Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 864 insertions, 0 deletions

diff --git a/drivers/ide/legacy/hd.c b/drivers/ide/legacy/hd.c
new file mode 100644
index 000000000000..c4090550ec13
--- /dev/null
+++ b/drivers/ide/legacy/hd.c
@@ -0,0 +1,864 @@
+/*
+ *  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 = ((sizeof (hd_info))/(sizeof (struct hd_i_struct)));
+#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)
+unsigned long last_req;
+
+unsigned long read_timer(void)
+{
+        extern spinlock_t i8253_lock;
+        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->cmd == READ)?"read":"writ",
+                cyl, head, sec, nsect, req->buffer);
+#endif
+        if (req->flags & REQ_CMD) {
+                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 (request_queue_t * q)
+{
+        disable_irq(HD_IRQ);
+        hd_request();
+        enable_irq(HD_IRQ);
+}
+
+static int hd_ioctl(struct inode * inode, struct file * file,
+        unsigned int cmd, unsigned long arg)
+{
+        struct hd_i_struct *disk = inode->i_bdev->bd_disk->private_data;
+        struct hd_geometry __user *loc = (struct hd_geometry __user *) arg;
+        struct hd_geometry g; 
+
+        if (cmd != HDIO_GETGEO)
+                return -EINVAL;
+        if (!loc)
+                return -EINVAL;
+        g.heads = disk->head;
+        g.sectors = disk->sect;
+        g.cylinders = disk->cyl;
+        g.start = get_start_sect(inode->i_bdev);
+        return copy_to_user(loc, &g, sizeof g) ? -EFAULT : 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, struct pt_regs *regs)
+{
+        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 = {
+        .ioctl =        hd_ioctl,
+};
+
+/*
+ * This is the hard disk IRQ description. The SA_INTERRUPT 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);
+
+#ifdef __i386__
+        if (!NR_HD) {
+                extern struct drive_info drive_info;
+                unsigned char *BIOS = (unsigned char *) &drive_info;
+                unsigned long flags;
+                int cmos_disks;
+
+                for (drive=0 ; drive<2 ; drive++) {
+                        hd_info[drive].cyl = *(unsigned short *) BIOS;
+                        hd_info[drive].head = *(2+BIOS);
+                        hd_info[drive].wpcom = *(unsigned short *) (5+BIOS);
+                        hd_info[drive].ctl = *(8+BIOS);
+                        hd_info[drive].lzone = *(unsigned short *) (12+BIOS);
+                        hd_info[drive].sect = *(14+BIOS);
+#ifdef does_not_work_for_everybody_with_scsi_but_helps_ibm_vp
+                        if (hd_info[drive].cyl && NR_HD == drive)
+                                NR_HD++;
+#endif
+                        BIOS += 16;
+                }
+
+        /*
+                We query CMOS about hard disks : it could be that 
+                we have a SCSI/ESDI/etc controller that is BIOS
+                compatible with ST-506, and thus showing up in our
+                BIOS table, but not register compatible, and therefore
+                not present in CMOS.
+
+                Furthermore, we will assume that our ST-506 drives
+                <if any> are the primary drives in the system, and 
+                the ones reflected as drive 1 or 2.
+
+                The first drive is stored in the high nibble of CMOS
+                byte 0x12, the second in the low nibble.  This will be
+                either a 4 bit drive type or 0xf indicating use byte 0x19 
+                for an 8 bit type, drive 1, 0x1a for drive 2 in CMOS.
+
+                Needless to say, a non-zero value means we have 
+                an AT controller hard disk for that drive.
+
+                Currently the rtc_lock is a bit academic since this
+                driver is non-modular, but someday... ?         Paul G.
+        */
+
+                spin_lock_irqsave(&rtc_lock, flags);
+                cmos_disks = CMOS_READ(0x12);
+                spin_unlock_irqrestore(&rtc_lock, flags);
+
+                if (cmos_disks & 0xf0) {
+                        if (cmos_disks & 0x0f)
+                                NR_HD = 2;
+                        else
+                                NR_HD = 1;
+                }
+        }
+#endif /* __i386__ */
+#ifdef __arm__
+        if (!NR_HD) {
+                /* We don't know anything about the drive.  This means
+                 * that you *MUST* specify the drive parameters to the
+                 * kernel yourself.
+                 */
+                printk("hd: no drives specified - use hd=cyl,head,sectors"
+                        " on kernel command line\n");
+        }
+#endif
+        if (!NR_HD)
+                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, SA_INTERRUPT, "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 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);