[PATCH] libata: Remove dependence on host_set->dev for SAS

[linux-2.6.git] / drivers / scsi / libata-core.c

/*
 *  libata-core.c - helper library for ATA
 *
 *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
 *                  Please ALWAYS copy linux-ide@vger.kernel.org
 *                  on emails.
 *
 *  Copyright 2003-2004 Red Hat, Inc.  All rights reserved.
 *  Copyright 2003-2004 Jeff Garzik
 *
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 *  Hardware documentation available from http://www.t13.org/ and
 *  http://www.sata-io.org/
 *
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/suspend.h>
#include <linux/workqueue.h>
#include <linux/jiffies.h>
#include <linux/scatterlist.h>
#include <scsi/scsi.h>
#include "scsi_priv.h"
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <linux/libata.h>
#include <asm/io.h>
#include <asm/semaphore.h>
#include <asm/byteorder.h>

#include "libata.h"

static unsigned int ata_dev_init_params(struct ata_port *ap,
                                        struct ata_device *dev);
static void ata_set_mode(struct ata_port *ap);
static unsigned int ata_dev_set_xfermode(struct ata_port *ap,
                                         struct ata_device *dev);
static void ata_dev_xfermask(struct ata_port *ap, struct ata_device *dev);

static unsigned int ata_unique_id = 1;
static struct workqueue_struct *ata_wq;

int atapi_enabled = 1;
module_param(atapi_enabled, int, 0444);
MODULE_PARM_DESC(atapi_enabled, "Enable discovery of ATAPI devices (0=off, 1=on)");

int libata_fua = 0;
module_param_named(fua, libata_fua, int, 0444);
MODULE_PARM_DESC(fua, "FUA support (0=off, 1=on)");

MODULE_AUTHOR("Jeff Garzik");
MODULE_DESCRIPTION("Library module for ATA devices");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);


/**
 *      ata_tf_to_fis - Convert ATA taskfile to SATA FIS structure
 *      @tf: Taskfile to convert
 *      @fis: Buffer into which data will output
 *      @pmp: Port multiplier port
 *
 *      Converts a standard ATA taskfile to a Serial ATA
 *      FIS structure (Register - Host to Device).
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_tf_to_fis(const struct ata_taskfile *tf, u8 *fis, u8 pmp)
{
        fis[0] = 0x27;  /* Register - Host to Device FIS */
        fis[1] = (pmp & 0xf) | (1 << 7); /* Port multiplier number,
                                            bit 7 indicates Command FIS */
        fis[2] = tf->command;
        fis[3] = tf->feature;

        fis[4] = tf->lbal;
        fis[5] = tf->lbam;
        fis[6] = tf->lbah;
        fis[7] = tf->device;

        fis[8] = tf->hob_lbal;
        fis[9] = tf->hob_lbam;
        fis[10] = tf->hob_lbah;
        fis[11] = tf->hob_feature;

        fis[12] = tf->nsect;
        fis[13] = tf->hob_nsect;
        fis[14] = 0;
        fis[15] = tf->ctl;

        fis[16] = 0;
        fis[17] = 0;
        fis[18] = 0;
        fis[19] = 0;
}

/**
 *      ata_tf_from_fis - Convert SATA FIS to ATA taskfile
 *      @fis: Buffer from which data will be input
 *      @tf: Taskfile to output
 *
 *      Converts a serial ATA FIS structure to a standard ATA taskfile.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_tf_from_fis(const u8 *fis, struct ata_taskfile *tf)
{
        tf->command     = fis[2];       /* status */
        tf->feature     = fis[3];       /* error */

        tf->lbal        = fis[4];
        tf->lbam        = fis[5];
        tf->lbah        = fis[6];
        tf->device      = fis[7];

        tf->hob_lbal    = fis[8];
        tf->hob_lbam    = fis[9];
        tf->hob_lbah    = fis[10];

        tf->nsect       = fis[12];
        tf->hob_nsect   = fis[13];
}

static const u8 ata_rw_cmds[] = {
        /* pio multi */
        ATA_CMD_READ_MULTI,
        ATA_CMD_WRITE_MULTI,
        ATA_CMD_READ_MULTI_EXT,
        ATA_CMD_WRITE_MULTI_EXT,
        0,
        0,
        0,
        ATA_CMD_WRITE_MULTI_FUA_EXT,
        /* pio */
        ATA_CMD_PIO_READ,
        ATA_CMD_PIO_WRITE,
        ATA_CMD_PIO_READ_EXT,
        ATA_CMD_PIO_WRITE_EXT,
        0,
        0,
        0,
        0,
        /* dma */
        ATA_CMD_READ,
        ATA_CMD_WRITE,
        ATA_CMD_READ_EXT,
        ATA_CMD_WRITE_EXT,
        0,
        0,
        0,
        ATA_CMD_WRITE_FUA_EXT
};

/**
 *      ata_rwcmd_protocol - set taskfile r/w commands and protocol
 *      @qc: command to examine and configure
 *
 *      Examine the device configuration and tf->flags to calculate
 *      the proper read/write commands and protocol to use.
 *
 *      LOCKING:
 *      caller.
 */
int ata_rwcmd_protocol(struct ata_queued_cmd *qc)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        u8 cmd;

        int index, fua, lba48, write;

        fua = (tf->flags & ATA_TFLAG_FUA) ? 4 : 0;
        lba48 = (tf->flags & ATA_TFLAG_LBA48) ? 2 : 0;
        write = (tf->flags & ATA_TFLAG_WRITE) ? 1 : 0;

        if (dev->flags & ATA_DFLAG_PIO) {
                tf->protocol = ATA_PROT_PIO;
                index = dev->multi_count ? 0 : 8;
        } else if (lba48 && (qc->ap->flags & ATA_FLAG_PIO_LBA48)) {
                /* Unable to use DMA due to host limitation */
                tf->protocol = ATA_PROT_PIO;
                index = dev->multi_count ? 0 : 8;
        } else {
                tf->protocol = ATA_PROT_DMA;
                index = 16;
        }

        cmd = ata_rw_cmds[index + fua + lba48 + write];
        if (cmd) {
                tf->command = cmd;
                return 0;
        }
        return -1;
}

/**
 *      ata_pack_xfermask - Pack pio, mwdma and udma masks into xfer_mask
 *      @pio_mask: pio_mask
 *      @mwdma_mask: mwdma_mask
 *      @udma_mask: udma_mask
 *
 *      Pack @pio_mask, @mwdma_mask and @udma_mask into a single
 *      unsigned int xfer_mask.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Packed xfer_mask.
 */
static unsigned int ata_pack_xfermask(unsigned int pio_mask,
                                      unsigned int mwdma_mask,
                                      unsigned int udma_mask)
{
        return ((pio_mask << ATA_SHIFT_PIO) & ATA_MASK_PIO) |
                ((mwdma_mask << ATA_SHIFT_MWDMA) & ATA_MASK_MWDMA) |
                ((udma_mask << ATA_SHIFT_UDMA) & ATA_MASK_UDMA);
}

/**
 *      ata_unpack_xfermask - Unpack xfer_mask into pio, mwdma and udma masks
 *      @xfer_mask: xfer_mask to unpack
 *      @pio_mask: resulting pio_mask
 *      @mwdma_mask: resulting mwdma_mask
 *      @udma_mask: resulting udma_mask
 *
 *      Unpack @xfer_mask into @pio_mask, @mwdma_mask and @udma_mask.
 *      Any NULL distination masks will be ignored.
 */
static void ata_unpack_xfermask(unsigned int xfer_mask,
                                unsigned int *pio_mask,
                                unsigned int *mwdma_mask,
                                unsigned int *udma_mask)
{
        if (pio_mask)
                *pio_mask = (xfer_mask & ATA_MASK_PIO) >> ATA_SHIFT_PIO;
        if (mwdma_mask)
                *mwdma_mask = (xfer_mask & ATA_MASK_MWDMA) >> ATA_SHIFT_MWDMA;
        if (udma_mask)
                *udma_mask = (xfer_mask & ATA_MASK_UDMA) >> ATA_SHIFT_UDMA;
}

static const struct ata_xfer_ent {
        unsigned int shift, bits;
        u8 base;
} ata_xfer_tbl[] = {
        { ATA_SHIFT_PIO, ATA_BITS_PIO, XFER_PIO_0 },
        { ATA_SHIFT_MWDMA, ATA_BITS_MWDMA, XFER_MW_DMA_0 },
        { ATA_SHIFT_UDMA, ATA_BITS_UDMA, XFER_UDMA_0 },
        { -1, },
};

/**
 *      ata_xfer_mask2mode - Find matching XFER_* for the given xfer_mask
 *      @xfer_mask: xfer_mask of interest
 *
 *      Return matching XFER_* value for @xfer_mask.  Only the highest
 *      bit of @xfer_mask is considered.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching XFER_* value, 0 if no match found.
 */
static u8 ata_xfer_mask2mode(unsigned int xfer_mask)
{
        int highbit = fls(xfer_mask) - 1;
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (highbit >= ent->shift && highbit < ent->shift + ent->bits)
                        return ent->base + highbit - ent->shift;
        return 0;
}

/**
 *      ata_xfer_mode2mask - Find matching xfer_mask for XFER_*
 *      @xfer_mode: XFER_* of interest
 *
 *      Return matching xfer_mask for @xfer_mode.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching xfer_mask, 0 if no match found.
 */
static unsigned int ata_xfer_mode2mask(u8 xfer_mode)
{
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
                        return 1 << (ent->shift + xfer_mode - ent->base);
        return 0;
}

/**
 *      ata_xfer_mode2shift - Find matching xfer_shift for XFER_*
 *      @xfer_mode: XFER_* of interest
 *
 *      Return matching xfer_shift for @xfer_mode.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching xfer_shift, -1 if no match found.
 */
static int ata_xfer_mode2shift(unsigned int xfer_mode)
{
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
                        return ent->shift;
        return -1;
}

/**
 *      ata_mode_string - convert xfer_mask to string
 *      @xfer_mask: mask of bits supported; only highest bit counts.
 *
 *      Determine string which represents the highest speed
 *      (highest bit in @modemask).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Constant C string representing highest speed listed in
 *      @mode_mask, or the constant C string "<n/a>".
 */
static const char *ata_mode_string(unsigned int xfer_mask)
{
        static const char * const xfer_mode_str[] = {
                "PIO0",
                "PIO1",
                "PIO2",
                "PIO3",
                "PIO4",
                "MWDMA0",
                "MWDMA1",
                "MWDMA2",
                "UDMA/16",
                "UDMA/25",
                "UDMA/33",
                "UDMA/44",
                "UDMA/66",
                "UDMA/100",
                "UDMA/133",
                "UDMA7",
        };
        int highbit;

        highbit = fls(xfer_mask) - 1;
        if (highbit >= 0 && highbit < ARRAY_SIZE(xfer_mode_str))
                return xfer_mode_str[highbit];
        return "<n/a>";
}

static void ata_dev_disable(struct ata_port *ap, struct ata_device *dev)
{
        if (ata_dev_present(dev)) {
                printk(KERN_WARNING "ata%u: dev %u disabled\n",
                       ap->id, dev->devno);
                dev->class++;
        }
}

/**
 *      ata_pio_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      This technique was originally described in
 *      Hale Landis's ATADRVR (www.ata-atapi.com), and
 *      later found its way into the ATA/ATAPI spec.
 *
 *      Write a pattern to the ATA shadow registers,
 *      and if a device is present, it will respond by
 *      correctly storing and echoing back the
 *      ATA shadow register contents.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_pio_devchk(struct ata_port *ap,
                                   unsigned int device)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 nsect, lbal;

        ap->ops->dev_select(ap, device);

        outb(0x55, ioaddr->nsect_addr);
        outb(0xaa, ioaddr->lbal_addr);

        outb(0xaa, ioaddr->nsect_addr);
        outb(0x55, ioaddr->lbal_addr);

        outb(0x55, ioaddr->nsect_addr);
        outb(0xaa, ioaddr->lbal_addr);

        nsect = inb(ioaddr->nsect_addr);
        lbal = inb(ioaddr->lbal_addr);

        if ((nsect == 0x55) && (lbal == 0xaa))
                return 1;       /* we found a device */

        return 0;               /* nothing found */
}

/**
 *      ata_mmio_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      This technique was originally described in
 *      Hale Landis's ATADRVR (www.ata-atapi.com), and
 *      later found its way into the ATA/ATAPI spec.
 *
 *      Write a pattern to the ATA shadow registers,
 *      and if a device is present, it will respond by
 *      correctly storing and echoing back the
 *      ATA shadow register contents.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_mmio_devchk(struct ata_port *ap,
                                    unsigned int device)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 nsect, lbal;

        ap->ops->dev_select(ap, device);

        writeb(0x55, (void __iomem *) ioaddr->nsect_addr);
        writeb(0xaa, (void __iomem *) ioaddr->lbal_addr);

        writeb(0xaa, (void __iomem *) ioaddr->nsect_addr);
        writeb(0x55, (void __iomem *) ioaddr->lbal_addr);

        writeb(0x55, (void __iomem *) ioaddr->nsect_addr);
        writeb(0xaa, (void __iomem *) ioaddr->lbal_addr);

        nsect = readb((void __iomem *) ioaddr->nsect_addr);
        lbal = readb((void __iomem *) ioaddr->lbal_addr);

        if ((nsect == 0x55) && (lbal == 0xaa))
                return 1;       /* we found a device */

        return 0;               /* nothing found */
}

/**
 *      ata_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      Dispatch ATA device presence detection, depending
 *      on whether we are using PIO or MMIO to talk to the
 *      ATA shadow registers.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_devchk(struct ata_port *ap,
                                    unsigned int device)
{
        if (ap->flags & ATA_FLAG_MMIO)
                return ata_mmio_devchk(ap, device);
        return ata_pio_devchk(ap, device);
}

/**
 *      ata_dev_classify - determine device type based on ATA-spec signature
 *      @tf: ATA taskfile register set for device to be identified
 *
 *      Determine from taskfile register contents whether a device is
 *      ATA or ATAPI, as per "Signature and persistence" section
 *      of ATA/PI spec (volume 1, sect 5.14).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Device type, %ATA_DEV_ATA, %ATA_DEV_ATAPI, or %ATA_DEV_UNKNOWN
 *      the event of failure.
 */

unsigned int ata_dev_classify(const struct ata_taskfile *tf)
{
        /* Apple's open source Darwin code hints that some devices only
         * put a proper signature into the LBA mid/high registers,
         * So, we only check those.  It's sufficient for uniqueness.
         */

        if (((tf->lbam == 0) && (tf->lbah == 0)) ||
            ((tf->lbam == 0x3c) && (tf->lbah == 0xc3))) {
                DPRINTK("found ATA device by sig\n");
                return ATA_DEV_ATA;
        }

        if (((tf->lbam == 0x14) && (tf->lbah == 0xeb)) ||
            ((tf->lbam == 0x69) && (tf->lbah == 0x96))) {
                DPRINTK("found ATAPI device by sig\n");
                return ATA_DEV_ATAPI;
        }

        DPRINTK("unknown device\n");
        return ATA_DEV_UNKNOWN;
}

/**
 *      ata_dev_try_classify - Parse returned ATA device signature
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *      @r_err: Value of error register on completion
 *
 *      After an event -- SRST, E.D.D., or SATA COMRESET -- occurs,
 *      an ATA/ATAPI-defined set of values is placed in the ATA
 *      shadow registers, indicating the results of device detection
 *      and diagnostics.
 *
 *      Select the ATA device, and read the values from the ATA shadow
 *      registers.  Then parse according to the Error register value,
 *      and the spec-defined values examined by ata_dev_classify().
 *
 *      LOCKING:
 *      caller.
 *
 *      RETURNS:
 *      Device type - %ATA_DEV_ATA, %ATA_DEV_ATAPI or %ATA_DEV_NONE.
 */

static unsigned int
ata_dev_try_classify(struct ata_port *ap, unsigned int device, u8 *r_err)
{
        struct ata_taskfile tf;
        unsigned int class;
        u8 err;

        ap->ops->dev_select(ap, device);

        memset(&tf, 0, sizeof(tf));

        ap->ops->tf_read(ap, &tf);
        err = tf.feature;
        if (r_err)
                *r_err = err;

        /* see if device passed diags */
        if (err == 1)
                /* do nothing */ ;
        else if ((device == 0) && (err == 0x81))
                /* do nothing */ ;
        else
                return ATA_DEV_NONE;

        /* determine if device is ATA or ATAPI */
        class = ata_dev_classify(&tf);

        if (class == ATA_DEV_UNKNOWN)
                return ATA_DEV_NONE;
        if ((class == ATA_DEV_ATA) && (ata_chk_status(ap) == 0))
                return ATA_DEV_NONE;
        return class;
}

/**
 *      ata_id_string - Convert IDENTIFY DEVICE page into string
 *      @id: IDENTIFY DEVICE results we will examine
 *      @s: string into which data is output
 *      @ofs: offset into identify device page
 *      @len: length of string to return. must be an even number.
 *
 *      The strings in the IDENTIFY DEVICE page are broken up into
 *      16-bit chunks.  Run through the string, and output each
 *      8-bit chunk linearly, regardless of platform.
 *
 *      LOCKING:
 *      caller.
 */

void ata_id_string(const u16 *id, unsigned char *s,
                   unsigned int ofs, unsigned int len)
{
        unsigned int c;

        while (len > 0) {
                c = id[ofs] >> 8;
                *s = c;
                s++;

                c = id[ofs] & 0xff;
                *s = c;
                s++;

                ofs++;
                len -= 2;
        }
}

/**
 *      ata_id_c_string - Convert IDENTIFY DEVICE page into C string
 *      @id: IDENTIFY DEVICE results we will examine
 *      @s: string into which data is output
 *      @ofs: offset into identify device page
 *      @len: length of string to return. must be an odd number.
 *
 *      This function is identical to ata_id_string except that it
 *      trims trailing spaces and terminates the resulting string with
 *      null.  @len must be actual maximum length (even number) + 1.
 *
 *      LOCKING:
 *      caller.
 */
void ata_id_c_string(const u16 *id, unsigned char *s,
                     unsigned int ofs, unsigned int len)
{
        unsigned char *p;

        WARN_ON(!(len & 1));

        ata_id_string(id, s, ofs, len - 1);

        p = s + strnlen(s, len - 1);
        while (p > s && p[-1] == ' ')
                p--;
        *p = '\0';
}

static u64 ata_id_n_sectors(const u16 *id)
{
        if (ata_id_has_lba(id)) {
                if (ata_id_has_lba48(id))
                        return ata_id_u64(id, 100);
                else
                        return ata_id_u32(id, 60);
        } else {
                if (ata_id_current_chs_valid(id))
                        return ata_id_u32(id, 57);
                else
                        return id[1] * id[3] * id[6];
        }
}

/**
 *      ata_noop_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *
 *      This function performs no actual function.
 *
 *      May be used as the dev_select() entry in ata_port_operations.
 *
 *      LOCKING:
 *      caller.
 */
void ata_noop_dev_select (struct ata_port *ap, unsigned int device)
{
}


/**
 *      ata_std_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *
 *      Use the method defined in the ATA specification to
 *      make either device 0, or device 1, active on the
 *      ATA channel.  Works with both PIO and MMIO.
 *
 *      May be used as the dev_select() entry in ata_port_operations.
 *
 *      LOCKING:
 *      caller.
 */

void ata_std_dev_select (struct ata_port *ap, unsigned int device)
{
        u8 tmp;

        if (device == 0)
                tmp = ATA_DEVICE_OBS;
        else
                tmp = ATA_DEVICE_OBS | ATA_DEV1;

        if (ap->flags & ATA_FLAG_MMIO) {
                writeb(tmp, (void __iomem *) ap->ioaddr.device_addr);
        } else {
                outb(tmp, ap->ioaddr.device_addr);
        }
        ata_pause(ap);          /* needed; also flushes, for mmio */
}

/**
 *      ata_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *      @wait: non-zero to wait for Status register BSY bit to clear
 *      @can_sleep: non-zero if context allows sleeping
 *
 *      Use the method defined in the ATA specification to
 *      make either device 0, or device 1, active on the
 *      ATA channel.
 *
 *      This is a high-level version of ata_std_dev_select(),
 *      which additionally provides the services of inserting
 *      the proper pauses and status polling, where needed.
 *
 *      LOCKING:
 *      caller.
 */

void ata_dev_select(struct ata_port *ap, unsigned int device,
                           unsigned int wait, unsigned int can_sleep)
{
        VPRINTK("ENTER, ata%u: device %u, wait %u\n",
                ap->id, device, wait);

        if (wait)
                ata_wait_idle(ap);

        ap->ops->dev_select(ap, device);

        if (wait) {
                if (can_sleep && ap->device[device].class == ATA_DEV_ATAPI)
                        msleep(150);
                ata_wait_idle(ap);
        }
}

/**
 *      ata_dump_id - IDENTIFY DEVICE info debugging output
 *      @id: IDENTIFY DEVICE page to dump
 *
 *      Dump selected 16-bit words from the given IDENTIFY DEVICE
 *      page.
 *
 *      LOCKING:
 *      caller.
 */

static inline void ata_dump_id(const u16 *id)
{
        DPRINTK("49==0x%04x  "
                "53==0x%04x  "
                "63==0x%04x  "
                "64==0x%04x  "
                "75==0x%04x  \n",
                id[49],
                id[53],
                id[63],
                id[64],
                id[75]);
        DPRINTK("80==0x%04x  "
                "81==0x%04x  "
                "82==0x%04x  "
                "83==0x%04x  "
                "84==0x%04x  \n",
                id[80],
                id[81],
                id[82],
                id[83],
                id[84]);
        DPRINTK("88==0x%04x  "
                "93==0x%04x\n",
                id[88],
                id[93]);
}

/**
 *      ata_id_xfermask - Compute xfermask from the given IDENTIFY data
 *      @id: IDENTIFY data to compute xfer mask from
 *
 *      Compute the xfermask for this device. This is not as trivial
 *      as it seems if we must consider early devices correctly.
 *
 *      FIXME: pre IDE drive timing (do we care ?).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Computed xfermask
 */
static unsigned int ata_id_xfermask(const u16 *id)
{
        unsigned int pio_mask, mwdma_mask, udma_mask;

        /* Usual case. Word 53 indicates word 64 is valid */
        if (id[ATA_ID_FIELD_VALID] & (1 << 1)) {
                pio_mask = id[ATA_ID_PIO_MODES] & 0x03;
                pio_mask <<= 3;
                pio_mask |= 0x7;
        } else {
                /* If word 64 isn't valid then Word 51 high byte holds
                 * the PIO timing number for the maximum. Turn it into
                 * a mask.
                 */
                pio_mask = (2 << (id[ATA_ID_OLD_PIO_MODES] & 0xFF)) - 1 ;

                /* But wait.. there's more. Design your standards by
                 * committee and you too can get a free iordy field to
                 * process. However its the speeds not the modes that
                 * are supported... Note drivers using the timing API
                 * will get this right anyway
                 */
        }

        mwdma_mask = id[ATA_ID_MWDMA_MODES] & 0x07;

        udma_mask = 0;
        if (id[ATA_ID_FIELD_VALID] & (1 << 2))
                udma_mask = id[ATA_ID_UDMA_MODES] & 0xff;

        return ata_pack_xfermask(pio_mask, mwdma_mask, udma_mask);
}

/**
 *      ata_port_queue_task - Queue port_task
 *      @ap: The ata_port to queue port_task for
 *
 *      Schedule @fn(@data) for execution after @delay jiffies using
 *      port_task.  There is one port_task per port and it's the
 *      user(low level driver)'s responsibility to make sure that only
 *      one task is active at any given time.
 *
 *      libata core layer takes care of synchronization between
 *      port_task and EH.  ata_port_queue_task() may be ignored for EH
 *      synchronization.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_port_queue_task(struct ata_port *ap, void (*fn)(void *), void *data,
                         unsigned long delay)
{
        int rc;

        if (ap->flags & ATA_FLAG_FLUSH_PORT_TASK)
                return;

        PREPARE_WORK(&ap->port_task, fn, data);

        if (!delay)
                rc = queue_work(ata_wq, &ap->port_task);
        else
                rc = queue_delayed_work(ata_wq, &ap->port_task, delay);

        /* rc == 0 means that another user is using port task */
        WARN_ON(rc == 0);
}

/**
 *      ata_port_flush_task - Flush port_task
 *      @ap: The ata_port to flush port_task for
 *
 *      After this function completes, port_task is guranteed not to
 *      be running or scheduled.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_port_flush_task(struct ata_port *ap)
{
        unsigned long flags;

        DPRINTK("ENTER\n");

        spin_lock_irqsave(&ap->host_set->lock, flags);
        ap->flags |= ATA_FLAG_FLUSH_PORT_TASK;
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        DPRINTK("flush #1\n");
        flush_workqueue(ata_wq);

        /*
         * At this point, if a task is running, it's guaranteed to see
         * the FLUSH flag; thus, it will never queue pio tasks again.
         * Cancel and flush.
         */
        if (!cancel_delayed_work(&ap->port_task)) {
                DPRINTK("flush #2\n");
                flush_workqueue(ata_wq);
        }

        spin_lock_irqsave(&ap->host_set->lock, flags);
        ap->flags &= ~ATA_FLAG_FLUSH_PORT_TASK;
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        DPRINTK("EXIT\n");
}

void ata_qc_complete_internal(struct ata_queued_cmd *qc)
{
        struct completion *waiting = qc->private_data;

        qc->ap->ops->tf_read(qc->ap, &qc->tf);
        complete(waiting);
}

/**
 *      ata_exec_internal - execute libata internal command
 *      @ap: Port to which the command is sent
 *      @dev: Device to which the command is sent
 *      @tf: Taskfile registers for the command and the result
 *      @dma_dir: Data tranfer direction of the command
 *      @buf: Data buffer of the command
 *      @buflen: Length of data buffer
 *
 *      Executes libata internal command with timeout.  @tf contains
 *      command on entry and result on return.  Timeout and error
 *      conditions are reported via return value.  No recovery action
 *      is taken after a command times out.  It's caller's duty to
 *      clean up after timeout.
 *
 *      LOCKING:
 *      None.  Should be called with kernel context, might sleep.
 */

static unsigned
ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
                  struct ata_taskfile *tf,
                  int dma_dir, void *buf, unsigned int buflen)
{
        u8 command = tf->command;
        struct ata_queued_cmd *qc;
        DECLARE_COMPLETION(wait);
        unsigned long flags;
        unsigned int err_mask;

        spin_lock_irqsave(&ap->host_set->lock, flags);

        qc = ata_qc_new_init(ap, dev);
        BUG_ON(qc == NULL);

        qc->tf = *tf;
        qc->dma_dir = dma_dir;
        if (dma_dir != DMA_NONE) {
                ata_sg_init_one(qc, buf, buflen);
                qc->nsect = buflen / ATA_SECT_SIZE;
        }

        qc->private_data = &wait;
        qc->complete_fn = ata_qc_complete_internal;

        qc->err_mask = ata_qc_issue(qc);
        if (qc->err_mask)
                ata_qc_complete(qc);

        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        if (!wait_for_completion_timeout(&wait, ATA_TMOUT_INTERNAL)) {
                ata_port_flush_task(ap);

                spin_lock_irqsave(&ap->host_set->lock, flags);

                /* We're racing with irq here.  If we lose, the
                 * following test prevents us from completing the qc
                 * again.  If completion irq occurs after here but
                 * before the caller cleans up, it will result in a
                 * spurious interrupt.  We can live with that.
                 */
                if (qc->flags & ATA_QCFLAG_ACTIVE) {
                        qc->err_mask = AC_ERR_TIMEOUT;
                        ata_qc_complete(qc);
                        printk(KERN_WARNING "ata%u: qc timeout (cmd 0x%x)\n",
                               ap->id, command);
                }

                spin_unlock_irqrestore(&ap->host_set->lock, flags);
        }

        *tf = qc->tf;
        err_mask = qc->err_mask;

        ata_qc_free(qc);

        /* XXX - Some LLDDs (sata_mv) disable port on command failure.
         * Until those drivers are fixed, we detect the condition
         * here, fail the command with AC_ERR_SYSTEM and reenable the
         * port.
         *
         * Note that this doesn't change any behavior as internal
         * command failure results in disabling the device in the
         * higher layer for LLDDs without new reset/EH callbacks.
         *
         * Kill the following code as soon as those drivers are fixed.
         */
        if (ap->flags & ATA_FLAG_PORT_DISABLED) {
                err_mask |= AC_ERR_SYSTEM;
                ata_port_probe(ap);
        }

        return err_mask;
}

/**
 *      ata_pio_need_iordy      -       check if iordy needed
 *      @adev: ATA device
 *
 *      Check if the current speed of the device requires IORDY. Used
 *      by various controllers for chip configuration.
 */

unsigned int ata_pio_need_iordy(const struct ata_device *adev)
{
        int pio;
        int speed = adev->pio_mode - XFER_PIO_0;

        if (speed < 2)
                return 0;
        if (speed > 2)
                return 1;

        /* If we have no drive specific rule, then PIO 2 is non IORDY */

        if (adev->id[ATA_ID_FIELD_VALID] & 2) { /* EIDE */
                pio = adev->id[ATA_ID_EIDE_PIO];
                /* Is the speed faster than the drive allows non IORDY ? */
                if (pio) {
                        /* This is cycle times not frequency - watch the logic! */
                        if (pio > 240)  /* PIO2 is 240nS per cycle */
                                return 1;
                        return 0;
                }
        }
        return 0;
}

/**
 *      ata_dev_read_id - Read ID data from the specified device
 *      @ap: port on which target device resides
 *      @dev: target device
 *      @p_class: pointer to class of the target device (may be changed)
 *      @post_reset: is this read ID post-reset?
 *      @p_id: read IDENTIFY page (newly allocated)
 *
 *      Read ID data from the specified device.  ATA_CMD_ID_ATA is
 *      performed on ATA devices and ATA_CMD_ID_ATAPI on ATAPI
 *      devices.  This function also takes care of EDD signature
 *      misreporting (to be removed once EDD support is gone) and
 *      issues ATA_CMD_INIT_DEV_PARAMS for pre-ATA4 drives.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
static int ata_dev_read_id(struct ata_port *ap, struct ata_device *dev,
                           unsigned int *p_class, int post_reset, u16 **p_id)
{
        unsigned int class = *p_class;
        unsigned int using_edd;
        struct ata_taskfile tf;
        unsigned int err_mask = 0;
        u16 *id;
        const char *reason;
        int rc;

        DPRINTK("ENTER, host %u, dev %u\n", ap->id, dev->devno);

        if (ap->ops->probe_reset ||
            ap->flags & (ATA_FLAG_SRST | ATA_FLAG_SATA_RESET))
                using_edd = 0;
        else
                using_edd = 1;

        ata_dev_select(ap, dev->devno, 1, 1); /* select device 0/1 */

        id = kmalloc(sizeof(id[0]) * ATA_ID_WORDS, GFP_KERNEL);
        if (id == NULL) {
                rc = -ENOMEM;
                reason = "out of memory";
                goto err_out;
        }

 retry:
        ata_tf_init(ap, &tf, dev->devno);

        switch (class) {
        case ATA_DEV_ATA:
                tf.command = ATA_CMD_ID_ATA;
                break;
        case ATA_DEV_ATAPI:
                tf.command = ATA_CMD_ID_ATAPI;
                break;
        default:
                rc = -ENODEV;
                reason = "unsupported class";
                goto err_out;
        }

        tf.protocol = ATA_PROT_PIO;

        err_mask = ata_exec_internal(ap, dev, &tf, DMA_FROM_DEVICE,
                                     id, sizeof(id[0]) * ATA_ID_WORDS);

        if (err_mask) {
                rc = -EIO;
                reason = "I/O error";

                if (err_mask & ~AC_ERR_DEV)
                        goto err_out;

                /*
                 * arg!  EDD works for all test cases, but seems to return
                 * the ATA signature for some ATAPI devices.  Until the
                 * reason for this is found and fixed, we fix up the mess
                 * here.  If IDENTIFY DEVICE returns command aborted
                 * (as ATAPI devices do), then we issue an
                 * IDENTIFY PACKET DEVICE.
                 *
                 * ATA software reset (SRST, the default) does not appear
                 * to have this problem.
                 */
                if ((using_edd) && (class == ATA_DEV_ATA)) {
                        u8 err = tf.feature;
                        if (err & ATA_ABORTED) {
                                class = ATA_DEV_ATAPI;
                                goto retry;
                        }
                }
                goto err_out;
        }

        swap_buf_le16(id, ATA_ID_WORDS);

        /* sanity check */
        if ((class == ATA_DEV_ATA) != ata_id_is_ata(id)) {
                rc = -EINVAL;
                reason = "device reports illegal type";
                goto err_out;
        }

        if (post_reset && class == ATA_DEV_ATA) {
                /*
                 * The exact sequence expected by certain pre-ATA4 drives is:
                 * SRST RESET
                 * IDENTIFY
                 * INITIALIZE DEVICE PARAMETERS
                 * anything else..
                 * Some drives were very specific about that exact sequence.
                 */
                if (ata_id_major_version(id) < 4 || !ata_id_has_lba(id)) {
                        err_mask = ata_dev_init_params(ap, dev);
                        if (err_mask) {
                                rc = -EIO;
                                reason = "INIT_DEV_PARAMS failed";
                                goto err_out;
                        }

                        /* current CHS translation info (id[53-58]) might be
                         * changed. reread the identify device info.
                         */
                        post_reset = 0;
                        goto retry;
                }
        }

        *p_class = class;
        *p_id = id;
        return 0;

 err_out:
        printk(KERN_WARNING "ata%u: dev %u failed to IDENTIFY (%s)\n",
               ap->id, dev->devno, reason);
        kfree(id);
        return rc;
}

static inline u8 ata_dev_knobble(const struct ata_port *ap,
                                 struct ata_device *dev)
{
        return ((ap->cbl == ATA_CBL_SATA) && (!ata_id_is_sata(dev->id)));
}

/**
 *      ata_dev_configure - Configure the specified ATA/ATAPI device
 *      @ap: Port on which target device resides
 *      @dev: Target device to configure
 *      @print_info: Enable device info printout
 *
 *      Configure @dev according to @dev->id.  Generic and low-level
 *      driver specific fixups are also applied.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise
 */
static int ata_dev_configure(struct ata_port *ap, struct ata_device *dev,
                             int print_info)
{
        const u16 *id = dev->id;
        unsigned int xfer_mask;
        int i, rc;

        if (!ata_dev_present(dev)) {
                DPRINTK("ENTER/EXIT (host %u, dev %u) -- nodev\n",
                        ap->id, dev->devno);
                return 0;
        }

        DPRINTK("ENTER, host %u, dev %u\n", ap->id, dev->devno);

        /* print device capabilities */
        if (print_info)
                printk(KERN_DEBUG "ata%u: dev %u cfg 49:%04x 82:%04x 83:%04x "
                       "84:%04x 85:%04x 86:%04x 87:%04x 88:%04x\n",
                       ap->id, dev->devno, id[49], id[82], id[83],
                       id[84], id[85], id[86], id[87], id[88]);

        /* initialize to-be-configured parameters */
        dev->flags = 0;
        dev->max_sectors = 0;
        dev->cdb_len = 0;
        dev->n_sectors = 0;
        dev->cylinders = 0;
        dev->heads = 0;
        dev->sectors = 0;

        /*
         * common ATA, ATAPI feature tests
         */

        /* find max transfer mode; for printk only */
        xfer_mask = ata_id_xfermask(id);

        ata_dump_id(id);

        /* ATA-specific feature tests */
        if (dev->class == ATA_DEV_ATA) {
                dev->n_sectors = ata_id_n_sectors(id);

                if (ata_id_has_lba(id)) {
                        const char *lba_desc;

                        lba_desc = "LBA";
                        dev->flags |= ATA_DFLAG_LBA;
                        if (ata_id_has_lba48(id)) {
                                dev->flags |= ATA_DFLAG_LBA48;
                                lba_desc = "LBA48";
                        }

                        /* print device info to dmesg */
                        if (print_info)
                                printk(KERN_INFO "ata%u: dev %u ATA-%d, "
                                       "max %s, %Lu sectors: %s\n",
                                       ap->id, dev->devno,
                                       ata_id_major_version(id),
                                       ata_mode_string(xfer_mask),
                                       (unsigned long long)dev->n_sectors,
                                       lba_desc);
                } else {
                        /* CHS */

                        /* Default translation */
                        dev->cylinders  = id[1];
                        dev->heads      = id[3];
                        dev->sectors    = id[6];

                        if (ata_id_current_chs_valid(id)) {
                                /* Current CHS translation is valid. */
                                dev->cylinders = id[54];
                                dev->heads     = id[55];
                                dev->sectors   = id[56];
                        }

                        /* print device info to dmesg */
                        if (print_info)
                                printk(KERN_INFO "ata%u: dev %u ATA-%d, "
                                       "max %s, %Lu sectors: CHS %u/%u/%u\n",
                                       ap->id, dev->devno,
                                       ata_id_major_version(id),
                                       ata_mode_string(xfer_mask),
                                       (unsigned long long)dev->n_sectors,
                                       dev->cylinders, dev->heads, dev->sectors);
                }

                dev->cdb_len = 16;
        }

        /* ATAPI-specific feature tests */
        else if (dev->class == ATA_DEV_ATAPI) {
                rc = atapi_cdb_len(id);
                if ((rc < 12) || (rc > ATAPI_CDB_LEN)) {
                        printk(KERN_WARNING "ata%u: unsupported CDB len\n", ap->id);
                        rc = -EINVAL;
                        goto err_out_nosup;
                }
                dev->cdb_len = (unsigned int) rc;

                /* print device info to dmesg */
                if (print_info)
                        printk(KERN_INFO "ata%u: dev %u ATAPI, max %s\n",
                               ap->id, dev->devno, ata_mode_string(xfer_mask));
        }

        ap->host->max_cmd_len = 0;
        for (i = 0; i < ATA_MAX_DEVICES; i++)
                ap->host->max_cmd_len = max_t(unsigned int,
                                              ap->host->max_cmd_len,
                                              ap->device[i].cdb_len);

        /* limit bridge transfers to udma5, 200 sectors */
        if (ata_dev_knobble(ap, dev)) {
                if (print_info)
                        printk(KERN_INFO "ata%u(%u): applying bridge limits\n",
                               ap->id, dev->devno);
                dev->udma_mask &= ATA_UDMA5;
                dev->max_sectors = ATA_MAX_SECTORS;
        }

        if (ap->ops->dev_config)
                ap->ops->dev_config(ap, dev);

        DPRINTK("EXIT, drv_stat = 0x%x\n", ata_chk_status(ap));
        return 0;

err_out_nosup:
        DPRINTK("EXIT, err\n");
        return rc;
}

/**
 *      ata_bus_probe - Reset and probe ATA bus
 *      @ap: Bus to probe
 *
 *      Master ATA bus probing function.  Initiates a hardware-dependent
 *      bus reset, then attempts to identify any devices found on
 *      the bus.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      Zero on success, non-zero on error.
 */

static int ata_bus_probe(struct ata_port *ap)
{
        unsigned int classes[ATA_MAX_DEVICES];
        unsigned int i, rc, found = 0;

        ata_port_probe(ap);

        /* reset and determine device classes */
        for (i = 0; i < ATA_MAX_DEVICES; i++)
                classes[i] = ATA_DEV_UNKNOWN;

        if (ap->ops->probe_reset) {
                rc = ap->ops->probe_reset(ap, classes);
                if (rc) {
                        printk("ata%u: reset failed (errno=%d)\n", ap->id, rc);
                        return rc;
                }
        } else {
                ap->ops->phy_reset(ap);

                if (!(ap->flags & ATA_FLAG_PORT_DISABLED))
                        for (i = 0; i < ATA_MAX_DEVICES; i++)
                                classes[i] = ap->device[i].class;

                ata_port_probe(ap);
        }

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                if (classes[i] == ATA_DEV_UNKNOWN)
                        classes[i] = ATA_DEV_NONE;

        /* read IDENTIFY page and configure devices */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];

                dev->class = classes[i];

                if (!ata_dev_present(dev))
                        continue;

                WARN_ON(dev->id != NULL);
                if (ata_dev_read_id(ap, dev, &dev->class, 1, &dev->id)) {
                        dev->class = ATA_DEV_NONE;
                        continue;
                }

                if (ata_dev_configure(ap, dev, 1)) {
                        ata_dev_disable(ap, dev);
                        continue;
                }

                found = 1;
        }

        if (!found)
                goto err_out_disable;

        ata_set_mode(ap);
        if (ap->flags & ATA_FLAG_PORT_DISABLED)
                goto err_out_disable;

        return 0;

err_out_disable:
        ap->ops->port_disable(ap);
        return -1;
}

/**
 *      ata_port_probe - Mark port as enabled
 *      @ap: Port for which we indicate enablement
 *
 *      Modify @ap data structure such that the system
 *      thinks that the entire port is enabled.
 *
 *      LOCKING: host_set lock, or some other form of
 *      serialization.
 */

void ata_port_probe(struct ata_port *ap)
{
        ap->flags &= ~ATA_FLAG_PORT_DISABLED;
}

/**
 *      sata_print_link_status - Print SATA link status
 *      @ap: SATA port to printk link status about
 *
 *      This function prints link speed and status of a SATA link.
 *
 *      LOCKING:
 *      None.
 */
static void sata_print_link_status(struct ata_port *ap)
{
        u32 sstatus, tmp;
        const char *speed;

        if (!ap->ops->scr_read)
                return;

        sstatus = scr_read(ap, SCR_STATUS);

        if (sata_dev_present(ap)) {
                tmp = (sstatus >> 4) & 0xf;
                if (tmp & (1 << 0))
                        speed = "1.5";
                else if (tmp & (1 << 1))
                        speed = "3.0";
                else
                        speed = "<unknown>";
                printk(KERN_INFO "ata%u: SATA link up %s Gbps (SStatus %X)\n",
                       ap->id, speed, sstatus);
        } else {
                printk(KERN_INFO "ata%u: SATA link down (SStatus %X)\n",
                       ap->id, sstatus);
        }
}

/**
 *      __sata_phy_reset - Wake/reset a low-level SATA PHY
 *      @ap: SATA port associated with target SATA PHY.
 *
 *      This function issues commands to standard SATA Sxxx
 *      PHY registers, to wake up the phy (and device), and
 *      clear any reset condition.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 */
void __sata_phy_reset(struct ata_port *ap)
{
        u32 sstatus;
        unsigned long timeout = jiffies + (HZ * 5);

        if (ap->flags & ATA_FLAG_SATA_RESET) {
                /* issue phy wake/reset */
                scr_write_flush(ap, SCR_CONTROL, 0x301);
                /* Couldn't find anything in SATA I/II specs, but
                 * AHCI-1.1 10.4.2 says at least 1 ms. */
                mdelay(1);
        }
        scr_write_flush(ap, SCR_CONTROL, 0x300); /* phy wake/clear reset */

        /* wait for phy to become ready, if necessary */
        do {
                msleep(200);
                sstatus = scr_read(ap, SCR_STATUS);
                if ((sstatus & 0xf) != 1)
                        break;
        } while (time_before(jiffies, timeout));

        /* print link status */
        sata_print_link_status(ap);

        /* TODO: phy layer with polling, timeouts, etc. */
        if (sata_dev_present(ap))
                ata_port_probe(ap);
        else
                ata_port_disable(ap);

        if (ap->flags & ATA_FLAG_PORT_DISABLED)
                return;

        if (ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT)) {
                ata_port_disable(ap);
                return;
        }

        ap->cbl = ATA_CBL_SATA;
}

/**
 *      sata_phy_reset - Reset SATA bus.
 *      @ap: SATA port associated with target SATA PHY.
 *
 *      This function resets the SATA bus, and then probes
 *      the bus for devices.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 */
void sata_phy_reset(struct ata_port *ap)
{
        __sata_phy_reset(ap);
        if (ap->flags & ATA_FLAG_PORT_DISABLED)
                return;
        ata_bus_reset(ap);
}

/**
 *      ata_dev_pair            -       return other device on cable
 *      @ap: port
 *      @adev: device
 *
 *      Obtain the other device on the same cable, or if none is
 *      present NULL is returned
 */

struct ata_device *ata_dev_pair(struct ata_port *ap, struct ata_device *adev)
{
        struct ata_device *pair = &ap->device[1 - adev->devno];
        if (!ata_dev_present(pair))
                return NULL;
        return pair;
}

/**
 *      ata_port_disable - Disable port.
 *      @ap: Port to be disabled.
 *
 *      Modify @ap data structure such that the system
 *      thinks that the entire port is disabled, and should
 *      never attempt to probe or communicate with devices
 *      on this port.
 *
 *      LOCKING: host_set lock, or some other form of
 *      serialization.
 */

void ata_port_disable(struct ata_port *ap)
{
        ap->device[0].class = ATA_DEV_NONE;
        ap->device[1].class = ATA_DEV_NONE;
        ap->flags |= ATA_FLAG_PORT_DISABLED;
}

/*
 * This mode timing computation functionality is ported over from
 * drivers/ide/ide-timing.h and was originally written by Vojtech Pavlik
 */
/*
 * PIO 0-5, MWDMA 0-2 and UDMA 0-6 timings (in nanoseconds).
 * These were taken from ATA/ATAPI-6 standard, rev 0a, except
 * for PIO 5, which is a nonstandard extension and UDMA6, which
 * is currently supported only by Maxtor drives.
 */

static const struct ata_timing ata_timing[] = {

        { XFER_UDMA_6,     0,   0,   0,   0,   0,   0,   0,  15 },
        { XFER_UDMA_5,     0,   0,   0,   0,   0,   0,   0,  20 },
        { XFER_UDMA_4,     0,   0,   0,   0,   0,   0,   0,  30 },
        { XFER_UDMA_3,     0,   0,   0,   0,   0,   0,   0,  45 },

        { XFER_UDMA_2,     0,   0,   0,   0,   0,   0,   0,  60 },
        { XFER_UDMA_1,     0,   0,   0,   0,   0,   0,   0,  80 },
        { XFER_UDMA_0,     0,   0,   0,   0,   0,   0,   0, 120 },

/*      { XFER_UDMA_SLOW,  0,   0,   0,   0,   0,   0,   0, 150 }, */

        { XFER_MW_DMA_2,  25,   0,   0,   0,  70,  25, 120,   0 },
        { XFER_MW_DMA_1,  45,   0,   0,   0,  80,  50, 150,   0 },
        { XFER_MW_DMA_0,  60,   0,   0,   0, 215, 215, 480,   0 },

        { XFER_SW_DMA_2,  60,   0,   0,   0, 120, 120, 240,   0 },
        { XFER_SW_DMA_1,  90,   0,   0,   0, 240, 240, 480,   0 },
        { XFER_SW_DMA_0, 120,   0,   0,   0, 480, 480, 960,   0 },

/*      { XFER_PIO_5,     20,  50,  30, 100,  50,  30, 100,   0 }, */
        { XFER_PIO_4,     25,  70,  25, 120,  70,  25, 120,   0 },
        { XFER_PIO_3,     30,  80,  70, 180,  80,  70, 180,   0 },

        { XFER_PIO_2,     30, 290,  40, 330, 100,  90, 240,   0 },
        { XFER_PIO_1,     50, 290,  93, 383, 125, 100, 383,   0 },
        { XFER_PIO_0,     70, 290, 240, 600, 165, 150, 600,   0 },

/*      { XFER_PIO_SLOW, 120, 290, 240, 960, 290, 240, 960,   0 }, */

        { 0xFF }
};

#define ENOUGH(v,unit)          (((v)-1)/(unit)+1)
#define EZ(v,unit)              ((v)?ENOUGH(v,unit):0)

static void ata_timing_quantize(const struct ata_timing *t, struct ata_timing *q, int T, int UT)
{
        q->setup   = EZ(t->setup   * 1000,  T);
        q->act8b   = EZ(t->act8b   * 1000,  T);
        q->rec8b   = EZ(t->rec8b   * 1000,  T);
        q->cyc8b   = EZ(t->cyc8b   * 1000,  T);
        q->active  = EZ(t->active  * 1000,  T);
        q->recover = EZ(t->recover * 1000,  T);
        q->cycle   = EZ(t->cycle   * 1000,  T);
        q->udma    = EZ(t->udma    * 1000, UT);
}

void ata_timing_merge(const struct ata_timing *a, const struct ata_timing *b,
                      struct ata_timing *m, unsigned int what)
{
        if (what & ATA_TIMING_SETUP  ) m->setup   = max(a->setup,   b->setup);
        if (what & ATA_TIMING_ACT8B  ) m->act8b   = max(a->act8b,   b->act8b);
        if (what & ATA_TIMING_REC8B  ) m->rec8b   = max(a->rec8b,   b->rec8b);
        if (what & ATA_TIMING_CYC8B  ) m->cyc8b   = max(a->cyc8b,   b->cyc8b);
        if (what & ATA_TIMING_ACTIVE ) m->active  = max(a->active,  b->active);
        if (what & ATA_TIMING_RECOVER) m->recover = max(a->recover, b->recover);
        if (what & ATA_TIMING_CYCLE  ) m->cycle   = max(a->cycle,   b->cycle);
        if (what & ATA_TIMING_UDMA   ) m->udma    = max(a->udma,    b->udma);
}

static const struct ata_timing* ata_timing_find_mode(unsigned short speed)
{
        const struct ata_timing *t;

        for (t = ata_timing; t->mode != speed; t++)
                if (t->mode == 0xFF)
                        return NULL;
        return t;
}

int ata_timing_compute(struct ata_device *adev, unsigned short speed,
                       struct ata_timing *t, int T, int UT)
{
        const struct ata_timing *s;
        struct ata_timing p;

        /*
         * Find the mode.
         */

        if (!(s = ata_timing_find_mode(speed)))
                return -EINVAL;

        memcpy(t, s, sizeof(*s));

        /*
         * If the drive is an EIDE drive, it can tell us it needs extended
         * PIO/MW_DMA cycle timing.
         */

        if (adev->id[ATA_ID_FIELD_VALID] & 2) { /* EIDE drive */
                memset(&p, 0, sizeof(p));
                if(speed >= XFER_PIO_0 && speed <= XFER_SW_DMA_0) {
                        if (speed <= XFER_PIO_2) p.cycle = p.cyc8b = adev->id[ATA_ID_EIDE_PIO];
                                            else p.cycle = p.cyc8b = adev->id[ATA_ID_EIDE_PIO_IORDY];
                } else if(speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2) {
                        p.cycle = adev->id[ATA_ID_EIDE_DMA_MIN];
                }
                ata_timing_merge(&p, t, t, ATA_TIMING_CYCLE | ATA_TIMING_CYC8B);
        }

        /*
         * Convert the timing to bus clock counts.
         */

        ata_timing_quantize(t, t, T, UT);

        /*
         * Even in DMA/UDMA modes we still use PIO access for IDENTIFY,
         * S.M.A.R.T * and some other commands. We have to ensure that the
         * DMA cycle timing is slower/equal than the fastest PIO timing.
         */

        if (speed > XFER_PIO_4) {
                ata_timing_compute(adev, adev->pio_mode, &p, T, UT);
                ata_timing_merge(&p, t, t, ATA_TIMING_ALL);
        }

        /*
         * Lengthen active & recovery time so that cycle time is correct.
         */

        if (t->act8b + t->rec8b < t->cyc8b) {
                t->act8b += (t->cyc8b - (t->act8b + t->rec8b)) / 2;
                t->rec8b = t->cyc8b - t->act8b;
        }

        if (t->active + t->recover < t->cycle) {
                t->active += (t->cycle - (t->active + t->recover)) / 2;
                t->recover = t->cycle - t->active;
        }

        return 0;
}

static int ata_dev_set_mode(struct ata_port *ap, struct ata_device *dev)
{
        unsigned int err_mask;
        int rc;

        if (dev->xfer_shift == ATA_SHIFT_PIO)
                dev->flags |= ATA_DFLAG_PIO;

        err_mask = ata_dev_set_xfermode(ap, dev);
        if (err_mask) {
                printk(KERN_ERR
                       "ata%u: failed to set xfermode (err_mask=0x%x)\n",
                       ap->id, err_mask);
                return -EIO;
        }

        rc = ata_dev_revalidate(ap, dev, 0);
        if (rc) {
                printk(KERN_ERR
                       "ata%u: failed to revalidate after set xfermode\n",
                       ap->id);
                return rc;
        }

        DPRINTK("xfer_shift=%u, xfer_mode=0x%x\n",
                dev->xfer_shift, (int)dev->xfer_mode);

        printk(KERN_INFO "ata%u: dev %u configured for %s\n",
               ap->id, dev->devno,
               ata_mode_string(ata_xfer_mode2mask(dev->xfer_mode)));
        return 0;
}

static int ata_host_set_pio(struct ata_port *ap)
{
        int i;

        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];

                if (!ata_dev_present(dev))
                        continue;

                if (!dev->pio_mode) {
                        printk(KERN_WARNING "ata%u: no PIO support for device %d.\n", ap->id, i);
                        return -1;
                }

                dev->xfer_mode = dev->pio_mode;
                dev->xfer_shift = ATA_SHIFT_PIO;
                if (ap->ops->set_piomode)
                        ap->ops->set_piomode(ap, dev);
        }

        return 0;
}

static void ata_host_set_dma(struct ata_port *ap)
{
        int i;

        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];

                if (!ata_dev_present(dev) || !dev->dma_mode)
                        continue;

                dev->xfer_mode = dev->dma_mode;
                dev->xfer_shift = ata_xfer_mode2shift(dev->dma_mode);
                if (ap->ops->set_dmamode)
                        ap->ops->set_dmamode(ap, dev);
        }
}

/**
 *      ata_set_mode - Program timings and issue SET FEATURES - XFER
 *      @ap: port on which timings will be programmed
 *
 *      Set ATA device disk transfer mode (PIO3, UDMA6, etc.).
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 */
static void ata_set_mode(struct ata_port *ap)
{
        int i, rc;

        /* step 1: calculate xfer_mask */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];
                unsigned int pio_mask, dma_mask;

                if (!ata_dev_present(dev))
                        continue;

                ata_dev_xfermask(ap, dev);

                /* TODO: let LLDD filter dev->*_mask here */

                pio_mask = ata_pack_xfermask(dev->pio_mask, 0, 0);
                dma_mask = ata_pack_xfermask(0, dev->mwdma_mask, dev->udma_mask);
                dev->pio_mode = ata_xfer_mask2mode(pio_mask);
                dev->dma_mode = ata_xfer_mask2mode(dma_mask);
        }

        /* step 2: always set host PIO timings */
        rc = ata_host_set_pio(ap);
        if (rc)
                goto err_out;

        /* step 3: set host DMA timings */
        ata_host_set_dma(ap);

        /* step 4: update devices' xfer mode */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];

                if (!ata_dev_present(dev))
                        continue;

                if (ata_dev_set_mode(ap, dev))
                        goto err_out;
        }

        if (ap->ops->post_set_mode)
                ap->ops->post_set_mode(ap);

        return;

err_out:
        ata_port_disable(ap);
}

/**
 *      ata_tf_to_host - issue ATA taskfile to host controller
 *      @ap: port to which command is being issued
 *      @tf: ATA taskfile register set
 *
 *      Issues ATA taskfile register set to ATA host controller,
 *      with proper synchronization with interrupt handler and
 *      other threads.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static inline void ata_tf_to_host(struct ata_port *ap,
                                  const struct ata_taskfile *tf)
{
        ap->ops->tf_load(ap, tf);
        ap->ops->exec_command(ap, tf);
}

/**
 *      ata_busy_sleep - sleep until BSY clears, or timeout
 *      @ap: port containing status register to be polled
 *      @tmout_pat: impatience timeout
 *      @tmout: overall timeout
 *
 *      Sleep until ATA Status register bit BSY clears,
 *      or a timeout occurs.
 *
 *      LOCKING: None.
 */

unsigned int ata_busy_sleep (struct ata_port *ap,
                             unsigned long tmout_pat, unsigned long tmout)
{
        unsigned long timer_start, timeout;
        u8 status;

        status = ata_busy_wait(ap, ATA_BUSY, 300);
        timer_start = jiffies;
        timeout = timer_start + tmout_pat;
        while ((status & ATA_BUSY) && (time_before(jiffies, timeout))) {
                msleep(50);
                status = ata_busy_wait(ap, ATA_BUSY, 3);
        }

        if (status & ATA_BUSY)
                printk(KERN_WARNING "ata%u is slow to respond, "
                       "please be patient\n", ap->id);

        timeout = timer_start + tmout;
        while ((status & ATA_BUSY) && (time_before(jiffies, timeout))) {
                msleep(50);
                status = ata_chk_status(ap);
        }

        if (status & ATA_BUSY) {
                printk(KERN_ERR "ata%u failed to respond (%lu secs)\n",
                       ap->id, tmout / HZ);
                return 1;
        }

        return 0;
}

static void ata_bus_post_reset(struct ata_port *ap, unsigned int devmask)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int dev0 = devmask & (1 << 0);
        unsigned int dev1 = devmask & (1 << 1);
        unsigned long timeout;

        /* if device 0 was found in ata_devchk, wait for its
         * BSY bit to clear
         */
        if (dev0)
                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

        /* if device 1 was found in ata_devchk, wait for
         * register access, then wait for BSY to clear
         */
        timeout = jiffies + ATA_TMOUT_BOOT;
        while (dev1) {
                u8 nsect, lbal;

                ap->ops->dev_select(ap, 1);
                if (ap->flags & ATA_FLAG_MMIO) {
                        nsect = readb((void __iomem *) ioaddr->nsect_addr);
                        lbal = readb((void __iomem *) ioaddr->lbal_addr);
                } else {
                        nsect = inb(ioaddr->nsect_addr);
                        lbal = inb(ioaddr->lbal_addr);
                }
                if ((nsect == 1) && (lbal == 1))
                        break;
                if (time_after(jiffies, timeout)) {
                        dev1 = 0;
                        break;
                }
                msleep(50);     /* give drive a breather */
        }
        if (dev1)
                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

        /* is all this really necessary? */
        ap->ops->dev_select(ap, 0);
        if (dev1)
                ap->ops->dev_select(ap, 1);
        if (dev0)
                ap->ops->dev_select(ap, 0);
}

/**
 *      ata_bus_edd - Issue EXECUTE DEVICE DIAGNOSTIC command.
 *      @ap: Port to reset and probe
 *
 *      Use the EXECUTE DEVICE DIAGNOSTIC command to reset and
 *      probe the bus.  Not often used these days.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *      Obtains host_set lock.
 *
 */

static unsigned int ata_bus_edd(struct ata_port *ap)
{
        struct ata_taskfile tf;
        unsigned long flags;

        /* set up execute-device-diag (bus reset) taskfile */
        /* also, take interrupts to a known state (disabled) */
        DPRINTK("execute-device-diag\n");
        ata_tf_init(ap, &tf, 0);
        tf.ctl |= ATA_NIEN;
        tf.command = ATA_CMD_EDD;
        tf.protocol = ATA_PROT_NODATA;

        /* do bus reset */
        spin_lock_irqsave(&ap->host_set->lock, flags);
        ata_tf_to_host(ap, &tf);
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        /* spec says at least 2ms.  but who knows with those
         * crazy ATAPI devices...
         */
        msleep(150);

        return ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
}

static unsigned int ata_bus_softreset(struct ata_port *ap,
                                      unsigned int devmask)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;

        DPRINTK("ata%u: bus reset via SRST\n", ap->id);

        /* software reset.  causes dev0 to be selected */
        if (ap->flags & ATA_FLAG_MMIO) {
                writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                udelay(20);     /* FIXME: flush */
                writeb(ap->ctl | ATA_SRST, (void __iomem *) ioaddr->ctl_addr);
                udelay(20);     /* FIXME: flush */
                writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
        } else {
                outb(ap->ctl, ioaddr->ctl_addr);
                udelay(10);
                outb(ap->ctl | ATA_SRST, ioaddr->ctl_addr);
                udelay(10);
                outb(ap->ctl, ioaddr->ctl_addr);
        }

        /* spec mandates ">= 2ms" before checking status.
         * We wait 150ms, because that was the magic delay used for
         * ATAPI devices in Hale Landis's ATADRVR, for the period of time
         * between when the ATA command register is written, and then
         * status is checked.  Because waiting for "a while" before
         * checking status is fine, post SRST, we perform this magic
         * delay here as well.
         *
         * Old drivers/ide uses the 2mS rule and then waits for ready
         */
        msleep(150);


        /* Before we perform post reset processing we want to see if
           the bus shows 0xFF because the odd clown forgets the D7 pulldown
           resistor */

        if (ata_check_status(ap) == 0xFF)
                return 1;       /* Positive is failure for some reason */

        ata_bus_post_reset(ap, devmask);

        return 0;
}

/**
 *      ata_bus_reset - reset host port and associated ATA channel
 *      @ap: port to reset
 *
 *      This is typically the first time we actually start issuing
 *      commands to the ATA channel.  We wait for BSY to clear, then
 *      issue EXECUTE DEVICE DIAGNOSTIC command, polling for its
 *      result.  Determine what devices, if any, are on the channel
 *      by looking at the device 0/1 error register.  Look at the signature
 *      stored in each device's taskfile registers, to determine if
 *      the device is ATA or ATAPI.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *      Obtains host_set lock.
 *
 *      SIDE EFFECTS:
 *      Sets ATA_FLAG_PORT_DISABLED if bus reset fails.
 */

void ata_bus_reset(struct ata_port *ap)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        u8 err;
        unsigned int dev0, dev1 = 0, rc = 0, devmask = 0;

        DPRINTK("ENTER, host %u, port %u\n", ap->id, ap->port_no);

        /* determine if device 0/1 are present */
        if (ap->flags & ATA_FLAG_SATA_RESET)
                dev0 = 1;
        else {
                dev0 = ata_devchk(ap, 0);
                if (slave_possible)
                        dev1 = ata_devchk(ap, 1);
        }

        if (dev0)
                devmask |= (1 << 0);
        if (dev1)
                devmask |= (1 << 1);

        /* select device 0 again */
        ap->ops->dev_select(ap, 0);

        /* issue bus reset */
        if (ap->flags & ATA_FLAG_SRST)
                rc = ata_bus_softreset(ap, devmask);
        else if ((ap->flags & ATA_FLAG_SATA_RESET) == 0) {
                /* set up device control */
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                else
                        outb(ap->ctl, ioaddr->ctl_addr);
                rc = ata_bus_edd(ap);
        }

        if (rc)
                goto err_out;

        /*
         * determine by signature whether we have ATA or ATAPI devices
         */
        ap->device[0].class = ata_dev_try_classify(ap, 0, &err);
        if ((slave_possible) && (err != 0x81))
                ap->device[1].class = ata_dev_try_classify(ap, 1, &err);

        /* re-enable interrupts */
        if (ap->ioaddr.ctl_addr)        /* FIXME: hack. create a hook instead */
                ata_irq_on(ap);

        /* is double-select really necessary? */
        if (ap->device[1].class != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 1);
        if (ap->device[0].class != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 0);

        /* if no devices were detected, disable this port */
        if ((ap->device[0].class == ATA_DEV_NONE) &&
            (ap->device[1].class == ATA_DEV_NONE))
                goto err_out;

        if (ap->flags & (ATA_FLAG_SATA_RESET | ATA_FLAG_SRST)) {
                /* set up device control for ATA_FLAG_SATA_RESET */
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                else
                        outb(ap->ctl, ioaddr->ctl_addr);
        }

        DPRINTK("EXIT\n");
        return;

err_out:
        printk(KERN_ERR "ata%u: disabling port\n", ap->id);
        ap->ops->port_disable(ap);

        DPRINTK("EXIT\n");
}

static int sata_phy_resume(struct ata_port *ap)
{
        unsigned long timeout = jiffies + (HZ * 5);
        u32 sstatus;

        scr_write_flush(ap, SCR_CONTROL, 0x300);

        /* Wait for phy to become ready, if necessary. */
        do {
                msleep(200);
                sstatus = scr_read(ap, SCR_STATUS);
                if ((sstatus & 0xf) != 1)
                        return 0;
        } while (time_before(jiffies, timeout));

        return -1;
}

/**
 *      ata_std_probeinit - initialize probing
 *      @ap: port to be probed
 *
 *      @ap is about to be probed.  Initialize it.  This function is
 *      to be used as standard callback for ata_drive_probe_reset().
 *
 *      NOTE!!! Do not use this function as probeinit if a low level
 *      driver implements only hardreset.  Just pass NULL as probeinit
 *      in that case.  Using this function is probably okay but doing
 *      so makes reset sequence different from the original
 *      ->phy_reset implementation and Jeff nervous.  :-P
 */
extern void ata_std_probeinit(struct ata_port *ap)
{
        if (ap->flags & ATA_FLAG_SATA && ap->ops->scr_read) {
                sata_phy_resume(ap);
                if (sata_dev_present(ap))
                        ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
        }
}

/**
 *      ata_std_softreset - reset host port via ATA SRST
 *      @ap: port to reset
 *      @verbose: fail verbosely
 *      @classes: resulting classes of attached devices
 *
 *      Reset host port using ATA SRST.  This function is to be used
 *      as standard callback for ata_drive_*_reset() functions.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_std_softreset(struct ata_port *ap, int verbose, unsigned int *classes)
{
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        unsigned int devmask = 0, err_mask;
        u8 err;

        DPRINTK("ENTER\n");

        if (ap->ops->scr_read && !sata_dev_present(ap)) {
                classes[0] = ATA_DEV_NONE;
                goto out;
        }

        /* determine if device 0/1 are present */
        if (ata_devchk(ap, 0))
                devmask |= (1 << 0);
        if (slave_possible && ata_devchk(ap, 1))
                devmask |= (1 << 1);

        /* select device 0 again */
        ap->ops->dev_select(ap, 0);

        /* issue bus reset */
        DPRINTK("about to softreset, devmask=%x\n", devmask);
        err_mask = ata_bus_softreset(ap, devmask);
        if (err_mask) {
                if (verbose)
                        printk(KERN_ERR "ata%u: SRST failed (err_mask=0x%x)\n",
                               ap->id, err_mask);
                else
                        DPRINTK("EXIT, softreset failed (err_mask=0x%x)\n",
                                err_mask);
                return -EIO;
        }

        /* determine by signature whether we have ATA or ATAPI devices */
        classes[0] = ata_dev_try_classify(ap, 0, &err);
        if (slave_possible && err != 0x81)
                classes[1] = ata_dev_try_classify(ap, 1, &err);

 out:
        DPRINTK("EXIT, classes[0]=%u [1]=%u\n", classes[0], classes[1]);
        return 0;
}

/**
 *      sata_std_hardreset - reset host port via SATA phy reset
 *      @ap: port to reset
 *      @verbose: fail verbosely
 *      @class: resulting class of attached device
 *
 *      SATA phy-reset host port using DET bits of SControl register.
 *      This function is to be used as standard callback for
 *      ata_drive_*_reset().
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int sata_std_hardreset(struct ata_port *ap, int verbose, unsigned int *class)
{
        DPRINTK("ENTER\n");

        /* Issue phy wake/reset */
        scr_write_flush(ap, SCR_CONTROL, 0x301);

        /*
         * Couldn't find anything in SATA I/II specs, but AHCI-1.1
         * 10.4.2 says at least 1 ms.
         */
        msleep(1);

        /* Bring phy back */
        sata_phy_resume(ap);

        /* TODO: phy layer with polling, timeouts, etc. */
        if (!sata_dev_present(ap)) {
                *class = ATA_DEV_NONE;
                DPRINTK("EXIT, link offline\n");
                return 0;
        }

        if (ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT)) {
                if (verbose)
                        printk(KERN_ERR "ata%u: COMRESET failed "
                               "(device not ready)\n", ap->id);
                else
                        DPRINTK("EXIT, device not ready\n");
                return -EIO;
        }

        ap->ops->dev_select(ap, 0);     /* probably unnecessary */

        *class = ata_dev_try_classify(ap, 0, NULL);

        DPRINTK("EXIT, class=%u\n", *class);
        return 0;
}

/**
 *      ata_std_postreset - standard postreset callback
 *      @ap: the target ata_port
 *      @classes: classes of attached devices
 *
 *      This function is invoked after a successful reset.  Note that
 *      the device might have been reset more than once using
 *      different reset methods before postreset is invoked.
 *
 *      This function is to be used as standard callback for
 *      ata_drive_*_reset().
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_std_postreset(struct ata_port *ap, unsigned int *classes)
{
        DPRINTK("ENTER\n");

        /* set cable type if it isn't already set */
        if (ap->cbl == ATA_CBL_NONE && ap->flags & ATA_FLAG_SATA)
                ap->cbl = ATA_CBL_SATA;

        /* print link status */
        if (ap->cbl == ATA_CBL_SATA)
                sata_print_link_status(ap);

        /* re-enable interrupts */
        if (ap->ioaddr.ctl_addr)        /* FIXME: hack. create a hook instead */
                ata_irq_on(ap);

        /* is double-select really necessary? */
        if (classes[0] != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 1);
        if (classes[1] != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 0);

        /* bail out if no device is present */
        if (classes[0] == ATA_DEV_NONE && classes[1] == ATA_DEV_NONE) {
                DPRINTK("EXIT, no device\n");
                return;
        }

        /* set up device control */
        if (ap->ioaddr.ctl_addr) {
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ap->ioaddr.ctl_addr);
                else
                        outb(ap->ctl, ap->ioaddr.ctl_addr);
        }

        DPRINTK("EXIT\n");
}

/**
 *      ata_std_probe_reset - standard probe reset method
 *      @ap: prot to perform probe-reset
 *      @classes: resulting classes of attached devices
 *
 *      The stock off-the-shelf ->probe_reset method.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_std_probe_reset(struct ata_port *ap, unsigned int *classes)
{
        ata_reset_fn_t hardreset;

        hardreset = NULL;
        if (ap->flags & ATA_FLAG_SATA && ap->ops->scr_read)
                hardreset = sata_std_hardreset;

        return ata_drive_probe_reset(ap, ata_std_probeinit,
                                     ata_std_softreset, hardreset,
                                     ata_std_postreset, classes);
}

static int do_probe_reset(struct ata_port *ap, ata_reset_fn_t reset,
                          ata_postreset_fn_t postreset,
                          unsigned int *classes)
{
        int i, rc;

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                classes[i] = ATA_DEV_UNKNOWN;

        rc = reset(ap, 0, classes);
        if (rc)
                return rc;

        /* If any class isn't ATA_DEV_UNKNOWN, consider classification
         * is complete and convert all ATA_DEV_UNKNOWN to
         * ATA_DEV_NONE.
         */
        for (i = 0; i < ATA_MAX_DEVICES; i++)
                if (classes[i] != ATA_DEV_UNKNOWN)
                        break;

        if (i < ATA_MAX_DEVICES)
                for (i = 0; i < ATA_MAX_DEVICES; i++)
                        if (classes[i] == ATA_DEV_UNKNOWN)
                                classes[i] = ATA_DEV_NONE;

        if (postreset)
                postreset(ap, classes);

        return classes[0] != ATA_DEV_UNKNOWN ? 0 : -ENODEV;
}

/**
 *      ata_drive_probe_reset - Perform probe reset with given methods
 *      @ap: port to reset
 *      @probeinit: probeinit method (can be NULL)
 *      @softreset: softreset method (can be NULL)
 *      @hardreset: hardreset method (can be NULL)
 *      @postreset: postreset method (can be NULL)
 *      @classes: resulting classes of attached devices
 *
 *      Reset the specified port and classify attached devices using
 *      given methods.  This function prefers softreset but tries all
 *      possible reset sequences to reset and classify devices.  This
 *      function is intended to be used for constructing ->probe_reset
 *      callback by low level drivers.
 *
 *      Reset methods should follow the following rules.
 *
 *      - Return 0 on sucess, -errno on failure.
 *      - If classification is supported, fill classes[] with
 *        recognized class codes.
 *      - If classification is not supported, leave classes[] alone.
 *      - If verbose is non-zero, print error message on failure;
 *        otherwise, shut up.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -EINVAL if no reset method is avaliable, -ENODEV
 *      if classification fails, and any error code from reset
 *      methods.
 */
int ata_drive_probe_reset(struct ata_port *ap, ata_probeinit_fn_t probeinit,
                          ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
                          ata_postreset_fn_t postreset, unsigned int *classes)
{
        int rc = -EINVAL;

        if (probeinit)
                probeinit(ap);

        if (softreset) {
                rc = do_probe_reset(ap, softreset, postreset, classes);
                if (rc == 0)
                        return 0;
        }

        if (!hardreset)
                return rc;

        rc = do_probe_reset(ap, hardreset, postreset, classes);
        if (rc == 0 || rc != -ENODEV)
                return rc;

        if (softreset)
                rc = do_probe_reset(ap, softreset, postreset, classes);

        return rc;
}

/**
 *      ata_dev_same_device - Determine whether new ID matches configured device
 *      @ap: port on which the device to compare against resides
 *      @dev: device to compare against
 *      @new_class: class of the new device
 *      @new_id: IDENTIFY page of the new device
 *
 *      Compare @new_class and @new_id against @dev and determine
 *      whether @dev is the device indicated by @new_class and
 *      @new_id.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      1 if @dev matches @new_class and @new_id, 0 otherwise.
 */
static int ata_dev_same_device(struct ata_port *ap, struct ata_device *dev,
                               unsigned int new_class, const u16 *new_id)
{
        const u16 *old_id = dev->id;
        unsigned char model[2][41], serial[2][21];
        u64 new_n_sectors;

        if (dev->class != new_class) {
                printk(KERN_INFO
                       "ata%u: dev %u class mismatch %d != %d\n",
                       ap->id, dev->devno, dev->class, new_class);
                return 0;
        }

        ata_id_c_string(old_id, model[0], ATA_ID_PROD_OFS, sizeof(model[0]));
        ata_id_c_string(new_id, model[1], ATA_ID_PROD_OFS, sizeof(model[1]));
        ata_id_c_string(old_id, serial[0], ATA_ID_SERNO_OFS, sizeof(serial[0]));
        ata_id_c_string(new_id, serial[1], ATA_ID_SERNO_OFS, sizeof(serial[1]));
        new_n_sectors = ata_id_n_sectors(new_id);

        if (strcmp(model[0], model[1])) {
                printk(KERN_INFO
                       "ata%u: dev %u model number mismatch '%s' != '%s'\n",
                       ap->id, dev->devno, model[0], model[1]);
                return 0;
        }

        if (strcmp(serial[0], serial[1])) {
                printk(KERN_INFO
                       "ata%u: dev %u serial number mismatch '%s' != '%s'\n",
                       ap->id, dev->devno, serial[0], serial[1]);
                return 0;
        }

        if (dev->class == ATA_DEV_ATA && dev->n_sectors != new_n_sectors) {
                printk(KERN_INFO
                       "ata%u: dev %u n_sectors mismatch %llu != %llu\n",
                       ap->id, dev->devno, (unsigned long long)dev->n_sectors,
                       (unsigned long long)new_n_sectors);
                return 0;
        }

        return 1;
}

/**
 *      ata_dev_revalidate - Revalidate ATA device
 *      @ap: port on which the device to revalidate resides
 *      @dev: device to revalidate
 *      @post_reset: is this revalidation after reset?
 *
 *      Re-read IDENTIFY page and make sure @dev is still attached to
 *      the port.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, negative errno otherwise
 */
int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
                       int post_reset)
{
        unsigned int class;
        u16 *id;
        int rc;

        if (!ata_dev_present(dev))
                return -ENODEV;

        class = dev->class;
        id = NULL;

        /* allocate & read ID data */
        rc = ata_dev_read_id(ap, dev, &class, post_reset, &id);
        if (rc)
                goto fail;

        /* is the device still there? */
        if (!ata_dev_same_device(ap, dev, class, id)) {
                rc = -ENODEV;
                goto fail;
        }

        kfree(dev->id);
        dev->id = id;

        /* configure device according to the new ID */
        return ata_dev_configure(ap, dev, 0);

 fail:
        printk(KERN_ERR "ata%u: dev %u revalidation failed (errno=%d)\n",
               ap->id, dev->devno, rc);
        kfree(id);
        return rc;
}

static const char * const ata_dma_blacklist [] = {
        "WDC AC11000H", NULL,
        "WDC AC22100H", NULL,
        "WDC AC32500H", NULL,
        "WDC AC33100H", NULL,
        "WDC AC31600H", NULL,
        "WDC AC32100H", "24.09P07",
        "WDC AC23200L", "21.10N21",
        "Compaq CRD-8241B",  NULL,
        "CRD-8400B", NULL,
        "CRD-8480B", NULL,
        "CRD-8482B", NULL,
        "CRD-84", NULL,
        "SanDisk SDP3B", NULL,
        "SanDisk SDP3B-64", NULL,
        "SANYO CD-ROM CRD", NULL,
        "HITACHI CDR-8", NULL,
        "HITACHI CDR-8335", NULL,
        "HITACHI CDR-8435", NULL,
        "Toshiba CD-ROM XM-6202B", NULL,
        "TOSHIBA CD-ROM XM-1702BC", NULL,
        "CD-532E-A", NULL,
        "E-IDE CD-ROM CR-840", NULL,
        "CD-ROM Drive/F5A", NULL,
        "WPI CDD-820", NULL,
        "SAMSUNG CD-ROM SC-148C", NULL,
        "SAMSUNG CD-ROM SC", NULL,
        "SanDisk SDP3B-64", NULL,
        "ATAPI CD-ROM DRIVE 40X MAXIMUM",NULL,
        "_NEC DV5800A", NULL,
        "SAMSUNG CD-ROM SN-124", "N001"
};

static int ata_strim(char *s, size_t len)
{
        len = strnlen(s, len);

        /* ATAPI specifies that empty space is blank-filled; remove blanks */
        while ((len > 0) && (s[len - 1] == ' ')) {
                len--;
                s[len] = 0;
        }
        return len;
}

static int ata_dma_blacklisted(const struct ata_device *dev)
{
        unsigned char model_num[40];
        unsigned char model_rev[16];
        unsigned int nlen, rlen;
        int i;

        ata_id_string(dev->id, model_num, ATA_ID_PROD_OFS,
                          sizeof(model_num));
        ata_id_string(dev->id, model_rev, ATA_ID_FW_REV_OFS,
                          sizeof(model_rev));
        nlen = ata_strim(model_num, sizeof(model_num));
        rlen = ata_strim(model_rev, sizeof(model_rev));

        for (i = 0; i < ARRAY_SIZE(ata_dma_blacklist); i += 2) {
                if (!strncmp(ata_dma_blacklist[i], model_num, nlen)) {
                        if (ata_dma_blacklist[i+1] == NULL)
                                return 1;
                        if (!strncmp(ata_dma_blacklist[i], model_rev, rlen))
                                return 1;
                }
        }
        return 0;
}

/**
 *      ata_dev_xfermask - Compute supported xfermask of the given device
 *      @ap: Port on which the device to compute xfermask for resides
 *      @dev: Device to compute xfermask for
 *
 *      Compute supported xfermask of @dev and store it in
 *      dev->*_mask.  This function is responsible for applying all
 *      known limits including host controller limits, device
 *      blacklist, etc...
 *
 *      LOCKING:
 *      None.
 */
static void ata_dev_xfermask(struct ata_port *ap, struct ata_device *dev)
{
        unsigned long xfer_mask;
        int i;

        xfer_mask = ata_pack_xfermask(ap->pio_mask, ap->mwdma_mask,
                                      ap->udma_mask);

        /* use port-wide xfermask for now */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *d = &ap->device[i];
                if (!ata_dev_present(d))
                        continue;
                xfer_mask &= ata_pack_xfermask(d->pio_mask, d->mwdma_mask,
                                               d->udma_mask);
                xfer_mask &= ata_id_xfermask(d->id);
                if (ata_dma_blacklisted(d))
                        xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
        }

        if (ata_dma_blacklisted(dev))
                printk(KERN_WARNING "ata%u: dev %u is on DMA blacklist, "
                       "disabling DMA\n", ap->id, dev->devno);

        ata_unpack_xfermask(xfer_mask, &dev->pio_mask, &dev->mwdma_mask,
                            &dev->udma_mask);
}

/**
 *      ata_dev_set_xfermode - Issue SET FEATURES - XFER MODE command
 *      @ap: Port associated with device @dev
 *      @dev: Device to which command will be sent
 *
 *      Issue SET FEATURES - XFER MODE command to device @dev
 *      on port @ap.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask otherwise.
 */

static unsigned int ata_dev_set_xfermode(struct ata_port *ap,
                                         struct ata_device *dev)
{
        struct ata_taskfile tf;
        unsigned int err_mask;

        /* set up set-features taskfile */
        DPRINTK("set features - xfer mode\n");

        ata_tf_init(ap, &tf, dev->devno);
        tf.command = ATA_CMD_SET_FEATURES;
        tf.feature = SETFEATURES_XFER;
        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;
        tf.nsect = dev->xfer_mode;

        err_mask = ata_exec_internal(ap, dev, &tf, DMA_NONE, NULL, 0);

        DPRINTK("EXIT, err_mask=%x\n", err_mask);
        return err_mask;
}

/**
 *      ata_dev_init_params - Issue INIT DEV PARAMS command
 *      @ap: Port associated with device @dev
 *      @dev: Device to which command will be sent
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask otherwise.
 */

static unsigned int ata_dev_init_params(struct ata_port *ap,
                                        struct ata_device *dev)
{
        struct ata_taskfile tf;
        unsigned int err_mask;
        u16 sectors = dev->id[6];
        u16 heads   = dev->id[3];

        /* Number of sectors per track 1-255. Number of heads 1-16 */
        if (sectors < 1 || sectors > 255 || heads < 1 || heads > 16)
                return 0;

        /* set up init dev params taskfile */
        DPRINTK("init dev params \n");

        ata_tf_init(ap, &tf, dev->devno);
        tf.command = ATA_CMD_INIT_DEV_PARAMS;
        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;
        tf.nsect = sectors;
        tf.device |= (heads - 1) & 0x0f; /* max head = num. of heads - 1 */

        err_mask = ata_exec_internal(ap, dev, &tf, DMA_NONE, NULL, 0);

        DPRINTK("EXIT, err_mask=%x\n", err_mask);
        return err_mask;
}

/**
 *      ata_sg_clean - Unmap DMA memory associated with command
 *      @qc: Command containing DMA memory to be released
 *
 *      Unmap all mapped DMA memory associated with this command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_sg_clean(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg = qc->__sg;
        int dir = qc->dma_dir;
        void *pad_buf = NULL;

        WARN_ON(!(qc->flags & ATA_QCFLAG_DMAMAP));
        WARN_ON(sg == NULL);

        if (qc->flags & ATA_QCFLAG_SINGLE)
                WARN_ON(qc->n_elem > 1);

        VPRINTK("unmapping %u sg elements\n", qc->n_elem);

        /* if we padded the buffer out to 32-bit bound, and data
         * xfer direction is from-device, we must copy from the
         * pad buffer back into the supplied buffer
         */
        if (qc->pad_len && !(qc->tf.flags & ATA_TFLAG_WRITE))
                pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);

        if (qc->flags & ATA_QCFLAG_SG) {
                if (qc->n_elem)
                        dma_unmap_sg(ap->dev, sg, qc->n_elem, dir);
                /* restore last sg */
                sg[qc->orig_n_elem - 1].length += qc->pad_len;
                if (pad_buf) {
                        struct scatterlist *psg = &qc->pad_sgent;
                        void *addr = kmap_atomic(psg->page, KM_IRQ0);
                        memcpy(addr + psg->offset, pad_buf, qc->pad_len);
                        kunmap_atomic(addr, KM_IRQ0);
                }
        } else {
                if (qc->n_elem)
                        dma_unmap_single(ap->dev,
                                sg_dma_address(&sg[0]), sg_dma_len(&sg[0]),
                                dir);
                /* restore sg */
                sg->length += qc->pad_len;
                if (pad_buf)
                        memcpy(qc->buf_virt + sg->length - qc->pad_len,
                               pad_buf, qc->pad_len);
        }

        qc->flags &= ~ATA_QCFLAG_DMAMAP;
        qc->__sg = NULL;
}

/**
 *      ata_fill_sg - Fill PCI IDE PRD table
 *      @qc: Metadata associated with taskfile to be transferred
 *
 *      Fill PCI IDE PRD (scatter-gather) table with segments
 *      associated with the current disk command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 */
static void ata_fill_sg(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg;
        unsigned int idx;

        WARN_ON(qc->__sg == NULL);
        WARN_ON(qc->n_elem == 0 && qc->pad_len == 0);

        idx = 0;
        ata_for_each_sg(sg, qc) {
                u32 addr, offset;
                u32 sg_len, len;

                /* determine if physical DMA addr spans 64K boundary.
                 * Note h/w doesn't support 64-bit, so we unconditionally
                 * truncate dma_addr_t to u32.
                 */
                addr = (u32) sg_dma_address(sg);
                sg_len = sg_dma_len(sg);

                while (sg_len) {
                        offset = addr & 0xffff;
                        len = sg_len;
                        if ((offset + sg_len) > 0x10000)
                                len = 0x10000 - offset;

                        ap->prd[idx].addr = cpu_to_le32(addr);
                        ap->prd[idx].flags_len = cpu_to_le32(len & 0xffff);
                        VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx, addr, len);

                        idx++;
                        sg_len -= len;
                        addr += len;
                }
        }

        if (idx)
                ap->prd[idx - 1].flags_len |= cpu_to_le32(ATA_PRD_EOT);
}
/**
 *      ata_check_atapi_dma - Check whether ATAPI DMA can be supported
 *      @qc: Metadata associated with taskfile to check
 *
 *      Allow low-level driver to filter ATA PACKET commands, returning
 *      a status indicating whether or not it is OK to use DMA for the
 *      supplied PACKET command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS: 0 when ATAPI DMA can be used
 *               nonzero otherwise
 */
int ata_check_atapi_dma(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        int rc = 0; /* Assume ATAPI DMA is OK by default */

        if (ap->ops->check_atapi_dma)
                rc = ap->ops->check_atapi_dma(qc);

        return rc;
}
/**
 *      ata_qc_prep - Prepare taskfile for submission
 *      @qc: Metadata associated with taskfile to be prepared
 *
 *      Prepare ATA taskfile for submission.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_prep(struct ata_queued_cmd *qc)
{
        if (!(qc->flags & ATA_QCFLAG_DMAMAP))
                return;

        ata_fill_sg(qc);
}

void ata_noop_qc_prep(struct ata_queued_cmd *qc) { }

/**
 *      ata_sg_init_one - Associate command with memory buffer
 *      @qc: Command to be associated
 *      @buf: Memory buffer
 *      @buflen: Length of memory buffer, in bytes.
 *
 *      Initialize the data-related elements of queued_cmd @qc
 *      to point to a single memory buffer, @buf of byte length @buflen.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_sg_init_one(struct ata_queued_cmd *qc, void *buf, unsigned int buflen)
{
        struct scatterlist *sg;

        qc->flags |= ATA_QCFLAG_SINGLE;

        memset(&qc->sgent, 0, sizeof(qc->sgent));
        qc->__sg = &qc->sgent;
        qc->n_elem = 1;
        qc->orig_n_elem = 1;
        qc->buf_virt = buf;

        sg = qc->__sg;
        sg_init_one(sg, buf, buflen);
}

/**
 *      ata_sg_init - Associate command with scatter-gather table.
 *      @qc: Command to be associated
 *      @sg: Scatter-gather table.
 *      @n_elem: Number of elements in s/g table.
 *
 *      Initialize the data-related elements of queued_cmd @qc
 *      to point to a scatter-gather table @sg, containing @n_elem
 *      elements.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,
                 unsigned int n_elem)
{
        qc->flags |= ATA_QCFLAG_SG;
        qc->__sg = sg;
        qc->n_elem = n_elem;
        qc->orig_n_elem = n_elem;
}

/**
 *      ata_sg_setup_one - DMA-map the memory buffer associated with a command.
 *      @qc: Command with memory buffer to be mapped.
 *
 *      DMA-map the memory buffer associated with queued_cmd @qc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, negative on error.
 */

static int ata_sg_setup_one(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        int dir = qc->dma_dir;
        struct scatterlist *sg = qc->__sg;
        dma_addr_t dma_address;
        int trim_sg = 0;

        /* we must lengthen transfers to end on a 32-bit boundary */
        qc->pad_len = sg->length & 3;
        if (qc->pad_len) {
                void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
                struct scatterlist *psg = &qc->pad_sgent;

                WARN_ON(qc->dev->class != ATA_DEV_ATAPI);

                memset(pad_buf, 0, ATA_DMA_PAD_SZ);

                if (qc->tf.flags & ATA_TFLAG_WRITE)
                        memcpy(pad_buf, qc->buf_virt + sg->length - qc->pad_len,
                               qc->pad_len);

                sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
                sg_dma_len(psg) = ATA_DMA_PAD_SZ;
                /* trim sg */
                sg->length -= qc->pad_len;
                if (sg->length == 0)
                        trim_sg = 1;

                DPRINTK("padding done, sg->length=%u pad_len=%u\n",
                        sg->length, qc->pad_len);
        }

        if (trim_sg) {
                qc->n_elem--;
                goto skip_map;
        }

        dma_address = dma_map_single(ap->dev, qc->buf_virt,
                                     sg->length, dir);
        if (dma_mapping_error(dma_address)) {
                /* restore sg */
                sg->length += qc->pad_len;
                return -1;
        }

        sg_dma_address(sg) = dma_address;
        sg_dma_len(sg) = sg->length;

skip_map:
        DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg),
                qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        return 0;
}

/**
 *      ata_sg_setup - DMA-map the scatter-gather table associated with a command.
 *      @qc: Command with scatter-gather table to be mapped.
 *
 *      DMA-map the scatter-gather table associated with queued_cmd @qc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, negative on error.
 *
 */

static int ata_sg_setup(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg = qc->__sg;
        struct scatterlist *lsg = &sg[qc->n_elem - 1];
        int n_elem, pre_n_elem, dir, trim_sg = 0;

        VPRINTK("ENTER, ata%u\n", ap->id);
        WARN_ON(!(qc->flags & ATA_QCFLAG_SG));

        /* we must lengthen transfers to end on a 32-bit boundary */
        qc->pad_len = lsg->length & 3;
        if (qc->pad_len) {
                void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
                struct scatterlist *psg = &qc->pad_sgent;
                unsigned int offset;

                WARN_ON(qc->dev->class != ATA_DEV_ATAPI);

                memset(pad_buf, 0, ATA_DMA_PAD_SZ);

                /*
                 * psg->page/offset are used to copy to-be-written
                 * data in this function or read data in ata_sg_clean.
                 */
                offset = lsg->offset + lsg->length - qc->pad_len;
                psg->page = nth_page(lsg->page, offset >> PAGE_SHIFT);
                psg->offset = offset_in_page(offset);

                if (qc->tf.flags & ATA_TFLAG_WRITE) {
                        void *addr = kmap_atomic(psg->page, KM_IRQ0);
                        memcpy(pad_buf, addr + psg->offset, qc->pad_len);
                        kunmap_atomic(addr, KM_IRQ0);
                }

                sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
                sg_dma_len(psg) = ATA_DMA_PAD_SZ;
                /* trim last sg */
                lsg->length -= qc->pad_len;
                if (lsg->length == 0)
                        trim_sg = 1;

                DPRINTK("padding done, sg[%d].length=%u pad_len=%u\n",
                        qc->n_elem - 1, lsg->length, qc->pad_len);
        }

        pre_n_elem = qc->n_elem;
        if (trim_sg && pre_n_elem)
                pre_n_elem--;

        if (!pre_n_elem) {
                n_elem = 0;
                goto skip_map;
        }

        dir = qc->dma_dir;
        n_elem = dma_map_sg(ap->dev, sg, pre_n_elem, dir);
        if (n_elem < 1) {
                /* restore last sg */
                lsg->length += qc->pad_len;
                return -1;
        }

        DPRINTK("%d sg elements mapped\n", n_elem);

skip_map:
        qc->n_elem = n_elem;

        return 0;
}

/**
 *      ata_poll_qc_complete - turn irq back on and finish qc
 *      @qc: Command to complete
 *      @err_mask: ATA status register content
 *
 *      LOCKING:
 *      None.  (grabs host lock)
 */

void ata_poll_qc_complete(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        unsigned long flags;

        spin_lock_irqsave(&ap->host_set->lock, flags);
        ap->flags &= ~ATA_FLAG_NOINTR;
        ata_irq_on(ap);
        ata_qc_complete(qc);
        spin_unlock_irqrestore(&ap->host_set->lock, flags);
}

/**
 *      ata_pio_poll - poll using PIO, depending on current state
 *      @ap: the target ata_port
 *
 *      LOCKING:
 *      None.  (executing in kernel thread context)
 *
 *      RETURNS:
 *      timeout value to use
 */

static unsigned long ata_pio_poll(struct ata_port *ap)
{
        struct ata_queued_cmd *qc;
        u8 status;
        unsigned int poll_state = HSM_ST_UNKNOWN;
        unsigned int reg_state = HSM_ST_UNKNOWN;

        qc = ata_qc_from_tag(ap, ap->active_tag);
        WARN_ON(qc == NULL);

        switch (ap->hsm_task_state) {
        case HSM_ST:
        case HSM_ST_POLL:
                poll_state = HSM_ST_POLL;
                reg_state = HSM_ST;
                break;
        case HSM_ST_LAST:
        case HSM_ST_LAST_POLL:
                poll_state = HSM_ST_LAST_POLL;
                reg_state = HSM_ST_LAST;
                break;
        default:
                BUG();
                break;
        }

        status = ata_chk_status(ap);
        if (status & ATA_BUSY) {
                if (time_after(jiffies, ap->pio_task_timeout)) {
                        qc->err_mask |= AC_ERR_TIMEOUT;
                        ap->hsm_task_state = HSM_ST_TMOUT;
                        return 0;
                }
                ap->hsm_task_state = poll_state;
                return ATA_SHORT_PAUSE;
        }

        ap->hsm_task_state = reg_state;
        return 0;
}

/**
 *      ata_pio_complete - check if drive is busy or idle
 *      @ap: the target ata_port
 *
 *      LOCKING:
 *      None.  (executing in kernel thread context)
 *
 *      RETURNS:
 *      Non-zero if qc completed, zero otherwise.
 */

static int ata_pio_complete (struct ata_port *ap)
{
        struct ata_queued_cmd *qc;
        u8 drv_stat;

        /*
         * This is purely heuristic.  This is a fast path.  Sometimes when
         * we enter, BSY will be cleared in a chk-status or two.  If not,
         * the drive is probably seeking or something.  Snooze for a couple
         * msecs, then chk-status again.  If still busy, fall back to
         * HSM_ST_POLL state.
         */
        drv_stat = ata_busy_wait(ap, ATA_BUSY, 10);
        if (drv_stat & ATA_BUSY) {
                msleep(2);
                drv_stat = ata_busy_wait(ap, ATA_BUSY, 10);
                if (drv_stat & ATA_BUSY) {
                        ap->hsm_task_state = HSM_ST_LAST_POLL;
                        ap->pio_task_timeout = jiffies + ATA_TMOUT_PIO;
                        return 0;
                }
        }

        qc = ata_qc_from_tag(ap, ap->active_tag);
        WARN_ON(qc == NULL);

        drv_stat = ata_wait_idle(ap);
        if (!ata_ok(drv_stat)) {
                qc->err_mask |= __ac_err_mask(drv_stat);
                ap->hsm_task_state = HSM_ST_ERR;
                return 0;
        }

        ap->hsm_task_state = HSM_ST_IDLE;

        WARN_ON(qc->err_mask);
        ata_poll_qc_complete(qc);

        /* another command may start at this point */

        return 1;
}


/**
 *      swap_buf_le16 - swap halves of 16-bit words in place
 *      @buf:  Buffer to swap
 *      @buf_words:  Number of 16-bit words in buffer.
 *
 *      Swap halves of 16-bit words if needed to convert from
 *      little-endian byte order to native cpu byte order, or
 *      vice-versa.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void swap_buf_le16(u16 *buf, unsigned int buf_words)
{
#ifdef __BIG_ENDIAN
        unsigned int i;

        for (i = 0; i < buf_words; i++)
                buf[i] = le16_to_cpu(buf[i]);
#endif /* __BIG_ENDIAN */
}

/**
 *      ata_mmio_data_xfer - Transfer data by MMIO
 *      @ap: port to read/write
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @write_data: read/write
 *
 *      Transfer data from/to the device data register by MMIO.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_mmio_data_xfer(struct ata_port *ap, unsigned char *buf,
                               unsigned int buflen, int write_data)
{
        unsigned int i;
        unsigned int words = buflen >> 1;
        u16 *buf16 = (u16 *) buf;
        void __iomem *mmio = (void __iomem *)ap->ioaddr.data_addr;

        /* Transfer multiple of 2 bytes */
        if (write_data) {
                for (i = 0; i < words; i++)
                        writew(le16_to_cpu(buf16[i]), mmio);
        } else {
                for (i = 0; i < words; i++)
                        buf16[i] = cpu_to_le16(readw(mmio));
        }

        /* Transfer trailing 1 byte, if any. */
        if (unlikely(buflen & 0x01)) {
                u16 align_buf[1] = { 0 };
                unsigned char *trailing_buf = buf + buflen - 1;

                if (write_data) {
                        memcpy(align_buf, trailing_buf, 1);
                        writew(le16_to_cpu(align_buf[0]), mmio);
                } else {
                        align_buf[0] = cpu_to_le16(readw(mmio));
                        memcpy(trailing_buf, align_buf, 1);
                }
        }
}

/**
 *      ata_pio_data_xfer - Transfer data by PIO
 *      @ap: port to read/write
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @write_data: read/write
 *
 *      Transfer data from/to the device data register by PIO.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_pio_data_xfer(struct ata_port *ap, unsigned char *buf,
                              unsigned int buflen, int write_data)
{
        unsigned int words = buflen >> 1;

        /* Transfer multiple of 2 bytes */