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
 160 #include <asm/i8253.h>
 161
 162 unsigned long last_req;
 163
 164 unsigned long read_timer(void)
 165 {
 166         unsigned long t, flags;
 167         int i;
 168
 169         spin_lock_irqsave(&i8253_lock, flags);
 170         t = jiffies * 11932;
 171         outb_p(0, 0x43);
 172         i = inb_p(0x40);
 173         i |= inb(0x40) << 8;
 174         spin_unlock_irqrestore(&i8253_lock, flags);
 175         return(t - i);
 176 }
 177 #endif
 178
 179 static void __init hd_setup(char *str, int *ints)
 180 {
 181         int hdind = 0;
 182
 183         if (ints[0] != 3)
 184                 return;
 185         if (hd_info[0].head != 0)
 186                 hdind=1;
 187         hd_info[hdind].head = ints[2];
 188         hd_info[hdind].sect = ints[3];
 189         hd_info[hdind].cyl = ints[1];
 190         hd_info[hdind].wpcom = 0;
 191         hd_info[hdind].lzone = ints[1];
 192         hd_info[hdind].ctl = (ints[2] > 8 ? 8 : 0);
 193         NR_HD = hdind+1;
 194 }
 195
 196 static void dump_status (const char *msg, unsigned int stat)
 197 {
 198         char *name = "hd?";
 199         if (CURRENT)
 200                 name = CURRENT->rq_disk->disk_name;
 201
 202 #ifdef VERBOSE_ERRORS
 203         printk("%s: %s: status=0x%02x { ", name, msg, stat & 0xff);
 204         if (stat & BUSY_STAT)   printk("Busy ");
 205         if (stat & READY_STAT)  printk("DriveReady ");
 206         if (stat & WRERR_STAT)  printk("WriteFault ");
 207         if (stat & SEEK_STAT)   printk("SeekComplete ");
 208         if (stat & DRQ_STAT)    printk("DataRequest ");
 209         if (stat & ECC_STAT)    printk("CorrectedError ");
 210         if (stat & INDEX_STAT)  printk("Index ");
 211         if (stat & ERR_STAT)    printk("Error ");
 212         printk("}\n");
 213         if ((stat & ERR_STAT) == 0) {
 214                 hd_error = 0;
 215         } else {
 216                 hd_error = inb(HD_ERROR);
 217                 printk("%s: %s: error=0x%02x { ", name, msg, hd_error & 0xff);
 218                 if (hd_error & BBD_ERR)         printk("BadSector ");
 219                 if (hd_error & ECC_ERR)         printk("UncorrectableError ");
 220                 if (hd_error & ID_ERR)          printk("SectorIdNotFound ");
 221                 if (hd_error & ABRT_ERR)        printk("DriveStatusError ");
 222                 if (hd_error & TRK0_ERR)        printk("TrackZeroNotFound ");
 223                 if (hd_error & MARK_ERR)        printk("AddrMarkNotFound ");
 224                 printk("}");
 225                 if (hd_error & (BBD_ERR|ECC_ERR|ID_ERR|MARK_ERR)) {
 226                         printk(", CHS=%d/%d/%d", (inb(HD_HCYL)<<8) + inb(HD_LCYL),
 227                                 inb(HD_CURRENT) & 0xf, inb(HD_SECTOR));
 228                         if (CURRENT)
 229                                 printk(", sector=%ld", CURRENT->sector);
 230                 }
 231                 printk("\n");
 232         }
 233 #else
 234         printk("%s: %s: status=0x%02x.\n", name, msg, stat & 0xff);
 235         if ((stat & ERR_STAT) == 0) {
 236                 hd_error = 0;
 237         } else {
 238                 hd_error = inb(HD_ERROR);
 239                 printk("%s: %s: error=0x%02x.\n", name, msg, hd_error & 0xff);
 240         }
 241 #endif
 242 }
 243
 244 static void check_status(void)
 245 {
 246         int i = inb_p(HD_STATUS);
 247
 248         if (!OK_STATUS(i)) {
 249                 dump_status("check_status", i);
 250                 bad_rw_intr();
 251         }
 252 }
 253
 254 static int controller_busy(void)
 255 {
 256         int retries = 100000;
 257         unsigned char status;
 258
 259         do {
 260                 status = inb_p(HD_STATUS);
 261         } while ((status & BUSY_STAT) && --retries);
 262         return status;
 263 }
 264
 265 static int status_ok(void)
 266 {
 267         unsigned char status = inb_p(HD_STATUS);
 268
 269         if (status & BUSY_STAT)
 270                 return 1;       /* Ancient, but does it make sense??? */
 271         if (status & WRERR_STAT)
 272                 return 0;
 273         if (!(status & READY_STAT))
 274                 return 0;
 275         if (!(status & SEEK_STAT))
 276                 return 0;
 277         return 1;
 278 }
 279
 280 static int controller_ready(unsigned int drive, unsigned int head)
 281 {
 282         int retry = 100;
 283
 284         do {
 285                 if (controller_busy() & BUSY_STAT)
 286                         return 0;
 287                 outb_p(0xA0 | (drive<<4) | head, HD_CURRENT);
 288                 if (status_ok())
 289                         return 1;
 290         } while (--retry);
 291         return 0;
 292 }
 293
 294
 295 static void hd_out(struct hd_i_struct *disk,
 296                    unsigned int nsect,
 297                    unsigned int sect,
 298                    unsigned int head,
 299                    unsigned int cyl,
 300                    unsigned int cmd,
 301                    void (*intr_addr)(void))
 302 {
 303         unsigned short port;
 304
 305 #if (HD_DELAY > 0)
 306         while (read_timer() - last_req < HD_DELAY)
 307                 /* nothing */;
 308 #endif
 309         if (reset)
 310                 return;
 311         if (!controller_ready(disk->unit, head)) {
 312                 reset = 1;
 313                 return;
 314         }
 315         SET_HANDLER(intr_addr);
 316         outb_p(disk->ctl,HD_CMD);
 317         port=HD_DATA;
 318         outb_p(disk->wpcom>>2,++port);
 319         outb_p(nsect,++port);
 320         outb_p(sect,++port);
 321         outb_p(cyl,++port);
 322         outb_p(cyl>>8,++port);
 323         outb_p(0xA0|(disk->unit<<4)|head,++port);
 324         outb_p(cmd,++port);
 325 }
 326
 327 static void hd_request (void);
 328
 329 static int drive_busy(void)
 330 {
 331         unsigned int i;
 332         unsigned char c;
 333
 334         for (i = 0; i < 500000 ; i++) {
 335                 c = inb_p(HD_STATUS);
 336                 if ((c & (BUSY_STAT | READY_STAT | SEEK_STAT)) == STAT_OK)
 337                         return 0;
 338         }
 339         dump_status("reset timed out", c);
 340         return 1;
 341 }
 342
 343 static void reset_controller(void)
 344 {
 345         int     i;
 346
 347         outb_p(4,HD_CMD);
 348         for(i = 0; i < 1000; i++) barrier();
 349         outb_p(hd_info[0].ctl & 0x0f,HD_CMD);
 350         for(i = 0; i < 1000; i++) barrier();
 351         if (drive_busy())
 352                 printk("hd: controller still busy\n");
 353         else if ((hd_error = inb(HD_ERROR)) != 1)
 354                 printk("hd: controller reset failed: %02x\n",hd_error);
 355 }
 356
 357 static void reset_hd(void)
 358 {
 359         static int i;
 360
 361 repeat:
 362         if (reset) {
 363                 reset = 0;
 364                 i = -1;
 365                 reset_controller();
 366         } else {
 367                 check_status();
 368                 if (reset)
 369                         goto repeat;
 370         }
 371         if (++i < NR_HD) {
 372                 struct hd_i_struct *disk = &hd_info[i];
 373                 disk->special_op = disk->recalibrate = 1;
 374                 hd_out(disk,disk->sect,disk->sect,disk->head-1,
 375                         disk->cyl,WIN_SPECIFY,&reset_hd);
 376                 if (reset)
 377                         goto repeat;
 378         } else
 379                 hd_request();
 380 }
 381
 382 /*
 383  * Ok, don't know what to do with the unexpected interrupts: on some machines
 384  * doing a reset and a retry seems to result in an eternal loop. Right now I
 385  * ignore it, and just set the timeout.
 386  *
 387  * On laptops (and "green" PCs), an unexpected interrupt occurs whenever the
 388  * drive enters "idle", "standby", or "sleep" mode, so if the status looks
 389  * "good", we just ignore the interrupt completely.
 390  */
 391 static void unexpected_hd_interrupt(void)
 392 {
 393         unsigned int stat = inb_p(HD_STATUS);
 394
 395         if (stat & (BUSY_STAT|DRQ_STAT|ECC_STAT|ERR_STAT)) {
 396                 dump_status ("unexpected interrupt", stat);
 397                 SET_TIMER;
 398         }
 399 }
 400
 401 /*
 402  * bad_rw_intr() now tries to be a bit smarter and does things
 403  * according to the error returned by the controller.
 404  * -Mika Liljeberg (liljeber@cs.Helsinki.FI)
 405  */
 406 static void bad_rw_intr(void)
 407 {
 408         struct request *req = CURRENT;
 409         if (req != NULL) {
 410                 struct hd_i_struct *disk = req->rq_disk->private_data;
 411                 if (++req->errors >= MAX_ERRORS || (hd_error & BBD_ERR)) {
 412                         end_request(req, 0);
 413                         disk->special_op = disk->recalibrate = 1;
 414                 } else if (req->errors % RESET_FREQ == 0)
 415                         reset = 1;
 416                 else if ((hd_error & TRK0_ERR) || req->errors % RECAL_FREQ == 0)
 417                         disk->special_op = disk->recalibrate = 1;
 418                 /* Otherwise just retry */
 419         }
 420 }
 421
 422 static inline int wait_DRQ(void)
 423 {
 424         int retries = 100000, stat;
 425
 426         while (--retries > 0)
 427                 if ((stat = inb_p(HD_STATUS)) & DRQ_STAT)
 428                         return 0;
 429         dump_status("wait_DRQ", stat);
 430         return -1;
 431 }
 432
 433 static void read_intr(void)
 434 {
 435         struct request *req;
 436         int i, retries = 100000;
 437
 438         do {
 439                 i = (unsigned) inb_p(HD_STATUS);
 440                 if (i & BUSY_STAT)
 441                         continue;
 442                 if (!OK_STATUS(i))
 443                         break;
 444                 if (i & DRQ_STAT)
 445                         goto ok_to_read;
 446         } while (--retries > 0);
 447         dump_status("read_intr", i);
 448         bad_rw_intr();
 449         hd_request();
 450         return;
 451 ok_to_read:
 452         req = CURRENT;
 453         insw(HD_DATA,req->buffer,256);
 454         req->sector++;
 455         req->buffer += 512;
 456         req->errors = 0;
 457         i = --req->nr_sectors;
 458         --req->current_nr_sectors;
 459 #ifdef DEBUG
 460         printk("%s: read: sector %ld, remaining = %ld, buffer=%p\n",
 461                 req->rq_disk->disk_name, req->sector, req->nr_sectors,
 462                 req->buffer+512));
 463 #endif
 464         if (req->current_nr_sectors <= 0)
 465                 end_request(req, 1);
 466         if (i > 0) {
 467                 SET_HANDLER(&read_intr);
 468                 return;
 469         }
 470         (void) inb_p(HD_STATUS);
 471 #if (HD_DELAY > 0)
 472         last_req = read_timer();
 473 #endif
 474         if (elv_next_request(QUEUE))
 475                 hd_request();
 476         return;
 477 }
 478
 479 static void write_intr(void)
 480 {
 481         struct request *req = CURRENT;
 482         int i;
 483         int retries = 100000;
 484
 485         do {
 486                 i = (unsigned) inb_p(HD_STATUS);
 487                 if (i & BUSY_STAT)
 488                         continue;
 489                 if (!OK_STATUS(i))
 490                         break;
 491                 if ((req->nr_sectors <= 1) || (i & DRQ_STAT))
 492                         goto ok_to_write;
 493         } while (--retries > 0);
 494         dump_status("write_intr", i);
 495         bad_rw_intr();
 496         hd_request();
 497         return;
 498 ok_to_write:
 499         req->sector++;
 500         i = --req->nr_sectors;
 501         --req->current_nr_sectors;
 502         req->buffer += 512;
 503         if (!i || (req->bio && req->current_nr_sectors <= 0))
 504                 end_request(req, 1);
 505         if (i > 0) {
 506                 SET_HANDLER(&write_intr);
 507                 outsw(HD_DATA,req->buffer,256);
 508                 local_irq_enable();
 509         } else {
 510 #if (HD_DELAY > 0)
 511                 last_req = read_timer();
 512 #endif
 513                 hd_request();
 514         }
 515         return;
 516 }
 517
 518 static void recal_intr(void)
 519 {
 520         check_status();
 521 #if (HD_DELAY > 0)
 522         last_req = read_timer();
 523 #endif
 524         hd_request();
 525 }
 526
 527 /*
 528  * This is another of the error-routines I don't know what to do with. The
 529  * best idea seems to just set reset, and start all over again.
 530  */
 531 static void hd_times_out(unsigned long dummy)
 532 {
 533         char *name;
 534
 535         do_hd = NULL;
 536
 537         if (!CURRENT)
 538                 return;
 539
 540         disable_irq(HD_IRQ);
 541         local_irq_enable();
 542         reset = 1;
 543         name = CURRENT->rq_disk->disk_name;
 544         printk("%s: timeout\n", name);
 545         if (++CURRENT->errors >= MAX_ERRORS) {
 546 #ifdef DEBUG
 547                 printk("%s: too many errors\n", name);
 548 #endif
 549                 end_request(CURRENT, 0);
 550         }
 551         local_irq_disable();
 552         hd_request();
 553         enable_irq(HD_IRQ);
 554 }
 555
 556 static int do_special_op(struct hd_i_struct *disk, struct request *req)
 557 {
 558         if (disk->recalibrate) {
 559                 disk->recalibrate = 0;
 560                 hd_out(disk,disk->sect,0,0,0,WIN_RESTORE,&recal_intr);
 561                 return reset;
 562         }
 563         if (disk->head > 16) {
 564                 printk ("%s: cannot handle device with more than 16 heads - giving up\n", req->rq_disk->disk_name);
 565                 end_request(req, 0);
 566         }
 567         disk->special_op = 0;
 568         return 1;
 569 }
 570
 571 /*
 572  * The driver enables interrupts as much as possible.  In order to do this,
 573  * (a) the device-interrupt is disabled before entering hd_request(),
 574  * and (b) the timeout-interrupt is disabled before the sti().
 575  *
 576  * Interrupts are still masked (by default) whenever we are exchanging
 577  * data/cmds with a drive, because some drives seem to have very poor
 578  * tolerance for latency during I/O. The IDE driver has support to unmask
 579  * interrupts for non-broken hardware, so use that driver if required.
 580  */
 581 static void hd_request(void)
 582 {
 583         unsigned int block, nsect, sec, track, head, cyl;
 584         struct hd_i_struct *disk;
 585         struct request *req;
 586
 587         if (do_hd)
 588                 return;
 589 repeat:
 590         del_timer(&device_timer);
 591         local_irq_enable();
 592
 593         req = CURRENT;
 594         if (!req) {
 595                 do_hd = NULL;
 596                 return;
 597         }
 598
 599         if (reset) {
 600                 local_irq_disable();
 601                 reset_hd();
 602                 return;
 603         }
 604         disk = req->rq_disk->private_data;
 605         block = req->sector;
 606         nsect = req->nr_sectors;
 607         if (block >= get_capacity(req->rq_disk) ||
 608             ((block+nsect) > get_capacity(req->rq_disk))) {
 609                 printk("%s: bad access: block=%d, count=%d\n",
 610                         req->rq_disk->disk_name, block, nsect);
 611                 end_request(req, 0);
 612                 goto repeat;
 613         }
 614
 615         if (disk->special_op) {
 616                 if (do_special_op(disk, req))
 617                         goto repeat;
 618                 return;
 619         }
 620         sec   = block % disk->sect + 1;
 621         track = block / disk->sect;
 622         head  = track % disk->head;
 623         cyl   = track / disk->head;
 624 #ifdef DEBUG
 625         printk("%s: %sing: CHS=%d/%d/%d, sectors=%d, buffer=%p\n",
 626                 req->rq_disk->disk_name, (req->cmd == READ)?"read":"writ",
 627                 cyl, head, sec, nsect, req->buffer);
 628 #endif
 629         if (blk_fs_request(req)) {
 630                 switch (rq_data_dir(req)) {
 631                 case READ:
 632                         hd_out(disk,nsect,sec,head,cyl,WIN_READ,&read_intr);
 633                         if (reset)
 634                                 goto repeat;
 635                         break;
 636                 case WRITE:
 637                         hd_out(disk,nsect,sec,head,cyl,WIN_WRITE,&write_intr);
 638                         if (reset)
 639                                 goto repeat;
 640                         if (wait_DRQ()) {
 641                                 bad_rw_intr();
 642                                 goto repeat;
 643                         }
 644                         outsw(HD_DATA,req->buffer,256);
 645                         break;
 646                 default:
 647                         printk("unknown hd-command\n");
 648                         end_request(req, 0);
 649                         break;
 650                 }
 651         }
 652 }
 653
 654 static void do_hd_request (request_queue_t * q)
 655 {
 656         disable_irq(HD_IRQ);
 657         hd_request();
 658         enable_irq(HD_IRQ);
 659 }
 660
 661 static int hd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 662 {
 663         struct hd_i_struct *disk = bdev->bd_disk->private_data;
 664
 665         geo->heads = disk->head;
 666         geo->sectors = disk->sect;
 667         geo->cylinders = disk->cyl;
 668         return 0;
 669 }
 670
 671 /*
 672  * Releasing a block device means we sync() it, so that it can safely
 673  * be forgotten about...
 674  */
 675
 676 static irqreturn_t hd_interrupt(int irq, void *dev_id)
 677 {
 678         void (*handler)(void) = do_hd;
 679
 680         do_hd = NULL;
 681         del_timer(&device_timer);
 682         if (!handler)
 683                 handler = unexpected_hd_interrupt;
 684         handler();
 685         local_irq_enable();
 686         return IRQ_HANDLED;
 687 }
 688
 689 static struct block_device_operations hd_fops = {
 690         .getgeo =       hd_getgeo,
 691 };
 692
 693 /*
 694  * This is the hard disk IRQ description. The IRQF_DISABLED in sa_flags
 695  * means we run the IRQ-handler with interrupts disabled:  this is bad for
 696  * interrupt latency, but anything else has led to problems on some
 697  * machines.
 698  *
 699  * We enable interrupts in some of the routines after making sure it's
 700  * safe.
 701  */
 702
 703 static int __init hd_init(void)
 704 {
 705         int drive;
 706
 707         if (register_blkdev(MAJOR_NR,"hd"))
 708                 return -1;
 709
 710         hd_queue = blk_init_queue(do_hd_request, &hd_lock);
 711         if (!hd_queue) {
 712                 unregister_blkdev(MAJOR_NR,"hd");
 713                 return -ENOMEM;
 714         }
 715
 716         blk_queue_max_sectors(hd_queue, 255);
 717         init_timer(&device_timer);
 718         device_timer.function = hd_times_out;
 719         blk_queue_hardsect_size(hd_queue, 512);
 720
 721 #ifdef __i386__
 722         if (!NR_HD) {
 723                 extern struct drive_info drive_info;
 724                 unsigned char *BIOS = (unsigned char *) &drive_info;
 725                 unsigned long flags;
 726                 int cmos_disks;
 727
 728                 for (drive=0 ; drive<2 ; drive++) {
 729                         hd_info[drive].cyl = *(unsigned short *) BIOS;
 730                         hd_info[drive].head = *(2+BIOS);
 731                         hd_info[drive].wpcom = *(unsigned short *) (5+BIOS);
 732                         hd_info[drive].ctl = *(8+BIOS);
 733                         hd_info[drive].lzone = *(unsigned short *) (12+BIOS);
 734                         hd_info[drive].sect = *(14+BIOS);
 735 #ifdef does_not_work_for_everybody_with_scsi_but_helps_ibm_vp
 736                         if (hd_info[drive].cyl && NR_HD == drive)
 737                                 NR_HD++;
 738 #endif
 739                         BIOS += 16;
 740                 }
 741
 742         /*
 743                 We query CMOS about hard disks : it could be that
 744                 we have a SCSI/ESDI/etc controller that is BIOS
 745                 compatible with ST-506, and thus showing up in our
 746                 BIOS table, but not register compatible, and therefore
 747                 not present in CMOS.
 748
 749                 Furthermore, we will assume that our ST-506 drives
 750                 <if any> are the primary drives in the system, and
 751                 the ones reflected as drive 1 or 2.
 752
 753                 The first drive is stored in the high nibble of CMOS
 754                 byte 0x12, the second in the low nibble.  This will be
 755                 either a 4 bit drive type or 0xf indicating use byte 0x19
 756                 for an 8 bit type, drive 1, 0x1a for drive 2 in CMOS.
 757
 758                 Needless to say, a non-zero value means we have
 759                 an AT controller hard disk for that drive.
 760
 761                 Currently the rtc_lock is a bit academic since this
 762                 driver is non-modular, but someday... ?         Paul G.
 763         */
 764
 765                 spin_lock_irqsave(&rtc_lock, flags);
 766                 cmos_disks = CMOS_READ(0x12);
 767                 spin_unlock_irqrestore(&rtc_lock, flags);
 768
 769                 if (cmos_disks & 0xf0) {
 770                         if (cmos_disks & 0x0f)
 771                                 NR_HD = 2;
 772                         else
 773                                 NR_HD = 1;
 774                 }
 775         }
 776 #endif /* __i386__ */
 777 #ifdef __arm__
 778         if (!NR_HD) {
 779                 /* We don't know anything about the drive.  This means
 780                  * that you *MUST* specify the drive parameters to the
 781                  * kernel yourself.
 782                  */
 783                 printk("hd: no drives specified - use hd=cyl,head,sectors"
 784                         " on kernel command line\n");
 785         }
 786 #endif
 787         if (!NR_HD)
 788                 goto out;
 789
 790         for (drive=0 ; drive < NR_HD ; drive++) {
 791                 struct gendisk *disk = alloc_disk(64);
 792                 struct hd_i_struct *p = &hd_info[drive];
 793                 if (!disk)
 794                         goto Enomem;
 795                 disk->major = MAJOR_NR;
 796                 disk->first_minor = drive << 6;
 797                 disk->fops = &hd_fops;
 798                 sprintf(disk->disk_name, "hd%c", 'a'+drive);
 799                 disk->private_data = p;
 800                 set_capacity(disk, p->head * p->sect * p->cyl);
 801                 disk->queue = hd_queue;
 802                 p->unit = drive;
 803                 hd_gendisk[drive] = disk;
 804                 printk ("%s: %luMB, CHS=%d/%d/%d\n",
 805                         disk->disk_name, (unsigned long)get_capacity(disk)/2048,
 806                         p->cyl, p->head, p->sect);
 807         }
 808
 809         if (request_irq(HD_IRQ, hd_interrupt, IRQF_DISABLED, "hd", NULL)) {
 810                 printk("hd: unable to get IRQ%d for the hard disk driver\n",
 811                         HD_IRQ);
 812                 goto out1;
 813         }
 814         if (!request_region(HD_DATA, 8, "hd")) {
 815                 printk(KERN_WARNING "hd: port 0x%x busy\n", HD_DATA);
 816                 goto out2;
 817         }
 818         if (!request_region(HD_CMD, 1, "hd(cmd)")) {
 819                 printk(KERN_WARNING "hd: port 0x%x busy\n", HD_CMD);
 820                 goto out3;
 821         }
 822
 823         /* Let them fly */
 824         for(drive=0; drive < NR_HD; drive++)
 825                 add_disk(hd_gendisk[drive]);
 826
 827         return 0;
 828
 829 out3:
 830         release_region(HD_DATA, 8);
 831 out2:
 832         free_irq(HD_IRQ, NULL);
 833 out1:
 834         for (drive = 0; drive < NR_HD; drive++)
 835                 put_disk(hd_gendisk[drive]);
 836         NR_HD = 0;
 837 out:
 838         del_timer(&device_timer);
 839         unregister_blkdev(MAJOR_NR,"hd");
 840         blk_cleanup_queue(hd_queue);
 841         return -1;
 842 Enomem:
 843         while (drive--)
 844                 put_disk(hd_gendisk[drive]);
 845         goto out;
 846 }
 847
 848 static int __init parse_hd_setup (char *line) {
 849         int ints[6];
 850
 851         (void) get_options(line, ARRAY_SIZE(ints), ints);
 852         hd_setup(NULL, ints);
 853
 854         return 1;
 855 }
 856 __setup("hd=", parse_hd_setup);
 857
 858 module_init(hd_init);