53c7,8xx.scr

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#undef DEBUG
#undef EVENTS
; NCR 53c810 driver, main script
; Sponsored by 
;	iX Multiuser Multitasking Magazine
;	[e-mail]
;
; Copyright 1993, 1994, 1995 Drew Eckhardt
;      Visionary Computing 
;      (Unix and Linux consulting and custom programming)
;      [e-mail]
;      [phone]
;
; TolerANT and SCSI SCRIPTS are registered trademarks of NCR Corporation.
;
; PRE-ALPHA
;
; For more information, please consult 
;
; NCR 53C810
; PCI-SCSI I/O Processor
; Data Manual
;
; NCR 53C710 
; SCSI I/O Processor
; Programmers Guide
;
; NCR Microelectronics
; 1635 Aeroplaza Drive
; Colorado Springs, CO 80916
; 1+ [phone]
;
; Toll free literature number
; [phone]
;
; IMPORTANT : This code is self modifying due to the limitations of 
;	the NCR53c7,8xx series chips.  Persons debugging this code with
;	the remote debugger should take this into account, and NOT set
;	breakpoints in modified instructions.
;
; Design:
; The NCR53c7,8xx family of SCSI chips are busmasters with an onboard 
; microcontroller using a simple instruction set.   
;
; So, to minimize the effects of interrupt latency, and to maximize 
; throughput, this driver offloads the practical maximum amount 
; of processing to the SCSI chip while still maintaining a common
; structure.
;
; Where tradeoffs were needed between efficiency on the older
; chips and the newer NCR53c800 series, the NCR53c800 series 
; was chosen.
;
; While the NCR53c700 and NCR53c700-66 lacked the facilities to fully
; automate SCSI transfers without host processor intervention, this 
; isn't the case with the NCR53c710 and newer chips which allow 
;
; - reads and writes to the internal registers from within the SCSI
; 	scripts, allowing the SCSI SCRIPTS(tm) code to save processor
; 	state so that multiple threads of execution are possible, and also
; 	provide an ALU for loop control, etc.
; 
; - table indirect addressing for some instructions. This allows 
;	pointers to be located relative to the DSA ((Data Structure
;	Address) register.
;
; These features make it possible to implement a mailbox style interface,
; where the same piece of code is run to handle I/O for multiple threads
; at once minimizing our need to relocate code.  Since the NCR53c700/
; NCR53c800 series have a unique combination of features, making a 
; a standard ingoing/outgoing mailbox system, costly, I've modified it.
;
; - Mailboxes are a mixture of code and data.  This lets us greatly
; 	simplify the NCR53c810 code and do things that would otherwise
;	not be possible.
;
; The saved data pointer is now implemented as follows :
;
; 	Control flow has been architected such that if control reaches
;	munge_save_data_pointer, on a restore pointers message or 
;	reconnection, a jump to the address formerly in the TEMP register
;	will allow the SCSI command to resume execution.
;

;
; Note : the DSA structures must be aligned on 32 bit boundaries,
; since the source and destination of MOVE MEMORY instructions 
; must share the same alignment and this is the alignment of the
; NCR registers.
;

ABSOLUTE dsa_temp_lun = 0		; Patch to lun for current dsa
ABSOLUTE dsa_temp_next = 0		; Patch to dsa next for current dsa
ABSOLUTE dsa_temp_addr_next = 0		; Patch to address of dsa next address 
					; 	for current dsa
ABSOLUTE dsa_temp_sync = 0		; Patch to address of per-target
					;	sync routine
ABSOLUTE dsa_temp_target = 0		; Patch to id for current dsa
ABSOLUTE dsa_temp_addr_saved_pointer = 0; Patch to address of per-command
					; 	saved data pointer
ABSOLUTE dsa_temp_addr_residual = 0	; Patch to address of per-command
					;	current residual code
ABSOLUTE dsa_temp_addr_saved_residual = 0; Patch to address of per-command
					; saved residual code
ABSOLUTE dsa_temp_addr_new_value = 0	; Address of value for JUMP operand
ABSOLUTE dsa_temp_addr_array_value = 0 	; Address to copy to
ABSOLUTE dsa_temp_addr_dsa_value = 0	; Address of this DSA value

;
; Once a device has initiated reselection, we need to compare it 
; against the singly linked list of commands which have disconnected
; and are pending reselection.  These commands are maintained in 
; an unordered singly linked list of DSA structures, through the
; DSA pointers at their 'centers' headed by the reconnect_dsa_head
; pointer.
; 
; To avoid complications in removing commands from the list,
; I minimize the amount of expensive (at eight operations per
; addition @ 500-600ns each) pointer operations which must
; be done in the NCR driver by precomputing them on the 
; host processor during dsa structure generation.
;
; The fixed-up per DSA code knows how to recognize the nexus
; associated with the corresponding SCSI command, and modifies
; the source and destination pointers for the MOVE MEMORY 
; instruction which is executed when reselected_ok is called
; to remove the command from the list.  Similarly, DSA is 
; loaded with the address of the next DSA structure and
; reselected_check_next is called if a failure occurs.
;
; Perhaps more concisely, the net effect of the mess is 
;
; for (dsa = reconnect_dsa_head, dest = &reconnect_dsa_head, 
;     src = NULL; dsa; dest = &dsa->next, dsa = dsa->next) {
; 	src = &dsa->next;
; 	if (target_id == dsa->id && target_lun == dsa->lun) {
; 		*dest = *src;
; 		break;
;         }	
; }
;
; if (!dsa)
;           error (int_err_unexpected_reselect);
; else  
;     longjmp (dsa->jump_resume, 0);
;
; 	

#if (CHIP != 700) && (CHIP != 70066)
; Define DSA structure used for mailboxes
ENTRY dsa_code_template
dsa_code_template:
ENTRY dsa_code_begin
dsa_code_begin:
	MOVE dmode_memory_to_ncr TO DMODE
	MOVE MEMORY 4, dsa_temp_addr_dsa_value, addr_scratch
	MOVE dmode_memory_to_memory TO DMODE
	CALL scratch_to_dsa
	CALL select
; Handle the phase mismatch which may have resulted from the 
; MOVE FROM dsa_msgout if we returned here.  The CLEAR ATN 
; may or may not be necessary, and we should update script_asm.pl
; to handle multiple pieces.
    CLEAR ATN
    CLEAR ACK

; Replace second operand with address of JUMP instruction dest operand
; in schedule table for this DSA.  Becomes dsa_jump_dest in 53c7,8xx.c.
ENTRY dsa_code_fix_jump
dsa_code_fix_jump:
	MOVE MEMORY 4, NOP_insn, 0
	JUMP select_done

; wrong_dsa loads the DSA register with the value of the dsa_next
; field.
;
wrong_dsa:
;		Patch the MOVE MEMORY INSTRUCTION such that 
;		the destination address is the address of the OLD 
;		next pointer.
;
	MOVE MEMORY 4, dsa_temp_addr_next, reselected_ok + 8
	MOVE dmode_memory_to_ncr TO DMODE	
;
; 	Move the _contents_ of the next pointer into the DSA register as 
;	the next I_T_L or I_T_L_Q tupple to check against the established
;	nexus.
;
	MOVE MEMORY 4, dsa_temp_next, addr_scratch
	MOVE dmode_memory_to_memory TO DMODE
	CALL scratch_to_dsa
	JUMP reselected_check_next

ABSOLUTE dsa_save_data_pointer = 0
ENTRY dsa_code_save_data_pointer
dsa_code_save_data_pointer:
    	MOVE dmode_ncr_to_memory TO DMODE
    	MOVE MEMORY 4, addr_temp, dsa_temp_addr_saved_pointer
    	MOVE dmode_memory_to_memory TO DMODE
; HARD CODED : 24 bytes needs to agree with 53c7,8xx.h
    	MOVE MEMORY 24, dsa_temp_addr_residual, dsa_temp_addr_saved_residual
        CLEAR ACK
#ifdef DEBUG
        INT int_debug_saved
#endif
    	RETURN
ABSOLUTE dsa_restore_pointers = 0
ENTRY dsa_code_restore_pointers
dsa_code_restore_pointers:
    	MOVE dmode_memory_to_ncr TO DMODE
    	MOVE MEMORY 4, dsa_temp_addr_saved_pointer, addr_temp
    	MOVE dmode_memory_to_memory TO DMODE
; HARD CODED : 24 bytes needs to agree with 53c7,8xx.h
    	MOVE MEMORY 24, dsa_temp_addr_saved_residual, dsa_temp_addr_residual
        CLEAR ACK
#ifdef DEBUG
        INT int_debug_restored
#endif
    	RETURN

ABSOLUTE dsa_check_reselect = 0
; dsa_check_reselect determines whether or not the current target and
; lun match the current DSA
ENTRY dsa_code_check_reselect
dsa_code_check_reselect:
	MOVE SSID TO SFBR		; SSID contains 3 bit target ID
; FIXME : we need to accommodate bit fielded and binary here for '7xx/'8xx chips
	JUMP REL (wrong_dsa), IF NOT dsa_temp_target, AND MASK 0xf8
;
; Hack - move to scratch first, since SFBR is not writeable
; 	via the CPU and hence a MOVE MEMORY instruction.
;
	MOVE dmode_memory_to_ncr TO DMODE
	MOVE MEMORY 1, reselected_identify, addr_scratch
	MOVE dmode_memory_to_memory TO DMODE
	MOVE SCRATCH0 TO SFBR
; FIXME : we need to accommodate bit fielded and binary here for '7xx/'8xx chips
	JUMP REL (wrong_dsa), IF NOT dsa_temp_lun, AND MASK 0xf8
;		Patch the MOVE MEMORY INSTRUCTION such that
;		the source address is the address of this dsa's
;		next pointer.
	MOVE MEMORY 4, dsa_temp_addr_next, reselected_ok + 4
	CALL reselected_ok
	CALL dsa_temp_sync	
; Release ACK on the IDENTIFY message _after_ we've set the synchronous 
; transfer parameters! 
	CLEAR ACK
; Implicitly restore pointers on reselection, so a RETURN
; will transfer control back to the right spot.
    	CALL REL (dsa_code_restore_pointers)
    	RETURN
ENTRY dsa_zero
dsa_zero:
ENTRY dsa_code_template_end
dsa_code_template_end:

; Perform sanity check for dsa_fields_start == dsa_code_template_end - 
; dsa_zero, puke.

ABSOLUTE dsa_fields_start =  0	; Sanity marker
				; 	pad 48 bytes (fix this RSN)
ABSOLUTE dsa_next = 48		; len 4 Next DSA
 				; del 4 Previous DSA address
ABSOLUTE dsa_cmnd = 56		; len 4 Scsi_Cmnd * for this thread.
ABSOLUTE dsa_select = 60	; len 4 Device ID, Period, Offset for 
			 	;	table indirect select
ABSOLUTE dsa_msgout = 64	; len 8 table indirect move parameter for 
				;       select message
ABSOLUTE dsa_cmdout = 72	; len 8 table indirect move parameter for 
				;	command
ABSOLUTE dsa_dataout = 80	; len 4 code pointer for dataout
ABSOLUTE dsa_datain = 84	; len 4 code pointer for datain
ABSOLUTE dsa_msgin = 88		; len 8 table indirect move for msgin
ABSOLUTE dsa_status = 96 	; len 8 table indirect move for status byte
ABSOLUTE dsa_msgout_other = 104	; len 8 table indirect for normal message out
				; (Synchronous transfer negotiation, etc).
ABSOLUTE dsa_end = 112

ABSOLUTE schedule = 0 		; Array of JUMP dsa_begin or JUMP (next),
				; terminated by a call to JUMP wait_reselect

; Linked lists of DSA structures
ABSOLUTE reconnect_dsa_head = 0	; Link list of DSAs which can reconnect
ABSOLUTE addr_reconnect_dsa_head = 0 ; Address of variable containing
				; address of reconnect_dsa_head

; These select the source and destination of a MOVE MEMORY instruction
ABSOLUTE dmode_memory_to_memory = 0x0
ABSOLUTE dmode_memory_to_ncr = 0x0
ABSOLUTE dmode_ncr_to_memory = 0x0

ABSOLUTE addr_scratch = 0x0
ABSOLUTE addr_temp = 0x0
#endif /* CHIP != 700 && CHIP != 70066 */

; Interrupts - 
; MSB indicates type
; 0	handle error condition
; 1 	handle message 
; 2 	handle normal condition
; 3	debugging interrupt
; 4 	testing interrupt 
; Next byte indicates specific error

; XXX not yet implemented, I'm not sure if I want to - 
; Next byte indicates the routine the error occurred in
; The LSB indicates the specific place the error occurred
 
ABSOLUTE int_err_unexpected_phase = 0x00000000	; Unexpected phase encountered
ABSOLUTE int_err_selected = 0x00010000		; SELECTED (nee RESELECTED)
ABSOLUTE int_err_unexpected_reselect = 0x00020000 
ABSOLUTE int_err_check_condition = 0x00030000	
ABSOLUTE int_err_no_phase = 0x00040000
ABSOLUTE int_msg_wdtr = 0x01000000		; WDTR message received
ABSOLUTE int_msg_sdtr = 0x01010000		; SDTR received
ABSOLUTE int_msg_1 = 0x01020000			; single byte special message
						; received

ABSOLUTE int_norm_select_complete = 0x02000000	; Select complete, reprogram
						; registers.
ABSOLUTE int_norm_reselect_complete = 0x02010000	; Nexus established
ABSOLUTE int_norm_command_complete = 0x02020000 ; Command complete
ABSOLUTE int_norm_disconnected = 0x02030000	; Disconnected 
ABSOLUTE int_norm_aborted =0x02040000		; Aborted *dsa
ABSOLUTE int_norm_reset = 0x02050000		; Generated BUS reset.
ABSOLUTE int_debug_break = 0x03000000		; Break point
#ifdef DEBUG
ABSOLUTE int_debug_scheduled = 0x03010000	; new I/O scheduled 
ABSOLUTE int_debug_idle = 0x03020000		; scheduler is idle
ABSOLUTE int_debug_dsa_loaded = 0x03030000	; dsa reloaded
ABSOLUTE int_debug_reselected = 0x03040000	; NCR reselected
ABSOLUTE int_debug_head = 0x03050000		; issue head overwritten
ABSOLUTE int_debug_disconnected = 0x03060000	; disconnected
ABSOLUTE int_debug_disconnect_msg = 0x03070000	; got message to disconnect
ABSOLUTE int_debug_dsa_schedule = 0x03080000	; in dsa_schedule
ABSOLUTE int_debug_reselect_check = 0x03090000  ; Check for reselection of DSA
ABSOLUTE int_debug_reselected_ok = 0x030a0000 	; Reselection accepted
#endif
ABSOLUTE int_debug_panic = 0x030b0000		; Panic driver
#ifdef DEBUG
ABSOLUTE int_debug_saved = 0x030c0000 		; save/restore pointers
ABSOLUTE int_debug_restored = 0x030d0000
ABSOLUTE int_debug_sync = 0x030e0000		; Sanity check synchronous 
						; parameters. 
ABSOLUTE int_debug_datain = 0x030f0000		; going into data in phase 
						; now.
ABSOLUTE int_debug_check_dsa = 0x03100000	; Sanity check DSA against
						; SDID.
#endif

ABSOLUTE int_test_1 = 0x04000000		; Test 1 complete
ABSOLUTE int_test_2 = 0x04010000		; Test 2 complete
ABSOLUTE int_test_3 = 0x04020000		; Test 3 complete


; These should start with 0x05000000, with low bits incrementing for 
; each one.

#ifdef EVENTS
ABSOLUTE int_EVENT_SELECT = 0
ABSOLUTE int_EVENT_DISCONNECT = 0
ABSOLUTE int_EVENT_RESELECT = 0
ABSOLUTE int_EVENT_COMPLETE = 0
ABSOLUTE int_EVENT_IDLE = 0
ABSOLUTE int_EVENT_SELECT_FAILED = 0
ABSOLUTE int_EVENT_BEFORE_SELECT = 0
ABSOLUTE int_EVENT_RESELECT_FAILED = 0
#endif
						
ABSOLUTE NCR53c7xx_msg_abort = 0	; Pointer to abort message
ABSOLUTE NCR53c7xx_msg_reject = 0       ; Pointer to reject message
ABSOLUTE NCR53c7xx_zero	= 0		; long with zero in it, use for source
ABSOLUTE NCR53c7xx_sink = 0		; long to dump worthless data in
ABSOLUTE NOP_insn = 0			; NOP instruction

; Pointer to message, potentially multi-byte
ABSOLUTE msg_buf = 0

; Pointer to holding area for reselection information
ABSOLUTE reselected_identify = 0
ABSOLUTE reselected_tag = 0

; Request sense command pointer, it's a 6 byte command, should
; be constant for all commands since we always want 16 bytes of 
; sense and we don't need to change any fields as we did under 
; SCSI-I when we actually cared about the LUN field.
;EXTERNAL NCR53c7xx_sense		; Request sense command

#if (CHIP != 700) && (CHIP != 70066)
; dsa_schedule  
; PURPOSE : after a DISCONNECT message has been received, and pointers
;	saved, insert the current DSA structure at the head of the 
; 	disconnected queue and fall through to the scheduler.
;
; CALLS : OK
;
; INPUTS : dsa - current DSA structure, reconnect_dsa_head - list
;	of disconnected commands
;
; MODIFIES : SCRATCH, reconnect_dsa_head
; 
; EXITS : always passes control to schedule

ENTRY dsa_schedule
dsa_schedule:
#if 0
    INT int_debug_dsa_schedule
#endif

;
; Calculate the address of the next pointer within the DSA 
; structure of the command that is currently disconnecting
;
    CALL dsa_to_scratch
    MOVE SCRATCH0 + dsa_next TO SCRATCH0
    MOVE SCRATCH1 + 0 TO SCRATCH1 WITH CARRY
    MOVE SCRATCH2 + 0 TO SCRATCH2 WITH CARRY
    MOVE SCRATCH3 + 0 TO SCRATCH3 WITH CARRY

; Point the next field of this DSA structure at the current disconnected 
; list
    MOVE dmode_ncr_to_memory TO DMODE
    MOVE MEMORY 4, addr_scratch, dsa_schedule_insert + 8
    MOVE dmode_memory_to_memory TO DMODE
dsa_schedule_insert:
    MOVE MEMORY 4, reconnect_dsa_head, 0 

; And update the head pointer.
    CALL dsa_to_scratch
    MOVE dmode_ncr_to_memory TO DMODE	
    MOVE MEMORY 4, addr_scratch, reconnect_dsa_head
    MOVE dmode_memory_to_memory TO DMODE
/* Temporarily, see what happens. */
#ifndef ORIGINAL
    MOVE SCNTL2 & 0x7f TO SCNTL2