/*
 * pata_sl82c105.c      - SL82C105 PATA for new ATA layer
 *                        (C) 2005 Red Hat Inc
 *
 * Based in part on linux/drivers/ide/pci/sl82c105.c
 *              SL82C105/Winbond 553 IDE driver
 *
 * and in part on the documentation and errata sheet
 *
 *
 * Note: The controller like many controllers has shared timings for
 * PIO and DMA. We thus flip to the DMA timings in dma_start and flip back
 * in the dma_stop function. Thus we actually don't need a set_dmamode
 * method as the PIO method is always called and will set the right PIO
 * timing parameters.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <scsi/scsi_host.h>
#include <linux/libata.h>

#define DRV_NAME "pata_sl82c105"
#define DRV_VERSION "0.3.3"

enum {
        /*
         * SL82C105 PCI config register 0x40 bits.
         */
        CTRL_IDE_IRQB   =       (1 << 30),
        CTRL_IDE_IRQA   =       (1 << 28),
        CTRL_LEGIRQ     =       (1 << 11),
        CTRL_P1F16      =       (1 << 5),
        CTRL_P1EN       =       (1 << 4),
        CTRL_P0F16      =       (1 << 1),
        CTRL_P0EN       =       (1 << 0)
};

/**
 *      sl82c105_pre_reset              -       probe begin
 *      @link: ATA link
 *      @deadline: deadline jiffies for the operation
 *
 *      Set up cable type and use generic probe init
 */

static int sl82c105_pre_reset(struct ata_link *link, unsigned long deadline)
{
        static const struct pci_bits sl82c105_enable_bits[] = {
                { 0x40, 1, 0x01, 0x01 },
                { 0x40, 1, 0x10, 0x10 }
        };
        struct ata_port *ap = link->ap;
        struct pci_dev *pdev = to_pci_dev(ap->host->dev);

        if (ap->port_no && !pci_test_config_bits(pdev, &sl82c105_enable_bits[ap->port_no]))
                return -ENOENT;
        return ata_sff_prereset(link, deadline);
}


/**
 *      sl82c105_configure_piomode      -       set chip PIO timing
 *      @ap: ATA interface
 *      @adev: ATA device
 *      @pio: PIO mode
 *
 *      Called to do the PIO mode setup. Our timing registers are shared
 *      so a configure_dmamode call will undo any work we do here and vice
 *      versa
 */

static void sl82c105_configure_piomode(struct ata_port *ap, struct ata_device *adev, int pio)
{
        struct pci_dev *pdev = to_pci_dev(ap->host->dev);
        static u16 pio_timing[5] = {
                0x50D, 0x407, 0x304, 0x242, 0x240
        };
        u16 dummy;
        int timing = 0x44 + (8 * ap->port_no) + (4 * adev->devno);

        pci_write_config_word(pdev, timing, pio_timing[pio]);
        /* Can we lose this oddity of the old driver */
        pci_read_config_word(pdev, timing, &dummy);
}

/**
 *      sl82c105_set_piomode    -       set initial PIO mode data
 *      @ap: ATA interface
 *      @adev: ATA device
 *
 *      Called to do the PIO mode setup. Our timing registers are shared
 *      but we want to set the PIO timing by default.
 */

static void sl82c105_set_piomode(struct ata_port *ap, struct ata_device *adev)
{
        sl82c105_configure_piomode(ap, adev, adev->pio_mode - XFER_PIO_0);
}

/**
 *      sl82c105_configure_dmamode      -       set DMA mode in chip
 *      @ap: ATA interface
 *      @adev: ATA device
 *
 *      Load DMA cycle times into the chip ready for a DMA transfer
 *      to occur.
 */

static void sl82c105_configure_dmamode(struct ata_port *ap, struct ata_device *adev)
{
        struct pci_dev *pdev = to_pci_dev(ap->host->dev);
        static u16 dma_timing[3] = {
                0x707, 0x201, 0x200
        };
        u16 dummy;
        int timing = 0x44 + (8 * ap->port_no) + (4 * adev->devno);
        int dma = adev->dma_mode - XFER_MW_DMA_0;

        pci_write_config_word(pdev, timing, dma_timing[dma]);
        /* Can we lose this oddity of the old driver */
        pci_read_config_word(pdev, timing, &dummy);
}

/**
 *      sl82c105_reset_engine   -       Reset the DMA engine
 *      @ap: ATA interface
 *
 *      The sl82c105 has some serious problems with the DMA engine
 *      when transfers don't run as expected or ATAPI is used. The
 *      recommended fix is to reset the engine each use using a chip
 *      test register.
 */

static void sl82c105_reset_engine(struct ata_port *ap)
{
        struct pci_dev *pdev = to_pci_dev(ap->host->dev);
        u16 val;

        pci_read_config_word(pdev, 0x7E, &val);
        pci_write_config_word(pdev, 0x7E, val | 4);
        pci_write_config_word(pdev, 0x7E, val & ~4);
}

/**
 *      sl82c105_bmdma_start            -       DMA engine begin
 *      @qc: ATA command
 *
 *      Reset the DMA engine each use as recommended by the errata
 *      document.
 *
 *      FIXME: if we switch clock at BMDMA start/end we might get better
 *      PIO performance on DMA capable devices.
 */

static void sl82c105_bmdma_start(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        udelay(100);
        sl82c105_reset_engine(ap);
        udelay(100);

        /* Set the clocks for DMA */
        sl82c105_configure_dmamode(ap, qc->dev);
        /* Activate DMA */
        ata_bmdma_start(qc);
}

/**
 *      sl82c105_bmdma_end              -       DMA engine stop
 *      @qc: ATA command
 *
 *      Reset the DMA engine each use as recommended by the errata
 *      document.
 *
 *      This function is also called to turn off DMA when a timeout occurs
 *      during DMA operation. In both cases we need to reset the engine,
 *      so no actual eng_timeout handler is required.
 *
 *      We assume bmdma_stop is always called if bmdma_start as called. If
 *      not then we may need to wrap qc_issue.
 */

static void sl82c105_bmdma_stop(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        ata_bmdma_stop(qc);
        sl82c105_reset_engine(ap);
        udelay(100);

        /* This will redo the initial setup of the DMA device to matching
           PIO timings */
        sl82c105_set_piomode(ap, qc->dev);
}

/**
 *      sl82c105_qc_defer       -       implement serialization
 *      @qc: command
 *
 *      We must issue one command per host not per channel because
 *      of the reset bug.
 *
 *      Q: is the scsi host lock sufficient ?
 */

static int sl82c105_qc_defer(struct ata_queued_cmd *qc)
{
        struct ata_host *host = qc->ap->host;
        struct ata_port *alt = host->ports[1 ^ qc->ap->port_no];
        int rc;

        /* First apply the usual rules */
        rc = ata_std_qc_defer(qc);
        if (rc != 0)
                return rc;

        /* Now apply serialization rules. Only allow a command if the
           other channel state machine is idle */
        if (alt && alt->qc_active)
                return  ATA_DEFER_PORT;
        return 0;
}

static struct scsi_host_template sl82c105_sht = {
        ATA_BMDMA_SHT(DRV_NAME),
};

static struct ata_port_operations sl82c105_port_ops = {
        .inherits       = &ata_bmdma_port_ops,
        .qc_defer       = sl82c105_qc_defer,
        .bmdma_start    = sl82c105_bmdma_start,
        .bmdma_stop     = sl82c105_bmdma_stop,
        .cable_detect   = ata_cable_40wire,
        .set_piomode    = sl82c105_set_piomode,
        .prereset       = sl82c105_pre_reset,
};

/**
 *      sl82c105_bridge_revision        -       find bridge version
 *      @pdev: PCI device for the ATA function
 *
 *      Locates the PCI bridge associated with the ATA function and
 *      providing it is a Winbond 553 reports the revision. If it cannot
 *      find a revision or the right device it returns -1
 */

static int sl82c105_bridge_revision(struct pci_dev *pdev)
{
        struct pci_dev *bridge;

        /*
         * The bridge should be part of the same device, but function 0.
         */
        bridge = pci_get_slot(pdev->bus,
                               PCI_DEVFN(PCI_SLOT(pdev->devfn), 0));
        if (!bridge)
                return -1;

        /*
         * Make sure it is a Winbond 553 and is an ISA bridge.
         */
        if (bridge->vendor != PCI_VENDOR_ID_WINBOND ||
            bridge->device != PCI_DEVICE_ID_WINBOND_83C553 ||
            bridge->class >> 8 != PCI_CLASS_BRIDGE_ISA) {
                pci_dev_put(bridge);
                return -1;
        }
        /*
         * We need to find function 0's revision, not function 1
         */
        pci_dev_put(bridge);
        return bridge->revision;
}


static int sl82c105_init_one(struct pci_dev *dev, const struct pci_device_id *id)
{
        static const struct ata_port_info info_dma = {
                .flags = ATA_FLAG_SLAVE_POSS,
                .pio_mask = ATA_PIO4,
                .mwdma_mask = ATA_MWDMA2,
                .port_ops = &sl82c105_port_ops
        };
        static const struct ata_port_info info_early = {
                .flags = ATA_FLAG_SLAVE_POSS,
                .pio_mask = ATA_PIO4,
                .port_ops = &sl82c105_port_ops
        };
        /* for now use only the first port */
        const struct ata_port_info *ppi[] = { &info_early,
                                               NULL };
        u32 val;
        int rev;
        int rc;

        rc = pcim_enable_device(dev);
        if (rc)
                return rc;

        rev = sl82c105_bridge_revision(dev);

        if (rev == -1)
                dev_printk(KERN_WARNING, &dev->dev, "pata_sl82c105: Unable to find bridge, disabling DMA.\n");
        else if (rev <= 5)
                dev_printk(KERN_WARNING, &dev->dev, "pata_sl82c105: Early bridge revision, no DMA available.\n");
        else
                ppi[0] = &info_dma;

        pci_read_config_dword(dev, 0x40, &val);
        val |= CTRL_P0EN | CTRL_P0F16 | CTRL_P1F16;
        pci_write_config_dword(dev, 0x40, val);

        return ata_pci_sff_init_one(dev, ppi, &sl82c105_sht, NULL);
}

static const struct pci_device_id sl82c105[] = {
        { PCI_VDEVICE(WINBOND, PCI_DEVICE_ID_WINBOND_82C105), },

        { },
};

static struct pci_driver sl82c105_pci_driver = {
        .name           = DRV_NAME,
        .id_table       = sl82c105,
        .probe          = sl82c105_init_one,
        .remove         = ata_pci_remove_one
};

static int __init sl82c105_init(void)
{
        return pci_register_driver(&sl82c105_pci_driver);
}

static void __exit sl82c105_exit(void)
{
        pci_unregister_driver(&sl82c105_pci_driver);
}

MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("low-level driver for Sl82c105");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(pci, sl82c105);
MODULE_VERSION(DRV_VERSION);

module_init(sl82c105_init);
module_exit(sl82c105_exit);