Linux 2.6.19-rc1

[linux-2.6/next.git] / drivers / mtd / devices / doc2001plus.c

/*
 * Linux driver for Disk-On-Chip Millennium Plus
 *
 * (c) 2002-2003 Greg Ungerer <gerg@snapgear.com>
 * (c) 2002-2003 SnapGear Inc
 * (c) 1999 Machine Vision Holdings, Inc.
 * (c) 1999, 2000 David Woodhouse <dwmw2@infradead.org>
 *
 * $Id: doc2001plus.c,v 1.14 2005/11/07 11:14:24 gleixner Exp $
 *
 * Released under GPL
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/sched.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 *docmilpluslist = NULL;


/* Perform the required delay cycles by writing to the NOP register */
static void DoC_Delay(void __iomem * docptr, int cycles)
{
        int i;

        for (i = 0; (i < cycles); i++)
                WriteDOC(0, docptr, Mplus_NOP);
}

#define CDSN_CTRL_FR_B_MASK     (CDSN_CTRL_FR_B0 | CDSN_CTRL_FR_B1)

/* DOC_WaitReady: Wait for RDY line to be asserted by the flash chip */
static int _DoC_WaitReady(void __iomem * docptr)
{
        unsigned int 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, Mplus_FlashControl) & CDSN_CTRL_FR_B_MASK) != CDSN_CTRL_FR_B_MASK) && --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;

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

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

        return ret;
}

/* For some reason the Millennium Plus seems to occassionally put itself
 * into reset mode. For me this happens randomly, with no pattern that I
 * can detect. M-systems suggest always check this on any block level
 * operation and setting to normal mode if in reset mode.
 */
static inline void DoC_CheckASIC(void __iomem * docptr)
{
        /* Make sure the DoC is in normal mode */
        if ((ReadDOC(docptr, Mplus_DOCControl) & DOC_MODE_NORMAL) == 0) {
                WriteDOC((DOC_MODE_NORMAL | DOC_MODE_MDWREN), docptr, Mplus_DOCControl);
                WriteDOC(~(DOC_MODE_NORMAL | DOC_MODE_MDWREN), docptr, Mplus_CtrlConfirm);
        }
}

/* DoC_Command: Send a flash command to the flash chip through the Flash
 * command register. Need 2 Write Pipeline Terminates to complete send.
 */
static void DoC_Command(void __iomem * docptr, unsigned char command,
                               unsigned char xtraflags)
{
        WriteDOC(command, docptr, Mplus_FlashCmd);
        WriteDOC(command, docptr, Mplus_WritePipeTerm);
        WriteDOC(command, docptr, Mplus_WritePipeTerm);
}

/* DoC_Address: Set the current address for the flash chip through the Flash
 * Address register. Need 2 Write Pipeline Terminates to complete send.
 */
static inline void DoC_Address(struct DiskOnChip *doc, int numbytes,
                               unsigned long ofs, unsigned char xtraflags1,
                               unsigned char xtraflags2)
{
        void __iomem * docptr = doc->virtadr;

        /* Allow for possible Mill Plus internal flash interleaving */
        ofs >>= doc->interleave;

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

        WriteDOC(0x00, docptr, Mplus_WritePipeTerm);
        WriteDOC(0x00, docptr, Mplus_WritePipeTerm);
}

/* DoC_SelectChip: Select a given flash chip within the current floor */
static int DoC_SelectChip(void __iomem * docptr, int chip)
{
        /* No choice for flash chip on Millennium Plus */
        return 0;
}

/* DoC_SelectFloor: Select a given floor (bank of flash chips) */
static int DoC_SelectFloor(void __iomem * docptr, int floor)
{
        WriteDOC((floor & 0x3), docptr, Mplus_DeviceSelect);
        return 0;
}

/*
 * Translate the given offset into the appropriate command and offset.
 * This does the mapping using the 16bit interleave layout defined by
 * M-Systems, and looks like this for a sector pair:
 *  +-----------+-------+-------+-------+--------------+---------+-----------+
 *  | 0 --- 511 |512-517|518-519|520-521| 522 --- 1033 |1034-1039|1040 - 1055|
 *  +-----------+-------+-------+-------+--------------+---------+-----------+
 *  | Data 0    | ECC 0 |Flags0 |Flags1 | Data 1       |ECC 1    | OOB 1 + 2 |
 *  +-----------+-------+-------+-------+--------------+---------+-----------+
 */
/* FIXME: This lives in INFTL not here. Other users of flash devices
   may not want it */
static unsigned int DoC_GetDataOffset(struct mtd_info *mtd, loff_t *from)
{
        struct DiskOnChip *this = mtd->priv;

        if (this->interleave) {
                unsigned int ofs = *from & 0x3ff;
                unsigned int cmd;

                if (ofs < 512) {
                        cmd = NAND_CMD_READ0;
                        ofs &= 0x1ff;
                } else if (ofs < 1014) {
                        cmd = NAND_CMD_READ1;
                        ofs = (ofs & 0x1ff) + 10;
                } else {
                        cmd = NAND_CMD_READOOB;
                        ofs = ofs - 1014;
                }

                *from = (*from & ~0x3ff) | ofs;
                return cmd;
        } else {
                /* No interleave */
                if ((*from) & 0x100)
                        return NAND_CMD_READ1;
                return NAND_CMD_READ0;
        }
}

static unsigned int DoC_GetECCOffset(struct mtd_info *mtd, loff_t *from)
{
        unsigned int ofs, cmd;

        if (*from & 0x200) {
                cmd = NAND_CMD_READOOB;
                ofs = 10 + (*from & 0xf);
        } else {
                cmd = NAND_CMD_READ1;
                ofs = (*from & 0xf);
        }

        *from = (*from & ~0x3ff) | ofs;
        return cmd;
}

static unsigned int DoC_GetFlagsOffset(struct mtd_info *mtd, loff_t *from)
{
        unsigned int ofs, cmd;

        cmd = NAND_CMD_READ1;
        ofs = (*from & 0x200) ? 8 : 6;
        *from = (*from & ~0x3ff) | ofs;
        return cmd;
}

static unsigned int DoC_GetHdrOffset(struct mtd_info *mtd, loff_t *from)
{
        unsigned int ofs, cmd;

        cmd = NAND_CMD_READOOB;
        ofs = (*from & 0x200) ? 24 : 16;
        *from = (*from & ~0x3ff) | ofs;
        return cmd;
}

static inline void MemReadDOC(void __iomem * docptr, unsigned char *buf, int len)
{
#ifndef USE_MEMCPY
        int i;
        for (i = 0; i < len; i++)
                buf[i] = ReadDOC(docptr, Mil_CDSN_IO + i);
#else
        memcpy_fromio(buf, docptr + DoC_Mil_CDSN_IO, len);
#endif
}

static inline void MemWriteDOC(void __iomem * docptr, unsigned char *buf, int len)
{
#ifndef USE_MEMCPY
        int i;
        for (i = 0; i < len; i++)
                WriteDOC(buf[i], docptr, Mil_CDSN_IO + i);
#else
        memcpy_toio(docptr + DoC_Mil_CDSN_IO, buf, len);
#endif
}

/* 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;
        void __iomem * docptr = doc->virtadr;

        /* Page in the required floor/chip */
        DoC_SelectFloor(docptr, floor);
        DoC_SelectChip(docptr, chip);

        /* Millennium Plus bus cycle sequence as per figure 2, section 2.4 */
        WriteDOC((DOC_FLASH_CE | DOC_FLASH_WP), docptr, Mplus_FlashSelect);

        /* Reset the chip, see Software Requirement 11.4 item 1. */
        DoC_Command(docptr, NAND_CMD_RESET, 0);
        DoC_WaitReady(docptr);

        /* Read the NAND chip ID: 1. Send ReadID command */
        DoC_Command(docptr, NAND_CMD_READID, 0);

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

        WriteDOC(0, docptr, Mplus_FlashControl);
        DoC_WaitReady(docptr);

        /* Read the manufacturer and device id codes of the flash device through
           CDSN IO register see Software Requirement 11.4 item 5.*/
        dummy = ReadDOC(docptr, Mplus_ReadPipeInit);
        dummy = ReadDOC(docptr, Mplus_ReadPipeInit);

        mfr = ReadDOC(docptr, Mil_CDSN_IO);
        if (doc->interleave)
                dummy = ReadDOC(docptr, Mil_CDSN_IO); /* 2 way interleave */

        id  = ReadDOC(docptr, Mil_CDSN_IO);
        if (doc->interleave)
                dummy = ReadDOC(docptr, Mil_CDSN_IO); /* 2 way interleave */

        dummy = ReadDOC(docptr, Mplus_LastDataRead);
        dummy = ReadDOC(docptr, Mplus_LastDataRead);

        /* Disable flash internally */
        WriteDOC(0, docptr, Mplus_FlashSelect);

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

        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;
                        doc->erasesize = nand_flash_ids[i].erasesize << doc->interleave;
                        break;
                }
        }

        if (nand_flash_ids[i].name == NULL)
                return 0;
        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_MPLUS];
        int ret;

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

        /* Work out the intended interleave setting */
        this->interleave = 0;
        if (this->ChipID == DOC_ChipID_DocMilPlus32)
                this->interleave = 1;

        /* Check the ASIC agrees */
        if ( (this->interleave << 2) !=
             (ReadDOC(this->virtadr, Mplus_Configuration) & 4)) {
                u_char conf = ReadDOC(this->virtadr, Mplus_Configuration);
                printk(KERN_NOTICE "Setting DiskOnChip Millennium Plus interleave to %s\n",
                       this->interleave?"on (16-bit)":"off (8-bit)");
                conf ^= 4;
                WriteDOC(conf, this->virtadr, Mplus_Configuration);
        }

        /* For each floor, find the number of valid chips it contains */
        for (floor = 0,ret = 1; floor < MAX_FLOORS_MPLUS; floor++) {
                numchips[floor] = 0;
                for (chip = 0; chip < MAX_CHIPS_MPLUS && 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("MTD: 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_MPLUS; 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 DoCMilPlus_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 Millennium docs), but it seems to work. */
        tmp1 = ReadDOC(doc1->virtadr, Mplus_AliasResolution);
        tmp2 = ReadDOC(doc2->virtadr, Mplus_AliasResolution);
        if (tmp1 != tmp2)
                return 0;

        WriteDOC((tmp1+1) % 0xff, doc1->virtadr, Mplus_AliasResolution);
        tmp2 = ReadDOC(doc2->virtadr, Mplus_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, Mplus_AliasResolution);

        return retval;
}

/* This routine is found from the docprobe code by symbol_get(),
 * which will bump the use count of this module. */
void DoCMilPlus_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 (docmilpluslist)
                old = docmilpluslist->priv;

        while (old) {
                if (DoCMilPlus_is_alias(this, old)) {
                        printk(KERN_NOTICE "Ignoring DiskOnChip Millennium "
                                "Plus 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 Plus";
        printk(KERN_NOTICE "DiskOnChip Millennium Plus found at "
                "address 0x%lX\n", this->physadr);

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

        mtd->erasesize = 0;
        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 = docmilpluslist;
                docmilpluslist = mtd;
                mtd->size  = this->totlen;
                mtd->erasesize = this->erasesize;
                add_mtd_device(mtd);
                return;
        }
}
EXPORT_SYMBOL_GPL(DoCMilPlus_init);

#if 0
static int doc_dumpblk(struct mtd_info *mtd, loff_t from)
{
        int i;
        loff_t fofs;
        struct DiskOnChip *this = mtd->priv;
        void __iomem * docptr = this->virtadr;
        struct Nand *mychip = &this->chips[from >> (this->chipshift)];
        unsigned char *bp, buf[1056];
        char c[32];

        from &= ~0x3ff;

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

        DoC_CheckASIC(docptr);

        /* 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;

        /* Millennium Plus bus cycle sequence as per figure 2, section 2.4 */
        WriteDOC((DOC_FLASH_CE | DOC_FLASH_WP), docptr, Mplus_FlashSelect);

        /* Reset the chip, see Software Requirement 11.4 item 1. */
        DoC_Command(docptr, NAND_CMD_RESET, 0);
        DoC_WaitReady(docptr);

        fofs = from;
        DoC_Command(docptr, DoC_GetDataOffset(mtd, &fofs), 0);
        DoC_Address(this, 3, fofs, 0, 0x00);
        WriteDOC(0, docptr, Mplus_FlashControl);
        DoC_WaitReady(docptr);

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

        ReadDOC(docptr, Mplus_ReadPipeInit);
        ReadDOC(docptr, Mplus_ReadPipeInit);

        /* Read the data via the internal pipeline through CDSN IO
           register, see Pipelined Read Operations 11.3 */
        MemReadDOC(docptr, buf, 1054);
        buf[1054] = ReadDOC(docptr, Mplus_LastDataRead);
        buf[1055] = ReadDOC(docptr, Mplus_LastDataRead);

        memset(&c[0], 0, sizeof(c));
        printk("DUMP OFFSET=%x:\n", (int)from);

        for (i = 0, bp = &buf[0]; (i < 1056); i++) {
                if ((i % 16) == 0)
                        printk("%08x: ", i);
                printk(" %02x", *bp);
                c[(i & 0xf)] = ((*bp >= 0x20) && (*bp <= 0x7f)) ? *bp : '.';
                bp++;
                if (((i + 1) % 16) == 0)
                        printk("    %s\n", c);
        }
        printk("\n");

        /* Disable flash internally */
        WriteDOC(0, docptr, Mplus_FlashSelect);

        return 0;
}
#endif

static int doc_read(struct mtd_info *mtd, loff_t from, size_t len,
                    size_t *retlen, u_char *buf)
{
        int ret, i;
        volatile char dummy;
        loff_t fofs;
        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;

        DoC_CheckASIC(docptr);

        /* 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;

        /* Millennium Plus bus cycle sequence as per figure 2, section 2.4 */
        WriteDOC((DOC_FLASH_CE | DOC_FLASH_WP), docptr, Mplus_FlashSelect);

        /* Reset the chip, see Software Requirement 11.4 item 1. */
        DoC_Command(docptr, NAND_CMD_RESET, 0);
        DoC_WaitReady(docptr);

        fofs = from;
        DoC_Command(docptr, DoC_GetDataOffset(mtd, &fofs), 0);
        DoC_Address(this, 3, fofs, 0, 0x00);
        WriteDOC(0, docptr, Mplus_FlashControl);
        DoC_WaitReady(docptr);

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

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

        ReadDOC(docptr, Mplus_ReadPipeInit);
        ReadDOC(docptr, Mplus_ReadPipeInit);

        /* Read the data via the internal pipeline through CDSN IO
           register, see Pipelined Read Operations 11.3 */
        MemReadDOC(docptr, buf, len);

        /* Read the ECC data following raw data */
        MemReadDOC(docptr, eccbuf, 4);
        eccbuf[4] = ReadDOC(docptr, Mplus_LastDataRead);
        eccbuf[5] = ReadDOC(docptr, Mplus_LastDataRead);

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

        /* Check the ECC Status */
        if (ReadDOC(docptr, Mplus_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, Mplus_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 */
#ifdef ECC_DEBUG
                        printk("%s(%d): Millennium Plus ECC error (from=0x%x:\n",
                                __FILE__, __LINE__, (int)from);
                        printk("        syndrome= %02x:%02x:%02x:%02x:%02x:"
                                "%02x\n",
                                syndrome[0], syndrome[1], syndrome[2],
                                syndrome[3], syndrome[4], syndrome[5]);
                        printk("          eccbuf= %02x:%02x:%02x:%02x:%02x:"
                                "%02x\n",
                                eccbuf[0], eccbuf[1], eccbuf[2],
                                eccbuf[3], eccbuf[4], eccbuf[5]);
#endif
                                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 , Mplus_ECCConf);

        /* Disable flash internally */
        WriteDOC(0, docptr, Mplus_FlashSelect);

        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, before, ret = 0;
        loff_t fto;
        volatile char dummy;
        char eccbuf[6];
        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;

        /* Don't allow writes which aren't exactly one block (512 bytes) */
        if ((to & 0x1ff) || (len != 0x200))
                return -EINVAL;

        /* Determine position of OOB flags, before or after data */
        before = (this->interleave && (to & 0x200));

        DoC_CheckASIC(docptr);

        /* 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;

        /* Millennium Plus bus cycle sequence as per figure 2, section 2.4 */
        WriteDOC(DOC_FLASH_CE, docptr, Mplus_FlashSelect);

        /* Reset the chip, see Software Requirement 11.4 item 1. */
        DoC_Command(docptr, NAND_CMD_RESET, 0);
        DoC_WaitReady(docptr);

        /* Set device to appropriate plane of flash */
        fto = to;
        WriteDOC(DoC_GetDataOffset(mtd, &fto), docptr, Mplus_FlashCmd);

        /* On interleaved devices the flags for 2nd half 512 are before data */
        if (eccbuf && before)
                fto -= 2;

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

        /* Disable the ECC engine */
        WriteDOC(DOC_ECC_RESET, docptr, Mplus_ECCConf);

        if (before) {
                /* Write the block status BLOCK_USED (0x5555) */
                WriteDOC(0x55, docptr, Mil_CDSN_IO);
                WriteDOC(0x55, docptr, Mil_CDSN_IO);
        }

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

        MemWriteDOC(docptr, (unsigned char *) buf, len);

        /* Write ECC data to flash, the ECC info is generated by
           the DiskOnChip ECC logic see Reed-Solomon EDC/ECC 11.1 */
        DoC_Delay(docptr, 3);

        /* Read the ECC data through the DiskOnChip ECC logic */
        for (i = 0; i < 6; i++)
                eccbuf[i] = ReadDOC(docptr, Mplus_ECCSyndrome0 + i);

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

        /* Write the ECC data to flash */
        MemWriteDOC(docptr, eccbuf, 6);

        if (!before) {
                /* Write the block status BLOCK_USED (0x5555) */
                WriteDOC(0x55, docptr, Mil_CDSN_IO+6);
                WriteDOC(0x55, docptr, Mil_CDSN_IO+7);
        }

#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

        WriteDOC(0x00, docptr, Mplus_WritePipeTerm);
        WriteDOC(0x00, docptr, Mplus_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, 0);
        dummy = ReadDOC(docptr, Mplus_ReadPipeInit);
        dummy = ReadDOC(docptr, Mplus_ReadPipeInit);
        DoC_Delay(docptr, 2);
        if ((dummy = ReadDOC(docptr, Mplus_LastDataRead)) & 1) {
                printk("MTD: Error 0x%x programming at 0x%x\n", dummy, (int)to);
                /* Error in programming
                   FIXME: implement Bad Block Replacement (in nftl.c ??) */
                *retlen = 0;
                ret = -EIO;
        }
        dummy = ReadDOC(docptr, Mplus_LastDataRead);

        /* Disable flash internally */
        WriteDOC(0, docptr, Mplus_FlashSelect);

        /* 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)
{
        loff_t fofs, base;
        struct DiskOnChip *this = mtd->priv;
        void __iomem * docptr = this->virtadr;
        struct Nand *mychip = &this->chips[ofs >> this->chipshift];
        size_t i, size, got, want;
        uint8_t *buf = ops->oobbuf;
        size_t len = ops->len;

        BUG_ON(ops->mode != MTD_OOB_PLACE);

        ofs += ops->ooboffs;

        DoC_CheckASIC(docptr);

        /* 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;

        /* Millennium Plus bus cycle sequence as per figure 2, section 2.4 */
        WriteDOC((DOC_FLASH_CE | DOC_FLASH_WP), docptr, Mplus_FlashSelect);

        /* disable the ECC engine */
        WriteDOC(DOC_ECC_RESET, docptr, Mplus_ECCConf);
        DoC_WaitReady(docptr);

        /* Maximum of 16 bytes in the OOB region, so limit read to that */
        if (len > 16)
                len = 16;
        got = 0;
        want = len;

        for (i = 0; ((i < 3) && (want > 0)); i++) {
                /* Figure out which region we are accessing... */
                fofs = ofs;
                base = ofs & 0xf;
                if (!this->interleave) {
                        DoC_Command(docptr, NAND_CMD_READOOB, 0);
                        size = 16 - base;
                } else if (base < 6) {
                        DoC_Command(docptr, DoC_GetECCOffset(mtd, &fofs), 0);
                        size = 6 - base;
                } else if (base < 8) {
                        DoC_Command(docptr, DoC_GetFlagsOffset(mtd, &fofs), 0);
                        size = 8 - base;
                } else {
                        DoC_Command(docptr, DoC_GetHdrOffset(mtd, &fofs), 0);
                        size = 16 - base;
                }
                if (size > want)
                        size = want;

                /* Issue read command */
                DoC_Address(this, 3, fofs, 0, 0x00);
                WriteDOC(0, docptr, Mplus_FlashControl);
                DoC_WaitReady(docptr);

                ReadDOC(docptr, Mplus_ReadPipeInit);
                ReadDOC(docptr, Mplus_ReadPipeInit);
                MemReadDOC(docptr, &buf[got], size - 2);
                buf[got + size - 2] = ReadDOC(docptr, Mplus_LastDataRead);
                buf[got + size - 1] = ReadDOC(docptr, Mplus_LastDataRead);

                ofs += size;
                got += size;
                want -= size;
        }

        /* Disable flash internally */
        WriteDOC(0, docptr, Mplus_FlashSelect);

        ops->retlen = len;
        return 0;
}

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

        BUG_ON(ops->mode != MTD_OOB_PLACE);

        ofs += ops->ooboffs;

        DoC_CheckASIC(docptr);

        /* 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;

        /* Millennium Plus bus cycle sequence as per figure 2, section 2.4 */
        WriteDOC(DOC_FLASH_CE, docptr, Mplus_FlashSelect);


        /* Maximum of 16 bytes in the OOB region, so limit write to that */
        if (len > 16)
                len = 16;
        got = 0;
        want = len;

        for (i = 0; ((i < 3) && (want > 0)); i++) {
                /* Reset the chip, see Software Requirement 11.4 item 1. */
                DoC_Command(docptr, NAND_CMD_RESET, 0);
                DoC_WaitReady(docptr);

                /* Figure out which region we are accessing... */
                fofs = ofs;
                base = ofs & 0x0f;
                if (!this->interleave) {
                        WriteDOC(NAND_CMD_READOOB, docptr, Mplus_FlashCmd);
                        size = 16 - base;
                } else if (base < 6) {
                        WriteDOC(DoC_GetECCOffset(mtd, &fofs), docptr, Mplus_FlashCmd);
                        size = 6 - base;
                } else if (base < 8) {
                        WriteDOC(DoC_GetFlagsOffset(mtd, &fofs), docptr, Mplus_FlashCmd);
                        size = 8 - base;
                } else {
                        WriteDOC(DoC_GetHdrOffset(mtd, &fofs), docptr, Mplus_FlashCmd);
                        size = 16 - base;
                }
                if (size > want)
                        size = want;

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

                /* Disable the ECC engine */
                WriteDOC(DOC_ECC_RESET, docptr, Mplus_ECCConf);

                /* Write the data via the internal pipeline through CDSN IO
                   register, see Pipelined Write Operations 11.2 */
                MemWriteDOC(docptr, (unsigned char *) &buf[got], size);
                WriteDOC(0x00, docptr, Mplus_WritePipeTerm);
                WriteDOC(0x00, docptr, Mplus_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, Mplus_ReadPipeInit);
                dummy = ReadDOC(docptr, Mplus_ReadPipeInit);
                DoC_Delay(docptr, 2);
                if ((dummy = ReadDOC(docptr, Mplus_LastDataRead)) & 1) {
                        printk("MTD: Error 0x%x programming oob at 0x%x\n",
                                dummy, (int)ofs);
                        /* FIXME: implement Bad Block Replacement */
                        ops->retlen = 0;
                        ret = -EIO;
                }
                dummy = ReadDOC(docptr, Mplus_LastDataRead);

                ofs += size;
                got += size;
                want -= size;
        }

        /* Disable flash internally */
        WriteDOC(0, docptr, Mplus_FlashSelect);

        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];

        DoC_CheckASIC(docptr);

        if (len != mtd->erasesize)
                printk(KERN_WARNING "MTD: 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;

        /* Millennium Plus bus cycle sequence as per figure 2, section 2.4 */
        WriteDOC(DOC_FLASH_CE, docptr, Mplus_FlashSelect);

        DoC_Command(docptr, NAND_CMD_RESET, 0x00);
        DoC_WaitReady(docptr);

        DoC_Command(docptr, NAND_CMD_ERASE1, 0);
        DoC_Address(this, 2, ofs, 0, 0x00);
        DoC_Command(docptr, NAND_CMD_ERASE2, 0);
        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. */
        DoC_Command(docptr, NAND_CMD_STATUS, 0);
        dummy = ReadDOC(docptr, Mplus_ReadPipeInit);
        dummy = ReadDOC(docptr, Mplus_ReadPipeInit);
        if ((dummy = ReadDOC(docptr, Mplus_LastDataRead)) & 1) {
                printk("MTD: Error 0x%x erasing at 0x%x\n", dummy, ofs);
                /* FIXME: implement Bad Block Replacement (in nftl.c ??) */
                instr->state = MTD_ERASE_FAILED;
        } else {
                instr->state = MTD_ERASE_DONE;
        }
        dummy = ReadDOC(docptr, Mplus_LastDataRead);

        /* Disable flash internally */
        WriteDOC(0, docptr, Mplus_FlashSelect);

        mtd_erase_callback(instr);

        return 0;
}

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

static void __exit cleanup_doc2001plus(void)
{
        struct mtd_info *mtd;
        struct DiskOnChip *this;

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

                del_mtd_device(mtd);

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

module_exit(cleanup_doc2001plus);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Greg Ungerer <gerg@snapgear.com> et al.");
MODULE_DESCRIPTION("Driver for DiskOnChip Millennium Plus");