/*
 * Copyright (C) 2000-2002              Mark Lord <mlord@pobox.com>
 * Copyright (C)      2007              Bartlomiej Zolnierkiewicz
 *
 * May be copied or modified under the terms of the GNU General Public License
 *
 * Development of this chipset driver was funded
 * by the nice folks at National Semiconductor.
 *
 * Documentation:
 *      Available from National Semiconductor
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/ide.h>
#include <linux/pm.h>

#include <asm/io.h>

#define DRV_NAME "sc1200"

#define SC1200_REV_A    0x00
#define SC1200_REV_B1   0x01
#define SC1200_REV_B3   0x02
#define SC1200_REV_C1   0x03
#define SC1200_REV_D1   0x04

#define PCI_CLK_33      0x00
#define PCI_CLK_48      0x01
#define PCI_CLK_66      0x02
#define PCI_CLK_33A     0x03

static unsigned short sc1200_get_pci_clock (void)
{
        unsigned char chip_id, silicon_revision;
        unsigned int pci_clock;
        /*
         * Check the silicon revision, as not all versions of the chip
         * have the register with the fast PCI bus timings.
         */
        chip_id = inb (0x903c);
        silicon_revision = inb (0x903d);

        // Read the fast pci clock frequency
        if (chip_id == 0x04 && silicon_revision < SC1200_REV_B1) {
                pci_clock = PCI_CLK_33;
        } else {
                // check clock generator configuration (cfcc)
                // the clock is in bits 8 and 9 of this word

                pci_clock = inw (0x901e);
                pci_clock >>= 8;
                pci_clock &= 0x03;
                if (pci_clock == PCI_CLK_33A)
                        pci_clock = PCI_CLK_33;
        }
        return pci_clock;
}

/*
 * Here are the standard PIO mode 0-4 timings for each "format".
 * Format-0 uses fast data reg timings, with slower command reg timings.
 * Format-1 uses fast timings for all registers, but won't work with all drives.
 */
static const unsigned int sc1200_pio_timings[4][5] =
        {{0x00009172, 0x00012171, 0x00020080, 0x00032010, 0x00040010},  // format0  33Mhz
         {0xd1329172, 0x71212171, 0x30200080, 0x20102010, 0x00100010},  // format1, 33Mhz
         {0xfaa3f4f3, 0xc23232b2, 0x513101c1, 0x31213121, 0x10211021},  // format1, 48Mhz
         {0xfff4fff4, 0xf35353d3, 0x814102f1, 0x42314231, 0x11311131}}; // format1, 66Mhz

/*
 * After chip reset, the PIO timings are set to 0x00009172, which is not valid.
 */
//#define SC1200_BAD_PIO(timings) (((timings)&~0x80000000)==0x00009172)

static void sc1200_tunepio(ide_drive_t *drive, u8 pio)
{
        ide_hwif_t *hwif = drive->hwif;
        struct pci_dev *pdev = to_pci_dev(hwif->dev);
        unsigned int basereg = hwif->channel ? 0x50 : 0x40, format = 0;

        pci_read_config_dword(pdev, basereg + 4, &format);
        format = (format >> 31) & 1;
        if (format)
                format += sc1200_get_pci_clock();
        pci_write_config_dword(pdev, basereg + ((drive->dn & 1) << 3),
                               sc1200_pio_timings[format][pio]);
}

/*
 *      The SC1200 specifies that two drives sharing a cable cannot mix
 *      UDMA/MDMA.  It has to be one or the other, for the pair, though
 *      different timings can still be chosen for each drive.  We could
 *      set the appropriate timing bits on the fly, but that might be
 *      a bit confusing.  So, for now we statically handle this requirement
 *      by looking at our mate drive to see what it is capable of, before
 *      choosing a mode for our own drive.
 */
static u8 sc1200_udma_filter(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        ide_drive_t *mate = ide_get_pair_dev(drive);
        u16 *mateid;
        u8 mask = hwif->ultra_mask;

        if (mate == NULL)
                goto out;
        mateid = mate->id;

        if (ata_id_has_dma(mateid) && __ide_dma_bad_drive(mate) == 0) {
                if ((mateid[ATA_ID_FIELD_VALID] & 4) &&
                    (mateid[ATA_ID_UDMA_MODES] & 7))
                        goto out;
                if (mateid[ATA_ID_MWDMA_MODES] & 7)
                        mask = 0;
        }
out:
        return mask;
}

static void sc1200_set_dma_mode(ide_hwif_t *hwif, ide_drive_t *drive)
{
        struct pci_dev          *dev = to_pci_dev(hwif->dev);
        unsigned int            reg, timings;
        unsigned short          pci_clock;
        unsigned int            basereg = hwif->channel ? 0x50 : 0x40;
        const u8                mode = drive->dma_mode;

        static const u32 udma_timing[3][3] = {
                { 0x00921250, 0x00911140, 0x00911030 },
                { 0x00932470, 0x00922260, 0x00922140 },
                { 0x009436a1, 0x00933481, 0x00923261 },
        };

        static const u32 mwdma_timing[3][3] = {
                { 0x00077771, 0x00012121, 0x00002020 },
                { 0x000bbbb2, 0x00024241, 0x00013131 },
                { 0x000ffff3, 0x00035352, 0x00015151 },
        };

        pci_clock = sc1200_get_pci_clock();

        /*
         * Note that each DMA mode has several timings associated with it.
         * The correct timing depends on the fast PCI clock freq.
         */

        if (mode >= XFER_UDMA_0)
                timings =  udma_timing[pci_clock][mode - XFER_UDMA_0];
        else
                timings = mwdma_timing[pci_clock][mode - XFER_MW_DMA_0];

        if ((drive->dn & 1) == 0) {
                pci_read_config_dword(dev, basereg + 4, &reg);
                timings |= reg & 0x80000000;    /* preserve PIO format bit */
                pci_write_config_dword(dev, basereg + 4, timings);
        } else
                pci_write_config_dword(dev, basereg + 12, timings);
}

/*  Replacement for the standard ide_dma_end action in
 *  dma_proc.
 *
 *  returns 1 on error, 0 otherwise
 */
static int sc1200_dma_end(ide_drive_t *drive)
{
        ide_hwif_t *hwif = drive->hwif;
        unsigned long dma_base = hwif->dma_base;
        u8 dma_stat;

        dma_stat = inb(dma_base+2);             /* get DMA status */

        if (!(dma_stat & 4))
                printk(" ide_dma_end dma_stat=%0x err=%x newerr=%x\n",
                  dma_stat, ((dma_stat&7)!=4), ((dma_stat&2)==2));

        outb(dma_stat|0x1b, dma_base+2);        /* clear the INTR & ERROR bits */
        outb(inb(dma_base)&~1, dma_base);       /* !! DO THIS HERE !! stop DMA */

        return (dma_stat & 7) != 4;             /* verify good DMA status */
}

/*
 * sc1200_set_pio_mode() handles setting of PIO modes
 * for both the chipset and drive.
 *
 * All existing BIOSs for this chipset guarantee that all drives
 * will have valid default PIO timings set up before we get here.
 */

static void sc1200_set_pio_mode(ide_hwif_t *hwif, ide_drive_t *drive)
{
        int             mode = -1;
        const u8        pio = drive->pio_mode - XFER_PIO_0;

        /*
         * bad abuse of ->set_pio_mode interface
         */
        switch (pio) {
                case 200: mode = XFER_UDMA_0;   break;
                case 201: mode = XFER_UDMA_1;   break;
                case 202: mode = XFER_UDMA_2;   break;
                case 100: mode = XFER_MW_DMA_0; break;
                case 101: mode = XFER_MW_DMA_1; break;
                case 102: mode = XFER_MW_DMA_2; break;
        }
        if (mode != -1) {
                printk("SC1200: %s: changing (U)DMA mode\n", drive->name);
                ide_dma_off_quietly(drive);
                if (ide_set_dma_mode(drive, mode) == 0 &&
                    (drive->dev_flags & IDE_DFLAG_USING_DMA))
                        hwif->dma_ops->dma_host_set(drive, 1);
                return;
        }

        sc1200_tunepio(drive, pio);
}

#ifdef CONFIG_PM
struct sc1200_saved_state {
        u32 regs[8];
};

static int sc1200_suspend (struct pci_dev *dev, pm_message_t state)
{
        printk("SC1200: suspend(%u)\n", state.event);

        /*
         * we only save state when going from full power to less
         */
        if (state.event == PM_EVENT_ON) {
                struct ide_host *host = pci_get_drvdata(dev);
                struct sc1200_saved_state *ss = host->host_priv;
                unsigned int r;

                /*
                 * save timing registers
                 * (this may be unnecessary if BIOS also does it)
                 */
                for (r = 0; r < 8; r++)
                        pci_read_config_dword(dev, 0x40 + r * 4, &ss->regs[r]);
        }

        pci_disable_device(dev);
        pci_set_power_state(dev, pci_choose_state(dev, state));
        return 0;
}

static int sc1200_resume (struct pci_dev *dev)
{
        struct ide_host *host = pci_get_drvdata(dev);
        struct sc1200_saved_state *ss = host->host_priv;
        unsigned int r;
        int i;

        i = pci_enable_device(dev);
        if (i)
                return i;

        /*
         * restore timing registers
         * (this may be unnecessary if BIOS also does it)
         */
        for (r = 0; r < 8; r++)
                pci_write_config_dword(dev, 0x40 + r * 4, ss->regs[r]);

        return 0;
}
#endif

static const struct ide_port_ops sc1200_port_ops = {
        .set_pio_mode           = sc1200_set_pio_mode,
        .set_dma_mode           = sc1200_set_dma_mode,
        .udma_filter            = sc1200_udma_filter,
};

static const struct ide_dma_ops sc1200_dma_ops = {
        .dma_host_set           = ide_dma_host_set,
        .dma_setup              = ide_dma_setup,
        .dma_start              = ide_dma_start,
        .dma_end                = sc1200_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,
};

static const struct ide_port_info sc1200_chipset = {
        .name           = DRV_NAME,
        .port_ops       = &sc1200_port_ops,
        .dma_ops        = &sc1200_dma_ops,
        .host_flags     = IDE_HFLAG_SERIALIZE |
                          IDE_HFLAG_POST_SET_MODE |
                          IDE_HFLAG_ABUSE_DMA_MODES,
        .pio_mask       = ATA_PIO4,
        .mwdma_mask     = ATA_MWDMA2,
        .udma_mask      = ATA_UDMA2,
};

static int sc1200_init_one(struct pci_dev *dev, const struct pci_device_id *id)
{
        struct sc1200_saved_state *ss = NULL;
        int rc;

#ifdef CONFIG_PM
        ss = kmalloc(sizeof(*ss), GFP_KERNEL);
        if (ss == NULL)
                return -ENOMEM;
#endif
        rc = ide_pci_init_one(dev, &sc1200_chipset, ss);
        if (rc)
                kfree(ss);

        return rc;
}

static const struct pci_device_id sc1200_pci_tbl[] = {
        { PCI_VDEVICE(NS, PCI_DEVICE_ID_NS_SCx200_IDE), 0},
        { 0, },
};
MODULE_DEVICE_TABLE(pci, sc1200_pci_tbl);

static struct pci_driver sc1200_pci_driver = {
        .name           = "SC1200_IDE",
        .id_table       = sc1200_pci_tbl,
        .probe          = sc1200_init_one,
        .remove         = ide_pci_remove,
#ifdef CONFIG_PM
        .suspend        = sc1200_suspend,
        .resume         = sc1200_resume,
#endif
};

static int __init sc1200_ide_init(void)
{
        return ide_pci_register_driver(&sc1200_pci_driver);
}

static void __exit sc1200_ide_exit(void)
{
        pci_unregister_driver(&sc1200_pci_driver);
}

module_init(sc1200_ide_init);
module_exit(sc1200_ide_exit);

MODULE_AUTHOR("Mark Lord");
MODULE_DESCRIPTION("PCI driver module for NS SC1200 IDE");
MODULE_LICENSE("GPL");