// SPDX-License-Identifier: GPL-2.0-only
/*
 * New ATA layer SC1200 driver          Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 * TODO: Mode selection filtering
 * TODO: Needs custom DMA cleanup code
 *
 * Based very heavily on
 *
 * linux/drivers/ide/pci/sc1200.c               Version 0.91    28-Jan-2003
 *
 * Copyright (C) 2000-2002              Mark Lord <mlord@pobox.com>
 * 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.
 */

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

#define DRV_NAME        "pata_sc1200"
#define DRV_VERSION     "0.2.6"

#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

/**
 *      sc1200_clock    -       PCI clock
 *
 *      Return the PCI bus clocking for the SC1200 chipset configuration
 *      in use. We return 0 for 33MHz 1 for 48MHz and 2 for 66Mhz
 */

static int sc1200_clock(void)
{
        /* Magic registers that give us the chipset data */
        u8 chip_id = inb(0x903C);
        u8 silicon_rev = inb(0x903D);
        u16 pci_clock;

        if (chip_id == 0x04 && silicon_rev < SC1200_REV_B1)
                return 0;       /* 33 MHz mode */

        /* Clock generator configuration 0x901E its 8/9 are the PCI clocking
           0/3 is 33Mhz 1 is 48 2 is 66 */

        pci_clock = inw(0x901E);
        pci_clock >>= 8;
        pci_clock &= 0x03;
        if (pci_clock == 3)
                pci_clock = 0;
        return pci_clock;
}

/**
 *      sc1200_set_piomode              -       PIO setup
 *      @ap: ATA interface
 *      @adev: device on the interface
 *
 *      Set our PIO requirements. This is fairly simple on the SC1200
 */

static void sc1200_set_piomode(struct ata_port *ap, struct ata_device *adev)
{
        static const u32 pio_timings[4][5] = {
                /* format0, 33Mhz */
                { 0x00009172, 0x00012171, 0x00020080, 0x00032010, 0x00040010 },
                /* format1, 33Mhz */
                { 0xd1329172, 0x71212171, 0x30200080, 0x20102010, 0x00100010 },
                /* format1, 48Mhz */
                { 0xfaa3f4f3, 0xc23232b2, 0x513101c1, 0x31213121, 0x10211021 },
                /* format1, 66Mhz */
                { 0xfff4fff4, 0xf35353d3, 0x814102f1, 0x42314231, 0x11311131 }
        };

        struct pci_dev *pdev = to_pci_dev(ap->host->dev);
        u32 format;
        unsigned int reg = 0x40 + 0x10 * ap->port_no;
        int mode = adev->pio_mode - XFER_PIO_0;

        pci_read_config_dword(pdev, reg + 4, &format);
        format >>= 31;
        format += sc1200_clock();
        pci_write_config_dword(pdev, reg + 8 * adev->devno,
                                pio_timings[format][mode]);
}

/**
 *      sc1200_set_dmamode              -       DMA timing setup
 *      @ap: ATA interface
 *      @adev: Device being configured
 *
 *      We cannot mix MWDMA and UDMA without reloading timings each switch
 *      master to slave.
 */

static void sc1200_set_dmamode(struct ata_port *ap, struct ata_device *adev)
{
        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 }
        };

        int clock = sc1200_clock();
        struct pci_dev *pdev = to_pci_dev(ap->host->dev);
        unsigned int reg = 0x40 + 0x10 * ap->port_no;
        int mode = adev->dma_mode;
        u32 format;

        if (mode >= XFER_UDMA_0)
                format = udma_timing[clock][mode - XFER_UDMA_0];
        else
                format = mwdma_timing[clock][mode - XFER_MW_DMA_0];

        if (adev->devno == 0) {
                u32 timings;

                pci_read_config_dword(pdev, reg + 4, &timings);
                timings &= 0x80000000UL;
                timings |= format;
                pci_write_config_dword(pdev, reg + 4, timings);
        } else
                pci_write_config_dword(pdev, reg + 12, format);
}

/**
 *      sc1200_qc_issue         -       command issue
 *      @qc: command pending
 *
 *      Called when the libata layer is about to issue a command. We wrap
 *      this interface so that we can load the correct ATA timings if
 *      necessary.  Specifically we have a problem that there is only
 *      one MWDMA/UDMA bit.
 */

static unsigned int sc1200_qc_issue(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct ata_device *adev = qc->dev;
        struct ata_device *prev = ap->private_data;

        /* See if the DMA settings could be wrong */
        if (ata_dma_enabled(adev) && adev != prev && prev != NULL) {
                /* Maybe, but do the channels match MWDMA/UDMA ? */
                if ((ata_using_udma(adev) && !ata_using_udma(prev)) ||
                    (ata_using_udma(prev) && !ata_using_udma(adev)))
                        /* Switch the mode bits */
                        sc1200_set_dmamode(ap, adev);
        }

        return ata_bmdma_qc_issue(qc);
}

/**
 *      sc1200_qc_defer -       implement serialization
 *      @qc: command
 *
 *      Serialize command issue on this controller.
 */

static int sc1200_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 sc1200_sht = {
        ATA_BMDMA_SHT(DRV_NAME),
        .sg_tablesize   = LIBATA_DUMB_MAX_PRD,
};

static struct ata_port_operations sc1200_port_ops = {
        .inherits       = &ata_bmdma_port_ops,
        .qc_prep        = ata_bmdma_dumb_qc_prep,
        .qc_issue       = sc1200_qc_issue,
        .qc_defer       = sc1200_qc_defer,
        .cable_detect   = ata_cable_40wire,
        .set_piomode    = sc1200_set_piomode,
        .set_dmamode    = sc1200_set_dmamode,
};

/**
 *      sc1200_init_one         -       Initialise an SC1200
 *      @dev: PCI device
 *      @id: Entry in match table
 *
 *      Just throw the needed data at the libata helper and it does all
 *      our work.
 */

static int sc1200_init_one(struct pci_dev *dev, const struct pci_device_id *id)
{
        static const struct ata_port_info info = {
                .flags = ATA_FLAG_SLAVE_POSS,
                .pio_mask = ATA_PIO4,
                .mwdma_mask = ATA_MWDMA2,
                .udma_mask = ATA_UDMA2,
                .port_ops = &sc1200_port_ops
        };
        const struct ata_port_info *ppi[] = { &info, NULL };

        return ata_pci_bmdma_init_one(dev, ppi, &sc1200_sht, NULL, 0);
}

static const struct pci_device_id sc1200[] = {
        { PCI_VDEVICE(NS, PCI_DEVICE_ID_NS_SCx200_IDE), },

        { },
};

static struct pci_driver sc1200_pci_driver = {
        .name           = DRV_NAME,
        .id_table       = sc1200,
        .probe          = sc1200_init_one,
        .remove         = ata_pci_remove_one,
#ifdef CONFIG_PM_SLEEP
        .suspend        = ata_pci_device_suspend,
        .resume         = ata_pci_device_resume,
#endif
};

module_pci_driver(sc1200_pci_driver);

MODULE_AUTHOR("Alan Cox, Mark Lord");
MODULE_DESCRIPTION("low-level driver for the NS/AMD SC1200");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(pci, sc1200);
MODULE_VERSION(DRV_VERSION);