drivers/ide/legacy/hd.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *
   4  * This is the low-level hd interrupt support. It traverses the
   5  * request-list, using interrupts to jump between functions. As
   6  * all the functions are called within interrupts, we may not
   7  * sleep. Special care is recommended.
   8  *
   9  *  modified by Drew Eckhardt to check nr of hd's from the CMOS.
  10  *
  11  *  Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug
  12  *  in the early extended-partition checks and added DM partitions
  13  *
  14  *  IRQ-unmask, drive-id, multiple-mode, support for ">16 heads",
  15  *  and general streamlining by Mark Lord.
  16  *
  17  *  Removed 99% of above. Use Mark's ide driver for those options.
  18  *  This is now a lightweight ST-506 driver. (Paul Gortmaker)
  19  *
  20  *  Modified 1995 Russell King for ARM processor.
  21  *
  22  *  Bugfix: max_sectors must be <= 255 or the wheels tend to come
  23  *  off in a hurry once you queue things up - Paul G. 02/2001
  24  */
  25
  26 /* Uncomment the following if you want verbose error reports. */
  27 /* #define VERBOSE_ERRORS */
  28
  29 #include <linux/blkdev.h>
  30 #include <linux/errno.h>
  31 #include <linux/signal.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/timer.h>
  34 #include <linux/fs.h>
  35 #include <linux/kernel.h>
  36 #include <linux/genhd.h>
  37 #include <linux/slab.h>
  38 #include <linux/string.h>
  39 #include <linux/ioport.h>
  40 #include <linux/mc146818rtc.h> /* CMOS defines */
  41 #include <linux/init.h>
  42 #include <linux/blkpg.h>
  43 #include <linux/hdreg.h>
  44
  45 #define REALLY_SLOW_IO
  46 #include <asm/system.h>
  47 #include <asm/io.h>
  48 #include <asm/uaccess.h>
  49
  50 #ifdef __arm__
  51 #undef  HD_IRQ
  52 #endif
  53 #include <asm/irq.h>
  54 #ifdef __arm__
  55 #define HD_IRQ IRQ_HARDDISK
  56 #endif
  57
  58 /* Hd controller regster ports */
  59
  60 #define HD_DATA         0x1f0           /* _CTL when writing */
  61 #define HD_ERROR        0x1f1           /* see err-bits */
  62 #define HD_NSECTOR      0x1f2           /* nr of sectors to read/write */
  63 #define HD_SECTOR       0x1f3           /* starting sector */
  64 #define HD_LCYL         0x1f4           /* starting cylinder */
  65 #define HD_HCYL         0x1f5           /* high byte of starting cyl */
  66 #define HD_CURRENT      0x1f6           /* 101dhhhh , d=drive, hhhh=head */
  67 #define HD_STATUS       0x1f7           /* see status-bits */
  68 #define HD_FEATURE      HD_ERROR        /* same io address, read=error, write=feature */
  69 #define HD_PRECOMP      HD_FEATURE      /* obsolete use of this port - predates IDE */
  70 #define HD_COMMAND      HD_STATUS       /* same io address, read=status, write=cmd */
  71
  72 #define HD_CMD          0x3f6           /* used for resets */
  73 #define HD_ALTSTATUS    0x3f6           /* same as HD_STATUS but doesn't clear irq */
  74
  75 /* Bits of HD_STATUS */
  76 #define ERR_STAT                0x01
  77 #define INDEX_STAT              0x02
  78 #define ECC_STAT                0x04    /* Corrected error */
  79 #define DRQ_STAT                0x08
  80 #define SEEK_STAT               0x10
  81 #define SERVICE_STAT            SEEK_STAT
  82 #define WRERR_STAT              0x20
  83 #define READY_STAT              0x40
  84 #define BUSY_STAT               0x80
  85
  86 /* Bits for HD_ERROR */
  87 #define MARK_ERR                0x01    /* Bad address mark */
  88 #define TRK0_ERR                0x02    /* couldn't find track 0 */
  89 #define ABRT_ERR                0x04    /* Command aborted */
  90 #define MCR_ERR                 0x08    /* media change request */
  91 #define ID_ERR                  0x10    /* ID field not found */
  92 #define MC_ERR                  0x20    /* media changed */
  93 #define ECC_ERR                 0x40    /* Uncorrectable ECC error */
  94 #define BBD_ERR                 0x80    /* pre-EIDE meaning:  block marked bad */
  95 #define ICRC_ERR                0x80    /* new meaning:  CRC error during transfer */
  96
  97 static DEFINE_SPINLOCK(hd_lock);
  98 static struct request_queue *hd_queue;
  99
 100 #define MAJOR_NR HD_MAJOR
 101 #define QUEUE (hd_queue)
 102 #define CURRENT elv_next_request(hd_queue)
 103
 104 #define TIMEOUT_VALUE   (6*HZ)
 105 #define HD_DELAY        0
 106
 107 #define MAX_ERRORS     16       /* Max read/write errors/sector */
 108 #define RESET_FREQ      8       /* Reset controller every 8th retry */
 109 #define RECAL_FREQ      4       /* Recalibrate every 4th retry */
 110 #define MAX_HD          2
 111
 112 #define STAT_OK         (READY_STAT|SEEK_STAT)
 113 #define OK_STATUS(s)    (((s)&(STAT_OK|(BUSY_STAT|WRERR_STAT|ERR_STAT)))==STAT_OK)
 114
 115 static void recal_intr(void);
 116 static void bad_rw_intr(void);
 117
 118 static int reset;
 119 static int hd_error;
 120
 121 /*
 122  *  This struct defines the HD's and their types.
 123  */
 124 struct hd_i_struct {
 125         unsigned int head,sect,cyl,wpcom,lzone,ctl;
 126         int unit;
 127         int recalibrate;
 128         int special_op;
 129 };
 130
 131 #ifdef HD_TYPE
 132 static struct hd_i_struct hd_info[] = { HD_TYPE };
 133 static int NR_HD = ((sizeof (hd_info))/(sizeof (struct hd_i_struct)));
 134 #else
 135 static struct hd_i_struct hd_info[MAX_HD];
 136 static int NR_HD;
 137 #endif
 138
 139 static struct gendisk *hd_gendisk[MAX_HD];
 140
 141 static struct timer_list device_timer;
 142
 143 #define TIMEOUT_VALUE (6*HZ)
 144
 145 #define SET_TIMER                                                       \
 146         do {                                                            \
 147                 mod_timer(&device_timer, jiffies + TIMEOUT_VALUE);      \
 148         } while (0)
 149
 150 static void (*do_hd)(void) = NULL;
 151 #define SET_HANDLER(x) \
 152 if ((do_hd = (x)) != NULL) \
 153         SET_TIMER; \
 154 else \
 155         del_timer(&device_timer);
 156
 157
 158 #if (HD_DELAY > 0)
 159 unsigned long last_req;
 160
 161 unsigned long read_timer(void)
 162 {
 163         extern spinlock_t i8253_lock;
 164         unsigned long t, flags;
 165         int i;
 166
 167         spin_lock_irqsave(&i8253_lock, flags);
 168         t = jiffies * 11932;
 169         outb_p(0, 0x43);
 170         i = inb_p(0x40);
 171         i |= inb(0x40) << 8;
 172         spin_unlock_irqrestore(&i8253_lock, flags);
 173         return(t - i);
 174 }
 175 #endif
 176
 177 static void __init hd_setup(char *str, int *ints)
 178 {
 179         int hdind = 0;
 180
 181         if (ints[0] != 3)
 182                 return;
 183         if (hd_info[0].head != 0)
 184                 hdind=1;
 185         hd_info[hdind].head = ints[2];
 186         hd_info[hdind].sect = ints[3];
 187         hd_info[hdind].cyl = ints[1];
 188         hd_info[hdind].wpcom = 0;
 189         hd_info[hdind].lzone = ints[1];
 190         hd_info[hdind].ctl = (ints[2] > 8 ? 8 : 0);
 191         NR_HD = hdind+1;
 192 }
 193
 194 static void dump_status (const char *msg, unsigned int stat)
 195 {
 196         char *name = "hd?";
 197         if (CURRENT)
 198                 name = CURRENT->rq_disk->disk_name;
 199
 200 #ifdef VERBOSE_ERRORS
 201         printk("%s: %s: status=0x%02x { ", name, msg, stat & 0xff);
 202         if (stat & BUSY_STAT)   printk("Busy ");
 203         if (stat & READY_STAT)  printk("DriveReady ");
 204         if (stat & WRERR_STAT)  printk("WriteFault ");
 205         if (stat & SEEK_STAT)   printk("SeekComplete ");
 206         if (stat & DRQ_STAT)    printk("DataRequest ");
 207         if (stat & ECC_STAT)    printk("CorrectedError ");
 208         if (stat & INDEX_STAT)  printk("Index ");
 209         if (stat & ERR_STAT)    printk("Error ");
 210         printk("}\n");
 211         if ((stat & ERR_STAT) == 0) {
 212                 hd_error = 0;
 213         } else {
 214                 hd_error = inb(HD_ERROR);
 215                 printk("%s: %s: error=0x%02x { ", name, msg, hd_error & 0xff);
 216                 if (hd_error & BBD_ERR)         printk("BadSector ");
 217                 if (hd_error & ECC_ERR)         printk("UncorrectableError ");
 218                 if (hd_error & ID_ERR)          printk("SectorIdNotFound ");
 219                 if (hd_error & ABRT_ERR)        printk("DriveStatusError ");
 220                 if (hd_error & TRK0_ERR)        printk("TrackZeroNotFound ");
 221                 if (hd_error & MARK_ERR)        printk("AddrMarkNotFound ");
 222                 printk("}");
 223                 if (hd_error & (BBD_ERR|ECC_ERR|ID_ERR|MARK_ERR)) {
 224                         printk(", CHS=%d/%d/%d", (inb(HD_HCYL)<<8) + inb(HD_LCYL),
 225                                 inb(HD_CURRENT) & 0xf, inb(HD_SECTOR));
 226                         if (CURRENT)
 227                                 printk(", sector=%ld", CURRENT->sector);
 228                 }
 229                 printk("\n");
 230         }
 231 #else
 232         printk("%s: %s: status=0x%02x.\n", name, msg, stat & 0xff);
 233         if ((stat & ERR_STAT) == 0) {
 234                 hd_error = 0;
 235         } else {
 236                 hd_error = inb(HD_ERROR);
 237                 printk("%s: %s: error=0x%02x.\n", name, msg, hd_error & 0xff);
 238         }
 239 #endif
 240 }
 241
 242 static void check_status(void)
 243 {
 244         int i = inb_p(HD_STATUS);
 245
 246         if (!OK_STATUS(i)) {
 247                 dump_status("check_status", i);
 248                 bad_rw_intr();
 249         }
 250 }
 251
 252 static int controller_busy(void)
 253 {
 254         int retries = 100000;
 255         unsigned char status;
 256
 257         do {
 258                 status = inb_p(HD_STATUS);
 259         } while ((status & BUSY_STAT) && --retries);
 260         return status;
 261 }
 262
 263 static int status_ok(void)
 264 {
 265         unsigned char status = inb_p(HD_STATUS);
 266
 267         if (status & BUSY_STAT)
 268                 return 1;       /* Ancient, but does it make sense??? */
 269         if (status & WRERR_STAT)
 270                 return 0;
 271         if (!(status & READY_STAT))
 272                 return 0;
 273         if (!(status & SEEK_STAT))
 274                 return 0;
 275         return 1;
 276 }
 277
 278 static int controller_ready(unsigned int drive, unsigned int head)
 279 {
 280         int retry = 100;
 281
 282         do {
 283                 if (controller_busy() & BUSY_STAT)
 284                         return 0;
 285                 outb_p(0xA0 | (drive<<4) | head, HD_CURRENT);
 286                 if (status_ok())
 287                         return 1;
 288         } while (--retry);
 289         return 0;
 290 }
 291
 292
 293 static void hd_out(struct hd_i_struct *disk,
 294                    unsigned int nsect,
 295                    unsigned int sect,
 296                    unsigned int head,
 297                    unsigned int cyl,
 298                    unsigned int cmd,
 299                    void (*intr_addr)(void))
 300 {
 301         unsigned short port;
 302
 303 #if (HD_DELAY > 0)
 304         while (read_timer() - last_req < HD_DELAY)
 305                 /* nothing */;
 306 #endif
 307         if (reset)
 308                 return;
 309         if (!controller_ready(disk->unit, head)) {
 310                 reset = 1;
 311                 return;
 312         }
 313         SET_HANDLER(intr_addr);
 314         outb_p(disk->ctl,HD_CMD);
 315         port=HD_DATA;
 316         outb_p(disk->wpcom>>2,++port);
 317         outb_p(nsect,++port);
 318         outb_p(sect,++port);
 319         outb_p(cyl,++port);
 320         outb_p(cyl>>8,++port);
 321         outb_p(0xA0|(disk->unit<<4)|head,++port);
 322         outb_p(cmd,++port);
 323 }
 324
 325 static void hd_request (void);
 326
 327 static int drive_busy(void)
 328 {
 329         unsigned int i;
 330         unsigned char c;
 331
 332         for (i = 0; i < 500000 ; i++) {
 333                 c = inb_p(HD_STATUS);
 334                 if ((c & (BUSY_STAT | READY_STAT | SEEK_STAT)) == STAT_OK)
 335                         return 0;
 336         }
 337         dump_status("reset timed out", c);
 338         return 1;
 339 }
 340
 341 static void reset_controller(void)
 342 {
 343         int     i;
 344
 345         outb_p(4,HD_CMD);
 346         for(i = 0; i < 1000; i++) barrier();
 347         outb_p(hd_info[0].ctl & 0x0f,HD_CMD);
 348         for(i = 0; i < 1000; i++) barrier();
 349         if (drive_busy())
 350                 printk("hd: controller still busy\n");
 351         else if ((hd_error = inb(HD_ERROR)) != 1)
 352                 printk("hd: controller reset failed: %02x\n",hd_error);
 353 }
 354
 355 static void reset_hd(void)
 356 {
 357         static int i;
 358
 359 repeat:
 360         if (reset) {
 361                 reset = 0;
 362                 i = -1;
 363                 reset_controller();
 364         } else {
 365                 check_status();
 366                 if (reset)
 367                         goto repeat;
 368         }
 369         if (++i < NR_HD) {
 370                 struct hd_i_struct *disk = &hd_info[i];
 371                 disk->special_op = disk->recalibrate = 1;
 372                 hd_out(disk,disk->sect,disk->sect,disk->head-1,
 373                         disk->cyl,WIN_SPECIFY,&reset_hd);
 374                 if (reset)
 375                         goto repeat;
 376         } else
 377                 hd_request();
 378 }
 379
 380 /*
 381  * Ok, don't know what to do with the unexpected interrupts: on some machines
 382  * doing a reset and a retry seems to result in an eternal loop. Right now I
 383  * ignore it, and just set the timeout.
 384  *
 385  * On laptops (and "green" PCs), an unexpected interrupt occurs whenever the
 386  * drive enters "idle", "standby", or "sleep" mode, so if the status looks
 387  * "good", we just ignore the interrupt completely.
 388  */
 389 static void unexpected_hd_interrupt(void)
 390 {
 391         unsigned int stat = inb_p(HD_STATUS);
 392
 393         if (stat & (BUSY_STAT|DRQ_STAT|ECC_STAT|ERR_STAT)) {
 394                 dump_status ("unexpected interrupt", stat);
 395                 SET_TIMER;
 396         }
 397 }
 398
 399 /*
 400  * bad_rw_intr() now tries to be a bit smarter and does things
 401  * according to the error returned by the controller.
 402  * -Mika Liljeberg (liljeber@cs.Helsinki.FI)
 403  */
 404 static void bad_rw_intr(void)
 405 {
 406         struct request *req = CURRENT;
 407         if (req != NULL) {
 408                 struct hd_i_struct *disk = req->rq_disk->private_data;
 409                 if (++req->errors >= MAX_ERRORS || (hd_error & BBD_ERR)) {
 410                         end_request(req, 0);
 411                         disk->special_op = disk->recalibrate = 1;
 412                 } else if (req->errors % RESET_FREQ == 0)
 413                         reset = 1;
 414                 else if ((hd_error & TRK0_ERR) || req->errors % RECAL_FREQ == 0)
 415                         disk->special_op = disk->recalibrate = 1;
 416                 /* Otherwise just retry */
 417         }
 418 }
 419
 420 static inline int wait_DRQ(void)
 421 {
 422         int retries = 100000, stat;
 423
 424         while (--retries > 0)
 425                 if ((stat = inb_p(HD_STATUS)) & DRQ_STAT)
 426                         return 0;
 427         dump_status("wait_DRQ", stat);
 428         return -1;
 429 }
 430
 431 static void read_intr(void)
 432 {
 433         struct request *req;
 434         int i, retries = 100000;
 435
 436         do {
 437                 i = (unsigned) inb_p(HD_STATUS);
 438                 if (i & BUSY_STAT)
 439                         continue;
 440                 if (!OK_STATUS(i))
 441                         break;
 442                 if (i & DRQ_STAT)
 443                         goto ok_to_read;
 444         } while (--retries > 0);
 445         dump_status("read_intr", i);
 446         bad_rw_intr();
 447         hd_request();
 448         return;
 449 ok_to_read:
 450         req = CURRENT;
 451         insw(HD_DATA,req->buffer,256);
 452         req->sector++;
 453         req->buffer += 512;
 454         req->errors = 0;
 455         i = --req->nr_sectors;
 456         --req->current_nr_sectors;
 457 #ifdef DEBUG
 458         printk("%s: read: sector %ld, remaining = %ld, buffer=%p\n",
 459                 req->rq_disk->disk_name, req->sector, req->nr_sectors,
 460                 req->buffer+512));
 461 #endif
 462         if (req->current_nr_sectors <= 0)
 463                 end_request(req, 1);
 464         if (i > 0) {
 465                 SET_HANDLER(&read_intr);
 466                 return;
 467         }
 468         (void) inb_p(HD_STATUS);
 469 #if (HD_DELAY > 0)
 470         last_req = read_timer();
 471 #endif
 472         if (elv_next_request(QUEUE))
 473                 hd_request();
 474         return;
 475 }
 476
 477 static void write_intr(void)
 478 {
 479         struct request *req = CURRENT;
 480         int i;
 481         int retries = 100000;
 482
 483         do {
 484                 i = (unsigned) inb_p(HD_STATUS);
 485                 if (i & BUSY_STAT)
 486                         continue;
 487                 if (!OK_STATUS(i))
 488                         break;
 489                 if ((req->nr_sectors <= 1) || (i & DRQ_STAT))
 490                         goto ok_to_write;
 491         } while (--retries > 0);
 492         dump_status("write_intr", i);
 493         bad_rw_intr();
 494         hd_request();
 495         return;
 496 ok_to_write:
 497         req->sector++;
 498         i = --req->nr_sectors;
 499         --req->current_nr_sectors;
 500         req->buffer += 512;
 501         if (!i || (req->bio && req->current_nr_sectors <= 0))
 502                 end_request(req, 1);
 503         if (i > 0) {
 504                 SET_HANDLER(&write_intr);
 505                 outsw(HD_DATA,req->buffer,256);
 506                 local_irq_enable();
 507         } else {
 508 #if (HD_DELAY > 0)
 509                 last_req = read_timer();
 510 #endif
 511                 hd_request();
 512         }
 513         return;
 514 }
 515
 516 static void recal_intr(void)
 517 {
 518         check_status();
 519 #if (HD_DELAY > 0)
 520         last_req = read_timer();
 521 #endif
 522         hd_request();
 523 }
 524
 525 /*
 526  * This is another of the error-routines I don't know what to do with. The
 527  * best idea seems to just set reset, and start all over again.
 528  */
 529 static void hd_times_out(unsigned long dummy)
 530 {
 531         char *name;
 532
 533         do_hd = NULL;
 534
 535         if (!CURRENT)
 536                 return;
 537
 538         disable_irq(HD_IRQ);
 539         local_irq_enable();
 540         reset = 1;
 541         name = CURRENT->rq_disk->disk_name;
 542         printk("%s: timeout\n", name);
 543         if (++CURRENT->errors >= MAX_ERRORS) {
 544 #ifdef DEBUG
 545                 printk("%s: too many errors\n", name);
 546 #endif
 547                 end_request(CURRENT, 0);
 548         }
 549         local_irq_disable();
 550         hd_request();
 551         enable_irq(HD_IRQ);
 552 }
 553
 554 static int do_special_op(struct hd_i_struct *disk, struct request *req)
 555 {
 556         if (disk->recalibrate) {
 557                 disk->recalibrate = 0;
 558                 hd_out(disk,disk->sect,0,0,0,WIN_RESTORE,&recal_intr);
 559                 return reset;
 560         }
 561         if (disk->head > 16) {
 562                 printk ("%s: cannot handle device with more than 16 heads - giving up\n", req->rq_disk->disk_name);
 563                 end_request(req, 0);
 564         }
 565         disk->special_op = 0;
 566         return 1;
 567 }
 568
 569 /*
 570  * The driver enables interrupts as much as possible.  In order to do this,
 571  * (a) the device-interrupt is disabled before entering hd_request(),
 572  * and (b) the timeout-interrupt is disabled before the sti().
 573  *
 574  * Interrupts are still masked (by default) whenever we are exchanging
 575  * data/cmds with a drive, because some drives seem to have very poor
 576  * tolerance for latency during I/O. The IDE driver has support to unmask
 577  * interrupts for non-broken hardware, so use that driver if required.
 578  */
 579 static void hd_request(void)
 580 {
 581         unsigned int block, nsect, sec, track, head, cyl;
 582         struct hd_i_struct *disk;
 583         struct request *req;
 584
 585         if (do_hd)
 586                 return;
 587 repeat:
 588         del_timer(&device_timer);
 589         local_irq_enable();
 590
 591         req = CURRENT;
 592         if (!req) {
 593                 do_hd = NULL;
 594                 return;
 595         }
 596
 597         if (reset) {
 598                 local_irq_disable();
 599                 reset_hd();
 600                 return;
 601         }
 602         disk = req->rq_disk->private_data;
 603         block = req->sector;
 604         nsect = req->nr_sectors;
 605         if (block >= get_capacity(req->rq_disk) ||
 606             ((block+nsect) > get_capacity(req->rq_disk))) {
 607                 printk("%s: bad access: block=%d, count=%d\n",
 608                         req->rq_disk->disk_name, block, nsect);
 609                 end_request(req, 0);
 610                 goto repeat;
 611         }
 612
 613         if (disk->special_op) {
 614                 if (do_special_op(disk, req))
 615                         goto repeat;
 616                 return;
 617         }
 618         sec   = block % disk->sect + 1;
 619         track = block / disk->sect;
 620         head  = track % disk->head;
 621         cyl   = track / disk->head;
 622 #ifdef DEBUG
 623         printk("%s: %sing: CHS=%d/%d/%d, sectors=%d, buffer=%p\n",
 624                 req->rq_disk->disk_name, (req->cmd == READ)?"read":"writ",
 625                 cyl, head, sec, nsect, req->buffer);
 626 #endif
 627         if (req->flags & REQ_CMD) {
 628                 switch (rq_data_dir(req)) {
 629                 case READ:
 630                         hd_out(disk,nsect,sec,head,cyl,WIN_READ,&read_intr);
 631                         if (reset)
 632                                 goto repeat;
 633                         break;
 634                 case WRITE:
 635                         hd_out(disk,nsect,sec,head,cyl,WIN_WRITE,&write_intr);
 636                         if (reset)
 637                                 goto repeat;
 638                         if (wait_DRQ()) {
 639                                 bad_rw_intr();
 640                                 goto repeat;
 641                         }
 642                         outsw(HD_DATA,req->buffer,256);
 643                         break;
 644                 default:
 645                         printk("unknown hd-command\n");
 646                         end_request(req, 0);
 647                         break;
 648                 }
 649         }
 650 }
 651
 652 static void do_hd_request (request_queue_t * q)
 653 {
 654         disable_irq(HD_IRQ);
 655         hd_request();
 656         enable_irq(HD_IRQ);
 657 }
 658
 659 static int hd_ioctl(struct inode * inode, struct file * file,
 660         unsigned int cmd, unsigned long arg)
 661 {
 662         struct hd_i_struct *disk = inode->i_bdev->bd_disk->private_data;
 663         struct hd_geometry __user *loc = (struct hd_geometry __user *) arg;
 664         struct hd_geometry g;
 665
 666         if (cmd != HDIO_GETGEO)
 667                 return -EINVAL;
 668         if (!loc)
 669                 return -EINVAL;
 670         g.heads = disk->head;
 671         g.sectors = disk->sect;
 672         g.cylinders = disk->cyl;
 673         g.start = get_start_sect(inode->i_bdev);
 674         return copy_to_user(loc, &g, sizeof g) ? -EFAULT : 0;
 675 }
 676
 677 /*
 678  * Releasing a block device means we sync() it, so that it can safely
 679  * be forgotten about...
 680  */
 681
 682 static irqreturn_t hd_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 683 {
 684         void (*handler)(void) = do_hd;
 685
 686         do_hd = NULL;
 687         del_timer(&device_timer);
 688         if (!handler)
 689                 handler = unexpected_hd_interrupt;
 690         handler();
 691         local_irq_enable();
 692         return IRQ_HANDLED;
 693 }
 694
 695 static struct block_device_operations hd_fops = {
 696         .ioctl =        hd_ioctl,
 697 };
 698
 699 /*
 700  * This is the hard disk IRQ description. The SA_INTERRUPT in sa_flags
 701  * means we run the IRQ-handler with interrupts disabled:  this is bad for
 702  * interrupt latency, but anything else has led to problems on some
 703  * machines.
 704  *
 705  * We enable interrupts in some of the routines after making sure it's
 706  * safe.
 707  */
 708
 709 static int __init hd_init(void)
 710 {
 711         int drive;
 712
 713         if (register_blkdev(MAJOR_NR,"hd"))
 714                 return -1;
 715
 716         hd_queue = blk_init_queue(do_hd_request, &hd_lock);
 717         if (!hd_queue) {
 718                 unregister_blkdev(MAJOR_NR,"hd");
 719                 return -ENOMEM;
 720         }
 721
 722         blk_queue_max_sectors(hd_queue, 255);
 723         init_timer(&device_timer);
 724         device_timer.function = hd_times_out;
 725         blk_queue_hardsect_size(hd_queue, 512);
 726
 727 #ifdef __i386__
 728         if (!NR_HD) {
 729                 extern struct drive_info drive_info;
 730                 unsigned char *BIOS = (unsigned char *) &drive_info;
 731                 unsigned long flags;
 732                 int cmos_disks;
 733
 734                 for (drive=0 ; drive<2 ; drive++) {
 735                         hd_info[drive].cyl = *(unsigned short *) BIOS;
 736                         hd_info[drive].head = *(2+BIOS);
 737                         hd_info[drive].wpcom = *(unsigned short *) (5+BIOS);
 738                         hd_info[drive].ctl = *(8+BIOS);
 739                         hd_info[drive].lzone = *(unsigned short *) (12+BIOS);
 740                         hd_info[drive].sect = *(14+BIOS);
 741 #ifdef does_not_work_for_everybody_with_scsi_but_helps_ibm_vp
 742                         if (hd_info[drive].cyl && NR_HD == drive)
 743                                 NR_HD++;
 744 #endif
 745                         BIOS += 16;
 746                 }
 747
 748         /*
 749                 We query CMOS about hard disks : it could be that
 750                 we have a SCSI/ESDI/etc controller that is BIOS
 751                 compatible with ST-506, and thus showing up in our
 752                 BIOS table, but not register compatible, and therefore
 753                 not present in CMOS.
 754
 755                 Furthermore, we will assume that our ST-506 drives
 756                 <if any> are the primary drives in the system, and
 757                 the ones reflected as drive 1 or 2.
 758
 759                 The first drive is stored in the high nibble of CMOS
 760                 byte 0x12, the second in the low nibble.  This will be
 761                 either a 4 bit drive type or 0xf indicating use byte 0x19
 762                 for an 8 bit type, drive 1, 0x1a for drive 2 in CMOS.
 763
 764                 Needless to say, a non-zero value means we have
 765                 an AT controller hard disk for that drive.
 766
 767                 Currently the rtc_lock is a bit academic since this
 768                 driver is non-modular, but someday... ?         Paul G.
 769         */
 770
 771                 spin_lock_irqsave(&rtc_lock, flags);
 772                 cmos_disks = CMOS_READ(0x12);
 773                 spin_unlock_irqrestore(&rtc_lock, flags);
 774
 775                 if (cmos_disks & 0xf0) {
 776                         if (cmos_disks & 0x0f)
 777                                 NR_HD = 2;
 778                         else
 779                                 NR_HD = 1;
 780                 }
 781         }
 782 #endif /* __i386__ */
 783 #ifdef __arm__
 784         if (!NR_HD) {
 785                 /* We don't know anything about the drive.  This means
 786                  * that you *MUST* specify the drive parameters to the
 787                  * kernel yourself.
 788                  */
 789                 printk("hd: no drives specified - use hd=cyl,head,sectors"
 790                         " on kernel command line\n");
 791         }
 792 #endif
 793         if (!NR_HD)
 794                 goto out;
 795
 796         for (drive=0 ; drive < NR_HD ; drive++) {
 797                 struct gendisk *disk = alloc_disk(64);
 798                 struct hd_i_struct *p = &hd_info[drive];
 799                 if (!disk)
 800                         goto Enomem;
 801                 disk->major = MAJOR_NR;
 802                 disk->first_minor = drive << 6;
 803                 disk->fops = &hd_fops;
 804                 sprintf(disk->disk_name, "hd%c", 'a'+drive);
 805                 disk->private_data = p;
 806                 set_capacity(disk, p->head * p->sect * p->cyl);
 807                 disk->queue = hd_queue;
 808                 p->unit = drive;
 809                 hd_gendisk[drive] = disk;
 810                 printk ("%s: %luMB, CHS=%d/%d/%d\n",
 811                         disk->disk_name, (unsigned long)get_capacity(disk)/2048,
 812                         p->cyl, p->head, p->sect);
 813         }
 814
 815         if (request_irq(HD_IRQ, hd_interrupt, SA_INTERRUPT, "hd", NULL)) {
 816                 printk("hd: unable to get IRQ%d for the hard disk driver\n",
 817                         HD_IRQ);
 818                 goto out1;
 819         }
 820         if (!request_region(HD_DATA, 8, "hd")) {
 821                 printk(KERN_WARNING "hd: port 0x%x busy\n", HD_DATA);
 822                 goto out2;
 823         }
 824         if (!request_region(HD_CMD, 1, "hd(cmd)")) {
 825                 printk(KERN_WARNING "hd: port 0x%x busy\n", HD_CMD);
 826                 goto out3;
 827         }
 828
 829         /* Let them fly */
 830         for(drive=0; drive < NR_HD; drive++)
 831                 add_disk(hd_gendisk[drive]);
 832
 833         return 0;
 834
 835 out3:
 836         release_region(HD_DATA, 8);
 837 out2:
 838         free_irq(HD_IRQ, NULL);
 839 out1:
 840         for (drive = 0; drive < NR_HD; drive++)
 841                 put_disk(hd_gendisk[drive]);
 842         NR_HD = 0;
 843 out:
 844         del_timer(&device_timer);
 845         unregister_blkdev(MAJOR_NR,"hd");
 846         blk_cleanup_queue(hd_queue);
 847         return -1;
 848 Enomem:
 849         while (drive--)
 850                 put_disk(hd_gendisk[drive]);
 851         goto out;
 852 }
 853
 854 static int __init parse_hd_setup (char *line) {
 855         int ints[6];
 856
 857         (void) get_options(line, ARRAY_SIZE(ints), ints);
 858         hd_setup(NULL, ints);
 859
 860         return 1;
 861 }
 862 __setup("hd=", parse_hd_setup);
 863
 864 module_init(hd_init);