// SPDX-License-Identifier: GPL-2.0-only
/* vmu-flash.c
 * Driver for SEGA Dreamcast Visual Memory Unit
 *
 * Copyright (c) Adrian McMenamin 2002 - 2009
 * Copyright (c) Paul Mundt 2001
 */
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/maple.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>

struct vmu_cache {
        unsigned char *buffer;          /* Cache */
        unsigned int block;             /* Which block was cached */
        unsigned long jiffies_atc;      /* When was it cached? */
        int valid;
};

struct mdev_part {
        struct maple_device *mdev;
        int partition;
};

struct vmupart {
        u16 user_blocks;
        u16 root_block;
        u16 numblocks;
        char *name;
        struct vmu_cache *pcache;
};

struct memcard {
        u16 tempA;
        u16 tempB;
        u32 partitions;
        u32 blocklen;
        u32 writecnt;
        u32 readcnt;
        u32 removable;
        int partition;
        int read;
        unsigned char *blockread;
        struct vmupart *parts;
        struct mtd_info *mtd;
};

struct vmu_block {
        unsigned int num; /* block number */
        unsigned int ofs; /* block offset */
};

static struct vmu_block *ofs_to_block(unsigned long src_ofs,
        struct mtd_info *mtd, int partition)
{
        struct vmu_block *vblock;
        struct maple_device *mdev;
        struct memcard *card;
        struct mdev_part *mpart;
        int num;

        mpart = mtd->priv;
        mdev = mpart->mdev;
        card = maple_get_drvdata(mdev);

        if (src_ofs >= card->parts[partition].numblocks * card->blocklen)
                goto failed;

        num = src_ofs / card->blocklen;
        if (num > card->parts[partition].numblocks)
                goto failed;

        vblock = kmalloc_obj(struct vmu_block);
        if (!vblock)
                goto failed;

        vblock->num = num;
        vblock->ofs = src_ofs % card->blocklen;
        return vblock;

failed:
        return NULL;
}

/* Maple bus callback function for reads */
static void vmu_blockread(struct mapleq *mq)
{
        struct maple_device *mdev;
        struct memcard *card;

        mdev = mq->dev;
        card = maple_get_drvdata(mdev);
        /* copy the read in data */

        if (unlikely(!card->blockread))
                return;

        memcpy(card->blockread, mq->recvbuf->buf + 12,
                card->blocklen/card->readcnt);

}

/* Interface with maple bus to read blocks
 * caching the results so that other parts
 * of the driver can access block reads */
static int maple_vmu_read_block(unsigned int num, unsigned char *buf,
        struct mtd_info *mtd)
{
        struct memcard *card;
        struct mdev_part *mpart;
        struct maple_device *mdev;
        int partition, error = 0, x, wait;
        unsigned char *blockread = NULL;
        struct vmu_cache *pcache;
        __be32 sendbuf;

        mpart = mtd->priv;
        mdev = mpart->mdev;
        partition = mpart->partition;
        card = maple_get_drvdata(mdev);
        pcache = card->parts[partition].pcache;
        pcache->valid = 0;

        /* prepare the cache for this block */
        if (!pcache->buffer) {
                pcache->buffer = kmalloc(card->blocklen, GFP_KERNEL);
                if (!pcache->buffer) {
                        dev_err(&mdev->dev, "VMU at (%d, %d) - read fails due"
                                " to lack of memory\n", mdev->port,
                                mdev->unit);
                        error = -ENOMEM;
                        goto outB;
                }
        }

        /*
        * Reads may be phased - again the hardware spec
        * supports this - though may not be any devices in
        * the wild that implement it, but we will here
        */
        for (x = 0; x < card->readcnt; x++) {
                sendbuf = cpu_to_be32(partition << 24 | x << 16 | num);

                if (atomic_read(&mdev->busy) == 1) {
                        wait_event_interruptible_timeout(mdev->maple_wait,
                                atomic_read(&mdev->busy) == 0, HZ);
                        if (atomic_read(&mdev->busy) == 1) {
                                dev_notice(&mdev->dev, "VMU at (%d, %d)"
                                        " is busy\n", mdev->port, mdev->unit);
                                error = -EAGAIN;
                                goto outB;
                        }
                }

                atomic_set(&mdev->busy, 1);
                blockread = kmalloc(card->blocklen/card->readcnt, GFP_KERNEL);
                if (!blockread) {
                        error = -ENOMEM;
                        atomic_set(&mdev->busy, 0);
                        goto outB;
                }
                card->blockread = blockread;

                maple_getcond_callback(mdev, vmu_blockread, 0,
                        MAPLE_FUNC_MEMCARD);
                error = maple_add_packet(mdev, MAPLE_FUNC_MEMCARD,
                                MAPLE_COMMAND_BREAD, 2, &sendbuf);
                /* Very long timeouts seem to be needed when box is stressed */
                wait = wait_event_interruptible_timeout(mdev->maple_wait,
                        (atomic_read(&mdev->busy) == 0 ||
                        atomic_read(&mdev->busy) == 2), HZ * 3);
                /*
                * MTD layer does not handle hotplugging well
                * so have to return errors when VMU is unplugged
                * in the middle of a read (busy == 2)
                */
                if (error || atomic_read(&mdev->busy) == 2) {
                        if (atomic_read(&mdev->busy) == 2)
                                error = -ENXIO;
                        atomic_set(&mdev->busy, 0);
                        card->blockread = NULL;
                        goto outA;
                }
                if (wait == 0 || wait == -ERESTARTSYS) {
                        card->blockread = NULL;
                        atomic_set(&mdev->busy, 0);
                        error = -EIO;
                        list_del_init(&(mdev->mq->list));
                        kfree(mdev->mq->sendbuf);
                        mdev->mq->sendbuf = NULL;
                        if (wait == -ERESTARTSYS) {
                                dev_warn(&mdev->dev, "VMU read on (%d, %d)"
                                        " interrupted on block 0x%X\n",
                                        mdev->port, mdev->unit, num);
                        } else
                                dev_notice(&mdev->dev, "VMU read on (%d, %d)"
                                        " timed out on block 0x%X\n",
                                        mdev->port, mdev->unit, num);
                        goto outA;
                }

                memcpy(buf + (card->blocklen/card->readcnt) * x, blockread,
                        card->blocklen/card->readcnt);

                memcpy(pcache->buffer + (card->blocklen/card->readcnt) * x,
                        card->blockread, card->blocklen/card->readcnt);
                card->blockread = NULL;
                pcache->block = num;
                pcache->jiffies_atc = jiffies;
                pcache->valid = 1;
                kfree(blockread);
        }

        return error;

outA:
        kfree(blockread);
outB:
        return error;
}

/* communicate with maple bus for phased writing */
static int maple_vmu_write_block(unsigned int num, const unsigned char *buf,
        struct mtd_info *mtd)
{
        struct memcard *card;
        struct mdev_part *mpart;
        struct maple_device *mdev;
        int partition, error, locking, x, phaselen, wait;
        __be32 *sendbuf;

        mpart = mtd->priv;
        mdev = mpart->mdev;
        partition = mpart->partition;
        card = maple_get_drvdata(mdev);

        phaselen = card->blocklen/card->writecnt;

        sendbuf = kmalloc(phaselen + 4, GFP_KERNEL);
        if (!sendbuf) {
                error = -ENOMEM;
                goto fail_nosendbuf;
        }
        for (x = 0; x < card->writecnt; x++) {
                sendbuf[0] = cpu_to_be32(partition << 24 | x << 16 | num);
                memcpy(&sendbuf[1], buf + phaselen * x, phaselen);
                /* wait until the device is not busy doing something else
                * or 1 second - which ever is longer */
                if (atomic_read(&mdev->busy) == 1) {
                        wait_event_interruptible_timeout(mdev->maple_wait,
                                atomic_read(&mdev->busy) == 0, HZ);
                        if (atomic_read(&mdev->busy) == 1) {
                                error = -EBUSY;
                                dev_notice(&mdev->dev, "VMU write at (%d, %d)"
                                        "failed - device is busy\n",
                                        mdev->port, mdev->unit);
                                goto fail_nolock;
                        }
                }
                atomic_set(&mdev->busy, 1);

                locking = maple_add_packet(mdev, MAPLE_FUNC_MEMCARD,
                        MAPLE_COMMAND_BWRITE, phaselen / 4 + 2, sendbuf);
                wait = wait_event_interruptible_timeout(mdev->maple_wait,
                        atomic_read(&mdev->busy) == 0, HZ/10);
                if (locking) {
                        error = -EIO;
                        atomic_set(&mdev->busy, 0);
                        goto fail_nolock;
                }
                if (atomic_read(&mdev->busy) == 2) {
                        atomic_set(&mdev->busy, 0);
                } else if (wait == 0 || wait == -ERESTARTSYS) {
                        error = -EIO;
                        dev_warn(&mdev->dev, "Write at (%d, %d) of block"
                                " 0x%X at phase %d failed: could not"
                                " communicate with VMU", mdev->port,
                                mdev->unit, num, x);
                        atomic_set(&mdev->busy, 0);
                        kfree(mdev->mq->sendbuf);
                        mdev->mq->sendbuf = NULL;
                        list_del_init(&(mdev->mq->list));
                        goto fail_nolock;
                }
        }
        kfree(sendbuf);

        return card->blocklen;

fail_nolock:
        kfree(sendbuf);
fail_nosendbuf:
        dev_err(&mdev->dev, "VMU (%d, %d): write failed\n", mdev->port,
                mdev->unit);
        return error;
}

/* mtd function to simulate reading byte by byte */
static unsigned char vmu_flash_read_char(unsigned long ofs, int *retval,
        struct mtd_info *mtd)
{
        struct vmu_block *vblock;
        struct memcard *card;
        struct mdev_part *mpart;
        struct maple_device *mdev;
        unsigned char *buf, ret;
        int partition, error;

        mpart = mtd->priv;
        mdev = mpart->mdev;
        partition = mpart->partition;
        card = maple_get_drvdata(mdev);
        *retval =  0;

        buf = kmalloc(card->blocklen, GFP_KERNEL);
        if (!buf) {
                *retval = 1;
                ret = -ENOMEM;
                goto finish;
        }

        vblock = ofs_to_block(ofs, mtd, partition);
        if (!vblock) {
                *retval = 3;
                ret = -ENOMEM;
                goto out_buf;
        }

        error = maple_vmu_read_block(vblock->num, buf, mtd);
        if (error) {
                ret = error;
                *retval = 2;
                goto out_vblock;
        }

        ret = buf[vblock->ofs];

out_vblock:
        kfree(vblock);
out_buf:
        kfree(buf);
finish:
        return ret;
}

/* mtd higher order function to read flash */
static int vmu_flash_read(struct mtd_info *mtd, loff_t from, size_t len,
        size_t *retlen,  u_char *buf)
{
        struct maple_device *mdev;
        struct memcard *card;
        struct mdev_part *mpart;
        struct vmu_cache *pcache;
        struct vmu_block *vblock;
        int index = 0, retval, partition, leftover, numblocks;
        unsigned char cx;

        mpart = mtd->priv;
        mdev = mpart->mdev;
        partition = mpart->partition;
        card = maple_get_drvdata(mdev);

        numblocks = card->parts[partition].numblocks;
        if (from + len > numblocks * card->blocklen)
                len = numblocks * card->blocklen - from;
        if (len == 0)
                return -EIO;
        /* Have we cached this bit already? */
        pcache = card->parts[partition].pcache;
        do {
                vblock =  ofs_to_block(from + index, mtd, partition);
                if (!vblock)
                        return -ENOMEM;
                /* Have we cached this and is the cache valid and timely? */
                if (pcache->valid &&
                        time_before(jiffies, pcache->jiffies_atc + HZ) &&
                        (pcache->block == vblock->num)) {
                        /* we have cached it, so do necessary copying */
                        leftover = card->blocklen - vblock->ofs;
                        if (vblock->ofs + len - index < card->blocklen) {
                                /* only a bit of this block to copy */
                                memcpy(buf + index,
                                        pcache->buffer + vblock->ofs,
                                        len - index);
                                index = len;
                        } else {
                                /* otherwise copy remainder of whole block */
                                memcpy(buf + index, pcache->buffer +
                                        vblock->ofs, leftover);
                                index += leftover;
                        }
                } else {
                        /*
                        * Not cached so read one byte -
                        * but cache the rest of the block
                        */
                        cx = vmu_flash_read_char(from + index, &retval, mtd);
                        if (retval) {
                                *retlen = index;
                                kfree(vblock);
                                return cx;
                        }
                        memset(buf + index, cx, 1);
                        index++;
                }
                kfree(vblock);
        } while (len > index);
        *retlen = index;

        return 0;
}

static int vmu_flash_write(struct mtd_info *mtd, loff_t to, size_t len,
        size_t *retlen, const u_char *buf)
{
        struct maple_device *mdev;
        struct memcard *card;
        struct mdev_part *mpart;
        int index = 0, partition, error = 0, numblocks;
        struct vmu_cache *pcache;
        struct vmu_block *vblock;
        unsigned char *buffer;

        mpart = mtd->priv;
        mdev = mpart->mdev;
        partition = mpart->partition;
        card = maple_get_drvdata(mdev);

        numblocks = card->parts[partition].numblocks;
        if (to + len > numblocks * card->blocklen)
                len = numblocks * card->blocklen - to;
        if (len == 0) {
                error = -EIO;
                goto failed;
        }

        vblock = ofs_to_block(to, mtd, partition);
        if (!vblock) {
                error = -ENOMEM;
                goto failed;
        }

        buffer = kmalloc(card->blocklen, GFP_KERNEL);
        if (!buffer) {
                error = -ENOMEM;
                goto fail_buffer;
        }

        do {
                /* Read in the block we are to write to */
                error = maple_vmu_read_block(vblock->num, buffer, mtd);
                if (error)
                        goto fail_io;

                do {
                        buffer[vblock->ofs] = buf[index];
                        vblock->ofs++;
                        index++;
                        if (index >= len)
                                break;
                } while (vblock->ofs < card->blocklen);

                /* write out new buffer */
                error = maple_vmu_write_block(vblock->num, buffer, mtd);
                /* invalidate the cache */
                pcache = card->parts[partition].pcache;
                pcache->valid = 0;

                if (error != card->blocklen)
                        goto fail_io;

                vblock->num++;
                vblock->ofs = 0;
        } while (len > index);

        kfree(buffer);
        *retlen = index;
        kfree(vblock);
        return 0;

fail_io:
        kfree(buffer);
fail_buffer:
        kfree(vblock);
failed:
        dev_err(&mdev->dev, "VMU write failing with error %d\n", error);
        return error;
}

static void vmu_flash_sync(struct mtd_info *mtd)
{
        /* Do nothing here */
}

/* Maple bus callback function to recursively query hardware details */
static void vmu_queryblocks(struct mapleq *mq)
{
        struct maple_device *mdev;
        unsigned short *res;
        struct memcard *card;
        __be32 partnum;
        struct vmu_cache *pcache;
        struct mdev_part *mpart;
        struct mtd_info *mtd_cur;
        struct vmupart *part_cur;
        int error;

        mdev = mq->dev;
        card = maple_get_drvdata(mdev);
        res = (unsigned short *) (mq->recvbuf->buf);
        card->tempA = res[12];
        card->tempB = res[6];

        dev_info(&mdev->dev, "VMU device at partition %d has %d user "
                "blocks with a root block at %d\n", card->partition,
                card->tempA, card->tempB);

        part_cur = &card->parts[card->partition];
        part_cur->user_blocks = card->tempA;
        part_cur->root_block = card->tempB;
        part_cur->numblocks = card->tempB + 1;
        part_cur->name = kmalloc(12, GFP_KERNEL);
        if (!part_cur->name)
                goto fail_name;

        sprintf(part_cur->name, "vmu%d.%d.%d",
                mdev->port, mdev->unit, card->partition);
        mtd_cur = &card->mtd[card->partition];
        mtd_cur->name = part_cur->name;
        mtd_cur->type = 8;
        mtd_cur->flags = MTD_WRITEABLE|MTD_NO_ERASE;
        mtd_cur->size = part_cur->numblocks * card->blocklen;
        mtd_cur->erasesize = card->blocklen;
        mtd_cur->_write = vmu_flash_write;
        mtd_cur->_read = vmu_flash_read;
        mtd_cur->_sync = vmu_flash_sync;
        mtd_cur->writesize = card->blocklen;

        mpart = kmalloc_obj(struct mdev_part);
        if (!mpart)
                goto fail_mpart;

        mpart->mdev = mdev;
        mpart->partition = card->partition;
        mtd_cur->priv = mpart;
        mtd_cur->owner = THIS_MODULE;

        pcache = kzalloc_obj(struct vmu_cache);
        if (!pcache)
                goto fail_cache_create;
        part_cur->pcache = pcache;

        error = mtd_device_register(mtd_cur, NULL, 0);
        if (error)
                goto fail_mtd_register;

        maple_getcond_callback(mdev, NULL, 0,
                MAPLE_FUNC_MEMCARD);

        /*
        * Set up a recursive call to the (probably theoretical)
        * second or more partition
        */
        if (++card->partition < card->partitions) {
                partnum = cpu_to_be32(card->partition << 24);
                maple_getcond_callback(mdev, vmu_queryblocks, 0,
                        MAPLE_FUNC_MEMCARD);
                maple_add_packet(mdev, MAPLE_FUNC_MEMCARD,
                        MAPLE_COMMAND_GETMINFO, 2, &partnum);
        }
        return;

fail_mtd_register:
        dev_err(&mdev->dev, "Could not register maple device at (%d, %d)"
                "error is 0x%X\n", mdev->port, mdev->unit, error);
        for (error = 0; error <= card->partition; error++) {
                kfree(((card->parts)[error]).pcache);
                ((card->parts)[error]).pcache = NULL;
        }
fail_cache_create:
fail_mpart:
        for (error = 0; error <= card->partition; error++) {
                kfree(((card->mtd)[error]).priv);
                ((card->mtd)[error]).priv = NULL;
        }
        maple_getcond_callback(mdev, NULL, 0,
                MAPLE_FUNC_MEMCARD);
        kfree(part_cur->name);
fail_name:
        return;
}

/* Handles very basic info about the flash, queries for details */
static int vmu_connect(struct maple_device *mdev)
{
        unsigned long test_flash_data, basic_flash_data;
        int c, error;
        struct memcard *card;
        u32 partnum = 0;

        test_flash_data = be32_to_cpu(mdev->devinfo.function);
        /* Need to count how many bits are set - to find out which
         * function_data element has details of the memory card
         */
        c = hweight_long(test_flash_data);

        basic_flash_data = be32_to_cpu(mdev->devinfo.function_data[c - 1]);

        card = kmalloc_obj(struct memcard);
        if (!card) {
                error = -ENOMEM;
                goto fail_nomem;
        }

        card->partitions = (basic_flash_data >> 24 & 0xFF) + 1;
        card->blocklen = ((basic_flash_data >> 16 & 0xFF) + 1) << 5;
        card->writecnt = basic_flash_data >> 12 & 0xF;
        card->readcnt = basic_flash_data >> 8 & 0xF;
        card->removable = basic_flash_data >> 7 & 1;

        card->partition = 0;

        /*
        * Not sure there are actually any multi-partition devices in the
        * real world, but the hardware supports them, so, so will we
        */
        card->parts = kmalloc_objs(struct vmupart, card->partitions);
        if (!card->parts) {
                error = -ENOMEM;
                goto fail_partitions;
        }

        card->mtd = kmalloc_objs(struct mtd_info, card->partitions);
        if (!card->mtd) {
                error = -ENOMEM;
                goto fail_mtd_info;
        }

        maple_set_drvdata(mdev, card);

        /*
        * We want to trap meminfo not get cond
        * so set interval to zero, but rely on maple bus
        * driver to pass back the results of the meminfo
        */
        maple_getcond_callback(mdev, vmu_queryblocks, 0,
                MAPLE_FUNC_MEMCARD);

        /* Make sure we are clear to go */
        if (atomic_read(&mdev->busy) == 1) {
                wait_event_interruptible_timeout(mdev->maple_wait,
                        atomic_read(&mdev->busy) == 0, HZ);
                if (atomic_read(&mdev->busy) == 1) {
                        dev_notice(&mdev->dev, "VMU at (%d, %d) is busy\n",
                                mdev->port, mdev->unit);
                        error = -EAGAIN;
                        goto fail_device_busy;
                }
        }

        atomic_set(&mdev->busy, 1);

        /*
        * Set up the minfo call: vmu_queryblocks will handle
        * the information passed back
        */
        error = maple_add_packet(mdev, MAPLE_FUNC_MEMCARD,
                MAPLE_COMMAND_GETMINFO, 2, &partnum);
        if (error) {
                dev_err(&mdev->dev, "Could not lock VMU at (%d, %d)"
                        " error is 0x%X\n", mdev->port, mdev->unit, error);
                goto fail_mtd_info;
        }
        return 0;

fail_device_busy:
        kfree(card->mtd);
fail_mtd_info:
        kfree(card->parts);
fail_partitions:
        kfree(card);
fail_nomem:
        return error;
}

static void vmu_disconnect(struct maple_device *mdev)
{
        struct memcard *card;
        struct mdev_part *mpart;
        int x;

        mdev->callback = NULL;
        card = maple_get_drvdata(mdev);
        for (x = 0; x < card->partitions; x++) {
                mpart = ((card->mtd)[x]).priv;
                mpart->mdev = NULL;
                mtd_device_unregister(&((card->mtd)[x]));
                kfree(((card->parts)[x]).name);
        }
        kfree(card->parts);
        kfree(card->mtd);
        kfree(card);
}

/* Callback to handle eccentricities of both mtd subsystem
 * and general flakyness of Dreamcast VMUs
 */
static int vmu_can_unload(struct maple_device *mdev)
{
        struct memcard *card;
        int x;
        struct mtd_info *mtd;

        card = maple_get_drvdata(mdev);
        for (x = 0; x < card->partitions; x++) {
                mtd = &((card->mtd)[x]);
                if (kref_read(&mtd->refcnt))
                        return 0;
        }
        return 1;
}

#define ERRSTR "VMU at (%d, %d) file error -"

static void vmu_file_error(struct maple_device *mdev, void *recvbuf)
{
        enum maple_file_errors error = ((int *)recvbuf)[1];

        switch (error) {

        case MAPLE_FILEERR_INVALID_PARTITION:
                dev_notice(&mdev->dev, ERRSTR " invalid partition number\n",
                        mdev->port, mdev->unit);
                break;

        case MAPLE_FILEERR_PHASE_ERROR:
                dev_notice(&mdev->dev, ERRSTR " phase error\n",
                        mdev->port, mdev->unit);
                break;

        case MAPLE_FILEERR_INVALID_BLOCK:
                dev_notice(&mdev->dev, ERRSTR " invalid block number\n",
                        mdev->port, mdev->unit);
                break;

        case MAPLE_FILEERR_WRITE_ERROR:
                dev_notice(&mdev->dev, ERRSTR " write error\n",
                        mdev->port, mdev->unit);
                break;

        case MAPLE_FILEERR_INVALID_WRITE_LENGTH:
                dev_notice(&mdev->dev, ERRSTR " invalid write length\n",
                        mdev->port, mdev->unit);
                break;

        case MAPLE_FILEERR_BAD_CRC:
                dev_notice(&mdev->dev, ERRSTR " bad CRC\n",
                        mdev->port, mdev->unit);
                break;

        default:
                dev_notice(&mdev->dev, ERRSTR " 0x%X\n",
                        mdev->port, mdev->unit, error);
        }
}


static int probe_maple_vmu(struct device *dev)
{
        struct maple_device *mdev = to_maple_dev(dev);
        struct maple_driver *mdrv = to_maple_driver(dev->driver);

        mdev->can_unload = vmu_can_unload;
        mdev->fileerr_handler = vmu_file_error;
        mdev->driver = mdrv;

        return vmu_connect(mdev);
}

static int remove_maple_vmu(struct device *dev)
{
        struct maple_device *mdev = to_maple_dev(dev);

        vmu_disconnect(mdev);
        return 0;
}

static struct maple_driver vmu_flash_driver = {
        .function =     MAPLE_FUNC_MEMCARD,
        .drv = {
                .name =         "Dreamcast_visual_memory",
                .probe =        probe_maple_vmu,
                .remove =       remove_maple_vmu,
        },
};

static int __init vmu_flash_map_init(void)
{
        return maple_driver_register(&vmu_flash_driver);
}

static void __exit vmu_flash_map_exit(void)
{
        maple_driver_unregister(&vmu_flash_driver);
}

module_init(vmu_flash_map_init);
module_exit(vmu_flash_map_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Adrian McMenamin");
MODULE_DESCRIPTION("Flash mapping for Sega Dreamcast visual memory");