999 Justin Gibbs.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification, immediately at the beginning of the file.
+ * 2. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * Where this Software is combined with software released under the terms of 
+ * the GNU Public License (GPL) and the terms of the GPL would require the 
+ * combined work to also be released under the terms of the GPL, the terms
+ * and conditions of this License will apply in addition to those of the
+ * GPL with the exception of any terms or conditions of this License that
+ * conflict with, or are expressly prohibited by, the GPL.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	$Id: aic7xxx.seq,v 1.77 1998/06/28 02:58:57 gibbs Exp $
+ */
+
+#include "aic7xxx.reg"
+#include "scsi_message.h"
+
+/*
+ * A few words on the waiting SCB list:
+ * After starting the selection hardware, we check for reconnecting targets
+ * as well as for our selection to complete just in case the reselection wins
+ * bus arbitration.  The problem with this is that we must keep track of the
+ * SCB that we've already pulled from the QINFIFO and started the selection
+ * on just in case the reselection wins so that we can retry the selection at
+ * a later time.  This problem cannot be resolved by holding a single entry
+ * in scratch ram since a reconnecting target can request sense and this will
+ * create yet another SCB waiting for selection.  The solution used here is to 
+ * use byte 27 of the SCB as a pseudo-next pointer and to thread a list
+ * of SCBs that are awaiting selection.  Since 0-0xfe are valid SCB indexes, 
+ * SCB_LIST_NULL is 0xff which is out of range.  An entry is also added to
+ * this list everytime a request sense occurs or after completing a non-tagged
+ * command for which a second SCB has been queued.  The sequencer will
+ * automatically consume the entries.
+ */
+
+reset:
+	clr	SCSISIGO;		/* De-assert BSY */
+	and	SXFRCTL1, ~BITBUCKET;
+	/* Always allow reselection */
+	mvi	SCSISEQ, ENRSELI|ENAUTOATNP;
+
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		/* Ensure that no DMA operations are in progress */
+		clr	CCSGCTL;
+		clr	CCSCBCTL;
+	}
+
+	call	clear_target_state;
+poll_for_work:
+	and	SXFRCTL0, ~SPIOEN;
+	if ((p->features & AHC_QUEUE_REGS) == 0) {
+		mov	A, QINPOS;
+	}
+poll_for_work_loop:
+	if ((p->features & AHC_QUEUE_REGS) == 0) {
+		and	SEQCTL, ~PAUSEDIS;
+	}
+	test	SSTAT0, SELDO|SELDI	jnz selection;
+	test	SCSISEQ, ENSELO	jnz poll_for_work;
+	if ((p->features & AHC_TWIN) != 0) {
+		/*
+		 * Twin channel devices cannot handle things like SELTO
+		 * interrupts on the "background" channel.  So, if we
+		 * are selecting, keep polling the current channel util
+		 * either a selection or reselection occurs.
+		 */
+		xor	SBLKCTL,SELBUSB;	/* Toggle to the other bus */
+		test	SSTAT0, SELDO|SELDI	jnz selection;
+		test	SCSISEQ, ENSELO	jnz poll_for_work;
+		xor	SBLKCTL,SELBUSB;	/* Toggle back */
+	}
+	cmp	WAITING_SCBH,SCB_LIST_NULL jne start_waiting;
+test_queue:
+	/* Has the driver posted any work for us? */
+	if ((p->features & AHC_QUEUE_REGS) != 0) {
+		test	QOFF_CTLSTA, SCB_AVAIL jz poll_for_work_loop;
+		mov	NONE, SNSCB_QOFF;
+		inc	QINPOS;
+	} else {
+		or	SEQCTL, PAUSEDIS;
+		cmp	KERNEL_QINPOS, A je poll_for_work_loop;
+		inc	QINPOS;
+		and	SEQCTL, ~PAUSEDIS;
+	}
+
+/*
+ * We have at least one queued SCB now and we don't have any 
+ * SCBs in the list of SCBs awaiting selection.  If we have
+ * any SCBs available for use, pull the tag from the QINFIFO
+ * and get to work on it.
+ */
+	if ((p->flags & AHC_PAGESCBS) != 0) {
+		mov	ALLZEROS	call	get_free_or_disc_scb;
+	}
+
+dequeue_scb:
+	add	A, -1, QINPOS;
+	mvi	QINFIFO_OFFSET call fetch_byte;
+
+	if ((p->flags & AHC_PAGESCBS) == 0) {
+		/* In the non-paging case, the SCBID == hardware SCB index */
+		mov	SCBPTR, RETURN_2;
+	}
+dma_queued_scb:
+/*
+ * DMA the SCB from host ram into the current SCB location.
+ */
+	mvi	DMAPARAMS, HDMAEN|DIRECTION|FIFORESET;
+	mov	RETURN_2	 call dma_scb;
+
+/*
+ * Preset the residual fields in case we never go through a data phase.
+ * This isn't done by the host so we can avoid a DMA to clear these
+ * fields for the normal case of I/O that completes without underrun
+ * or overrun conditions.
+ */
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		bmov    SCB_RESID_DCNT, SCB_DATACNT, 3;
+	} else {
+		mov     SCB_RESID_DCNT[0],SCB_DATACNT[0];
+		mov     SCB_RESID_DCNT[1],SCB_DATACNT[1];
+		mov     SCB_RESID_DCNT[2],SCB_DATACNT[2];
+	}
+	mov     SCB_RESID_SGCNT, SCB_SGCOUNT;
+
+start_scb:
+	/*
+	 * Place us on the waiting list in case our selection
+	 * doesn't win during bus arbitration.
+	 */
+	mov	SCB_NEXT,WAITING_SCBH;
+	mov	WAITING_SCBH, SCBPTR;
+start_waiting:
+	/*
+	 * Pull the first entry off of the waiting SCB list.
+	 */
+	mov	SCBPTR, WAITING_SCBH;
+	call	start_selection;
+	jmp	poll_for_work;
+
+start_selection:
+	if ((p->features & AHC_TWIN) != 0) {
+		and	SINDEX,~SELBUSB,SBLKCTL;/* Clear channel select bit */
+		and	A,SELBUSB,SCB_TCL;	/* Get new channel bit */
+		or	SINDEX,A;
+		mov	SBLKCTL,SINDEX;		/* select channel */
+	}
+initialize_scsiid:
+	if ((p->features & AHC_ULTRA2) != 0) {
+		and	A, TID, SCB_TCL;	/* Get target ID */
+		and	SCSIID_ULTRA2, OID;	/* Clear old target */
+		or	SCSIID_ULTRA2, A;
+	} else {
+		and	A, TID, SCB_TCL;	/* Get target ID */
+		and	SCSIID, OID;		/* Clear old target */
+		or	SCSIID, A;
+	}
+	mov	SCSIDATL, ALLZEROS;		/* clear out the latched */
+						/* data register, this */
+						/* fixes a bug on some */
+						/* controllers where the */
+						/* last byte written to */
+						/* this register can leak */
+						/* onto the data bus at */
+						/* bad times, such as during */
+						/* selection timeouts */
+	mvi	SCSISEQ, ENSELO|ENAUTOATNO|ENRSELI|ENAUTOATNP ret;
+
+/*
+ * Initialize Ultra mode setting and clear the SCSI channel.
+ * SINDEX should contain any additional bit's the client wants
+ * set in SXFRCTL0.
+ */
+initialize_channel:
+	or	SXFRCTL0, CLRSTCNT|CLRCHN, SINDEX;
+	if ((p->features & AHC_ULTRA) != 0) {
+ultra:
+		mvi	SINDEX, ULTRA_ENB+1;
+		test	SAVED_TCL, 0x80		jnz ultra_2; /* Target ID > 7 */
+		dec	SINDEX;
+ultra_2:
+		mov     FUNCTION1,SAVED_TCL;
+		mov     A,FUNCTION1;
+		test	SINDIR, A	jz ndx_dtr;
+		or	SXFRCTL0, FAST20;
+	} 
+/*
+ * Initialize SCSIRATE with the appropriate value for this target.
+ * The SCSIRATE settings for each target are stored in an array
+ * based at TARG_SCSIRATE.
+ */
+ndx_dtr:
+	shr	A,4,SAVED_TCL;
+	if ((p->features & AHC_TWIN) != 0) {
+		test	SBLKCTL,SELBUSB	jz ndx_dtr_2;
+		or	SAVED_TCL, SELBUSB; 
+		or	A,0x08;			/* Channel B entries add 8 */
+ndx_dtr_2:
+	}
+
+	if ((p->features & AHC_ULTRA2) != 0) {
+		add	SINDEX, TARG_OFFSET, A;
+		mov	SCSIOFFSET, SINDIR;
+	}
+
+	add	SINDEX,TARG_SCSIRATE,A;
+	mov	SCSIRATE,SINDIR ret;
+
+
+selection:
+	test	SSTAT0,SELDO	jnz select_out;
+/*
+ * Reselection has been initiated by a target. Make a note that we've been
+ * reselected, but haven't seen an IDENTIFY message from the target yet.
+ */
+initiator_reselect:
+	mvi	CLRSINT0, CLRSELDI;
+	/* XXX test for and handle ONE BIT condition */
+	and	SAVED_TCL, SELID_MASK, SELID;
+	mvi	CLRSINT1,CLRBUSFREE;
+	or	SIMODE1, ENBUSFREE;		/*
+						 * We aren't expecting a
+						 * bus free, so interrupt
+						 * the kernel driver if it
+						 * happens.
+						 */
+	mvi	SPIOEN call	initialize_channel;
+	mvi	MSG_OUT, MSG_NOOP;		/* No message to send */
+	jmp	ITloop;
+
+/*
+ * After the selection, remove this SCB from the "waiting SCB"
+ * list.  This is achieved by simply moving our "next" pointer into
+ * WAITING_SCBH.  Our next pointer will be set to null the next time this
+ * SCB is used, so don't bother with it now.
+ */
+select_out:
+	/* Turn off the selection hardware */
+	mvi	SCSISEQ, ENRSELI|ENAUTOATNP;	/*
+						 * ATN on parity errors
+						 * for "in" phases
+						 */
+	mvi	CLRSINT0, CLRSELDO;
+	mov	SCBPTR, WAITING_SCBH;
+	mov	WAITING_SCBH,SCB_NEXT;
+	mov	SAVED_TCL, SCB_TCL;
+	mvi	CLRSINT1,CLRBUSFREE;
+	or	SIMODE1, ENBUSFREE;		/*
+						 * We aren't expecting a
+						 * bus free, so interrupt
+						 * the kernel driver if it
+						 * happens.
+						 */
+	mvi	SPIOEN call	initialize_channel;
+/*
+ * As soon as we get a successful selection, the target should go
+ * into the message out phase since we have ATN asserted.
+ */
+	mvi	MSG_OUT, MSG_IDENTIFYFLAG;
+	or	SEQ_FLAGS, IDENTIFY_SEEN;
+
+/*
+ * Main loop for information transfer phases.  Wait for the target
+ * to assert REQ before checking MSG, C/D and I/O for the bus phase.
+ */
+ITloop:
+	call	phase_lock;
+
+	mov	A, LASTPHASE;
+
+	test	A, ~P_DATAIN	jz p_data;
+	cmp	A,P_COMMAND	je p_command;
+	cmp	A,P_MESGOUT	je p_mesgout;
+	cmp	A,P_STATUS	je p_status;
+	cmp	A,P_MESGIN	je p_mesgin;
+
+	mvi	INTSTAT,BAD_PHASE;	/* unknown phase - signal driver */
+	jmp	ITloop;			/* Try reading the bus again. */
+
+await_busfree:
+	and	SIMODE1, ~ENBUSFREE;
+	call	clear_target_state;
+	mov	NONE, SCSIDATL;		/* Ack the last byte */
+	and	SXFRCTL0, ~SPIOEN;
+	test	SSTAT1,REQINIT|BUSFREE	jz .;
+	test	SSTAT1, BUSFREE jnz poll_for_work;
+	mvi	INTSTAT, BAD_PHASE;
+	
+clear_target_state:
+	/*
+	 * We assume that the kernel driver may reset us
+	 * at any time, even in the middle of a DMA, so
+	 * clear DFCNTRL too.
+	 */
+	clr	DFCNTRL;
+
+	/*
+	 * We don't know the target we will connect to,
+	 * so default to narrow transfers to avoid
+	 * parity problems.
+	 */
+	if ((p->features & AHC_ULTRA2) != 0) {
+		bmov    SCSIRATE, ALLZEROS, 2;
+	} else {
+		clr     SCSIRATE;
+		and     SXFRCTL0, ~(FAST20);
+	}
+	mvi	LASTPHASE, P_BUSFREE;
+	/* clear target specific flags */
+	clr	SEQ_FLAGS ret;
+
+/*
+ * If we re-enter the data phase after going through another phase, the
+ * STCNT may have been cleared, so restore it from the residual field.
+ */
+data_phase_reinit:
+	if ((p->features & AHC_ULTRA2) != 0) {
+		bmov	HADDR, SHADDR, 4;
+		bmov    HCNT, SCB_RESID_DCNT, 3;
+	}
+	if ((p->chip & AHC_CHIPID_MASK) == AHC_AIC7895) {
+		bmov    STCNT, SCB_RESID_DCNT, 3;
+	}
+	if ((p->features & AHC_CMD_CHAN) == 0) {
+		mvi	DINDEX, STCNT;
+		mvi	SCB_RESID_DCNT	call bcopy_3;
+	}
+	jmp	data_phase_loop;
+
+p_data:
+	if ((p->features & AHC_ULTRA2) != 0) {
+		mvi	DMAPARAMS, PRELOADEN|SCSIEN|HDMAEN;
+	} else {
+		mvi	DMAPARAMS, WIDEODD|SCSIEN|SDMAEN|HDMAEN|FIFORESET;
+	}
+	test	LASTPHASE, IOI jnz . + 2;
+	or	DMAPARAMS, DIRECTION;
+	call	assert;			/*
+					 * Ensure entering a data
+					 * phase is okay - seen identify, etc.
+					 */
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		mvi	CCSGADDR, CCSGADDR_MAX;
+	}
+	test	SEQ_FLAGS, DPHASE	jnz data_phase_reinit;
+
+	/* We have seen a data phase */
+	or	SEQ_FLAGS, DPHASE;
+
+	/*
+	 * Initialize the DMA address and counter from the SCB.
+	 * Also set SG_COUNT and SG_NEXT in memory since we cannot
+	 * modify the values in the SCB itself until we see a
+	 * save data pointers message.
+	 */
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		bmov	HADDR, SCB_DATAPTR, 7;
+		bmov    STCNT, HCNT, 3;
+		bmov    SG_COUNT, SCB_SGCOUNT, 5;
+	} else {
+		mvi	DINDEX, HADDR;
+		mvi	SCB_DATAPTR	call bcopy_7;
+		call	set_stcnt_from_hcnt;
+		mvi	DINDEX, SG_COUNT;
+		mvi	SCB_SGCOUNT	call bcopy_5;
+	}
+
+data_phase_loop:
+/* Guard against overruns */
+	test	SG_COUNT, 0xff jnz data_phase_inbounds;
+/*
+ * Turn on 'Bit Bucket' mode, set the transfer count to
+ * 16meg and let the target run until it changes phase.
+ * When the transfer completes, notify the host that we
+ * had an overrun.
+ */
+	or	SXFRCTL1,BITBUCKET;
+	and	DMAPARAMS, ~(HDMAEN|SDMAEN);
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		if ((p->features & AHC_ULTRA2) != 0) {
+			bmov	HCNT, ALLONES, 3;
+		}
+		bmov	STCNT, ALLONES, 3;
+	} else {
+		mvi	STCNT[0], 0xFF;
+		mvi	STCNT[1], 0xFF;
+		mvi	STCNT[2], 0xFF;
+	}
+data_phase_inbounds:
+/* If we are the last SG block, tell the hardware. */
+	cmp	SG_COUNT,0x01 jne data_phase_wideodd;
+	if ((p->features & AHC_ULTRA2) == 0) {
+		and	DMAPARAMS, ~WIDEODD;
+	} else {
+		mvi	SG_CACHEPTR, LAST_SEG;
+	}
+data_phase_wideodd:
+	if ((p->features & AHC_ULTRA2) != 0) {
+		mov	SINDEX, ALLONES;
+		mov	DFCNTRL, DMAPARAMS;
+		test	SSTAT0, SDONE jnz .;
+data_phase_dma_loop:
+		test	SSTAT0, SDONE jnz data_phase_dma_done;
+		test	SSTAT1,PHASEMIS	jz data_phase_dma_loop;	/* ie. underrun */
+data_phase_dma_phasemis:
+		test	SSTAT0,SDONE	jnz data_phase_dma_done;
+		clr	SINDEX;			/* Remember the phasemiss */
+	} else {
+		mov	DMAPARAMS  call dma;
+	}
+
+data_phase_dma_done:
+/* Go tell the host about any overruns */
+	test	SXFRCTL1,BITBUCKET jnz data_phase_overrun;
+
+/* Exit if we had an underrun.  dma clears SINDEX in this case. */
+	test	SINDEX,0xff	jz data_phase_finish;
+
+/*
+ * Advance the scatter-gather pointers if needed 
+ */
+sg_advance:
+	dec	SG_COUNT;	/* one less segment to go */
+
+	test	SG_COUNT, 0xff	jz data_phase_finish; /* Are we done? */
+/*
+ * Load a struct scatter and set up the data address and length.
+ * If the working value of the SG count is nonzero, then
+ * we need to load a new set of values.
+ *
+ * This, like all DMA's, assumes little-endian host data storage.
+ */
+sg_load:
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		/*
+		 * Do we have any prefetch left???
+		 */
+		cmp	CCSGADDR, CCSGADDR_MAX jne prefetched_segs_avail;
+
+		/*
+		 * Fetch MIN(CCSGADDR_MAX, (SG_COUNT * 8)) bytes.
+		 */
+		add	A, -(CCSGRAM_MAXSEGS + 1), SG_COUNT;
+		mvi	A, CCSGADDR_MAX;
+		jc	. + 2;
+		shl	A, 3, SG_COUNT;
+		mov	CCHCNT, A;
+		bmov	CCHADDR, SG_NEXT, 4;
+		mvi	CCSGCTL, CCSGEN|CCSGRESET;
+		test	CCSGCTL, CCSGDONE jz .;
+		and	CCSGCTL, ~CCSGEN;
+		test	CCSGCTL, CCSGEN jnz .;
+		mvi	CCSGCTL, CCSGRESET;
+prefetched_segs_avail:
+		bmov 	HADDR, CCSGRAM, 8;
+		if ((p->features & AHC_ULTRA2) == 0) {
+			bmov    STCNT, HCNT, 3;
+		}
+	} else {
+		mvi	DINDEX, HADDR;
+		mvi	SG_NEXT	call bcopy_4;
+
+		mvi	HCNT[0],SG_SIZEOF;
+		clr	HCNT[1];
+		clr	HCNT[2];
+
+		or	DFCNTRL, HDMAEN|DIRECTION|FIFORESET;
+
+		call	dma_finish;
+
+		/*
+		 * Copy data from FIFO into SCB data pointer and data count.
+		 * This assumes that the SG segments are of the form:
+		 * struct ahc_dma_seg {
+		 *	u_int32_t	addr;	four bytes, little-endian order
+		 *	u_int32_t	len;	four bytes, little endian order
+		 * };
+		 */
+		mvi	HADDR	call dfdat_in_7;
+		call	set_stcnt_from_hcnt;
+	}
+
+/* Advance the SG pointer */
+	clr	A;			/* add sizeof(struct scatter) */
+	add	SG_NEXT[0],SG_SIZEOF;
+	adc	SG_NEXT[1],A;
+
+	test    SSTAT1, REQINIT jz .;
+	test	SSTAT1,PHASEMIS	jz data_phase_loop;
+
+/* This drops the last SG segment down to the shadow layer for us */
+	if ((p->features & AHC_ULTRA2) != 0) {
+		mov	DFCNTRL, DMAPARAMS;
+		test	SSTAT0, SDONE	jnz .;
+	}
+
+data_phase_finish:
+/*
+ * After a DMA finishes, save the SG and STCNT residuals back into the SCB
+ * We use STCNT instead of HCNT, since it's a reflection of how many bytes 
+ * were transferred on the SCSI (as opposed to the host) bus.
+ */
+	if ((p->features & AHC_ULTRA2) != 0) {
+		call	ultra2_dmafinish;
+	}
+	if ((p->features & AHC_ULTRA2) == 0) {
+		if ((p->features & AHC_CMD_CHAN) != 0) {
+			bmov    SCB_RESID_DCNT, STCNT, 3;
+			mov	SCB_RESID_SGCNT, SG_COUNT;
+		} else {
+			mov	SCB_RESID_DCNT[0],STCNT[0];
+			mov	SCB_RESID_DCNT[1],STCNT[1];
+			mov	SCB_RESID_DCNT[2],STCNT[2];
+			mov	SCB_RESID_SGCNT, SG_COUNT;
+		}
+	}
+
+	jmp	ITloop;
+
+data_phase_overrun:
+	if ((p->features & AHC_ULTRA2) != 0) {
+		call	ultra2_dmafinish;
+	}
+/*
+ * Turn off BITBUCKET mode and notify the host
+ */
+	and	SXFRCTL1, ~BITBUCKET;
+	mvi	INTSTAT,DATA_OVERRUN;
+	jmp	ITloop;
+
+ultra2_dmafinish:
+	if ((p->features & AHC_ULTRA2) != 0) {
+		test	DFCNTRL, DIRECTION jnz ultra2_dmahalt;
+		and	DFCNTRL, ~SCSIEN;
+		test	DFCNTRL, SCSIEN jnz .;
+ultra2_dmafifoflush:
+		or	DFCNTRL, FIFOFLUSH;
+		test	DFSTATUS, FIFOEMP jz . - 1;
+		/*
+		 * hardware bug alert!  This needless set of jumps is to
+		 * protect against a FIFOEMP status bit glitch in the
+		 * silicon.
+		 */
+		test	DFSTATUS, FIFOEMP jz ultra2_dmafifoflush;
+		test	DFSTATUS, FIFOEMP jz ultra2_dmafifoflush;
+		test	DFSTATUS, FIFOEMP jz ultra2_dmafifoflush;
+		test	DFSTATUS, FIFOEMP jz ultra2_dmafifoflush;
+		test	DFSTATUS, FIFOEMP jz ultra2_dmafifoflush;
+		test	DFSTATUS, MREQPEND	jnz .;
+ultra2_dmahalt:
+		test	SCSIOFFSET, 0x7f	jnz ultra2_shutdown;
+ultra2_await_nreq:
+		test	SCSISIGI, REQI	jz ultra2_shutdown;
+		test	SSTAT1, (PHASEMIS|REQINIT)	jz ultra2_await_nreq;
+ultra2_shutdown:
+		and     DFCNTRL, ~(HDMAEN|SCSIEN);
+		test	DFCNTRL, (HDMAEN|SCSIEN) jnz .;
+		bmov	SCB_RESID_DCNT, STCNT, 3;
+		mov	SCB_RESID_SGCNT, SG_COUNT;
+		or	SXFRCTL0, CLRSTCNT|CLRCHN;
+		ret;
+	}
+
+/*
+ * Command phase.  Set up the DMA registers and let 'er rip.
+ */
+p_command:
+	call	assert;
+
+/*
+ * Load HADDR and HCNT.
+ */
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		bmov	HADDR, SCB_CMDPTR, 5;
+		bmov	HCNT[1], ALLZEROS, 2;
+		if ((p->features & AHC_ULTRA2) == 0) {
+			bmov	STCNT, HCNT, 3;
+		}
+	} else {
+		mvi	DINDEX, HADDR;
+		mvi	SCB_CMDPTR	call bcopy_5;
+		clr	HCNT[1];
+		clr	HCNT[2];
+		call	set_stcnt_from_hcnt;
+	}
+
+	if ((p->features & AHC_ULTRA2) == 0) {
+		mvi	(SCSIEN|SDMAEN|HDMAEN|DIRECTION|FIFORESET) call dma;
+	} else {
+		mvi	DFCNTRL, (PRELOADEN|SCSIEN|HDMAEN|DIRECTION);
+		test	SSTAT0, SDONE jnz .;
+p_command_dma_loop:
+		test	SSTAT0, SDONE jnz p_command_ultra2_dma_done;
+		test	SSTAT1,PHASEMIS	jz p_command_dma_loop;	/* ie. underrun */
+p_command_ultra2_dma_done:
+		test	SCSISIGI, REQI	jz p_command_ultra2_shutdown;
+		test	SSTAT1, (PHASEMIS|REQINIT)	jz p_command_ultra2_dma_done;
+p_command_ultra2_shutdown:
+		and     DFCNTRL, ~(HDMAEN|SCSIEN);
+		test	DFCNTRL, (HDMAEN|SCSIEN) jnz .;
+		or	SXFRCTL0, CLRSTCNT|CLRCHN;
+	}
+	jmp	ITloop;
+
+/*
+ * Status phase.  Wait for the data byte to appear, then read it
+ * and store it into the SCB.
+ */
+p_status:
+	call	assert;
+
+	mov	SCB_TARGET_STATUS, SCSIDATL;
+	jmp	ITloop;
+
+/*
+ * Message out phase.  If MSG_OUT is 0x80, build I full indentify message
+ * sequence and send it to the target.  In addition, if the MK_MESSAGE bit
+ * is set in the SCB_CONTROL byte, interrupt the host and allow it to send
+ * it's own message.
+ * 
+ * If MSG_OUT is == HOST_MSG, also interrupt the host and take a message.
+ * This is done to allow the hsot to send messages outside of an identify
+ * sequence while protecting the seqencer from testing the MK_MESSAGE bit
+ * on an SCB that might not be for the current nexus. (For example, a
+ * BDR message in responce to a bad reselection would leave us pointed to
+ * an SCB that doesn't have anything to do with the current target).
+ * Otherwise, treat MSG_OUT as a 1 byte message to send (abort, abort tag,
+ * bus device reset).
+ *
+ * When there are no messages to send, MSG_OUT should be set to MSG_NOOP,
+ * in case the target decides to put us in this phase for some strange
+ * reason.
+ */
+p_mesgout_retry:
+	or      SCSISIGO,ATNO,LASTPHASE;/* turn on ATN for the retry */
+p_mesgout:
+	mov	SINDEX, MSG_OUT;
+	cmp	SINDEX, MSG_IDENTIFYFLAG jne p_mesgout_from_host;
+p_mesgout_identify:
+	if ((p->features & AHC_WIDE) != 0) {
+		and	SINDEX,0xf,SCB_TCL;	/* lun */
+	} else {
+		and	SINDEX,0x7,SCB_TCL;	/* lun */
+	}
+	and	A,DISCENB,SCB_CONTROL;	/* mask off disconnect privledge */
+	or	SINDEX,A;		/* or in disconnect privledge */
+	or	SINDEX,MSG_IDENTIFYFLAG;
+p_mesgout_mk_message:
+	test	SCB_CONTROL,MK_MESSAGE  jz p_mesgout_tag;
+	mov	SCSIDATL, SINDEX;	/* Send the last byte */
+	jmp	p_mesgout_from_host + 1;/* Skip HOST_MSG test */
+/*
+ * Send a tag message if TAG_ENB is set in the SCB control block.
+ * Use SCB_TAG (the position in the kernel's SCB array) as the tag value.
+ */
+p_mesgout_tag:
+	test	SCB_CONTROL,TAG_ENB jz  p_mesgout_onebyte;
+	mov	SCSIDATL, SINDEX;	/* Send the identify message */
+	call	phase_lock;
+	cmp	LASTPHASE, P_MESGOUT	jne p_mesgout_done;
+	and	SCSIDATL,TAG_ENB|SCB_TAG_TYPE,SCB_CONTROL;
+	call	phase_lock;
+	cmp	LASTPHASE, P_MESGOUT	jne p_mesgout_done;
+	mov	SCB_TAG	jmp p_mesgout_onebyte;
+/*
+ * Interrupt the driver, and allow it to send a message
+ * if it asks.
+ */
+p_mesgout_from_host:
+	cmp	SINDEX, HOST_MSG	jne p_mesgout_onebyte;
+	mvi     INTSTAT,AWAITING_MSG;
+	nop;
+	/*
+	 * Did the host detect a phase change?
+	 */
+	cmp	RETURN_1, MSGOUT_PHASEMIS je p_mesgout_done;
+
+p_mesgout_onebyte:
+	mvi	CLRSINT1, CLRATNO;
+	mov	SCSIDATL, SINDEX;
+
+/*
+ * If the next bus phase after ATN drops is a message out, it means
+ * that the target is requesting that the last message(s) be resent.
+ */
+	call	phase_lock;
+	cmp     LASTPHASE, P_MESGOUT    je p_mesgout_retry;
+
+p_mesgout_done:
+	mvi	CLRSINT1,CLRATNO;	/* Be sure to turn ATNO off */
+	mov	LAST_MSG, MSG_OUT;
+	cmp	MSG_OUT, MSG_IDENTIFYFLAG jne . + 2;
+	and	SCB_CONTROL, ~MK_MESSAGE;
+	mvi	MSG_OUT, MSG_NOOP;	/* No message left */
+	jmp	ITloop;
+
+/*
+ * Message in phase.  Bytes are read using Automatic PIO mode.
+ */
+p_mesgin:
+	mvi	ACCUM		call inb_first;	/* read the 1st message byte */
+
+	test	A,MSG_IDENTIFYFLAG	jnz mesgin_identify;
+	cmp	A,MSG_DISCONNECT	je mesgin_disconnect;
+	cmp	A,MSG_SAVEDATAPOINTER	je mesgin_sdptrs;
+	cmp	ALLZEROS,A		je mesgin_complete;
+	cmp	A,MSG_RESTOREPOINTERS	je mesgin_rdptrs;
+	cmp	A,MSG_EXTENDED		je mesgin_extended;
+	cmp	A,MSG_MESSAGE_REJECT	je mesgin_reject;
+	cmp	A,MSG_NOOP		je mesgin_done;
+	cmp	A,MSG_IGN_WIDE_RESIDUE	je mesgin_wide_residue;
+
+rej_mesgin:
+/*
+ * We have no idea what this message in is, so we issue a message reject
+ * and hope for the best.  In any case, rejection should be a rare
+ * occurrence - signal the driver when it happens.
+ */
+	mvi	INTSTAT,SEND_REJECT;		/* let driver know */
+
+	mvi	MSG_MESSAGE_REJECT	call mk_mesg;
+
+mesgin_done:
+	mov	NONE,SCSIDATL;		/*dummy read from latch to ACK*/
+	jmp	ITloop;
+
+
+mesgin_complete:
+/*
+ * We got a "command complete" message, so put the SCB_TAG into the QOUTFIFO,
+ * and trigger a completion interrupt.  Before doing so, check to see if there
+ * is a residual or the status byte is something other than STATUS_GOOD (0).
+ * In either of these conditions, we upload the SCB back to the host so it can
+ * process this information.  In the case of a non zero status byte, we 
+ * additionally interrupt the kernel driver synchronously, allowing it to
+ * decide if sense should be retrieved.  If the kernel driver wishes to request
+ * sense, it will fill the kernel SCB with a request sense command and set
+ * RETURN_1 to SEND_SENSE.  If RETURN_1 is set to SEND_SENSE we redownload
+ * the SCB, and process it as the next command by adding it to the waiting list.
+ * If the kernel driver does not wish to request sense, it need only clear
+ * RETURN_1, and the command is allowed to complete normally.  We don't bother
+ * to post to the QOUTFIFO in the error cases since it would require extra
+ * work in the kernel driver to ensure that the entry was removed before the
+ * command complete code tried processing it.
+ */
+
+/*
+ * First check for residuals
+ */
+	test	SCB_RESID_SGCNT,0xff	jnz upload_scb;
+	test	SCB_TARGET_STATUS,0xff	jz complete;	/* Good Status? */
+upload_scb:
+	mvi	DMAPARAMS, FIFORESET;
+	mov	SCB_TAG		call dma_scb;
+check_status:
+	test	SCB_TARGET_STATUS,0xff	jz complete;	/* Just a residual? */
+	mvi	INTSTAT,BAD_STATUS;			/* let driver know */
+	nop;
+	cmp	RETURN_1, SEND_SENSE	jne complete;
+	/* This SCB becomes the next to execute as it will retrieve sense */
+	mvi	DMAPARAMS, HDMAEN|DIRECTION|FIFORESET;
+	mov	SCB_TAG		call dma_scb;
+add_to_waiting_list:
+	mov	SCB_NEXT,WAITING_SCBH;
+	mov	WAITING_SCBH, SCBPTR;
+	/*
+	 * Prepare our selection hardware before the busfree so we have a
+	 * high probability of winning arbitration.
+	 */
+	call	start_selection;
+	jmp	await_busfree;
+
+complete:
+	/* If we are untagged, clear our address up in host ram */
+	test	SCB_CONTROL, TAG_ENB jnz complete_post;
+	mov	A, SAVED_TCL;
+	mvi	UNTAGGEDSCB_OFFSET call post_byte_setup;
+	mvi	SCB_LIST_NULL call post_byte;
+
+complete_post:
+	/* Post the SCB and issue an interrupt */
+	if ((p->features & AHC_QUEUE_REGS) != 0) {
+		mov	A, SDSCB_QOFF;
+	} else {
+		mov	A, QOUTPOS;
+	}
+	mvi	QOUTFIFO_OFFSET call post_byte_setup;
+	mov	SCB_TAG call post_byte;
+	if ((p->features & AHC_QUEUE_REGS) == 0) {
+		inc 	QOUTPOS;
+	}
+	mvi	INTSTAT,CMDCMPLT;
+
+add_to_free_list:
+	call	add_scb_to_free_list;
+	jmp	await_busfree;
+
+/*
+ * Is it an extended message?  Copy the message to our message buffer and
+ * notify the host.  The host will tell us whether to reject this message,
+ * respond to it with the message that the host placed in our message buffer,
+ * or simply to do nothing.
+ */
+mesgin_extended:
+	mvi	INTSTAT,EXTENDED_MSG;		/* let driver know */
+	jmp	ITloop;
+
+/*
+ * Is it a disconnect message?  Set a flag in the SCB to remind us
+ * and await the bus going free.
+ */
+mesgin_disconnect:
+	or	SCB_CONTROL,DISCONNECTED;
+	call	add_scb_to_disc_list;
+	jmp	await_busfree;
+
+/*
+ * Save data pointers message:
+ * Copying RAM values back to SCB, for Save Data Pointers message, but
+ * only if we've actually been into a data phase to change them.  This
+ * protects against bogus data in scratch ram and the residual counts
+ * since they are only initialized when we go into data_in or data_out.
+ */
+mesgin_sdptrs:
+	test	SEQ_FLAGS, DPHASE	jz mesgin_done;
+	/*
+	 * The SCB SGPTR becomes the next one we'll download,
+	 * and the SCB DATAPTR becomes the current SHADDR.
+	 * Use the residual number since STCNT is corrupted by
+	 * any message transfer.
+	 */
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		bmov    SCB_SGCOUNT, SG_COUNT, 5;
+		bmov    SCB_DATAPTR, SHADDR, 4;
+		bmov    SCB_DATACNT, SCB_RESID_DCNT, 3;
+	} else {
+		mvi	DINDEX, SCB_SGCOUNT;
+		mvi	SG_COUNT	call bcopy_5;
+		mvi	DINDEX, SCB_DATAPTR;
+		mvi	SHADDR		call bcopy_4;
+		mvi	SCB_RESID_DCNT	call	bcopy_3;
+	}
+	jmp	mesgin_done;
+
+/*
+ * Restore pointers message?  Data pointers are recopied from the
+ * SCB anytime we enter a data phase for the first time, so all
+ * we need to do is clear the DPHASE flag and let the data phase
+ * code do the rest.
+ */
+mesgin_rdptrs:
+	and	SEQ_FLAGS, ~DPHASE;		/*
+						 * We'll reload them
+						 * the next time through
+						 * the dataphase.
+						 */
+	jmp	mesgin_done;
+
+/*
+ * Identify message?  For a reconnecting target, this tells us the lun
+ * that the reconnection is for - find the correct SCB and switch to it,
+ * clearing the "disconnected" bit so we don't "find" it by accident later.
+ */
+mesgin_identify:
+	
+	if ((p->features & AHC_WIDE) != 0) {
+		and	A,0x0f;		/* lun in lower four bits */
+	} else {
+		and	A,0x07;		/* lun in lower three bits */
+	}
+	or      SAVED_TCL,A;		/* SAVED_TCL should be complete now */
+
+	mvi     ARG_2, SCB_LIST_NULL;   /* SCBID of prev SCB in disc List */
+	call	get_untagged_SCBID;
+	cmp	ARG_1, SCB_LIST_NULL	je snoop_tag;
+	if ((p->flags & AHC_PAGESCBS) != 0) {
+		test	SEQ_FLAGS, SCBPTR_VALID	jz use_retrieveSCB;
+	}
+	/*
+	 * If the SCB was found in the disconnected list (as is
+	 * always the case in non-paging scenarios), SCBPTR is already
+	 * set to the correct SCB.  So, simply setup the SCB and get
+	 * on with things.
+	 */
+	mov	SCBPTR	call rem_scb_from_disc_list;
+	jmp	setup_SCB;
+/*
+ * Here we "snoop" the bus looking for a SIMPLE QUEUE TAG message.
+ * If we get one, we use the tag returned to find the proper
+ * SCB.  With SCB paging, this requires using search for both tagged
+ * and non-tagged transactions since the SCB may exist in any slot.
+ * If we're not using SCB paging, we can use the tag as the direct
+ * index to the SCB.
+ */
+snoop_tag:
+	mov	NONE,SCSIDATL;		/* ACK Identify MSG */
+snoop_tag_loop:
+	call	phase_lock;
+	cmp	LASTPHASE, P_MESGIN	jne not_found;
+	cmp	SCSIBUSL,MSG_SIMPLE_Q_TAG jne not_found;
+get_tag:
+	mvi	ARG_1	call inb_next;	/* tag value */
+
+use_retrieveSCB:
+	call	retrieveSCB;
+setup_SCB:
+	mov	A, SAVED_TCL;
+	cmp	SCB_TCL, A	jne not_found_cleanup_scb;
+	test	SCB_CONTROL,DISCONNECTED jz not_found_cleanup_scb;
+	and	SCB_CONTROL,~DISCONNECTED;
+	or	SEQ_FLAGS,IDENTIFY_SEEN;	  /* make note of IDENTIFY */
+	/* See if the host wants to send a message upon reconnection */
+	test	SCB_CONTROL, MK_MESSAGE jz mesgin_done;
+	and	SCB_CONTROL, ~MK_MESSAGE;
+	mvi	HOST_MSG	call mk_mesg;
+	jmp	mesgin_done;
+
+not_found_cleanup_scb:
+	test	SCB_CONTROL, DISCONNECTED jz . + 3;
+	call	add_scb_to_disc_list;
+	jmp	not_found;
+	call	add_scb_to_free_list;
+not_found:
+	mvi	INTSTAT, NO_MATCH;
+	mvi	MSG_BUS_DEV_RESET	call mk_mesg;
+	jmp	mesgin_done;
+
+/*
+ * Message reject?  Let the kernel driver handle this.  If we have an 
+ * outstanding WDTR or SDTR negotiation, assume that it's a response from 
+ * the target selecting 8bit or asynchronous transfer, otherwise just ignore 
+ * it since we have no clue what it pertains to.
+ */
+mesgin_reject:
+	mvi	INTSTAT, REJECT_MSG;
+	jmp	mesgin_done;
+
+/*
+ * Wide Residue.  We handle the simple cases, but pass of the one hard case
+ * to the kernel (when the residue byte happened to cause us to advance our
+ * sg element array, so we know have to back that advance out).
+ */
+mesgin_wide_residue:
+	mvi	ARG_1	call inb_next; /* ACK the wide_residue and get */
+				       /* the size byte */
+/*
+ * In order for this to be reliable, we have to do all sorts of horrible
+ * magic in terms of resetting the datafifo and reloading the shadow layer
+ * with the correct new values (so that a subsequent save data pointers
+ * message will do the right thing).  We let the kernel do that work.
+ */
+ 	mvi	INTSTAT, WIDE_RESIDUE;
+	jmp	mesgin_done;
+	
+/*
+ * [ ADD MORE MESSAGE HANDLING HERE ]
+ */
+
+/*
+ * Locking the driver out, build a one-byte message passed in SINDEX
+ * if there is no active message already.  SINDEX is returned intact.
+ */
+mk_mesg:
+	or	SCSISIGO,ATNO,LASTPHASE;/* turn on ATNO */
+	mov	MSG_OUT,SINDEX ret;
+
+/*
+ * Functions to read data in Automatic PIO mode.
+ *
+ * According to Adaptec's documentation, an ACK is not sent on input from
+ * the target until SCSIDATL is read from.  So we wait until SCSIDATL is
+ * latched (the usual way), then read the data byte directly off the bus
+ * using SCSIBUSL.  When we have pulled the ATN line, or we just want to
+ * acknowledge the byte, then we do a dummy read from SCISDATL.  The SCSI
+ * spec guarantees that the target will hold the data byte on the bus until
+ * we send our ACK.
+ *
+ * The assumption here is that these are called in a particular sequence,
+ * and that REQ is already set when inb_first is called.  inb_{first,next}
+ * use the same calling convention as inb.
+ */
+
+inb_next:
+	mov	NONE,SCSIDATL;		/*dummy read from latch to ACK*/
+inb_next_wait:
+	/*
+	 * If there is a parity error, wait for the kernel to
+	 * see the interrupt and prepare our message response
+	 * before continuing.
+	 */
+	test	SSTAT1, REQINIT	jz inb_next_wait;
+	test	SSTAT1, SCSIPERR jnz .;
+	and	LASTPHASE, PHASE_MASK, SCSISIGI;
+	cmp	LASTPHASE, P_MESGIN jne mesgin_phasemis;
+inb_first:
+	mov	DINDEX,SINDEX;
+	mov	DINDIR,SCSIBUSL	ret;		/*read byte directly from bus*/
+inb_last:
+	mov	NONE,SCSIDATL ret;		/*dummy read from latch to ACK*/
+
+mesgin_phasemis:
+/*
+ * We expected to receive another byte, but the target changed phase
+ */
+	mvi	INTSTAT, MSGIN_PHASEMIS;
+	jmp	ITloop;
+
+/*
+ * DMA data transfer.  HADDR and HCNT must be loaded first, and
+ * SINDEX should contain the value to load DFCNTRL with - 0x3d for
+ * host->scsi, or 0x39 for scsi->host.  The SCSI channel is cleared
+ * during initialization.
+ */
+if ((p->features & AHC_ULTRA2) == 0) {
+dma:
+	mov	DFCNTRL,SINDEX;
+dma_loop:
+	test	SSTAT0,DMADONE	jnz dma_dmadone;
+	test	SSTAT1,PHASEMIS	jz dma_loop;	/* ie. underrun */
+dma_phasemis:
+	test	SSTAT0,SDONE	jnz dma_checkfifo;
+	mov	SINDEX,ALLZEROS;		/* Notify caller of phasemiss */
+
+/*
+ * We will be "done" DMAing when the transfer count goes to zero, or
+ * the target changes the phase (in light of this, it makes sense that
+ * the DMA circuitry doesn't ACK when PHASEMIS is active).  If we are
+ * doing a SCSI->Host transfer, the data FIFO should be flushed auto-
+ * magically on STCNT=0 or a phase change, so just wait for FIFO empty
+ * status.
+ */
+dma_checkfifo:
+	test	DFCNTRL,DIRECTION	jnz dma_fifoempty;
+dma_fifoflush:
+	test	DFSTATUS,FIFOEMP	jz dma_fifoflush;
+
+dma_fifoempty:
+	/* Don't clobber an inprogress host data transfer */
+	test	DFSTATUS, MREQPEND	jnz dma_fifoempty;
+/*
+ * Now shut the DMA enables off and make sure that the DMA enables are 
+ * actually off first lest we get an ILLSADDR.
+ */
+dma_dmadone:
+	cmp	LASTPHASE, P_COMMAND	je dma_await_nreq;
+	test	SCSIRATE, 0x0f	jnz dma_shutdown;
+dma_await_nreq:
+	test	SCSISIGI, REQI	jz dma_shutdown;
+	test	SSTAT1, (PHASEMIS|REQINIT)	jz dma_await_nreq;
+dma_shutdown:
+	and	DFCNTRL, ~(SCSIEN|SDMAEN|HDMAEN);
+dma_halt:
+	/*
+	 * Some revisions of the aic7880 have a problem where, if the
+	 * data fifo is full, but the PCI input latch is not empty, 
+	 * HDMAEN cannot be cleared.  The fix used here is to attempt
+	 * to drain the data fifo until there is space for the input
+	 * latch to drain and HDMAEN de-asserts.
+	 */
+	mov	NONE, DFDAT;
+	test	DFCNTRL, (SCSIEN|SDMAEN|HDMAEN) jnz dma_halt;
+}
+return:
+	ret;
+
+/*
+ * Assert that if we've been reselected, then we've seen an IDENTIFY
+ * message.
+ */
+assert:
+	test	SEQ_FLAGS,IDENTIFY_SEEN	jnz return;	/* seen IDENTIFY? */
+
+	mvi	INTSTAT,NO_IDENT 	ret;	/* no - tell the kernel */
+
+/*
+ * Locate a disconnected SCB either by SAVED_TCL (ARG_1 is SCB_LIST_NULL)
+ * or by the SCBID ARG_1.  The search begins at the SCB index passed in
+ * via SINDEX which is an SCB that must be on the disconnected list.  If
+ * the SCB cannot be found, SINDEX will be SCB_LIST_NULL, otherwise, SCBPTR
+ * is set to the proper SCB.
+ */
+findSCB:
+	mov	SCBPTR,SINDEX;			/* Initialize SCBPTR */
+	cmp	ARG_1, SCB_LIST_NULL	jne findSCB_by_SCBID;
+	mov	A, SAVED_TCL;
+	mvi	SCB_TCL	jmp findSCB_loop;	/* &SCB_TCL -> SINDEX */
+findSCB_by_SCBID:
+	mov	A, ARG_1;			/* Tag passed in ARG_1 */
+	mvi	SCB_TAG	jmp findSCB_loop;	/* &SCB_TAG -> SINDEX */
+findSCB_next:
+	mov     ARG_2, SCBPTR;
+	cmp	SCB_NEXT, SCB_LIST_NULL je notFound;
+	mov	SCBPTR,SCB_NEXT;
+	dec	SINDEX;		/* Last comparison moved us too far */
+findSCB_loop:
+	cmp	SINDIR, A	jne findSCB_next;
+	mov	SINDEX, SCBPTR 	ret;
+notFound:
+	mvi	SINDEX, SCB_LIST_NULL	ret;
+
+/*
+ * Retrieve an SCB by SCBID first searching the disconnected list falling
+ * back to DMA'ing the SCB down from the host.  This routine assumes that
+ * ARG_1 is the SCBID of interrest and that SINDEX is the position in the
+ * disconnected list to start the search from.  If SINDEX is SCB_LIST_NULL,
+ * we go directly to the host for the SCB.
+ */
+retrieveSCB:
+	test	SEQ_FLAGS, SCBPTR_VALID	jz retrieve_from_host;
+	mov	SCBPTR	call findSCB;	/* Continue the search */
+	cmp	SINDEX, SCB_LIST_NULL	je retrieve_from_host;
+
+/*
+ * This routine expects SINDEX to contain the index of the SCB to be
+ * removed, SCBPTR to be pointing to that SCB, and ARG_2 to be the
+ * SCBID of the SCB just previous to this one in the list or SCB_LIST_NULL
+ * if it is at the head.
+ */
+rem_scb_from_disc_list:
+/* Remove this SCB from the disconnection list */
+	cmp     ARG_2, SCB_LIST_NULL    je rHead;
+	mov	DINDEX, SCB_NEXT;
+	mov	SCBPTR, ARG_2;
+	mov	SCB_NEXT, DINDEX;
+	mov	SCBPTR, SINDEX ret;
+rHead:
+	mov	DISCONNECTED_SCBH,SCB_NEXT ret;
+
+retrieve_from_host:
+/*
+ * We didn't find it.  Pull an SCB and DMA down the one we want.
+ * We should never get here in the non-paging case.
+ */
+	mov	ALLZEROS	call	get_free_or_disc_scb;
+	mvi	DMAPARAMS, HDMAEN|DIRECTION|FIFORESET;
+	/* Jump instead of call as we want to return anyway */
+	mov	ARG_1	jmp dma_scb;
+
+/*
+ * Determine whether a target is using tagged or non-tagged transactions
+ * by first looking for a matching transaction based on the TCL and if
+ * that fails, looking up this device in the host's untagged SCB array.
+ * The TCL to search for is assumed to be in SAVED_TCL.  The value is
+ * returned in ARG_1 (SCB_LIST_NULL for tagged, SCBID for non-tagged).
+ * The SCBPTR_VALID bit is set in SEQ_FLAGS if we found the information
+ * in an SCB instead of having to go to the host.
+ */
+get_untagged_SCBID:
+	cmp	DISCONNECTED_SCBH, SCB_LIST_NULL je get_SCBID_from_host;
+	mvi	ARG_1, SCB_LIST_NULL;
+	mov	DISCONNECTED_SCBH call findSCB;
+	cmp	SINDEX, SCB_LIST_NULL	je get_SCBID_from_host;
+	or	SEQ_FLAGS, SCBPTR_VALID;/* Was in disconnected list */
+	test	SCB_CONTROL, TAG_ENB	jnz . + 2;
+	mov	ARG_1, SCB_TAG	ret;
+	mvi	ARG_1, SCB_LIST_NULL ret;
+
+/*
+ * Fetch a byte from host memory given an index of (A + (256 * SINDEX))
+ * and a base address of SCBID_ADDR.  The byte is returned in RETURN_2.
+ */
+fetch_byte:
+	mov	ARG_2, SINDEX;
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		mvi	DINDEX, CCHADDR;
+		mvi	SCBID_ADDR call set_1byte_addr;
+		mvi	CCHCNT, 1;
+		mvi	CCSGCTL, CCSGEN|CCSGRESET;
+		test	CCSGCTL, CCSGDONE jz .;
+		mvi	CCSGCTL, CCSGRESET;
+		bmov	RETURN_2, CCSGRAM, 1 ret;
+	} else {
+		mvi	DINDEX, HADDR;
+		mvi	SCBID_ADDR call set_1byte_addr;
+		mvi	HCNT[0], 1;
+		clr	HCNT[1];
+		clr	HCNT[2];
+		mvi	DFCNTRL, HDMAEN|DIRECTION|FIFORESET;
+		call	dma_finish;
+		mov	RETURN_2, DFDAT ret;
+	}
+
+/*
+ * Prepare the hardware to post a byte to host memory given an
+ * index of (A + (256 * SINDEX)) and a base address of SCBID_ADDR.
+ */
+post_byte_setup:
+	mov	ARG_2, SINDEX;
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		mvi	DINDEX, CCHADDR;
+		mvi	SCBID_ADDR call	set_1byte_addr;
+		mvi	CCHCNT, 1;
+		mvi	CCSCBCTL, CCSCBRESET ret;
+	} else {
+		mvi	DINDEX, HADDR;
+		mvi	SCBID_ADDR call	set_1byte_addr;
+		mvi	HCNT[0], 1;
+		clr	HCNT[1];
+		clr	HCNT[2];
+		mvi	DFCNTRL, FIFORESET ret;
+	}
+
+post_byte:
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		bmov	CCSCBRAM, SINDEX, 1;
+		or	CCSCBCTL, CCSCBEN|CCSCBRESET;
+		test	CCSCBCTL, CCSCBDONE jz .;
+		clr	CCSCBCTL ret;
+	} else {
+		mov	DFDAT, SINDEX;
+		or	DFCNTRL, HDMAEN|FIFOFLUSH;
+		jmp	dma_finish;
+	}
+
+get_SCBID_from_host:
+	mov	A, SAVED_TCL;
+	mvi	UNTAGGEDSCB_OFFSET call fetch_byte;
+	mov	RETURN_1,  RETURN_2 ret;
+
+phase_lock:     
+	test	SSTAT1, REQINIT jz phase_lock;
+	test	SSTAT1, SCSIPERR jnz phase_lock;
+	and	SCSISIGO, PHASE_MASK, SCSISIGI;
+	and	LASTPHASE, PHASE_MASK, SCSISIGI ret;
+
+if ((p->features & AHC_CMD_CHAN) == 0) {
+set_stcnt_from_hcnt:
+	mov	STCNT[0], HCNT[0];
+	mov	STCNT[1], HCNT[1];
+	mov	STCNT[2], HCNT[2] ret;
+
+bcopy_7:
+	mov	DINDIR, SINDIR;
+	mov	DINDIR, SINDIR;
+bcopy_5:
+	mov	DINDIR, SINDIR;
+bcopy_4:
+	mov	DINDIR, SINDIR;
+bcopy_3:
+	mov	DINDIR, SINDIR;
+	mov	DINDIR, SINDIR;
+	mov	DINDIR, SINDIR ret;
+}
+
+/*
+ * Setup addr assuming that A is an index into
+ * an array of 32byte objects, SINDEX contains
+ * the base address of that array, and DINDEX
+ * contains the base address of the location
+ * to store the indexed address.
+ */
+set_32byte_addr:
+	shr	ARG_2, 3, A;
+	shl	A, 5;
+/*
+ * Setup addr assuming that A + (ARG_1 * 256) is an
+ * index into an array of 1byte objects, SINDEX contains
+ * the base address of that array, and DINDEX contains
+ * the base address of the location to store the computed
+ * address.
+ */
+set_1byte_addr:
+	add	DINDIR, A, SINDIR;
+	mov	A, ARG_2;
+	adc	DINDIR, A, SINDIR;
+	clr	A;
+	adc	DINDIR, A, SINDIR;
+	adc	DINDIR, A, SINDIR ret;
+
+/*
+ * Either post or fetch and SCB from host memory based on the
+ * DIRECTION bit in DMAPARAMS. The host SCB index is in SINDEX.
+ */
+dma_scb:
+	mov	A, SINDEX;
+	if ((p->features & AHC_CMD_CHAN) != 0) {
+		mvi	DINDEX, CCHADDR;
+		mvi	HSCB_ADDR call set_32byte_addr;
+		mov	CCSCBPTR, SCBPTR;
+		mvi	CCHCNT, 32;
+		test	DMAPARAMS, DIRECTION jz dma_scb_tohost;
+		mvi	CCSCBCTL, CCARREN|CCSCBEN|CCSCBDIR|CCSCBRESET;
+		cmp	CCSCBCTL, CCSCBDONE|ARRDONE|CCARREN|CCSCBEN|CCSCBDIR jne .;
+		jmp	dma_scb_finish;
+dma_scb_tohost:
+		if ((p->chip & AHC_CHIPID_MASK) == AHC_AIC7895) {
+			mvi	CCSCBCTL, CCSCBRESET;
+			bmov	CCSCBRAM, SCB_CONTROL, 32;
+			or	CCSCBCTL, CCSCBEN|CCSCBRESET;
+			test	CCSCBCTL, CCSCBDONE jz .;
+		} else {
+			mvi	CCSCBCTL, CCARREN|CCSCBEN|CCSCBRESET;
+			cmp	CCSCBCTL, CCSCBDONE|ARRDONE|CCARREN|CCSCBEN jne .;
+		}
+dma_scb_finish:
+		clr	CCSCBCTL;
+		test	CCSCBCTL, CCARREN|CCSCBEN jnz .;
+		ret;
+	} else {
+		mvi	DINDEX, HADDR;
+		mvi	HSCB_ADDR call set_32byte_addr;
+		mvi	HCNT[0], 32;
+		clr	HCNT[1];
+		clr	HCNT[2];
+		mov	DFCNTRL, DMAPARAMS;
+		test	DMAPARAMS, DIRECTION	jnz dma_scb_fromhost;
+		/* Fill it with the SCB data */
+copy_scb_tofifo:
+		mvi	SINDEX, SCB_CONTROL;
+		add	A, 32, SINDEX;
+copy_scb_tofifo_loop:
+		mov	DFDAT,SINDIR;
+		mov	DFDAT,SINDIR;
+		mov	DFDAT,SINDIR;
+		mov	DFDAT,SINDIR;
+		mov	DFDAT,SINDIR;
+		mov	DFDAT,SINDIR;
+		mov	DFDAT,SINDIR;
+		mov	DFDAT,SINDIR;
+		cmp	SINDEX, A jne copy_scb_tofifo_loop;
+		or	DFCNTRL, HDMAEN|FIFOFLUSH;
+dma_scb_fromhost:
+		call	dma_finish;
+		/* If we were putting the SCB, we are done */
+		test	DMAPARAMS, DIRECTION	jz	return;
+		mvi	SCB_CONTROL  call dfdat_in_7;
+		call	dfdat_in_7_continued;
+		call	dfdat_in_7_continued;
+		jmp	dfdat_in_7_continued;
+dfdat_in_7:
+		mov     DINDEX,SINDEX;
+dfdat_in_7_continued:
+		mov	DINDIR,DFDAT;
+		mov	DINDIR,DFDAT;
+		mov	DINDIR,DFDAT;
+		mov	DINDIR,DFDAT;
+		mov	DINDIR,DFDAT;
+		mov	DINDIR,DFDAT;
+		mov	DINDIR,DFDAT ret;
+	}
+
+
+/*
+ * Wait for DMA from host memory to data FIFO to complete, then disable
+ * DMA and wait for it to acknowledge that it's off.
+ */
+if ((p->features & AHC_CMD_CHAN) == 0) {
+dma_finish:
+	test	DFSTATUS,HDONE	jz dma_finish;
+	/* Turn off DMA */
+	and	DFCNTRL, ~HDMAEN;
+	test	DFCNTRL, HDMAEN jnz .;
+	ret;
+}
+
+add_scb_to_free_list:
+	if ((p->flags & AHC_PAGESCBS) != 0) {
+		mov	SCB_NEXT, FREE_SCBH;
+		mov	FREE_SCBH, SCBPTR;
+	}
+	mvi	SCB_TAG, SCB_LIST_NULL ret;
+
+if ((p->flags & AHC_PAGESCBS) != 0) {
+get_free_or_disc_scb:
+	cmp	FREE_SCBH, SCB_LIST_NULL jne dequeue_free_scb;
+	cmp	DISCONNECTED_SCBH, SCB_LIST_NULL jne dequeue_disc_scb;
+return_error:
+	mvi	SINDEX, SCB_LIST_NULL	ret;
+dequeue_disc_scb:
+	mov	SCBPTR, DISCONNECTED_SCBH;
+dma_up_scb:
+	mvi	DMAPARAMS, FIFORESET;
+	mov	SCB_TAG		call dma_scb;
+unlink_disc_scb:
+	mov	DISCONNECTED_SCBH, SCB_NEXT ret;
+dequeue_free_scb:
+	mov	SCBPTR, FREE_SCBH;
+	mov	FREE_SCBH, SCB_NEXT ret;
+}
+
+add_scb_to_disc_list:
+/*
+ * Link this SCB into the DISCONNECTED list.  This list holds the
+ * candidates for paging out an SCB if one is needed for a new command.
+ * Modifying the disconnected list is a critical(pause dissabled) section.
+ */
+	mov	SCB_NEXT, DISCONNECTED_SCBH;
+	mov	DISCONNECTED_SCBH, SCBPTR ret;
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)