1The tmscsim driver
2==================
3
41. Purpose and history
52. Installation
63. Features
74. Configuration via /proc/scsi/tmscsim/?
85. Configuration via boot/module params
96. Potential improvements
107. Bug reports, debugging and updates
118. Acknowledgements
129. Copyright
13
14
151. Purpose and history
16----------------------
17The tmscsim driver supports PCI SCSI Host Adapters based on the AM53C974
18chip. AM53C974 based SCSI adapters include: 
19 Tekram DC390, DC390T
20 Dawicontrol 2974
21 QLogic Fast! PCI Basic
22 some on-board adapters
23(This is most probably not a complete list)
24
25It has originally written by C.L. Huang from the Tekram corp. to support the
26Tekram DC390(T) adapter. This is where the name comes from: tm = Tekram
27scsi = SCSI driver, m = AMD (?) as opposed to w for the DC390W/U/F
28(NCR53c8X5, X=2/7) driver. Yes, there was also a driver for the latter,
29tmscsiw, which supported DC390W/U/F adapters. It's not maintained any more,
30as the ncr53c8xx is perfectly supporting these adapters since some time.
31
32The driver first appeared in April 1996, exclusively supported the DC390 
33and has been enhanced since then in various steps. In May 1998 support for 
34general AM53C974 based adapters and some possibilities to configure it were
35added. The non-DC390 support works by assuming some values for the data
36normally taken from the DC390 EEPROM. See below (chapter 5) for details.
37
38When using the DC390, the configuration is still be done using the DC390
39BIOS setup. The DC390 EEPROM is read and used by the driver, any boot or
40module parameters (chapter 5) are ignored! However, you can change settings
41dynamically, as described in chapter 4. 
42
43For a more detailed description of the driver's history, see the first lines
44of tmscsim.c.
45The numbering scheme isn't consistent. The first versions went from 1.00 to
461.12, then 1.20a to 1.20t. Finally I decided to use the ncr53c8xx scheme. So
47the next revisions will be 2.0a to 2.0X (stable), 2.1a to 2.1X (experimental),
482.2a to 2.2X (stable, again) etc. (X = anything between a and z.) If I send
49fixes to people for testing, I create intermediate versions with a digit 
50appended, e.g. 2.0c3.
51
52
532. Installation
54---------------
55If you got any recent kernel with this driver and document included in
56linux/drivers/scsi, you basically have to do nothing special to use this
57driver. Of course you have to choose to compile SCSI support and DC390(T)
58support into your kernel or as module when configuring your kernel for
59compiling.
60NEW: You may as well compile this module outside your kernel, using the
61supplied Makefile.
62
63 If you got an old kernel (pre 2.1.127, pre 2.0.37p1) with an old version of
64 this driver: Get dc390-21125-20b.diff.gz or dc390-2036p21-20b1.diff.gz from
65 my web page and apply the patch. Apply further patches to upgrade to the 
66 latest version of the driver.
67
68 If you want to do it manually, you should copy the files (dc390.h,
69 tmscsim.h, tmscsim.c, scsiiom.c and README.tmscsim) from this directory to
70 linux/drivers/scsi. You have to recompile your kernel/module of course.
71
72 You should apply the three patches included in dc390-120-kernel.diff
73 (Applying them: cd /usr/src; patch -p0 <~/dc390-120-kernel.diff)
74 The patches are against 2.1.125, so you might have to manually resolve
75 rejections when applying to another kernel version.
76
77 The patches will update the kernel startup code to allow boot parameters to
78 be passed to the driver, update the Documentation and finally offer you the
79 possibility to omit the non-DC390 parts of the driver.
80 (By selecting "Omit support for non DC390" you basically disable the
81 emulation of a DC390 EEPROM for non DC390 adapters. This saves a few bytes
82 of memory.)
83
84If you got a very old kernel without the tmscsim driver (pre 2.0.31)
85I recommend upgrading your kernel. However, if you don't want to, please
86contact me to get the appropriate patches.
87
88
89Upgrading a SCSI driver is always a delicate thing to do. The 2.0 driver has
90proven stable on many systems, but it's still a good idea to take some
91precautions. In an ideal world you would have a full backup of your disks.
92The world isn't ideal and most people don't have full backups (me neither).
93So take at least the following measures:
94* make your kernel remount the FS read-only on detecting an error:
95  tune2fs -e remount-ro /dev/sd??
96* have copies of your SCSI disk's partition tables on some safe location:
97  dd if=/dev/sda of=/mnt/floppy/sda bs=512 count=1
98  or just print it with:
99  fdisk -l | lpr
100* make sure you are able to boot Linux (e.g. from floppy disk using InitRD)
101  if your SCSI disk gets corrupted. You can use 
102  ftp://student.physik.uni-dortmund.de/pub/linux/kernel/bootdisk.gz
103
104One more warning: I used to overclock my PCI bus to 41.67 MHz. My Tekram
105DC390F (Sym53c875) accepted this as well as my Millennium. But the Am53C974
106produced errors and started to corrupt my disks. So don't do that! A 37.50
107MHz PCI bus works for me, though, but I don't recommend using higher clocks
108than the 33.33 MHz being in the PCI spec.
109
110
1113.Features
112----------
113- SCSI
114 * Tagged command queueing
115 * Sync speed up to 10 MHz
116 * Disconnection
117 * Multiple LUNs
118
119- General / Linux interface
120 * Support for up to 4 AM53C974 adapters.
121 * DC390 EEPROM usage or boot/module params
122 * Information via cat /proc/scsi/tmscsim/?
123 * Dynamically configurable by writing to /proc/scsi/tmscsim/?
124 * Dynamic allocation of resources
125 * SMP support: Locking on io_request lock (Linux 2.1/2.2) or adapter 
126    specific locks (Linux 2.5?)
127 * Uniform source code for Linux-2.x.y
128 * Support for dyn. addition/removal of devices via add/remove-single-device
129   (Try: echo "scsi add-single-device C B T U" >/proc/scsi/scsi 
130    C = Controller, B = Bus, T = Target SCSI ID, U = Unit SCSI LUN.) 
131    Use with care!
132 * Try to use the partition table for the determination of the mapping
133
134
1354. Configuration via /proc/scsi/tmscsim/?
136-----------------------------------------
137First of all look at the output of /proc/scsi/tmscsim/? by typing
138 cat /proc/scsi/tmscsim/?
139The "?" should be replaced by the SCSI host number. (The shell might do this
140for you.)
141You will see some info regarding the adapter and, at the end, a listing of
142the attached devices and their settings.
143
144Here's an example:
145garloff@kurt:/home/garloff > cat /proc/scsi/tmscsim/0
146Tekram DC390/AM53C974 PCI SCSI Host Adapter, Driver Version 2.0e7 2000-11-28
147SCSI Host Nr 1, AM53C974 Adapter Nr 0
148IOPortBase 0xb000, IRQ 10
149MaxID 8, MaxLUN 8, AdapterID 6, SelTimeout 250 ms, DelayReset 1 s
150TagMaxNum 16, Status 0x00, ACBFlag 0x00, GlitchEater 24 ns
151Statistics: Cmnds 1470165, Cmnds not sent directly 0, Out of SRB conds 0
152            Lost arbitrations 587,  Sel. connected 0, Connected: No
153Nr of attached devices: 4, Nr of DCBs: 4
154Map of attached LUNs: 01 00 00 03 01 00 00 00
155Idx ID LUN Prty Sync DsCn SndS TagQ NegoPeriod SyncSpeed SyncOffs MaxCmd
15600  00  00  Yes  Yes  Yes  Yes  Yes   100 ns    10.0 M      15      16
15701  03  00  Yes  Yes  Yes  Yes  No    100 ns    10.0 M      15      01
15802  03  01  Yes  Yes  Yes  Yes  No    100 ns    10.0 M      15      01
15903  04  00  Yes  Yes  Yes  Yes  No    100 ns    10.0 M      15      01
160
161Note that the settings MaxID and MaxLUN are not zero- but one-based, which
162means that a setting MaxLUN=4, will result in the support of LUNs 0..3. This
163is somehow inconvenient, but the way the mid-level SCSI code expects it to be.
164
165ACB and DCB are acronyms for Adapter Control Block and Device Control Block.
166These are data structures of the driver containing information about the
167adapter and the connected SCSI devices respectively.
168
169Idx is the device index (just a consecutive number for the driver), ID and
170LUN are the SCSI ID and LUN, Prty means Parity checking, Sync synchronous
171negotiation, DsCn Disconnection, SndS Send Start command on startup (not
172used by the driver) and TagQ Tagged Command Queueing. NegoPeriod and
173SyncSpeed are somehow redundant, because they are reciprocal values 
174(1 / 112 ns = 8.9 MHz). At least in theory. The driver is able to adjust the
175NegoPeriod more accurate (4ns) than the SyncSpeed (1 / 25ns). I don't know
176if certain devices will have problems with this discrepancy. Max. speed is
17710 MHz corresp. to a min. NegoPeriod of 100 ns. 
178(The driver allows slightly higher speeds if the devices (Ultra SCSI) accept
179it, but that's out of adapter spec, on your own risk and unlikely to improve
180performance. You're likely to crash your disks.) 
181SyncOffs is the offset used for synchronous negotiations; max. is 15. 
182The last values are only shown, if Sync is enabled. (NegoPeriod is still
183displayed in brackets to show the values which will be used after enabling
184Sync.)
185MaxCmd ist the number of commands (=tags) which can be processed at the same
186time by the device.
187
188If you want to change a setting, you can do that by writing to
189/proc/scsi/tmscsim/?. Basically you have to imitate the output of driver.
190(Don't use the brackets for NegoPeriod on Sync disabled devices.)
191You don't have to care about capitalisation. The driver will accept space,
192tab, comma, = and : as separators.
193
194There are three kinds of changes: 
195
196(1) Change driver settings: 
197    You type the names of the parameters and the params following it.
198    Example:
199     echo "MaxLUN=8 seltimeout 200" >/proc/scsi/tmscsim/0
200
201    Note that you can only change MaxID, MaxLUN, AdapterID, SelTimeOut,
202    TagMaxNum, ACBFlag, GlitchEater and DelayReset. Don't change ACBFlag
203    unless you want to see what happens, if the driver hangs.
204
205(2) Change device settings: You write a config line to the driver. The Nr
206    must match the ID and LUN given. If you give "-" as parameter, it is
207    ignored and the corresponding setting won't be changed. 
208    You can use "y" or "n" instead of "Yes" and "No" if you want to.
209    You don't need to specify a full line. The driver automatically performs
210    an INQUIRY on the device if necessary to check if it is capable to operate
211    with the given settings (Sync, TagQ).
212    Examples:
213     echo "0 0 0 y y y - y - 10 " >/proc/scsi/tmscsim/0
214     echo "3 5 0 y n y " >/proc/scsi/tmscsim/0
215
216    To give a short explanation of the first example: 
217    The first three numbers, "0 0 0" (Device index 0, SCSI ID 0, SCSI LUN 0),
218    select the device to which the following parameters apply. Note that it
219    would be sufficient to use the index or both SCSI ID and LUN, but I chose
220    to require all three to have a syntax similar to the output.
221    The following "y y y - y" enables Parity checking, enables Synchronous
222    transfers, Disconnection, leaves Send Start (not used) untouched and
223    enables Tagged Command Queueing for the selected device. The "-" skips
224    the Negotiation Period setting but the "10" sets the max sync. speed to
225    10 MHz. It's useless to specify both NegoPeriod and SyncSpeed as
226    discussed above. The values used in this example will result in maximum
227    performance.
228
229(3) Special commands: You can force a SCSI bus reset, an INQUIRY command, the
230    removal or the addition of a device's DCB and a SCSI register dump.
231    This is only used for debugging when you meet problems. The parameter of
232    the INQUIRY and REMOVE commands is the device index as shown by the
233    output of /proc/scsi/tmscsim/? in the device listing in the first column
234    (Idx). ADD takes the SCSI ID and LUN.
235    Examples:
236     echo "reset" >/proc/scsi/tmscsim/0
237     echo "inquiry 1" >/proc/scsi/tmscsim/0
238     echo "remove 2" >/proc/scsi/tmscsim/1
239     echo "add 2 3" >/proc/scsi/tmscsim/?
240     echo "dump" >/proc/scsi/tmscsim/0
241
242    Note that you will meet problems when you REMOVE a device's DCB with the
243    remove command if it contains partitions which are mounted. Only use it
244    after unmounting its partitions, telling the SCSI mid-level code to
245    remove it (scsi remove-single-device) and you really need a few bytes of
246    memory.
247    The ADD command allows you to configure a device before you tell the
248    mid-level code to try detection.
249
250
251I'd suggest reviewing the output of /proc/scsi/tmscsim/? after changing
252settings to see if everything changed as requested.
253
254
2555. Configuration via boot/module parameters
256-------------------------------------------
257With the DC390, the driver reads its EEPROM settings and tries to use them.
258But you may want to override the settings prior to being able to change the
259driver configuration via /proc/scsi/tmscsim/?.
260If you do have another AM53C974 based adapter, that's even the only
261possibility to adjust settings before you are able to write to the
262/proc/scsi/tmscsim/? pseudo-file, e.g. if you want to use another 
263adapter ID than 7.  
264(BTW, the log message "DC390: No EEPROM found!" is normal without a DC390.)
265For this purpose, you can pass options to the driver before it is initialised
266by using kernel or module parameters. See lilo(8) or modprobe(1) manual
267pages on how to pass params to the kernel or a module.
268[NOTE: Formerly, it was not possible to override the EEPROM supplied
269 settings of the DC390 with cmd line parameters. This has changed since
270 2.0e7]
271
272The syntax of the params is much shorter than the syntax of the /proc/...
273interface. This makes it a little bit more difficult to use. However, long
274parameter lines have the risk to be misinterpreted and the length of kernel
275parameters is limited.
276
277As the support for non-DC390 adapters works by simulating the values of the
278DC390 EEPROM, the settings are given in a DC390 BIOS' way.
279
280Here's the syntax:
281tmscsim=AdaptID,SpdIdx,DevMode,AdaptMode,TaggedCmnds,DelayReset
282
283Each of the parameters is a number, containing the described information:
284
285* AdaptID: The SCSI ID of the host adapter. Must be in the range 0..7
286  Default is 7.
287
288* SpdIdx: The index of the maximum speed as in the DC390 BIOS. The values
289  0..7 mean 10, 8.0, 6.7, 5.7, 5.0, 4.0, 3.1 and 2 MHz resp. Default is
290  0 (10.0 MHz).
291
292* DevMode is a bit mapped value describing the per-device features. It
293  applies to all devices. (Sync, Disc and TagQ will only apply, if the
294  device supports it.) The meaning of the bits (* = default):
295
296   Bit Val(hex) Val(dec)  Meaning
297   *0	 0x01	    1	  Parity check
298   *1	 0x02	    2	  Synchronous Negotiation
299   *2	 0x04	    4	  Disconnection
300   *3	 0x08	    8	  Send Start command on startup. (Not used)
301   *4	 0x10	   16	  Tagged Command Queueing
302
303  As usual, the desired value is obtained by adding the wanted values. If
304  you want to enable all values, e.g., you would use 31(0x1f). Default is 31.
305
306* AdaptMode is a bit mapped value describing the enabled adapter features.
307
308   Bit Val(hex) Val(dec)  Meaning
309   *0	 0x01	    1	  Support more than two drives. (Not used)
310   *1	 0x02	    2	  Use DOS compatible mapping for HDs greater than 1GB.
311   *2	 0x04	    4	  Reset SCSI Bus on startup.
312   *3	 0x08	    8	  Active Negation: Improves SCSI Bus noise immunity.
313    4	 0x10	   16	  Immediate return on BIOS seek command. (Not used)
314 (*)5	 0x20	   32	  Check for LUNs >= 1.
315  
316* TaggedCmnds is a number indicating the maximum number of Tagged Commands.
317  It is the binary logarithm - 1 of the actual number. Max is 4 (32).
318   Value  Number of Tagged Commands
319     0		 2
320     1		 4
321     2		 8
322    *3		16
323     4		32
324
325* DelayReset is the time in seconds (minus 0.5s), the adapter waits, after a
326  bus reset. Default is 1 (corresp. to 1.5s).
327
328Example:
329 modprobe tmscsim tmscsim=6,2,31
330would set the adapter ID to 6, max. speed to 6.7 MHz, enable all device
331features and leave the adapter features, the number of Tagged Commands
332and the Delay after a reset to the defaults.
333
334As you can see, you don't need to specify all of the six params.
335If you want values to be ignored (i.e. the EEprom settings or the defaults
336will be used), you may pass -2 (not 0!) at the corresponding position.
337
338The defaults (7,0,31,15,3,1) are aggressive to allow good performance. You
339can use tmscsim=7,0,31,63,4,0 for maximum performance, if your SCSI chain
340allows it. If you meet problems, you can use tmscsim=-1 which is a shortcut
341for tmscsim=7,4,9,15,2,10.
342
343
3446. Potential improvements
345-------------------------
346Most of the intended work on the driver has been done. Here are a few ideas
347to further improve its usability:
348
349* Cleanly separate per-Target and per-LUN properties (DCB)
350* More intelligent abort() routine
351* Use new_eh code (Linux-2.1+)
352* Have the mid-level (ML) code (and not the driver) handle more of the
353  various conditions.
354* Command queueing in the driver: Eliminate Query list and use ML instead.
355* More user friendly boot/module param syntax
356
357Further investigation on these problems:
358
359* Driver hangs with sync readcdda (xcdroast) (most probably VIA PCI error)
360
361Known problems: 
362Please see http://www.garloff.de/kurt/linux/dc390/problems.html
363
364* Changing the parameters of multi-lun by the tmscsim/? interface will
365  cause problems, cause these settings are mostly per Target and not per LUN
366  and should be updated accordingly. To be fixed for 2.0d24.
367* CDRs (eg Yam CRW4416) not recognized, because some buggy devices don't 
368  recover from a SCSI reset in time. Use a higher delay or don't issue
369  a SCSI bus reset on driver initialization. See problems page.
370  For the CRW4416S, this seems to be solved with firmware 1.0g (reported by 
371  Jean-Yves Barbier).
372* TEAC CD-532S not being recognized. (Works with 1.11).
373* Scanners (eg. Astra UMAX 1220S) don't work: Disable Sync Negotiation.
374  If this does not help, try echo "INQUIRY t" >/proc/scsi/tmscsim/? (t
375  replaced by the dev index of your scanner). You may try to reset your SCSI
376  bus afterwards (echo "RESET" >/proc/scsi/tmscsim/?).
377  The problem seems to be solved as of 2.0d18, thanks to Andreas Rick.
378* If there is a valid partition table, the driver will use it for determining
379  the mapping. If there's none, a reasonable mapping (Symbios-like) will be
380  assumed. Other operating systems may not like this mapping, though
381  it's consistent with the BIOS' behaviour. Old DC390 drivers ignored the
382  partition table and used a H/S = 64/32 or 255/63 translation. So if you
383  want to be compatible to those, use this old mapping when creating
384  partition tables. Even worse, on bootup the DC390 might complain if other
385  mappings are found, so auto rebooting may fail.
386* In some situations, the driver will get stuck in an abort loop. This is a
387  bad interaction between the Mid-Layer of Linux' SCSI code and the driver.
388  Try to disable DsCn, if you meet this problem. Please contact me for
389  further debugging.
390
391
3927. Bug reports, debugging and updates
393-------------------------------------
394Whenever you have problems with the driver, you are invited to ask the
395author for help. However, I'd suggest reading the docs and trying to solve
396the problem yourself, first. 
397If you find something, which you believe to be a bug, please report it to me. 
398Please append the output of /proc/scsi/scsi, /proc/scsi/tmscsim/? and
399maybe the DC390 log messages to the report. 
400
401Bug reports should be send to me (Kurt Garloff <dc390@garloff.de>) as well
402as to the linux-scsi list (<linux-scsi@vger.kernel.org>), as sometimes bugs
403are caused by the SCSI mid-level code.
404
405I will ask you for some more details and probably I will also ask you to
406enable some of the DEBUG options in the driver (tmscsim.c:DC390_DEBUGXXX
407defines). The driver will produce some data for the syslog facility then.
408Beware: If your syslog gets written to a SCSI disk connected to your
409AM53C974, the logging might produce log output again, and you might end
410having your box spending most of its time doing the logging.
411
412The latest version of the driver can be found at:
413 http://www.garloff.de/kurt/linux/dc390/
414 ftp://ftp.suse.com/pub/people/garloff/linux/dc390/
415
416
4178. Acknowledgements
418-------------------
419Thanks to Linus Torvalds, Alan Cox, the FSF people, the XFree86 team and 
420all the others for the wonderful OS and software.
421Thanks to C.L. Huang and Philip Giang (Tekram) for the initial driver
422release and support.
423Thanks to Doug Ledford, Gérard Roudier for support with SCSI coding.
424Thanks to a lot of people (espec. Chiaki Ishikawa, Andreas Haumer, Hubert 
425Tonneau) for intensively testing the driver (and even risking data loss
426doing this during early revisions).
427Recently, SuSE GmbH, Nuernberg, FRG, has been paying me for the driver
428development and maintenance. Special thanks!
429
430
4319. Copyright
432------------
433 This driver is free software; you can redistribute it and/or modify
434 it under the terms of the GNU General Public License as published by   
435 the Free Software Foundation; version 2 of the License.
436 If you want to use any later version of the GNU GPL, you will probably
437 be allowed to, but you have to ask me and Tekram <erich@tekram.com.tw>
438 before.
439
440-------------------------------------------------------------------------
441Written by Kurt Garloff <kurt@garloff.de> 1998/06/11
442Last updated 2000/11/28, driver revision 2.0e7
443$Id: README.tmscsim,v 2.25.2.7 2000/12/20 01:07:12 garloff Exp $
444