/*
 *  IDE DMA support (including IDE PCI BM-DMA).
 *
 *  Copyright (C) 1995-1998   Mark Lord
 *  Copyright (C) 1999-2000   Andre Hedrick <andre@linux-ide.org>
 *  Copyright (C) 2004, 2007  Bartlomiej Zolnierkiewicz
 *
 *  May be copied or modified under the terms of the GNU General Public License
 *
 *  DMA is supported for all IDE devices (disk drives, cdroms, tapes, floppies).
 */

/*
 *  Special Thanks to Mark for his Six years of work.
 */

/*
 * 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!
 */

#include <linux/types.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/ide.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.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)
{
        ide_hwif_t *hwif = drive->hwif;
        struct ide_cmd *cmd = &hwif->cmd;
        u8 stat = 0, dma_stat = 0;

        drive->waiting_for_dma = 0;
        dma_stat = hwif->dma_ops->dma_end(drive);
        ide_dma_unmap_sg(drive, cmd);
        stat = hwif->tp_ops->read_status(hwif);

        if (OK_STAT(stat, DRIVE_READY, drive->bad_wstat | ATA_DRQ)) {
                if (!dma_stat) {
                        if ((cmd->tf_flags & IDE_TFLAG_FS) == 0)
                                ide_finish_cmd(drive, cmd, stat);
                        else
                                ide_complete_rq(drive, BLK_STS_OK,
                                                blk_rq_sectors(cmd->rq) << 9);
                        return ide_stopped;
                }
                printk(KERN_ERR "%s: %s: bad DMA status (0x%02x)\n",
                        drive->name, __func__, dma_stat);
        }
        return ide_error(drive, "dma_intr", stat);
}

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

/**
 *      ide_dma_map_sg  -       map IDE scatter gather for DMA I/O
 *      @drive: the drive to map the DMA table for
 *      @cmd: command
 *
 *      Perform the DMA mapping magic necessary to access the source or
 *      target buffers of a request via DMA.  The lower layers of the
 *      kernel provide the necessary cache management so that we can
 *      operate in a portable fashion.
 */

static int ide_dma_map_sg(ide_drive_t *drive, struct ide_cmd *cmd)
{
        ide_hwif_t *hwif = drive->hwif;
        struct scatterlist *sg = hwif->sg_table;
        int i;

        if (cmd->tf_flags & IDE_TFLAG_WRITE)
                cmd->sg_dma_direction = DMA_TO_DEVICE;
        else
                cmd->sg_dma_direction = DMA_FROM_DEVICE;

        i = dma_map_sg(hwif->dev, sg, cmd->sg_nents, cmd->sg_dma_direction);
        if (i) {
                cmd->orig_sg_nents = cmd->sg_nents;
                cmd->sg_nents = i;
        }

        return i;
}

/**
 *      ide_dma_unmap_sg        -       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_dma_unmap_sg(ide_drive_t *drive, struct ide_cmd *cmd)
{
        ide_hwif_t *hwif = drive->hwif;

        dma_unmap_sg(hwif->dev, hwif->sg_table, cmd->orig_sg_nents,
                     cmd->sg_dma_direction);
}
EXPORT_SYMBOL_GPL(ide_dma_unmap_sg);

/**
 *      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->dev_flags &= ~IDE_DFLAG_USING_DMA;

        drive->hwif->dma_ops->dma_host_set(drive, 0);
}
EXPORT_SYMBOL(ide_dma_off_quietly);

/**
 *      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);
        ide_dma_off_quietly(drive);
}
EXPORT_SYMBOL(ide_dma_off);

/**
 *      ide_dma_on              -       Enable DMA on a device
 *      @drive: drive to enable DMA on
 *
 *      Enable IDE DMA for a device on this IDE controller.
 */

void ide_dma_on(ide_drive_t *drive)
{
        drive->dev_flags |= IDE_DFLAG_USING_DMA;

        drive->hwif->dma_ops->dma_host_set(drive, 1);
}

int __ide_dma_bad_drive(ide_drive_t *drive)
{
        u16 *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, (char *)&id[ATA_ID_PROD]);
                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)
{
        u16 *id = drive->id;
        ide_hwif_t *hwif = drive->hwif;
        const struct ide_port_ops *port_ops = hwif->port_ops;
        unsigned int mask = 0;

        switch (base) {
        case XFER_UDMA_0:
                if ((id[ATA_ID_FIELD_VALID] & 4) == 0)
                        break;
                mask = id[ATA_ID_UDMA_MODES];
                if (port_ops && port_ops->udma_filter)
                        mask &= port_ops->udma_filter(drive);
                else
                        mask &= hwif->ultra_mask;

                /*
                 * 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:
                mask = id[ATA_ID_MWDMA_MODES];

                /* Also look for the CF specific MWDMA modes... */
                if (ata_id_is_cfa(id) && (id[ATA_ID_CFA_MODES] & 0x38)) {
                        u8 mode = ((id[ATA_ID_CFA_MODES] & 0x38) >> 3) - 1;

                        mask |= ((2 << mode) - 1) << 3;
                }

                if (port_ops && port_ops->mdma_filter)
                        mask &= port_ops->mdma_filter(drive);
                else
                        mask &= hwif->mwdma_mask;
                break;
        case XFER_SW_DMA_0:
                mask = id[ATA_ID_SWDMA_MODES];
                if (!(mask & ATA_SWDMA2) && (id[ATA_ID_OLD_DMA_MODES] >> 8)) {
                        u8 mode = id[ATA_ID_OLD_DMA_MODES] >> 8;

                        /*
                         * 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;
                }
                mask &= 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[ATA_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;
}

static int ide_tune_dma(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        u8 speed;

        if (ata_id_has_dma(drive->id) == 0 ||
            (drive->dev_flags & IDE_DFLAG_NODMA))
                return 0;

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

        if (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 (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;

        if (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 -1;
}

int ide_set_dma(ide_drive_t *drive)
{
        int rc;

        /*
         * Force DMAing for the beginning of the check.
         * Some chipsets appear to do interesting
         * things, if not checked and cleared.
         *   PARANOIA!!!
         */
        ide_dma_off_quietly(drive);

        rc = ide_dma_check(drive);
        if (rc)
                return rc;

        ide_dma_on(drive);

        return 0;
}

void ide_check_dma_crc(ide_drive_t *drive)
{
        u8 mode;

        ide_dma_off_quietly(drive);
        drive->crc_count = 0;
        mode = drive->current_speed;
        /*
         * Don't try non Ultra-DMA modes without iCRC's.  Force the
         * device to PIO and make the user enable SWDMA/MWDMA modes.
         */
        if (mode > XFER_UDMA_0 && mode <= XFER_UDMA_7)
                mode--;
        else
                mode = XFER_PIO_4;
        ide_set_xfer_rate(drive, mode);
        if (drive->current_speed >= XFER_SW_DMA_0)
                ide_dma_on(drive);
}

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

/*
 * un-busy the port etc, and clear any pending DMA status. we want to
 * retry the current request in pio mode instead of risking tossing it
 * all away
 */
ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error)
{
        ide_hwif_t *hwif = drive->hwif;
        const struct ide_dma_ops *dma_ops = hwif->dma_ops;
        struct ide_cmd *cmd = &hwif->cmd;
        ide_startstop_t ret = ide_stopped;

        /*
         * end current dma transaction
         */

        if (error < 0) {
                printk(KERN_WARNING "%s: DMA timeout error\n", drive->name);
                drive->waiting_for_dma = 0;
                (void)dma_ops->dma_end(drive);
                ide_dma_unmap_sg(drive, cmd);
                ret = ide_error(drive, "dma timeout error",
                                hwif->tp_ops->read_status(hwif));
        } else {
                printk(KERN_WARNING "%s: DMA timeout retry\n", drive->name);
                if (dma_ops->dma_clear)
                        dma_ops->dma_clear(drive);
                printk(KERN_ERR "%s: timeout waiting for DMA\n", drive->name);
                if (dma_ops->dma_test_irq(drive) == 0) {
                        ide_dump_status(drive, "DMA timeout",
                                        hwif->tp_ops->read_status(hwif));
                        drive->waiting_for_dma = 0;
                        (void)dma_ops->dma_end(drive);
                        ide_dma_unmap_sg(drive, cmd);
                }
        }

        /*
         * disable dma for now, but remember that we did so because of
         * a timeout -- we'll reenable after we finish this next request
         * (or rather the first chunk of it) in pio.
         */
        drive->dev_flags |= IDE_DFLAG_DMA_PIO_RETRY;
        drive->retry_pio++;
        ide_dma_off_quietly(drive);

        /*
         * make sure request is sane
         */
        if (hwif->rq)
                scsi_req(hwif->rq)->result = 0;
        return ret;
}

void ide_release_dma_engine(ide_hwif_t *hwif)
{
        if (hwif->dmatable_cpu) {
                int prd_size = hwif->prd_max_nents * hwif->prd_ent_size;

                dma_free_coherent(hwif->dev, prd_size,
                                  hwif->dmatable_cpu, hwif->dmatable_dma);
                hwif->dmatable_cpu = NULL;
        }
}
EXPORT_SYMBOL_GPL(ide_release_dma_engine);

int ide_allocate_dma_engine(ide_hwif_t *hwif)
{
        int prd_size;

        if (hwif->prd_max_nents == 0)
                hwif->prd_max_nents = PRD_ENTRIES;
        if (hwif->prd_ent_size == 0)
                hwif->prd_ent_size = PRD_BYTES;

        prd_size = hwif->prd_max_nents * hwif->prd_ent_size;

        hwif->dmatable_cpu = dma_alloc_coherent(hwif->dev, prd_size,
                                                &hwif->dmatable_dma,
                                                GFP_ATOMIC);
        if (hwif->dmatable_cpu == NULL) {
                printk(KERN_ERR "%s: unable to allocate PRD table\n",
                        hwif->name);
                return -ENOMEM;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(ide_allocate_dma_engine);

int ide_dma_prepare(ide_drive_t *drive, struct ide_cmd *cmd)
{
        const struct ide_dma_ops *dma_ops = drive->hwif->dma_ops;

        if ((drive->dev_flags & IDE_DFLAG_USING_DMA) == 0 ||
            (dma_ops->dma_check && dma_ops->dma_check(drive, cmd)))
                goto out;
        ide_map_sg(drive, cmd);
        if (ide_dma_map_sg(drive, cmd) == 0)
                goto out_map;
        if (dma_ops->dma_setup(drive, cmd))
                goto out_dma_unmap;
        drive->waiting_for_dma = 1;
        return 0;
out_dma_unmap:
        ide_dma_unmap_sg(drive, cmd);
out_map:
        ide_map_sg(drive, cmd);
out:
        return 1;
}