Merge branch 'agp-next' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied...

[linux-2.6] / drivers / ata / libata-sff.c

/*
 *  libata-sff.c - helper library for PCI IDE BMDMA
 *
 *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
 *                  Please ALWAYS copy linux-ide@vger.kernel.org
 *                  on emails.
 *
 *  Copyright 2003-2006 Red Hat, Inc.  All rights reserved.
 *  Copyright 2003-2006 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/kernel.h>
#include <linux/pci.h>
#include <linux/libata.h>
#include <linux/highmem.h>

#include "libata.h"

const struct ata_port_operations ata_sff_port_ops = {
        .inherits               = &ata_base_port_ops,

        .qc_prep                = ata_sff_qc_prep,
        .qc_issue               = ata_sff_qc_issue,
        .qc_fill_rtf            = ata_sff_qc_fill_rtf,

        .freeze                 = ata_sff_freeze,
        .thaw                   = ata_sff_thaw,
        .prereset               = ata_sff_prereset,
        .softreset              = ata_sff_softreset,
        .hardreset              = sata_sff_hardreset,
        .postreset              = ata_sff_postreset,
        .error_handler          = ata_sff_error_handler,
        .post_internal_cmd      = ata_sff_post_internal_cmd,

        .sff_dev_select         = ata_sff_dev_select,
        .sff_check_status       = ata_sff_check_status,
        .sff_tf_load            = ata_sff_tf_load,
        .sff_tf_read            = ata_sff_tf_read,
        .sff_exec_command       = ata_sff_exec_command,
        .sff_data_xfer          = ata_sff_data_xfer,
        .sff_irq_on             = ata_sff_irq_on,
        .sff_irq_clear          = ata_sff_irq_clear,

        .port_start             = ata_sff_port_start,
};

const struct ata_port_operations ata_bmdma_port_ops = {
        .inherits               = &ata_sff_port_ops,

        .mode_filter            = ata_bmdma_mode_filter,

        .bmdma_setup            = ata_bmdma_setup,
        .bmdma_start            = ata_bmdma_start,
        .bmdma_stop             = ata_bmdma_stop,
        .bmdma_status           = ata_bmdma_status,
};

/**
 *      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 lock)
 *
 */
static void ata_fill_sg(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg;
        unsigned int si, pi;

        pi = 0;
        for_each_sg(qc->sg, sg, qc->n_elem, si) {
                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[pi].addr = cpu_to_le32(addr);
                        ap->prd[pi].flags_len = cpu_to_le32(len & 0xffff);
                        VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", pi, addr, len);

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

        ap->prd[pi - 1].flags_len |= cpu_to_le32(ATA_PRD_EOT);
}

/**
 *      ata_fill_sg_dumb - 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. Perform the fill
 *      so that we avoid writing any length 64K records for
 *      controllers that don't follow the spec.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 *
 */
static void ata_fill_sg_dumb(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg;
        unsigned int si, pi;

        pi = 0;
        for_each_sg(qc->sg, sg, qc->n_elem, si) {
                u32 addr, offset;
                u32 sg_len, len, blen;

                /* 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;

                        blen = len & 0xffff;
                        ap->prd[pi].addr = cpu_to_le32(addr);
                        if (blen == 0) {
                           /* Some PATA chipsets like the CS5530 can't
                              cope with 0x0000 meaning 64K as the spec says */
                                ap->prd[pi].flags_len = cpu_to_le32(0x8000);
                                blen = 0x8000;
                                ap->prd[++pi].addr = cpu_to_le32(addr + 0x8000);
                        }
                        ap->prd[pi].flags_len = cpu_to_le32(blen);
                        VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", pi, addr, len);

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

        ap->prd[pi - 1].flags_len |= cpu_to_le32(ATA_PRD_EOT);
}

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

        ata_fill_sg(qc);
}

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

        ata_fill_sg_dumb(qc);
}

/**
 *      ata_sff_check_status - Read device status reg & clear interrupt
 *      @ap: port where the device is
 *
 *      Reads ATA taskfile status register for currently-selected device
 *      and return its value. This also clears pending interrupts
 *      from this device
 *
 *      LOCKING:
 *      Inherited from caller.
 */
u8 ata_sff_check_status(struct ata_port *ap)
{
        return ioread8(ap->ioaddr.status_addr);
}

/**
 *      ata_sff_altstatus - Read device alternate status reg
 *      @ap: port where the device is
 *
 *      Reads ATA taskfile alternate status register for
 *      currently-selected device and return its value.
 *
 *      Note: may NOT be used as the check_altstatus() entry in
 *      ata_port_operations.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
static u8 ata_sff_altstatus(struct ata_port *ap)
{
        if (ap->ops->sff_check_altstatus)
                return ap->ops->sff_check_altstatus(ap);

        return ioread8(ap->ioaddr.altstatus_addr);
}

/**
 *      ata_sff_irq_status - Check if the device is busy
 *      @ap: port where the device is
 *
 *      Determine if the port is currently busy. Uses altstatus
 *      if available in order to avoid clearing shared IRQ status
 *      when finding an IRQ source. Non ctl capable devices don't
 *      share interrupt lines fortunately for us.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
static u8 ata_sff_irq_status(struct ata_port *ap)
{
        u8 status;

        if (ap->ops->sff_check_altstatus || ap->ioaddr.altstatus_addr) {
                status = ata_sff_altstatus(ap);
                /* Not us: We are busy */
                if (status & ATA_BUSY)
                        return status;
        }
        /* Clear INTRQ latch */
        status = ap->ops->sff_check_status(ap);
        return status;
}

/**
 *      ata_sff_sync - Flush writes
 *      @ap: Port to wait for.
 *
 *      CAUTION:
 *      If we have an mmio device with no ctl and no altstatus
 *      method this will fail. No such devices are known to exist.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_sff_sync(struct ata_port *ap)
{
        if (ap->ops->sff_check_altstatus)
                ap->ops->sff_check_altstatus(ap);
        else if (ap->ioaddr.altstatus_addr)
                ioread8(ap->ioaddr.altstatus_addr);
}

/**
 *      ata_sff_pause           -       Flush writes and wait 400nS
 *      @ap: Port to pause for.
 *
 *      CAUTION:
 *      If we have an mmio device with no ctl and no altstatus
 *      method this will fail. No such devices are known to exist.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_sff_pause(struct ata_port *ap)
{
        ata_sff_sync(ap);
        ndelay(400);
}

/**
 *      ata_sff_dma_pause       -       Pause before commencing DMA
 *      @ap: Port to pause for.
 *
 *      Perform I/O fencing and ensure sufficient cycle delays occur
 *      for the HDMA1:0 transition
 */
 
void ata_sff_dma_pause(struct ata_port *ap)
{
        if (ap->ops->sff_check_altstatus || ap->ioaddr.altstatus_addr) {
                /* An altstatus read will cause the needed delay without
                   messing up the IRQ status */
                ata_sff_altstatus(ap);
                return;
        }
        /* There are no DMA controllers without ctl. BUG here to ensure
           we never violate the HDMA1:0 transition timing and risk
           corruption. */
        BUG();
}

/**
 *      ata_sff_busy_sleep - sleep until BSY clears, or timeout
 *      @ap: port containing status register to be polled
 *      @tmout_pat: impatience timeout in msecs
 *      @tmout: overall timeout in msecs
 *
 *      Sleep until ATA Status register bit BSY clears,
 *      or a timeout occurs.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_sff_busy_sleep(struct ata_port *ap,
                       unsigned long tmout_pat, unsigned long tmout)
{
        unsigned long timer_start, timeout;
        u8 status;

        status = ata_sff_busy_wait(ap, ATA_BUSY, 300);
        timer_start = jiffies;
        timeout = ata_deadline(timer_start, tmout_pat);
        while (status != 0xff && (status & ATA_BUSY) &&
               time_before(jiffies, timeout)) {
                msleep(50);
                status = ata_sff_busy_wait(ap, ATA_BUSY, 3);
        }

        if (status != 0xff && (status & ATA_BUSY))
                ata_port_printk(ap, KERN_WARNING,
                                "port is slow to respond, please be patient "
                                "(Status 0x%x)\n", status);

        timeout = ata_deadline(timer_start, tmout);
        while (status != 0xff && (status & ATA_BUSY) &&
               time_before(jiffies, timeout)) {
                msleep(50);
                status = ap->ops->sff_check_status(ap);
        }

        if (status == 0xff)
                return -ENODEV;

        if (status & ATA_BUSY) {
                ata_port_printk(ap, KERN_ERR, "port failed to respond "
                                "(%lu secs, Status 0x%x)\n",
                                DIV_ROUND_UP(tmout, 1000), status);
                return -EBUSY;
        }

        return 0;
}

static int ata_sff_check_ready(struct ata_link *link)
{
        u8 status = link->ap->ops->sff_check_status(link->ap);

        return ata_check_ready(status);
}

/**
 *      ata_sff_wait_ready - sleep until BSY clears, or timeout
 *      @link: SFF link to wait ready status for
 *      @deadline: deadline jiffies for the operation
 *
 *      Sleep until ATA Status register bit BSY clears, or timeout
 *      occurs.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_sff_wait_ready(struct ata_link *link, unsigned long deadline)
{
        return ata_wait_ready(link, deadline, ata_sff_check_ready);
}

/**
 *      ata_sff_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_sff_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;

        iowrite8(tmp, ap->ioaddr.device_addr);
        ata_sff_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_sff_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)
{
        if (ata_msg_probe(ap))
                ata_port_printk(ap, KERN_INFO, "ata_dev_select: ENTER, "
                                "device %u, wait %u\n", device, wait);

        if (wait)
                ata_wait_idle(ap);

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

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

/**
 *      ata_sff_irq_on - Enable interrupts on a port.
 *      @ap: Port on which interrupts are enabled.
 *
 *      Enable interrupts on a legacy IDE device using MMIO or PIO,
 *      wait for idle, clear any pending interrupts.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
u8 ata_sff_irq_on(struct ata_port *ap)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 tmp;

        ap->ctl &= ~ATA_NIEN;
        ap->last_ctl = ap->ctl;

        if (ioaddr->ctl_addr)
                iowrite8(ap->ctl, ioaddr->ctl_addr);
        tmp = ata_wait_idle(ap);

        ap->ops->sff_irq_clear(ap);

        return tmp;
}

/**
 *      ata_sff_irq_clear - Clear PCI IDE BMDMA interrupt.
 *      @ap: Port associated with this ATA transaction.
 *
 *      Clear interrupt and error flags in DMA status register.
 *
 *      May be used as the irq_clear() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_sff_irq_clear(struct ata_port *ap)
{
        void __iomem *mmio = ap->ioaddr.bmdma_addr;

        if (!mmio)
                return;

        iowrite8(ioread8(mmio + ATA_DMA_STATUS), mmio + ATA_DMA_STATUS);
}

/**
 *      ata_sff_tf_load - send taskfile registers to host controller
 *      @ap: Port to which output is sent
 *      @tf: ATA taskfile register set
 *
 *      Outputs ATA taskfile to standard ATA host controller.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_sff_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int is_addr = tf->flags & ATA_TFLAG_ISADDR;

        if (tf->ctl != ap->last_ctl) {
                if (ioaddr->ctl_addr)
                        iowrite8(tf->ctl, ioaddr->ctl_addr);
                ap->last_ctl = tf->ctl;
                ata_wait_idle(ap);
        }

        if (is_addr && (tf->flags & ATA_TFLAG_LBA48)) {
                WARN_ON(!ioaddr->ctl_addr);
                iowrite8(tf->hob_feature, ioaddr->feature_addr);
                iowrite8(tf->hob_nsect, ioaddr->nsect_addr);
                iowrite8(tf->hob_lbal, ioaddr->lbal_addr);
                iowrite8(tf->hob_lbam, ioaddr->lbam_addr);
                iowrite8(tf->hob_lbah, ioaddr->lbah_addr);
                VPRINTK("hob: feat 0x%X nsect 0x%X, lba 0x%X 0x%X 0x%X\n",
                        tf->hob_feature,
                        tf->hob_nsect,
                        tf->hob_lbal,
                        tf->hob_lbam,
                        tf->hob_lbah);
        }

        if (is_addr) {
                iowrite8(tf->feature, ioaddr->feature_addr);
                iowrite8(tf->nsect, ioaddr->nsect_addr);
                iowrite8(tf->lbal, ioaddr->lbal_addr);
                iowrite8(tf->lbam, ioaddr->lbam_addr);
                iowrite8(tf->lbah, ioaddr->lbah_addr);
                VPRINTK("feat 0x%X nsect 0x%X lba 0x%X 0x%X 0x%X\n",
                        tf->feature,
                        tf->nsect,
                        tf->lbal,
                        tf->lbam,
                        tf->lbah);
        }

        if (tf->flags & ATA_TFLAG_DEVICE) {
                iowrite8(tf->device, ioaddr->device_addr);
                VPRINTK("device 0x%X\n", tf->device);
        }

        ata_wait_idle(ap);
}

/**
 *      ata_sff_tf_read - input device's ATA taskfile shadow registers
 *      @ap: Port from which input is read
 *      @tf: ATA taskfile register set for storing input
 *
 *      Reads ATA taskfile registers for currently-selected device
 *      into @tf. Assumes the device has a fully SFF compliant task file
 *      layout and behaviour. If you device does not (eg has a different
 *      status method) then you will need to provide a replacement tf_read
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_sff_tf_read(struct ata_port *ap, struct ata_taskfile *tf)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;

        tf->command = ata_sff_check_status(ap);
        tf->feature = ioread8(ioaddr->error_addr);
        tf->nsect = ioread8(ioaddr->nsect_addr);
        tf->lbal = ioread8(ioaddr->lbal_addr);
        tf->lbam = ioread8(ioaddr->lbam_addr);
        tf->lbah = ioread8(ioaddr->lbah_addr);
        tf->device = ioread8(ioaddr->device_addr);

        if (tf->flags & ATA_TFLAG_LBA48) {
                if (likely(ioaddr->ctl_addr)) {
                        iowrite8(tf->ctl | ATA_HOB, ioaddr->ctl_addr);
                        tf->hob_feature = ioread8(ioaddr->error_addr);
                        tf->hob_nsect = ioread8(ioaddr->nsect_addr);
                        tf->hob_lbal = ioread8(ioaddr->lbal_addr);
                        tf->hob_lbam = ioread8(ioaddr->lbam_addr);
                        tf->hob_lbah = ioread8(ioaddr->lbah_addr);
                        iowrite8(tf->ctl, ioaddr->ctl_addr);
                        ap->last_ctl = tf->ctl;
                } else
                        WARN_ON(1);
        }
}

/**
 *      ata_sff_exec_command - issue ATA command to host controller
 *      @ap: port to which command is being issued
 *      @tf: ATA taskfile register set
 *
 *      Issues ATA command, with proper synchronization with interrupt
 *      handler / other threads.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_sff_exec_command(struct ata_port *ap, const struct ata_taskfile *tf)
{
        DPRINTK("ata%u: cmd 0x%X\n", ap->print_id, tf->command);

        iowrite8(tf->command, ap->ioaddr.command_addr);
        ata_sff_pause(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 lock)
 */
static inline void ata_tf_to_host(struct ata_port *ap,
                                  const struct ata_taskfile *tf)
{
        ap->ops->sff_tf_load(ap, tf);
        ap->ops->sff_exec_command(ap, tf);
}

/**
 *      ata_sff_data_xfer - Transfer data by PIO
 *      @dev: device to target
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @rw: read/write
 *
 *      Transfer data from/to the device data register by PIO.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 *      RETURNS:
 *      Bytes consumed.
 */
unsigned int ata_sff_data_xfer(struct ata_device *dev, unsigned char *buf,
                               unsigned int buflen, int rw)
{
        struct ata_port *ap = dev->link->ap;
        void __iomem *data_addr = ap->ioaddr.data_addr;
        unsigned int words = buflen >> 1;

        /* Transfer multiple of 2 bytes */
        if (rw == READ)
                ioread16_rep(data_addr, buf, words);
        else
                iowrite16_rep(data_addr, buf, words);

        /* Transfer trailing 1 byte, if any. */
        if (unlikely(buflen & 0x01)) {
                __le16 align_buf[1] = { 0 };
                unsigned char *trailing_buf = buf + buflen - 1;

                if (rw == READ) {
                        align_buf[0] = cpu_to_le16(ioread16(data_addr));
                        memcpy(trailing_buf, align_buf, 1);
                } else {
                        memcpy(align_buf, trailing_buf, 1);
                        iowrite16(le16_to_cpu(align_buf[0]), data_addr);
                }
                words++;
        }

        return words << 1;
}

/**
 *      ata_sff_data_xfer_noirq - Transfer data by PIO
 *      @dev: device to target
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @rw: read/write
 *
 *      Transfer data from/to the device data register by PIO. Do the
 *      transfer with interrupts disabled.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 *      RETURNS:
 *      Bytes consumed.
 */
unsigned int ata_sff_data_xfer_noirq(struct ata_device *dev, unsigned char *buf,
                                     unsigned int buflen, int rw)
{
        unsigned long flags;
        unsigned int consumed;

        local_irq_save(flags);
        consumed = ata_sff_data_xfer(dev, buf, buflen, rw);
        local_irq_restore(flags);

        return consumed;
}

/**
 *      ata_pio_sector - Transfer a sector of data.
 *      @qc: Command on going
 *
 *      Transfer qc->sect_size bytes of data from/to the ATA device.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
static void ata_pio_sector(struct ata_queued_cmd *qc)
{
        int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
        struct ata_port *ap = qc->ap;
        struct page *page;
        unsigned int offset;
        unsigned char *buf;

        if (qc->curbytes == qc->nbytes - qc->sect_size)
                ap->hsm_task_state = HSM_ST_LAST;

        page = sg_page(qc->cursg);
        offset = qc->cursg->offset + qc->cursg_ofs;

        /* get the current page and offset */
        page = nth_page(page, (offset >> PAGE_SHIFT));
        offset %= PAGE_SIZE;

        DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        if (PageHighMem(page)) {
                unsigned long flags;

                /* FIXME: use a bounce buffer */
                local_irq_save(flags);
                buf = kmap_atomic(page, KM_IRQ0);

                /* do the actual data transfer */
                ap->ops->sff_data_xfer(qc->dev, buf + offset, qc->sect_size,
                                       do_write);

                kunmap_atomic(buf, KM_IRQ0);
                local_irq_restore(flags);
        } else {
                buf = page_address(page);
                ap->ops->sff_data_xfer(qc->dev, buf + offset, qc->sect_size,
                                       do_write);
        }

        qc->curbytes += qc->sect_size;
        qc->cursg_ofs += qc->sect_size;

        if (qc->cursg_ofs == qc->cursg->length) {
                qc->cursg = sg_next(qc->cursg);
                qc->cursg_ofs = 0;
        }
}

/**
 *      ata_pio_sectors - Transfer one or many sectors.
 *      @qc: Command on going
 *
 *      Transfer one or many sectors of data from/to the
 *      ATA device for the DRQ request.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
static void ata_pio_sectors(struct ata_queued_cmd *qc)
{
        if (is_multi_taskfile(&qc->tf)) {
                /* READ/WRITE MULTIPLE */
                unsigned int nsect;

                WARN_ON(qc->dev->multi_count == 0);

                nsect = min((qc->nbytes - qc->curbytes) / qc->sect_size,
                            qc->dev->multi_count);
                while (nsect--)
                        ata_pio_sector(qc);
        } else
                ata_pio_sector(qc);

        ata_sff_sync(qc->ap); /* flush */
}

/**
 *      atapi_send_cdb - Write CDB bytes to hardware
 *      @ap: Port to which ATAPI device is attached.
 *      @qc: Taskfile currently active
 *
 *      When device has indicated its readiness to accept
 *      a CDB, this function is called.  Send the CDB.
 *
 *      LOCKING:
 *      caller.
 */
static void atapi_send_cdb(struct ata_port *ap, struct ata_queued_cmd *qc)
{
        /* send SCSI cdb */
        DPRINTK("send cdb\n");
        WARN_ON(qc->dev->cdb_len < 12);

        ap->ops->sff_data_xfer(qc->dev, qc->cdb, qc->dev->cdb_len, 1);
        ata_sff_sync(ap);
        /* FIXME: If the CDB is for DMA do we need to do the transition delay
           or is bmdma_start guaranteed to do it ? */
        switch (qc->tf.protocol) {
        case ATAPI_PROT_PIO:
                ap->hsm_task_state = HSM_ST;
                break;
        case ATAPI_PROT_NODATA:
                ap->hsm_task_state = HSM_ST_LAST;
                break;
        case ATAPI_PROT_DMA:
                ap->hsm_task_state = HSM_ST_LAST;
                /* initiate bmdma */
                ap->ops->bmdma_start(qc);
                break;
        }
}

/**
 *      __atapi_pio_bytes - Transfer data from/to the ATAPI device.
 *      @qc: Command on going
 *      @bytes: number of bytes
 *
 *      Transfer Transfer data from/to the ATAPI device.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 */
static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
{
        int rw = (qc->tf.flags & ATA_TFLAG_WRITE) ? WRITE : READ;
        struct ata_port *ap = qc->ap;
        struct ata_device *dev = qc->dev;
        struct ata_eh_info *ehi = &dev->link->eh_info;
        struct scatterlist *sg;
        struct page *page;
        unsigned char *buf;
        unsigned int offset, count, consumed;

next_sg:
        sg = qc->cursg;
        if (unlikely(!sg)) {
                ata_ehi_push_desc(ehi, "unexpected or too much trailing data "
                                  "buf=%u cur=%u bytes=%u",
                                  qc->nbytes, qc->curbytes, bytes);
                return -1;
        }

        page = sg_page(sg);
        offset = sg->offset + qc->cursg_ofs;

        /* get the current page and offset */
        page = nth_page(page, (offset >> PAGE_SHIFT));
        offset %= PAGE_SIZE;

        /* don't overrun current sg */
        count = min(sg->length - qc->cursg_ofs, bytes);

        /* don't cross page boundaries */
        count = min(count, (unsigned int)PAGE_SIZE - offset);

        DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        if (PageHighMem(page)) {
                unsigned long flags;

                /* FIXME: use bounce buffer */
                local_irq_save(flags);
                buf = kmap_atomic(page, KM_IRQ0);

                /* do the actual data transfer */
                consumed = ap->ops->sff_data_xfer(dev,  buf + offset, count, rw);

                kunmap_atomic(buf, KM_IRQ0);
                local_irq_restore(flags);
        } else {
                buf = page_address(page);
                consumed = ap->ops->sff_data_xfer(dev,  buf + offset, count, rw);
        }

        bytes -= min(bytes, consumed);
        qc->curbytes += count;
        qc->cursg_ofs += count;

        if (qc->cursg_ofs == sg->length) {
                qc->cursg = sg_next(qc->cursg);
                qc->cursg_ofs = 0;
        }

        /* consumed can be larger than count only for the last transfer */
        WARN_ON(qc->cursg && count != consumed);

        if (bytes)
                goto next_sg;
        return 0;
}

/**
 *      atapi_pio_bytes - Transfer data from/to the ATAPI device.
 *      @qc: Command on going
 *
 *      Transfer Transfer data from/to the ATAPI device.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
static void atapi_pio_bytes(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct ata_device *dev = qc->dev;
        struct ata_eh_info *ehi = &dev->link->eh_info;
        unsigned int ireason, bc_lo, bc_hi, bytes;
        int i_write, do_write = (qc->tf.flags & ATA_TFLAG_WRITE) ? 1 : 0;

        /* Abuse qc->result_tf for temp storage of intermediate TF
         * here to save some kernel stack usage.
         * For normal completion, qc->result_tf is not relevant. For
         * error, qc->result_tf is later overwritten by ata_qc_complete().
         * So, the correctness of qc->result_tf is not affected.
         */
        ap->ops->sff_tf_read(ap, &qc->result_tf);
        ireason = qc->result_tf.nsect;
        bc_lo = qc->result_tf.lbam;
        bc_hi = qc->result_tf.lbah;
        bytes = (bc_hi << 8) | bc_lo;

        /* shall be cleared to zero, indicating xfer of data */
        if (unlikely(ireason & (1 << 0)))
                goto atapi_check;

        /* make sure transfer direction matches expected */
        i_write = ((ireason & (1 << 1)) == 0) ? 1 : 0;
        if (unlikely(do_write != i_write))
                goto atapi_check;

        if (unlikely(!bytes))
                goto atapi_check;

        VPRINTK("ata%u: xfering %d bytes\n", ap->print_id, bytes);

        if (unlikely(__atapi_pio_bytes(qc, bytes)))
                goto err_out;
        ata_sff_sync(ap); /* flush */

        return;

 atapi_check:
        ata_ehi_push_desc(ehi, "ATAPI check failed (ireason=0x%x bytes=%u)",
                          ireason, bytes);
 err_out:
        qc->err_mask |= AC_ERR_HSM;
        ap->hsm_task_state = HSM_ST_ERR;
}

/**
 *      ata_hsm_ok_in_wq - Check if the qc can be handled in the workqueue.
 *      @ap: the target ata_port
 *      @qc: qc on going
 *
 *      RETURNS:
 *      1 if ok in workqueue, 0 otherwise.
 */
static inline int ata_hsm_ok_in_wq(struct ata_port *ap, struct ata_queued_cmd *qc)
{
        if (qc->tf.flags & ATA_TFLAG_POLLING)
                return 1;

        if (ap->hsm_task_state == HSM_ST_FIRST) {
                if (qc->tf.protocol == ATA_PROT_PIO &&
                    (qc->tf.flags & ATA_TFLAG_WRITE))
                    return 1;

                if (ata_is_atapi(qc->tf.protocol) &&
                    !(qc->dev->flags & ATA_DFLAG_CDB_INTR))
                        return 1;
        }

        return 0;
}

/**
 *      ata_hsm_qc_complete - finish a qc running on standard HSM
 *      @qc: Command to complete
 *      @in_wq: 1 if called from workqueue, 0 otherwise
 *
 *      Finish @qc which is running on standard HSM.
 *
 *      LOCKING:
 *      If @in_wq is zero, spin_lock_irqsave(host lock).
 *      Otherwise, none on entry and grabs host lock.
 */
static void ata_hsm_qc_complete(struct ata_queued_cmd *qc, int in_wq)
{
        struct ata_port *ap = qc->ap;
        unsigned long flags;

        if (ap->ops->error_handler) {
                if (in_wq) {
                        spin_lock_irqsave(ap->lock, flags);

                        /* EH might have kicked in while host lock is
                         * released.
                         */
                        qc = ata_qc_from_tag(ap, qc->tag);
                        if (qc) {
                                if (likely(!(qc->err_mask & AC_ERR_HSM))) {
                                        ap->ops->sff_irq_on(ap);
                                        ata_qc_complete(qc);
                                } else
                                        ata_port_freeze(ap);
                        }

                        spin_unlock_irqrestore(ap->lock, flags);
                } else {
                        if (likely(!(qc->err_mask & AC_ERR_HSM)))
                                ata_qc_complete(qc);
                        else
                                ata_port_freeze(ap);
                }
        } else {
                if (in_wq) {
                        spin_lock_irqsave(ap->lock, flags);
                        ap->ops->sff_irq_on(ap);
                        ata_qc_complete(qc);
                        spin_unlock_irqrestore(ap->lock, flags);
                } else
                        ata_qc_complete(qc);
        }
}

/**
 *      ata_sff_hsm_move - move the HSM to the next state.
 *      @ap: the target ata_port
 *      @qc: qc on going
 *      @status: current device status
 *      @in_wq: 1 if called from workqueue, 0 otherwise
 *
 *      RETURNS:
 *      1 when poll next status needed, 0 otherwise.
 */
int ata_sff_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
                     u8 status, int in_wq)
{
        struct ata_eh_info *ehi = &ap->link.eh_info;
        unsigned long flags = 0;
        int poll_next;

        WARN_ON((qc->flags & ATA_QCFLAG_ACTIVE) == 0);

        /* Make sure ata_sff_qc_issue() does not throw things
         * like DMA polling into the workqueue. Notice that
         * in_wq is not equivalent to (qc->tf.flags & ATA_TFLAG_POLLING).
         */
        WARN_ON(in_wq != ata_hsm_ok_in_wq(ap, qc));

fsm_start:
        DPRINTK("ata%u: protocol %d task_state %d (dev_stat 0x%X)\n",
                ap->print_id, qc->tf.protocol, ap->hsm_task_state, status);

        switch (ap->hsm_task_state) {
        case HSM_ST_FIRST:
                /* Send first data block or PACKET CDB */

                /* If polling, we will stay in the work queue after
                 * sending the data. Otherwise, interrupt handler
                 * takes over after sending the data.
                 */
                poll_next = (qc->tf.flags & ATA_TFLAG_POLLING);

                /* check device status */
                if (unlikely((status & ATA_DRQ) == 0)) {
                        /* handle BSY=0, DRQ=0 as error */
                        if (likely(status & (ATA_ERR | ATA_DF)))
                                /* device stops HSM for abort/error */
                                qc->err_mask |= AC_ERR_DEV;
                        else {
                                /* HSM violation. Let EH handle this */
                                ata_ehi_push_desc(ehi,
                                        "ST_FIRST: !(DRQ|ERR|DF)");
                                qc->err_mask |= AC_ERR_HSM;
                        }

                        ap->hsm_task_state = HSM_ST_ERR;
                        goto fsm_start;
                }

                /* Device should not ask for data transfer (DRQ=1)
                 * when it finds something wrong.
                 * We ignore DRQ here and stop the HSM by
                 * changing hsm_task_state to HSM_ST_ERR and
                 * let the EH abort the command or reset the device.
                 */
                if (unlikely(status & (ATA_ERR | ATA_DF))) {
                        /* Some ATAPI tape drives forget to clear the ERR bit
                         * when doing the next command (mostly request sense).
                         * We ignore ERR here to workaround and proceed sending
                         * the CDB.
                         */
                        if (!(qc->dev->horkage & ATA_HORKAGE_STUCK_ERR)) {
                                ata_ehi_push_desc(ehi, "ST_FIRST: "
                                        "DRQ=1 with device error, "
                                        "dev_stat 0x%X", status);
                                qc->err_mask |= AC_ERR_HSM;
                                ap->hsm_task_state = HSM_ST_ERR;
                                goto fsm_start;
                        }
                }

                /* Send the CDB (atapi) or the first data block (ata pio out).
                 * During the state transition, interrupt handler shouldn't
                 * be invoked before the data transfer is complete and
                 * hsm_task_state is changed. Hence, the following locking.
                 */
                if (in_wq)
                        spin_lock_irqsave(ap->lock, flags);

                if (qc->tf.protocol == ATA_PROT_PIO) {
                        /* PIO data out protocol.
                         * send first data block.
                         */

                        /* ata_pio_sectors() might change the state
                         * to HSM_ST_LAST. so, the state is changed here
                         * before ata_pio_sectors().
                         */
                        ap->hsm_task_state = HSM_ST;
                        ata_pio_sectors(qc);
                } else
                        /* send CDB */
                        atapi_send_cdb(ap, qc);

                if (in_wq)
                        spin_unlock_irqrestore(ap->lock, flags);

                /* if polling, ata_pio_task() handles the rest.
                 * otherwise, interrupt handler takes over from here.
                 */
                break;

        case HSM_ST:
                /* complete command or read/write the data register */
                if (qc->tf.protocol == ATAPI_PROT_PIO) {
                        /* ATAPI PIO protocol */
                        if ((status & ATA_DRQ) == 0) {
                                /* No more data to transfer or device error.
                                 * Device error will be tagged in HSM_ST_LAST.
                                 */
                                ap->hsm_task_state = HSM_ST_LAST;
                                goto fsm_start;
                        }

                        /* Device should not ask for data transfer (DRQ=1)
                         * when it finds something wrong.
                         * We ignore DRQ here and stop the HSM by
                         * changing hsm_task_state to HSM_ST_ERR and
                         * let the EH abort the command or reset the device.
                         */
                        if (unlikely(status & (ATA_ERR | ATA_DF))) {
                                ata_ehi_push_desc(ehi, "ST-ATAPI: "
                                        "DRQ=1 with device error, "
                                        "dev_stat 0x%X", status);
                                qc->err_mask |= AC_ERR_HSM;
                                ap->hsm_task_state = HSM_ST_ERR;
                                goto fsm_start;
                        }

                        atapi_pio_bytes(qc);

                        if (unlikely(ap->hsm_task_state == HSM_ST_ERR))
                                /* bad ireason reported by device */
                                goto fsm_start;

                } else {
                        /* ATA PIO protocol */
                        if (unlikely((status & ATA_DRQ) == 0)) {
                                /* handle BSY=0, DRQ=0 as error */
                                if (likely(status & (ATA_ERR | ATA_DF)))
                                        /* device stops HSM for abort/error */
                                        qc->err_mask |= AC_ERR_DEV;
                                else {
                                        /* HSM violation. Let EH handle this.
                                         * Phantom devices also trigger this
                                         * condition.  Mark hint.
                                         */
                                        ata_ehi_push_desc(ehi, "ST-ATA: "
                                                "DRQ=1 with device error, "
                                                "dev_stat 0x%X", status);
                                        qc->err_mask |= AC_ERR_HSM |
                                                        AC_ERR_NODEV_HINT;
                                }

                                ap->hsm_task_state = HSM_ST_ERR;
                                goto fsm_start;
                        }

                        /* For PIO reads, some devices may ask for
                         * data transfer (DRQ=1) alone with ERR=1.
                         * We respect DRQ here and transfer one
                         * block of junk data before changing the
                         * hsm_task_state to HSM_ST_ERR.
                         *
                         * For PIO writes, ERR=1 DRQ=1 doesn't make
                         * sense since the data block has been
                         * transferred to the device.
                         */
                        if (unlikely(status & (ATA_ERR | ATA_DF))) {
                                /* data might be corrputed */
                                qc->err_mask |= AC_ERR_DEV;

                                if (!(qc->tf.flags & ATA_TFLAG_WRITE)) {
                                        ata_pio_sectors(qc);
                                        status = ata_wait_idle(ap);
                                }

                                if (status & (ATA_BUSY | ATA_DRQ)) {
                                        ata_ehi_push_desc(ehi, "ST-ATA: "
                                                "BUSY|DRQ persists on ERR|DF, "
                                                "dev_stat 0x%X", status);
                                        qc->err_mask |= AC_ERR_HSM;
                                }

                                /* ata_pio_sectors() might change the
                                 * state to HSM_ST_LAST. so, the state
                                 * is changed after ata_pio_sectors().
                                 */
                                ap->hsm_task_state = HSM_ST_ERR;
                                goto fsm_start;
                        }

                        ata_pio_sectors(qc);

                        if (ap->hsm_task_state == HSM_ST_LAST &&
                            (!(qc->tf.flags & ATA_TFLAG_WRITE))) {
                                /* all data read */
                                status = ata_wait_idle(ap);
                                goto fsm_start;
                        }
                }

                poll_next = 1;
                break;

        case HSM_ST_LAST:
                if (unlikely(!ata_ok(status))) {
                        qc->err_mask |= __ac_err_mask(status);
                        ap->hsm_task_state = HSM_ST_ERR;
                        goto fsm_start;
                }

                /* no more data to transfer */
                DPRINTK("ata%u: dev %u command complete, drv_stat 0x%x\n",
                        ap->print_id, qc->dev->devno, status);

                WARN_ON(qc->err_mask & (AC_ERR_DEV | AC_ERR_HSM));

                ap->hsm_task_state = HSM_ST_IDLE;

                /* complete taskfile transaction */
                ata_hsm_qc_complete(qc, in_wq);

                poll_next = 0;
                break;

        case HSM_ST_ERR:
                ap->hsm_task_state = HSM_ST_IDLE;

                /* complete taskfile transaction */
                ata_hsm_qc_complete(qc, in_wq);

                poll_next = 0;
                break;
        default:
                poll_next = 0;
                BUG();
        }

        return poll_next;
}

void ata_pio_task(struct work_struct *work)
{
        struct ata_port *ap =
                container_of(work, struct ata_port, port_task.work);
        struct ata_queued_cmd *qc = ap->port_task_data;
        u8 status;
        int poll_next;

fsm_start:
        WARN_ON(ap->hsm_task_state == HSM_ST_IDLE);

        /*
         * 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, queue delayed work.
         */
        status = ata_sff_busy_wait(ap, ATA_BUSY, 5);
        if (status & ATA_BUSY) {
                msleep(2);
                status = ata_sff_busy_wait(ap, ATA_BUSY, 10);
                if (status & ATA_BUSY) {
                        ata_pio_queue_task(ap, qc, ATA_SHORT_PAUSE);
                        return;
                }
        }

        /* move the HSM */
        poll_next = ata_sff_hsm_move(ap, qc, status, 1);

        /* another command or interrupt handler
         * may be running at this point.
         */
        if (poll_next)
                goto fsm_start;
}

/**
 *      ata_sff_qc_issue - issue taskfile to device in proto-dependent manner
 *      @qc: command to issue to device
 *
 *      Using various libata functions and hooks, this function
 *      starts an ATA command.  ATA commands are grouped into
 *      classes called "protocols", and issuing each type of protocol
 *      is slightly different.
 *
 *      May be used as the qc_issue() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 *
 *      RETURNS:
 *      Zero on success, AC_ERR_* mask on failure
 */
unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        /* Use polling pio if the LLD doesn't handle
         * interrupt driven pio and atapi CDB interrupt.
         */
        if (ap->flags & ATA_FLAG_PIO_POLLING) {
                switch (qc->tf.protocol) {
                case ATA_PROT_PIO:
                case ATA_PROT_NODATA:
                case ATAPI_PROT_PIO:
                case ATAPI_PROT_NODATA:
                        qc->tf.flags |= ATA_TFLAG_POLLING;
                        break;
                case ATAPI_PROT_DMA:
                        if (qc->dev->flags & ATA_DFLAG_CDB_INTR)
                                /* see ata_dma_blacklisted() */
                                BUG();
                        break;
                default:
                        break;
                }
        }

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

        /* start the command */
        switch (qc->tf.protocol) {
        case ATA_PROT_NODATA:
                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_qc_set_polling(qc);

                ata_tf_to_host(ap, &qc->tf);
                ap->hsm_task_state = HSM_ST_LAST;

                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_pio_queue_task(ap, qc, 0);

                break;

        case ATA_PROT_DMA:
                WARN_ON(qc->tf.flags & ATA_TFLAG_POLLING);

                ap->ops->sff_tf_load(ap, &qc->tf);  /* load tf registers */
                ap->ops->bmdma_setup(qc);           /* set up bmdma */
                ap->ops->bmdma_start(qc);           /* initiate bmdma */
                ap->hsm_task_state = HSM_ST_LAST;
                break;

        case ATA_PROT_PIO:
                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_qc_set_polling(qc);

                ata_tf_to_host(ap, &qc->tf);

                if (qc->tf.flags & ATA_TFLAG_WRITE) {
                        /* PIO data out protocol */
                        ap->hsm_task_state = HSM_ST_FIRST;
                        ata_pio_queue_task(ap, qc, 0);

                        /* always send first data block using
                         * the ata_pio_task() codepath.
                         */
                } else {
                        /* PIO data in protocol */
                        ap->hsm_task_state = HSM_ST;

                        if (qc->tf.flags & ATA_TFLAG_POLLING)
                                ata_pio_queue_task(ap, qc, 0);

                        /* if polling, ata_pio_task() handles the rest.
                         * otherwise, interrupt handler takes over from here.
                         */
                }

                break;

        case ATAPI_PROT_PIO:
        case ATAPI_PROT_NODATA:
                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_qc_set_polling(qc);

                ata_tf_to_host(ap, &qc->tf);

                ap->hsm_task_state = HSM_ST_FIRST;

                /* send cdb by polling if no cdb interrupt */
                if ((!(qc->dev->flags & ATA_DFLAG_CDB_INTR)) ||
                    (qc->tf.flags & ATA_TFLAG_POLLING))
                        ata_pio_queue_task(ap, qc, 0);
                break;

        case ATAPI_PROT_DMA:
                WARN_ON(qc->tf.flags & ATA_TFLAG_POLLING);

                ap->ops->sff_tf_load(ap, &qc->tf);  /* load tf registers */
                ap->ops->bmdma_setup(qc);           /* set up bmdma */
                ap->hsm_task_state = HSM_ST_FIRST;

                /* send cdb by polling if no cdb interrupt */
                if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
                        ata_pio_queue_task(ap, qc, 0);
                break;

        default:
                WARN_ON(1);
                return AC_ERR_SYSTEM;
        }

        return 0;
}

/**
 *      ata_sff_qc_fill_rtf - fill result TF using ->sff_tf_read
 *      @qc: qc to fill result TF for
 *
 *      @qc is finished and result TF needs to be filled.  Fill it
 *      using ->sff_tf_read.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 *
 *      RETURNS:
 *      true indicating that result TF is successfully filled.
 */
bool ata_sff_qc_fill_rtf(struct ata_queued_cmd *qc)
{
        qc->ap->ops->sff_tf_read(qc->ap, &qc->result_tf);
        return true;
}

/**
 *      ata_sff_host_intr - Handle host interrupt for given (port, task)
 *      @ap: Port on which interrupt arrived (possibly...)
 *      @qc: Taskfile currently active in engine
 *
 *      Handle host interrupt for given queued command.  Currently,
 *      only DMA interrupts are handled.  All other commands are
 *      handled via polling with interrupts disabled (nIEN bit).
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 *
 *      RETURNS:
 *      One if interrupt was handled, zero if not (shared irq).
 */
inline unsigned int ata_sff_host_intr(struct ata_port *ap,
                                      struct ata_queued_cmd *qc)
{
        struct ata_eh_info *ehi = &ap->link.eh_info;
        u8 status, host_stat = 0;

        VPRINTK("ata%u: protocol %d task_state %d\n",
                ap->print_id, qc->tf.protocol, ap->hsm_task_state);

        /* Check whether we are expecting interrupt in this state */
        switch (ap->hsm_task_state) {
        case HSM_ST_FIRST:
                /* Some pre-ATAPI-4 devices assert INTRQ
                 * at this state when ready to receive CDB.
                 */

                /* Check the ATA_DFLAG_CDB_INTR flag is enough here.
                 * The flag was turned on only for atapi devices.  No
                 * need to check ata_is_atapi(qc->tf.protocol) again.
                 */
                if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
                        goto idle_irq;
                break;
        case HSM_ST_LAST:
                if (qc->tf.protocol == ATA_PROT_DMA ||
                    qc->tf.protocol == ATAPI_PROT_DMA) {
                        /* check status of DMA engine */
                        host_stat = ap->ops->bmdma_status(ap);
                        VPRINTK("ata%u: host_stat 0x%X\n",
                                ap->print_id, host_stat);

                        /* if it's not our irq... */
                        if (!(host_stat & ATA_DMA_INTR))
                                goto idle_irq;

                        /* before we do anything else, clear DMA-Start bit */
                        ap->ops->bmdma_stop(qc);

                        if (unlikely(host_stat & ATA_DMA_ERR)) {
                                /* error when transfering data to/from memory */
                                qc->err_mask |= AC_ERR_HOST_BUS;
                                ap->hsm_task_state = HSM_ST_ERR;
                        }
                }
                break;
        case HSM_ST:
                break;
        default:
                goto idle_irq;
        }


        /* check main status, clearing INTRQ if needed */
        status = ata_sff_irq_status(ap);
        if (status & ATA_BUSY)
                goto idle_irq;

        /* ack bmdma irq events */
        ap->ops->sff_irq_clear(ap);

        ata_sff_hsm_move(ap, qc, status, 0);

        if (unlikely(qc->err_mask) && (qc->tf.protocol == ATA_PROT_DMA ||
                                       qc->tf.protocol == ATAPI_PROT_DMA))
                ata_ehi_push_desc(ehi, "BMDMA stat 0x%x", host_stat);

        return 1;       /* irq handled */

idle_irq:
        ap->stats.idle_irq++;

#ifdef ATA_IRQ_TRAP
        if ((ap->stats.idle_irq % 1000) == 0) {
                ap->ops->sff_check_status(ap);
                ap->ops->sff_irq_clear(ap);
                ata_port_printk(ap, KERN_WARNING, "irq trap\n");
                return 1;
        }
#endif
        return 0;       /* irq not handled */
}

/**
 *      ata_sff_interrupt - Default ATA host interrupt handler
 *      @irq: irq line (unused)
 *      @dev_instance: pointer to our ata_host information structure
 *
 *      Default interrupt handler for PCI IDE devices.  Calls
 *      ata_sff_host_intr() for each port that is not disabled.
 *
 *      LOCKING:
 *      Obtains host lock during operation.
 *
 *      RETURNS:
 *      IRQ_NONE or IRQ_HANDLED.
 */
irqreturn_t ata_sff_interrupt(int irq, void *dev_instance)
{
        struct ata_host *host = dev_instance;
        unsigned int i;
        unsigned int handled = 0;
        unsigned long flags;

        /* TODO: make _irqsave conditional on x86 PCI IDE legacy mode */
        spin_lock_irqsave(&host->lock, flags);

        for (i = 0; i < host->n_ports; i++) {
                struct ata_port *ap;

                ap = host->ports[i];
                if (ap &&
                    !(ap->flags & ATA_FLAG_DISABLED)) {
                        struct ata_queued_cmd *qc;

                        qc = ata_qc_from_tag(ap, ap->link.active_tag);
                        if (qc && (!(qc->tf.flags & ATA_TFLAG_POLLING)) &&
                            (qc->flags & ATA_QCFLAG_ACTIVE))
                                handled |= ata_sff_host_intr(ap, qc);
                }
        }

        spin_unlock_irqrestore(&host->lock, flags);

        return IRQ_RETVAL(handled);
}

/**
 *      ata_sff_freeze - Freeze SFF controller port
 *      @ap: port to freeze
 *
 *      Freeze BMDMA controller port.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_sff_freeze(struct ata_port *ap)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;

        ap->ctl |= ATA_NIEN;
        ap->last_ctl = ap->ctl;

        if (ioaddr->ctl_addr)
                iowrite8(ap->ctl, ioaddr->ctl_addr);

        /* Under certain circumstances, some controllers raise IRQ on
         * ATA_NIEN manipulation.  Also, many controllers fail to mask
         * previously pending IRQ on ATA_NIEN assertion.  Clear it.
         */
        ap->ops->sff_check_status(ap);

        ap->ops->sff_irq_clear(ap);
}

/**
 *      ata_sff_thaw - Thaw SFF controller port
 *      @ap: port to thaw
 *
 *      Thaw SFF controller port.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_sff_thaw(struct ata_port *ap)
{
        /* clear & re-enable interrupts */
        ap->ops->sff_check_status(ap);
        ap->ops->sff_irq_clear(ap);
        ap->ops->sff_irq_on(ap);
}

/**
 *      ata_sff_prereset - prepare SFF link for reset
 *      @link: SFF link to be reset
 *      @deadline: deadline jiffies for the operation
 *
 *      SFF link @link is about to be reset.  Initialize it.  It first
 *      calls ata_std_prereset() and wait for !BSY if the port is
 *      being softreset.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_sff_prereset(struct ata_link *link, unsigned long deadline)
{
        struct ata_eh_context *ehc = &link->eh_context;
        int rc;

        rc = ata_std_prereset(link, deadline);
        if (rc)
                return rc;

        /* if we're about to do hardreset, nothing more to do */
        if (ehc->i.action & ATA_EH_HARDRESET)
                return 0;

        /* wait for !BSY if we don't know that no device is attached */
        if (!ata_link_offline(link)) {
                rc = ata_sff_wait_ready(link, deadline);
                if (rc && rc != -ENODEV) {
                        ata_link_printk(link, KERN_WARNING, "device not ready "
                                        "(errno=%d), forcing hardreset\n", rc);
                        ehc->i.action |= ATA_EH_HARDRESET;
                }
        }

        return 0;
}

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

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

        iowrite8(0x55, ioaddr->nsect_addr);
        iowrite8(0xaa, ioaddr->lbal_addr);

        iowrite8(0xaa, ioaddr->nsect_addr);
        iowrite8(0x55, ioaddr->lbal_addr);

        iowrite8(0x55, ioaddr->nsect_addr);
        iowrite8(0xaa, ioaddr->lbal_addr);

        nsect = ioread8(ioaddr->nsect_addr);
        lbal = ioread8(ioaddr->lbal_addr);

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

        return 0;               /* nothing found */
}

/**
 *      ata_sff_dev_classify - Parse returned ATA device signature
 *      @dev: ATA device to classify (starting at zero)
 *      @present: device seems present
 *      @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.
 */
unsigned int ata_sff_dev_classify(struct ata_device *dev, int present,
                                  u8 *r_err)
{
        struct ata_port *ap = dev->link->ap;
        struct ata_taskfile tf;
        unsigned int class;
        u8 err;

        ap->ops->sff_dev_select(ap, dev->devno);

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

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

        /* see if device passed diags: continue and warn later */
        if (err == 0)
                /* diagnostic fail : do nothing _YET_ */
                dev->horkage |= ATA_HORKAGE_DIAGNOSTIC;
        else if (err == 1)
                /* do nothing */ ;
        else if ((dev->devno == 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) {
                /* If the device failed diagnostic, it's likely to
                 * have reported incorrect device signature too.
                 * Assume ATA device if the device seems present but
                 * device signature is invalid with diagnostic
                 * failure.
                 */
                if (present && (dev->horkage & ATA_HORKAGE_DIAGNOSTIC))
                        class = ATA_DEV_ATA;
                else
                        class = ATA_DEV_NONE;
        } else if ((class == ATA_DEV_ATA) &&
                   (ap->ops->sff_check_status(ap) == 0))
                class = ATA_DEV_NONE;

        return class;
}

/**
 *      ata_sff_wait_after_reset - wait for devices to become ready after reset
 *      @link: SFF link which is just reset
 *      @devmask: mask of present devices
 *      @deadline: deadline jiffies for the operation
 *
 *      Wait devices attached to SFF @link to become ready after
 *      reset.  It contains preceding 150ms wait to avoid accessing TF
 *      status register too early.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      0 on success, -ENODEV if some or all of devices in @devmask
 *      don't seem to exist.  -errno on other errors.
 */
int ata_sff_wait_after_reset(struct ata_link *link, unsigned int devmask,
                             unsigned long deadline)
{
        struct ata_port *ap = link->ap;
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int dev0 = devmask & (1 << 0);
        unsigned int dev1 = devmask & (1 << 1);
        int rc, ret = 0;

        msleep(ATA_WAIT_AFTER_RESET);

        /* always check readiness of the master device */
        rc = ata_sff_wait_ready(link, deadline);
        /* -ENODEV means the odd clown forgot the D7 pulldown resistor
         * and TF status is 0xff, bail out on it too.
         */
        if (rc)
                return rc;

        /* if device 1 was found in ata_devchk, wait for register
         * access briefly, then wait for BSY to clear.
         */
        if (dev1) {
                int i;

                ap->ops->sff_dev_select(ap, 1);

                /* Wait for register access.  Some ATAPI devices fail
                 * to set nsect/lbal after reset, so don't waste too
                 * much time on it.  We're gonna wait for !BSY anyway.
                 */
                for (i = 0; i < 2; i++) {
                        u8 nsect, lbal;

                        nsect = ioread8(ioaddr->nsect_addr);
                        lbal = ioread8(ioaddr->lbal_addr);
                        if ((nsect == 1) && (lbal == 1))
                                break;
                        msleep(50);     /* give drive a breather */
                }

                rc = ata_sff_wait_ready(link, deadline);
                if (rc) {
                        if (rc != -ENODEV)
                                return rc;
                        ret = rc;
                }
        }

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

        return ret;
}

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

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

        /* software reset.  causes dev0 to be selected */
        iowrite8(ap->ctl, ioaddr->ctl_addr);
        udelay(20);     /* FIXME: flush */
        iowrite8(ap->ctl | ATA_SRST, ioaddr->ctl_addr);
        udelay(20);     /* FIXME: flush */
        iowrite8(ap->ctl, ioaddr->ctl_addr);

        /* wait the port to become ready */
        return ata_sff_wait_after_reset(&ap->link, devmask, deadline);
}

/**
 *      ata_sff_softreset - reset host port via ATA SRST
 *      @link: ATA link to reset
 *      @classes: resulting classes of attached devices
 *      @deadline: deadline jiffies for the operation
 *
 *      Reset host port using ATA SRST.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_sff_softreset(struct ata_link *link, unsigned int *classes,
                      unsigned long deadline)
{
        struct ata_port *ap = link->ap;
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        unsigned int devmask = 0;
        int rc;
        u8 err;

        DPRINTK("ENTER\n");

        /* 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->sff_dev_select(ap, 0);

        /* issue bus reset */
        DPRINTK("about to softreset, devmask=%x\n", devmask);
        rc = ata_bus_softreset(ap, devmask, deadline);
        /* if link is occupied, -ENODEV too is an error */
        if (rc && (rc != -ENODEV || sata_scr_valid(link))) {
                ata_link_printk(link, KERN_ERR, "SRST failed (errno=%d)\n", rc);
                return rc;
        }

        /* determine by signature whether we have ATA or ATAPI devices */
        classes[0] = ata_sff_dev_classify(&link->device[0],
                                          devmask & (1 << 0), &err);
        if (slave_possible && err != 0x81)
                classes[1] = ata_sff_dev_classify(&link->device[1],
                                                  devmask & (1 << 1), &err);

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

/**
 *      sata_sff_hardreset - reset host port via SATA phy reset
 *      @link: link to reset
 *      @class: resulting class of attached device
 *      @deadline: deadline jiffies for the operation
 *
 *      SATA phy-reset host port using DET bits of SControl register,
 *      wait for !BSY and classify the attached device.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int sata_sff_hardreset(struct ata_link *link, unsigned int *class,
                       unsigned long deadline)
{
        struct ata_eh_context *ehc = &link->eh_context;
        const unsigned long *timing = sata_ehc_deb_timing(ehc);
        bool online;
        int rc;

        rc = sata_link_hardreset(link, timing, deadline, &online,
                                 ata_sff_check_ready);
        if (online)
                *class = ata_sff_dev_classify(link->device, 1, NULL);

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

/**
 *      ata_sff_postreset - SFF postreset callback
 *      @link: the target SFF ata_link
 *      @classes: classes of attached devices
 *
 *      This function is invoked after a successful reset.  It first
 *      calls ata_std_postreset() and performs SFF specific postreset
 *      processing.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_sff_postreset(struct ata_link *link, unsigned int *classes)
{
        struct ata_port *ap = link->ap;

        ata_std_postreset(link, classes);

        /* is double-select really necessary? */
        if (classes[0] != ATA_DEV_NONE)
                ap->ops->sff_dev_select(ap, 1);
        if (classes[1] != ATA_DEV_NONE)
                ap->ops->sff_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)
                iowrite8(ap->ctl, ap->ioaddr.ctl_addr);
}

/**
 *      ata_sff_error_handler - Stock error handler for BMDMA controller
 *      @ap: port to handle error for
 *
 *      Stock error handler for SFF controller.  It can handle both
 *      PATA and SATA controllers.  Many controllers should be able to
 *      use this EH as-is or with some added handling before and
 *      after.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_sff_error_handler(struct ata_port *ap)
{
        ata_reset_fn_t softreset = ap->ops->softreset;
        ata_reset_fn_t hardreset = ap->ops->hardreset;
        struct ata_queued_cmd *qc;
        unsigned long flags;
        int thaw = 0;

        qc = __ata_qc_from_tag(ap, ap->link.active_tag);
        if (qc && !(qc->flags & ATA_QCFLAG_FAILED))
                qc = NULL;

        /* reset PIO HSM and stop DMA engine */
        spin_lock_irqsave(ap->lock, flags);

        ap->hsm_task_state = HSM_ST_IDLE;

        if (ap->ioaddr.bmdma_addr &&
            qc && (qc->tf.protocol == ATA_PROT_DMA ||
                   qc->tf.protocol == ATAPI_PROT_DMA)) {
                u8 host_stat;

                host_stat = ap->ops->bmdma_status(ap);

                /* BMDMA controllers indicate host bus error by
                 * setting DMA_ERR bit and timing out.  As it wasn't
                 * really a timeout event, adjust error mask and
                 * cancel frozen state.
                 */
                if (qc->err_mask == AC_ERR_TIMEOUT && (host_stat & ATA_DMA_ERR)) {
                        qc->err_mask = AC_ERR_HOST_BUS;
                        thaw = 1;
                }

                ap->ops->bmdma_stop(qc);
        }

        ata_sff_sync(ap);               /* FIXME: We don't need this */
        ap->ops->sff_check_status(ap);
        ap->ops->sff_irq_clear(ap);

        spin_unlock_irqrestore(ap->lock, flags);

        if (thaw)
                ata_eh_thaw_port(ap);

        /* PIO and DMA engines have been stopped, perform recovery */

        /* Ignore ata_sff_softreset if ctl isn't accessible and
         * built-in hardresets if SCR access isn't available.
         */
        if (softreset == ata_sff_softreset && !ap->ioaddr.ctl_addr)
                softreset = NULL;
        if (ata_is_builtin_hardreset(hardreset) && !sata_scr_valid(&ap->link))
                hardreset = NULL;

        ata_do_eh(ap, ap->ops->prereset, softreset, hardreset,
                  ap->ops->postreset);
}

/**
 *      ata_sff_post_internal_cmd - Stock post_internal_cmd for SFF controller
 *      @qc: internal command to clean up
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_sff_post_internal_cmd(struct ata_queued_cmd *qc)
{
        if (qc->ap->ioaddr.bmdma_addr)
                ata_bmdma_stop(qc);
}

/**
 *      ata_sff_port_start - Set port up for dma.
 *      @ap: Port to initialize
 *
 *      Called just after data structures for each port are
 *      initialized.  Allocates space for PRD table if the device
 *      is DMA capable SFF.
 *
 *      May be used as the port_start() entry in ata_port_operations.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
int ata_sff_port_start(struct ata_port *ap)
{
        if (ap->ioaddr.bmdma_addr)
                return ata_port_start(ap);
        return 0;
}

/**
 *      ata_sff_std_ports - initialize ioaddr with standard port offsets.
 *      @ioaddr: IO address structure to be initialized
 *
 *      Utility function which initializes data_addr, error_addr,
 *      feature_addr, nsect_addr, lbal_addr, lbam_addr, lbah_addr,
 *      device_addr, status_addr, and command_addr to standard offsets
 *      relative to cmd_addr.
 *
 *      Does not set ctl_addr, altstatus_addr, bmdma_addr, or scr_addr.
 */
void ata_sff_std_ports(struct ata_ioports *ioaddr)
{
        ioaddr->data_addr = ioaddr->cmd_addr + ATA_REG_DATA;
        ioaddr->error_addr = ioaddr->cmd_addr + ATA_REG_ERR;
        ioaddr->feature_addr = ioaddr->cmd_addr + ATA_REG_FEATURE;
        ioaddr->nsect_addr = ioaddr->cmd_addr + ATA_REG_NSECT;
        ioaddr->lbal_addr = ioaddr->cmd_addr + ATA_REG_LBAL;
        ioaddr->lbam_addr = ioaddr->cmd_addr + ATA_REG_LBAM;
        ioaddr->lbah_addr = ioaddr->cmd_addr + ATA_REG_LBAH;
        ioaddr->device_addr = ioaddr->cmd_addr + ATA_REG_DEVICE;
        ioaddr->status_addr = ioaddr->cmd_addr + ATA_REG_STATUS;
        ioaddr->command_addr = ioaddr->cmd_addr + ATA_REG_CMD;
}

unsigned long ata_bmdma_mode_filter(struct ata_device *adev,
                                    unsigned long xfer_mask)
{
        /* Filter out DMA modes if the device has been configured by
           the BIOS as PIO only */

        if (adev->link->ap->ioaddr.bmdma_addr == NULL)
                xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
        return xfer_mask;
}

/**
 *      ata_bmdma_setup - Set up PCI IDE BMDMA transaction
 *      @qc: Info associated with this ATA transaction.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_bmdma_setup(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        unsigned int rw = (qc->tf.flags & ATA_TFLAG_WRITE);
        u8 dmactl;

        /* load PRD table addr. */
        mb();   /* make sure PRD table writes are visible to controller */
        iowrite32(ap->prd_dma, ap->ioaddr.bmdma_addr + ATA_DMA_TABLE_OFS);

        /* specify data direction, triple-check start bit is clear */
        dmactl = ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
        dmactl &= ~(ATA_DMA_WR | ATA_DMA_START);
        if (!rw)
                dmactl |= ATA_DMA_WR;
        iowrite8(dmactl, ap->ioaddr.bmdma_addr + ATA_DMA_CMD);

        /* issue r/w command */
        ap->ops->sff_exec_command(ap, &qc->tf);
}

/**
 *      ata_bmdma_start - Start a PCI IDE BMDMA transaction
 *      @qc: Info associated with this ATA transaction.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_bmdma_start(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        u8 dmactl;

        /* start host DMA transaction */
        dmactl = ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
        iowrite8(dmactl | ATA_DMA_START, ap->ioaddr.bmdma_addr + ATA_DMA_CMD);

        /* Strictly, one may wish to issue an ioread8() here, to
         * flush the mmio write.  However, control also passes
         * to the hardware at this point, and it will interrupt
         * us when we are to resume control.  So, in effect,
         * we don't care when the mmio write flushes.
         * Further, a read of the DMA status register _immediately_
         * following the write may not be what certain flaky hardware
         * is expected, so I think it is best to not add a readb()
         * without first all the MMIO ATA cards/mobos.
         * Or maybe I'm just being paranoid.
         *
         * FIXME: The posting of this write means I/O starts are
         * unneccessarily delayed for MMIO
         */
}

/**
 *      ata_bmdma_stop - Stop PCI IDE BMDMA transfer
 *      @qc: Command we are ending DMA for
 *
 *      Clears the ATA_DMA_START flag in the dma control register
 *
 *      May be used as the bmdma_stop() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_bmdma_stop(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        void __iomem *mmio = ap->ioaddr.bmdma_addr;

        /* clear start/stop bit */
        iowrite8(ioread8(mmio + ATA_DMA_CMD) & ~ATA_DMA_START,
                 mmio + ATA_DMA_CMD);

        /* one-PIO-cycle guaranteed wait, per spec, for HDMA1:0 transition */
        ata_sff_dma_pause(ap);
}

/**
 *      ata_bmdma_status - Read PCI IDE BMDMA status
 *      @ap: Port associated with this ATA transaction.
 *
 *      Read and return BMDMA status register.
 *
 *      May be used as the bmdma_status() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
u8 ata_bmdma_status(struct ata_port *ap)
{
        return ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
}

/**
 *      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 lock.
 *
 *      SIDE EFFECTS:
 *      Sets ATA_FLAG_DISABLED if bus reset fails.
 *
 *      DEPRECATED:
 *      This function is only for drivers which still use old EH and
 *      will be removed soon.
 */
void ata_bus_reset(struct ata_port *ap)
{
        struct ata_device *device = ap->link.device;
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        u8 err;
        unsigned int dev0, dev1 = 0, devmask = 0;
        int rc;

        DPRINTK("ENTER, host %u, port %u\n", ap->print_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->sff_dev_select(ap, 0);

        /* issue bus reset */
        if (ap->flags & ATA_FLAG_SRST) {
                rc = ata_bus_softreset(ap, devmask,
                                       ata_deadline(jiffies, 40000));
                if (rc && rc != -ENODEV)
                        goto err_out;
        }

        /*
         * determine by signature whether we have ATA or ATAPI devices
         */
        device[0].class = ata_sff_dev_classify(&device[0], dev0, &err);
        if ((slave_possible) && (err != 0x81))
                device[1].class = ata_sff_dev_classify(&device[1], dev1, &err);

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

        /* if no devices were detected, disable this port */
        if ((device[0].class == ATA_DEV_NONE) &&
            (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 */
                iowrite8(ap->ctl, ioaddr->ctl_addr);
        }

        DPRINTK("EXIT\n");
        return;

err_out:
        ata_port_printk(ap, KERN_ERR, "disabling port\n");
        ata_port_disable(ap);

        DPRINTK("EXIT\n");
}

#ifdef CONFIG_PCI

/**
 *      ata_pci_bmdma_clear_simplex -   attempt to kick device out of simplex
 *      @pdev: PCI device
 *
 *      Some PCI ATA devices report simplex mode but in fact can be told to
 *      enter non simplex mode. This implements the necessary logic to
 *      perform the task on such devices. Calling it on other devices will
 *      have -undefined- behaviour.
 */
int ata_pci_bmdma_clear_simplex(struct pci_dev *pdev)
{
        unsigned long bmdma = pci_resource_start(pdev, 4);
        u8 simplex;

        if (bmdma == 0)
                return -ENOENT;

        simplex = inb(bmdma + 0x02);
        outb(simplex & 0x60, bmdma + 0x02);
        simplex = inb(bmdma + 0x02);
        if (simplex & 0x80)
                return -EOPNOTSUPP;
        return 0;
}

/**
 *      ata_pci_bmdma_init - acquire PCI BMDMA resources and init ATA host
 *      @host: target ATA host
 *
 *      Acquire PCI BMDMA resources and initialize @host accordingly.
 *
 *      LOCKING:
 *      Inherited from calling layer (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_pci_bmdma_init(struct ata_host *host)
{
        struct device *gdev = host->dev;
        struct pci_dev *pdev = to_pci_dev(gdev);
        int i, rc;

        /* No BAR4 allocation: No DMA */
        if (pci_resource_start(pdev, 4) == 0)
                return 0;

        /* TODO: If we get no DMA mask we should fall back to PIO */
        rc = pci_set_dma_mask(pdev, ATA_DMA_MASK);
        if (rc)
                return rc;
        rc = pci_set_consistent_dma_mask(pdev, ATA_DMA_MASK);
        if (rc)
                return rc;

        /* request and iomap DMA region */
        rc = pcim_iomap_regions(pdev, 1 << 4, dev_driver_string(gdev));
        if (rc) {
                dev_printk(KERN_ERR, gdev, "failed to request/iomap BAR4\n");
                return -ENOMEM;
        }
        host->iomap = pcim_iomap_table(pdev);

        for (i = 0; i < 2; i++) {
                struct ata_port *ap = host->ports[i];
                void __iomem *bmdma = host->iomap[4] + 8 * i;

                if (ata_port_is_dummy(ap))
                        continue;

                ap->ioaddr.bmdma_addr = bmdma;
                if ((!(ap->flags & ATA_FLAG_IGN_SIMPLEX)) &&
                    (ioread8(bmdma + 2) & 0x80))
                        host->flags |= ATA_HOST_SIMPLEX;

                ata_port_desc(ap, "bmdma 0x%llx",
                        (unsigned long long)pci_resource_start(pdev, 4) + 8 * i);
        }

        return 0;
}

static int ata_resources_present(struct pci_dev *pdev, int port)
{
        int i;

        /* Check the PCI resources for this channel are enabled */
        port = port * 2;
        for (i = 0; i < 2; i ++) {
                if (pci_resource_start(pdev, port + i) == 0 ||
                    pci_resource_len(pdev, port + i) == 0)
                        return 0;
        }
        return 1;
}

/**
 *      ata_pci_sff_init_host - acquire native PCI ATA resources and init host
 *      @host: target ATA host
 *
 *      Acquire native PCI ATA resources for @host and initialize the
 *      first two ports of @host accordingly.  Ports marked dummy are
 *      skipped and allocation failure makes the port dummy.
 *
 *      Note that native PCI resources are valid even for legacy hosts
 *      as we fix up pdev resources array early in boot, so this
 *      function can be used for both native and legacy SFF hosts.
 *
 *      LOCKING:
 *      Inherited from calling layer (may sleep).
 *
 *      RETURNS:
 *      0 if at least one port is initialized, -ENODEV if no port is
 *      available.
 */
int ata_pci_sff_init_host(struct ata_host *host)
{
        struct device *gdev = host->dev;
        struct pci_dev *pdev = to_pci_dev(gdev);
        unsigned int mask = 0;
        int i, rc;

        /* request, iomap BARs and init port addresses accordingly */
        for (i = 0; i < 2; i++) {
                struct ata_port *ap = host->ports[i];
                int base = i * 2;
                void __iomem * const *iomap;

                if (ata_port_is_dummy(ap))
                        continue;

                /* Discard disabled ports.  Some controllers show
                 * their unused channels this way.  Disabled ports are
                 * made dummy.
                 */
                if (!ata_resources_present(pdev, i)) {
                        ap->ops = &ata_dummy_port_ops;
                        continue;
                }

                rc = pcim_iomap_regions(pdev, 0x3 << base,
                                        dev_driver_string(gdev));
                if (rc) {
                        dev_printk(KERN_WARNING, gdev,
                                   "failed to request/iomap BARs for port %d "
                                   "(errno=%d)\n", i, rc);
                        if (rc == -EBUSY)
                                pcim_pin_device(pdev);
                        ap->ops = &ata_dummy_port_ops;
                        continue;
                }
                host->iomap = iomap = pcim_iomap_table(pdev);

                ap->ioaddr.cmd_addr = iomap[base];
                ap->ioaddr.altstatus_addr =
                ap->ioaddr.ctl_addr = (void __iomem *)
                        ((unsigned long)iomap[base + 1] | ATA_PCI_CTL_OFS);
                ata_sff_std_ports(&ap->ioaddr);

                ata_port_desc(ap, "cmd 0x%llx ctl 0x%llx",
                        (unsigned long long)pci_resource_start(pdev, base),
                        (unsigned long long)pci_resource_start(pdev, base + 1));

                mask |= 1 << i;
        }

        if (!mask) {
                dev_printk(KERN_ERR, gdev, "no available native port\n");
                return -ENODEV;
        }

        return 0;
}

/**
 *      ata_pci_sff_prepare_host - helper to prepare native PCI ATA host
 *      @pdev: target PCI device
 *      @ppi: array of port_info, must be enough for two ports
 *      @r_host: out argument for the initialized ATA host
 *
 *      Helper to allocate ATA host for @pdev, acquire all native PCI
 *      resources and initialize it accordingly in one go.
 *
 *      LOCKING:
 *      Inherited from calling layer (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_pci_sff_prepare_host(struct pci_dev *pdev,
                             const struct ata_port_info * const * ppi,
                             struct ata_host **r_host)
{
        struct ata_host *host;
        int rc;

        if (!devres_open_group(&pdev->dev, NULL, GFP_KERNEL))
                return -ENOMEM;

        host = ata_host_alloc_pinfo(&pdev->dev, ppi, 2);
        if (!host) {
                dev_printk(KERN_ERR, &pdev->dev,
                           "failed to allocate ATA host\n");
                rc = -ENOMEM;
                goto err_out;
        }

        rc = ata_pci_sff_init_host(host);
        if (rc)
                goto err_out;

        /* init DMA related stuff */
        rc = ata_pci_bmdma_init(host);
        if (rc)
                goto err_bmdma;

        devres_remove_group(&pdev->dev, NULL);
        *r_host = host;
        return 0;

 err_bmdma:
        /* This is necessary because PCI and iomap resources are
         * merged and releasing the top group won't release the
         * acquired resources if some of those have been acquired
         * before entering this function.
         */
        pcim_iounmap_regions(pdev, 0xf);
 err_out:
        devres_release_group(&pdev->dev, NULL);
        return rc;
}

/**
 *      ata_pci_sff_activate_host - start SFF host, request IRQ and register it
 *      @host: target SFF ATA host
 *      @irq_handler: irq_handler used when requesting IRQ(s)
 *      @sht: scsi_host_template to use when registering the host
 *
 *      This is the counterpart of ata_host_activate() for SFF ATA
 *      hosts.  This separate helper is necessary because SFF hosts
 *      use two separate interrupts in legacy mode.
 *
 *      LOCKING:
 *      Inherited from calling layer (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_pci_sff_activate_host(struct ata_host *host,
                              irq_handler_t irq_handler,
                              struct scsi_host_template *sht)
{
        struct device *dev = host->dev;
        struct pci_dev *pdev = to_pci_dev(dev);
        const char *drv_name = dev_driver_string(host->dev);
        int legacy_mode = 0, rc;

        rc = ata_host_start(host);
        if (rc)
                return rc;

        if ((pdev->class >> 8) == PCI_CLASS_STORAGE_IDE) {
                u8 tmp8, mask;

                /* TODO: What if one channel is in native mode ... */
                pci_read_config_byte(pdev, PCI_CLASS_PROG, &tmp8);
                mask = (1 << 2) | (1 << 0);
                if ((tmp8 & mask) != mask)
                        legacy_mode = 1;
#if defined(CONFIG_NO_ATA_LEGACY)
                /* Some platforms with PCI limits cannot address compat
                   port space. In that case we punt if their firmware has
                   left a device in compatibility mode */
                if (legacy_mode) {
                        printk(KERN_ERR "ata: Compatibility mode ATA is not supported on this platform, skipping.\n");
                        return -EOPNOTSUPP;
                }
#endif
        }

        if (!devres_open_group(dev, NULL, GFP_KERNEL))
                return -ENOMEM;

        if (!legacy_mode && pdev->irq) {
                rc = devm_request_irq(dev, pdev->irq, irq_handler,
                                      IRQF_SHARED, drv_name, host);
                if (rc)
                        goto out;

                ata_port_desc(host->ports[0], "irq %d", pdev->irq);
                ata_port_desc(host->ports[1], "irq %d", pdev->irq);
        } else if (legacy_mode) {
                if (!ata_port_is_dummy(host->ports[0])) {
                        rc = devm_request_irq(dev, ATA_PRIMARY_IRQ(pdev),
                                              irq_handler, IRQF_SHARED,
                                              drv_name, host);
                        if (rc)
                                goto out;

                        ata_port_desc(host->ports[0], "irq %d",
                                      ATA_PRIMARY_IRQ(pdev));
                }

                if (!ata_port_is_dummy(host->ports[1])) {
                        rc = devm_request_irq(dev, ATA_SECONDARY_IRQ(pdev),
                                              irq_handler, IRQF_SHARED,
                                              drv_name, host);
                        if (rc)
                                goto out;

                        ata_port_desc(host->ports[1], "irq %d",
                                      ATA_SECONDARY_IRQ(pdev));
                }
        }

        rc = ata_host_register(host, sht);
 out:
        if (rc == 0)
                devres_remove_group(dev, NULL);
        else
                devres_release_group(dev, NULL);

        return rc;
}

/**
 *      ata_pci_sff_init_one - Initialize/register PCI IDE host controller
 *      @pdev: Controller to be initialized
 *      @ppi: array of port_info, must be enough for two ports
 *      @sht: scsi_host_template to use when registering the host
 *      @host_priv: host private_data
 *
 *      This is a helper function which can be called from a driver's
 *      xxx_init_one() probe function if the hardware uses traditional
 *      IDE taskfile registers.
 *
 *      This function calls pci_enable_device(), reserves its register
 *      regions, sets the dma mask, enables bus master mode, and calls
 *      ata_device_add()
 *
 *      ASSUMPTION:
 *      Nobody makes a single channel controller that appears solely as
 *      the secondary legacy port on PCI.
 *
 *      LOCKING:
 *      Inherited from PCI layer (may sleep).
 *
 *      RETURNS:
 *      Zero on success, negative on errno-based value on error.
 */
int ata_pci_sff_init_one(struct pci_dev *pdev,
                         const struct ata_port_info * const * ppi,
                         struct scsi_host_template *sht, void *host_priv)
{
        struct device *dev = &pdev->dev;
        const struct ata_port_info *pi = NULL;
        struct ata_host *host = NULL;
        int i, rc;

        DPRINTK("ENTER\n");

        /* look up the first valid port_info */
        for (i = 0; i < 2 && ppi[i]; i++) {
                if (ppi[i]->port_ops != &ata_dummy_port_ops) {
                        pi = ppi[i];
                        break;
                }
        }

        if (!pi) {
                dev_printk(KERN_ERR, &pdev->dev,
                           "no valid port_info specified\n");
                return -EINVAL;
        }

        if (!devres_open_group(dev, NULL, GFP_KERNEL))
                return -ENOMEM;

        rc = pcim_enable_device(pdev);
        if (rc)
                goto out;

        /* prepare and activate SFF host */
        rc = ata_pci_sff_prepare_host(pdev, ppi, &host);
        if (rc)
                goto out;
        host->private_data = host_priv;

        pci_set_master(pdev);
        rc = ata_pci_sff_activate_host(host, ata_sff_interrupt, sht);
 out:
        if (rc == 0)
                devres_remove_group(&pdev->dev, NULL);
        else
                devres_release_group(&pdev->dev, NULL);

        return rc;
}

#endif /* CONFIG_PCI */

EXPORT_SYMBOL_GPL(ata_sff_port_ops);
EXPORT_SYMBOL_GPL(ata_bmdma_port_ops);
EXPORT_SYMBOL_GPL(ata_sff_qc_prep);
EXPORT_SYMBOL_GPL(ata_sff_dumb_qc_prep);
EXPORT_SYMBOL_GPL(ata_sff_dev_select);
EXPORT_SYMBOL_GPL(ata_sff_check_status);
EXPORT_SYMBOL_GPL(ata_sff_dma_pause);
EXPORT_SYMBOL_GPL(ata_sff_pause);
EXPORT_SYMBOL_GPL(ata_sff_busy_sleep);
EXPORT_SYMBOL_GPL(ata_sff_wait_ready);
EXPORT_SYMBOL_GPL(ata_sff_tf_load);
EXPORT_SYMBOL_GPL(ata_sff_tf_read);
EXPORT_SYMBOL_GPL(ata_sff_exec_command);
EXPORT_SYMBOL_GPL(ata_sff_data_xfer);
EXPORT_SYMBOL_GPL(ata_sff_data_xfer_noirq);
EXPORT_SYMBOL_GPL(ata_sff_irq_on);
EXPORT_SYMBOL_GPL(ata_sff_irq_clear);
EXPORT_SYMBOL_GPL(ata_sff_hsm_move);
EXPORT_SYMBOL_GPL(ata_sff_qc_issue);
EXPORT_SYMBOL_GPL(ata_sff_qc_fill_rtf);
EXPORT_SYMBOL_GPL(ata_sff_host_intr);
EXPORT_SYMBOL_GPL(ata_sff_interrupt);
EXPORT_SYMBOL_GPL(ata_sff_freeze);
EXPORT_SYMBOL_GPL(ata_sff_thaw);
EXPORT_SYMBOL_GPL(ata_sff_prereset);
EXPORT_SYMBOL_GPL(ata_sff_dev_classify);
EXPORT_SYMBOL_GPL(ata_sff_wait_after_reset);
EXPORT_SYMBOL_GPL(ata_sff_softreset);
EXPORT_SYMBOL_GPL(sata_sff_hardreset);
EXPORT_SYMBOL_GPL(ata_sff_postreset);
EXPORT_SYMBOL_GPL(ata_sff_error_handler);
EXPORT_SYMBOL_GPL(ata_sff_post_internal_cmd);
EXPORT_SYMBOL_GPL(ata_sff_port_start);
EXPORT_SYMBOL_GPL(ata_sff_std_ports);
EXPORT_SYMBOL_GPL(ata_bmdma_mode_filter);
EXPORT_SYMBOL_GPL(ata_bmdma_setup);
EXPORT_SYMBOL_GPL(ata_bmdma_start);
EXPORT_SYMBOL_GPL(ata_bmdma_stop);
EXPORT_SYMBOL_GPL(ata_bmdma_status);
EXPORT_SYMBOL_GPL(ata_bus_reset);
#ifdef CONFIG_PCI
EXPORT_SYMBOL_GPL(ata_pci_bmdma_clear_simplex);
EXPORT_SYMBOL_GPL(ata_pci_bmdma_init);
EXPORT_SYMBOL_GPL(ata_pci_sff_init_host);
EXPORT_SYMBOL_GPL(ata_pci_sff_prepare_host);
EXPORT_SYMBOL_GPL(ata_pci_sff_activate_host);
EXPORT_SYMBOL_GPL(ata_pci_sff_init_one);
#endif /* CONFIG_PCI */