# @(#)aha274x.seq 1.28 94/10/04 jda
#
# Adaptec 274x device driver for Linux.
# Copyright (c) 1994 The University of Calgary Department of Computer Science.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
VERSION AHA274X_SEQ_VERSION 1.28
MAXSCB = 4
SCSISEQ = 0x00
SXFRCTL0 = 0x01
SXFRCTL1 = 0x02
SCSISIGI = 0x03
SCSISIGO = 0x03
SCSIRATE = 0x04
SCSIID = 0x05
SCSIDATL = 0x06
STCNT = 0x08
STCNT+0 = 0x08
STCNT+1 = 0x09
STCNT+2 = 0x0a
SSTAT0 = 0x0b
CLRSINT1 = 0x0c
SSTAT1 = 0x0c
SIMODE1 = 0x11
SCSIBUSL = 0x12
SHADDR = 0x14
SELID = 0x19
SBLKCTL = 0x1f
SEQCTL = 0x60
A = 0x64 # == ACCUM
SINDEX = 0x65
DINDEX = 0x66
ALLZEROS = 0x6a
NONE = 0x6a
SINDIR = 0x6c
DINDIR = 0x6d
FUNCTION1 = 0x6e
HADDR = 0x88
HCNT = 0x8c
HCNT+0 = 0x8c
HCNT+1 = 0x8d
HCNT+2 = 0x8e
SCBPTR = 0x90
INTSTAT = 0x91
DFCNTRL = 0x93
DFSTATUS = 0x94
DFDAT = 0x99
QINFIFO = 0x9b
QINCNT = 0x9c
QOUTFIFO = 0x9d
SCSICONF = 0x5a
# The two reserved bytes at SCBARRAY+1[23] are expected to be set to
# zero, and the reserved bit in SCBARRAY+0 is used as an internal flag
# to indicate whether or not to reload scatter-gather parameters after
# a disconnect.
#
SCBARRAY+0 = 0xa0
SCBARRAY+1 = 0xa1
SCBARRAY+2 = 0xa2
SCBARRAY+3 = 0xa3
SCBARRAY+7 = 0xa7
SCBARRAY+11 = 0xab
SCBARRAY+14 = 0xae
SCBARRAY+15 = 0xaf
SCBARRAY+16 = 0xb0
SCBARRAY+17 = 0xb1
SCBARRAY+18 = 0xb2
SCBARRAY+19 = 0xb3
SCBARRAY+20 = 0xb4
SCBARRAY+21 = 0xb5
SCBARRAY+22 = 0xb6
SCBARRAY+23 = 0xb7
SCBARRAY+24 = 0xb8
SCBARRAY+25 = 0xb9
SIGNAL_0 = 0x01 # unknown scsi bus phase
SIGNAL_1 = 0x11 # message reject
SIGNAL_2 = 0x21 # no IDENTIFY after reconnect
SIGNAL_3 = 0x31 # no cmd match for reconnect
SIGNAL_4 = 0x41 # SDTR -> SCSIRATE conversion
# The host adapter card (at least the BIOS) uses 20-2f for SCSI
# device information, 32-33 and 5a-5f as well. Since we don't support
# wide or twin-bus SCSI, 28-2f can be reclaimed. As it turns out, the
# BIOS trashes 20-27 anyway, writing the synchronous negotiation results
# on top of the BIOS values, so we re-use those for our per-target
# scratchspace (actually a value that can be copied directly into
# SCSIRATE). This implies, since we can't get the BIOS config values,
# that all targets will be negotiated with for synchronous transfer.
# NEEDSDTR has one bit per target indicating if an SDTR message is
# needed for that device - this will be set initially, as well as
# after a bus reset condition.
#
# The high bit of DROPATN is set if ATN should be dropped before the ACK
# when outb is called. REJBYTE contains the first byte of a MESSAGE IN
# message, so the driver can report an intelligible error if a message is
# rejected.
#
# RESELECT's high bit is true if we are currently handling a reselect;
# its next-highest bit is true ONLY IF we've seen an IDENTIFY message
# from the reselecting target. If we haven't had IDENTIFY, then we have
# no idea what the lun is, and we can't select the right SCB register
# bank, so force a kernel panic if the target attempts a data in/out or
# command phase instead of corrupting something.
#
# Note that SG_NEXT occupies four bytes.
#
SYNCNEG = 0x20
DISC_DSB_A = 0x32
DROPATN = 0x30
REJBYTE = 0x31
RESELECT = 0x34
MSG_FLAGS = 0x35
MSG_LEN = 0x36
MSG_START+0 = 0x37
MSG_START+1 = 0x38
MSG_START+2 = 0x39
MSG_START+3 = 0x3a
MSG_START+4 = 0x3b
MSG_START+5 = 0x3c
-MSG_START+0 = 0xc9 # 2's complement of MSG_START+0
ARG_1 = 0x4c # sdtr conversion args & return
ARG_2 = 0x4d
RETURN_1 = 0x4c
SIGSTATE = 0x4e # value written to SCSISIGO
NEEDSDTR = 0x4f # send SDTR message, 1 bit/trgt
SG_SIZEOF = 12 # sizeof(struct scatterlist)
SG_NOLOAD = 0x50 # load SG pointer/length?
SG_COUNT = 0x51 # working value of SG count
SG_NEXT = 0x52 # working value of SG pointer
SG_NEXT+0 = 0x52
SG_NEXT+1 = 0x53
SG_NEXT+2 = 0x54
SG_NEXT+3 = 0x55
# Poll QINCNT for work - the lower three bits contain
# the number of entries in the Queue In FIFO.
#
start:
test SCSISIGI,0x4 jnz reselect # BSYI
test QINCNT,0x7 jz start
# We have at least one queued SCB now. Set the SCB pointer
# from the FIFO so we see the right bank of SCB registers,
# then set SCSI options and set the initiator and target
# SCSI IDs.
#
mov SCBPTR,QINFIFO
mov SCBARRAY+1 call initialize
clr SG_NOLOAD
clr RESELECT
# As soon as we get a successful selection, the target should go
# into the message out phase since we have ATN asserted. Prepare
# the message to send, locking out the device driver. If the device
# driver hasn't beaten us with an ABORT or RESET message, then tack
# on a SDTR negotiation if required.
#
# Messages are stored in scratch RAM starting with a flag byte (high bit
# set means active message), one length byte, and then the message itself.
#
mov SCBARRAY+1 call disconnect # disconnect ok?
and SINDEX,0x7,SCBARRAY+1 # lun
or SINDEX,A # return value from disconnect
or SINDEX,0x80 call mk_mesg # IDENTIFY message
mov A,SINDEX
cmp MSG_START+0,A jne !message # did driver beat us?
mvi MSG_START+1 call mk_sdtr # build SDTR message if needed
!message:
# Enable selection phase as an initiator, and do automatic ATN
# after the selection.
#
mvi SCSISEQ,0x48 # ENSELO|ENAUTOATNO
# Wait for successful arbitration. The AIC-7770 documentation says
# that SELINGO indicates successful arbitration, and that it should
# be used to look for SELDO. However, if the sequencer is paused at
# just the right time - a parallel fsck(8) on two drives did it for
# me - then SELINGO can flip back to false before we've seen it. This
# makes the sequencer sit in the arbitration loop forever. This is
# Not Good.
#
# Therefore, I've added a check in the arbitration loop for SELDO
# too. This could arguably be made a critical section by disabling
# pauses, but I don't want to make a potentially infinite loop a CS.
# I suppose you could fold it into the select loop, too, but since
# I've been hunting this bug for four days it's kinda like a trophy.
#
arbitrate:
test SSTAT0,0x40 jnz *select # SELDO
test SSTAT0,0x10 jz arbitrate # SELINGO
# Wait for a successful selection. If the hardware selection
# timer goes off, then the driver gets the interrupt, so we don't
# need to worry about it.
#
select:
test SSTAT0,0x40 jz select # SELDO
jmp *select
# Reselection is being initiated by a target - we've seen the BSY
# line driven active, and we didn't do it! Enable the reselection
# hardware, and wait for it to finish. Make a note that we've been
# reselected, but haven't seen an IDENTIFY message from the target
# yet.
#
reselect:
mvi SCSISEQ,0x10 # ENRSELI
reselect1:
test SSTAT0,0x20 jz reselect1 # SELDI
mov SELID call initialize
mvi RESELECT,0x80 # reselected, no IDENTIFY
# After the [re]selection, make sure that the [re]selection enable
# bit is off. This chip is flaky enough without extra things
# turned on. Also clear the BUSFREE bit in SSTAT1 since we'll be
# using it shortly.
#
*select:
clr SCSISEQ
mvi CLRSINT1,0x8 # CLRBUSFREE
# Main loop for information transfer phases. If BSY is false, then
# we have a bus free condition, expected or not. Otherwise, wait
# for the target to assert REQ before checking MSG, C/D and I/O
# for the bus phase.
#
# We can't simply look at the values of SCSISIGI here (if we want
# to do synchronous data transfer), because the target won't assert
# REQ if it's already sent us some data that we haven't acknowledged
# yet.
#
ITloop:
test SSTAT1,0x8 jnz p_busfree # BUSFREE
test SSTAT1,0x1 jz ITloop # REQINIT
and A,0xe0,SCSISIGI # CDI|IOI|MSGI
cmp ALLZEROS,A je p_dataout
cmp A,0x40 je p_datain
cmp A,0x80 je p_command
cmp A,0xc0 je p_status
cmp A,0xa0 je p_mesgout
cmp A,0xe0 je p_mesgin
mvi INTSTAT,SIGNAL_0 # unknown - signal driver
p_dataout:
mvi 0 call scsisig # !CDO|!IOO|!MSGO
call assert
call sg_load
mvi A,3
mvi DINDEX,HCNT
mvi SCBARRAY+23 call bcopy
mvi A,3
mvi DINDEX,STCNT
mvi SCBARRAY+23 call bcopy
mvi A,4
mvi DINDEX,HADDR
mvi SCBARRAY+19 call bcopy
mvi 0x3d call dma # SCSIEN|SDMAEN|HDMAEN|
# DIRECTION|FIFORESET
# After a DMA finishes, save the final transfer pointer and count
# back into the SCB, in case a device disconnects in the middle of
# a transfer. Use SHADDR and STCNT instead of HADDR and HCNT, since
# it's a reflection of how many bytes were transferred on the SCSI
# (as opposed to the host) bus.
#
mvi A,3
mvi DINDEX,SCBARRAY+23
mvi STCNT call bcopy
mvi A,4
mvi DINDEX,SCBARRAY+19
mvi SHADDR call bcopy
call sg_advance
mov SCBARRAY+18,SG_COUNT # residual S/G count
jmp ITloop
p_datain:
mvi 0x40 call scsisig # !CDO|IOO|!MSGO
call assert
call sg_load
mvi A,3
mvi DINDEX,HCNT
mvi SCBARRAY+23 call bcopy
mvi A,3
mvi DINDEX,STCNT
mvi SCBARRAY+23 call bcopy
mvi A,4
mvi DINDEX,HADDR
mvi SCBARRAY+19 call bcopy
mvi 0x39 call dma # SCSIEN|SDMAEN|HDMAEN|
# !DIRECTION|FIFORESET
mvi A,3
mvi DINDEX,SCBARRAY+23
mvi STCNT call bcopy
mvi A,4
mvi DINDEX,SCBARRAY+19
mvi SHADDR call bcopy
call sg_advance
mov SCBARRAY+18,SG_COUNT # residual S/G count
jmp ITloop
# Command phase. Set up the DMA registers and let 'er rip - the
# two bytes after the SCB SCSI_cmd_length are zeroed by the driver,
# so we can copy those three bytes directly into HCNT.
#
p_command:
mvi 0x80 call scsisig # CDO|!IOO|!MSGO
call assert
mvi A,3
mvi DINDEX,HCNT
mvi SCBARRAY+11 call bcopy
mvi A,3
mvi DINDEX,STCNT
mvi SCBARRAY+11 call bcopy
mvi A,4
mvi DINDEX,HADDR
mvi SCBARRAY+7 call bcopy
mvi 0x3d call dma # SCSIEN|SDMAEN|HDMAEN|
# DIRECTION|FIFORESET
jmp ITloop
# Status phase. Wait for the data byte to appear, then read it
# and store it into the SCB.
#
p_status:
mvi 0xc0 call scsisig # CDO|IOO|!MSGO
mvi SCBARRAY+14 call inb
jmp ITloop
# Message out phase. If there is no active message, but the target
# took us into this phase anyway, build a no-op message and send it.
#
p_mesgout:
mvi 0xa0 call scsisig # CDO|!IOO|MSGO
mvi 0x8 call mk_mesg # build NOP message
# Set up automatic PIO transfer from MSG_START. Bit 3 in
# SXFRCTL0 (SPIOEN) is already on.
#
mvi SINDEX,MSG_START+0
mov DINDEX,MSG_LEN
clr A
# When target asks for a byte, drop ATN if it's the last one in
# the message. Otherwise, keep going until the message is exhausted.
# (We can't use outb for this since it wants the input in SINDEX.)
#
# Keep an eye out for a phase change, in case the target issues
# a MESSAGE REJECT.
#
p_mesgout2:
test SSTAT0,0x2 jz p_mesgout2 # SPIORDY
test SSTAT1,0x10 jnz p_mesgout6 # PHASEMIS
cmp DINDEX,1 jne p_mesgout3 # last byte?
mvi CLRSINT1,0x40 # CLRATNO - drop ATN
# Write a byte to the SCSI bus. The AIC-7770 refuses to automatically
# send ACKs in automatic PIO or DMA mode unless you make sure that the
# "expected" bus phase in SCSISIGO matches the actual bus phase. This
# behaviour is completely undocumented and caused me several days of
# grief.
#
# After plugging in different drives to test with and using a longer
# SCSI cable, I found that I/O in Automatic PIO mode ceased to function,
# especially when transferring >1 byte. It seems to be much more stable
# if STCNT is set to one before the transfer, and SDONE (in SSTAT0) is
# polled for transfer completion - for both output _and_ input. The
# only theory I have is that SPIORDY doesn't drop right away when SCSIDATL
# is accessed (like the documentation says it does), and that on a longer
# cable run, the sequencer code was fast enough to loop back and see
# an SPIORDY that hadn't dropped yet.
#
p_mesgout3:
call one_stcnt
mov SCSIDATL,SINDIR
p_mesgout4:
test SSTAT0,0x4 jz p_mesgout4 # SDONE
dec DINDEX
inc A
cmp MSG_LEN,A jne p_mesgout2
# 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.
#
p_mesgout5:
test SSTAT1,0x8 jnz p_mesgout6 # BUSFREE
test SSTAT1,0x1 jz p_mesgout5 # REQINIT
and A,0xe0,SCSISIGI # CDI|IOI|MSGI
cmp A,0xa0 jne p_mesgout6
mvi 0x10 call scsisig # ATNO - re-assert ATN
jmp ITloop
p_mesgout6:
mvi CLRSINT1,0x40 # CLRATNO - in case of PHASEMIS
clr MSG_FLAGS # no active msg
jmp ITloop
# Message in phase. Bytes are read using Automatic PIO mode, but not
# using inb. This alleviates a race condition, namely that if ATN had
# to be asserted under Automatic PIO mode, it had to beat the SCSI
# circuitry sending an ACK to the target. This showed up under heavy
# loads and really confused things, since ABORT commands wouldn't be
# seen by the drive after an IDENTIFY message in until it had changed
# to a data I/O phase.
#
p_mesgin:
mvi 0xe0 call scsisig # CDO|IOO|MSGO
mvi A call inb_first # read the 1st message byte
mvi REJBYTE,A # save it for the driver
cmp ALLZEROS,A jne p_mesgin1
# We got a "command complete" message, so put the SCB pointer
# into the Queue Out, and trigger a completion interrupt.
#
mov QOUTFIFO,SCBPTR
mvi INTSTAT,0x2 # CMDCMPLT
jmp p_mesgin_done
# Is it an extended message? We only support the synchronous data
# transfer request message, which will probably be in response to
# an SDTR message out from us. If it's not an SDTR, reject it -
# apparently this can be done after any message in byte, according
# to the SCSI-2 spec.
#
# XXX - we should really reject this if we didn't initiate the SDTR
# negotiation; this may cause problems with unusual devices.
#
p_mesgin1:
cmp A,1 jne p_mesgin2 # extended message code?
mvi A call inb_next
cmp A,3 jne p_mesginN # extended mesg length = 3
mvi A call inb_next
cmp A,1 jne p_mesginN # SDTR code
mvi ARG_1 call inb_next # xfer period
mvi ARG_2 call inb_next # REQ/ACK offset
mvi INTSTAT,SIGNAL_4 # call driver to convert
call ndx_sdtr # index sync config for target
mov DINDEX,SINDEX
mov DINDIR,RETURN_1 # save returned value
not A # turn off "need sdtr" flag
and NEEDSDTR,A
# Even though the SCSI-2 specification says that a device responding
# to our SDTR message should honor our parameters for transmitting
# to us, it doesn't seem to work too well in real life. In particular,
# a lot of CD-ROM and tape units don't function: try using the SDTR
# parameters the device sent us for both transmitting and receiving.
#
mov SCSIRATE,RETURN_1
jmp p_mesgin_done
# Is it a disconnect message? Set a flag in the SCB to remind us
# and await the bus going free.
#
p_mesgin2:
cmp A,4 jne p_mesgin3 # disconnect code?
or SCBARRAY+0,0x4 # set "disconnected" bit
jmp p_mesgin_done
# Save data pointers message? Copy working values into the SCB,
# usually in preparation for a disconnect.
#
p_mesgin3:
cmp A,2 jne p_mesgin4 # save data pointers code?
call sg_ram2scb
jmp p_mesgin_done
# Restore pointers message? Data pointers are recopied from the
# SCB anyway at the start of any DMA operation, so the only thing
# to copy is the scatter-gather values.
#
p_mesgin4:
cmp A,3 jne p_mesgin5 # restore pointers code?
call sg_scb2ram
jmp p_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.
#
p_mesgin5:
test A,0x80 jz p_mesgin6 # identify message?
test A,0x78 jnz p_mesginN # !DiscPriv|!LUNTAR|!Reserved
mov A call findSCB # switch to correct SCB
# If a active message is present after calling findSCB, then either it
# or the driver is trying to abort the command. Either way, something
# untoward has happened and we should just leave it alone.
#
test MSG_FLAGS,0x80 jnz p_mesgin_done
xor SCBARRAY+0,0x4 # clear disconnect bit in SCB
mvi RESELECT,0xc0 # make note of IDENTIFY
call sg_scb2ram # implied restore pointers
# required on reselect
jmp p_mesgin_done
# Message reject? If we have an outstanding SDTR negotiation, assume
# that it's a response from the target selecting asynchronous transfer,
# otherwise just ignore it since we have no clue what it pertains to.
#
# XXX - I don't have a device that responds this way. Does this code
# actually work?
#
p_mesgin6:
cmp A,7 jne p_mesgin7 # message reject code?
and FUNCTION1,0x70,SCSIID # outstanding SDTR message?
mov A,FUNCTION1
test NEEDSDTR,A jz p_mesgin_done # no - ignore rejection
call ndx_sdtr # note use of asynch xfer
mov DINDEX,SINDEX
clr DINDIR
not A # turn off "active sdtr" flag
and NEEDSDTR,A
clr SCSIRATE # select asynch xfer
jmp p_mesgin_done
# [ ADD MORE MESSAGE HANDLING HERE ]
#
p_mesgin7:
# We have no idea what this message in is, and there's no way
# to pass it up to the kernel, so we issue a message reject and
# hope for the best. Since we're now using manual PIO mode to
# read in the message, there should no longer be a race condition
# present when we assert ATN. In any case, rejection should be a
# rare occurrence - signal the driver when it happens.
#
p_mesginN:
or SINDEX,0x10,SIGSTATE # turn on ATNO
call scsisig
mvi INTSTAT,SIGNAL_1 # let driver know
mvi 0x7 call mk_mesg # MESSAGE REJECT message
p_mesgin_done:
call inb_last # ack & turn auto PIO back on
jmp ITloop
# Bus free phase. It might be useful to interrupt the device
# driver if we aren't expecting this. For now, make sure that
# ATN isn't being asserted and look for a new command.
#
p_busfree:
mvi CLRSINT1,0x40 # CLRATNO
clr SIGSTATE
jmp start
# Bcopy: number of bytes to transfer should be in A, DINDEX should
# contain the destination address, and SINDEX should contain the
# source address. All input parameters are trashed on return.
#
bcopy:
mov DINDIR,SINDIR
dec A
cmp ALLZEROS,A jne bcopy
ret
# 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:
mvi SEQCTL,0x40 # PAUSEDIS
test MSG_FLAGS,0x80 jnz mk_mesg1 # active message?
mvi MSG_FLAGS,0x80 # if not, there is now
mvi MSG_LEN,1 # length = 1
mov MSG_START+0,SINDEX # 1-byte message
mk_mesg1:
clr SEQCTL # !PAUSEDIS
ret
# Input byte in Automatic PIO mode. The address to store the byte
# in should be in SINDEX. DINDEX will be used by this routine.
#
inb:
test SSTAT0,0x2 jz inb # SPIORDY
mov DINDEX,SINDEX
call one_stcnt # xfer one byte
mov DINDIR,SCSIDATL
inb1:
test SSTAT0,0x4 jz inb1 # SDONE - wait to "finish"
ret
# Carefully read data in Automatic PIO mode. I first tried this using
# Manual PIO mode, but it gave me continual underrun errors, probably
# indicating that I did something wrong, but I feel more secure leaving
# Automatic PIO on all the time.
#
# 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_first:
mov DINDEX,SINDEX
mov DINDIR,SCSIBUSL ret # read byte directly from bus
inb_next:
mov DINDEX,SINDEX # save SINDEX
call one_stcnt # xfer one byte
mov NONE,SCSIDATL # dummy read from latch to ACK
inb_next1:
test SSTAT0,0x4 jz inb_next1 # SDONE
inb_next2:
test SSTAT0,0x2 jz inb_next2 # SPIORDY - wait for next byte
mov DINDIR,SCSIBUSL ret # read byte directly from bus
inb_last:
call one_stcnt # ACK with dummy read
mov NONE,SCSIDATL
inb_last1:
test SSTAT0,0x4 jz inb_last1 # wait for completion
ret
# Output byte in Automatic PIO mode. The byte to output should be
# in SINDEX. If DROPATN's high bit is set, then ATN will be dropped
# before the byte is output.
#
outb:
test SSTAT0,0x2 jz outb # SPIORDY
call one_stcnt # xfer one byte
test DROPATN,0x80 jz outb1
mvi CLRSINT1,0x40 # CLRATNO
clr DROPATN
outb1:
mov SCSIDATL,SINDEX
outb2:
test SSTAT0,0x4 jz outb2 # SDONE
ret
# Write the value "1" into the STCNT registers, for Automatic PIO
# transfers.
#
one_stcnt:
clr STCNT+2
clr STCNT+1
mvi STCNT+0,1 ret
# 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.
#
dma:
mov DFCNTRL,SINDEX
dma1:
dma2:
test SSTAT0,0x1 jnz dma3 # DMADONE
test SSTAT1,0x10 jz dma1 # PHASEMIS, ie. underrun
# 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, flush the data FIFO.
#
dma3:
test SINDEX,0x4 jnz dma5 # DIRECTION
and SINDEX,0xfe # mask out FIFORESET
or DFCNTRL,0x2,SINDEX # FIFOFLUSH
dma4:
test DFCNTRL,0x2 jnz dma4 # FIFOFLUSHACK
# Now shut the DMA enables off, and copy STCNT (ie. the underrun
# amount, if any) to the SCB registers; SG_COUNT will get copied to
# the SCB's residual S/G count field after sg_advance is called. Make
# sure that the DMA enables are actually off first lest we get an ILLSADDR.
#
dma5:
clr DFCNTRL # disable DMA
dma6:
test DFCNTRL,0x38 jnz dma6 # SCSIENACK|SDMAENACK|HDMAENACK
mvi A,3
mvi DINDEX,SCBARRAY+15
mvi STCNT call bcopy
ret
# Common SCSI initialization for selection and reselection. Expects
# the target SCSI ID to be in the upper four bits of SINDEX, and A's
# contents are stomped on return.
#
initialize:
clr SBLKCTL # channel A, !wide
and SCSIID,0xf0,SINDEX # target ID
and A,0x7,SCSICONF # SCSI_ID_A[210]
or SCSIID,A
# Esundry initialization.
#
clr DROPATN
clr SIGSTATE
# Turn on Automatic PIO mode now, before we expect to see an REQ
# from the target. It shouldn't hurt anything to leave it on. Set
# CLRCHN here before the target has entered a data transfer mode -
# with synchronous SCSI, if you do it later, you blow away some
# data in the SCSI FIFO that the target has already sent to you.
#
mvi SXFRCTL0,0xa # SPIOEN|CLRCHN
# Set SCSI bus parity checking and the selection timeout value,
# and enable the hardware selection timer. Set the SELTO interrupt
# to signal the driver.
#
and A,0x38,SCSICONF # PARITY_ENB_A|SEL_TIM_A[10]
or SXFRCTL1,0x4,A # ENSTIMER
mvi SIMODE1,0x84 # ENSELTIMO|ENSCSIPERR
# Initialize scatter-gather pointers by setting up the working copy
# in scratch RAM.
#
call sg_scb2ram
# Initialize SCSIRATE with the appropriate value for this target.
#
call ndx_sdtr
mov SCSIRATE,SINDIR
ret
# Assert that if we've been reselected, then we've seen an IDENTIFY
# message.
#
assert:
test RESELECT,0x80 jz assert1 # reselected?
test RESELECT,0x40 jnz assert1 # seen IDENTIFY?
mvi INTSTAT,SIGNAL_2 # no - cause a kernel panic
assert1:
ret
# Find out if disconnection is ok from the information the BIOS has left
# us. The target ID should be in the upper four bits of SINDEX; A will
# contain either 0x40 (disconnection ok) or 0x00 (disconnection not ok)
# on exit.
#
# This is the only place the target ID is limited to three bits, so we
# can use the FUNCTION1 register.
#
disconnect:
and FUNCTION1,0x70,SINDEX # strip off extra just in case
mov A,FUNCTION1
test DISC_DSB_A,A jz disconnect1 # bit nonzero if DISabled
clr A ret
disconnect1:
mvi A,0x40 ret
# Locate the SCB matching the target ID in SELID and the lun in the lower
# three bits of SINDEX, and switch the SCB to it. Have the kernel print
# a warning message if it can't be found - this seems to happen occasionally
# under high loads. Also, if not found, generate an ABORT message to the
# target.
#
findSCB:
and A,0x7,SINDEX # lun in lower three bits
or A,A,SELID # can I do this?
and A,0xf7 # only channel A implemented
clr SINDEX
findSCB1:
mov SCBPTR,SINDEX # switch to new SCB
cmp SCBARRAY+1,A jne findSCB2 # target ID/channel/lun match?
test SCBARRAY+0,0x4 jz findSCB2 # should be disconnected
ret
findSCB2:
inc SINDEX
cmp SINDEX,MAXSCB jne findSCB1
mvi INTSTAT,SIGNAL_3 # not found - signal kernel
mvi 0x6 call mk_mesg # ABORT message
or SINDEX,0x10,SIGSTATE # assert ATNO
call scsisig
ret
# Make a working copy of the scatter-gather parameters in the SCB.
#
sg_scb2ram:
mov SG_COUNT,SCBARRAY+2
mvi A,4
mvi DINDEX,SG_NEXT
mvi SCBARRAY+3 call bcopy
mvi SG_NOLOAD,0x80
test SCBARRAY+0,0x10 jnz sg_scb2ram1 # don't reload s/g?
clr SG_NOLOAD
sg_scb2ram1:
ret
# Copying RAM values back to SCB, for Save Data Pointers message.
#
sg_ram2scb:
mov SCBARRAY+2,SG_COUNT
mvi A,4
mvi DINDEX,SCBARRAY+3
mvi SG_NEXT call bcopy
and SCBARRAY+0,0xef,SCBARRAY+0
test SG_NOLOAD,0x80 jz sg_ram2scb1 # reload s/g?
or SCBARRAY+0,0x10
sg_ram2scb1:
ret
# Load a struct scatter if needed 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 the above DMA, assumes a little-endian host data storage.
#
sg_load:
test SG_COUNT,0xff jz sg_load3 # SG being used?
test SG_NOLOAD,0x80 jnz sg_load3 # don't reload s/g?
clr HCNT+2
clr HCNT+1
mvi HCNT+0,SG_SIZEOF
mvi A,4
mvi DINDEX,HADDR
mvi SG_NEXT call bcopy
mvi DFCNTRL,0xd # HDMAEN|DIRECTION|FIFORESET
# Wait for DMA from host memory to data FIFO to complete, then disable
# DMA and wait for it to acknowledge that it's off.
#
sg_load1:
test DFSTATUS,0x8 jz sg_load1 # HDONE
clr DFCNTRL # disable DMA
sg_load2:
test DFCNTRL,0x8 jnz sg_load2 # HDMAENACK
# Copy data from FIFO into SCB data pointer and data count. This assumes
# that the struct scatterlist has this structure (this and sizeof(struct
# scatterlist) == 12 are asserted in aha274x.c):
#
# struct scatterlist {
# char *address; /* four bytes, little-endian order */
# ... /* four bytes, ignored */
# unsigned short length; /* two bytes, little-endian order */
# }
#
mov SCBARRAY+19,DFDAT # new data address
mov SCBARRAY+20,DFDAT
mov SCBARRAY+21,DFDAT
mov SCBARRAY+22,DFDAT
mov NONE,DFDAT # throw away four bytes
mov NONE,DFDAT
mov NONE,DFDAT
mov NONE,DFDAT
mov SCBARRAY+23,DFDAT
mov SCBARRAY+24,DFDAT
clr SCBARRAY+25
sg_load3:
ret
# Advance the scatter-gather pointers only IF NEEDED. If SG is enabled,
# and the SCSI transfer count is zero (note that this should be called
# right after a DMA finishes), then move the working copies of the SG
# pointer/length along. If the SCSI transfer count is not zero, then
# presumably the target is disconnecting - do not reload the SG values
# next time.
#
sg_advance:
test SG_COUNT,0xff jz sg_advance2 # s/g enabled?
test STCNT+0,0xff jnz sg_advance1 # SCSI transfer count nonzero?
test STCNT+1,0xff jnz sg_advance1
test STCNT+2,0xff jnz sg_advance1
clr SG_NOLOAD # reload s/g next time
dec SG_COUNT # one less segment to go
clr A # add sizeof(struct scatter)
add SG_NEXT+0,SG_SIZEOF,SG_NEXT+0
adc SG_NEXT+1,A,SG_NEXT+1
adc SG_NEXT+2,A,SG_NEXT+2
adc SG_NEXT+3,A,SG_NEXT+3
ret
sg_advance1:
mvi SG_NOLOAD,0x80 # don't reload s/g next time
sg_advance2:
ret
# Add the array base SYNCNEG to the target offset (the target address
# is in SCSIID), and return the result in SINDEX. The accumulator
# contains the 3->8 decoding of the target ID on return.
#
ndx_sdtr:
shr A,SCSIID,4
and A,0x7
add SINDEX,SYNCNEG,A
and FUNCTION1,0x70,SCSIID # 3-bit target address decode
mov A,FUNCTION1 ret
# If we need to negotiate transfer parameters, build the SDTR message
# starting at the address passed in SINDEX. DINDEX is modified on return.
#
mk_sdtr:
mov DINDEX,SINDEX # save SINDEX
call ndx_sdtr
test NEEDSDTR,A jnz mk_sdtr1 # do we need negotiation?
ret
mk_sdtr1:
mvi DINDIR,1 # extended message
mvi DINDIR,3 # extended message length = 3
mvi DINDIR,1 # SDTR code
mvi DINDIR,25 # REQ/ACK transfer period
mvi DINDIR,15 # REQ/ACK offset
add MSG_LEN,-MSG_START+0,DINDEX # update message length
ret
# Set SCSI bus control signal state. This also saves the last-written
# value into a location where the higher-level driver can read it - if
# it has to send an ABORT or RESET message, then it needs to know this
# so it can assert ATN without upsetting SCSISIGO. The new value is
# expected in SINDEX. Change the actual state last to avoid contention
# from the driver.
#
scsisig:
mov SIGSTATE,SINDEX
mov SCSISIGO,SINDEX ret
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