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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:04 EST.

1	The Linux NCR53C8XX/SYM53C8XX drivers README file
2	
3	Written by Gerard Roudier <groudier@free.fr>
4	21 Rue Carnot
5	95170 DEUIL LA BARRE - FRANCE
6	
7	29 May 1999
8	===============================================================================
9	
10	1.  Introduction
11	2.  Supported chips and SCSI features
12	3.  Advantages of the enhanced 896 driver
13	      3.1 Optimized SCSI SCRIPTS
14	      3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
15	4.  Memory mapped I/O versus normal I/O
16	5.  Tagged command queueing
17	6.  Parity checking
18	7.  Profiling information
19	8.  Control commands
20	      8.1  Set minimum synchronous period
21	      8.2  Set wide size
22	      8.3  Set maximum number of concurrent tagged commands
23	      8.4  Set order type for tagged command
24	      8.5  Set debug mode
25	      8.6  Clear profile counters
26	      8.7  Set flag (no_disc)
27	      8.8  Set verbose level
28	      8.9  Reset all logical units of a target
29	      8.10 Abort all tasks of all logical units of a target
30	9.  Configuration parameters
31	10. Boot setup commands
32	      10.1 Syntax
33	      10.2 Available arguments
34	             10.2.1  Master parity checking
35	             10.2.2  Scsi parity checking
36	             10.2.3  Scsi disconnections
37	             10.2.4  Special features
38	             10.2.5  Ultra SCSI support
39	             10.2.6  Default number of tagged commands
40	             10.2.7  Default synchronous period factor
41	             10.2.8  Negotiate synchronous with all devices
42	             10.2.9  Verbosity level
43	             10.2.10 Debug mode
44	             10.2.11 Burst max
45	             10.2.12 LED support
46	             10.2.13 Max wide
47	             10.2.14 Differential mode
48	             10.2.15 IRQ mode
49	             10.2.16 Reverse probe
50	             10.2.17 Fix up PCI configuration space
51	             10.2.18 Serial NVRAM
52	             10.2.19 Check SCSI BUS 
53	             10.2.20 Exclude a host from being attached
54	             10.2.21 Suggest a default SCSI id for hosts
55	             10.2.22 Enable use of IMMEDIATE ARBITRATION
56	      10.3 Advised boot setup commands
57	      10.4 PCI configuration fix-up boot option
58	      10.5 Serial NVRAM support boot option
59	      10.6 SCSI BUS checking boot option
60	      10.7 IMMEDIATE ARBITRATION boot option
61	11. Some constants and flags of the ncr53c8xx.h header file
62	12. Installation
63	13. Architecture dependent features
64	14. Known problems
65	      14.1 Tagged commands with Iomega Jaz device
66	      14.2 Device names change when another controller is added
67	      14.3 Using only 8 bit devices with a WIDE SCSI controller.
68	      14.4 Possible data corruption during a Memory Write and Invalidate
69	      14.5 IRQ sharing problems
70	15. SCSI problem troubleshooting
71	      15.1 Problem tracking
72	      15.2 Understanding hardware error reports
73	16. Synchronous transfer negotiation tables
74	      16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers
75	      16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
76	17. Serial NVRAM support (by Richard Waltham)
77	      17.1 Features
78	      17.2 Symbios NVRAM layout
79	      17.3 Tekram  NVRAM layout
80	18. Support for Big Endian
81	      18.1 Big Endian CPU
82	      18.2 NCR chip in Big Endian mode of operations
83	
84	===============================================================================
85	
86	1. Introduction
87	
88	The initial Linux ncr53c8xx driver has been a port of the ncr driver from 
89	FreeBSD that has been achieved in November 1995 by:
90	          Gerard Roudier              <groudier@free.fr>
91	
92	The original driver has been written for 386bsd and FreeBSD by:
93	          Wolfgang Stanglmeier        <wolf@cologne.de>
94	          Stefan Esser                <se@mi.Uni-Koeln.de>
95	
96	It is now available as a bundle of 2 drivers:
97	
98	- ncr53c8xx generic driver that supports all the SYM53C8XX family including 
99	  the earliest 810 rev. 1, the latest 896 (2 channel LVD SCSI controller) and
100	  the new 895A (1 channel LVD SCSI controller).
101	- sym53c8xx enhanced driver (a.k.a. 896 drivers) that drops support of oldest 
102	  chips in order to gain advantage of new features, as LOAD/STORE instructions 
103	  available since the 810A and hardware phase mismatch available with the 
104	  896 and the 895A.
105	
106	You can find technical information about the NCR 8xx family in the
107	PCI-HOWTO written by Michael Will and in the SCSI-HOWTO written by
108	Drew Eckhardt.
109	
110	Information about new chips is available at LSILOGIC web server:
111	
112	          http://www.lsilogic.com/
113	
114	SCSI standard documentations are available at SYMBIOS ftp server:
115	
116	          ftp://ftp.symbios.com/
117	
118	Useful SCSI tools written by Eric Youngdale are available at tsx-11:
119	
120	          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsiinfo-X.Y.tar.gz
121	          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsidev-X.Y.tar.gz
122	
123	These tools are not ALPHA but quite clean and work quite well.
124	It is essential you have the 'scsiinfo' package.
125	
126	This short documentation describes the features of the generic and enhanced
127	drivers, configuration parameters and control commands available through 
128	the proc SCSI file system read / write operations.
129	
130	This driver has been tested OK with linux/i386, Linux/Alpha and Linux/PPC.
131	
132	Latest driver version and patches are available at:
133	
134	          ftp://ftp.tux.org/pub/people/gerard-roudier
135	or
136	          ftp://ftp.symbios.com/mirror/ftp.tux.org/pub/tux/roudier/drivers
137	
138	I am not a native speaker of English and there are probably lots of
139	mistakes in this README file. Any help will be welcome.
140	
141	
142	2. Supported chips and SCSI features
143	
144	The following features are supported for all chips:
145	
146		Synchronous negotiation
147		Disconnection
148		Tagged command queuing
149		SCSI parity checking
150		Master parity checking
151	
152	"Wide negotiation" is supported for chips that allow it.  The
153	following table shows some characteristics of NCR 8xx family chips 
154	and what drivers support them.
155	
156	                                                  Supported by   Supported by
157	       On board                                   the generic    the enhanced 
158	Chip   SDMS BIOS   Wide   SCSI std.   Max. sync   driver         driver
159	----   ---------   ----   ---------   ----------  ------------   -------------
160	810        N         N      FAST10    10 MB/s        Y             N
161	810A       N         N      FAST10    10 MB/s        Y             Y
162	815        Y         N      FAST10    10 MB/s        Y             N
163	825        Y         Y      FAST10    20 MB/s        Y             N
164	825A       Y         Y      FAST10    20 MB/s        Y             Y
165	860        N         N      FAST20    20 MB/s        Y             Y
166	875        Y         Y      FAST20    40 MB/s        Y             Y
167	876        Y         Y      FAST20    40 MB/s        Y             Y
168	895        Y         Y      FAST40    80 MB/s        Y             Y
169	895A       Y         Y      FAST40    80 MB/s        Y             Y
170	896        Y         Y      FAST40    80 MB/s        Y             Y
171	897        Y         Y      FAST40    80 MB/s        Y             Y
172	1510D      Y         Y      FAST40    80 MB/s        Y             Y
173	1010       Y         Y      FAST80   160 MB/s        N             Y
174	1010_66*   Y         Y      FAST80   160 MB/s        N             Y
175	
176	* Chip supports 33MHz and 66MHz PCI buses.
177	
178	
179	Summary of other supported features:
180	
181	Module:                allow to load the driver
182	Memory mapped I/O:     increases performance
183	Profiling information: read operations from the proc SCSI file system
184	Control commands:      write operations to the proc SCSI file system
185	Debugging information: written to syslog (expert only)
186	Scatter / gather
187	Shared interrupt
188	Boot setup commands
189	Serial NVRAM:          Symbios and Tekram formats
190	
191	
192	3. Advantages of the enhanced 896 driver
193	
194	3.1 Optimized SCSI SCRIPTS.
195	
196	The 810A, 825A, 875, 895, 896 and 895A support new SCSI SCRIPTS instructions 
197	named LOAD and STORE that allow to move up to 1 DWORD from/to an IO register 
198	to/from memory much faster that the MOVE MEMORY instruction that is supported 
199	by the 53c7xx and 53c8xx family.
200	The LOAD/STORE instructions support absolute and DSA relative addressing 
201	modes.  The SCSI SCRIPTS had been entirely rewritten using LOAD/STORE instead 
202	of MOVE MEMORY instructions.
203	
204	3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
205	
206	The 896 and the 895A allows handling of the phase mismatch context from 
207	SCRIPTS (avoids the phase mismatch interrupt that stops the SCSI processor 
208	until the C code has saved the context of the transfer).
209	Implementing this without using LOAD/STORE instructions would be painful 
210	and I didn't even want to try it.
211	
212	The 896 chip supports 64 bit PCI transactions and addressing, while the 
213	895A supports 32 bit PCI transactions and 64 bit addressing.
214	The SCRIPTS processor of these chips is not true 64 bit, but uses segment 
215	registers for bit 32-63. Another interesting feature is that LOAD/STORE 
216	instructions that address the on-chip RAM (8k) remain internal to the chip.
217	
218	Due to the use of LOAD/STORE SCRIPTS instructions, this driver does not 
219	support the following chips:
220	- SYM53C810 revision < 0x10 (16)
221	- SYM53C815 all revisions
222	- SYM53C825 revision < 0x10 (16)
223	
224	4. Memory mapped I/O versus normal I/O
225	
226	Memory mapped I/O has less latency than normal I/O.  Since
227	linux-1.3.x, memory mapped I/O is used rather than normal I/O.  Memory
228	mapped I/O seems to work fine on most hardware configurations, but
229	some poorly designed motherboards may break this feature.
230	
231	The configuration option CONFIG_SCSI_NCR53C8XX_IOMAPPED forces the
232	driver to use normal I/O in all cases.
233	
234	
235	5. Tagged command queueing
236	
237	Queuing more than 1 command at a time to a device allows it to perform 
238	optimizations based on actual head positions and its mechanical 
239	characteristics. This feature may also reduce average command latency.
240	In order to really gain advantage of this feature, devices must have 
241	a reasonable cache size (No miracle is to be expected for a low-end 
242	hard disk with 128 KB or less).
243	Some known SCSI devices do not properly support tagged command queuing.
244	Generally, firmware revisions that fix this kind of problems are available 
245	at respective vendor web/ftp sites.
246	All I can say is that the hard disks I use on my machines behave well with 
247	this driver with tagged command queuing enabled:
248	
249	- IBM S12 0662
250	- Conner 1080S
251	- Quantum Atlas I
252	- Quantum Atlas II
253	
254	If your controller has NVRAM, you can configure this feature per target 
255	from the user setup tool. The Tekram Setup program allows to tune the 
256	maximum number of queued commands up to 32. The Symbios Setup only allows 
257	to enable or disable this feature.
258	
259	The maximum number of simultaneous tagged commands queued to a device
260	is currently set to 8 by default.  This value is suitable for most SCSI
261	disks.  With large SCSI disks (>= 2GB, cache >= 512KB, average seek time
262	<= 10 ms), using a larger value may give better performances.
263	
264	The sym53c8xx driver supports up to 255 commands per device, and the 
265	generic ncr53c8xx driver supports up to 64, but using more than 32 is 
266	generally not worth-while, unless you are using a very large disk or disk 
267	array. It is noticeable that most of recent hard disks seem not to accept 
268	more than 64 simultaneous commands. So, using more than 64 queued commands 
269	is probably just resource wasting.
270	
271	If your controller does not have NVRAM or if it is managed by the SDMS 
272	BIOS/SETUP, you can configure tagged queueing feature and device queue 
273	depths from the boot command-line. For example:
274	
275	  ncr53c8xx=tags:4/t2t3q15-t4q7/t1u0q32
276	
277	will set tagged commands queue depths as follow:
278	
279	- target 2  all luns  on controller 0 --> 15
280	- target 3  all luns  on controller 0 --> 15
281	- target 4  all luns  on controller 0 -->  7
282	- target 1  lun 0     on controller 1 --> 32
283	- all other target/lun                -->  4
284	
285	In some special conditions, some SCSI disk firmwares may return a
286	QUEUE FULL status for a SCSI command. This behaviour is managed by the
287	driver using the following heuristic:
288	
289	- Each time a QUEUE FULL status is returned, tagged queue depth is reduced 
290	  to the actual number of disconnected commands. 
291	
292	- Every 1000 successfully completed SCSI commands, if allowed by the
293	  current limit, the maximum number of queueable commands is incremented.
294	
295	Since QUEUE FULL status reception and handling is resource wasting, the 
296	driver notifies by default this problem to user by indicating the actual 
297	number of commands used and their status, as well as its decision on the 
298	device queue depth change.
299	The heuristic used by the driver in handling QUEUE FULL ensures that the 
300	impact on performances is not too bad. You can get rid of the messages by 
301	setting verbose level to zero, as follow:
302	
303	1st method: boot your system using 'ncr53c8xx=verb:0' option.
304	2nd method: apply "setverbose 0" control command to the proc fs entry 
305	            corresponding to your controller after boot-up.
306	
307	6. Parity checking
308	
309	The driver supports SCSI parity checking and PCI bus master parity
310	checking.  These features must be enabled in order to ensure safe data
311	transfers.  However, some flawed devices or mother boards will have
312	problems with parity. You can disable either PCI parity or SCSI parity 
313	checking by entering appropriate options from the boot command line.
314	(See 10: Boot setup commands).
315	
316	7. Profiling information
317	
318	Profiling information is available through the proc SCSI file system.
319	Since gathering profiling information may impact performances, this 
320	feature is disabled by default and requires a compilation configuration 
321	option to be set to Y.
322	
323	The device associated with a host has the following pathname:
324	
325	          /proc/scsi/ncr53c8xx/N     (N=0,1,2 ....)
326	
327	Generally, only 1 board is used on hardware configuration, and that device is:
328	          /proc/scsi/ncr53c8xx/0
329	
330	However, if the driver has been made as module, the number of the
331	hosts is incremented each time the driver is loaded.
332	
333	In order to display profiling information, just enter:
334	
335	         cat /proc/scsi/ncr53c8xx/0
336	
337	and you will get something like the following text:
338	
339	-------------------------------------------------------
340	General information:
341	  Chip NCR53C810, device id 0x1, revision id 0x2
342	  IO port address 0x6000, IRQ number 10
343	  Using memory mapped IO at virtual address 0x282c000
344	  Synchronous transfer period 25, max commands per lun 4
345	Profiling information:
346	  num_trans    = 18014
347	  num_kbytes   = 671314
348	  num_disc     = 25763
349	  num_break    = 1673
350	  num_int      = 1685
351	  num_fly      = 18038
352	  ms_setup     = 4940
353	  ms_data      = 369940
354	  ms_disc      = 183090
355	  ms_post      = 1320
356	-------------------------------------------------------
357	
358	General information is easy to understand. The device ID and the
359	revision ID identify the SCSI chip as follows:
360	
361	Chip    Device id     Revision Id
362	----    ---------     -----------
363	810       0x1            <  0x10
364	810A      0x1            >= 0x10
365	815       0x4
366	825       0x3            <  0x10
367	860       0x6
368	825A      0x3            >= 0x10
369	875       0xf
370	895       0xc
371	
372	The profiling information is updated upon completion of SCSI commands.
373	A data structure is allocated and zeroed when the host adapter is
374	attached. So, if the driver is a module, the profile counters are
375	cleared each time the driver is loaded.  The "clearprof" command
376	allows you to clear these counters at any time.
377	
378	The following counters are available:
379	
380	("num" prefix means "number of",
381	"ms" means milli-seconds)
382	
383	num_trans
384		Number of completed commands
385		Example above: 18014 completed commands
386	
387	num_kbytes
388		Number of kbytes transferred
389		Example above: 671 MB transferred
390	
391	num_disc
392		Number of SCSI disconnections
393		Example above: 25763 SCSI disconnections
394	
395	num_break
396		number of script interruptions (phase mismatch)
397		Example above: 1673 script interruptions
398	
399	num_int
400		Number of interrupts other than "on the fly"
401		Example above: 1685 interruptions not "on the fly"
402	
403	num_fly
404		Number of interrupts "on the fly"
405		Example above: 18038 interruptions "on the fly"
406	
407	ms_setup
408		Elapsed time for SCSI commands setups
409		Example above: 4.94 seconds
410	
411	ms_data
412		Elapsed time for data transfers
413		Example above: 369.94 seconds spent for data transfer
414	
415	ms_disc
416		Elapsed time for SCSI disconnections
417		Example above: 183.09 seconds spent disconnected
418	
419	ms_post
420		Elapsed time for command post processing
421		(time from SCSI status get to command completion call)
422		Example above: 1.32 seconds spent for post processing
423	
424	Due to the 1/100 second tick of the system clock, "ms_post" time may
425	be wrong.
426	
427	In the example above, we got 18038 interrupts "on the fly" and only
428	1673 script breaks generally due to disconnections inside a segment 
429	of the scatter list.
430	
431	
432	8. Control commands
433	
434	Control commands can be sent to the driver with write operations to
435	the proc SCSI file system. The generic command syntax is the
436	following:
437	
438	      echo "<verb> <parameters>" >/proc/scsi/ncr53c8xx/0
439	      (assumes controller number is 0)
440	
441	Using "all" for "<target>" parameter with the commands below will
442	apply to all targets of the SCSI chain (except the controller).
443	
444	Available commands:
445	
446	8.1 Set minimum synchronous period factor
447	
448	    setsync <target> <period factor>
449	
450	    target:    target number
451	    period:    minimum synchronous period.
452	               Maximum speed = 1000/(4*period factor) except for special
453	               cases below.
454	
455	    Specify a period of 255, to force asynchronous transfer mode.
456	
457	      10 means 25 nano-seconds synchronous period
458	      11 means 30 nano-seconds synchronous period
459	      12 means 50 nano-seconds synchronous period
460	
461	8.2 Set wide size
462	
463	    setwide <target> <size>
464	
465	    target:    target number
466	    size:      0=8 bits, 1=16bits
467	
468	8.3 Set maximum number of concurrent tagged commands
469	 
470	    settags <target> <tags>
471	
472	    target:    target number
473	    tags:      number of concurrent tagged commands
474	               must not be greater than SCSI_NCR_MAX_TAGS (default: 8)
475	
476	8.4 Set order type for tagged command
477	
478	    setorder <order>
479	
480	    order:     3 possible values:
481	               simple: use SIMPLE TAG for all operations (read and write)
482	               ordered: use ORDERED TAG for all operations
483	               default: use default tag type,
484	                        SIMPLE  TAG for read  operations
485	                        ORDERED TAG for write operations
486	
487	
488	8.5 Set debug mode
489	
490	    setdebug <list of debug flags>
491	
492	    Available debug flags:
493	        alloc:   print info about memory allocations (ccb, lcb)
494	        queue:   print info about insertions into the command start queue
495	        result:  print sense data on CHECK CONDITION status
496	        scatter: print info about the scatter process
497	        scripts: print info about the script binding process
498		tiny:    print minimal debugging information
499		timing:  print timing information of the NCR chip
500		nego:    print information about SCSI negotiations
501		phase:   print information on script interruptions
502	
503	    Use "setdebug" with no argument to reset debug flags.
504	
505	
506	8.6 Clear profile counters
507	
508	    clearprof
509	
510	    The profile counters are automatically cleared when the amount of
511	    data transferred reaches 1000 GB in order to avoid overflow.
512	    The "clearprof" command allows you to clear these counters at any time.
513	
514	
515	8.7 Set flag (no_disc)
516	 
517	    setflag <target> <flag>
518	
519	    target:    target number
520	
521	    For the moment, only one flag is available:
522	
523	        no_disc:   not allow target to disconnect.
524	
525	    Do not specify any flag in order to reset the flag. For example:
526	    - setflag 4
527	      will reset no_disc flag for target 4, so will allow it disconnections.
528	    - setflag all
529	      will allow disconnection for all devices on the SCSI bus.
530	
531	
532	8.8 Set verbose level
533	
534	    setverbose #level
535	
536	    The driver default verbose level is 1. This command allows to change 
537	    th driver verbose level after boot-up.
538	
539	8.9 Reset all logical units of a target
540	
541	    resetdev <target>
542	
543	    target:    target number
544	    The driver will try to send a BUS DEVICE RESET message to the target.
545	    (Only supported by the SYM53C8XX driver and provided for test purpose)
546	
547	8.10 Abort all tasks of all logical units of a target
548	
549	    cleardev <target>
550	
551	    target:    target number
552	    The driver will try to send a ABORT message to all the logical units 
553	    of the target.
554	    (Only supported by the SYM53C8XX driver and provided for test purpose)
555	
556	
557	9. Configuration parameters
558	
559	If the firmware of all your devices is perfect enough, all the
560	features supported by the driver can be enabled at start-up.  However,
561	if only one has a flaw for some SCSI feature, you can disable the
562	support by the driver of this feature at linux start-up and enable
563	this feature after boot-up only for devices that support it safely.
564	
565	CONFIG_SCSI_NCR53C8XX_IOMAPPED       (default answer: n)
566	    Answer "y" if you suspect your mother board to not allow memory mapped I/O.
567	    May slow down performance a little.  This option is required by
568	    Linux/PPC and is used no matter what you select here.  Linux/PPC
569	    suffers no performance loss with this option since all IO is memory
570	    mapped anyway.
571	
572	CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS    (default answer: 8)
573	    Default tagged command queue depth.
574	
575	CONFIG_SCSI_NCR53C8XX_MAX_TAGS         (default answer: 8)
576	    This option allows you to specify the maximum number of tagged commands 
577	    that can be queued to a device. The maximum supported value is 32.
578	
579	CONFIG_SCSI_NCR53C8XX_SYNC            (default answer: 5)
580	    This option allows you to specify the frequency in MHz the driver 
581	    will use at boot time for synchronous data transfer negotiations.
582	    This frequency can be changed later with the "setsync" control command.
583	    0 means "asynchronous data transfers".
584	
585	CONFIG_SCSI_NCR53C8XX_FORCE_SYNC_NEGO (default answer: n)
586	    Force synchronous negotiation for all SCSI-2 devices.
587	    Some SCSI-2 devices do not report this feature in byte 7 of inquiry 
588	    response but do support it properly (TAMARACK scanners for example).
589	
590	CONFIG_SCSI_NCR53C8XX_NO_DISCONNECT   (default and only reasonable answer: n)
591	    If you suspect a device of yours does not properly support disconnections,
592	    you can answer "y". Then, all SCSI devices will never disconnect the bus 
593	    even while performing long SCSI operations.
594	
595	CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT
596	    Genuine SYMBIOS boards use GPIO0 in output for controller LED and GPIO3 
597	    bit as a flag indicating singled-ended/differential interface.
598	    If all the boards of your system are genuine SYMBIOS boards or use
599	    BIOS and drivers from SYMBIOS, you would want to enable this option.
600	    This option must NOT be enabled if your system has at least one 53C8XX 
601	    based scsi board with a vendor-specific BIOS.
602	    For example, Tekram DC-390/U, DC-390/W and DC-390/F scsi controllers 
603	    use a vendor-specific BIOS and are known to not use SYMBIOS compatible 
604	    GPIO wiring. So, this option must not be enabled if your system has 
605	    such a board installed.
606	
607	CONFIG_SCSI_NCR53C8XX_NVRAM_DETECT
608	    Enable support for reading the serial NVRAM data on Symbios and
609	    some Symbios compatible cards, and Tekram DC390W/U/F cards. Useful for
610	    systems with more than one Symbios compatible controller where at least
611	    one has a serial NVRAM, or for a system with a mixture of Symbios and
612	    Tekram cards. Enables setting the boot order of host adaptors
613	    to something other than the default order or "reverse probe" order. 
614	    Also enables Symbios and Tekram cards to be distinguished so
615	    CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT may be set in a system with a
616	    mixture of Symbios and Tekram cards so the Symbios cards can make use of
617	    the full range of Symbios features, differential, led pin, without
618	    causing problems for the Tekram card(s).
619	
620	10. Boot setup commands
621	
622	10.1 Syntax
623	
624	Setup commands can be passed to the driver either at boot time or as a 
625	string variable using 'insmod'.
626	
627	A boot setup command for the ncr53c8xx (sym53c8xx) driver begins with the 
628	driver name "ncr53c8xx="(sym53c8xx). The kernel syntax parser then expects 
629	an optional list of integers separated with comma followed by an optional 
630	list of comma-separated strings. Example of boot setup command under lilo 
631	prompt:
632	
633	lilo: linux root=/dev/hda2 ncr53c8xx=tags:4,sync:10,debug:0x200
634	
635	- enable tagged commands, up to 4 tagged commands queued.
636	- set synchronous negotiation speed to 10 Mega-transfers / second.
637	- set DEBUG_NEGO flag.
638	
639	Since comma seems not to be allowed when defining a string variable using  
640	'insmod', the driver also accepts <space> as option separator. 
641	The following command will install driver module with the same options as 
642	above.
643	
644	    insmod ncr53c8xx.o ncr53c8xx="tags:4 sync:10 debug:0x200"
645	
646	For the moment, the integer list of arguments is discarded by the driver. 
647	It will be used in the future in order to allow a per controller setup.
648	
649	Each string argument must be specified as "keyword:value". Only lower-case 
650	characters and digits are allowed.
651	
652	In a system that contains multiple 53C8xx adapters insmod will install the 
653	specified driver on each adapter. To exclude a chip use the 'excl' keyword.
654	
655	The sequence of commands, 
656	
657	    insmod sym53c8xx sym53c8xx=excl:0x1400
658	    insmod ncr53c8xx
659	
660	installs the sym53c8xx driver on all adapters except the one at IO port 
661	address 0x1400 and then installs the ncr53c8xx driver to the adapter at IO 
662	port address 0x1400.
663	
664	
665	10.2 Available arguments
666	
667	10.2.1  Master parity checking
668	        mpar:y     enabled
669	        mpar:n     disabled
670	
671	10.2.2  Scsi parity checking
672	        spar:y     enabled
673	        spar:n     disabled
674	
675	10.2.3  Scsi disconnections
676	        disc:y     enabled
677	        disc:n     disabled
678	 
679	10.2.4  Special features
680	   Only apply to 810A, 825A, 860, 875 and 895 controllers.
681	   Have no effect with other ones.
682	        specf:y    (or 1) enabled
683	        specf:n    (or 0) disabled
684	        specf:3           enabled except Memory Write And Invalidate
685	   The default driver setup is 'specf:3'. As a consequence, option 'specf:y' 
686	   must be specified in the boot setup command to enable Memory Write And 
687	   Invalidate.
688	
689	10.2.5  Ultra SCSI support
690	   Only apply to 860, 875, 895, 895a, 896, 1010 and 1010_66 controllers.
691	   Have no effect with other ones.
692	        ultra:n    All ultra speeds enabled
693	        ultra:2    Ultra2 enabled
694	        ultra:1    Ultra enabled
695	        ultra:0    Ultra speeds disabled
696	
697	10.2.6  Default number of tagged commands
698	        tags:0     (or tags:1 ) tagged command queuing disabled
699	        tags:#tags (#tags  > 1) tagged command queuing enabled
700	  #tags will be truncated to the max queued commands configuration parameter.
701	  This option also allows to specify a command queue depth for each device 
702	  that support tagged command queueing.
703	  Example:
704	      ncr53c8xx=tags:10/t2t3q16-t5q24/t1u2q32
705	               will set devices queue depth as follow:
706	      - controller #0 target #2 and target #3                  -> 16 commands,
707	      - controller #0 target #5                                -> 24 commands,
708	      - controller #1 target #1 logical unit #2                -> 32 commands,
709	      - all other logical units (all targets, all controllers) -> 10 commands.
710	
711	10.2.7  Default synchronous period factor
712	        sync:255     disabled (asynchronous transfer mode)
713	        sync:#factor
714	  #factor = 10     Ultra-2 SCSI 40 Mega-transfers / second
715	  #factor = 11     Ultra-2 SCSI 33 Mega-transfers / second
716	  #factor < 25     Ultra   SCSI 20 Mega-transfers / second
717	  #factor < 50     Fast    SCSI-2
718	
719	  In all cases, the driver will use the minimum transfer period supported by 
720	  controllers according to NCR53C8XX chip type.
721	
722	10.2.8  Negotiate synchronous with all devices
723	        (force sync nego)
724	        fsn:y      enabled
725	        fsn:n      disabled
726	
727	10.2.9  Verbosity level
728	        verb:0     minimal
729	        verb:1     normal
730	        verb:2     too much
731	
732	10.2.10 Debug mode
733	        debug:0	 clear debug flags
734	        debug:#x   set debug flags
735	  #x is an integer value combining the following power-of-2 values:
736	  DEBUG_ALLOC       0x1
737	  DEBUG_PHASE       0x2
738	  DEBUG_POLL        0x4
739	  DEBUG_QUEUE       0x8
740	  DEBUG_RESULT     0x10
741	  DEBUG_SCATTER    0x20
742	  DEBUG_SCRIPT     0x40
743	  DEBUG_TINY       0x80
744	  DEBUG_TIMING    0x100
745	  DEBUG_NEGO      0x200
746	  DEBUG_TAGS      0x400
747	  DEBUG_FREEZE    0x800
748	  DEBUG_RESTART  0x1000
749	
750	  You can play safely with DEBUG_NEGO. However, some of these flags may 
751	  generate bunches of syslog messages. 
752	
753	10.2.11 Burst max
754	        burst:0    burst disabled
755	        burst:255  get burst length from initial IO register settings.
756	        burst:#x   burst enabled (1<<#x burst transfers max)
757	  #x is an integer value which is log base 2 of the burst transfers max.
758	  The NCR53C875 and NCR53C825A support up to 128 burst transfers (#x = 7).
759	  Other chips only support up to 16 (#x = 4).
760	  This is a maximum value. The driver set the burst length according to chip 
761	  and revision ids. By default the driver uses the maximum value supported 
762	  by the chip.
763	
764	10.2.12 LED support
765	        led:1      enable  LED support
766	        led:0      disable LED support
767	  Donnot enable LED support if your scsi board does not use SDMS BIOS.
768	  (See 'Configuration parameters')
769	
770	10.2.13 Max wide
771	        wide:1      wide scsi enabled
772	        wide:0      wide scsi disabled
773	  Some scsi boards use a 875 (ultra wide) and only supply narrow connectors.
774	  If you have connected a wide device with a 50 pins to 68 pins cable 
775	  converter, any accepted wide negotiation will break further data transfers.
776	  In such a case, using "wide:0" in the bootup command will be helpful. 
777	
778	10.2.14 Differential mode
779	        diff:0	never set up diff mode
780	        diff:1	set up diff mode if BIOS set it
781	        diff:2	always set up diff mode
782	        diff:3	set diff mode if GPIO3 is not set
783	
784	10.2.15 IRQ mode
785	        irqm:0     always open drain
786	        irqm:1     same as initial settings (assumed BIOS settings)
787	        irqm:2     always totem pole
788	        irqm:0x10  driver will not use IRQF_SHARED flag when requesting irq
789	        irqm:0x20  driver will not use IRQF_DISABLED flag when requesting irq
790	
791	    (Bits 0x10 and 0x20 can be combined with hardware irq mode option)
792	
793	10.2.16 Reverse probe
794	        revprob:n   probe chip ids from the PCI configuration in this order:
795	                    810, 815, 820, 860, 875, 885, 895, 896
796	        revprob:y   probe chip ids in the reverse order.
797	
798	10.2.17 Fix up PCI configuration space
799	        pcifix:<option bits>
800	
801	    Available option bits:
802	        0x0:   No attempt to fix PCI configuration space registers values.
803	        0x1:   Set PCI cache-line size register if not set.
804	        0x2:   Set write and invalidate bit in PCI command register.
805	        0x4:   Increase if necessary PCI latency timer according to burst max.
806	
807	    Use 'pcifix:7' in order to allow the driver to fix up all PCI features.
808	
809	10.2.18 Serial NVRAM
810	        nvram:n     do not look for serial NVRAM
811	        nvram:y     test controllers for onboard serial NVRAM
812	        (alternate binary form)
813	        mvram=<bits options>
814	        0x01   look for NVRAM  (equivalent to nvram=y)
815	        0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
816	        0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
817	        0x08   ignore NVRAM "Scan at boot time" parameter for all devices
818	        0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
819	
820	10.2.19 Check SCSI BUS 
821	        buschk:<option bits>
822	
823	    Available option bits:
824	        0x0:   No check.
825	        0x1:   Check and do not attach the controller on error.  
826	        0x2:   Check and just warn on error.
827	        0x4:   Disable SCSI bus integrity checking.
828	
829	10.2.20 Exclude a host from being attached
830	        excl=<io_address>
831	
832	    Prevent host at a given io address from being attached.
833	    For example 'ncr53c8xx=excl:0xb400,excl:0xc000' indicate to the 
834	    ncr53c8xx driver not to attach hosts at address 0xb400 and 0xc000.
835	
836	10.2.21 Suggest a default SCSI id for hosts
837	        hostid:255	no id suggested.
838	        hostid:#x   (0 < x < 7) x suggested for hosts SCSI id.
839	
840	    If a host SCSI id is available from the NVRAM, the driver will ignore 
841	    any value suggested as boot option. Otherwise, if a suggested value 
842	    different from 255 has been supplied, it will use it. Otherwise, it will 
843	    try to deduce the value previously set in the hardware and use value 
844	    7 if the hardware value is zero.
845	
846	10.2.22 Enable use of IMMEDIATE ARBITRATION
847	        (only supported by the sym53c8xx driver. See 10.7 for more details)
848	        iarb:0    do not use this feature.
849	        iarb:#x   use this feature according to bit fields as follow:
850	
851	    bit 0 (1) : enable IARB each time the initiator has been reselected 
852	                when it arbitrated for the SCSI BUS.
853	    (#x >> 4) : maximum number of successive settings of IARB if the initiator 
854	                win arbitration and it has other commands to send to a device.
855	
856	Boot fail safe
857	    safe:y	load the following assumed fail safe initial setup
858	
859	  master parity			disabled		mpar:n
860	  scsi parity			enabled			spar:y
861	  disconnections		not allowed		disc:n
862	  special features		disabled		specf:n
863	  ultra scsi			disabled		ultra:n
864	  force sync negotiation	disabled		fsn:n
865	  reverse probe			disabled		revprob:n
866	  PCI fix up                    disabled                pcifix:0
867	  serial NVRAM                  enabled                 nvram:y
868	  verbosity level		2			verb:2
869	  tagged command queuing	disabled		tags:0
870	  synchronous negotiation	disabled		sync:255
871	  debug flags			none			debug:0
872	  burst length			from BIOS settings	burst:255
873	  LED support			disabled		led:0
874	  wide support			disabled		wide:0
875	  settle time			10 seconds		settle:10
876	  differential support		from BIOS settings	diff:1
877	  irq mode			from BIOS settings	irqm:1
878	  SCSI BUS check		do not attach on error	buschk:1
879	  immediate arbitration		disabled		iarb:0
880	
881	10.3 Advised boot setup commands
882	
883	If the driver has been configured with default options, the equivalent 
884	boot setup is:
885	
886	   ncr53c8xx=mpar:y,spar:y,disc:y,specf:3,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
887	             tags:0,sync:50,debug:0,burst:7,led:0,wide:1,settle:2,diff:0,irqm:0
888	
889	For an installation diskette or a safe but not fast system,
890	boot setup can be:
891	
892	    ncr53c8xx=safe:y,mpar:y,disc:y
893	    ncr53c8xx=safe:y,disc:y
894	    ncr53c8xx=safe:y,mpar:y
895	    ncr53c8xx=safe:y
896	
897	My personal system works flawlessly with the following equivalent setup:
898	
899	   ncr53c8xx=mpar:y,spar:y,disc:y,specf:1,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
900	             tags:32,sync:12,debug:0,burst:7,led:1,wide:1,settle:2,diff:0,irqm:0
901	
902	The driver prints its actual setup when verbosity level is 2. You can try 
903	"ncr53c8xx=verb:2" to get the "static" setup of the driver, or add "verb:2" 
904	to your boot setup command in order to check the actual setup the driver is 
905	using.
906	
907	10.4 PCI configuration fix-up boot option
908	
909	pcifix:<option bits>
910	
911	Available option bits:
912	    0x1:     Set PCI cache-line size register if not set.
913	    0x2:     Set write and invalidate bit in PCI command register.
914	
915	Use 'pcifix:3' in order to allow the driver to fix both PCI features.
916	
917	These options only apply to new SYMBIOS chips 810A, 825A, 860, 875 
918	and 895 and are only supported for Pentium and 486 class processors.
919	Recent SYMBIOS 53C8XX scsi processors are able to use PCI read multiple 
920	and PCI write and invalidate commands. These features require the 
921	cache line size register to be properly set in the PCI configuration 
922	space of the chips. On the other hand, chips will use PCI write and 
923	invalidate commands only if the corresponding bit is set to 1 in the 
924	PCI command register.
925	
926	Not all PCI bioses set the PCI cache line register and the PCI write and 
927	invalidate bit in the PCI configuration space of 53C8XX chips.
928	Optimized PCI accesses may be broken for some PCI/memory controllers or 
929	make problems with some PCI boards.
930	
931	This fix-up worked flawlessly on my previous system.
932	(MB Triton HX / 53C875 / 53C810A)
933	I use these options at my own risks as you will do if you decide to 
934	use them too.
935	
936	
937	10.5 Serial NVRAM support boot option
938	
939	nvram:n     do not look for serial NVRAM
940	nvram:y     test controllers for onboard serial NVRAM
941	
942	This option can also been entered as an hexadecimal value that allows 
943	to control what information the driver will get from the NVRAM and what 
944	information it will ignore.
945	For details see '17. Serial NVRAM support'.
946	
947	When this option is enabled, the driver tries to detect all boards using 
948	a Serial NVRAM. This memory is used to hold user set up parameters.
949	
950	The parameters the driver is able to get from the NVRAM depend on the 
951	data format used, as follow:
952	
953	                                 Tekram format      Symbios format
954	General and host parameters
955	    Boot order                         N                   Y
956	    Host SCSI ID                       Y                   Y
957	    SCSI parity checking               Y                   Y
958	    Verbose boot messages              N                   Y
959	SCSI devices parameters
960	    Synchronous transfer speed         Y                   Y
961	    Wide 16 / Narrow                   Y                   Y
962	    Tagged Command Queuing enabled     Y                   Y
963	    Disconnections enabled             Y                   Y
964	    Scan at boot time                  N                   Y
965	
966	In order to speed up the system boot, for each device configured without 
967	the "scan at boot time" option, the driver forces an error on the 
968	first TEST UNIT READY command received for this device.
969	
970	Some SDMS BIOS revisions seem to be unable to boot cleanly with very fast 
971	hard disks. In such a situation you cannot configure the NVRAM with 
972	optimized parameters value.
973	
974	The 'nvram' boot option can be entered in hexadecimal form in order 
975	to ignore some options configured in the NVRAM, as follow:
976	
977	mvram=<bits options>
978	      0x01   look for NVRAM  (equivalent to nvram=y)
979	      0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
980	      0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
981	      0x08   ignore NVRAM "Scan at boot time" parameter for all devices
982	      0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
983	
984	Option 0x80 is only supported by the sym53c8xx driver and is disabled by 
985	default. Result is that, by default (option not set), the sym53c8xx driver 
986	will not attach controllers set to OFF in the NVRAM.
987	
988	The ncr53c8xx always tries to attach all the controllers. Option 0x80 has 
989	not been added to the ncr53c8xx driver, since it has been reported to 
990	confuse users who use this driver since a long time. If you desire a 
991	controller not to be attached by the ncr53c8xx driver at Linux boot, you 
992	must use the 'excl' driver boot option.
993	
994	10.6 SCSI BUS checking boot option.
995	
996	When this option is set to a non-zero value, the driver checks SCSI lines 
997	logic state, 100 micro-seconds after having asserted the SCSI RESET line.
998	The driver just reads SCSI lines and checks all lines read FALSE except RESET.
999	Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI 
1000	RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem.
1001	Unfortunately, the following common SCSI BUS problems are not detected:
1002	- Only 1 terminator installed.
1003	- Misplaced terminators.
1004	- Bad quality terminators.
1005	On the other hand, either bad cabling, broken devices, not conformant 
1006	devices, ... may cause a SCSI signal to be wrong when te driver reads it.
1007	
1008	10.7 IMMEDIATE ARBITRATION boot option
1009	
1010	This option is only supported by the SYM53C8XX driver (not by the NCR53C8XX).
1011	
1012	SYMBIOS 53C8XX chips are able to arbitrate for the SCSI BUS as soon as they 
1013	have detected an expected disconnection (BUS FREE PHASE). For this process 
1014	to be started, bit 1 of SCNTL1 IO register must be set when the chip is 
1015	connected to the SCSI BUS.
1016	
1017	When this feature has been enabled for the current connection, the chip has 
1018	every chance to win arbitration if only devices with lower priority are 
1019	competing for the SCSI BUS. By the way, when the chip is using SCSI id 7, 
1020	then it will for sure win the next SCSI BUS arbitration.
1021	
1022	Since, there is no way to know what devices are trying to arbitrate for the 
1023	BUS, using this feature can be extremely unfair. So, you are not advised
1024	to enable it, or at most enable this feature for the case the chip lost 
1025	the previous arbitration (boot option 'iarb:1').
1026	
1027	This feature has the following advantages:
1028	
1029	a) Allow the initiator with ID 7 to win arbitration when it wants so.
1030	b) Overlap at least 4 micro-seconds of arbitration time with the execution 
1031	   of SCRIPTS that deal with the end of the current connection and that 
1032	   starts the next job.
1033	
1034	Hmmm... But (a) may just prevent other devices from reselecting the initiator, 
1035	and delay data transfers or status/completions, and (b) may just waste 
1036	SCSI BUS bandwidth if the SCRIPTS execution lasts more than 4 micro-seconds.
1037	
1038	The use of IARB needs the SCSI_NCR_IARB_SUPPORT option to have been defined 
1039	at compile time and the 'iarb' boot option to have been set to a non zero 
1040	value at boot time. It is not that useful for real work, but can be used 
1041	to stress SCSI devices or for some applications that can gain advantage of 
1042	it. By the way, if you experience badnesses like 'unexpected disconnections', 
1043	'bad reselections', etc... when using IARB on heavy IO load, you should not 
1044	be surprised, because force-feeding anything and blocking its arse at the 
1045	same time cannot work for a long time. :-))
1046	
1047	
1048	11. Some constants and flags of the ncr53c8xx.h header file
1049	
1050	Some of these are defined from the configuration parameters.  To
1051	change other "defines", you must edit the header file.  Do that only
1052	if you know what you are doing.
1053	
1054	SCSI_NCR_SETUP_SPECIAL_FEATURES	(default: defined)
1055		If defined, the driver will enable some special features according  
1056		to chip and revision id.
1057	        For 810A, 860, 825A, 875 and 895 scsi chips, this option enables 
1058		support of features that reduce load of PCI bus and memory accesses 
1059		during  scsi transfer processing: burst op-code fetch, read multiple, 
1060	        read line, prefetch, cache line, write and invalidate, 
1061	        burst 128 (875 only), large dma fifo (875 only), offset 16 (875 only).
1062		Can be changed by the following boot setup command:
1063			ncr53c8xx=specf:n
1064	
1065	SCSI_NCR_IOMAPPED		(default: not defined)
1066		If defined, normal I/O is forced.
1067	
1068	SCSI_NCR_SHARE_IRQ		(default: defined)
1069		If defined, request shared IRQ.
1070		
1071	SCSI_NCR_MAX_TAGS		(default: 8)
1072		Maximum number of simultaneous tagged commands to a device.
1073		Can be changed by "settags <target> <maxtags>"
1074	
1075	SCSI_NCR_SETUP_DEFAULT_SYNC     (default: 50)
1076		Transfer period factor the driver will use at boot time for synchronous 
1077		negotiation. 0 means asynchronous.
1078		Can be changed by "setsync <target> <period factor>"
1079	
1080	SCSI_NCR_SETUP_DEFAULT_TAGS     (default: 8)
1081		Default number of simultaneous tagged commands to a device.
1082		< 1 means tagged command queuing disabled at start-up.
1083	
1084	SCSI_NCR_ALWAYS_SIMPLE_TAG	(default: defined)
1085		Use SIMPLE TAG for read and write commands.
1086		Can be changed by "setorder <ordered|simple|default>"
1087	
1088	SCSI_NCR_SETUP_DISCONNECTION	(default: defined)
1089		If defined, targets are allowed to disconnect.
1090	
1091	SCSI_NCR_SETUP_FORCE_SYNC_NEGO	(default: not defined)
1092		If defined, synchronous negotiation is tried for all SCSI-2 devices.
1093		Can be changed by "setsync <target> <period>"
1094	
1095	SCSI_NCR_SETUP_MASTER_PARITY	(default: defined)
1096		If defined, master parity checking is enabled.
1097	
1098	SCSI_NCR_SETUP_MASTER_PARITY	(default: defined)
1099		If defined, SCSI parity checking is enabled.
1100	
1101	SCSI_NCR_PROFILE_SUPPORT	(default: not defined)
1102		If defined, profiling information is gathered.
1103	
1104	SCSI_NCR_MAX_SCATTER		(default: 128)
1105		Scatter list size of the driver ccb.
1106	
1107	SCSI_NCR_MAX_TARGET		(default: 16)
1108		Max number of targets per host.
1109	
1110	SCSI_NCR_MAX_HOST		(default: 2)
1111		Max number of host controllers.
1112	
1113	SCSI_NCR_SETTLE_TIME		(default: 2)
1114		Number of seconds the driver will wait after reset.
1115	
1116	SCSI_NCR_TIMEOUT_ALERT		(default: 3)
1117		If a pending command will time out after this amount of seconds,
1118		an ordered tag is used for the next command.
1119		Avoids timeouts for unordered tagged commands.
1120	
1121	SCSI_NCR_CAN_QUEUE		(default: 7*SCSI_NCR_MAX_TAGS)
1122		Max number of commands that can be queued to a host.
1123	
1124	SCSI_NCR_CMD_PER_LUN		(default: SCSI_NCR_MAX_TAGS)
1125		Max number of commands queued to a host for a device.
1126	
1127	SCSI_NCR_SG_TABLESIZE		(default: SCSI_NCR_MAX_SCATTER-1)
1128		Max size of the Linux scatter/gather list.
1129	
1130	SCSI_NCR_MAX_LUN	(default: 8)
1131		Max number of LUNs per target.
1132	
1133	
1134	12. Installation
1135	
1136	This driver is part of the linux kernel distribution.
1137	Driver files are located in the sub-directory "drivers/scsi" of the 
1138	kernel source tree.
1139	
1140	Driver files:
1141	
1142		README.ncr53c8xx	: this file
1143		ChangeLog.ncr53c8xx	: change log
1144		ncr53c8xx.h		: definitions
1145		ncr53c8xx.c		: the driver code
1146	
1147	New driver versions are made available separately in order to allow testing 
1148	changes and new features prior to including them into the linux kernel 
1149	distribution. The following URL provides information on latest available 
1150	patches: 
1151	
1152	      ftp://ftp.tux.org/pub/people/gerard-roudier/README
1153	
1154	
1155	13. Architecture dependent features.
1156	
1157	<Not yet written>
1158	
1159	
1160	14. Known problems
1161	
1162	14.1 Tagged commands with Iomega Jaz device
1163	
1164	I have not tried this device, however it has been reported to me the
1165	following: This device is capable of Tagged command queuing. However
1166	while spinning up, it rejects Tagged commands. This behaviour is
1167	conforms to 6.8.2 of SCSI-2 specifications. The current behaviour of
1168	the driver in that situation is not satisfying. So do not enable
1169	Tagged command queuing for devices that are able to spin down.  The
1170	other problem that may appear is timeouts. The only way to avoid
1171	timeouts seems to edit linux/drivers/scsi/sd.c and to increase the
1172	current timeout values.
1173	
1174	14.2 Device names change when another controller is added.
1175	
1176	When you add a new NCR53C8XX chip based controller to a system that already 
1177	has one or more controllers of this family, it may happen that the order 
1178	the driver registers them to the kernel causes problems due to device 
1179	name changes.
1180	When at least one controller uses NvRAM, SDMS BIOS version 4 allows you to 
1181	define the order the BIOS will scan the scsi boards. The driver attaches 
1182	controllers according to BIOS information if NvRAM detect option is set.
1183	
1184	If your controllers do not have NvRAM, you can:
1185	
1186	- Ask the driver to probe chip ids in reverse order from the boot command
1187	  line: ncr53c8xx=revprob:y
1188	- Make appropriate changes in the fstab.
1189	- Use the 'scsidev' tool from Eric Youngdale.
1190	
1191	14.3 Using only 8 bit devices with a WIDE SCSI controller.
1192	
1193	When only 8 bit NARROW devices are connected to a 16 bit WIDE SCSI controller, 
1194	you must ensure that lines of the wide part of the SCSI BUS are pulled-up.
1195	This can be achieved by ENABLING the WIDE TERMINATOR portion of the SCSI 
1196	controller card.
1197	The TYAN 1365 documentation revision 1.2 is not correct about such settings.
1198	(page 10, figure 3.3).
1199	
1200	14.4 Possible data corruption during a Memory Write and Invalidate
1201	
1202	This problem is described in SYMBIOS DEL 397, Part Number 69-039241, ITEM 4.
1203	
1204	In some complex situations, 53C875 chips revision <= 3 may start a PCI 
1205	Write and Invalidate Command at a not cache-line-aligned 4 DWORDS boundary.
1206	This is only possible when Cache Line Size is 8 DWORDS or greater.
1207	Pentium systems use a 8 DWORDS cache line size and so are concerned by 
1208	this chip bug, unlike i486 systems that use a 4 DWORDS cache line size.
1209	
1210	When this situation occurs, the chip may complete the Write and Invalidate 
1211	command after having only filled part of the last cache line involved in 
1212	the transfer, leaving to data corruption the remainder of this cache line.
1213	
1214	Not using Write And Invalidate obviously gets rid of this chip bug, and so 
1215	it is now the default setting of the driver.
1216	However, for people like me who want to enable this feature, I have added 
1217	part of a work-around suggested by SYMBIOS. This work-around resets the 
1218	addressing logic when the DATA IN phase is entered and so prevents the bug 
1219	from being triggered for the first SCSI MOVE of the phase. This work-around 
1220	should be enough according to the following:
1221	
1222	The only driver internal data structure that is greater than 8 DWORDS  and 
1223	that is moved by the SCRIPTS processor is the 'CCB header' that contains 
1224	the context of the SCSI transfer. This data structure is aligned on 8 DWORDS 
1225	boundary (Pentium Cache Line Size), and so is immune to this chip bug, at 
1226	least on Pentium systems.
1227	But the conditions of this bug can be met when a SCSI read command is 
1228	performed using a buffer that is 4 DWORDS but not cache-line aligned.
1229	This cannot happen under Linux when scatter/gather lists are used since 
1230	they only refer to system buffers that are well aligned. So, a work around 
1231	may only be needed under Linux when a scatter/gather list is not used and 
1232	when the SCSI DATA IN phase is reentered after a phase mismatch.
1233	
1234	14.5 IRQ sharing problems
1235	
1236	When an IRQ is shared by devices that are handled by different drivers, it 
1237	may happen that one driver complains about the request of the IRQ having 
1238	failed. Inder Linux-2.0, this may be due to one driver having requested the 
1239	IRQ using the IRQF_DISABLED flag but some other having requested the same IRQ
1240	without this flag. Under both Linux-2.0 and linux-2.2, this may be caused by 
1241	one driver not having requested the IRQ with the IRQF_SHARED flag.
1242	
1243	By default, the ncr53c8xx and sym53c8xx drivers request IRQs with both the 
1244	IRQF_DISABLED and the IRQF_SHARED flag under Linux-2.0 and with only the IRQF_SHARED
1245	flag under Linux-2.2.
1246	
1247	Under Linux-2.0, you can disable use of IRQF_DISABLED flag from the boot
1248	command line by using the following option:
1249	
1250	     ncr53c8xx=irqm:0x20   (for the generic ncr53c8xx driver)
1251	     sym53c8xx=irqm:0x20   (for the sym53c8xx driver)
1252	
1253	If this does not fix the problem, then you may want to check how all other 
1254	drivers are requesting the IRQ and report the problem. Note that if at least 
1255	a single driver does not request the IRQ with the IRQF_SHARED flag (share IRQ),
1256	then the request of the IRQ obviously will not succeed for all the drivers.
1257	
1258	15. SCSI problem troubleshooting
1259	
1260	15.1 Problem tracking
1261	
1262	Most SCSI problems are due to a non conformant SCSI bus or to buggy
1263	devices.  If unfortunately you have SCSI problems, you can check the
1264	following things:
1265	
1266	- SCSI bus cables
1267	- terminations at both end of the SCSI chain
1268	- linux syslog messages (some of them may help you)
1269	
1270	If you do not find the source of problems, you can configure the
1271	driver with no features enabled.
1272	
1273	- only asynchronous data transfers
1274	- tagged commands disabled
1275	- disconnections not allowed
1276	
1277	Now, if your SCSI bus is ok, your system have every chance to work
1278	with this safe configuration but performances will not be optimal.
1279	
1280	If it still fails, then you can send your problem description to
1281	appropriate mailing lists or news-groups.  Send me a copy in order to
1282	be sure I will receive it.  Obviously, a bug in the driver code is
1283	possible.
1284	
1285	     My email address: Gerard Roudier <groudier@free.fr>
1286	
1287	Allowing disconnections is important if you use several devices on
1288	your SCSI bus but often causes problems with buggy devices.
1289	Synchronous data transfers increases throughput of fast devices like
1290	hard disks.  Good SCSI hard disks with a large cache gain advantage of
1291	tagged commands queuing.
1292	
1293	Try to enable one feature at a time with control commands.  For example:
1294	
1295	- echo "setsync all 25" >/proc/scsi/ncr53c8xx/0
1296	  Will enable fast synchronous data transfer negotiation for all targets.
1297	
1298	- echo "setflag 3" >/proc/scsi/ncr53c8xx/0
1299	  Will reset flags (no_disc) for target 3, and so will allow it to disconnect 
1300	  the SCSI Bus.
1301	
1302	- echo "settags 3 8" >/proc/scsi/ncr53c8xx/0
1303	  Will enable tagged command queuing for target 3 if that device supports it.
1304	
1305	Once you have found the device and the feature that cause problems, just 
1306	disable that feature for that device.
1307	
1308	15.2 Understanding hardware error reports
1309	
1310	When the driver detects an unexpected error condition, it may display a 
1311	message of the following pattern.
1312	
1313	sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
1314	sym53c876-0: script cmd = 19000000
1315	sym53c876-0: regdump: da 10 80 95 47 0f 01 07 75 01 81 21 80 01 09 00.
1316	
1317	Some fields in such a message may help you understand the cause of the 
1318	problem, as follows:
1319	
1320	sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
1321	............A.........B.C....D.E..F....G.H.......I.....J...K.......
1322	
1323	Field A : target number.
1324	  SCSI ID of the device the controller was talking with at the moment the 
1325	  error occurs.
1326	
1327	Field B : DSTAT io register (DMA STATUS)
1328	  Bit 0x40 : MDPE Master Data Parity Error
1329	             Data parity error detected on the PCI BUS.
1330	  Bit 0x20 : BF   Bus Fault
1331	             PCI bus fault condition detected
1332	  Bit 0x01 : IID  Illegal Instruction Detected
1333	             Set by the chip when it detects an Illegal Instruction format 
1334	             on some condition that makes an instruction illegal.
1335	  Bit 0x80 : DFE Dma Fifo Empty
1336	             Pure status bit that does not indicate an error.
1337	  If the reported DSTAT value contains a combination of MDPE (0x40), 
1338	  BF (0x20), then the cause may be likely due to a PCI BUS problem.
1339	
1340	Field C : SIST io register (SCSI Interrupt Status)
1341	  Bit 0x08 : SGE  SCSI GROSS ERROR
1342	             Indicates that the chip detected a severe error condition 
1343	             on the SCSI BUS that prevents the SCSI protocol from functioning
1344	             properly.
1345	  Bit 0x04 : UDC  Unexpected Disconnection
1346	             Indicates that the device released the SCSI BUS when the chip 
1347	             was not expecting this to happen. A device may behave so to 
1348	             indicate the SCSI initiator that an error condition not reportable              using the SCSI protocol has occurred.
1349	  Bit 0x02 : RST  SCSI BUS Reset
1350	             Generally SCSI targets do not reset the SCSI BUS, although any 
1351	             device on the BUS can reset it at any time.
1352	  Bit 0x01 : PAR  Parity
1353	             SCSI parity error detected.
1354	  On a faulty SCSI BUS, any error condition among SGE (0x08), UDC (0x04) and 
1355	  PAR (0x01) may be detected by the chip. If your SCSI system sometimes 
1356	  encounters such error conditions, especially SCSI GROSS ERROR, then a SCSI 
1357	  BUS problem is likely the cause of these errors.
1358	
1359	For fields D,E,F,G and H, you may look into the sym53c8xx_defs.h file 
1360	that contains some minimal comments on IO register bits.
1361	Field D : SOCL  Scsi Output Control Latch
1362	          This register reflects the state of the SCSI control lines the 
1363	          chip want to drive or compare against.
1364	Field E : SBCL  Scsi Bus Control Lines
1365	          Actual value of control lines on the SCSI BUS.
1366	Field F : SBDL  Scsi Bus Data Lines
1367	          Actual value of data lines on the SCSI BUS.
1368	Field G : SXFER  SCSI Transfer
1369	          Contains the setting of the Synchronous Period for output and 
1370	          the current Synchronous offset (offset 0 means asynchronous).
1371	Field H : SCNTL3 Scsi Control Register 3
1372	          Contains the setting of timing values for both asynchronous and 
1373	          synchronous data transfers. 
1374	
1375	Understanding Fields I, J, K and dumps requires to have good knowledge of 
1376	SCSI standards, chip cores functionnals and internal driver data structures.
1377	You are not required to decode and understand them, unless you want to help 
1378	maintain the driver code.
1379	
1380	16. Synchronous transfer negotiation tables
1381	
1382	Tables below have been created by calling the routine the driver uses
1383	for synchronisation negotiation timing calculation and chip setting.
1384	The first table corresponds to Ultra chips 53875 and 53C860 with 80 MHz 
1385	clock and 5 clock divisors.
1386	The second one has been calculated by setting the scsi clock to 40 Mhz 
1387	and using 4 clock divisors and so applies to all NCR53C8XX chips in fast 
1388	SCSI-2 mode.
1389	
1390	Periods are in nano-seconds and speeds are in Mega-transfers per second.
1391	1 Mega-transfers/second means 1 MB/s with 8 bits SCSI and 2 MB/s with 
1392	Wide16 SCSI.
1393	
1394	16.1 Synchronous timings for 53C895, 53C875 and 53C860 SCSI controllers
1395	
1396	 ----------------------------------------------
1397	 Negotiated                     NCR settings
1398	 Factor   Period   Speed        Period   Speed
1399	 ------   ------   ------       ------   ------
1400	 10       25       40.000       25       40.000   (53C895 only)
1401	 11       30.2     33.112       31.25    32.000   (53C895 only)
1402	 12       50       20.000       50       20.000
1403	 13       52       19.230       62       16.000
1404	 14       56       17.857       62       16.000
1405	 15       60       16.666       62       16.000
1406	 16       64       15.625       75       13.333
1407	 17       68       14.705       75       13.333
1408	 18       72       13.888       75       13.333
1409	 19       76       13.157       87       11.428
1410	 20       80       12.500       87       11.428
1411	 21       84       11.904       87       11.428
1412	 22       88       11.363       93       10.666
1413	 23       92       10.869       93       10.666
1414	 24       96       10.416      100       10.000
1415	 25      100       10.000      100       10.000
1416	 26      104        9.615      112        8.888
1417	 27      108        9.259      112        8.888
1418	 28      112        8.928      112        8.888
1419	 29      116        8.620      125        8.000
1420	 30      120        8.333      125        8.000
1421	 31      124        8.064      125        8.000
1422	 32      128        7.812      131        7.619
1423	 33      132        7.575      150        6.666
1424	 34      136        7.352      150        6.666
1425	 35      140        7.142      150        6.666
1426	 36      144        6.944      150        6.666
1427	 37      148        6.756      150        6.666
1428	 38      152        6.578      175        5.714
1429	 39      156        6.410      175        5.714
1430	 40      160        6.250      175        5.714
1431	 41      164        6.097      175        5.714
1432	 42      168        5.952      175        5.714
1433	 43      172        5.813      175        5.714
1434	 44      176        5.681      187        5.333
1435	 45      180        5.555      187        5.333
1436	 46      184        5.434      187        5.333
1437	 47      188        5.319      200        5.000
1438	 48      192        5.208      200        5.000
1439	 49      196        5.102      200        5.000
1440	
1441	
1442	16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
1443	
1444	 ----------------------------------------------
1445	 Negotiated                     NCR settings
1446	 Factor   Period   Speed        Period   Speed
1447	 ------   ------   ------       ------   ------
1448	 25      100       10.000      100       10.000
1449	 26      104        9.615      125        8.000
1450	 27      108        9.259      125        8.000
1451	 28      112        8.928      125        8.000
1452	 29      116        8.620      125        8.000
1453	 30      120        8.333      125        8.000
1454	 31      124        8.064      125        8.000
1455	 32      128        7.812      131        7.619
1456	 33      132        7.575      150        6.666
1457	 34      136        7.352      150        6.666
1458	 35      140        7.142      150        6.666
1459	 36      144        6.944      150        6.666
1460	 37      148        6.756      150        6.666
1461	 38      152        6.578      175        5.714
1462	 39      156        6.410      175        5.714
1463	 40      160        6.250      175        5.714
1464	 41      164        6.097      175        5.714
1465	 42      168        5.952      175        5.714
1466	 43      172        5.813      175        5.714
1467	 44      176        5.681      187        5.333
1468	 45      180        5.555      187        5.333
1469	 46      184        5.434      187        5.333
1470	 47      188        5.319      200        5.000
1471	 48      192        5.208      200        5.000
1472	 49      196        5.102      200        5.000
1473	
1474	
1475	17. Serial NVRAM (added by Richard Waltham: dormouse@farsrobt.demon.co.uk)
1476	
1477	17.1 Features
1478	
1479	Enabling serial NVRAM support enables detection of the serial NVRAM included
1480	on Symbios and some Symbios compatible host adaptors, and Tekram boards. The 
1481	serial NVRAM is used by Symbios and Tekram to hold set up parameters for the 
1482	host adaptor and its attached drives.
1483	
1484	The Symbios NVRAM also holds data on the boot order of host adaptors in a
1485	system with more than one host adaptor. This enables the order of scanning
1486	the cards for drives to be changed from the default used during host adaptor
1487	detection.
1488	
1489	This can be done to a limited extent at the moment using "reverse probe" but
1490	this only changes the order of detection of different types of cards. The
1491	NVRAM boot order settings can do this as well as change the order the same
1492	types of cards are scanned in, something "reverse probe" cannot do.
1493	
1494	Tekram boards using Symbios chips, DC390W/F/U, which have NVRAM are detected
1495	and this is used to distinguish between Symbios compatible and Tekram host 
1496	adaptors. This is used to disable the Symbios compatible "diff" setting
1497	incorrectly set on Tekram boards if the CONFIG_SCSI_53C8XX_SYMBIOS_COMPAT 
1498	configuration parameter is set enabling both Symbios and Tekram boards to be 
1499	used together with the Symbios cards using all their features, including
1500	"diff" support. ("led pin" support for Symbios compatible cards can remain
1501	enabled when using Tekram cards. It does nothing useful for Tekram host
1502	adaptors but does not cause problems either.)
1503	
1504	
1505	17.2 Symbios NVRAM layout
1506	
1507	typical data at NVRAM address 0x100 (53c810a NVRAM)
1508	-----------------------------------------------------------
1509	00 00
1510	64 01
1511	8e 0b
1512	
1513	00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00 
1514	
1515	04 00 0f 00 00 10 00 50 00 00 01 00 00 62 
1516	04 00 03 00 00 10 00 58 00 00 01 00 00 63 
1517	04 00 01 00 00 10 00 48 00 00 01 00 00 61 
1518	00 00 00 00 00 00 00 00 00 00 00 00 00 00 
1519	
1520	0f 00 08 08 64 00 0a 00
1521	0f 00 08 08 64 00 0a 00 
1522	0f 00 08 08 64 00 0a 00 
1523	0f 00 08 08 64 00 0a 00 
1524	0f 00 08 08 64 00 0a 00 
1525	0f 00 08 08 64 00 0a 00 
1526	0f 00 08 08 64 00 0a 00 
1527	0f 00 08 08 64 00 0a 00 
1528	
1529	0f 00 08 08 64 00 0a 00 
1530	0f 00 08 08 64 00 0a 00 
1531	0f 00 08 08 64 00 0a 00 
1532	0f 00 08 08 64 00 0a 00 
1533	0f 00 08 08 64 00 0a 00 
1534	0f 00 08 08 64 00 0a 00 
1535	0f 00 08 08 64 00 0a 00 
1536	0f 00 08 08 64 00 0a 00 
1537	
1538	00 00 00 00 00 00 00 00 
1539	00 00 00 00 00 00 00 00 
1540	00 00 00 00 00 00 00 00 
1541	00 00 00 00 00 00 00 00 
1542	00 00 00 00 00 00 00 00 
1543	00 00 00 00 00 00 00 00 
1544	00 00 00 00 00 00 00 00 
1545	00 00 00 00 00 00 00 00 
1546	
1547	00 00 00 00 00 00 00 00 
1548	00 00 00 00 00 00 00 00 
1549	00 00 00 00 00 00 00 00 
1550	00 00 00 00 00 00 00 00 
1551	00 00 00 00 00 00 00 00 
1552	00 00 00 00 00 00 00 00 
1553	00 00 00 00 00 00 00 00 
1554	00 00 00 00 00 00 00 00 
1555	
1556	00 00 00 00 00 00 00 00 
1557	00 00 00 00 00 00 00 00 
1558	00 00 00 00 00 00 00 00 
1559	
1560	fe fe
1561	00 00
1562	00 00
1563	-----------------------------------------------------------
1564	NVRAM layout details
1565	
1566	NVRAM Address 0x000-0x0ff not used
1567	              0x100-0x26f initialised data
1568	              0x270-0x7ff not used
1569	
1570	general layout
1571	
1572	        header  -   6 bytes,
1573	        data    - 356 bytes (checksum is byte sum of this data)
1574	        trailer -   6 bytes
1575	                  ---
1576	        total     368 bytes
1577	
1578	data area layout
1579	
1580	        controller set up  -  20 bytes
1581	        boot configuration -  56 bytes (4x14 bytes)
1582	        device set up      - 128 bytes (16x8 bytes)
1583	        unused (spare?)    - 152 bytes (19x8 bytes)
1584	                             ---
1585	        total                356 bytes
1586	
1587	-----------------------------------------------------------
1588	header
1589	
1590	00 00   - ?? start marker
1591	64 01   - byte count (lsb/msb excludes header/trailer)
1592	8e 0b   - checksum (lsb/msb excludes header/trailer)
1593	-----------------------------------------------------------
1594	controller set up
1595	
1596	00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00
1597	                   |     |           |     |
1598	                   |     |           |      -- host ID
1599	                   |     |           |
1600	                   |     |            --Removable Media Support
1601	                   |     |               0x00 = none
1602	                   |     |               0x01 = Bootable Device
1603	                   |     |               0x02 = All with Media
1604	                   |     |
1605	                   |      --flag bits 2
1606	                   |        0x00000001= scan order hi->low
1607	                   |            (default 0x00 - scan low->hi)
1608	                    --flag bits 1
1609	                       0x00000001 scam enable
1610	                       0x00000010 parity enable
1611	                       0x00000100 verbose boot msgs
1612	
1613	remaining bytes unknown - they do not appear to change in my
1614	current set up for any of the controllers.
1615	
1616	default set up is identical for 53c810a and 53c875 NVRAM
1617	(Removable Media added Symbios BIOS version 4.09)
1618	-----------------------------------------------------------
1619	boot configuration
1620	
1621	boot order set by order of the devices in this table
1622	
1623	04 00 0f 00 00 10 00 50 00 00 01 00 00 62 -- 1st controller
1624	04 00 03 00 00 10 00 58 00 00 01 00 00 63    2nd controller
1625	04 00 01 00 00 10 00 48 00 00 01 00 00 61    3rd controller
1626	00 00 00 00 00 00 00 00 00 00 00 00 00 00    4th controller
1627	       |  |  |  |     |        |     |  |
1628	       |  |  |  |     |        |      ---- PCI io port adr
1629	       |  |  |  |     |         --0x01 init/scan at boot time
1630	       |  |  |  |      --PCI device/function number (0xdddddfff)
1631	       |  |   ----- ?? PCI vendor ID (lsb/msb)
1632	        ----PCI device ID (lsb/msb)
1633	
1634	?? use of this data is a guess but seems reasonable
1635	
1636	remaining bytes unknown - they do not appear to change in my
1637	current set up
1638	
1639	default set up is identical for 53c810a and 53c875 NVRAM
1640	-----------------------------------------------------------
1641	device set up (up to 16 devices - includes controller)
1642	
1643	0f 00 08 08 64 00 0a 00 - id 0
1644	0f 00 08 08 64 00 0a 00 
1645	0f 00 08 08 64 00 0a 00 
1646	0f 00 08 08 64 00 0a 00 
1647	0f 00 08 08 64 00 0a 00 
1648	0f 00 08 08 64 00 0a 00 
1649	0f 00 08 08 64 00 0a 00 
1650	0f 00 08 08 64 00 0a 00 
1651	
1652	0f 00 08 08 64 00 0a 00 
1653	0f 00 08 08 64 00 0a 00 
1654	0f 00 08 08 64 00 0a 00 
1655	0f 00 08 08 64 00 0a 00 
1656	0f 00 08 08 64 00 0a 00 
1657	0f 00 08 08 64 00 0a 00 
1658	0f 00 08 08 64 00 0a 00 
1659	0f 00 08 08 64 00 0a 00 - id 15
1660	 |     |  |  |     |  |
1661	 |     |  |  |      ----timeout (lsb/msb)
1662	 |     |  |   --synch period (0x?? 40 Mtrans/sec- fast 40) (probably 0x28)
1663	 |     |  |                  (0x30 20 Mtrans/sec- fast 20)
1664	 |     |  |                  (0x64 10 Mtrans/sec- fast )
1665	 |     |  |                  (0xc8  5 Mtrans/sec)
1666	 |     |  |                  (0x00  asynchronous)
1667	 |     |   -- ?? max sync offset (0x08 in NVRAM on 53c810a) 
1668	 |     |                         (0x10 in NVRAM on 53c875)
1669	 |      --device bus width (0x08 narrow)
1670	 |                         (0x10 16 bit wide)
1671	  --flag bits
1672	    0x00000001 - disconnect enabled
1673	    0x00000010 - scan at boot time
1674	    0x00000100 - scan luns
1675	    0x00001000 - queue tags enabled
1676	
1677	remaining bytes unknown - they do not appear to change in my
1678	current set up
1679	
1680	?? use of this data is a guess but seems reasonable 
1681	(but it could be max bus width)
1682	
1683	default set up for 53c810a NVRAM
1684	default set up for 53c875 NVRAM - bus width     - 0x10
1685	                                - sync offset ? - 0x10
1686	                                - sync period   - 0x30
1687	-----------------------------------------------------------
1688	?? spare device space (32 bit bus ??)
1689	
1690	00 00 00 00 00 00 00 00  (19x8bytes)
1691	.
1692	.
1693	00 00 00 00 00 00 00 00
1694	
1695	default set up is identical for 53c810a and 53c875 NVRAM
1696	-----------------------------------------------------------
1697	trailer
1698	
1699	fe fe   - ? end marker ?
1700	00 00
1701	00 00
1702	
1703	default set up is identical for 53c810a and 53c875 NVRAM
1704	-----------------------------------------------------------
1705	
1706	
1707	
1708	17.3 Tekram NVRAM layout
1709	
1710	nvram 64x16 (1024 bit)
1711	
1712	Drive settings
1713	
1714	Drive ID 0-15 (addr 0x0yyyy0 = device setup, yyyy = ID)
1715	              (addr 0x0yyyy1 = 0x0000)
1716	
1717	    x x x x  x x x x  x x x x  x x x x
1718	               | | |      | |  | | | |
1719	               | | |      | |  | | |  ----- parity check   0 - off
1720	               | | |      | |  | | |                       1 - on
1721	               | | |      | |  | | |
1722	               | | |      | |  | |  ------- sync neg       0 - off
1723	               | | |      | |  | |                         1 - on
1724	               | | |      | |  | |
1725	               | | |      | |  |  --------- disconnect     0 - off
1726	               | | |      | |  |                           1 - on
1727	               | | |      | |  |
1728	               | | |      | |   ----------- start cmd      0 - off
1729	               | | |      | |                              1 - on
1730	               | | |      | |
1731	               | | |      |  -------------- tagged cmds    0 - off
1732	               | | |      |                                1 - on
1733	               | | |      | 
1734	               | | |       ---------------- wide neg       0 - off
1735	               | | |                                       1 - on
1736	               | | |
1737	                --------------------------- sync rate      0 - 10.0 Mtrans/sec
1738	                                                           1 -  8.0
1739	                                                           2 -  6.6
1740	                                                           3 -  5.7
1741	                                                           4 -  5.0
1742	                                                           5 -  4.0
1743	                                                           6 -  3.0
1744	                                                           7 -  2.0
1745	                                                           7 -  2.0
1746	                                                           8 - 20.0
1747	                                                           9 - 16.7
1748	                                                           a - 13.9
1749	                                                           b - 11.9
1750	
1751	Global settings
1752	
1753	Host flags 0 (addr 0x100000, 32) 
1754	
1755	    x x x x  x x x x  x x x x  x x x x
1756	    | | | |  | | | |           | | | |
1757	    | | | |  | | | |            ----------- host ID    0x00 - 0x0f
1758	    | | | |  | | | |
1759	    | | | |  | | |  ----------------------- support for    0 - off
1760	    | | | |  | | |                          > 2 drives     1 - on
1761	    | | | |  | | | 
1762	    | | | |  | |  ------------------------- support drives 0 - off
1763	    | | | |  | |                            > 1Gbytes      1 - on
1764	    | | | |  | |
1765	    | | | |  |  --------------------------- bus reset on   0 - off
1766	    | | | |  |                                power on     1 - on
1767	    | | | |  |
1768	    | | | |   ----------------------------- active neg     0 - off
1769	    | | | |                                                1 - on
1770	    | | | |
1771	    | | |  -------------------------------- imm seek       0 - off
1772	    | | |                                                  1 - on
1773	    | | |
1774	    | |  ---------------------------------- scan luns      0 - off
1775	    | |                                                    1 - on
1776	    | |
1777	     -------------------------------------- removable      0 - disable
1778	                                            as BIOS dev    1 - boot device
1779	                                                           2 - all
1780	
1781	Host flags 1 (addr 0x100001, 33)
1782	
1783	    x x x x  x x x x  x x x x  x x x x
1784	               | | |             | | | 
1785	               | | |              --------- boot delay     0 -   3 sec
1786	               | | |                                       1 -   5
1787	               | | |                                       2 -  10
1788	               | | |                                       3 -  20
1789	               | | |                                       4 -  30
1790	               | | |                                       5 -  60
1791	               | | |                                       6 - 120
1792	               | | |
1793	                --------------------------- max tag cmds   0 -  2
1794	                                                           1 -  4
1795	                                                           2 -  8
1796	                                                           3 - 16
1797	                                                           4 - 32
1798	
1799	Host flags 2 (addr 0x100010, 34)
1800	
1801	    x x x x  x x x x  x x x x  x x x x
1802	                                     |
1803	                                      ----- F2/F6 enable   0 - off ???
1804	                                                           1 - on  ???
1805	
1806	checksum (addr 0x111111)
1807	
1808	checksum = 0x1234 - (sum addr 0-63)
1809	
1810	----------------------------------------------------------------------------
1811	
1812	default nvram data:
1813	
1814	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
1815	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
1816	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
1817	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 
1818	
1819	0x0f07 0x0400 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000
1820	0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
1821	0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
1822	0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0xfbbc
1823	
1824	
1825	18. Support for Big Endian
1826	
1827	The PCI local bus has been primarily designed for x86 architecture.
1828	As a consequence, PCI devices generally expect DWORDS using little endian 
1829	byte ordering.
1830	
1831	18.1 Big Endian CPU
1832	
1833	In order to support NCR chips on a Big Endian architecture the driver has to 
1834	perform byte reordering each time it is needed. This feature has been 
1835	added to the driver by Cort <cort@cs.nmt.edu> and is available in driver 
1836	version 2.5 and later ones. For the moment Big Endian support has only 
1837	been tested on Linux/PPC (PowerPC).
1838	
1839	18.2 NCR chip in Big Endian mode of operations
1840	
1841	It can be read in SYMBIOS documentation that some chips support a special 
1842	Big Endian mode, on paper: 53C815, 53C825A, 53C875, 53C875N, 53C895.
1843	This mode of operations is not software-selectable, but needs pin named 
1844	BigLit to be pulled-up. Using this mode, most of byte reorderings should 
1845	be avoided when the driver is running on a Big Endian CPU.
1846	Driver version 2.5 is also, in theory, ready for this feature.
1847	
1848	===============================================================================
1849	End of NCR53C8XX driver README file
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