/*
 *  linux/drivers/ide/ide-dma.c         Version 4.10    June 9, 2000
 *
 *  Copyright (c) 1999-2000     Andre Hedrick <andre@linux-ide.org>
 *  May be copied or modified under the terms of the GNU General Public License
 */

/*
 *  Special Thanks to Mark for his Six years of work.
 *
 *  Copyright (c) 1995-1998  Mark Lord
 *  May be copied or modified under the terms of the GNU General Public License
 */

/*
 * This module provides support for the bus-master IDE DMA functions
 * of various PCI chipsets, including the Intel PIIX (i82371FB for
 * the 430 FX chipset), the PIIX3 (i82371SB for the 430 HX/VX and 
 * 440 chipsets), and the PIIX4 (i82371AB for the 430 TX chipset)
 * ("PIIX" stands for "PCI ISA IDE Xcellerator").
 *
 * Pretty much the same code works for other IDE PCI bus-mastering chipsets.
 *
 * DMA is supported for all IDE devices (disk drives, cdroms, tapes, floppies).
 *
 * By default, DMA support is prepared for use, but is currently enabled only
 * for drives which already have DMA enabled (UltraDMA or mode 2 multi/single),
 * or which are recognized as "good" (see table below).  Drives with only mode0
 * or mode1 (multi/single) DMA should also work with this chipset/driver
 * (eg. MC2112A) but are not enabled by default.
 *
 * Use "hdparm -i" to view modes supported by a given drive.
 *
 * The hdparm-3.5 (or later) utility can be used for manually enabling/disabling
 * DMA support, but must be (re-)compiled against this kernel version or later.
 *
 * To enable DMA, use "hdparm -d1 /dev/hd?" on a per-drive basis after booting.
 * If problems arise, ide.c will disable DMA operation after a few retries.
 * This error recovery mechanism works and has been extremely well exercised.
 *
 * IDE drives, depending on their vintage, may support several different modes
 * of DMA operation.  The boot-time modes are indicated with a "*" in
 * the "hdparm -i" listing, and can be changed with *knowledgeable* use of
 * the "hdparm -X" feature.  There is seldom a need to do this, as drives
 * normally power-up with their "best" PIO/DMA modes enabled.
 *
 * Testing has been done with a rather extensive number of drives,
 * with Quantum & Western Digital models generally outperforming the pack,
 * and Fujitsu & Conner (and some Seagate which are really Conner) drives
 * showing more lackluster throughput.
 *
 * Keep an eye on /var/adm/messages for "DMA disabled" messages.
 *
 * Some people have reported trouble with Intel Zappa motherboards.
 * This can be fixed by upgrading the AMI BIOS to version 1.00.04.BS0,
 * available from ftp://ftp.intel.com/pub/bios/10004bs0.exe
 * (thanks to Glen Morrell <glen@spin.Stanford.edu> for researching this).
 *
 * Thanks to "Christopher J. Reimer" <reimer@doe.carleton.ca> for
 * fixing the problem with the BIOS on some Acer motherboards.
 *
 * Thanks to "Benoit Poulot-Cazajous" <poulot@chorus.fr> for testing
 * "TX" chipset compatibility and for providing patches for the "TX" chipset.
 *
 * Thanks to Christian Brunner <chb@muc.de> for taking a good first crack
 * at generic DMA -- his patches were referred to when preparing this code.
 *
 * Most importantly, thanks to Robert Bringman <rob@mars.trion.com>
 * for supplying a Promise UDMA board & WD UDMA drive for this work!
 *
 * And, yes, Intel Zappa boards really *do* use both PIIX IDE ports.
 *
 * ATA-66/100 and recovery functions, I forgot the rest......
 *
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/ide.h>
#include <linux/delay.h>
#include <linux/scatterlist.h>

#include <asm/io.h>
#include <asm/irq.h>

static const struct drive_list_entry drive_whitelist [] = {

        { "Micropolis 2112A"    ,       NULL            },
        { "CONNER CTMA 4000"    ,       NULL            },
        { "CONNER CTT8000-A"    ,       NULL            },
        { "ST34342A"            ,       NULL            },
        { NULL                  ,       NULL            }
};

static const struct drive_list_entry drive_blacklist [] = {

        { "WDC AC11000H"        ,       NULL            },
        { "WDC AC22100H"        ,       NULL            },
        { "WDC AC32500H"        ,       NULL            },
        { "WDC AC33100H"        ,       NULL            },
        { "WDC AC31600H"        ,       NULL            },
        { "WDC AC32100H"        ,       "24.09P07"      },
        { "WDC AC23200L"        ,       "21.10N21"      },
        { "Compaq CRD-8241B"    ,       NULL            },
        { "CRD-8400B"           ,       NULL            },
        { "CRD-8480B",                  NULL            },
        { "CRD-8482B",                  NULL            },
        { "CRD-84"              ,       NULL            },
        { "SanDisk SDP3B"       ,       NULL            },
        { "SanDisk SDP3B-64"    ,       NULL            },
        { "SANYO CD-ROM CRD"    ,       NULL            },
        { "HITACHI CDR-8"       ,       NULL            },
        { "HITACHI CDR-8335"    ,       NULL            },
        { "HITACHI CDR-8435"    ,       NULL            },
        { "Toshiba CD-ROM XM-6202B"     ,       NULL            },
        { "TOSHIBA CD-ROM XM-1702BC",   NULL            },
        { "CD-532E-A"           ,       NULL            },
        { "E-IDE CD-ROM CR-840",        NULL            },
        { "CD-ROM Drive/F5A",   NULL            },
        { "WPI CDD-820",                NULL            },
        { "SAMSUNG CD-ROM SC-148C",     NULL            },
        { "SAMSUNG CD-ROM SC",  NULL            },
        { "ATAPI CD-ROM DRIVE 40X MAXIMUM",     NULL            },
        { "_NEC DV5800A",               NULL            },
        { "SAMSUNG CD-ROM SN-124",      "N001" },
        { "Seagate STT20000A",          NULL  },
        { "CD-ROM CDR_U200",            "1.09" },
        { NULL                  ,       NULL            }

};

/**
 *      ide_dma_intr    -       IDE DMA interrupt handler
 *      @drive: the drive the interrupt is for
 *
 *      Handle an interrupt completing a read/write DMA transfer on an 
 *      IDE device
 */
 
ide_startstop_t ide_dma_intr (ide_drive_t *drive)
{
        u8 stat = 0, dma_stat = 0;

        dma_stat = HWIF(drive)->ide_dma_end(drive);
        stat = HWIF(drive)->INB(IDE_STATUS_REG);        /* get drive status */
        if (OK_STAT(stat,DRIVE_READY,drive->bad_wstat|DRQ_STAT)) {
                if (!dma_stat) {
                        struct request *rq = HWGROUP(drive)->rq;

                        if (rq->rq_disk) {
                                ide_driver_t *drv;

                                drv = *(ide_driver_t **)rq->rq_disk->private_data;
                                drv->end_request(drive, 1, rq->nr_sectors);
                        } else
                                ide_end_request(drive, 1, rq->nr_sectors);
                        return ide_stopped;
                }
                printk(KERN_ERR "%s: dma_intr: bad DMA status (dma_stat=%x)\n", 
                       drive->name, dma_stat);
        }
        return ide_error(drive, "dma_intr", stat);
}

EXPORT_SYMBOL_GPL(ide_dma_intr);

static int ide_dma_good_drive(ide_drive_t *drive)
{
        return ide_in_drive_list(drive->id, drive_whitelist);
}

#ifdef CONFIG_BLK_DEV_IDEDMA_PCI
/**
 *      ide_build_sglist        -       map IDE scatter gather for DMA I/O
 *      @drive: the drive to build the DMA table for
 *      @rq: the request holding the sg list
 *
 *      Perform the PCI mapping magic necessary to access the source or
 *      target buffers of a request via PCI DMA. The lower layers of the
 *      kernel provide the necessary cache management so that we can
 *      operate in a portable fashion
 */

int ide_build_sglist(ide_drive_t *drive, struct request *rq)
{
        ide_hwif_t *hwif = HWIF(drive);
        struct scatterlist *sg = hwif->sg_table;

        BUG_ON((rq->cmd_type == REQ_TYPE_ATA_TASKFILE) && rq->nr_sectors > 256);

        ide_map_sg(drive, rq);

        if (rq_data_dir(rq) == READ)
                hwif->sg_dma_direction = PCI_DMA_FROMDEVICE;
        else
                hwif->sg_dma_direction = PCI_DMA_TODEVICE;

        return pci_map_sg(hwif->pci_dev, sg, hwif->sg_nents, hwif->sg_dma_direction);
}

EXPORT_SYMBOL_GPL(ide_build_sglist);

/**
 *      ide_build_dmatable      -       build IDE DMA table
 *
 *      ide_build_dmatable() prepares a dma request. We map the command
 *      to get the pci bus addresses of the buffers and then build up
 *      the PRD table that the IDE layer wants to be fed. The code
 *      knows about the 64K wrap bug in the CS5530.
 *
 *      Returns the number of built PRD entries if all went okay,
 *      returns 0 otherwise.
 *
 *      May also be invoked from trm290.c
 */
 
int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
{
        ide_hwif_t *hwif        = HWIF(drive);
        unsigned int *table     = hwif->dmatable_cpu;
        unsigned int is_trm290  = (hwif->chipset == ide_trm290) ? 1 : 0;
        unsigned int count = 0;
        int i;
        struct scatterlist *sg;

        hwif->sg_nents = i = ide_build_sglist(drive, rq);

        if (!i)
                return 0;

        sg = hwif->sg_table;
        while (i) {
                u32 cur_addr;
                u32 cur_len;

                cur_addr = sg_dma_address(sg);
                cur_len = sg_dma_len(sg);

                /*
                 * Fill in the dma table, without crossing any 64kB boundaries.
                 * Most hardware requires 16-bit alignment of all blocks,
                 * but the trm290 requires 32-bit alignment.
                 */

                while (cur_len) {
                        if (count++ >= PRD_ENTRIES) {
                                printk(KERN_ERR "%s: DMA table too small\n", drive->name);
                                goto use_pio_instead;
                        } else {
                                u32 xcount, bcount = 0x10000 - (cur_addr & 0xffff);

                                if (bcount > cur_len)
                                        bcount = cur_len;
                                *table++ = cpu_to_le32(cur_addr);
                                xcount = bcount & 0xffff;
                                if (is_trm290)
                                        xcount = ((xcount >> 2) - 1) << 16;
                                if (xcount == 0x0000) {
        /* 
         * Most chipsets correctly interpret a length of 0x0000 as 64KB,
         * but at least one (e.g. CS5530) misinterprets it as zero (!).
         * So here we break the 64KB entry into two 32KB entries instead.
         */
                                        if (count++ >= PRD_ENTRIES) {
                                                printk(KERN_ERR "%s: DMA table too small\n", drive->name);
                                                goto use_pio_instead;
                                        }
                                        *table++ = cpu_to_le32(0x8000);
                                        *table++ = cpu_to_le32(cur_addr + 0x8000);
                                        xcount = 0x8000;
                                }
                                *table++ = cpu_to_le32(xcount);
                                cur_addr += bcount;
                                cur_len -= bcount;
                        }
                }

                sg = sg_next(sg);
                i--;
        }

        if (count) {
                if (!is_trm290)
                        *--table |= cpu_to_le32(0x80000000);
                return count;
        }
        printk(KERN_ERR "%s: empty DMA table?\n", drive->name);
use_pio_instead:
        pci_unmap_sg(hwif->pci_dev,
                     hwif->sg_table,
                     hwif->sg_nents,
                     hwif->sg_dma_direction);
        return 0; /* revert to PIO for this request */
}

EXPORT_SYMBOL_GPL(ide_build_dmatable);

/**
 *      ide_destroy_dmatable    -       clean up DMA mapping
 *      @drive: The drive to unmap
 *
 *      Teardown mappings after DMA has completed. This must be called
 *      after the completion of each use of ide_build_dmatable and before
 *      the next use of ide_build_dmatable. Failure to do so will cause
 *      an oops as only one mapping can be live for each target at a given
 *      time.
 */
 
void ide_destroy_dmatable (ide_drive_t *drive)
{
        struct pci_dev *dev = HWIF(drive)->pci_dev;
        struct scatterlist *sg = HWIF(drive)->sg_table;
        int nents = HWIF(drive)->sg_nents;

        pci_unmap_sg(dev, sg, nents, HWIF(drive)->sg_dma_direction);
}

EXPORT_SYMBOL_GPL(ide_destroy_dmatable);

/**
 *      config_drive_for_dma    -       attempt to activate IDE DMA
 *      @drive: the drive to place in DMA mode
 *
 *      If the drive supports at least mode 2 DMA or UDMA of any kind
 *      then attempt to place it into DMA mode. Drives that are known to
 *      support DMA but predate the DMA properties or that are known
 *      to have DMA handling bugs are also set up appropriately based
 *      on the good/bad drive lists.
 */
 
static int config_drive_for_dma (ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        struct hd_driveid *id = drive->id;

        if (drive->media != ide_disk) {
                if (hwif->host_flags & IDE_HFLAG_NO_ATAPI_DMA)
                        return 0;
        }

        /*
         * Enable DMA on any drive that has
         * UltraDMA (mode 0/1/2/3/4/5/6) enabled
         */
        if ((id->field_valid & 4) && ((id->dma_ultra >> 8) & 0x7f))
                return 1;

        /*
         * Enable DMA on any drive that has mode2 DMA
         * (multi or single) enabled
         */
        if (id->field_valid & 2)        /* regular DMA */
                if ((id->dma_mword & 0x404) == 0x404 ||
                    (id->dma_1word & 0x404) == 0x404)
                        return 1;

        /* Consult the list of known "good" drives */
        if (ide_dma_good_drive(drive))
                return 1;

        return 0;
}

/**
 *      dma_timer_expiry        -       handle a DMA timeout
 *      @drive: Drive that timed out
 *
 *      An IDE DMA transfer timed out. In the event of an error we ask
 *      the driver to resolve the problem, if a DMA transfer is still
 *      in progress we continue to wait (arguably we need to add a 
 *      secondary 'I don't care what the drive thinks' timeout here)
 *      Finally if we have an interrupt we let it complete the I/O.
 *      But only one time - we clear expiry and if it's still not
 *      completed after WAIT_CMD, we error and retry in PIO.
 *      This can occur if an interrupt is lost or due to hang or bugs.
 */
 
static int dma_timer_expiry (ide_drive_t *drive)
{
        ide_hwif_t *hwif        = HWIF(drive);
        u8 dma_stat             = hwif->INB(hwif->dma_status);

        printk(KERN_WARNING "%s: dma_timer_expiry: dma status == 0x%02x\n",
                drive->name, dma_stat);

        if ((dma_stat & 0x18) == 0x18)  /* BUSY Stupid Early Timer !! */
                return WAIT_CMD;

        HWGROUP(drive)->expiry = NULL;  /* one free ride for now */

        /* 1 dmaing, 2 error, 4 intr */
        if (dma_stat & 2)       /* ERROR */
                return -1;

        if (dma_stat & 1)       /* DMAing */
                return WAIT_CMD;

        if (dma_stat & 4)       /* Got an Interrupt */
                return WAIT_CMD;

        return 0;       /* Status is unknown -- reset the bus */
}

/**
 *      ide_dma_host_off        -       Generic DMA kill
 *      @drive: drive to control
 *
 *      Perform the generic IDE controller DMA off operation. This
 *      works for most IDE bus mastering controllers
 */

void ide_dma_host_off(ide_drive_t *drive)
{
        ide_hwif_t *hwif        = HWIF(drive);
        u8 unit                 = (drive->select.b.unit & 0x01);
        u8 dma_stat             = hwif->INB(hwif->dma_status);

        hwif->OUTB((dma_stat & ~(1<<(5+unit))), hwif->dma_status);
}

EXPORT_SYMBOL(ide_dma_host_off);

/**
 *      ide_dma_off_quietly     -       Generic DMA kill
 *      @drive: drive to control
 *
 *      Turn off the current DMA on this IDE controller. 
 */

void ide_dma_off_quietly(ide_drive_t *drive)
{
        drive->using_dma = 0;
        ide_toggle_bounce(drive, 0);

        drive->hwif->dma_host_off(drive);
}

EXPORT_SYMBOL(ide_dma_off_quietly);
#endif /* CONFIG_BLK_DEV_IDEDMA_PCI */

/**
 *      ide_dma_off     -       disable DMA on a device
 *      @drive: drive to disable DMA on
 *
 *      Disable IDE DMA for a device on this IDE controller.
 *      Inform the user that DMA has been disabled.
 */

void ide_dma_off(ide_drive_t *drive)
{
        printk(KERN_INFO "%s: DMA disabled\n", drive->name);
        drive->hwif->dma_off_quietly(drive);
}

EXPORT_SYMBOL(ide_dma_off);

#ifdef CONFIG_BLK_DEV_IDEDMA_PCI
/**
 *      ide_dma_host_on -       Enable DMA on a host
 *      @drive: drive to enable for DMA
 *
 *      Enable DMA on an IDE controller following generic bus mastering
 *      IDE controller behaviour
 */

void ide_dma_host_on(ide_drive_t *drive)
{
        if (drive->using_dma) {
                ide_hwif_t *hwif        = HWIF(drive);
                u8 unit                 = (drive->select.b.unit & 0x01);
                u8 dma_stat             = hwif->INB(hwif->dma_status);

                hwif->OUTB((dma_stat|(1<<(5+unit))), hwif->dma_status);
        }
}

EXPORT_SYMBOL(ide_dma_host_on);

/**
 *      __ide_dma_on            -       Enable DMA on a device
 *      @drive: drive to enable DMA on
 *
 *      Enable IDE DMA for a device on this IDE controller.
 */
 
int __ide_dma_on (ide_drive_t *drive)
{
        /* consult the list of known "bad" drives */
        if (__ide_dma_bad_drive(drive))
                return 1;

        drive->using_dma = 1;
        ide_toggle_bounce(drive, 1);

        drive->hwif->dma_host_on(drive);

        return 0;
}

EXPORT_SYMBOL(__ide_dma_on);

/**
 *      ide_dma_setup   -       begin a DMA phase
 *      @drive: target device
 *
 *      Build an IDE DMA PRD (IDE speak for scatter gather table)
 *      and then set up the DMA transfer registers for a device
 *      that follows generic IDE PCI DMA behaviour. Controllers can
 *      override this function if they need to
 *
 *      Returns 0 on success. If a PIO fallback is required then 1
 *      is returned. 
 */

int ide_dma_setup(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        struct request *rq = HWGROUP(drive)->rq;
        unsigned int reading;
        u8 dma_stat;

        if (rq_data_dir(rq))
                reading = 0;
        else
                reading = 1 << 3;

        /* fall back to pio! */
        if (!ide_build_dmatable(drive, rq)) {
                ide_map_sg(drive, rq);
                return 1;
        }

        /* PRD table */
        if (hwif->mmio)
                writel(hwif->dmatable_dma, (void __iomem *)hwif->dma_prdtable);
        else
                outl(hwif->dmatable_dma, hwif->dma_prdtable);

        /* specify r/w */
        hwif->OUTB(reading, hwif->dma_command);

        /* read dma_status for INTR & ERROR flags */
        dma_stat = hwif->INB(hwif->dma_status);

        /* clear INTR & ERROR flags */
        hwif->OUTB(dma_stat|6, hwif->dma_status);
        drive->waiting_for_dma = 1;
        return 0;
}

EXPORT_SYMBOL_GPL(ide_dma_setup);

static void ide_dma_exec_cmd(ide_drive_t *drive, u8 command)
{
        /* issue cmd to drive */
        ide_execute_command(drive, command, &ide_dma_intr, 2*WAIT_CMD, dma_timer_expiry);
}

void ide_dma_start(ide_drive_t *drive)
{
        ide_hwif_t *hwif        = HWIF(drive);
        u8 dma_cmd              = hwif->INB(hwif->dma_command);

        /* Note that this is done *after* the cmd has
         * been issued to the drive, as per the BM-IDE spec.
         * The Promise Ultra33 doesn't work correctly when
         * we do this part before issuing the drive cmd.
         */
        /* start DMA */
        hwif->OUTB(dma_cmd|1, hwif->dma_command);
        hwif->dma = 1;
        wmb();
}

EXPORT_SYMBOL_GPL(ide_dma_start);

/* returns 1 on error, 0 otherwise */
int __ide_dma_end (ide_drive_t *drive)
{
        ide_hwif_t *hwif        = HWIF(drive);
        u8 dma_stat = 0, dma_cmd = 0;

        drive->waiting_for_dma = 0;
        /* get dma_command mode */
        dma_cmd = hwif->INB(hwif->dma_command);
        /* stop DMA */
        hwif->OUTB(dma_cmd&~1, hwif->dma_command);
        /* get DMA status */
        dma_stat = hwif->INB(hwif->dma_status);
        /* clear the INTR & ERROR bits */
        hwif->OUTB(dma_stat|6, hwif->dma_status);
        /* purge DMA mappings */
        ide_destroy_dmatable(drive);
        /* verify good DMA status */
        hwif->dma = 0;
        wmb();
        return (dma_stat & 7) != 4 ? (0x10 | dma_stat) : 0;
}

EXPORT_SYMBOL(__ide_dma_end);

/* returns 1 if dma irq issued, 0 otherwise */
static int __ide_dma_test_irq(ide_drive_t *drive)
{
        ide_hwif_t *hwif        = HWIF(drive);
        u8 dma_stat             = hwif->INB(hwif->dma_status);

        /* return 1 if INTR asserted */
        if ((dma_stat & 4) == 4)
                return 1;
        if (!drive->waiting_for_dma)
                printk(KERN_WARNING "%s: (%s) called while not waiting\n",
                        drive->name, __FUNCTION__);
        return 0;
}
#else
static inline int config_drive_for_dma(ide_drive_t *drive) { return 0; }
#endif /* CONFIG_BLK_DEV_IDEDMA_PCI */

int __ide_dma_bad_drive (ide_drive_t *drive)
{
        struct hd_driveid *id = drive->id;

        int blacklist = ide_in_drive_list(id, drive_blacklist);
        if (blacklist) {
                printk(KERN_WARNING "%s: Disabling (U)DMA for %s (blacklisted)\n",
                                    drive->name, id->model);
                return blacklist;
        }
        return 0;
}

EXPORT_SYMBOL(__ide_dma_bad_drive);

static const u8 xfer_mode_bases[] = {
        XFER_UDMA_0,
        XFER_MW_DMA_0,
        XFER_SW_DMA_0,
};

static unsigned int ide_get_mode_mask(ide_drive_t *drive, u8 base, u8 req_mode)
{
        struct hd_driveid *id = drive->id;
        ide_hwif_t *hwif = drive->hwif;
        unsigned int mask = 0;

        switch(base) {
        case XFER_UDMA_0:
                if ((id->field_valid & 4) == 0)
                        break;

                if (hwif->udma_filter)
                        mask = hwif->udma_filter(drive);
                else
                        mask = hwif->ultra_mask;
                mask &= id->dma_ultra;

                /*
                 * avoid false cable warning from eighty_ninty_three()
                 */
                if (req_mode > XFER_UDMA_2) {
                        if ((mask & 0x78) && (eighty_ninty_three(drive) == 0))
                                mask &= 0x07;
                }
                break;
        case XFER_MW_DMA_0:
                if ((id->field_valid & 2) == 0)
                        break;
                if (hwif->mdma_filter)
                        mask = hwif->mdma_filter(drive);
                else
                        mask = hwif->mwdma_mask;
                mask &= id->dma_mword;
                break;
        case XFER_SW_DMA_0:
                if (id->field_valid & 2) {
                        mask = id->dma_1word & hwif->swdma_mask;
                } else if (id->tDMA) {
                        /*
                         * ide_fix_driveid() doesn't convert ->tDMA to the
                         * CPU endianness so we need to do it here
                         */
                        u8 mode = le16_to_cpu(id->tDMA);

                        /*
                         * if the mode is valid convert it to the mask
                         * (the maximum allowed mode is XFER_SW_DMA_2)
                         */
                        if (mode <= 2)
                                mask = ((2 << mode) - 1) & hwif->swdma_mask;
                }
                break;
        default:
                BUG();
                break;
        }

        return mask;
}

/**
 *      ide_find_dma_mode       -       compute DMA speed
 *      @drive: IDE device
 *      @req_mode: requested mode
 *
 *      Checks the drive/host capabilities and finds the speed to use for
 *      the DMA transfer.  The speed is then limited by the requested mode.
 *
 *      Returns 0 if the drive/host combination is incapable of DMA transfers
 *      or if the requested mode is not a DMA mode.
 */

u8 ide_find_dma_mode(ide_drive_t *drive, u8 req_mode)
{
        ide_hwif_t *hwif = drive->hwif;
        unsigned int mask;
        int x, i;
        u8 mode = 0;

        if (drive->media != ide_disk) {
                if (hwif->host_flags & IDE_HFLAG_NO_ATAPI_DMA)
                        return 0;
        }

        for (i = 0; i < ARRAY_SIZE(xfer_mode_bases); i++) {
                if (req_mode < xfer_mode_bases[i])
                        continue;
                mask = ide_get_mode_mask(drive, xfer_mode_bases[i], req_mode);
                x = fls(mask) - 1;
                if (x >= 0) {
                        mode = xfer_mode_bases[i] + x;
                        break;
                }
        }

        if (hwif->chipset == ide_acorn && mode == 0) {
                /*
                 * is this correct?
                 */
                if (ide_dma_good_drive(drive) && drive->id->eide_dma_time < 150)
                        mode = XFER_MW_DMA_1;
        }

        mode = min(mode, req_mode);

        printk(KERN_INFO "%s: %s mode selected\n", drive->name,
                          mode ? ide_xfer_verbose(mode) : "no DMA");

        return mode;
}

EXPORT_SYMBOL_GPL(ide_find_dma_mode);

static int ide_tune_dma(ide_drive_t *drive)
{
        u8 speed;

        if (noautodma || drive->nodma || (drive->id->capability & 1) == 0)
                return 0;

        /* consult the list of known "bad" drives */
        if (__ide_dma_bad_drive(drive))
                return 0;

        if (ide_id_dma_bug(drive))
                return 0;

        if (drive->hwif->host_flags & IDE_HFLAG_TRUST_BIOS_FOR_DMA)
                return config_drive_for_dma(drive);

        speed = ide_max_dma_mode(drive);

        if (!speed)
                return 0;

        if (drive->hwif->host_flags & IDE_HFLAG_NO_SET_MODE)
                return 0;

        if (ide_set_dma_mode(drive, speed))
                return 0;

        return 1;
}

static int ide_dma_check(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        int vdma = (hwif->host_flags & IDE_HFLAG_VDMA)? 1 : 0;

        if (!vdma && ide_tune_dma(drive))
                return 0;

        /* TODO: always do PIO fallback */
        if (hwif->host_flags & IDE_HFLAG_TRUST_BIOS_FOR_DMA)
                return -1;

        ide_set_max_pio(drive);

        return vdma ? 0 : -1;
}

int ide_id_dma_bug(ide_drive_t *drive)
{
        struct hd_driveid *id = drive->id;

        if (id->field_valid & 4) {
                if ((id->dma_ultra >> 8) && (id->dma_mword >> 8))
                        goto err_out;
        } else if (id->field_valid & 2) {
                if ((id->dma_mword >> 8) && (id->dma_1word >> 8))
                        goto err_out;
        }
        return 0;
err_out:
        printk(KERN_ERR "%s: bad DMA info in identify block\n", drive->name);
        return 1;
}

int ide_set_dma(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        int rc;

        rc = ide_dma_check(drive);

        switch(rc) {
        case -1: /* DMA needs to be disabled */
                hwif->dma_off_quietly(drive);
                return -1;
        case  0: /* DMA needs to be enabled */
                return hwif->ide_dma_on(drive);
        case  1: /* DMA setting cannot be changed */
                break;
        default:
                BUG();
                break;
        }

        return rc;
}

#ifdef CONFIG_BLK_DEV_IDEDMA_PCI
void ide_dma_lost_irq (ide_drive_t *drive)
{
        printk("%s: DMA interrupt recovery\n", drive->name);
}

EXPORT_SYMBOL(ide_dma_lost_irq);

void ide_dma_timeout (ide_drive_t *drive)
{
        ide_hwif_t *hwif = HWIF(drive);

        printk(KERN_ERR "%s: timeout waiting for DMA\n", drive->name);

        if (hwif->ide_dma_test_irq(drive))
                return;

        hwif->ide_dma_end(drive);
}

EXPORT_SYMBOL(ide_dma_timeout);

static void ide_release_dma_engine(ide_hwif_t *hwif)
{
        if (hwif->dmatable_cpu) {
                pci_free_consistent(hwif->pci_dev,
                                    PRD_ENTRIES * PRD_BYTES,
                                    hwif->dmatable_cpu,
                                    hwif->dmatable_dma);
                hwif->dmatable_cpu = NULL;
        }
}

static int ide_release_iomio_dma(ide_hwif_t *hwif)
{
        release_region(hwif->dma_base, 8);
        if (hwif->extra_ports)
                release_region(hwif->extra_base, hwif->extra_ports);
        return 1;
}

/*
 * Needed for allowing full modular support of ide-driver
 */
int ide_release_dma(ide_hwif_t *hwif)
{
        ide_release_dma_engine(hwif);

        if (hwif->mmio)
                return 1;
        else
                return ide_release_iomio_dma(hwif);
}

static int ide_allocate_dma_engine(ide_hwif_t *hwif)
{
        hwif->dmatable_cpu = pci_alloc_consistent(hwif->pci_dev,
                                                  PRD_ENTRIES * PRD_BYTES,
                                                  &hwif->dmatable_dma);

        if (hwif->dmatable_cpu)
                return 0;

        printk(KERN_ERR "%s: -- Error, unable to allocate DMA table.\n",
               hwif->cds->name);

        return 1;
}

static int ide_mapped_mmio_dma(ide_hwif_t *hwif, unsigned long base, unsigned int ports)
{
        printk(KERN_INFO "    %s: MMIO-DMA ", hwif->name);

        return 0;
}

static int ide_iomio_dma(ide_hwif_t *hwif, unsigned long base, unsigned int ports)
{
        printk(KERN_INFO "    %s: BM-DMA at 0x%04lx-0x%04lx",
               hwif->name, base, base + ports - 1);

        if (!request_region(base, ports, hwif->name)) {
                printk(" -- Error, ports in use.\n");
                return 1;
        }

        if (hwif->cds->extra) {
                hwif->extra_base = base + (hwif->channel ? 8 : 16);

                if (!hwif->mate || !hwif->mate->extra_ports) {
                        if (!request_region(hwif->extra_base,
                                            hwif->cds->extra, hwif->cds->name)) {
                                printk(" -- Error, extra ports in use.\n");
                                release_region(base, ports);
                                return 1;
                        }
                        hwif->extra_ports = hwif->cds->extra;
                }
        }

        return 0;
}

static int ide_dma_iobase(ide_hwif_t *hwif, unsigned long base, unsigned int ports)
{
        if (hwif->mmio)
                return ide_mapped_mmio_dma(hwif, base,ports);

        return ide_iomio_dma(hwif, base, ports);
}

void ide_setup_dma(ide_hwif_t *hwif, unsigned long base, unsigned num_ports)
{
        if (ide_dma_iobase(hwif, base, num_ports))
                return;

        if (ide_allocate_dma_engine(hwif)) {
                ide_release_dma(hwif);
                return;
        }

        hwif->dma_base = base;

        if (hwif->mate)
                hwif->dma_master = hwif->channel ? hwif->mate->dma_base : base;
        else
                hwif->dma_master = base;

        if (!(hwif->dma_command))
                hwif->dma_command       = hwif->dma_base;
        if (!(hwif->dma_vendor1))
                hwif->dma_vendor1       = (hwif->dma_base + 1);
        if (!(hwif->dma_status))
                hwif->dma_status        = (hwif->dma_base + 2);
        if (!(hwif->dma_vendor3))
                hwif->dma_vendor3       = (hwif->dma_base + 3);
        if (!(hwif->dma_prdtable))
                hwif->dma_prdtable      = (hwif->dma_base + 4);

        if (!hwif->dma_off_quietly)
                hwif->dma_off_quietly = &ide_dma_off_quietly;
        if (!hwif->dma_host_off)
                hwif->dma_host_off = &ide_dma_host_off;
        if (!hwif->ide_dma_on)
                hwif->ide_dma_on = &__ide_dma_on;
        if (!hwif->dma_host_on)
                hwif->dma_host_on = &ide_dma_host_on;
        if (!hwif->dma_setup)
                hwif->dma_setup = &ide_dma_setup;
        if (!hwif->dma_exec_cmd)
                hwif->dma_exec_cmd = &ide_dma_exec_cmd;
        if (!hwif->dma_start)
                hwif->dma_start = &ide_dma_start;

        if (!hwif->ide_dma_end)
                hwif->ide_dma_end = &__ide_dma_end;
        if (!hwif->ide_dma_test_irq)
                hwif->ide_dma_test_irq = &__ide_dma_test_irq;
        if (!hwif->dma_timeout)
                hwif->dma_timeout = &ide_dma_timeout;
        if (!hwif->dma_lost_irq)
                hwif->dma_lost_irq = &ide_dma_lost_irq;

        if (hwif->chipset != ide_trm290) {
                u8 dma_stat = hwif->INB(hwif->dma_status);
                printk(", BIOS settings: %s:%s, %s:%s",
                       hwif->drives[0].name, (dma_stat & 0x20) ? "DMA" : "pio",
                       hwif->drives[1].name, (dma_stat & 0x40) ? "DMA" : "pio");
        }
        printk("\n");

        BUG_ON(!hwif->dma_master);
}

EXPORT_SYMBOL_GPL(ide_setup_dma);
#endif /* CONFIG_BLK_DEV_IDEDMA_PCI */