Change the delivery mechanism for incoming target commands. We now

use a 256 entry ring buffer of descriptersfor this purpose.  This allows
the use of a simple 8bit counter in the sequencer code for tracking start
location.

Entries in the ring buffer now contain a "cmd_valid" byte at their tail.
As an entry is serviced, this byte is cleared by the kernel and set by
the sequencer during its dma of a new entry.  Since this byte is the last
portion of the command touched during a dma, the kernel can use this
byte to ensure the command it processes is completely valid.

The new command format requires a fixed sized DMA from the controller
to deliver which allowed for additional simplification of the sequencer
code.  The hack that required 1 SCB slot to be stolen for incoming
command delivery notification is also gone.

4 files changed, 99 insertions, 83 deletions

diff --git a/sys/dev/aic7xxx/aic7xxx.c b/sys/dev/aic7xxx/aic7xxx.c
index 48014ae..f0139b9 100644
--- a/sys/dev/aic7xxx/aic7xxx.c
+++ b/sys/dev/aic7xxx/aic7xxx.c
@@ -36,7 +36,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *      $Id: aic7xxx.c,v 1.8 1998/10/15 18:21:47 gibbs Exp $
+ *      $Id: aic7xxx.c,v 1.9 1998/10/15 23:49:27 gibbs Exp $
  */
 /*
  * A few notes on features of the driver.
@@ -207,7 +207,8 @@ static void	ahc_compile_devinfo(struct ahc_devinfo *devinfo,
 				    u_int target, char channel);
 static u_int	ahc_abort_wscb(struct ahc_softc *ahc, u_int scbpos, u_int prev);
 static void	ahc_done(struct ahc_softc *ahc, struct scb *scbp);
-static void	ahc_handle_target_cmd(struct ahc_softc *ahc);
+static void	ahc_handle_target_cmd(struct ahc_softc *ahc,
+				      struct target_cmd *cmd);
 static void 	ahc_handle_seqint(struct ahc_softc *ahc, u_int intstat);
 static void	ahc_handle_scsiint(struct ahc_softc *ahc, u_int intstat);
 static void	ahc_handle_reqinit(struct ahc_softc *ahc,
@@ -989,12 +990,6 @@ ahc_intr(void *arg)
 			scb_index = ahc->qoutfifo[ahc->qoutfifonext];
 			ahc->qoutfifo[ahc->qoutfifonext++] = SCB_LIST_NULL;
 
-			if (scb_index == TARGET_CMD_CMPLT
-			 && (ahc->flags & AHC_TARGETMODE) != 0) {
-				ahc_handle_target_cmd(ahc);
-				continue;
-			}
-
 			scb = ahc->scb_data->scbarray[scb_index];
 			if (!scb || !(scb->flags & SCB_ACTIVE)) {
 				printf("%s: WARNING no command for scb %d "
@@ -1012,6 +1007,16 @@ ahc_intr(void *arg)
 				ahc_calc_residual(scb);
 			ahc_done(ahc, scb);
 		}
+
+		if ((ahc->flags & AHC_TARGETMODE) != 0) {
+			while (ahc->targetcmds[ahc->tqinfifonext].cmd_valid) {
+				struct target_cmd *cmd;
+
+				cmd = &ahc->targetcmds[ahc->tqinfifonext++];
+				ahc_handle_target_cmd(ahc, cmd);
+				cmd->cmd_valid = 0;
+			}
+		}
 	}
 	if (intstat & BRKADRINT) {
 		/*
@@ -1041,23 +1046,17 @@ ahc_intr(void *arg)
 }
 
 static void
-ahc_handle_target_cmd(struct ahc_softc *ahc)
+ahc_handle_target_cmd(struct ahc_softc *ahc, struct target_cmd *cmd)
 {
 	struct	  tmode_tstate *tstate;
 	struct	  tmode_lstate *lstate;
 	struct	  ccb_accept_tio *atio;
-	struct	  target_cmd *cmd;
 	u_int8_t *byte;
 	int	  initiator;
 	int	  target;
 	int	  lun;
 
-	cmd = &ahc->targetcmds[ahc->next_targetcmd];
-	ahc->next_targetcmd++;
-	if (ahc->next_targetcmd >= ahc->num_targetcmds)
-		ahc->next_targetcmd = 0;
-
-	initiator = cmd->icl >> 4;
+	initiator = cmd->initiator_channel >> 4;
 	target = cmd->targ_id;
 	lun    = (cmd->identify & MSG_IDENTIFY_LUNMASK);
 
@@ -2535,18 +2534,10 @@ ahc_init(struct ahc_softc *ahc)
 	if (ahc->scb_data->maxhscbs < AHC_SCB_MAX) {
 		ahc->flags |= AHC_PAGESCBS;
 		ahc->scb_data->maxscbs = AHC_SCB_MAX;
-		if ((ahc->flags & AHC_TARGETMODE) != 0) {
-			/* Steal one slot for TMODE commands */
-			ahc->scb_data->maxscbs--;
-		}
 		printf("%d/%d SCBs\n", ahc->scb_data->maxhscbs,
 		       ahc->scb_data->maxscbs);
 	} else {
 		ahc->scb_data->maxscbs = ahc->scb_data->maxhscbs;
-		if ((ahc->flags & AHC_TARGETMODE) != 0) {
-			/* Steal one slot for TMODE commands */
-			ahc->scb_data->maxscbs--;
-		}
 		ahc->flags &= ~AHC_PAGESCBS;
 		printf("%d SCBs\n", ahc->scb_data->maxhscbs);
 	}
@@ -2761,9 +2752,10 @@ ahc_init(struct ahc_softc *ahc)
 	if ((ahc->flags & AHC_TARGETMODE) != 0) {
 		size_t array_size;
 
-		ahc->num_targetcmds = 32;
-		array_size = ahc->num_targetcmds * sizeof(struct target_cmd);
-		ahc->targetcmds = malloc(array_size, M_DEVBUF, M_NOWAIT);
+		array_size = AHC_TMODE_CMDS * sizeof(struct target_cmd);
+		ahc->targetcmds = contigmalloc(array_size, M_DEVBUF,
+					       M_NOWAIT, 0ul, 0xffffffff,
+					       PAGE_SIZE, 0x10000);
 
 		if (ahc->targetcmds == NULL) {
 			printf("%s: unable to allocate targetcmd array.  "
@@ -2771,8 +2763,11 @@ ahc_init(struct ahc_softc *ahc)
 			return (-1);
 		}
 
-		bzero(ahc->targetcmds, array_size);
-		ahc_outb(ahc, TMODE_CMDADDR_NEXT, 0);
+		/* All target command blocks start out invalid. */
+		for (i = 0; i < AHC_TMODE_CMDS; i++)
+			ahc->targetcmds[i].cmd_valid = 0;
+		ahc_outb(ahc, KERNEL_TQINPOS, 0);
+		ahc_outb(ahc, TQINPOS, 0);
 	}
 
 	/*
@@ -3811,7 +3806,10 @@ ahc_loadseq(struct ahc_softc *ahc)
 	u_int8_t download_consts[4];
 
 	/* Setup downloadable constant table */
+#if 0
+	/* No downloaded constants are currently defined. */
 	download_consts[TMODE_NUMCMDS] = ahc->num_targetcmds;
+#endif
 
 	cur_patch = patches;
 	downloaded = 0;
@@ -4812,9 +4810,9 @@ ahc_dump_targcmd(struct target_cmd *cmd)
 	u_int8_t *last_byte;
 	int i;
 
-	byte = &cmd->icl;
+	byte = &cmd->initiator_channel;
 	/* Debugging info for received commands */
-	last_byte = &cmd[1].icl;
+	last_byte = &cmd[1].initiator_channel;
 
 	i = 0;
 	while (byte < last_byte) {
diff --git a/sys/dev/aic7xxx/aic7xxx.h b/sys/dev/aic7xxx/aic7xxx.h
index 06f7d4a..560cb3f 100644
--- a/sys/dev/aic7xxx/aic7xxx.h
+++ b/sys/dev/aic7xxx/aic7xxx.h
@@ -34,7 +34,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: aic7xxx.h,v 1.40 1997/02/25 03:05:35 gibbs Exp $
+ *	$Id: aic7xxx.h,v 1.1 1998/09/15 07:24:16 gibbs Exp $
  */
 
 #ifndef _AIC7XXX_H_
@@ -68,6 +68,12 @@
 				 * aic7850 has only 3.
 				 */
 
+#define AHC_TMODE_CMDS	256    /*
+				* Ring Buffer of incoming target commands.
+				* We allocate 256 to simplify the logic
+				* in the sequencer by using the natural
+				* wrap point of an 8bit counter.
+				*/
 
 #if defined(__FreeBSD__)
 extern u_long ahc_unit;
@@ -247,13 +253,17 @@ struct scb_data {
  * Connection desciptor for select-in requests in target mode.
  * The first byte is the connecting target, followed by identify
  * message and optional tag information, terminated by 0xFF.  The
- * remainder is the command to execute.
+ * remainder is the command to execute.  The cmd_valid byte is on
+ * an 8 byte boundary to simplify setting it on aic7880 hardware
+ * which only has limited direct access to the DMA FIFO.
  */
 struct target_cmd {
-	u_int8_t	icl;		/* Really only holds Initiator ID */
-	u_int8_t	targ_id;	/* Target ID we were selected at */
-	u_int8_t	identify;	/* Identify message */
-	u_int8_t	bytes[29];
+	u_int8_t initiator_channel;
+	u_int8_t targ_id;	/* Target ID we were selected at */
+	u_int8_t identify;	/* Identify message */
+	u_int8_t bytes[21];
+	u_int8_t cmd_valid;
+	u_int8_t pad[7];
 };
 
 /*
@@ -462,10 +472,11 @@ struct ahc_softc {
 	int			 unsolicited_ints;
 	pcici_t			 pci_config_id;
 
-	/* Hmmm. */
+	/*
+	 * Target incoming command FIFO.
+	 */
 	struct target_cmd	*targetcmds;
-	int			 next_targetcmd;
-	int			 num_targetcmds;
+	u_int8_t		 tqinfifonext;
 
 	/*
 	 * Incoming and outgoing message handling.
diff --git a/sys/dev/aic7xxx/aic7xxx.reg b/sys/dev/aic7xxx/aic7xxx.reg
index fff2b6f..a6ab963 100644
--- a/sys/dev/aic7xxx/aic7xxx.reg
+++ b/sys/dev/aic7xxx/aic7xxx.reg
@@ -32,7 +32,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: aic7xxx.reg,v 1.4 1997/06/27 19:38:39 gibbs Exp $
+ *	$Id: aic7xxx.reg,v 1.7 1998/09/15 07:24:16 gibbs Exp $
  */
 
 /*
@@ -763,6 +763,16 @@ register DFSTATUS {
 	bit	FIFOEMP		0x01
 }
 
+register DFWADDR {
+	address			0x95
+	access_mode RW
+}
+
+register DFRADDR {
+	address			0x97
+	access_mode RW
+}
+
 register DFDAT {
 	address			0x099
 	access_mode RW
@@ -1255,10 +1265,14 @@ scratch_ram {
 		size		1
 	}
 	/*
-	 * Offset into the command descriptor array for the next
-	 * available desciptor to use.
+	 * Kernel and sequencer offsets into the queue of
+	 * incoming target mode command descriptors.  The
+	 * queue is full when the ((KERNEL_TQINPOS - TQINPOS) == 1)
 	 */
-	TMODE_CMDADDR_NEXT {
+	KERNEL_TQINPOS {
+		size		1
+	}
+	TQINPOS {                
 		size		1
 	}
 	ARG_1 {
@@ -1360,5 +1374,7 @@ const CMD_GROUP5_BYTE_DELTA	11
 
 /*
  * Number of command descriptors in the command descriptor array.
- */
+ * No longer used, but left here as an example for how downloaded
+ * constantants can be defined.
 const TMODE_NUMCMDS	download
+ */
diff --git a/sys/dev/aic7xxx/aic7xxx.seq b/sys/dev/aic7xxx/aic7xxx.seq
index c1ab64d..2a4e92e 100644
--- a/sys/dev/aic7xxx/aic7xxx.seq
+++ b/sys/dev/aic7xxx/aic7xxx.seq
@@ -32,7 +32,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: aic7xxx.seq,v 1.78 1998/09/15 07:24:16 gibbs Exp $
+ *	$Id: aic7xxx.seq,v 1.79 1998/09/21 16:46:13 gibbs Exp $
  */
 
 #include <dev/aic7xxx/aic7xxx.reg>
@@ -234,11 +234,12 @@ select_in:
 
 		/*
 		 * Setup the DMA for sending the identify and
-		 * command information.  We keep a count of the
-		 * number of bytes to send to the host in ARG_2.
+		 * command information.
 		 */
 		or	SEQ_FLAGS, CMDPHASE_PENDING;
-		mov	A, TMODE_CMDADDR_NEXT;
+
+		/* XXX If ring buffer is full, return busy or queue full */
+		mov     A, TQINPOS;
 		if ((ahc->features & AHC_CMD_CHAN) != 0) {
 			mvi	DINDEX, CCHADDR;
 			mvi	TMODE_CMDADDR call set_32byte_addr;
@@ -289,6 +290,7 @@ select_in:
 		 * Our first message must be one of IDENTIFY, ABORT, or
 		 * BUS_DEVICE_RESET.
 		 */
+		/* XXX May need to be more lax here for older initiators... */
 		test	DINDEX, MSG_IDENTIFYFLAG jz more_first_messages;
 		/* Store for host */
 		if ((ahc->features & AHC_CMD_CHAN) != 0) {
@@ -296,7 +298,6 @@ select_in:
 		} else {
 			mov	DFDAT, DINDEX;
 		}
-		mvi	ARG_2, 3;
 
 		/* Remember for disconnection decision */
 		test	DINDEX, MSG_IDENTIFY_DISCFLAG jnz . + 2;
@@ -337,7 +338,6 @@ select_in:
 		} else {
 			mov	DFDAT, DINDEX;
 		}
-		add	ARG_2, 2;
 		jmp	ident_messages_done;
 
 more_first_messages:
@@ -483,17 +483,6 @@ target_busfree:
 		jmp	poll_for_work;
 
 target_cmdphase:
-		/*
-		 * Add one for the terminating byte
-		 * and one for the command code.
-		 */
-		if ((ahc->features & AHC_CMD_CHAN) != 0) {
-			add	CCHCNT, 2, ARG_2;
-		} else {
-			add	HCNT[0], 2, ARG_2;
-			clr	HCNT[1];
-			clr	HCNT[2];
-		}
 		mvi	SCSISIGO, P_COMMAND|BSYO;
 		call	targ_inb;
 		mov	A, DINDEX;
@@ -506,20 +495,16 @@ target_cmdphase:
 
 		/*
 		 * Determine the number of bytes to read
-		 * based on the command group code using an adding
-		 * jump table.  Count is one less than the total
-		 * since we've already fetched the first byte.
+		 * based on the command group code via table lookup.
+		 * We reuse the first 8 bytes of the TARG_SCSIRATE
+		 * BIOS array for this table. Count is one less than
+		 * the total for the command since we've already fetched
+		 * the first byte.
 		 */
 		shr	A, CMD_GROUP_CODE_SHIFT;
 		add	SINDEX, TARG_SCSIRATE, A;
 		mov	A, SINDIR;
 
-		if ((ahc->features & AHC_CMD_CHAN) != 0) {
-			add	CCHCNT, A;
-		} else {
-			add	HCNT[0], A;
-		}
-
 		test	A, 0xFF jz command_phase_done;
 command_loop:
 		or	SXFRCTL0, SPIOEN;
@@ -566,17 +551,28 @@ complete_target_cmd:
 		test	SEQ_FLAGS, TARG_CMD_PENDING	jnz . + 2;
 		mov	SCB_TAG jmp complete_post;
 		if ((ahc->features & AHC_CMD_CHAN) != 0) {
+			/* Set the valid byte */
+			mvi	CCSCBADDR, 24;
+			mov	CCSCBRAM, ALLONES;
+			mvi	CCHCNT, 28;
 			or	CCSCBCTL, CCSCBEN|CCSCBRESET;
 			test	CCSCBCTL, CCSCBDONE jz .;
 			clr	CCSCBCTL;
 		} else {
+			/* Set the valid byte */
+			or	DFCNTRL, FIFORESET;
+			mvi	DFWADDR, 3; /* Third 64bit word or byte 24 */
+			mov	DFDAT, ALLONES;
+			mvi	HCNT[0], 28;
+			clr	HCNT[1];
+			clr	HCNT[2];
 			or	DFCNTRL, HDMAEN|FIFOFLUSH;
 			call	dma_finish;
 		}
-		inc	TMODE_CMDADDR_NEXT;
-		cmp	TMODE_CMDADDR_NEXT, TMODE_NUMCMDS jne . + 2;
-		clr	TMODE_CMDADDR_NEXT;
-		mvi	TARGET_CMD_CMPLT jmp complete_post;
+		inc	TQINPOS;
+		test	SEQ_FLAGS, NO_DISCONNECT jz . + 2;
+		mvi	INTSTAT,TARGET_SYNC_CMD|CMDCMPLT ret;
+		mvi	INTSTAT,CMDCMPLT ret;
 	}
 initiator_select:
 	mvi	SPIOEN call	initialize_channel;
@@ -960,11 +956,7 @@ p_mesgout:
 	mov	SINDEX, MSG_OUT;
 	cmp	SINDEX, MSG_IDENTIFYFLAG jne p_mesgout_from_host;
 p_mesgout_identify:
-	if ((ahc->features & AHC_WIDE) != 0) {
-		and	SINDEX,0xf,SCB_TCL;	/* lun */
-	} else {
-		and	SINDEX,0x7,SCB_TCL;	/* lun */
-	}
+	and	SINDEX,LID,SCB_TCL;	/* lun */
 	and	A,DISCENB,SCB_CONTROL;	/* mask off disconnect privledge */
 	or	SINDEX,A;		/* or in disconnect privledge */
 	or	SINDEX,MSG_IDENTIFYFLAG;
@@ -1122,9 +1114,8 @@ complete_post:
 		inc 	QOUTPOS;
 	}
 	if ((ahc->flags & AHC_TARGETMODE) != 0) {
-		test	SEQ_FLAGS, NO_DISCONNECT jz . + 3;
-		mvi	INTSTAT,TARGET_SYNC_CMD|CMDCMPLT;
-		ret;
+		test	SEQ_FLAGS, NO_DISCONNECT jz . + 2;
+		mvi	INTSTAT,TARGET_SYNC_CMD|CMDCMPLT ret;
 	}
 	mvi	INTSTAT,CMDCMPLT ret;