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hd.c

/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This is the low-level hd interrupt support. It traverses the
 * request-list, using interrupts to jump between functions. As
 * all the functions are called within interrupts, we may not
 * sleep. Special care is recommended.
 *
 *  modified by Drew Eckhardt to check nr of hd's from the CMOS.
 *
 *  Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug
 *  in the early extended-partition checks and added DM partitions
 *
 *  IRQ-unmask, drive-id, multiple-mode, support for ">16 heads",
 *  and general streamlining by Mark Lord.
 *
 *  Removed 99% of above. Use Mark's ide driver for those options.
 *  This is now a lightweight ST-506 driver. (Paul Gortmaker)
 *
 *  Modified 1995 Russell King for ARM processor.
 *
 *  Bugfix: max_sectors must be <= 255 or the wheels tend to come
 *  off in a hurry once you queue things up - Paul G. 02/2001
 */

/* Uncomment the following if you want verbose error reports. */
/* #define VERBOSE_ERRORS */

#include <linux/blkdev.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/genhd.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/ioport.h>
#include <linux/mc146818rtc.h> /* CMOS defines */
#include <linux/init.h>
#include <linux/blkpg.h>
#include <linux/hdreg.h>

#define REALLY_SLOW_IO
#include <asm/system.h>
#include <asm/io.h>
#include <asm/uaccess.h>

#ifdef __arm__
#undef  HD_IRQ
#endif
#include <asm/irq.h>
#ifdef __arm__
#define HD_IRQ IRQ_HARDDISK
#endif

/* Hd controller regster ports */

#define HD_DATA         0x1f0       /* _CTL when writing */
#define HD_ERROR  0x1f1       /* see err-bits */
#define HD_NSECTOR      0x1f2       /* nr of sectors to read/write */
#define HD_SECTOR 0x1f3       /* starting sector */
#define HD_LCYL         0x1f4       /* starting cylinder */
#define HD_HCYL         0x1f5       /* high byte of starting cyl */
#define HD_CURRENT      0x1f6       /* 101dhhhh , d=drive, hhhh=head */
#define HD_STATUS 0x1f7       /* see status-bits */
#define HD_FEATURE      HD_ERROR    /* same io address, read=error, write=feature */
#define HD_PRECOMP      HD_FEATURE  /* obsolete use of this port - predates IDE */
#define HD_COMMAND      HD_STATUS   /* same io address, read=status, write=cmd */

#define HD_CMD          0x3f6       /* used for resets */
#define HD_ALTSTATUS    0x3f6       /* same as HD_STATUS but doesn't clear irq */

/* Bits of HD_STATUS */
#define ERR_STAT        0x01
#define INDEX_STAT            0x02
#define ECC_STAT        0x04  /* Corrected error */
#define DRQ_STAT        0x08
#define SEEK_STAT       0x10
#define SERVICE_STAT          SEEK_STAT
#define WRERR_STAT            0x20
#define READY_STAT            0x40
#define BUSY_STAT       0x80

/* Bits for HD_ERROR */
#define MARK_ERR        0x01  /* Bad address mark */
#define TRK0_ERR        0x02  /* couldn't find track 0 */
#define ABRT_ERR        0x04  /* Command aborted */
#define MCR_ERR               0x08  /* media change request */
#define ID_ERR                0x10  /* ID field not found */
#define MC_ERR                0x20  /* media changed */
#define ECC_ERR               0x40  /* Uncorrectable ECC error */
#define BBD_ERR               0x80  /* pre-EIDE meaning:  block marked bad */
#define ICRC_ERR        0x80  /* new meaning:  CRC error during transfer */

static DEFINE_SPINLOCK(hd_lock);
static struct request_queue *hd_queue;

#define MAJOR_NR HD_MAJOR
#define QUEUE (hd_queue)
#define CURRENT elv_next_request(hd_queue)

#define TIMEOUT_VALUE   (6*HZ)
#define     HD_DELAY    0

#define MAX_ERRORS     16     /* Max read/write errors/sector */
#define RESET_FREQ      8     /* Reset controller every 8th retry */
#define RECAL_FREQ      4     /* Recalibrate every 4th retry */
#define MAX_HD          2

#define STAT_OK         (READY_STAT|SEEK_STAT)
#define OK_STATUS(s)    (((s)&(STAT_OK|(BUSY_STAT|WRERR_STAT|ERR_STAT)))==STAT_OK)

static void recal_intr(void);
static void bad_rw_intr(void);

static int reset;
static int hd_error;

/*
 *  This struct defines the HD's and their types.
 */
struct hd_i_struct {
      unsigned int head,sect,cyl,wpcom,lzone,ctl;
      int unit;
      int recalibrate;
      int special_op;
};
      
#ifdef HD_TYPE
static struct hd_i_struct hd_info[] = { HD_TYPE };
static int NR_HD = ARRAY_SIZE(hd_info);
#else
static struct hd_i_struct hd_info[MAX_HD];
static int NR_HD;
#endif

static struct gendisk *hd_gendisk[MAX_HD];

static struct timer_list device_timer;

#define TIMEOUT_VALUE (6*HZ)

#define SET_TIMER                                     \
      do {                                            \
            mod_timer(&device_timer, jiffies + TIMEOUT_VALUE);    \
      } while (0)

static void (*do_hd)(void) = NULL;
#define SET_HANDLER(x) \
if ((do_hd = (x)) != NULL) \
      SET_TIMER; \
else \
      del_timer(&device_timer);


#if (HD_DELAY > 0)

#include <asm/i8253.h>

unsigned long last_req;

unsigned long read_timer(void)
{
      unsigned long t, flags;
      int i;

      spin_lock_irqsave(&i8253_lock, flags);
      t = jiffies * 11932;
      outb_p(0, 0x43);
      i = inb_p(0x40);
      i |= inb(0x40) << 8;
      spin_unlock_irqrestore(&i8253_lock, flags);
      return(t - i);
}
#endif

static void __init hd_setup(char *str, int *ints)
{
      int hdind = 0;

      if (ints[0] != 3)
            return;
      if (hd_info[0].head != 0)
            hdind=1;
      hd_info[hdind].head = ints[2];
      hd_info[hdind].sect = ints[3];
      hd_info[hdind].cyl = ints[1];
      hd_info[hdind].wpcom = 0;
      hd_info[hdind].lzone = ints[1];
      hd_info[hdind].ctl = (ints[2] > 8 ? 8 : 0);
      NR_HD = hdind+1;
}

static void dump_status (const char *msg, unsigned int stat)
{
      char *name = "hd?";
      if (CURRENT)
            name = CURRENT->rq_disk->disk_name;

#ifdef VERBOSE_ERRORS
      printk("%s: %s: status=0x%02x { ", name, msg, stat & 0xff);
      if (stat & BUSY_STAT)   printk("Busy ");
      if (stat & READY_STAT)  printk("DriveReady ");
      if (stat & WRERR_STAT)  printk("WriteFault ");
      if (stat & SEEK_STAT)   printk("SeekComplete ");
      if (stat & DRQ_STAT)    printk("DataRequest ");
      if (stat & ECC_STAT)    printk("CorrectedError ");
      if (stat & INDEX_STAT)  printk("Index ");
      if (stat & ERR_STAT)    printk("Error ");
      printk("}\n");
      if ((stat & ERR_STAT) == 0) {
            hd_error = 0;
      } else {
            hd_error = inb(HD_ERROR);
            printk("%s: %s: error=0x%02x { ", name, msg, hd_error & 0xff);
            if (hd_error & BBD_ERR)       printk("BadSector ");
            if (hd_error & ECC_ERR)       printk("UncorrectableError ");
            if (hd_error & ID_ERR)        printk("SectorIdNotFound ");
            if (hd_error & ABRT_ERR)      printk("DriveStatusError ");
            if (hd_error & TRK0_ERR)      printk("TrackZeroNotFound ");
            if (hd_error & MARK_ERR)      printk("AddrMarkNotFound ");
            printk("}");
            if (hd_error & (BBD_ERR|ECC_ERR|ID_ERR|MARK_ERR)) {
                  printk(", CHS=%d/%d/%d", (inb(HD_HCYL)<<8) + inb(HD_LCYL),
                        inb(HD_CURRENT) & 0xf, inb(HD_SECTOR));
                  if (CURRENT)
                        printk(", sector=%ld", CURRENT->sector);
            }
            printk("\n");
      }
#else
      printk("%s: %s: status=0x%02x.\n", name, msg, stat & 0xff);
      if ((stat & ERR_STAT) == 0) {
            hd_error = 0;
      } else {
            hd_error = inb(HD_ERROR);
            printk("%s: %s: error=0x%02x.\n", name, msg, hd_error & 0xff);
      }
#endif
}

static void check_status(void)
{
      int i = inb_p(HD_STATUS);

      if (!OK_STATUS(i)) {
            dump_status("check_status", i);
            bad_rw_intr();
      }
}

static int controller_busy(void)
{
      int retries = 100000;
      unsigned char status;

      do {
            status = inb_p(HD_STATUS);
      } while ((status & BUSY_STAT) && --retries);
      return status;
}

static int status_ok(void)
{
      unsigned char status = inb_p(HD_STATUS);

      if (status & BUSY_STAT)
            return 1;   /* Ancient, but does it make sense??? */
      if (status & WRERR_STAT)
            return 0;
      if (!(status & READY_STAT))
            return 0;
      if (!(status & SEEK_STAT))
            return 0;
      return 1;
}

static int controller_ready(unsigned int drive, unsigned int head)
{
      int retry = 100;

      do {
            if (controller_busy() & BUSY_STAT)
                  return 0;
            outb_p(0xA0 | (drive<<4) | head, HD_CURRENT);
            if (status_ok())
                  return 1;
      } while (--retry);
      return 0;
}

            
static void hd_out(struct hd_i_struct *disk,
               unsigned int nsect,
               unsigned int sect,
               unsigned int head,
               unsigned int cyl,
               unsigned int cmd,
               void (*intr_addr)(void))
{
      unsigned short port;

#if (HD_DELAY > 0)
      while (read_timer() - last_req < HD_DELAY)
            /* nothing */;
#endif
      if (reset)
            return;
      if (!controller_ready(disk->unit, head)) {
            reset = 1;
            return;
      }
      SET_HANDLER(intr_addr);
      outb_p(disk->ctl,HD_CMD);
      port=HD_DATA;
      outb_p(disk->wpcom>>2,++port);
      outb_p(nsect,++port);
      outb_p(sect,++port);
      outb_p(cyl,++port);
      outb_p(cyl>>8,++port);
      outb_p(0xA0|(disk->unit<<4)|head,++port);
      outb_p(cmd,++port);
}

static void hd_request (void);

static int drive_busy(void)
{
      unsigned int i;
      unsigned char c;

      for (i = 0; i < 500000 ; i++) {
            c = inb_p(HD_STATUS);
            if ((c & (BUSY_STAT | READY_STAT | SEEK_STAT)) == STAT_OK)
                  return 0;
      }
      dump_status("reset timed out", c);
      return 1;
}

static void reset_controller(void)
{
      int   i;

      outb_p(4,HD_CMD);
      for(i = 0; i < 1000; i++) barrier();
      outb_p(hd_info[0].ctl & 0x0f,HD_CMD);
      for(i = 0; i < 1000; i++) barrier();
      if (drive_busy())
            printk("hd: controller still busy\n");
      else if ((hd_error = inb(HD_ERROR)) != 1)
            printk("hd: controller reset failed: %02x\n",hd_error);
}

static void reset_hd(void)
{
      static int i;

repeat:
      if (reset) {
            reset = 0;
            i = -1;
            reset_controller();
      } else {
            check_status();
            if (reset)
                  goto repeat;
      }
      if (++i < NR_HD) {
            struct hd_i_struct *disk = &hd_info[i];
            disk->special_op = disk->recalibrate = 1;
            hd_out(disk,disk->sect,disk->sect,disk->head-1,
                  disk->cyl,WIN_SPECIFY,&reset_hd);
            if (reset)
                  goto repeat;
      } else
            hd_request();
}

/*
 * Ok, don't know what to do with the unexpected interrupts: on some machines
 * doing a reset and a retry seems to result in an eternal loop. Right now I
 * ignore it, and just set the timeout.
 *
 * On laptops (and "green" PCs), an unexpected interrupt occurs whenever the
 * drive enters "idle", "standby", or "sleep" mode, so if the status looks
 * "good", we just ignore the interrupt completely.
 */
static void unexpected_hd_interrupt(void)
{
      unsigned int stat = inb_p(HD_STATUS);

      if (stat & (BUSY_STAT|DRQ_STAT|ECC_STAT|ERR_STAT)) {
            dump_status ("unexpected interrupt", stat);
            SET_TIMER;
      }
}

/*
 * bad_rw_intr() now tries to be a bit smarter and does things
 * according to the error returned by the controller.
 * -Mika Liljeberg (liljeber@cs.Helsinki.FI)
 */
static void bad_rw_intr(void)
{
      struct request *req = CURRENT;
      if (req != NULL) {
            struct hd_i_struct *disk = req->rq_disk->private_data;
            if (++req->errors >= MAX_ERRORS || (hd_error & BBD_ERR)) {
                  end_request(req, 0);
                  disk->special_op = disk->recalibrate = 1;
            } else if (req->errors % RESET_FREQ == 0)
                  reset = 1;
            else if ((hd_error & TRK0_ERR) || req->errors % RECAL_FREQ == 0)
                  disk->special_op = disk->recalibrate = 1;
            /* Otherwise just retry */
      }
}

static inline int wait_DRQ(void)
{
      int retries = 100000, stat;

      while (--retries > 0)
            if ((stat = inb_p(HD_STATUS)) & DRQ_STAT)
                  return 0;
      dump_status("wait_DRQ", stat);
      return -1;
}

static void read_intr(void)
{
      struct request *req;
      int i, retries = 100000;

      do {
            i = (unsigned) inb_p(HD_STATUS);
            if (i & BUSY_STAT)
                  continue;
            if (!OK_STATUS(i))
                  break;
            if (i & DRQ_STAT)
                  goto ok_to_read;
      } while (--retries > 0);
      dump_status("read_intr", i);
      bad_rw_intr();
      hd_request();
      return;
ok_to_read:
      req = CURRENT;
      insw(HD_DATA,req->buffer,256);
      req->sector++;
      req->buffer += 512;
      req->errors = 0;
      i = --req->nr_sectors;
      --req->current_nr_sectors;
#ifdef DEBUG
      printk("%s: read: sector %ld, remaining = %ld, buffer=%p\n",
            req->rq_disk->disk_name, req->sector, req->nr_sectors,
            req->buffer+512);
#endif
      if (req->current_nr_sectors <= 0)
            end_request(req, 1);
      if (i > 0) {
            SET_HANDLER(&read_intr);
            return;
      }
      (void) inb_p(HD_STATUS);
#if (HD_DELAY > 0)
      last_req = read_timer();
#endif
      if (elv_next_request(QUEUE))
            hd_request();
      return;
}

static void write_intr(void)
{
      struct request *req = CURRENT;
      int i;
      int retries = 100000;

      do {
            i = (unsigned) inb_p(HD_STATUS);
            if (i & BUSY_STAT)
                  continue;
            if (!OK_STATUS(i))
                  break;
            if ((req->nr_sectors <= 1) || (i & DRQ_STAT))
                  goto ok_to_write;
      } while (--retries > 0);
      dump_status("write_intr", i);
      bad_rw_intr();
      hd_request();
      return;
ok_to_write:
      req->sector++;
      i = --req->nr_sectors;
      --req->current_nr_sectors;
      req->buffer += 512;
      if (!i || (req->bio && req->current_nr_sectors <= 0))
            end_request(req, 1);
      if (i > 0) {
            SET_HANDLER(&write_intr);
            outsw(HD_DATA,req->buffer,256);
            local_irq_enable();
      } else {
#if (HD_DELAY > 0)
            last_req = read_timer();
#endif
            hd_request();
      }
      return;
}

static void recal_intr(void)
{
      check_status();
#if (HD_DELAY > 0)
      last_req = read_timer();
#endif
      hd_request();
}

/*
 * This is another of the error-routines I don't know what to do with. The
 * best idea seems to just set reset, and start all over again.
 */
static void hd_times_out(unsigned long dummy)
{
      char *name;

      do_hd = NULL;

      if (!CURRENT)
            return;

      disable_irq(HD_IRQ);
      local_irq_enable();
      reset = 1;
      name = CURRENT->rq_disk->disk_name;
      printk("%s: timeout\n", name);
      if (++CURRENT->errors >= MAX_ERRORS) {
#ifdef DEBUG
            printk("%s: too many errors\n", name);
#endif
            end_request(CURRENT, 0);
      }
      local_irq_disable();
      hd_request();
      enable_irq(HD_IRQ);
}

static int do_special_op(struct hd_i_struct *disk, struct request *req)
{
      if (disk->recalibrate) {
            disk->recalibrate = 0;
            hd_out(disk,disk->sect,0,0,0,WIN_RESTORE,&recal_intr);
            return reset;
      }
      if (disk->head > 16) {
            printk ("%s: cannot handle device with more than 16 heads - giving up\n", req->rq_disk->disk_name);
            end_request(req, 0);
      }
      disk->special_op = 0;
      return 1;
}

/*
 * The driver enables interrupts as much as possible.  In order to do this,
 * (a) the device-interrupt is disabled before entering hd_request(),
 * and (b) the timeout-interrupt is disabled before the sti().
 *
 * Interrupts are still masked (by default) whenever we are exchanging
 * data/cmds with a drive, because some drives seem to have very poor
 * tolerance for latency during I/O. The IDE driver has support to unmask
 * interrupts for non-broken hardware, so use that driver if required.
 */
static void hd_request(void)
{
      unsigned int block, nsect, sec, track, head, cyl;
      struct hd_i_struct *disk;
      struct request *req;

      if (do_hd)
            return;
repeat:
      del_timer(&device_timer);
      local_irq_enable();

      req = CURRENT;
      if (!req) {
            do_hd = NULL;
            return;
      }

      if (reset) {
            local_irq_disable();
            reset_hd();
            return;
      }
      disk = req->rq_disk->private_data;
      block = req->sector;
      nsect = req->nr_sectors;
      if (block >= get_capacity(req->rq_disk) ||
          ((block+nsect) > get_capacity(req->rq_disk))) {
            printk("%s: bad access: block=%d, count=%d\n",
                  req->rq_disk->disk_name, block, nsect);
            end_request(req, 0);
            goto repeat;
      }

      if (disk->special_op) {
            if (do_special_op(disk, req))
                  goto repeat;
            return;
      }
      sec   = block % disk->sect + 1;
      track = block / disk->sect;
      head  = track % disk->head;
      cyl   = track / disk->head;
#ifdef DEBUG
      printk("%s: %sing: CHS=%d/%d/%d, sectors=%d, buffer=%p\n",
            req->rq_disk->disk_name,
            req_data_dir(req) == READ ? "read" : "writ",
            cyl, head, sec, nsect, req->buffer);
#endif
      if (blk_fs_request(req)) {
            switch (rq_data_dir(req)) {
            case READ:
                  hd_out(disk,nsect,sec,head,cyl,WIN_READ,&read_intr);
                  if (reset)
                        goto repeat;
                  break;
            case WRITE:
                  hd_out(disk,nsect,sec,head,cyl,WIN_WRITE,&write_intr);
                  if (reset)
                        goto repeat;
                  if (wait_DRQ()) {
                        bad_rw_intr();
                        goto repeat;
                  }
                  outsw(HD_DATA,req->buffer,256);
                  break;
            default:
                  printk("unknown hd-command\n");
                  end_request(req, 0);
                  break;
            }
      }
}

static void do_hd_request (struct request_queue * q)
{
      disable_irq(HD_IRQ);
      hd_request();
      enable_irq(HD_IRQ);
}

static int hd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
      struct hd_i_struct *disk = bdev->bd_disk->private_data;

      geo->heads = disk->head;
      geo->sectors = disk->sect;
      geo->cylinders = disk->cyl;
      return 0;
}

/*
 * Releasing a block device means we sync() it, so that it can safely
 * be forgotten about...
 */

static irqreturn_t hd_interrupt(int irq, void *dev_id)
{
      void (*handler)(void) = do_hd;

      do_hd = NULL;
      del_timer(&device_timer);
      if (!handler)
            handler = unexpected_hd_interrupt;
      handler();
      local_irq_enable();
      return IRQ_HANDLED;
}

static struct block_device_operations hd_fops = {
      .getgeo =   hd_getgeo,
};

/*
 * This is the hard disk IRQ description. The IRQF_DISABLED in sa_flags
 * means we run the IRQ-handler with interrupts disabled:  this is bad for
 * interrupt latency, but anything else has led to problems on some
 * machines.
 *
 * We enable interrupts in some of the routines after making sure it's
 * safe.
 */

static int __init hd_init(void)
{
      int drive;

      if (register_blkdev(MAJOR_NR,"hd"))
            return -1;

      hd_queue = blk_init_queue(do_hd_request, &hd_lock);
      if (!hd_queue) {
            unregister_blkdev(MAJOR_NR,"hd");
            return -ENOMEM;
      }

      blk_queue_max_sectors(hd_queue, 255);
      init_timer(&device_timer);
      device_timer.function = hd_times_out;
      blk_queue_hardsect_size(hd_queue, 512);

      if (!NR_HD) {
            /*
             * We don't know anything about the drive.  This means
             * that you *MUST* specify the drive parameters to the
             * kernel yourself.
             *
             * If we were on an i386, we used to read this info from
             * the BIOS or CMOS.  This doesn't work all that well,
             * since this assumes that this is a primary or secondary
             * drive, and if we're using this legacy driver, it's
             * probably an auxilliary controller added to recover
             * legacy data off an ST-506 drive.  Either way, it's
             * definitely safest to have the user explicitly specify
             * the information.
             */
            printk("hd: no drives specified - use hd=cyl,head,sectors"
                  " on kernel command line\n");
            goto out;
      }

      for (drive=0 ; drive < NR_HD ; drive++) {
            struct gendisk *disk = alloc_disk(64);
            struct hd_i_struct *p = &hd_info[drive];
            if (!disk)
                  goto Enomem;
            disk->major = MAJOR_NR;
            disk->first_minor = drive << 6;
            disk->fops = &hd_fops;
            sprintf(disk->disk_name, "hd%c", 'a'+drive);
            disk->private_data = p;
            set_capacity(disk, p->head * p->sect * p->cyl);
            disk->queue = hd_queue;
            p->unit = drive;
            hd_gendisk[drive] = disk;
            printk ("%s: %luMB, CHS=%d/%d/%d\n",
                  disk->disk_name, (unsigned long)get_capacity(disk)/2048,
                  p->cyl, p->head, p->sect);
      }

      if (request_irq(HD_IRQ, hd_interrupt, IRQF_DISABLED, "hd", NULL)) {
            printk("hd: unable to get IRQ%d for the hard disk driver\n",
                  HD_IRQ);
            goto out1;
      }
      if (!request_region(HD_DATA, 8, "hd")) {
            printk(KERN_WARNING "hd: port 0x%x busy\n", HD_DATA);
            goto out2;
      }
      if (!request_region(HD_CMD, 1, "hd(cmd)")) {
            printk(KERN_WARNING "hd: port 0x%x busy\n", HD_CMD);
            goto out3;
      }

      /* Let them fly */
      for(drive=0; drive < NR_HD; drive++)
            add_disk(hd_gendisk[drive]);

      return 0;

out3:
      release_region(HD_DATA, 8);
out2:
      free_irq(HD_IRQ, NULL);
out1:
      for (drive = 0; drive < NR_HD; drive++)
            put_disk(hd_gendisk[drive]);
      NR_HD = 0;
out:
      del_timer(&device_timer);
      unregister_blkdev(MAJOR_NR,"hd");
      blk_cleanup_queue(hd_queue);
      return -1;
Enomem:
      while (drive--)
            put_disk(hd_gendisk[drive]);
      goto out;
}

static int __init parse_hd_setup (char *line) {
      int ints[6];

      (void) get_options(line, ARRAY_SIZE(ints), ints);
      hd_setup(NULL, ints);

      return 1;
}
__setup("hd=", parse_hd_setup);

module_init(hd_init);

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