#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ide.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/io.h>

/**
 *      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.
 */

int config_drive_for_dma(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        u16 *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[ATA_ID_FIELD_VALID] & 4) &&
            ((id[ATA_ID_UDMA_MODES] >> 8) & 0x7f))
                return 1;

        /*
         * Enable DMA on any drive that has mode2 DMA
         * (multi or single) enabled
         */
        if ((id[ATA_ID_MWDMA_MODES] & 0x404) == 0x404 ||
            (id[ATA_ID_SWDMA_MODES] & 0x404) == 0x404)
                return 1;

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

        return 0;
}

u8 ide_dma_sff_read_status(ide_hwif_t *hwif)
{
        unsigned long addr = hwif->dma_base + ATA_DMA_STATUS;

        if (hwif->host_flags & IDE_HFLAG_MMIO)
                return readb((void __iomem *)addr);
        else
                return inb(addr);
}
EXPORT_SYMBOL_GPL(ide_dma_sff_read_status);

static void ide_dma_sff_write_status(ide_hwif_t *hwif, u8 val)
{
        unsigned long addr = hwif->dma_base + ATA_DMA_STATUS;

        if (hwif->host_flags & IDE_HFLAG_MMIO)
                writeb(val, (void __iomem *)addr);
        else
                outb(val, addr);
}

/**
 *      ide_dma_host_set        -       Enable/disable DMA on a host
 *      @drive: drive to control
 *
 *      Enable/disable DMA on an IDE controller following generic
 *      bus-mastering IDE controller behaviour.
 */

void ide_dma_host_set(ide_drive_t *drive, int on)
{
        ide_hwif_t *hwif = drive->hwif;
        u8 unit = drive->dn & 1;
        u8 dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);

        if (on)
                dma_stat |= (1 << (5 + unit));
        else
                dma_stat &= ~(1 << (5 + unit));

        ide_dma_sff_write_status(hwif, dma_stat);
}
EXPORT_SYMBOL_GPL(ide_dma_host_set);

/**
 *      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.
 *
 *      Most chipsets correctly interpret a length of 0x0000 as 64KB,
 *      but at least one (e.g. CS5530) misinterprets it as zero (!).
 *      So we break the 64KB entry into two 32KB entries instead.
 *
 *      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 ide_cmd *cmd)
{
        ide_hwif_t *hwif = drive->hwif;
        __le32 *table = (__le32 *)hwif->dmatable_cpu;
        unsigned int count = 0;
        int i;
        struct scatterlist *sg;
        u8 is_trm290 = !!(hwif->host_flags & IDE_HFLAG_TRM290);

        for_each_sg(hwif->sg_table, sg, cmd->sg_nents, i) {
                u32 cur_addr, cur_len, xcount, bcount;

                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)
                                goto use_pio_instead;

                        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;
                        else if (xcount == 0x0000) {
                                if (count++ >= PRD_ENTRIES)
                                        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;
                }
        }

        if (count) {
                if (!is_trm290)
                        *--table |= cpu_to_le32(0x80000000);
                return count;
        }

use_pio_instead:
        printk(KERN_ERR "%s: %s\n", drive->name,
                count ? "DMA table too small" : "empty DMA table?");

        return 0; /* revert to PIO for this request */
}
EXPORT_SYMBOL_GPL(ide_build_dmatable);

/**
 *      ide_dma_setup   -       begin a DMA phase
 *      @drive: target device
 *      @cmd: command
 *
 *      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, struct ide_cmd *cmd)
{
        ide_hwif_t *hwif = drive->hwif;
        u8 mmio = (hwif->host_flags & IDE_HFLAG_MMIO) ? 1 : 0;
        u8 rw = (cmd->tf_flags & IDE_TFLAG_WRITE) ? 0 : ATA_DMA_WR;
        u8 dma_stat;

        /* fall back to pio! */
        if (ide_build_dmatable(drive, cmd) == 0) {
                ide_map_sg(drive, cmd);
                return 1;
        }

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

        /* specify r/w */
        if (mmio)
                writeb(rw, (void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
        else
                outb(rw, hwif->dma_base + ATA_DMA_CMD);

        /* read DMA status for INTR & ERROR flags */
        dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);

        /* clear INTR & ERROR flags */
        ide_dma_sff_write_status(hwif, dma_stat | ATA_DMA_ERR | ATA_DMA_INTR);

        return 0;
}
EXPORT_SYMBOL_GPL(ide_dma_setup);

/**
 *      ide_dma_sff_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.
 */

int ide_dma_sff_timer_expiry(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        u8 dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);

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

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

        hwif->expiry = NULL;    /* one free ride for now */

        if (dma_stat & ATA_DMA_ERR)     /* ERROR */
                return -1;

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

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

        return 0;       /* Status is unknown -- reset the bus */
}
EXPORT_SYMBOL_GPL(ide_dma_sff_timer_expiry);

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

        /* 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.
         */
        if (hwif->host_flags & IDE_HFLAG_MMIO) {
                dma_cmd = readb((void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
                writeb(dma_cmd | ATA_DMA_START,
                       (void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
        } else {
                dma_cmd = inb(hwif->dma_base + ATA_DMA_CMD);
                outb(dma_cmd | ATA_DMA_START, hwif->dma_base + ATA_DMA_CMD);
        }
}
EXPORT_SYMBOL_GPL(ide_dma_start);

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

        /* stop DMA */
        if (hwif->host_flags & IDE_HFLAG_MMIO) {
                dma_cmd = readb((void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
                writeb(dma_cmd & ~ATA_DMA_START,
                       (void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
        } else {
                dma_cmd = inb(hwif->dma_base + ATA_DMA_CMD);
                outb(dma_cmd & ~ATA_DMA_START, hwif->dma_base + ATA_DMA_CMD);
        }

        /* get DMA status */
        dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);

        /* clear INTR & ERROR bits */
        ide_dma_sff_write_status(hwif, dma_stat | ATA_DMA_ERR | ATA_DMA_INTR);

#define CHECK_DMA_MASK (ATA_DMA_ACTIVE | ATA_DMA_ERR | ATA_DMA_INTR)

        /* verify good DMA status */
        if ((dma_stat & CHECK_DMA_MASK) != ATA_DMA_INTR)
                return 0x10 | dma_stat;
        return 0;
}
EXPORT_SYMBOL_GPL(ide_dma_end);

/* returns 1 if dma irq issued, 0 otherwise */
int ide_dma_test_irq(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        u8 dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);

        return (dma_stat & ATA_DMA_INTR) ? 1 : 0;
}
EXPORT_SYMBOL_GPL(ide_dma_test_irq);

const struct ide_dma_ops sff_dma_ops = {
        .dma_host_set           = ide_dma_host_set,
        .dma_setup              = ide_dma_setup,
        .dma_start              = ide_dma_start,
        .dma_end                = ide_dma_end,
        .dma_test_irq           = ide_dma_test_irq,
        .dma_lost_irq           = ide_dma_lost_irq,
        .dma_timer_expiry       = ide_dma_sff_timer_expiry,
        .dma_sff_read_status    = ide_dma_sff_read_status,
};
EXPORT_SYMBOL_GPL(sff_dma_ops);