drivers/scsi/sg.c

/* */
This source file includes following definitions.
sg_ioctl
sg_open
sg_close
sg_malloc
sg_free
sg_read
sg_command_done
sg_write
sg_select
sg_detect
sg_init
sg_attach
sg_detach
init_module
cleanup_module
   1 /*
   2  *  History:
   3  *  Started: Aug 9 by Lawrence Foard (entropy@world.std.com), 
   4  *           to allow user process control of SCSI devices.
   5  *  Development Sponsored by Killy Corp. NY NY
   6  *   
   7  *  Borrows code from st driver.
   8  */
   9 #include <linux/module.h>
  10 
  11 #include <linux/fs.h>
  12 #include <linux/kernel.h>
  13 #include <linux/sched.h>
  14 #include <linux/string.h>
  15 #include <linux/mm.h>
  16 #include <linux/errno.h>
  17 #include <linux/mtio.h>
  18 #include <linux/ioctl.h>
  19 #include <linux/fcntl.h>
  20 #include <asm/io.h>
  21 #include <asm/segment.h>
  22 #include <asm/system.h>
  23 
  24 #include <linux/blk.h>
  25 #include "scsi.h"
  26 #include "hosts.h"
  27 #include "scsi_ioctl.h"
  28 #include "sg.h"
  29 
  30 static int sg_init(void);
  31 static int sg_attach(Scsi_Device *);
  32 static int sg_detect(Scsi_Device *);
  33 static void sg_detach(Scsi_Device *);
  34 
  35 
  36 struct Scsi_Device_Template sg_template = {NULL, NULL, "sg", NULL, 0xff, 
  37                                                SCSI_GENERIC_MAJOR, 0, 0, 0, 0,
  38                                                sg_detect, sg_init,
  39                                                NULL, sg_attach, sg_detach};
  40 
  41 #ifdef SG_BIG_BUFF
  42 static char *big_buff = NULL;
  43 static struct wait_queue *big_wait;   /* wait for buffer available */
  44 static int big_inuse=0;
  45 #endif
  46 
  47 struct scsi_generic
  48 {
  49     Scsi_Device *device;
  50     int users;   /* how many people have it open? */
  51     struct wait_queue *generic_wait; /* wait for device to be available */
  52     struct wait_queue *read_wait;    /* wait for response */
  53     struct wait_queue *write_wait;   /* wait for free buffer */
  54     int timeout; /* current default value for device */
  55     int buff_len; /* length of current buffer */
  56     char *buff;   /* the buffer */
  57     struct sg_header header; /* header of pending command */
  58     char exclude; /* opened for exclusive access */
  59     char pending;  /* don't accept writes now */
  60     char complete; /* command complete allow a read */
  61 };
  62 
  63 static struct scsi_generic *scsi_generics=NULL;
  64 static void sg_free(char *buff,int size);
  65 
  66 static int sg_ioctl(struct inode * inode,struct file * file,
     /*  */
  67                     unsigned int cmd_in, unsigned long arg)
  68 {
  69     int result;
  70     int dev = MINOR(inode->i_rdev);
  71     if ((dev<0) || (dev>=sg_template.dev_max))
  72         return -ENXIO;
  73     switch(cmd_in)
  74     {
  75     case SG_SET_TIMEOUT:
  76         result = verify_area(VERIFY_READ, (const void *)arg, sizeof(long));
  77         if (result) return result;
  78 
  79         scsi_generics[dev].timeout=get_user((int *) arg);
  80         return 0;
  81     case SG_GET_TIMEOUT:
  82         return scsi_generics[dev].timeout;
  83     default:
  84         return scsi_ioctl(scsi_generics[dev].device, cmd_in, (void *) arg);
  85     }
  86 }
  87 
  88 static int sg_open(struct inode * inode, struct file * filp)
     /*  */
  89 {
  90     int dev=MINOR(inode->i_rdev);
  91     int flags=filp->f_flags;
  92     if (dev>=sg_template.dev_max || !scsi_generics[dev].device)
  93         return -ENXIO;
  94     if (O_RDWR!=(flags & O_ACCMODE))
  95         return -EACCES;
  96 
  97   /*
  98    * If we want exclusive access, then wait until the device is not
  99    * busy, and then set the flag to prevent anyone else from using it.
 100    */
 101     if (flags & O_EXCL)
 102     {
 103         while(scsi_generics[dev].users)
 104         {
 105             if (flags & O_NONBLOCK)
 106                 return -EBUSY;
 107             interruptible_sleep_on(&scsi_generics[dev].generic_wait);
 108             if (current->signal & ~current->blocked)
 109                 return -ERESTARTSYS;
 110         }
 111         scsi_generics[dev].exclude=1;
 112     }
 113     else
 114         /*
 115          * Wait until nobody has an exclusive open on
 116          * this device.
 117          */
 118         while(scsi_generics[dev].exclude)
 119         {
 120             if (flags & O_NONBLOCK)
 121                 return -EBUSY;
 122             interruptible_sleep_on(&scsi_generics[dev].generic_wait);
 123             if (current->signal & ~current->blocked)
 124                 return -ERESTARTSYS;
 125         }
 126 
 127     /*
 128      * OK, we should have grabbed the device.  Mark the thing so
 129      * that other processes know that we have it, and initialize the
 130      * state variables to known values.
 131      */
 132     if (!scsi_generics[dev].users 
 133         && scsi_generics[dev].pending
 134         && scsi_generics[dev].complete)
 135     {
 136         if (scsi_generics[dev].buff != NULL)
 137             sg_free(scsi_generics[dev].buff,scsi_generics[dev].buff_len);
 138         scsi_generics[dev].buff=NULL;
 139         scsi_generics[dev].pending=0;
 140     }
 141     if (!scsi_generics[dev].users)
 142         scsi_generics[dev].timeout=SG_DEFAULT_TIMEOUT;
 143     if (scsi_generics[dev].device->host->hostt->usage_count)
 144         (*scsi_generics[dev].device->host->hostt->usage_count)++;
 145     if(sg_template.usage_count) (*sg_template.usage_count)++;
 146     scsi_generics[dev].users++;
 147     return 0;
 148 }
 149 
 150 static void sg_close(struct inode * inode, struct file * filp)
     /*  */
 151 {
 152     int dev=MINOR(inode->i_rdev);
 153     scsi_generics[dev].users--;
 154     if (scsi_generics[dev].device->host->hostt->usage_count)
 155         (*scsi_generics[dev].device->host->hostt->usage_count)--;
 156     if(sg_template.usage_count) (*sg_template.usage_count)--;
 157     scsi_generics[dev].exclude=0;
 158     wake_up(&scsi_generics[dev].generic_wait);
 159 }
 160 
 161 static char *sg_malloc(int size)
     /*  */
 162 {
 163     if (size<=4096)
 164         return (char *) scsi_malloc(size);
 165 #ifdef SG_BIG_BUFF
 166     if (size<=SG_BIG_BUFF)
 167     {
 168         while(big_inuse)
 169         {
 170             interruptible_sleep_on(&big_wait);
 171             if (current->signal & ~current->blocked)
 172                 return NULL;
 173         }
 174         big_inuse=1;
 175         return big_buff;
 176     }
 177 #endif   
 178     return NULL;
 179 }
 180 
 181 static void sg_free(char *buff,int size) 
     /*  */
 182 {
 183 #ifdef SG_BIG_BUFF
 184     if (buff==big_buff)
 185     {
 186         big_inuse=0;
 187         wake_up(&big_wait);
 188         return;
 189     }
 190 #endif
 191     scsi_free(buff,size);
 192 }
 193 
 194 /*
 195  * Read back the results of a previous command.  We use the pending and
 196  * complete semaphores to tell us whether the buffer is available for us
 197  * and whether the command is actually done.
 198  */
 199 static int sg_read(struct inode *inode,struct file *filp,char *buf,int count)
     /*  */
 200 {
 201     int dev=MINOR(inode->i_rdev);
 202     int i;
 203     unsigned long flags;
 204     struct scsi_generic *device=&scsi_generics[dev];
 205     if ((i=verify_area(VERIFY_WRITE,buf,count)))
 206         return i;
 207 
 208     /*
 209      * Wait until the command is actually done.
 210      */
 211     save_flags(flags);
 212     cli();
 213     while(!device->pending || !device->complete)
 214     {
 215         if (filp->f_flags & O_NONBLOCK)
 216         {
 217             restore_flags(flags);
 218             return -EWOULDBLOCK;
 219         }
 220         interruptible_sleep_on(&device->read_wait);
 221         if (current->signal & ~current->blocked)
 222         {
 223             restore_flags(flags);
 224             return -ERESTARTSYS;
 225         }
 226     }
 227     restore_flags(flags);
 228 
 229     /*
 230      * Now copy the result back to the user buffer.
 231      */
 232     device->header.pack_len=device->header.reply_len;
 233     device->header.result=0;
 234     if (count>=sizeof(struct sg_header))
 235     {
 236         memcpy_tofs(buf,&device->header,sizeof(struct sg_header));
 237         buf+=sizeof(struct sg_header);
 238         if (count>device->header.pack_len)
 239             count=device->header.pack_len;
 240         if (count > sizeof(struct sg_header)) {
 241             memcpy_tofs(buf,device->buff,count-sizeof(struct sg_header));
 242         }
 243     }
 244     else
 245         count=0;
 246     
 247     /*
 248      * Clean up, and release the device so that we can send another
 249      * command.
 250      */
 251     sg_free(device->buff,device->buff_len);
 252     device->buff = NULL;
 253     device->pending=0;
 254     wake_up(&device->write_wait);
 255     return count;
 256 }
 257 
 258 /*
 259  * This function is called by the interrupt handler when we
 260  * actually have a command that is complete.  Change the
 261  * flags to indicate that we have a result.
 262  */
 263 static void sg_command_done(Scsi_Cmnd * SCpnt)
     /*  */
 264 {
 265     int dev = MINOR(SCpnt->request.rq_dev);
 266     struct scsi_generic *device = &scsi_generics[dev];
 267     if (!device->pending)
 268     {
 269         printk("unexpected done for sg %d\n",dev);
 270         SCpnt->request.rq_status = RQ_INACTIVE;
 271         return;
 272     }
 273 
 274     /*
 275      * See if the command completed normally, or whether something went
 276      * wrong.
 277      */
 278     memcpy(device->header.sense_buffer, SCpnt->sense_buffer, sizeof(SCpnt->sense_buffer));
 279     if (SCpnt->sense_buffer[0])
 280     {
 281         device->header.result=EIO;
 282     }
 283     else
 284         device->header.result=SCpnt->result;
 285 
 286     /*
 287      * Now wake up the process that is waiting for the
 288      * result.
 289      */
 290     device->complete=1;
 291     SCpnt->request.rq_status = RQ_INACTIVE;
 292     wake_up(&scsi_generics[dev].read_wait);
 293 }
 294 
 295 #define SG_SEND 0
 296 #define SG_REC  1
 297 
 298 static int sg_write(struct inode *inode,struct file *filp,const char *buf,int count)
     /*  */
 299 {
 300     int                   bsize,size,amt,i;
 301     unsigned char         cmnd[MAX_COMMAND_SIZE];
 302     kdev_t                devt = inode->i_rdev;
 303     int                   dev = MINOR(devt);
 304     struct scsi_generic   * device=&scsi_generics[dev];
 305     int                   direction;
 306     unsigned char         opcode;
 307     Scsi_Cmnd           * SCpnt;
 308     
 309     if ((i=verify_area(VERIFY_READ,buf,count)))
 310         return i;
 311     /*
 312      * The minimum scsi command length is 6 bytes.  If we get anything
 313      * less than this, it is clearly bogus.  
 314      */
 315     if (count<(sizeof(struct sg_header) + 6))
 316         return -EIO;
 317 
 318     /*
 319      * If we still have a result pending from a previous command,
 320      * wait until the result has been read by the user before sending
 321      * another command.
 322      */
 323     while(device->pending)
 324     {
 325         if (filp->f_flags & O_NONBLOCK)
 326             return -EWOULDBLOCK;
 327 #ifdef DEBUG
 328         printk("sg_write: sleeping on pending request\n");
 329 #endif     
 330         interruptible_sleep_on(&device->write_wait);
 331         if (current->signal & ~current->blocked)
 332             return -ERESTARTSYS;
 333     }
 334 
 335     /*
 336      * Mark the device flags for the new state.
 337      */
 338     device->pending=1;
 339     device->complete=0;
 340     memcpy_fromfs(&device->header,buf,sizeof(struct sg_header));
 341 
 342     /*
 343      * fix input size, and see if we are sending data.
 344      */
 345     device->header.pack_len=count;
 346     buf+=sizeof(struct sg_header);
 347     if( device->header.pack_len > device->header.reply_len )
 348     {
 349         bsize = device->header.pack_len;
 350         direction = SG_SEND;
 351     } else {
 352         bsize = device->header.reply_len;
 353         direction = SG_REC;
 354     }
 355     
 356     /*
 357      * Don't include the command header itself in the size.
 358      */
 359     bsize-=sizeof(struct sg_header);
 360 
 361     /*
 362      * Allocate a buffer that is large enough to hold the data
 363      * that has been requested.  Round up to an even number of sectors,
 364      * since scsi_malloc allocates in chunks of 512 bytes.
 365      */
 366     amt=bsize;
 367     if (!bsize)
 368         bsize++;
 369     bsize=(bsize+511) & ~511;
 370 
 371     /*
 372      * If we cannot allocate the buffer, report an error.
 373      */
 374     if ((bsize<0) || !(device->buff=sg_malloc(device->buff_len=bsize)))
 375     {
 376         device->pending=0;
 377         wake_up(&device->write_wait);
 378         return -ENOMEM;
 379     }
 380 
 381 #ifdef DEBUG
 382     printk("allocating device\n");
 383 #endif
 384 
 385     /*
 386      * Grab a device pointer for the device we want to talk to.  If we
 387      * don't want to block, just return with the appropriate message.
 388      */
 389     if (!(SCpnt=allocate_device(NULL,device->device, !(filp->f_flags & O_NONBLOCK))))
 390     {
 391         device->pending=0;
 392         wake_up(&device->write_wait);
 393         sg_free(device->buff,device->buff_len);
 394         device->buff = NULL;
 395         return -EWOULDBLOCK;
 396     } 
 397 #ifdef DEBUG
 398     printk("device allocated\n");
 399 #endif    
 400 
 401     /*
 402      * Now we need to grab the command itself from the user's buffer.
 403      */
 404     SCpnt->request.rq_dev = devt;
 405     SCpnt->request.rq_status = RQ_ACTIVE;
 406     SCpnt->sense_buffer[0]=0;
 407     opcode = get_user(buf);
 408     size=COMMAND_SIZE(opcode);
 409     if (opcode >= 0xc0 && device->header.twelve_byte) size = 12;
 410     SCpnt->cmd_len = size;
 411 
 412     /*
 413      * If we are writing data, subtract off the size
 414      * of the command itself, to get the amount of actual data
 415      * that we need to send to the device.
 416      */
 417     if( direction == SG_SEND )
 418         amt -= size;
 419     
 420     /*
 421      * Verify that the user has actually passed enough bytes for this command.
 422      */
 423     if( count < (sizeof(struct sg_header) + size) )
 424     {
 425         device->pending=0;
 426         wake_up( &device->write_wait );
 427         sg_free( device->buff, device->buff_len );
 428         device->buff = NULL;
 429         return -EIO;
 430     }
 431     
 432     /*
 433      * Now copy the SCSI command from the user's address space.
 434      */
 435     memcpy_fromfs(cmnd,buf,size);
 436     buf+=size;
 437 
 438     /*
 439      * If we are writing data, copy the data we are writing.  The pack_len
 440      * field also includes the length of the header and the command,
 441      * so we need to subtract these off.
 442      */
 443     if( direction == SG_SEND )  memcpy_fromfs(device->buff,buf, amt);
 444     
 445     /*
 446      * Set the LUN field in the command structure.
 447      */
 448     cmnd[1]= (cmnd[1] & 0x1f) | (device->device->lun<<5);
 449 
 450 #ifdef DEBUG
 451     printk("do cmd\n");
 452 #endif
 453 
 454     /*
 455      * Now pass the actual command down to the low-level driver.  We
 456      * do not do any more here - when the interrupt arrives, we will
 457      * then do the post-processing.
 458      */
 459     scsi_do_cmd (SCpnt,(void *) cmnd,
 460                  (void *) device->buff,amt,
 461                  sg_command_done,device->timeout,SG_DEFAULT_RETRIES);
 462 
 463 #ifdef DEBUG
 464     printk("done cmd\n");
 465 #endif               
 466 
 467     return count;
 468 }
 469 
 470 static int sg_select(struct inode *inode, struct file *file, int sel_type, select_table * wait)
     /*  */
 471 {
 472     int dev=MINOR(inode->i_rdev);
 473     int r = 0;
 474     struct scsi_generic *device=&scsi_generics[dev];
 475 
 476     if (sel_type == SEL_IN) {
 477         if(device->pending && device->complete)
 478         {
 479             r = 1;
 480         } else {
 481             select_wait(&scsi_generics[dev].read_wait, wait);
 482         }
 483     }
 484     if (sel_type == SEL_OUT) {
 485         if(!device->pending){
 486             r = 1;
 487         }
 488         else
 489         {
 490             select_wait(&scsi_generics[dev].write_wait, wait);
 491         }
 492     }
 493 
 494     return(r);
 495 }
 496 
 497 static struct file_operations sg_fops = {
 498     NULL,            /* lseek */
 499     sg_read,         /* read */
 500     sg_write,        /* write */
 501     NULL,            /* readdir */
 502     sg_select,       /* select */
 503     sg_ioctl,        /* ioctl */
 504     NULL,            /* mmap */
 505     sg_open,         /* open */
 506     sg_close,        /* release */
 507     NULL             /* fsync */
 508 };
 509 
 510 
 511 static int sg_detect(Scsi_Device * SDp){
     /*  */
 512     ++sg_template.dev_noticed;
 513     return 1;
 514 }
 515 
 516 /* Driver initialization */
 517 static int sg_init()
     /*  */
 518 {
 519     static int sg_registered = 0;
 520     
 521     if (sg_template.dev_noticed == 0) return 0;
 522     
 523     if(!sg_registered) {
 524         if (register_chrdev(SCSI_GENERIC_MAJOR,"sg",&sg_fops)) 
 525         {
 526             printk("Unable to get major %d for generic SCSI device\n",
 527                    SCSI_GENERIC_MAJOR);
 528             return 1;
 529         }
 530         sg_registered++;
 531     }
 532     
 533     /* If we have already been through here, return */
 534     if(scsi_generics) return 0;
 535     
 536 #ifdef DEBUG
 537     printk("sg: Init generic device.\n");
 538 #endif
 539     
 540 #ifdef SG_BIG_BUFF
 541     big_buff= (char *) scsi_init_malloc(SG_BIG_BUFF, GFP_ATOMIC | GFP_DMA);
 542 #endif
 543     
 544     scsi_generics = (struct scsi_generic *) 
 545         scsi_init_malloc((sg_template.dev_noticed + SG_EXTRA_DEVS) 
 546                          * sizeof(struct scsi_generic), GFP_ATOMIC);
 547     memset(scsi_generics, 0, (sg_template.dev_noticed + SG_EXTRA_DEVS)
 548            * sizeof(struct scsi_generic));
 549     
 550     sg_template.dev_max = sg_template.dev_noticed + SG_EXTRA_DEVS;
 551     return 0;
 552 }
 553 
 554 static int sg_attach(Scsi_Device * SDp)
     /*  */
 555 {
 556     struct scsi_generic * gpnt;
 557     int i;
 558     
 559     if(sg_template.nr_dev >= sg_template.dev_max) 
 560     {
 561         SDp->attached--;
 562         return 1;
 563     }
 564     
 565     for(gpnt = scsi_generics, i=0; i<sg_template.dev_max; i++, gpnt++) 
 566         if(!gpnt->device) break;
 567     
 568     if(i >= sg_template.dev_max) panic ("scsi_devices corrupt (sg)");
 569     
 570     scsi_generics[i].device=SDp;
 571     scsi_generics[i].users=0;
 572     scsi_generics[i].generic_wait=NULL;
 573     scsi_generics[i].read_wait=NULL;
 574     scsi_generics[i].write_wait=NULL;
 575     scsi_generics[i].buff=NULL;
 576     scsi_generics[i].exclude=0;
 577     scsi_generics[i].pending=0;
 578     scsi_generics[i].timeout=SG_DEFAULT_TIMEOUT;
 579     sg_template.nr_dev++;
 580     return 0;
 581 };
 582 
 583 
 584 
 585 static void sg_detach(Scsi_Device * SDp)
     /*  */
 586 {
 587     struct scsi_generic * gpnt;
 588     int i;
 589     
 590     for(gpnt = scsi_generics, i=0; i<sg_template.dev_max; i++, gpnt++) 
 591         if(gpnt->device == SDp) {
 592             gpnt->device = NULL;
 593             SDp->attached--;
 594             sg_template.nr_dev--;
 595             return;
 596         }
 597     return;
 598 }
 599 
 600 #ifdef MODULE
 601 
 602 int init_module(void) {
     /*  */
 603     sg_template.usage_count = &mod_use_count_;
 604     return scsi_register_module(MODULE_SCSI_DEV, &sg_template);
 605 }
 606 
 607 void cleanup_module( void) 
     /*  */
 608 {
 609     scsi_unregister_module(MODULE_SCSI_DEV, &sg_template);
 610     unregister_chrdev(SCSI_GENERIC_MAJOR, "sg");
 611     
 612     if(scsi_generics != NULL) {
 613         scsi_init_free((char *) scsi_generics,
 614                        (sg_template.dev_noticed + SG_EXTRA_DEVS) 
 615                        * sizeof(struct scsi_generic));
 616     }
 617     sg_template.dev_max = 0;
 618 #ifdef SG_BIG_BUFF
 619     if(big_buff != NULL)
 620         scsi_init_free(big_buff, SG_BIG_BUFF);
 621 #endif
 622 }
 623 #endif /* MODULE */
 624 
 625 /*
 626  * Overrides for Emacs so that we almost follow Linus's tabbing style.
 627  * Emacs will notice this stuff at the end of the file and automatically
 628  * adjust the settings for this buffer only.  This must remain at the end
 629  * of the file.
 630  * ---------------------------------------------------------------------------
 631  * Local variables:
 632  * c-indent-level: 4
 633  * c-brace-imaginary-offset: 0
 634  * c-brace-offset: -4
 635  * c-argdecl-indent: 4
 636  * c-label-offset: -4
 637  * c-continued-statement-offset: 4
 638  * c-continued-brace-offset: 0
 639  * indent-tabs-mode: nil
 640  * tab-width: 8
 641  * End:
 642  */
/* */
root/drivers/scsi/sg.c

DEFINITIONS
