/*
 *  pdc_adma.c - Pacific Digital Corporation ADMA
 *
 *  Maintained by:  Mark Lord <mlord@pobox.com>
 *
 *  Copyright 2005 Mark Lord
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 *
 *  Supports ATA disks in single-packet ADMA mode.
 *  Uses PIO for everything else.
 *
 *  TODO:  Use ADMA transfers for ATAPI devices, when possible.
 *  This requires careful attention to a number of quirks of the chip.
 *
 */

#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 <linux/interrupt.h>
#include <linux/device.h>
#include <scsi/scsi_host.h>
#include <linux/libata.h>

#define DRV_NAME        "pdc_adma"
#define DRV_VERSION     "1.0"

/* macro to calculate base address for ATA regs */
#define ADMA_ATA_REGS(base, port_no)    ((base) + ((port_no) * 0x40))

/* macro to calculate base address for ADMA regs */
#define ADMA_REGS(base, port_no)        ((base) + 0x80 + ((port_no) * 0x20))

/* macro to obtain addresses from ata_port */
#define ADMA_PORT_REGS(ap) \
        ADMA_REGS((ap)->host->iomap[ADMA_MMIO_BAR], ap->port_no)

enum {
        ADMA_MMIO_BAR           = 4,

        ADMA_PORTS              = 2,
        ADMA_CPB_BYTES          = 40,
        ADMA_PRD_BYTES          = LIBATA_MAX_PRD * 16,
        ADMA_PKT_BYTES          = ADMA_CPB_BYTES + ADMA_PRD_BYTES,

        ADMA_DMA_BOUNDARY       = 0xffffffff,

        /* global register offsets */
        ADMA_MODE_LOCK          = 0x00c7,

        /* per-channel register offsets */
        ADMA_CONTROL            = 0x0000, /* ADMA control */
        ADMA_STATUS             = 0x0002, /* ADMA status */
        ADMA_CPB_COUNT          = 0x0004, /* CPB count */
        ADMA_CPB_CURRENT        = 0x000c, /* current CPB address */
        ADMA_CPB_NEXT           = 0x000c, /* next CPB address */
        ADMA_CPB_LOOKUP         = 0x0010, /* CPB lookup table */
        ADMA_FIFO_IN            = 0x0014, /* input FIFO threshold */
        ADMA_FIFO_OUT           = 0x0016, /* output FIFO threshold */

        /* ADMA_CONTROL register bits */
        aNIEN                   = (1 << 8), /* irq mask: 1==masked */
        aGO                     = (1 << 7), /* packet trigger ("Go!") */
        aRSTADM                 = (1 << 5), /* ADMA logic reset */
        aPIOMD4                 = 0x0003,   /* PIO mode 4 */

        /* ADMA_STATUS register bits */
        aPSD                    = (1 << 6),
        aUIRQ                   = (1 << 4),
        aPERR                   = (1 << 0),

        /* CPB bits */
        cDONE                   = (1 << 0),
        cATERR                  = (1 << 3),

        cVLD                    = (1 << 0),
        cDAT                    = (1 << 2),
        cIEN                    = (1 << 3),

        /* PRD bits */
        pORD                    = (1 << 4),
        pDIRO                   = (1 << 5),
        pEND                    = (1 << 7),

        /* ATA register flags */
        rIGN                    = (1 << 5),
        rEND                    = (1 << 7),

        /* ATA register addresses */
        ADMA_REGS_CONTROL       = 0x0e,
        ADMA_REGS_SECTOR_COUNT  = 0x12,
        ADMA_REGS_LBA_LOW       = 0x13,
        ADMA_REGS_LBA_MID       = 0x14,
        ADMA_REGS_LBA_HIGH      = 0x15,
        ADMA_REGS_DEVICE        = 0x16,
        ADMA_REGS_COMMAND       = 0x17,

        /* PCI device IDs */
        board_1841_idx          = 0,    /* ADMA 2-port controller */
};

typedef enum { adma_state_idle, adma_state_pkt, adma_state_mmio } adma_state_t;

struct adma_port_priv {
        u8                      *pkt;
        dma_addr_t              pkt_dma;
        adma_state_t            state;
};

static int adma_ata_init_one(struct pci_dev *pdev,
                                const struct pci_device_id *ent);
static int adma_port_start(struct ata_port *ap);
static void adma_port_stop(struct ata_port *ap);
static void adma_qc_prep(struct ata_queued_cmd *qc);
static unsigned int adma_qc_issue(struct ata_queued_cmd *qc);
static int adma_check_atapi_dma(struct ata_queued_cmd *qc);
static void adma_freeze(struct ata_port *ap);
static void adma_thaw(struct ata_port *ap);
static int adma_prereset(struct ata_link *link, unsigned long deadline);

static struct scsi_host_template adma_ata_sht = {
        ATA_BASE_SHT(DRV_NAME),
        .sg_tablesize           = LIBATA_MAX_PRD,
        .dma_boundary           = ADMA_DMA_BOUNDARY,
};

static struct ata_port_operations adma_ata_ops = {
        .inherits               = &ata_sff_port_ops,

        .check_atapi_dma        = adma_check_atapi_dma,
        .qc_prep                = adma_qc_prep,
        .qc_issue               = adma_qc_issue,

        .freeze                 = adma_freeze,
        .thaw                   = adma_thaw,
        .prereset               = adma_prereset,

        .port_start             = adma_port_start,
        .port_stop              = adma_port_stop,
};

static struct ata_port_info adma_port_info[] = {
        /* board_1841_idx */
        {
                .flags          = ATA_FLAG_SLAVE_POSS |
                                  ATA_FLAG_NO_LEGACY | ATA_FLAG_MMIO |
                                  ATA_FLAG_PIO_POLLING,
                .pio_mask       = 0x10, /* pio4 */
                .udma_mask      = ATA_UDMA4,
                .port_ops       = &adma_ata_ops,
        },
};

static const struct pci_device_id adma_ata_pci_tbl[] = {
        { PCI_VDEVICE(PDC, 0x1841), board_1841_idx },

        { }     /* terminate list */
};

static struct pci_driver adma_ata_pci_driver = {
        .name                   = DRV_NAME,
        .id_table               = adma_ata_pci_tbl,
        .probe                  = adma_ata_init_one,
        .remove                 = ata_pci_remove_one,
};

static int adma_check_atapi_dma(struct ata_queued_cmd *qc)
{
        return 1;       /* ATAPI DMA not yet supported */
}

static void adma_reset_engine(struct ata_port *ap)
{
        void __iomem *chan = ADMA_PORT_REGS(ap);

        /* reset ADMA to idle state */
        writew(aPIOMD4 | aNIEN | aRSTADM, chan + ADMA_CONTROL);
        udelay(2);
        writew(aPIOMD4, chan + ADMA_CONTROL);
        udelay(2);
}

static void adma_reinit_engine(struct ata_port *ap)
{
        struct adma_port_priv *pp = ap->private_data;
        void __iomem *chan = ADMA_PORT_REGS(ap);

        /* mask/clear ATA interrupts */
        writeb(ATA_NIEN, ap->ioaddr.ctl_addr);
        ata_sff_check_status(ap);

        /* reset the ADMA engine */
        adma_reset_engine(ap);

        /* set in-FIFO threshold to 0x100 */
        writew(0x100, chan + ADMA_FIFO_IN);

        /* set CPB pointer */
        writel((u32)pp->pkt_dma, chan + ADMA_CPB_NEXT);

        /* set out-FIFO threshold to 0x100 */
        writew(0x100, chan + ADMA_FIFO_OUT);

        /* set CPB count */
        writew(1, chan + ADMA_CPB_COUNT);

        /* read/discard ADMA status */
        readb(chan + ADMA_STATUS);
}

static inline void adma_enter_reg_mode(struct ata_port *ap)
{
        void __iomem *chan = ADMA_PORT_REGS(ap);

        writew(aPIOMD4, chan + ADMA_CONTROL);
        readb(chan + ADMA_STATUS);      /* flush */
}

static void adma_freeze(struct ata_port *ap)
{
        void __iomem *chan = ADMA_PORT_REGS(ap);

        /* mask/clear ATA interrupts */
        writeb(ATA_NIEN, ap->ioaddr.ctl_addr);
        ata_sff_check_status(ap);

        /* reset ADMA to idle state */
        writew(aPIOMD4 | aNIEN | aRSTADM, chan + ADMA_CONTROL);
        udelay(2);
        writew(aPIOMD4 | aNIEN, chan + ADMA_CONTROL);
        udelay(2);
}

static void adma_thaw(struct ata_port *ap)
{
        adma_reinit_engine(ap);
}

static int adma_prereset(struct ata_link *link, unsigned long deadline)
{
        struct ata_port *ap = link->ap;
        struct adma_port_priv *pp = ap->private_data;

        if (pp->state != adma_state_idle) /* healthy paranoia */
                pp->state = adma_state_mmio;
        adma_reinit_engine(ap);

        return ata_sff_prereset(link, deadline);
}

static int adma_fill_sg(struct ata_queued_cmd *qc)
{
        struct scatterlist *sg;
        struct ata_port *ap = qc->ap;
        struct adma_port_priv *pp = ap->private_data;
        u8  *buf = pp->pkt, *last_buf = NULL;
        int i = (2 + buf[3]) * 8;
        u8 pFLAGS = pORD | ((qc->tf.flags & ATA_TFLAG_WRITE) ? pDIRO : 0);
        unsigned int si;

        for_each_sg(qc->sg, sg, qc->n_elem, si) {
                u32 addr;
                u32 len;

                addr = (u32)sg_dma_address(sg);
                *(__le32 *)(buf + i) = cpu_to_le32(addr);
                i += 4;

                len = sg_dma_len(sg) >> 3;
                *(__le32 *)(buf + i) = cpu_to_le32(len);
                i += 4;

                last_buf = &buf[i];
                buf[i++] = pFLAGS;
                buf[i++] = qc->dev->dma_mode & 0xf;
                buf[i++] = 0;   /* pPKLW */
                buf[i++] = 0;   /* reserved */

                *(__le32 *)(buf + i) =
                        (pFLAGS & pEND) ? 0 : cpu_to_le32(pp->pkt_dma + i + 4);
                i += 4;

                VPRINTK("PRD[%u] = (0x%lX, 0x%X)\n", i/4,
                                        (unsigned long)addr, len);
        }

        if (likely(last_buf))
                *last_buf |= pEND;

        return i;
}

static void adma_qc_prep(struct ata_queued_cmd *qc)
{
        struct adma_port_priv *pp = qc->ap->private_data;
        u8  *buf = pp->pkt;
        u32 pkt_dma = (u32)pp->pkt_dma;
        int i = 0;

        VPRINTK("ENTER\n");

        adma_enter_reg_mode(qc->ap);
        if (qc->tf.protocol != ATA_PROT_DMA) {
                ata_sff_qc_prep(qc);
                return;
        }

        buf[i++] = 0;   /* Response flags */
        buf[i++] = 0;   /* reserved */
        buf[i++] = cVLD | cDAT | cIEN;
        i++;            /* cLEN, gets filled in below */

        *(__le32 *)(buf+i) = cpu_to_le32(pkt_dma);      /* cNCPB */
        i += 4;         /* cNCPB */
        i += 4;         /* cPRD, gets filled in below */

        buf[i++] = 0;   /* reserved */
        buf[i++] = 0;   /* reserved */
        buf[i++] = 0;   /* reserved */
        buf[i++] = 0;   /* reserved */

        /* ATA registers; must be a multiple of 4 */
        buf[i++] = qc->tf.device;
        buf[i++] = ADMA_REGS_DEVICE;
        if ((qc->tf.flags & ATA_TFLAG_LBA48)) {
                buf[i++] = qc->tf.hob_nsect;
                buf[i++] = ADMA_REGS_SECTOR_COUNT;
                buf[i++] = qc->tf.hob_lbal;
                buf[i++] = ADMA_REGS_LBA_LOW;
                buf[i++] = qc->tf.hob_lbam;
                buf[i++] = ADMA_REGS_LBA_MID;
                buf[i++] = qc->tf.hob_lbah;
                buf[i++] = ADMA_REGS_LBA_HIGH;
        }
        buf[i++] = qc->tf.nsect;
        buf[i++] = ADMA_REGS_SECTOR_COUNT;
        buf[i++] = qc->tf.lbal;
        buf[i++] = ADMA_REGS_LBA_LOW;
        buf[i++] = qc->tf.lbam;
        buf[i++] = ADMA_REGS_LBA_MID;
        buf[i++] = qc->tf.lbah;
        buf[i++] = ADMA_REGS_LBA_HIGH;
        buf[i++] = 0;
        buf[i++] = ADMA_REGS_CONTROL;
        buf[i++] = rIGN;
        buf[i++] = 0;
        buf[i++] = qc->tf.command;
        buf[i++] = ADMA_REGS_COMMAND | rEND;

        buf[3] = (i >> 3) - 2;                          /* cLEN */
        *(__le32 *)(buf+8) = cpu_to_le32(pkt_dma + i);  /* cPRD */

        i = adma_fill_sg(qc);
        wmb();  /* flush PRDs and pkt to memory */
#if 0
        /* dump out CPB + PRDs for debug */
        {
                int j, len = 0;
                static char obuf[2048];
                for (j = 0; j < i; ++j) {
                        len += sprintf(obuf+len, "%02x ", buf[j]);
                        if ((j & 7) == 7) {
                                printk("%s\n", obuf);
                                len = 0;
                        }
                }
                if (len)
                        printk("%s\n", obuf);
        }
#endif
}

static inline void adma_packet_start(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        void __iomem *chan = ADMA_PORT_REGS(ap);

        VPRINTK("ENTER, ap %p\n", ap);

        /* fire up the ADMA engine */
        writew(aPIOMD4 | aGO, chan + ADMA_CONTROL);
}

static unsigned int adma_qc_issue(struct ata_queued_cmd *qc)
{
        struct adma_port_priv *pp = qc->ap->private_data;

        switch (qc->tf.protocol) {
        case ATA_PROT_DMA:
                pp->state = adma_state_pkt;
                adma_packet_start(qc);
                return 0;

        case ATAPI_PROT_DMA:
                BUG();
                break;

        default:
                break;
        }

        pp->state = adma_state_mmio;
        return ata_sff_qc_issue(qc);
}

static inline unsigned int adma_intr_pkt(struct ata_host *host)
{
        unsigned int handled = 0, port_no;

        for (port_no = 0; port_no < host->n_ports; ++port_no) {
                struct ata_port *ap = host->ports[port_no];
                struct adma_port_priv *pp;
                struct ata_queued_cmd *qc;
                void __iomem *chan = ADMA_PORT_REGS(ap);
                u8 status = readb(chan + ADMA_STATUS);

                if (status == 0)
                        continue;
                handled = 1;
                adma_enter_reg_mode(ap);
                if (ap->flags & ATA_FLAG_DISABLED)
                        continue;
                pp = ap->private_data;
                if (!pp || pp->state != adma_state_pkt)
                        continue;
                qc = ata_qc_from_tag(ap, ap->link.active_tag);
                if (qc && (!(qc->tf.flags & ATA_TFLAG_POLLING))) {
                        if (status & aPERR)
                                qc->err_mask |= AC_ERR_HOST_BUS;
                        else if ((status & (aPSD | aUIRQ)))
                                qc->err_mask |= AC_ERR_OTHER;

                        if (pp->pkt[0] & cATERR)
                                qc->err_mask |= AC_ERR_DEV;
                        else if (pp->pkt[0] != cDONE)
                                qc->err_mask |= AC_ERR_OTHER;

                        if (!qc->err_mask)
                                ata_qc_complete(qc);
                        else {
                                struct ata_eh_info *ehi = &ap->link.eh_info;
                                ata_ehi_clear_desc(ehi);
                                ata_ehi_push_desc(ehi,
                                        "ADMA-status 0x%02X", status);
                                ata_ehi_push_desc(ehi,
                                        "pkt[0] 0x%02X", pp->pkt[0]);

                                if (qc->err_mask == AC_ERR_DEV)
                                        ata_port_abort(ap);
                                else
                                        ata_port_freeze(ap);
                        }
                }
        }
        return handled;
}

static inline unsigned int adma_intr_mmio(struct ata_host *host)
{
        unsigned int handled = 0, port_no;

        for (port_no = 0; port_no < host->n_ports; ++port_no) {
                struct ata_port *ap;
                ap = host->ports[port_no];
                if (ap && (!(ap->flags & ATA_FLAG_DISABLED))) {
                        struct ata_queued_cmd *qc;
                        struct adma_port_priv *pp = ap->private_data;
                        if (!pp || pp->state != adma_state_mmio)
                                continue;
                        qc = ata_qc_from_tag(ap, ap->link.active_tag);
                        if (qc && (!(qc->tf.flags & ATA_TFLAG_POLLING))) {

                                /* check main status, clearing INTRQ */
                                u8 status = ata_sff_check_status(ap);
                                if ((status & ATA_BUSY))
                                        continue;
                                DPRINTK("ata%u: protocol %d (dev_stat 0x%X)\n",
                                        ap->print_id, qc->tf.protocol, status);

                                /* complete taskfile transaction */
                                pp->state = adma_state_idle;
                                qc->err_mask |= ac_err_mask(status);
                                if (!qc->err_mask)
                                        ata_qc_complete(qc);
                                else {
                                        struct ata_eh_info *ehi =
                                                &ap->link.eh_info;
                                        ata_ehi_clear_desc(ehi);
                                        ata_ehi_push_desc(ehi,
                                                "status 0x%02X", status);

                                        if (qc->err_mask == AC_ERR_DEV)
                                                ata_port_abort(ap);
                                        else
                                                ata_port_freeze(ap);
                                }
                                handled = 1;
                        }
                }
        }
        return handled;
}

static irqreturn_t adma_intr(int irq, void *dev_instance)
{
        struct ata_host *host = dev_instance;
        unsigned int handled = 0;

        VPRINTK("ENTER\n");

        spin_lock(&host->lock);
        handled  = adma_intr_pkt(host) | adma_intr_mmio(host);
        spin_unlock(&host->lock);

        VPRINTK("EXIT\n");

        return IRQ_RETVAL(handled);
}

static void adma_ata_setup_port(struct ata_ioports *port, void __iomem *base)
{
        port->cmd_addr          =
        port->data_addr         = base + 0x000;
        port->error_addr        =
        port->feature_addr      = base + 0x004;
        port->nsect_addr        = base + 0x008;
        port->lbal_addr         = base + 0x00c;
        port->lbam_addr         = base + 0x010;
        port->lbah_addr         = base + 0x014;
        port->device_addr       = base + 0x018;
        port->status_addr       =
        port->command_addr      = base + 0x01c;
        port->altstatus_addr    =
        port->ctl_addr          = base + 0x038;
}

static int adma_port_start(struct ata_port *ap)
{
        struct device *dev = ap->host->dev;
        struct adma_port_priv *pp;
        int rc;

        rc = ata_port_start(ap);
        if (rc)
                return rc;
        adma_enter_reg_mode(ap);
        pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL);
        if (!pp)
                return -ENOMEM;
        pp->pkt = dmam_alloc_coherent(dev, ADMA_PKT_BYTES, &pp->pkt_dma,
                                      GFP_KERNEL);
        if (!pp->pkt)
                return -ENOMEM;
        /* paranoia? */
        if ((pp->pkt_dma & 7) != 0) {
                printk(KERN_ERR "bad alignment for pp->pkt_dma: %08x\n",
                                                (u32)pp->pkt_dma);
                return -ENOMEM;
        }
        memset(pp->pkt, 0, ADMA_PKT_BYTES);
        ap->private_data = pp;
        adma_reinit_engine(ap);
        return 0;
}

static void adma_port_stop(struct ata_port *ap)
{
        adma_reset_engine(ap);
}

static void adma_host_init(struct ata_host *host, unsigned int chip_id)
{
        unsigned int port_no;

        /* enable/lock aGO operation */
        writeb(7, host->iomap[ADMA_MMIO_BAR] + ADMA_MODE_LOCK);

        /* reset the ADMA logic */
        for (port_no = 0; port_no < ADMA_PORTS; ++port_no)
                adma_reset_engine(host->ports[port_no]);
}

static int adma_set_dma_masks(struct pci_dev *pdev, void __iomem *mmio_base)
{
        int rc;

        rc = pci_set_dma_mask(pdev, DMA_32BIT_MASK);
        if (rc) {
                dev_printk(KERN_ERR, &pdev->dev,
                        "32-bit DMA enable failed\n");
                return rc;
        }
        rc = pci_set_consistent_dma_mask(pdev, DMA_32BIT_MASK);
        if (rc) {
                dev_printk(KERN_ERR, &pdev->dev,
                        "32-bit consistent DMA enable failed\n");
                return rc;
        }
        return 0;
}

static int adma_ata_init_one(struct pci_dev *pdev,
                             const struct pci_device_id *ent)
{
        static int printed_version;
        unsigned int board_idx = (unsigned int) ent->driver_data;
        const struct ata_port_info *ppi[] = { &adma_port_info[board_idx], NULL };
        struct ata_host *host;
        void __iomem *mmio_base;
        int rc, port_no;

        if (!printed_version++)
                dev_printk(KERN_DEBUG, &pdev->dev, "version " DRV_VERSION "\n");

        /* alloc host */
        host = ata_host_alloc_pinfo(&pdev->dev, ppi, ADMA_PORTS);
        if (!host)
                return -ENOMEM;

        /* acquire resources and fill host */
        rc = pcim_enable_device(pdev);
        if (rc)
                return rc;

        if ((pci_resource_flags(pdev, 4) & IORESOURCE_MEM) == 0)
                return -ENODEV;

        rc = pcim_iomap_regions(pdev, 1 << ADMA_MMIO_BAR, DRV_NAME);
        if (rc)
                return rc;
        host->iomap = pcim_iomap_table(pdev);
        mmio_base = host->iomap[ADMA_MMIO_BAR];

        rc = adma_set_dma_masks(pdev, mmio_base);
        if (rc)
                return rc;

        for (port_no = 0; port_no < ADMA_PORTS; ++port_no) {
                struct ata_port *ap = host->ports[port_no];
                void __iomem *port_base = ADMA_ATA_REGS(mmio_base, port_no);
                unsigned int offset = port_base - mmio_base;

                adma_ata_setup_port(&ap->ioaddr, port_base);

                ata_port_pbar_desc(ap, ADMA_MMIO_BAR, -1, "mmio");
                ata_port_pbar_desc(ap, ADMA_MMIO_BAR, offset, "port");
        }

        /* initialize adapter */
        adma_host_init(host, board_idx);

        pci_set_master(pdev);
        return ata_host_activate(host, pdev->irq, adma_intr, IRQF_SHARED,
                                 &adma_ata_sht);
}

static int __init adma_ata_init(void)
{
        return pci_register_driver(&adma_ata_pci_driver);
}

static void __exit adma_ata_exit(void)
{
        pci_unregister_driver(&adma_ata_pci_driver);
}

MODULE_AUTHOR("Mark Lord");
MODULE_DESCRIPTION("Pacific Digital Corporation ADMA low-level driver");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(pci, adma_ata_pci_tbl);
MODULE_VERSION(DRV_VERSION);

module_init(adma_ata_init);
module_exit(adma_ata_exit);