scsi.c

<Linux1.0核心游记>电子书+书后源码+Linux1.0源码

/*
 *	scsi.c Copyright (C) 1992 Drew Eckhardt 
 *	generic mid-level SCSI driver by
 *		Drew Eckhardt 
 *
 *	<[e-mail]>
 *
 *	Bug correction thanks go to : 
 *		Rik Faith <[e-mail]>
 *		Tommy Thorn <tthorn>
 *		Thomas Wuensche <[e-mail]>
 * 
 *       Modified by Eric Youngdale [e-mail] to
 *       add scatter-gather, multiple outstanding request, and other
 *       enhancements.
 */

#include <asm/system.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>

#include "../block/blk.h"
#include "scsi.h"
#include "hosts.h"
#include "constants.h"

/*
static const char RCSid[] = "$Header: /usr/src/linux/kernel/blk_drv/scsi/RCS/scsi.c,v 1.5 1993/09/24 12:45:18 drew Exp drew $";
*/

/* Command groups 3 and 4 are reserved and should never be used.  */
const unsigned char scsi_command_size[8] = { 6, 10, 10, 12, 12, 12, 10, 10 };

#define INTERNAL_ERROR (panic ("Internal error in file %s, line %d.\n", __FILE__, __LINE__))

static void scsi_done (Scsi_Cmnd *SCpnt);
static int update_timeout (Scsi_Cmnd *, int);
static void print_inquiry(unsigned char *data);
static void scsi_times_out (Scsi_Cmnd * SCpnt);

static int time_start;
static int time_elapsed;

#define MAX_SCSI_DEVICE_CODE 10
const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE] =
{
 "Direct-Access    ",
 "Sequential-Access",
 "Printer          ",
 "Processor        ",
 "WORM             ",
 "CD-ROM           ",
 "Scanner          ",
 "Optical Device   ",
 "Medium Changer   ",
 "Communications   "
};


/*
	global variables : 
	NR_SCSI_DEVICES is the number of SCSI devices we have detected, 
	scsi_devices an array of these specifing the address for each 
	(host, id, LUN)
*/
	
int NR_SCSI_DEVICES=0;

Scsi_Device * scsi_devices = NULL;

static unsigned char generic_sense[6] = {REQUEST_SENSE, 0,0,0, 255, 0};

/* We make this not static so that we can read the array with gdb. */
/* static */ Scsi_Cmnd * last_cmnd = NULL;

/*
 *	As the scsi do command functions are inteligent, and may need to 
 *	redo a command, we need to keep track of the last command 
 *	executed on each one.
 */

#define WAS_RESET 	0x01
#define WAS_TIMEDOUT 	0x02
#define WAS_SENSE	0x04
#define IS_RESETTING	0x08
#define ASKED_FOR_SENSE 0x10
/* #define NEEDS_JUMPSTART 0x20  defined in hosts.h */

/*
 *	This is the number  of clock ticks we should wait before we time out 
 *	and abort the command.  This is for  where the scsi.c module generates 
 *	the command, not where it originates from a higher level, in which
 *	case the timeout is specified there.
 *
 *	ABORT_TIMEOUT and RESET_TIMEOUT are the timeouts for RESET and ABORT
 *	respectively.
 */

#ifdef DEBUG
	#define SCSI_TIMEOUT 500
#else
	#define SCSI_TIMEOUT 100
#endif

#ifdef DEBUG
	#define SENSE_TIMEOUT SCSI_TIMEOUT
	#define ABORT_TIMEOUT SCSI_TIMEOUT
	#define RESET_TIMEOUT SCSI_TIMEOUT
#else
	#define SENSE_TIMEOUT 50
	#define RESET_TIMEOUT 50
	#define ABORT_TIMEOUT 50
	#define MIN_RESET_DELAY 100
#endif

/* The following devices are known not to tolerate a lun != 0 scan for
   one reason or another.  Some will respond to all luns, others will
   lock up. */

     struct blist{
       char * vendor;
       char * model;
       char * revision; /* Latest revision known to be bad.  Not used yet */
     };

static struct blist blacklist[] = 
{
   {"DENON","DRD-25X","V"},   /* A cdrom that locks up when probed at lun != 0 */
   {"IMS", "CDD521/10","2.06"},   /* Locks-up when LUN>0 polled. */
   {"MAXTOR","XT-3280","PR02"},   /* Locks-up when LUN>0 polled. */
   {"MAXTOR","XT-4380S","B3C"},   /* Locks-up when LUN>0 polled. */
   {"MAXTOR","MXT-1240S","I1.2"}, /* Locks up when LUN > 0 polled */
   {"MAXTOR","XT-4170S","B5A"},   /* Locks-up sometimes when LUN>0 polled. */
   {"MAXTOR","XT-8760S","B7B"},   /* guess what? */
   {"NEC","CD-ROM DRIVE:841","1.0"},  /* Locks-up when LUN>0 polled. */
   {"RODIME","RO3000S","2.33"},  /* Locks up if polled for lun != 0 */
   {"SEAGATE", "ST157N", "\004|j"}, /* causes failed REQUEST SENSE on lun 1 for aha152x
				     * controller, which causes SCSI code to reset bus.*/
   {"SEAGATE", "ST296","921"},   /* Responds to all lun */
   {"SONY","CD-ROM CDU-541","4.3d"},
   {"TANDBERG","TDC 3600","U07"},  /* Locks up if polled for lun != 0 */
   {"TEAC","CD-ROM","1.06"},	/* causes failed REQUEST SENSE on lun 1 for seagate
				 * controller, which causes SCSI code to reset bus.*/
   {"TEXEL","CD-ROM","1.06"},   /* causes failed REQUEST SENSE on lun 1 for seagate
				 * controller, which causes SCSI code to reset bus.*/
   {NULL, NULL, NULL}};	

static int blacklisted(unsigned char * response_data){
  int i = 0;
  unsigned char * pnt;
  for(i=0; 1; i++){
    if(blacklist[i].vendor == NULL) return 0;
    pnt = &response_data[8];
    while(*pnt && *pnt == ' ') pnt++;
    if(memcmp(blacklist[i].vendor, pnt,
	       strlen(blacklist[i].vendor))) continue;
    pnt = &response_data[16];
    while(*pnt && *pnt == ' ') pnt++;
    if(memcmp(blacklist[i].model, pnt,
	       strlen(blacklist[i].model))) continue;
    return 1;
  };	
};

/*
 *	As the actual SCSI command runs in the background, we must set up a 
 *	flag that tells scan_scsis() when the result it has is valid.  
 *	scan_scsis can set the_result to -1, and watch for it to become the 
 *	actual return code for that call.  the scan_scsis_done function() is 
 *	our user specified completion function that is passed on to the  
 *	scsi_do_cmd() function.
 */

static volatile int in_scan = 0;
static int the_result;
static void scan_scsis_done (Scsi_Cmnd * SCpnt)
	{
	
#ifdef DEBUG
	printk ("scan_scsis_done(%d, %06x)\n", SCpnt->host, SCpnt->result);
#endif	
	SCpnt->request.dev = 0xfffe;
	}
/*
 *	Detecting SCSI devices :	
 *	We scan all present host adapter's busses,  from ID 0 to ID 6.  
 *	We use the INQUIRY command, determine device type, and pass the ID / 
 *	lun address of all sequential devices to the tape driver, all random 
 *	devices to the disk driver.
 */

static void scan_scsis (void)
{
  int dev, lun, type;
  unsigned char scsi_cmd [12];
  unsigned char scsi_result [256];
  struct Scsi_Host * shpnt;
  Scsi_Cmnd  SCmd;
  
  ++in_scan;
  lun = 0;
  
  SCmd.next = NULL;
  SCmd.prev = NULL;
  for (shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
      {
	shpnt->host_queue = &SCmd;  /* We need this so that
					 commands can time out */
	for (dev = 0; dev < 8; ++dev)
	  if (shpnt->this_id != dev)
/*
 * We need the for so our continue, etc. work fine.
 */

#ifdef NO_MULTI_LUN
	    for (lun = 0; lun < 1; ++lun)
#else
	    for (lun = 0; lun < 8; ++lun)
#endif
	      {
		scsi_devices[NR_SCSI_DEVICES].host = shpnt;
		scsi_devices[NR_SCSI_DEVICES].id = dev;
		scsi_devices[NR_SCSI_DEVICES].lun = lun;
		scsi_devices[NR_SCSI_DEVICES].index = NR_SCSI_DEVICES;
		scsi_devices[NR_SCSI_DEVICES].device_wait = NULL;
/*
 * Assume that the device will have handshaking problems, and then 
 * fix this field later if it turns out it doesn't.
 */
		scsi_devices[NR_SCSI_DEVICES].borken = 1;
		
		scsi_cmd[0] = TEST_UNIT_READY;
		scsi_cmd[1] = lun << 5;
		scsi_cmd[2] = scsi_cmd[3] = scsi_cmd[5] = 0;
		scsi_cmd[4] = 0;

		SCmd.host = shpnt;
		SCmd.target = dev;
		SCmd.lun = lun;

		SCmd.request.dev = 0xffff; /* Mark not busy */
		SCmd.use_sg  = 0;
		SCmd.old_use_sg  = 0;
		SCmd.transfersize = 0;
		SCmd.underflow = 0;
		SCmd.index = NR_SCSI_DEVICES;

		scsi_do_cmd (&SCmd,
			     (void *)  scsi_cmd, (void *) 
			     scsi_result, 256,  scan_scsis_done, 
			     SCSI_TIMEOUT + 400, 5);
		
		while (SCmd.request.dev != 0xfffe);
#if defined(DEBUG) || defined(DEBUG_INIT)
		printk("scsi: scan SCSIS id %d lun %d\n", dev, lun);
		printk("scsi: return code %08x\n", SCmd.result);
#endif


		if(SCmd.result) {
		  if ((driver_byte(SCmd.result)  & DRIVER_SENSE) &&
		      ((SCmd.sense_buffer[0] & 0x70) >> 4) == 7) {
		    if (SCmd.sense_buffer[2] &0xe0)
		      continue; /* No devices here... */
		    if(((SCmd.sense_buffer[2] & 0xf) != NOT_READY) &&
		       ((SCmd.sense_buffer[2] & 0xf) != UNIT_ATTENTION))
		      continue;
		  }
		  else
		    break;
		};

#if defined (DEBUG) || defined(DEBUG_INIT)
		printk("scsi: performing INQUIRY\n");
#endif

		/*
		 * Build an INQUIRY command block.  
		 */
		
		scsi_cmd[0] = INQUIRY;
		scsi_cmd[1] = (lun << 5) & 0xe0;
		scsi_cmd[2] = 0;
		scsi_cmd[3] = 0;
		scsi_cmd[4] = 255;
		scsi_cmd[5] = 0;
		
		SCmd.request.dev = 0xffff; /* Mark not busy */
		
		scsi_do_cmd (&SCmd,
			     (void *)  scsi_cmd, (void *) 
			     scsi_result, 256,  scan_scsis_done, 
			     SCSI_TIMEOUT, 3);
		
		while (SCmd.request.dev != 0xfffe);
		
		the_result = SCmd.result;
		
#if defined(DEBUG) || defined(DEBUG_INIT)
		if (!the_result)
			printk("scsi: INQUIRY successful\n");
		else
			printk("scsi: INQUIRY failed with code %08x\n");
#endif

		if(the_result) break; 

		/* skip other luns on this device */
		
		if (!the_result)
		  {
		    scsi_devices[NR_SCSI_DEVICES].
		      removable = (0x80 & 
				   scsi_result[1]) >> 7;
		    scsi_devices[NR_SCSI_DEVICES].lockable =
		      scsi_devices[NR_SCSI_DEVICES].removable;
		    scsi_devices[NR_SCSI_DEVICES].
		      changed = 0;
		    scsi_devices[NR_SCSI_DEVICES].
		      access_count = 0;
		    scsi_devices[NR_SCSI_DEVICES].
		      busy = 0;
/* 
 *	Currently, all sequential devices are assumed to be tapes,
 *	all random devices disk, with the appropriate read only 
 *	flags set for ROM / WORM treated as RO.
 */ 

		    switch (type = scsi_result[0])
		      {
		      case TYPE_TAPE :
		      case TYPE_DISK :
		      case TYPE_MOD :
			scsi_devices[NR_SCSI_DEVICES].writeable = 1;
			break;
		      case TYPE_WORM :
		      case TYPE_ROM :
			scsi_devices[NR_SCSI_DEVICES].writeable = 0;
			break;
			default :
#if 0
#ifdef DEBUG
			printk("scsi: unknown type %d\n", type);
			print_inquiry(scsi_result);
#endif
#endif
			  type = -1;
		      }

		    scsi_devices[NR_SCSI_DEVICES].random = 
		      (type == TYPE_TAPE) ? 0 : 1;
		    scsi_devices[NR_SCSI_DEVICES].type = type;

		    if (type != -1)
		      {
			print_inquiry(scsi_result);
			switch(type){
			case TYPE_TAPE:
			  printk("Detected scsi tape st%d at scsi%d, id %d, lun %d\n", MAX_ST,
				 shpnt->host_no , dev, lun); 
			  if(NR_ST != -1) ++MAX_ST;
			  break;
			case TYPE_ROM:
			  printk("Detected scsi CD-ROM sr%d at scsi%d, id %d, lun %d\n", MAX_SR,
				 shpnt->host_no , dev, lun); 
			  if(NR_SR != -1) ++MAX_SR;
			  break;
			case TYPE_DISK:
			case TYPE_MOD:
			  printk("Detected scsi disk sd%c at scsi%d, id %d, lun %d\n", 'a'+MAX_SD,
				 shpnt->host_no , dev, lun); 
			  if(NR_SD != -1) ++MAX_SD;
			  break;
			default:
			  break;
			};

			if(NR_SG != -1) ++MAX_SG;

			scsi_devices[NR_SCSI_DEVICES].scsi_level =
			  scsi_result[2] & 0x07;
			if (scsi_devices[NR_SCSI_DEVICES].scsi_level >= 2 ||
			    (scsi_devices[NR_SCSI_DEVICES].scsi_level == 1 &&
			     (scsi_result[3] & 0x0f) == 1))
			  scsi_devices[NR_SCSI_DEVICES].scsi_level++;
/* 
 * Set the tagged_queue flag for SCSI-II devices that purport to support
 * tagged queuing in the INQUIRY data.
 */

			scsi_devices[NR_SCSI_DEVICES].tagged_queue = 0;

			if ((scsi_devices[NR_SCSI_DEVICES].scsi_level >= SCSI_2) &&
			    (scsi_result[7] & 2)) {
			    scsi_devices[NR_SCSI_DEVICES].tagged_supported = 1;
			    scsi_devices[NR_SCSI_DEVICES].current_tag = 0;
			}

/*
 * Accomodate drivers that want to sleep when they should be in a polling
 * loop.
 */

			scsi_devices[NR_SCSI_DEVICES].disconnect = 0;

/*
 * Some revisions of the Texel CD ROM drives have handshaking
 * problems when used with the Seagate controllers.  Before we
 * know what type of device we're talking to, we assume it's 
 * borken and then change it here if it turns out that it isn't
 * a TEXEL drive.
 */

			if(strncmp("TEXEL", (char *) &scsi_result[8], 5) != 0 ||
			  strncmp("CD-ROM", (char *) &scsi_result[16], 6) != 0 
/* 
 * XXX 1.06 has problems, some one should figure out the others too so
 * ALL TEXEL drives don't suffer in performance, especially when I finish
 * integrating my seagate patches which do multiple I_T_L nexuses.
 */

#ifdef notyet
			   || (strncmp("1.06", (char *) &scsi_result[[, 4) != 0)
#endif
			   )
			   scsi_devices[NR_SCSI_DEVICES].borken = 0;


			/* These devices need this "key" to unlock the device
			   so we can use it */
			if(memcmp("INSITE", &scsi_result[8], 6) == 0 &&
			   (memcmp("Floptical   F*8I", &scsi_result[16], 16) == 0
			    || memcmp("I325VM", &scsi_result[16], 6) == 0)) {
			  printk("Unlocked floptical drive.\n");
			  scsi_devices[NR_SCSI_DEVICES].lockable = 0;
			  scsi_cmd[0] = MODE_SENSE;
			  scsi_cmd[1] = (lun << 5) & 0xe0;
			  scsi_cmd[2] = 0x2e;
			  scsi_cmd[3] = 0;
			  scsi_cmd[4] = 0x2a;
			  scsi_cmd[5] = 0;
		
			  SCmd.request.dev = 0xffff; /* Mark not busy */
			  
			  scsi_do_cmd (&SCmd,
				       (void *)  scsi_cmd, (void *) 
				       scsi_result, 0x2a,  scan_scsis_done, 
				       SCSI_TIMEOUT, 3);
		
			  while (SCmd.request.dev != 0xfffe);
			};

			++NR_SCSI_DEVICES;
			/* Some scsi devices cannot be polled for lun != 0
			   due to firmware bugs */
			if(blacklisted(scsi_result)) break;
			/* Old drives like the MAXTOR XT-3280 say vers=0 */
			if ((scsi_result[2] & 0x07) == 0)
			    break;
			/* Some scsi-1 peripherals do not handle lun != 0.
			   I am assuming that scsi-2 peripherals do better */
			if((scsi_result[2] & 0x07) == 1 && 
			   (scsi_result[3] & 0x0f) == 0) break;
			}
		  }       /* if result == DID_OK ends */
	      }       /* for lun ends */
	shpnt->host_queue = NULL;  /* No longer needed here */
      }      	/* if present */  
  
  printk("scsi : detected ");
  if(NR_SD != -1)
    printk("%d SCSI disk%s ", MAX_SD, (MAX_SD != 1) ? "s" : "");
	 
  if(NR_ST != -1)
    printk("%d tape%s ", MAX_ST, (MAX_ST != 1) ? "s" : "");

  if(NR_SR != -1)
    printk("%d CD-ROM drive%s ", MAX_SR, (MAX_SR != 1) ? "s" : "");

  printk("total.\n");
  in_scan = 0;
}       /* scan_scsis  ends */

/*
 *	Flag bits for the internal_timeout array 
 */

#define NORMAL_TIMEOUT 0
#define IN_ABORT 1
#define IN_RESET 2
/*
	This is our time out function, called when the timer expires for a 
	given host adapter.  It will attempt to abort the currently executing 
	command, that failing perform a kernel panic.
*/ 

static void scsi_times_out (Scsi_Cmnd * SCpnt)
	{
	
 	switch (SCpnt->internal_timeout & (IN_ABORT | IN_RESET))
		{
		case NORMAL_TIMEOUT:
			if (!in_scan)
			      printk("SCSI host %d timed out - aborting command\n",
				SCpnt->host->host_no);
			
			if (!scsi_abort	(SCpnt, DID_TIME_OUT))
				return;				
		case IN_ABORT:
			printk("SCSI host %d abort() timed out - reseting\n",
				SCpnt->host->host_no);
			if (!scsi_reset (SCpnt)) 
				return;
		case IN_RESET:
		case (IN_ABORT | IN_RESET):
			panic("Unable to reset scsi host %d\n",SCpnt->host->host_no);
		default:
			INTERNAL_ERROR;
		}
					
	}


/* This function takes a quick look at a request, and decides if it
can be queued now, or if there would be a stall while waiting for
something else to finish.  This routine assumes that interrupts are
turned off when entering the routine.  It is the responsibility
of the calling code to ensure that this is the case. */

Scsi_Cmnd * request_queueable (struct request * req, int index)
{
  Scsi_Cmnd * SCpnt = NULL;
  int tablesize;
  struct buffer_head * bh;

  if ((index < 0) ||  (index > NR_SCSI_DEVICES))
    panic ("Index number in allocate_device() is out of range.\n");
  
  if (req && req->dev <= 0)
    panic("Invalid device in allocate_device");
  
  SCpnt =  scsi_devices[index].host->host_queue;
    while(SCpnt){
      if(SCpnt->target == scsi_devices[index].id &&
	 SCpnt->lun == scsi_devices[index].lun)
	if(SCpnt->request.dev < 0) break;
      SCpnt = SCpnt->next;
    };

  if (!SCpnt) return NULL;

  if (scsi_devices[index].host->hostt->can_queue
      && scsi_devices[index].host->host_busy >= scsi_devices[index].host->hostt->can_queue) return NULL;

  if (req) {
    memcpy(&SCpnt->request, req, sizeof(struct request));
    tablesize = scsi_devices[index].host->sg_tablesize;
    bh = req->bh;
    if(!tablesize) bh = NULL;
    /* Take a quick look through the table to see how big it is.  We already
       have our copy of req, so we can mess with that if we want to.  */
    while(req->nr_sectors && bh){
	    tablesize--;
	    req->nr_sectors -= bh->b_size >> 9;
	    req->sector += bh->b_size >> 9;
	    if(!tablesize) break;
	    bh = bh->b_reqnext;
    };
    if(req->nr_sectors && bh && bh->b_reqnext){  /* Any leftovers? */
      SCpnt->request.bhtail = bh;
      req->bh = bh->b_reqnext; /* Divide request */
      bh->b_reqnext = NULL;
      bh = req->bh;