/*
 * Linux driver for Disk-On-Chip Millennium
 * (c) 1999 Machine Vision Holdings, Inc.
 * (c) 1999, 2000 David Woodhouse <dwmw2@infradead.org>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/bitops.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/doc2000.h>

/* #define ECC_DEBUG */

/* I have no idea why some DoC chips can not use memcop_form|to_io().
 * This may be due to the different revisions of the ASIC controller built-in or
 * simplily a QA/Bug issue. Who knows ?? If you have trouble, please uncomment
 * this:*/
#undef USE_MEMCPY

static int doc_read(struct mtd_info *mtd, loff_t from, size_t len,
                    size_t *retlen, u_char *buf);
static int doc_write(struct mtd_info *mtd, loff_t to, size_t len,
                     size_t *retlen, const u_char *buf);
static int doc_read_oob(struct mtd_info *mtd, loff_t ofs,
                        struct mtd_oob_ops *ops);
static int doc_write_oob(struct mtd_info *mtd, loff_t ofs,
                         struct mtd_oob_ops *ops);
static int doc_erase (struct mtd_info *mtd, struct erase_info *instr);

static struct mtd_info *docmillist = NULL;

/* Perform the required delay cycles by reading from the NOP register */
static void DoC_Delay(void __iomem * docptr, unsigned short cycles)
{
        volatile char dummy;
        int i;

        for (i = 0; i < cycles; i++)
                dummy = ReadDOC(docptr, NOP);
}

/* DOC_WaitReady: Wait for RDY line to be asserted by the flash chip */
static int _DoC_WaitReady(void __iomem * docptr)
{
        unsigned short c = 0xffff;

        DEBUG(MTD_DEBUG_LEVEL3,
              "_DoC_WaitReady called for out-of-line wait\n");

        /* Out-of-line routine to wait for chip response */
        while (!(ReadDOC(docptr, CDSNControl) & CDSN_CTRL_FR_B) && --c)
                ;

        if (c == 0)
                DEBUG(MTD_DEBUG_LEVEL2, "_DoC_WaitReady timed out.\n");

        return (c == 0);
}

static inline int DoC_WaitReady(void __iomem * docptr)
{
        /* This is inline, to optimise the common case, where it's ready instantly */
        int ret = 0;

        /* 4 read form NOP register should be issued in prior to the read from CDSNControl
           see Software Requirement 11.4 item 2. */
        DoC_Delay(docptr, 4);

        if (!(ReadDOC(docptr, CDSNControl) & CDSN_CTRL_FR_B))
                /* Call the out-of-line routine to wait */
                ret = _DoC_WaitReady(docptr);

        /* issue 2 read from NOP register after reading from CDSNControl register
           see Software Requirement 11.4 item 2. */
        DoC_Delay(docptr, 2);

        return ret;
}

/* DoC_Command: Send a flash command to the flash chip through the CDSN IO register
   with the internal pipeline. Each of 4 delay cycles (read from the NOP register) is
   required after writing to CDSN Control register, see Software Requirement 11.4 item 3. */

static void DoC_Command(void __iomem * docptr, unsigned char command,
                               unsigned char xtraflags)
{
        /* Assert the CLE (Command Latch Enable) line to the flash chip */
        WriteDOC(xtraflags | CDSN_CTRL_CLE | CDSN_CTRL_CE, docptr, CDSNControl);
        DoC_Delay(docptr, 4);

        /* Send the command */
        WriteDOC(command, docptr, Mil_CDSN_IO);
        WriteDOC(0x00, docptr, WritePipeTerm);

        /* Lower the CLE line */
        WriteDOC(xtraflags | CDSN_CTRL_CE, docptr, CDSNControl);
        DoC_Delay(docptr, 4);
}

/* DoC_Address: Set the current address for the flash chip through the CDSN IO register
   with the internal pipeline. Each of 4 delay cycles (read from the NOP register) is
   required after writing to CDSN Control register, see Software Requirement 11.4 item 3. */

static inline void DoC_Address(void __iomem * docptr, int numbytes, unsigned long ofs,
                               unsigned char xtraflags1, unsigned char xtraflags2)
{
        /* Assert the ALE (Address Latch Enable) line to the flash chip */
        WriteDOC(xtraflags1 | CDSN_CTRL_ALE | CDSN_CTRL_CE, docptr, CDSNControl);
        DoC_Delay(docptr, 4);

        /* Send the address */
        switch (numbytes)
            {
            case 1:
                    /* Send single byte, bits 0-7. */
                    WriteDOC(ofs & 0xff, docptr, Mil_CDSN_IO);
                    WriteDOC(0x00, docptr, WritePipeTerm);
                    break;
            case 2:
                    /* Send bits 9-16 followed by 17-23 */
                    WriteDOC((ofs >> 9)  & 0xff, docptr, Mil_CDSN_IO);
                    WriteDOC((ofs >> 17) & 0xff, docptr, Mil_CDSN_IO);
                    WriteDOC(0x00, docptr, WritePipeTerm);
                break;
            case 3:
                    /* Send 0-7, 9-16, then 17-23 */
                    WriteDOC(ofs & 0xff, docptr, Mil_CDSN_IO);
                    WriteDOC((ofs >> 9)  & 0xff, docptr, Mil_CDSN_IO);
                    WriteDOC((ofs >> 17) & 0xff, docptr, Mil_CDSN_IO);
                    WriteDOC(0x00, docptr, WritePipeTerm);
                break;
            default:
                return;
            }

        /* Lower the ALE line */
        WriteDOC(xtraflags1 | xtraflags2 | CDSN_CTRL_CE, docptr, CDSNControl);
        DoC_Delay(docptr, 4);
}

/* DoC_SelectChip: Select a given flash chip within the current floor */
static int DoC_SelectChip(void __iomem * docptr, int chip)
{
        /* Select the individual flash chip requested */
        WriteDOC(chip, docptr, CDSNDeviceSelect);
        DoC_Delay(docptr, 4);

        /* Wait for it to be ready */
        return DoC_WaitReady(docptr);
}

/* DoC_SelectFloor: Select a given floor (bank of flash chips) */
static int DoC_SelectFloor(void __iomem * docptr, int floor)
{
        /* Select the floor (bank) of chips required */
        WriteDOC(floor, docptr, FloorSelect);

        /* Wait for the chip to be ready */
        return DoC_WaitReady(docptr);
}

/* DoC_IdentChip: Identify a given NAND chip given {floor,chip} */
static int DoC_IdentChip(struct DiskOnChip *doc, int floor, int chip)
{
        int mfr, id, i, j;
        volatile char dummy;

        /* Page in the required floor/chip
           FIXME: is this supported by Millennium ?? */
        DoC_SelectFloor(doc->virtadr, floor);
        DoC_SelectChip(doc->virtadr, chip);

        /* Reset the chip, see Software Requirement 11.4 item 1. */
        DoC_Command(doc->virtadr, NAND_CMD_RESET, CDSN_CTRL_WP);
        DoC_WaitReady(doc->virtadr);

        /* Read the NAND chip ID: 1. Send ReadID command */
        DoC_Command(doc->virtadr, NAND_CMD_READID, CDSN_CTRL_WP);

        /* Read the NAND chip ID: 2. Send address byte zero */
        DoC_Address(doc->virtadr, 1, 0x00, CDSN_CTRL_WP, 0x00);

        /* Read the manufacturer and device id codes of the flash device through
           CDSN IO register see Software Requirement 11.4 item 5.*/
        dummy = ReadDOC(doc->virtadr, ReadPipeInit);
        DoC_Delay(doc->virtadr, 2);
        mfr = ReadDOC(doc->virtadr, Mil_CDSN_IO);

        DoC_Delay(doc->virtadr, 2);
        id  = ReadDOC(doc->virtadr, Mil_CDSN_IO);
        dummy = ReadDOC(doc->virtadr, LastDataRead);

        /* No response - return failure */
        if (mfr == 0xff || mfr == 0)
                return 0;

        /* FIXME: to deal with multi-flash on multi-Millennium case more carefully */
        for (i = 0; nand_flash_ids[i].name != NULL; i++) {
                if ( id == nand_flash_ids[i].id) {
                        /* Try to identify manufacturer */
                        for (j = 0; nand_manuf_ids[j].id != 0x0; j++) {
                                if (nand_manuf_ids[j].id == mfr)
                                        break;
                        }
                        printk(KERN_INFO "Flash chip found: Manufacturer ID: %2.2X, "
                               "Chip ID: %2.2X (%s:%s)\n",
                               mfr, id, nand_manuf_ids[j].name, nand_flash_ids[i].name);
                        doc->mfr = mfr;
                        doc->id = id;
                        doc->chipshift = ffs((nand_flash_ids[i].chipsize << 20)) - 1;
                        break;
                }
        }

        if (nand_flash_ids[i].name == NULL)
                return 0;
        else
                return 1;
}

/* DoC_ScanChips: Find all NAND chips present in a DiskOnChip, and identify them */
static void DoC_ScanChips(struct DiskOnChip *this)
{
        int floor, chip;
        int numchips[MAX_FLOORS_MIL];
        int ret;

        this->numchips = 0;
        this->mfr = 0;
        this->id = 0;

        /* For each floor, find the number of valid chips it contains */
        for (floor = 0,ret = 1; floor < MAX_FLOORS_MIL; floor++) {
                numchips[floor] = 0;
                for (chip = 0; chip < MAX_CHIPS_MIL && ret != 0; chip++) {
                        ret = DoC_IdentChip(this, floor, chip);
                        if (ret) {
                                numchips[floor]++;
                                this->numchips++;
                        }
                }
        }
        /* If there are none at all that we recognise, bail */
        if (!this->numchips) {
                printk("No flash chips recognised.\n");
                return;
        }

        /* Allocate an array to hold the information for each chip */
        this->chips = kmalloc(sizeof(struct Nand) * this->numchips, GFP_KERNEL);
        if (!this->chips){
                printk("No memory for allocating chip info structures\n");
                return;
        }

        /* Fill out the chip array with {floor, chipno} for each
         * detected chip in the device. */
        for (floor = 0, ret = 0; floor < MAX_FLOORS_MIL; floor++) {
                for (chip = 0 ; chip < numchips[floor] ; chip++) {
                        this->chips[ret].floor = floor;
                        this->chips[ret].chip = chip;
                        this->chips[ret].curadr = 0;
                        this->chips[ret].curmode = 0x50;
                        ret++;
                }
        }

        /* Calculate and print the total size of the device */
        this->totlen = this->numchips * (1 << this->chipshift);
        printk(KERN_INFO "%d flash chips found. Total DiskOnChip size: %ld MiB\n",
               this->numchips ,this->totlen >> 20);
}

static int DoCMil_is_alias(struct DiskOnChip *doc1, struct DiskOnChip *doc2)
{
        int tmp1, tmp2, retval;

        if (doc1->physadr == doc2->physadr)
                return 1;

        /* Use the alias resolution register which was set aside for this
         * purpose. If it's value is the same on both chips, they might
         * be the same chip, and we write to one and check for a change in
         * the other. It's unclear if this register is usuable in the
         * DoC 2000 (it's in the Millenium docs), but it seems to work. */
        tmp1 = ReadDOC(doc1->virtadr, AliasResolution);
        tmp2 = ReadDOC(doc2->virtadr, AliasResolution);
        if (tmp1 != tmp2)
                return 0;

        WriteDOC((tmp1+1) % 0xff, doc1->virtadr, AliasResolution);
        tmp2 = ReadDOC(doc2->virtadr, AliasResolution);
        if (tmp2 == (tmp1+1) % 0xff)
                retval = 1;
        else
                retval = 0;

        /* Restore register contents.  May not be necessary, but do it just to
         * be safe. */
        WriteDOC(tmp1, doc1->virtadr, AliasResolution);

        return retval;
}

/* This routine is found from the docprobe code by symbol_get(),
 * which will bump the use count of this module. */
void DoCMil_init(struct mtd_info *mtd)
{
        struct DiskOnChip *this = mtd->priv;
        struct DiskOnChip *old = NULL;

        /* We must avoid being called twice for the same device. */
        if (docmillist)
                old = docmillist->priv;

        while (old) {
                if (DoCMil_is_alias(this, old)) {
                        printk(KERN_NOTICE "Ignoring DiskOnChip Millennium at "
                               "0x%lX - already configured\n", this->physadr);
                        iounmap(this->virtadr);
                        kfree(mtd);
                        return;
                }
                if (old->nextdoc)
                        old = old->nextdoc->priv;
                else
                        old = NULL;
        }

        mtd->name = "DiskOnChip Millennium";
        printk(KERN_NOTICE "DiskOnChip Millennium found at address 0x%lX\n",
               this->physadr);

        mtd->type = MTD_NANDFLASH;
        mtd->flags = MTD_CAP_NANDFLASH;
        mtd->size = 0;

        /* FIXME: erase size is not always 8KiB */
        mtd->erasesize = 0x2000;

        mtd->writesize = 512;
        mtd->oobsize = 16;
        mtd->owner = THIS_MODULE;
        mtd->erase = doc_erase;
        mtd->point = NULL;
        mtd->unpoint = NULL;
        mtd->read = doc_read;
        mtd->write = doc_write;
        mtd->read_oob = doc_read_oob;
        mtd->write_oob = doc_write_oob;
        mtd->sync = NULL;

        this->totlen = 0;
        this->numchips = 0;
        this->curfloor = -1;
        this->curchip = -1;

        /* Ident all the chips present. */
        DoC_ScanChips(this);

        if (!this->totlen) {
                kfree(mtd);
                iounmap(this->virtadr);
        } else {
                this->nextdoc = docmillist;
                docmillist = mtd;
                mtd->size  = this->totlen;
                add_mtd_device(mtd);
                return;
        }
}
EXPORT_SYMBOL_GPL(DoCMil_init);

static int doc_read (struct mtd_info *mtd, loff_t from, size_t len,
                     size_t *retlen, u_char *buf)
{
        int i, ret;
        volatile char dummy;
        unsigned char syndrome[6], eccbuf[6];
        struct DiskOnChip *this = mtd->priv;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip = &this->chips[from >> (this->chipshift)];

        /* Don't allow read past end of device */
        if (from >= this->totlen)
                return -EINVAL;

        /* Don't allow a single read to cross a 512-byte block boundary */
        if (from + len > ((from | 0x1ff) + 1))
                len = ((from | 0x1ff) + 1) - from;

        /* Find the chip which is to be used and select it */
        if (this->curfloor != mychip->floor) {
                DoC_SelectFloor(docptr, mychip->floor);
                DoC_SelectChip(docptr, mychip->chip);
        } else if (this->curchip != mychip->chip) {
                DoC_SelectChip(docptr, mychip->chip);
        }
        this->curfloor = mychip->floor;
        this->curchip = mychip->chip;

        /* issue the Read0 or Read1 command depend on which half of the page
           we are accessing. Polling the Flash Ready bit after issue 3 bytes
           address in Sequence Read Mode, see Software Requirement 11.4 item 1.*/
        DoC_Command(docptr, (from >> 8) & 1, CDSN_CTRL_WP);
        DoC_Address(docptr, 3, from, CDSN_CTRL_WP, 0x00);
        DoC_WaitReady(docptr);

        /* init the ECC engine, see Reed-Solomon EDC/ECC 11.1 .*/
        WriteDOC (DOC_ECC_RESET, docptr, ECCConf);
        WriteDOC (DOC_ECC_EN, docptr, ECCConf);

        /* Read the data via the internal pipeline through CDSN IO register,
           see Pipelined Read Operations 11.3 */
        dummy = ReadDOC(docptr, ReadPipeInit);
#ifndef USE_MEMCPY
        for (i = 0; i < len-1; i++) {
                /* N.B. you have to increase the source address in this way or the
                   ECC logic will not work properly */
                buf[i] = ReadDOC(docptr, Mil_CDSN_IO + (i & 0xff));
        }
#else
        memcpy_fromio(buf, docptr + DoC_Mil_CDSN_IO, len - 1);
#endif
        buf[len - 1] = ReadDOC(docptr, LastDataRead);

        /* Let the caller know we completed it */
        *retlen = len;
        ret = 0;

        /* Read the ECC data from Spare Data Area,
           see Reed-Solomon EDC/ECC 11.1 */
        dummy = ReadDOC(docptr, ReadPipeInit);
#ifndef USE_MEMCPY
        for (i = 0; i < 5; i++) {
                /* N.B. you have to increase the source address in this way or the
                   ECC logic will not work properly */
                eccbuf[i] = ReadDOC(docptr, Mil_CDSN_IO + i);
        }
#else
        memcpy_fromio(eccbuf, docptr + DoC_Mil_CDSN_IO, 5);
#endif
        eccbuf[5] = ReadDOC(docptr, LastDataRead);

        /* Flush the pipeline */
        dummy = ReadDOC(docptr, ECCConf);
        dummy = ReadDOC(docptr, ECCConf);

        /* Check the ECC Status */
        if (ReadDOC(docptr, ECCConf) & 0x80) {
                int nb_errors;
                /* There was an ECC error */
#ifdef ECC_DEBUG
                printk("DiskOnChip ECC Error: Read at %lx\n", (long)from);
#endif
                /* Read the ECC syndrom through the DiskOnChip ECC logic.
                   These syndrome will be all ZERO when there is no error */
                for (i = 0; i < 6; i++) {
                        syndrome[i] = ReadDOC(docptr, ECCSyndrome0 + i);
                }
                nb_errors = doc_decode_ecc(buf, syndrome);
#ifdef ECC_DEBUG
                printk("ECC Errors corrected: %x\n", nb_errors);
#endif
                if (nb_errors < 0) {
                        /* We return error, but have actually done the read. Not that
                           this can be told to user-space, via sys_read(), but at least
                           MTD-aware stuff can know about it by checking *retlen */
                        ret = -EIO;
                }
        }

#ifdef PSYCHO_DEBUG
        printk("ECC DATA at %lx: %2.2X %2.2X %2.2X %2.2X %2.2X %2.2X\n",
               (long)from, eccbuf[0], eccbuf[1], eccbuf[2], eccbuf[3],
               eccbuf[4], eccbuf[5]);
#endif

        /* disable the ECC engine */
        WriteDOC(DOC_ECC_DIS, docptr , ECCConf);

        return ret;
}

static int doc_write (struct mtd_info *mtd, loff_t to, size_t len,
                      size_t *retlen, const u_char *buf)
{
        int i,ret = 0;
        char eccbuf[6];
        volatile char dummy;
        struct DiskOnChip *this = mtd->priv;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip = &this->chips[to >> (this->chipshift)];

        /* Don't allow write past end of device */
        if (to >= this->totlen)
                return -EINVAL;

#if 0
        /* Don't allow a single write to cross a 512-byte block boundary */
        if (to + len > ( (to | 0x1ff) + 1))
                len = ((to | 0x1ff) + 1) - to;
#else
        /* Don't allow writes which aren't exactly one block */
        if (to & 0x1ff || len != 0x200)
                return -EINVAL;
#endif

        /* Find the chip which is to be used and select it */
        if (this->curfloor != mychip->floor) {
                DoC_SelectFloor(docptr, mychip->floor);
                DoC_SelectChip(docptr, mychip->chip);
        } else if (this->curchip != mychip->chip) {
                DoC_SelectChip(docptr, mychip->chip);
        }
        this->curfloor = mychip->floor;
        this->curchip = mychip->chip;

        /* Reset the chip, see Software Requirement 11.4 item 1. */
        DoC_Command(docptr, NAND_CMD_RESET, 0x00);
        DoC_WaitReady(docptr);
        /* Set device to main plane of flash */
        DoC_Command(docptr, NAND_CMD_READ0, 0x00);

        /* issue the Serial Data In command to initial the Page Program process */
        DoC_Command(docptr, NAND_CMD_SEQIN, 0x00);
        DoC_Address(docptr, 3, to, 0x00, 0x00);
        DoC_WaitReady(docptr);

        /* init the ECC engine, see Reed-Solomon EDC/ECC 11.1 .*/
        WriteDOC (DOC_ECC_RESET, docptr, ECCConf);
        WriteDOC (DOC_ECC_EN | DOC_ECC_RW, docptr, ECCConf);

        /* Write the data via the internal pipeline through CDSN IO register,
           see Pipelined Write Operations 11.2 */
#ifndef USE_MEMCPY
        for (i = 0; i < len; i++) {
                /* N.B. you have to increase the source address in this way or the
                   ECC logic will not work properly */
                WriteDOC(buf[i], docptr, Mil_CDSN_IO + i);
        }
#else
        memcpy_toio(docptr + DoC_Mil_CDSN_IO, buf, len);
#endif
        WriteDOC(0x00, docptr, WritePipeTerm);

        /* Write ECC data to flash, the ECC info is generated by the DiskOnChip ECC logic
           see Reed-Solomon EDC/ECC 11.1 */
        WriteDOC(0, docptr, NOP);
        WriteDOC(0, docptr, NOP);
        WriteDOC(0, docptr, NOP);

        /* Read the ECC data through the DiskOnChip ECC logic */
        for (i = 0; i < 6; i++) {
                eccbuf[i] = ReadDOC(docptr, ECCSyndrome0 + i);
        }

        /* ignore the ECC engine */
        WriteDOC(DOC_ECC_DIS, docptr , ECCConf);

#ifndef USE_MEMCPY
        /* Write the ECC data to flash */
        for (i = 0; i < 6; i++) {
                /* N.B. you have to increase the source address in this way or the
                   ECC logic will not work properly */
                WriteDOC(eccbuf[i], docptr, Mil_CDSN_IO + i);
        }
#else
        memcpy_toio(docptr + DoC_Mil_CDSN_IO, eccbuf, 6);
#endif

        /* write the block status BLOCK_USED (0x5555) at the end of ECC data
           FIXME: this is only a hack for programming the IPL area for LinuxBIOS
           and should be replace with proper codes in user space utilities */
        WriteDOC(0x55, docptr, Mil_CDSN_IO);
        WriteDOC(0x55, docptr, Mil_CDSN_IO + 1);

        WriteDOC(0x00, docptr, WritePipeTerm);

#ifdef PSYCHO_DEBUG
        printk("OOB data at %lx is %2.2X %2.2X %2.2X %2.2X %2.2X %2.2X\n",
               (long) to, eccbuf[0], eccbuf[1], eccbuf[2], eccbuf[3],
               eccbuf[4], eccbuf[5]);
#endif

        /* Commit the Page Program command and wait for ready
           see Software Requirement 11.4 item 1.*/
        DoC_Command(docptr, NAND_CMD_PAGEPROG, 0x00);
        DoC_WaitReady(docptr);

        /* Read the status of the flash device through CDSN IO register
           see Software Requirement 11.4 item 5.*/
        DoC_Command(docptr, NAND_CMD_STATUS, CDSN_CTRL_WP);
        dummy = ReadDOC(docptr, ReadPipeInit);
        DoC_Delay(docptr, 2);
        if (ReadDOC(docptr, Mil_CDSN_IO) & 1) {
                printk("Error programming flash\n");
                /* Error in programming
                   FIXME: implement Bad Block Replacement (in nftl.c ??) */
                *retlen = 0;
                ret = -EIO;
        }
        dummy = ReadDOC(docptr, LastDataRead);

        /* Let the caller know we completed it */
        *retlen = len;

        return ret;
}

static int doc_read_oob(struct mtd_info *mtd, loff_t ofs,
                        struct mtd_oob_ops *ops)
{
#ifndef USE_MEMCPY
        int i;
#endif
        volatile char dummy;
        struct DiskOnChip *this = mtd->priv;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip = &this->chips[ofs >> this->chipshift];
        uint8_t *buf = ops->oobbuf;
        size_t len = ops->len;

        BUG_ON(ops->mode != MTD_OOB_PLACE);

        ofs += ops->ooboffs;

        /* Find the chip which is to be used and select it */
        if (this->curfloor != mychip->floor) {
                DoC_SelectFloor(docptr, mychip->floor);
                DoC_SelectChip(docptr, mychip->chip);
        } else if (this->curchip != mychip->chip) {
                DoC_SelectChip(docptr, mychip->chip);
        }
        this->curfloor = mychip->floor;
        this->curchip = mychip->chip;

        /* disable the ECC engine */
        WriteDOC (DOC_ECC_RESET, docptr, ECCConf);
        WriteDOC (DOC_ECC_DIS, docptr, ECCConf);

        /* issue the Read2 command to set the pointer to the Spare Data Area.
           Polling the Flash Ready bit after issue 3 bytes address in
           Sequence Read Mode, see Software Requirement 11.4 item 1.*/
        DoC_Command(docptr, NAND_CMD_READOOB, CDSN_CTRL_WP);
        DoC_Address(docptr, 3, ofs, CDSN_CTRL_WP, 0x00);
        DoC_WaitReady(docptr);

        /* Read the data out via the internal pipeline through CDSN IO register,
           see Pipelined Read Operations 11.3 */
        dummy = ReadDOC(docptr, ReadPipeInit);
#ifndef USE_MEMCPY
        for (i = 0; i < len-1; i++) {
                /* N.B. you have to increase the source address in this way or the
                   ECC logic will not work properly */
                buf[i] = ReadDOC(docptr, Mil_CDSN_IO + i);
        }
#else
        memcpy_fromio(buf, docptr + DoC_Mil_CDSN_IO, len - 1);
#endif
        buf[len - 1] = ReadDOC(docptr, LastDataRead);

        ops->retlen = len;

        return 0;
}

static int doc_write_oob(struct mtd_info *mtd, loff_t ofs,
                         struct mtd_oob_ops *ops)
{
#ifndef USE_MEMCPY
        int i;
#endif
        volatile char dummy;
        int ret = 0;
        struct DiskOnChip *this = mtd->priv;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip = &this->chips[ofs >> this->chipshift];
        uint8_t *buf = ops->oobbuf;
        size_t len = ops->len;

        BUG_ON(ops->mode != MTD_OOB_PLACE);

        ofs += ops->ooboffs;

        /* Find the chip which is to be used and select it */
        if (this->curfloor != mychip->floor) {
                DoC_SelectFloor(docptr, mychip->floor);
                DoC_SelectChip(docptr, mychip->chip);
        } else if (this->curchip != mychip->chip) {
                DoC_SelectChip(docptr, mychip->chip);
        }
        this->curfloor = mychip->floor;
        this->curchip = mychip->chip;

        /* disable the ECC engine */
        WriteDOC (DOC_ECC_RESET, docptr, ECCConf);
        WriteDOC (DOC_ECC_DIS, docptr, ECCConf);

        /* Reset the chip, see Software Requirement 11.4 item 1. */
        DoC_Command(docptr, NAND_CMD_RESET, CDSN_CTRL_WP);
        DoC_WaitReady(docptr);
        /* issue the Read2 command to set the pointer to the Spare Data Area. */
        DoC_Command(docptr, NAND_CMD_READOOB, CDSN_CTRL_WP);

        /* issue the Serial Data In command to initial the Page Program process */
        DoC_Command(docptr, NAND_CMD_SEQIN, 0x00);
        DoC_Address(docptr, 3, ofs, 0x00, 0x00);

        /* Write the data via the internal pipeline through CDSN IO register,
           see Pipelined Write Operations 11.2 */
#ifndef USE_MEMCPY
        for (i = 0; i < len; i++) {
                /* N.B. you have to increase the source address in this way or the
                   ECC logic will not work properly */
                WriteDOC(buf[i], docptr, Mil_CDSN_IO + i);
        }
#else
        memcpy_toio(docptr + DoC_Mil_CDSN_IO, buf, len);
#endif
        WriteDOC(0x00, docptr, WritePipeTerm);

        /* Commit the Page Program command and wait for ready
           see Software Requirement 11.4 item 1.*/
        DoC_Command(docptr, NAND_CMD_PAGEPROG, 0x00);
        DoC_WaitReady(docptr);

        /* Read the status of the flash device through CDSN IO register
           see Software Requirement 11.4 item 5.*/
        DoC_Command(docptr, NAND_CMD_STATUS, 0x00);
        dummy = ReadDOC(docptr, ReadPipeInit);
        DoC_Delay(docptr, 2);
        if (ReadDOC(docptr, Mil_CDSN_IO) & 1) {
                printk("Error programming oob data\n");
                /* FIXME: implement Bad Block Replacement (in nftl.c ??) */
                ops->retlen = 0;
                ret = -EIO;
        }
        dummy = ReadDOC(docptr, LastDataRead);

        ops->retlen = len;

        return ret;
}

int doc_erase (struct mtd_info *mtd, struct erase_info *instr)
{
        volatile char dummy;
        struct DiskOnChip *this = mtd->priv;
        __u32 ofs = instr->addr;
        __u32 len = instr->len;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip = &this->chips[ofs >> this->chipshift];

        if (len != mtd->erasesize)
                printk(KERN_WARNING "Erase not right size (%x != %x)n",
                       len, mtd->erasesize);

        /* Find the chip which is to be used and select it */
        if (this->curfloor != mychip->floor) {
                DoC_SelectFloor(docptr, mychip->floor);
                DoC_SelectChip(docptr, mychip->chip);
        } else if (this->curchip != mychip->chip) {
                DoC_SelectChip(docptr, mychip->chip);
        }
        this->curfloor = mychip->floor;
        this->curchip = mychip->chip;

        instr->state = MTD_ERASE_PENDING;

        /* issue the Erase Setup command */
        DoC_Command(docptr, NAND_CMD_ERASE1, 0x00);
        DoC_Address(docptr, 2, ofs, 0x00, 0x00);

        /* Commit the Erase Start command and wait for ready
           see Software Requirement 11.4 item 1.*/
        DoC_Command(docptr, NAND_CMD_ERASE2, 0x00);
        DoC_WaitReady(docptr);

        instr->state = MTD_ERASING;

        /* Read the status of the flash device through CDSN IO register
           see Software Requirement 11.4 item 5.
           FIXME: it seems that we are not wait long enough, some blocks are not
           erased fully */
        DoC_Command(docptr, NAND_CMD_STATUS, CDSN_CTRL_WP);
        dummy = ReadDOC(docptr, ReadPipeInit);
        DoC_Delay(docptr, 2);
        if (ReadDOC(docptr, Mil_CDSN_IO) & 1) {
                printk("Error Erasing at 0x%x\n", ofs);
                /* There was an error
                   FIXME: implement Bad Block Replacement (in nftl.c ??) */
                instr->state = MTD_ERASE_FAILED;
        } else
                instr->state = MTD_ERASE_DONE;
        dummy = ReadDOC(docptr, LastDataRead);

        mtd_erase_callback(instr);

        return 0;
}

/****************************************************************************
 *
 * Module stuff
 *
 ****************************************************************************/

static void __exit cleanup_doc2001(void)
{
        struct mtd_info *mtd;
        struct DiskOnChip *this;

        while ((mtd=docmillist)) {
                this = mtd->priv;
                docmillist = this->nextdoc;

                del_mtd_device(mtd);

                iounmap(this->virtadr);
                kfree(this->chips);
                kfree(mtd);
        }
}

module_exit(cleanup_doc2001);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org> et al.");
MODULE_DESCRIPTION("Alternative driver for DiskOnChip Millennium");