/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
 * Copyright (C) 1999 Andrew R. Baker (andrewb@uab.edu)
 * Copyright (C) 2001 Florian Lohoff (flo@rfc822.org)
 * Copyright (C) 2003, 07 Ralf Baechle (ralf@linux-mips.org)
 * 
 * (In all truth, Jed Schimmel wrote all this code.)
 */

#undef DEBUG

#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/gfp.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

#include <asm/sgi/hpc3.h>
#include <asm/sgi/ip22.h>
#include <asm/sgi/wd.h>

#include "scsi.h"
#include "wd33c93.h"

struct ip22_hostdata {
        struct WD33C93_hostdata wh;
        dma_addr_t dma;
        void *cpu;
        struct device *dev;
};

#define host_to_hostdata(host) ((struct ip22_hostdata *)((host)->hostdata))

struct hpc_chunk {
        struct hpc_dma_desc desc;
        u32 _padding;   /* align to quadword boundary */
};

/* space for hpc dma descriptors */
#define HPC_DMA_SIZE   PAGE_SIZE

#define DMA_DIR(d)   ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)

static irqreturn_t sgiwd93_intr(int irq, void *dev_id)
{
        struct Scsi_Host * host = dev_id;
        unsigned long flags;

        spin_lock_irqsave(host->host_lock, flags);
        wd33c93_intr(host);
        spin_unlock_irqrestore(host->host_lock, flags);

        return IRQ_HANDLED;
}

static inline
void fill_hpc_entries(struct ip22_hostdata *hd, struct scsi_cmnd *cmd, int din)
{
        unsigned long len = cmd->SCp.this_residual;
        void *addr = cmd->SCp.ptr;
        dma_addr_t physaddr;
        unsigned long count;
        struct hpc_chunk *hcp;

        physaddr = dma_map_single(hd->dev, addr, len, DMA_DIR(din));
        cmd->SCp.dma_handle = physaddr;
        hcp = hd->cpu;

        while (len) {
                /*
                 * even cntinfo could be up to 16383, without
                 * magic only 8192 works correctly
                 */
                count = len > 8192 ? 8192 : len;
                hcp->desc.pbuf = physaddr;
                hcp->desc.cntinfo = count;
                hcp++;
                len -= count;
                physaddr += count;
        }

        /*
         * To make sure, if we trip an HPC bug, that we transfer every single
         * byte, we tag on an extra zero length dma descriptor at the end of
         * the chain.
         */
        hcp->desc.pbuf = 0;
        hcp->desc.cntinfo = HPCDMA_EOX;
        dma_cache_sync(hd->dev, hd->cpu,
                       (unsigned long)(hcp + 1) - (unsigned long)hd->cpu,
                       DMA_TO_DEVICE);
}

static int dma_setup(struct scsi_cmnd *cmd, int datainp)
{
        struct ip22_hostdata *hdata = host_to_hostdata(cmd->device->host);
        struct hpc3_scsiregs *hregs =
                (struct hpc3_scsiregs *) cmd->device->host->base;

        pr_debug("dma_setup: datainp<%d> hcp<%p> ", datainp, hdata->cpu);

        hdata->wh.dma_dir = datainp;

        /*
         * wd33c93 shouldn't pass us bogus dma_setups, but it does:-(  The
         * other wd33c93 drivers deal with it the same way (which isn't that
         * obvious).  IMHO a better fix would be, not to do these dma setups
         * in the first place.
         */
        if (cmd->SCp.ptr == NULL || cmd->SCp.this_residual == 0)
                return 1;

        fill_hpc_entries(hdata, cmd, datainp);

        pr_debug(" HPCGO\n");

        /* Start up the HPC. */
        hregs->ndptr = hdata->dma;
        if (datainp)
                hregs->ctrl = HPC3_SCTRL_ACTIVE;
        else
                hregs->ctrl = HPC3_SCTRL_ACTIVE | HPC3_SCTRL_DIR;

        return 0;
}

static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
                     int status)
{
        struct ip22_hostdata *hdata = host_to_hostdata(instance);
        struct hpc3_scsiregs *hregs;

        if (!SCpnt)
                return;

        if (SCpnt->SCp.ptr == NULL || SCpnt->SCp.this_residual == 0)
                return;

        hregs = (struct hpc3_scsiregs *) SCpnt->device->host->base;

        pr_debug("dma_stop: status<%d> ", status);

        /* First stop the HPC and flush it's FIFO. */
        if (hdata->wh.dma_dir) {
                hregs->ctrl |= HPC3_SCTRL_FLUSH;
                while (hregs->ctrl & HPC3_SCTRL_ACTIVE)
                        barrier();
        }
        hregs->ctrl = 0;
        dma_unmap_single(hdata->dev, SCpnt->SCp.dma_handle,
                         SCpnt->SCp.this_residual,
                         DMA_DIR(hdata->wh.dma_dir));

        pr_debug("\n");
}

void sgiwd93_reset(unsigned long base)
{
        struct hpc3_scsiregs *hregs = (struct hpc3_scsiregs *) base;

        hregs->ctrl = HPC3_SCTRL_CRESET;
        udelay(50);
        hregs->ctrl = 0;
}
EXPORT_SYMBOL_GPL(sgiwd93_reset);

static inline void init_hpc_chain(struct ip22_hostdata *hdata)
{
        struct hpc_chunk *hcp = (struct hpc_chunk *)hdata->cpu;
        dma_addr_t dma = hdata->dma;
        unsigned long start, end;

        start = (unsigned long) hcp;
        end = start + HPC_DMA_SIZE;
        while (start < end) {
                hcp->desc.pnext = (u32) (dma + sizeof(struct hpc_chunk));
                hcp->desc.cntinfo = HPCDMA_EOX;
                hcp++;
                dma += sizeof(struct hpc_chunk);
                start += sizeof(struct hpc_chunk);
        };
        hcp--;
        hcp->desc.pnext = hdata->dma;
}

static int sgiwd93_bus_reset(struct scsi_cmnd *cmd)
{
        /* FIXME perform bus-specific reset */

        /* FIXME 2: kill this function, and let midlayer fallback
           to the same result, calling wd33c93_host_reset() */

        spin_lock_irq(cmd->device->host->host_lock);
        wd33c93_host_reset(cmd);
        spin_unlock_irq(cmd->device->host->host_lock);

        return SUCCESS;
}

/*
 * Kludge alert - the SCSI code calls the abort and reset method with int
 * arguments not with pointers.  So this is going to blow up beautyfully
 * on 64-bit systems with memory outside the compat address spaces.
 */
static struct scsi_host_template sgiwd93_template = {
        .module                 = THIS_MODULE,
        .proc_name              = "SGIWD93",
        .name                   = "SGI WD93",
        .queuecommand           = wd33c93_queuecommand,
        .eh_abort_handler       = wd33c93_abort,
        .eh_bus_reset_handler   = sgiwd93_bus_reset,
        .eh_host_reset_handler  = wd33c93_host_reset,
        .can_queue              = 16,
        .this_id                = 7,
        .sg_tablesize           = SG_ALL,
        .cmd_per_lun            = 8,
        .use_clustering         = DISABLE_CLUSTERING,
};

static int sgiwd93_probe(struct platform_device *pdev)
{
        struct sgiwd93_platform_data *pd = pdev->dev.platform_data;
        unsigned char *wdregs = pd->wdregs;
        struct hpc3_scsiregs *hregs = pd->hregs;
        struct ip22_hostdata *hdata;
        struct Scsi_Host *host;
        wd33c93_regs regs;
        unsigned int unit = pd->unit;
        unsigned int irq = pd->irq;
        int err;

        host = scsi_host_alloc(&sgiwd93_template, sizeof(struct ip22_hostdata));
        if (!host) {
                err = -ENOMEM;
                goto out;
        }

        host->base = (unsigned long) hregs;
        host->irq = irq;

        hdata = host_to_hostdata(host);
        hdata->dev = &pdev->dev;
        hdata->cpu = dma_alloc_noncoherent(&pdev->dev, HPC_DMA_SIZE,
                                           &hdata->dma, GFP_KERNEL);
        if (!hdata->cpu) {
                printk(KERN_WARNING "sgiwd93: Could not allocate memory for "
                       "host %d buffer.\n", unit);
                err = -ENOMEM;
                goto out_put;
        }

        init_hpc_chain(hdata);

        regs.SASR = wdregs + 3;
        regs.SCMD = wdregs + 7;

        hdata->wh.no_sync = 0;
        hdata->wh.fast = 1;
        hdata->wh.dma_mode = CTRL_BURST;

        wd33c93_init(host, regs, dma_setup, dma_stop, WD33C93_FS_MHZ(20));

        err = request_irq(irq, sgiwd93_intr, 0, "SGI WD93", host);
        if (err) {
                printk(KERN_WARNING "sgiwd93: Could not register irq %d "
                       "for host %d.\n", irq, unit);
                goto out_free;
        }

        platform_set_drvdata(pdev, host);

        err = scsi_add_host(host, NULL);
        if (err)
                goto out_irq;

        scsi_scan_host(host);

        return 0;

out_irq:
        free_irq(irq, host);
out_free:
        dma_free_noncoherent(&pdev->dev, HPC_DMA_SIZE, hdata->cpu, hdata->dma);
out_put:
        scsi_host_put(host);
out:

        return err;
}

static int __exit sgiwd93_remove(struct platform_device *pdev)
{
        struct Scsi_Host *host = platform_get_drvdata(pdev);
        struct ip22_hostdata *hdata = (struct ip22_hostdata *) host->hostdata;
        struct sgiwd93_platform_data *pd = pdev->dev.platform_data;

        scsi_remove_host(host);
        free_irq(pd->irq, host);
        dma_free_noncoherent(&pdev->dev, HPC_DMA_SIZE, hdata->cpu, hdata->dma);
        scsi_host_put(host);
        return 0;
}

static struct platform_driver sgiwd93_driver = {
        .probe  = sgiwd93_probe,
        .remove = sgiwd93_remove,
        .driver = {
                .name   = "sgiwd93",
                .owner  = THIS_MODULE,
        }
};

static int __init sgiwd93_module_init(void)
{
        return platform_driver_register(&sgiwd93_driver);
}

static void __exit sgiwd93_module_exit(void)
{
        return platform_driver_unregister(&sgiwd93_driver);
}

module_init(sgiwd93_module_init);
module_exit(sgiwd93_module_exit);

MODULE_DESCRIPTION("SGI WD33C93 driver");
MODULE_AUTHOR("Ralf Baechle <ralf@linux-mips.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:sgiwd93");