drivers/block/cciss_scsi.h

   1 /*
   2  *    Disk Array driver for Compaq SA53xx Controllers, SCSI Tape module
   3  *    Copyright 2001 Compaq Computer Corporation
   4  *
   5  *    This program is free software; you can redistribute it and/or modify
   6  *    it under the terms of the GNU General Public License as published by
   7  *    the Free Software Foundation; either version 2 of the License, or
   8  *    (at your option) any later version.
   9  *
  10  *    This program is distributed in the hope that it will be useful,
  11  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *    MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  13  *    NON INFRINGEMENT.  See the GNU General Public License for more details.
  14  *
  15  *    You should have received a copy of the GNU General Public License
  16  *    along with this program; if not, write to the Free Software
  17  *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  *
  19  *    Questions/Comments/Bugfixes to iss_storagedev@hp.com
  20  *
  21  */
  22 #ifdef CONFIG_CISS_SCSI_TAPE
  23 #ifndef _CCISS_SCSI_H_
  24 #define _CCISS_SCSI_H_
  25
  26 #include <scsi/scsicam.h> /* possibly irrelevant, since we don't show disks */
  27
  28                 // the scsi id of the adapter...
  29 #define SELF_SCSI_ID 15
  30                 // 15 is somewhat arbitrary, since the scsi-2 bus
  31                 // that's presented by the driver to the OS is
  32                 // fabricated.  The "real" scsi-3 bus the
  33                 // hardware presents is fabricated too.
  34                 // The actual, honest-to-goodness physical
  35                 // bus that the devices are attached to is not
  36                 // addressible natively, and may in fact turn
  37                 // out to be not scsi at all.
  38
  39 #define SCSI_CCISS_CAN_QUEUE 2
  40
  41 /*
  42
  43 Note, cmd_per_lun could give us some trouble, so I'm setting it very low.
  44 Likewise, SCSI_CCISS_CAN_QUEUE is set very conservatively.
  45
  46 If the upper scsi layer tries to track how many commands we have
  47 outstanding, it will be operating under the misapprehension that it is
  48 the only one sending us requests.  We also have the block interface,
  49 which is where most requests must surely come from, so the upper layer's
  50 notion of how many requests we have outstanding will be wrong most or
  51 all of the time.
  52
  53 Note, the normal SCSI mid-layer error handling doesn't work well
  54 for this driver because 1) it takes the io_request_lock before
  55 calling error handlers and uses a local variable to store flags,
  56 so the io_request_lock cannot be released and interrupts enabled
  57 inside the error handlers, and, the error handlers cannot poll
  58 for command completion because they might get commands from the
  59 block half of the driver completing, and not know what to do
  60 with them.  That's what we get for making a hybrid scsi/block
  61 driver, I suppose.
  62
  63 */
  64
  65 struct cciss_scsi_dev_t {
  66         int devtype;
  67         int bus, target, lun;           /* as presented to the OS */
  68         unsigned char scsi3addr[8];     /* as presented to the HW */
  69 };
  70
  71 struct cciss_scsi_hba_t {
  72         char *name;
  73         int ndevices;
  74 #define CCISS_MAX_SCSI_DEVS_PER_HBA 16
  75         struct cciss_scsi_dev_t dev[CCISS_MAX_SCSI_DEVS_PER_HBA];
  76 };
  77
  78 #endif /* _CCISS_SCSI_H_ */
  79 #endif /* CONFIG_CISS_SCSI_TAPE */