/*
 *  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/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;
        int stat;

        for (retries = 0; retries < 100000; retries++) {
                stat = inb_p(HD_STATUS);
                if (stat & 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);

late_initcall(hd_init);