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[pohmelfs.git] / drivers / mtd / devices / doc2000.c

/*
 * Linux driver for Disk-On-Chip 2000 and 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/sched.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/mutex.h>

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

#define DOC_SUPPORT_2000
#define DOC_SUPPORT_2000TSOP
#define DOC_SUPPORT_MILLENNIUM

#ifdef DOC_SUPPORT_2000
#define DoC_is_2000(doc) (doc->ChipID == DOC_ChipID_Doc2k)
#else
#define DoC_is_2000(doc) (0)
#endif

#if defined(DOC_SUPPORT_2000TSOP) || defined(DOC_SUPPORT_MILLENNIUM)
#define DoC_is_Millennium(doc) (doc->ChipID == DOC_ChipID_DocMil)
#else
#define DoC_is_Millennium(doc) (0)
#endif

/* #define ECC_DEBUG */

/* I have no idea why some DoC chips can not use memcpy_from|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_write_oob_nolock(struct mtd_info *mtd, loff_t ofs, size_t len,
                         size_t *retlen, const u_char *buf);
static int doc_erase (struct mtd_info *mtd, struct erase_info *instr);

static struct mtd_info *doc2klist = NULL;

/* Perform the required delay cycles by reading from the appropriate register */
static void DoC_Delay(struct DiskOnChip *doc, unsigned short cycles)
{
        volatile char dummy;
        int i;

        for (i = 0; i < cycles; i++) {
                if (DoC_is_Millennium(doc))
                        dummy = ReadDOC(doc->virtadr, NOP);
                else
                        dummy = ReadDOC(doc->virtadr, DOCStatus);
        }

}

/* DOC_WaitReady: Wait for RDY line to be asserted by the flash chip */
static int _DoC_WaitReady(struct DiskOnChip *doc)
{
        void __iomem *docptr = doc->virtadr;
        unsigned long timeo = jiffies + (HZ * 10);

        pr_debug("_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)) {
                /* issue 2 read from NOP register after reading from CDSNControl register
                see Software Requirement 11.4 item 2. */
                DoC_Delay(doc, 2);

                if (time_after(jiffies, timeo)) {
                        pr_debug("_DoC_WaitReady timed out.\n");
                        return -EIO;
                }
                udelay(1);
                cond_resched();
        }

        return 0;
}

static inline int DoC_WaitReady(struct DiskOnChip *doc)
{
        void __iomem *docptr = doc->virtadr;

        /* 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(doc, 4);

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

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

        return ret;
}

/* DoC_Command: Send a flash command to the flash chip through the CDSN Slow IO register to
   bypass 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 int DoC_Command(struct DiskOnChip *doc, unsigned char command,
                              unsigned char xtraflags)
{
        void __iomem *docptr = doc->virtadr;

        if (DoC_is_2000(doc))
                xtraflags |= CDSN_CTRL_FLASH_IO;

        /* Assert the CLE (Command Latch Enable) line to the flash chip */
        WriteDOC(xtraflags | CDSN_CTRL_CLE | CDSN_CTRL_CE, docptr, CDSNControl);
        DoC_Delay(doc, 4);      /* Software requirement 11.4.3 for Millennium */

        if (DoC_is_Millennium(doc))
                WriteDOC(command, docptr, CDSNSlowIO);

        /* Send the command */
        WriteDOC_(command, docptr, doc->ioreg);
        if (DoC_is_Millennium(doc))
                WriteDOC(command, docptr, WritePipeTerm);

        /* Lower the CLE line */
        WriteDOC(xtraflags | CDSN_CTRL_CE, docptr, CDSNControl);
        DoC_Delay(doc, 4);      /* Software requirement 11.4.3 for Millennium */

        /* Wait for the chip to respond - Software requirement 11.4.1 (extended for any command) */
        return DoC_WaitReady(doc);
}

/* DoC_Address: Set the current address for the flash chip through the CDSN Slow IO register to
   bypass 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 int DoC_Address(struct DiskOnChip *doc, int numbytes, unsigned long ofs,
                       unsigned char xtraflags1, unsigned char xtraflags2)
{
        int i;
        void __iomem *docptr = doc->virtadr;

        if (DoC_is_2000(doc))
                xtraflags1 |= CDSN_CTRL_FLASH_IO;

        /* Assert the ALE (Address Latch Enable) line to the flash chip */
        WriteDOC(xtraflags1 | CDSN_CTRL_ALE | CDSN_CTRL_CE, docptr, CDSNControl);

        DoC_Delay(doc, 4);      /* Software requirement 11.4.3 for Millennium */

        /* Send the address */
        /* Devices with 256-byte page are addressed as:
           Column (bits 0-7), Page (bits 8-15, 16-23, 24-31)
           * there is no device on the market with page256
           and more than 24 bits.
           Devices with 512-byte page are addressed as:
           Column (bits 0-7), Page (bits 9-16, 17-24, 25-31)
           * 25-31 is sent only if the chip support it.
           * bit 8 changes the read command to be sent
           (NAND_CMD_READ0 or NAND_CMD_READ1).
         */

        if (numbytes == ADDR_COLUMN || numbytes == ADDR_COLUMN_PAGE) {
                if (DoC_is_Millennium(doc))
                        WriteDOC(ofs & 0xff, docptr, CDSNSlowIO);
                WriteDOC_(ofs & 0xff, docptr, doc->ioreg);
        }

        if (doc->page256) {
                ofs = ofs >> 8;
        } else {
                ofs = ofs >> 9;
        }

        if (numbytes == ADDR_PAGE || numbytes == ADDR_COLUMN_PAGE) {
                for (i = 0; i < doc->pageadrlen; i++, ofs = ofs >> 8) {
                        if (DoC_is_Millennium(doc))
                                WriteDOC(ofs & 0xff, docptr, CDSNSlowIO);
                        WriteDOC_(ofs & 0xff, docptr, doc->ioreg);
                }
        }

        if (DoC_is_Millennium(doc))
                WriteDOC(ofs & 0xff, docptr, WritePipeTerm);

        DoC_Delay(doc, 2);      /* Needed for some slow flash chips. mf. */

        /* FIXME: The SlowIO's for millennium could be replaced by
           a single WritePipeTerm here. mf. */

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

        DoC_Delay(doc, 4);      /* Software requirement 11.4.3 for Millennium */

        /* Wait for the chip to respond - Software requirement 11.4.1 */
        return DoC_WaitReady(doc);
}

/* Read a buffer from DoC, taking care of Millennium odditys */
static void DoC_ReadBuf(struct DiskOnChip *doc, u_char * buf, int len)
{
        volatile int dummy;
        int modulus = 0xffff;
        void __iomem *docptr = doc->virtadr;
        int i;

        if (len <= 0)
                return;

        if (DoC_is_Millennium(doc)) {
                /* Read the data via the internal pipeline through CDSN IO register,
                   see Pipelined Read Operations 11.3 */
                dummy = ReadDOC(docptr, ReadPipeInit);

                /* Millennium should use the LastDataRead register - Pipeline Reads */
                len--;

                /* This is needed for correctly ECC calculation */
                modulus = 0xff;
        }

        for (i = 0; i < len; i++)
                buf[i] = ReadDOC_(docptr, doc->ioreg + (i & modulus));

        if (DoC_is_Millennium(doc)) {
                buf[i] = ReadDOC(docptr, LastDataRead);
        }
}

/* Write a buffer to DoC, taking care of Millennium odditys */
static void DoC_WriteBuf(struct DiskOnChip *doc, const u_char * buf, int len)
{
        void __iomem *docptr = doc->virtadr;
        int i;

        if (len <= 0)
                return;

        for (i = 0; i < len; i++)
                WriteDOC_(buf[i], docptr, doc->ioreg + i);

        if (DoC_is_Millennium(doc)) {
                WriteDOC(0x00, docptr, WritePipeTerm);
        }
}


/* DoC_SelectChip: Select a given flash chip within the current floor */

static inline int DoC_SelectChip(struct DiskOnChip *doc, int chip)
{
        void __iomem *docptr = doc->virtadr;

        /* Software requirement 11.4.4 before writing DeviceSelect */
        /* Deassert the CE line to eliminate glitches on the FCE# outputs */
        WriteDOC(CDSN_CTRL_WP, docptr, CDSNControl);
        DoC_Delay(doc, 4);      /* Software requirement 11.4.3 for Millennium */

        /* Select the individual flash chip requested */
        WriteDOC(chip, docptr, CDSNDeviceSelect);
        DoC_Delay(doc, 4);

        /* Reassert the CE line */
        WriteDOC(CDSN_CTRL_CE | CDSN_CTRL_FLASH_IO | CDSN_CTRL_WP, docptr,
                 CDSNControl);
        DoC_Delay(doc, 4);      /* Software requirement 11.4.3 for Millennium */

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

/* DoC_SelectFloor: Select a given floor (bank of flash chips) */

static inline int DoC_SelectFloor(struct DiskOnChip *doc, int floor)
{
        void __iomem *docptr = doc->virtadr;

        /* Select the floor (bank) of chips required */
        WriteDOC(floor, docptr, FloorSelect);

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

/* 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 */
        DoC_SelectFloor(doc, floor);
        DoC_SelectChip(doc, chip);

        /* Reset the chip */
        if (DoC_Command(doc, NAND_CMD_RESET, CDSN_CTRL_WP)) {
                pr_debug("DoC_Command (reset) for %d,%d returned true\n",
                      floor, chip);
                return 0;
        }


        /* Read the NAND chip ID: 1. Send ReadID command */
        if (DoC_Command(doc, NAND_CMD_READID, CDSN_CTRL_WP)) {
                pr_debug("DoC_Command (ReadID) for %d,%d returned true\n",
                      floor, chip);
                return 0;
        }

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

        /* Read the manufacturer and device id codes from the device */

        if (DoC_is_Millennium(doc)) {
                DoC_Delay(doc, 2);
                dummy = ReadDOC(doc->virtadr, ReadPipeInit);
                mfr = ReadDOC(doc->virtadr, LastDataRead);

                DoC_Delay(doc, 2);
                dummy = ReadDOC(doc->virtadr, ReadPipeInit);
                id = ReadDOC(doc->virtadr, LastDataRead);
        } else {
                /* CDSN Slow IO register see Software Req 11.4 item 5. */
                dummy = ReadDOC(doc->virtadr, CDSNSlowIO);
                DoC_Delay(doc, 2);
                mfr = ReadDOC_(doc->virtadr, doc->ioreg);

                /* CDSN Slow IO register see Software Req 11.4 item 5. */
                dummy = ReadDOC(doc->virtadr, CDSNSlowIO);
                DoC_Delay(doc, 2);
                id = ReadDOC_(doc->virtadr, doc->ioreg);
        }

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

        /* Check it's the same as the first chip we identified.
         * M-Systems say that any given DiskOnChip device should only
         * contain _one_ type of flash part, although that's not a
         * hardware restriction. */
        if (doc->mfr) {
                if (doc->mfr == mfr && doc->id == id)
                        return 1;       /* This is the same as the first */
                else
                        printk(KERN_WARNING
                               "Flash chip at floor %d, chip %d is different:\n",
                               floor, chip);
        }

        /* Print and store the manufacturer and ID codes. */
        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);
                        if (!doc->mfr) {
                                doc->mfr = mfr;
                                doc->id = id;
                                doc->chipshift =
                                        ffs((nand_flash_ids[i].chipsize << 20)) - 1;
                                doc->page256 = (nand_flash_ids[i].pagesize == 256) ? 1 : 0;
                                doc->pageadrlen = doc->chipshift > 25 ? 3 : 2;
                                doc->erasesize =
                                    nand_flash_ids[i].erasesize;
                                return 1;
                        }
                        return 0;
                }
        }


        /* We haven't fully identified the chip. Print as much as we know. */
        printk(KERN_WARNING "Unknown flash chip found: %2.2X %2.2X\n",
               id, mfr);

        printk(KERN_WARNING "Please report to dwmw2@infradead.org\n");
        return 0;
}

/* DoC_ScanChips: Find all NAND chips present in a DiskOnChip, and identify them */

static void DoC_ScanChips(struct DiskOnChip *this, int maxchips)
{
        int floor, chip;
        int numchips[MAX_FLOORS];
        int ret = 1;

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

        /* For each floor, find the number of valid chips it contains */
        for (floor = 0; floor < MAX_FLOORS; floor++) {
                ret = 1;
                numchips[floor] = 0;
                for (chip = 0; chip < maxchips && 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(KERN_NOTICE "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(KERN_NOTICE "No memory for allocating chip info structures\n");
                return;
        }

        ret = 0;

        /* Fill out the chip array with {floor, chipno} for each
         * detected chip in the device. */
        for (floor = 0; floor < MAX_FLOORS; 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 DoC2k_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, 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 DoC2k_init(struct mtd_info *mtd)
{
        struct DiskOnChip *this = mtd->priv;
        struct DiskOnChip *old = NULL;
        int maxchips;

        /* We must avoid being called twice for the same device. */

        if (doc2klist)
                old = doc2klist->priv;

        while (old) {
                if (DoC2k_is_alias(old, this)) {
                        printk(KERN_NOTICE
                               "Ignoring DiskOnChip 2000 at 0x%lX - already configured\n",
                               this->physadr);
                        iounmap(this->virtadr);
                        kfree(mtd);
                        return;
                }
                if (old->nextdoc)
                        old = old->nextdoc->priv;
                else
                        old = NULL;
        }


        switch (this->ChipID) {
        case DOC_ChipID_Doc2kTSOP:
                mtd->name = "DiskOnChip 2000 TSOP";
                this->ioreg = DoC_Mil_CDSN_IO;
                /* Pretend it's a Millennium */
                this->ChipID = DOC_ChipID_DocMil;
                maxchips = MAX_CHIPS;
                break;
        case DOC_ChipID_Doc2k:
                mtd->name = "DiskOnChip 2000";
                this->ioreg = DoC_2k_CDSN_IO;
                maxchips = MAX_CHIPS;
                break;
        case DOC_ChipID_DocMil:
                mtd->name = "DiskOnChip Millennium";
                this->ioreg = DoC_Mil_CDSN_IO;
                maxchips = MAX_CHIPS_MIL;
                break;
        default:
                printk("Unknown ChipID 0x%02x\n", this->ChipID);
                kfree(mtd);
                iounmap(this->virtadr);
                return;
        }

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

        mtd->type = MTD_NANDFLASH;
        mtd->flags = MTD_CAP_NANDFLASH;
        mtd->writesize = 512;
        mtd->oobsize = 16;
        mtd->owner = THIS_MODULE;
        mtd->erase = doc_erase;
        mtd->read = doc_read;
        mtd->write = doc_write;
        mtd->read_oob = doc_read_oob;
        mtd->write_oob = doc_write_oob;
        this->curfloor = -1;
        this->curchip = -1;
        mutex_init(&this->lock);

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

        if (!this->totlen) {
                kfree(mtd);
                iounmap(this->virtadr);
        } else {
                this->nextdoc = doc2klist;
                doc2klist = mtd;
                mtd->size = this->totlen;
                mtd->erasesize = this->erasesize;
                mtd_device_register(mtd, NULL, 0);
                return;
        }
}
EXPORT_SYMBOL_GPL(DoC2k_init);

static int doc_read(struct mtd_info *mtd, loff_t from, size_t len,
                    size_t * retlen, u_char * buf)
{
        struct DiskOnChip *this = mtd->priv;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip;
        unsigned char syndrome[6], eccbuf[6];
        volatile char dummy;
        int i, len256 = 0, ret=0;
        size_t left = len;

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

        mutex_lock(&this->lock);

        *retlen = 0;
        while (left) {
                len = left;

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

                /* The ECC will not be calculated correctly if less than 512 is read */
                if (len != 0x200)
                        printk(KERN_WARNING
                               "ECC needs a full sector read (adr: %lx size %lx)\n",
                               (long) from, (long) len);

                /* printk("DoC_Read (adr: %lx size %lx)\n", (long) from, (long) len); */


                /* Find the chip which is to be used and select it */
                mychip = &this->chips[from >> (this->chipshift)];

                if (this->curfloor != mychip->floor) {
                        DoC_SelectFloor(this, mychip->floor);
                        DoC_SelectChip(this, mychip->chip);
                } else if (this->curchip != mychip->chip) {
                        DoC_SelectChip(this, mychip->chip);
                }

                this->curfloor = mychip->floor;
                this->curchip = mychip->chip;

                DoC_Command(this,
                            (!this->page256
                             && (from & 0x100)) ? NAND_CMD_READ1 : NAND_CMD_READ0,
                            CDSN_CTRL_WP);
                DoC_Address(this, ADDR_COLUMN_PAGE, from, CDSN_CTRL_WP,
                            CDSN_CTRL_ECC_IO);

                /* Prime the ECC engine */
                WriteDOC(DOC_ECC_RESET, docptr, ECCConf);
                WriteDOC(DOC_ECC_EN, docptr, ECCConf);

                /* treat crossing 256-byte sector for 2M x 8bits devices */
                if (this->page256 && from + len > (from | 0xff) + 1) {
                        len256 = (from | 0xff) + 1 - from;
                        DoC_ReadBuf(this, buf, len256);

                        DoC_Command(this, NAND_CMD_READ0, CDSN_CTRL_WP);
                        DoC_Address(this, ADDR_COLUMN_PAGE, from + len256,
                                    CDSN_CTRL_WP, CDSN_CTRL_ECC_IO);
                }

                DoC_ReadBuf(this, &buf[len256], len - len256);

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

                /* Read the ECC data through the DiskOnChip ECC logic */
                /* Note: this will work even with 2M x 8bit devices as   */
                /*       they have 8 bytes of OOB per 256 page. mf.      */
                DoC_ReadBuf(this, eccbuf, 6);

                /* Flush the pipeline */
                if (DoC_is_Millennium(this)) {
                        dummy = ReadDOC(docptr, ECCConf);
                        dummy = ReadDOC(docptr, ECCConf);
                        i = ReadDOC(docptr, ECCConf);
                } else {
                        dummy = ReadDOC(docptr, 2k_ECCStatus);
                        dummy = ReadDOC(docptr, 2k_ECCStatus);
                        i = ReadDOC(docptr, 2k_ECCStatus);
                }

                /* Check the ECC Status */
                if (i & 0x80) {
                        int nb_errors;
                        /* There was an ECC error */
#ifdef ECC_DEBUG
                        printk(KERN_ERR "DiskOnChip ECC Error: Read at %lx\n", (long)from);
#endif
                        /* Read the ECC syndrome 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(KERN_ERR "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(KERN_DEBUG "ECC DATA at %lxB: %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);

                /* according to 11.4.1, we need to wait for the busy line
                 * drop if we read to the end of the page.  */
                if(0 == ((from + len) & 0x1ff))
                {
                    DoC_WaitReady(this);
                }

                from += len;
                left -= len;
                buf += len;
        }

        mutex_unlock(&this->lock);

        return ret;
}

static int doc_write(struct mtd_info *mtd, loff_t to, size_t len,
                     size_t * retlen, const u_char * buf)
{
        struct DiskOnChip *this = mtd->priv;
        int di; /* Yes, DI is a hangover from when I was disassembling the binary driver */
        void __iomem *docptr = this->virtadr;
        unsigned char eccbuf[6];
        volatile char dummy;
        int len256 = 0;
        struct Nand *mychip;
        size_t left = len;
        int status;

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

        mutex_lock(&this->lock);

        *retlen = 0;
        while (left) {
                len = left;

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

                /* The ECC will not be calculated correctly if less than 512 is written */
/* DBB-
                if (len != 0x200 && eccbuf)
                        printk(KERN_WARNING
                               "ECC needs a full sector write (adr: %lx size %lx)\n",
                               (long) to, (long) len);
   -DBB */

                /* printk("DoC_Write (adr: %lx size %lx)\n", (long) to, (long) len); */

                /* Find the chip which is to be used and select it */
                mychip = &this->chips[to >> (this->chipshift)];

                if (this->curfloor != mychip->floor) {
                        DoC_SelectFloor(this, mychip->floor);
                        DoC_SelectChip(this, mychip->chip);
                } else if (this->curchip != mychip->chip) {
                        DoC_SelectChip(this, mychip->chip);
                }

                this->curfloor = mychip->floor;
                this->curchip = mychip->chip;

                /* Set device to main plane of flash */
                DoC_Command(this, NAND_CMD_RESET, CDSN_CTRL_WP);
                DoC_Command(this,
                            (!this->page256
                             && (to & 0x100)) ? NAND_CMD_READ1 : NAND_CMD_READ0,
                            CDSN_CTRL_WP);

                DoC_Command(this, NAND_CMD_SEQIN, 0);
                DoC_Address(this, ADDR_COLUMN_PAGE, to, 0, CDSN_CTRL_ECC_IO);

                /* Prime the ECC engine */
                WriteDOC(DOC_ECC_RESET, docptr, ECCConf);
                WriteDOC(DOC_ECC_EN | DOC_ECC_RW, docptr, ECCConf);

                /* treat crossing 256-byte sector for 2M x 8bits devices */
                if (this->page256 && to + len > (to | 0xff) + 1) {
                        len256 = (to | 0xff) + 1 - to;
                        DoC_WriteBuf(this, buf, len256);

                        DoC_Command(this, NAND_CMD_PAGEPROG, 0);

                        DoC_Command(this, NAND_CMD_STATUS, CDSN_CTRL_WP);
                        /* There's an implicit DoC_WaitReady() in DoC_Command */

                        dummy = ReadDOC(docptr, CDSNSlowIO);
                        DoC_Delay(this, 2);

                        if (ReadDOC_(docptr, this->ioreg) & 1) {
                                printk(KERN_ERR "Error programming flash\n");
                                /* Error in programming */
                                *retlen = 0;
                                mutex_unlock(&this->lock);
                                return -EIO;
                        }

                        DoC_Command(this, NAND_CMD_SEQIN, 0);
                        DoC_Address(this, ADDR_COLUMN_PAGE, to + len256, 0,
                                    CDSN_CTRL_ECC_IO);
                }

                DoC_WriteBuf(this, &buf[len256], len - len256);

                WriteDOC(CDSN_CTRL_ECC_IO | CDSN_CTRL_CE, docptr, CDSNControl);

                if (DoC_is_Millennium(this)) {
                        WriteDOC(0, docptr, NOP);
                        WriteDOC(0, docptr, NOP);
                        WriteDOC(0, docptr, NOP);
                } else {
                        WriteDOC_(0, docptr, this->ioreg);
                        WriteDOC_(0, docptr, this->ioreg);
                        WriteDOC_(0, docptr, this->ioreg);
                }

                WriteDOC(CDSN_CTRL_ECC_IO | CDSN_CTRL_FLASH_IO | CDSN_CTRL_CE, docptr,
                         CDSNControl);

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

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

#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
                DoC_Command(this, NAND_CMD_PAGEPROG, 0);

                DoC_Command(this, NAND_CMD_STATUS, CDSN_CTRL_WP);
                /* There's an implicit DoC_WaitReady() in DoC_Command */

                if (DoC_is_Millennium(this)) {
                        ReadDOC(docptr, ReadPipeInit);
                        status = ReadDOC(docptr, LastDataRead);
                } else {
                        dummy = ReadDOC(docptr, CDSNSlowIO);
                        DoC_Delay(this, 2);
                        status = ReadDOC_(docptr, this->ioreg);
                }

                if (status & 1) {
                        printk(KERN_ERR "Error programming flash\n");
                        /* Error in programming */
                        *retlen = 0;
                        mutex_unlock(&this->lock);
                        return -EIO;
                }

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

                {
                        unsigned char x[8];
                        size_t dummy;
                        int ret;

                        /* Write the ECC data to flash */
                        for (di=0; di<6; di++)
                                x[di] = eccbuf[di];

                        x[6]=0x55;
                        x[7]=0x55;

                        ret = doc_write_oob_nolock(mtd, to, 8, &dummy, x);
                        if (ret) {
                                mutex_unlock(&this->lock);
                                return ret;
                        }
                }

                to += len;
                left -= len;
                buf += len;
        }

        mutex_unlock(&this->lock);
        return 0;
}

static int doc_read_oob(struct mtd_info *mtd, loff_t ofs,
                        struct mtd_oob_ops *ops)
{
        struct DiskOnChip *this = mtd->priv;
        int len256 = 0, ret;
        struct Nand *mychip;
        uint8_t *buf = ops->oobbuf;
        size_t len = ops->len;

        BUG_ON(ops->mode != MTD_OPS_PLACE_OOB);

        ofs += ops->ooboffs;

        mutex_lock(&this->lock);

        mychip = &this->chips[ofs >> this->chipshift];

        if (this->curfloor != mychip->floor) {
                DoC_SelectFloor(this, mychip->floor);
                DoC_SelectChip(this, mychip->chip);
        } else if (this->curchip != mychip->chip) {
                DoC_SelectChip(this, mychip->chip);
        }
        this->curfloor = mychip->floor;
        this->curchip = mychip->chip;

        /* update address for 2M x 8bit devices. OOB starts on the second */
        /* page to maintain compatibility with doc_read_ecc. */
        if (this->page256) {
                if (!(ofs & 0x8))
                        ofs += 0x100;
                else
                        ofs -= 0x8;
        }

        DoC_Command(this, NAND_CMD_READOOB, CDSN_CTRL_WP);
        DoC_Address(this, ADDR_COLUMN_PAGE, ofs, CDSN_CTRL_WP, 0);

        /* treat crossing 8-byte OOB data for 2M x 8bit devices */
        /* Note: datasheet says it should automaticaly wrap to the */
        /*       next OOB block, but it didn't work here. mf.      */
        if (this->page256 && ofs + len > (ofs | 0x7) + 1) {
                len256 = (ofs | 0x7) + 1 - ofs;
                DoC_ReadBuf(this, buf, len256);

                DoC_Command(this, NAND_CMD_READOOB, CDSN_CTRL_WP);
                DoC_Address(this, ADDR_COLUMN_PAGE, ofs & (~0x1ff),
                            CDSN_CTRL_WP, 0);
        }

        DoC_ReadBuf(this, &buf[len256], len - len256);

        ops->retlen = len;
        /* Reading the full OOB data drops us off of the end of the page,
         * causing the flash device to go into busy mode, so we need
         * to wait until ready 11.4.1 and Toshiba TC58256FT docs */

        ret = DoC_WaitReady(this);

        mutex_unlock(&this->lock);
        return ret;

}

static int doc_write_oob_nolock(struct mtd_info *mtd, loff_t ofs, size_t len,
                                size_t * retlen, const u_char * buf)
{
        struct DiskOnChip *this = mtd->priv;
        int len256 = 0;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip = &this->chips[ofs >> this->chipshift];
        volatile int dummy;
        int status;

        //      printk("doc_write_oob(%lx, %d): %2.2X %2.2X %2.2X %2.2X ... %2.2X %2.2X .. %2.2X %2.2X\n",(long)ofs, len,
        //   buf[0], buf[1], buf[2], buf[3], buf[8], buf[9], buf[14],buf[15]);

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

        /* issue the Read2 command to set the pointer to the Spare Data Area. */
        DoC_Command(this, NAND_CMD_READOOB, CDSN_CTRL_WP);

        /* update address for 2M x 8bit devices. OOB starts on the second */
        /* page to maintain compatibility with doc_read_ecc. */
        if (this->page256) {
                if (!(ofs & 0x8))
                        ofs += 0x100;
                else
                        ofs -= 0x8;
        }

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

        /* treat crossing 8-byte OOB data for 2M x 8bit devices */
        /* Note: datasheet says it should automaticaly wrap to the */
        /*       next OOB block, but it didn't work here. mf.      */
        if (this->page256 && ofs + len > (ofs | 0x7) + 1) {
                len256 = (ofs | 0x7) + 1 - ofs;
                DoC_WriteBuf(this, buf, len256);

                DoC_Command(this, NAND_CMD_PAGEPROG, 0);
                DoC_Command(this, NAND_CMD_STATUS, 0);
                /* DoC_WaitReady() is implicit in DoC_Command */

                if (DoC_is_Millennium(this)) {
                        ReadDOC(docptr, ReadPipeInit);
                        status = ReadDOC(docptr, LastDataRead);
                } else {
                        dummy = ReadDOC(docptr, CDSNSlowIO);
                        DoC_Delay(this, 2);
                        status = ReadDOC_(docptr, this->ioreg);
                }

                if (status & 1) {
                        printk(KERN_ERR "Error programming oob data\n");
                        /* There was an error */
                        *retlen = 0;
                        return -EIO;
                }
                DoC_Command(this, NAND_CMD_SEQIN, 0);
                DoC_Address(this, ADDR_COLUMN_PAGE, ofs & (~0x1ff), 0, 0);
        }

        DoC_WriteBuf(this, &buf[len256], len - len256);

        DoC_Command(this, NAND_CMD_PAGEPROG, 0);
        DoC_Command(this, NAND_CMD_STATUS, 0);
        /* DoC_WaitReady() is implicit in DoC_Command */

        if (DoC_is_Millennium(this)) {
                ReadDOC(docptr, ReadPipeInit);
                status = ReadDOC(docptr, LastDataRead);
        } else {
                dummy = ReadDOC(docptr, CDSNSlowIO);
                DoC_Delay(this, 2);
                status = ReadDOC_(docptr, this->ioreg);
        }

        if (status & 1) {
                printk(KERN_ERR "Error programming oob data\n");
                /* There was an error */
                *retlen = 0;
                return -EIO;
        }

        *retlen = len;
        return 0;

}

static int doc_write_oob(struct mtd_info *mtd, loff_t ofs,
                         struct mtd_oob_ops *ops)
{
        struct DiskOnChip *this = mtd->priv;
        int ret;

        BUG_ON(ops->mode != MTD_OPS_PLACE_OOB);

        mutex_lock(&this->lock);
        ret = doc_write_oob_nolock(mtd, ofs + ops->ooboffs, ops->len,
                                   &ops->retlen, ops->oobbuf);

        mutex_unlock(&this->lock);
        return ret;
}

static int doc_erase(struct mtd_info *mtd, struct erase_info *instr)
{
        struct DiskOnChip *this = mtd->priv;
        __u32 ofs = instr->addr;
        __u32 len = instr->len;
        volatile int dummy;
        void __iomem *docptr = this->virtadr;
        struct Nand *mychip;
        int status;

        mutex_lock(&this->lock);

        if (ofs & (mtd->erasesize-1) || len & (mtd->erasesize-1)) {
                mutex_unlock(&this->lock);
                return -EINVAL;
        }

        instr->state = MTD_ERASING;

        /* FIXME: Do this in the background. Use timers or schedule_task() */
        while(len) {
                mychip = &this->chips[ofs >> this->chipshift];

                if (this->curfloor != mychip->floor) {
                        DoC_SelectFloor(this, mychip->floor);
                        DoC_SelectChip(this, mychip->chip);
                } else if (this->curchip != mychip->chip) {
                        DoC_SelectChip(this, mychip->chip);
                }
                this->curfloor = mychip->floor;
                this->curchip = mychip->chip;

                DoC_Command(this, NAND_CMD_ERASE1, 0);
                DoC_Address(this, ADDR_PAGE, ofs, 0, 0);
                DoC_Command(this, NAND_CMD_ERASE2, 0);

                DoC_Command(this, NAND_CMD_STATUS, CDSN_CTRL_WP);

                if (DoC_is_Millennium(this)) {
                        ReadDOC(docptr, ReadPipeInit);
                        status = ReadDOC(docptr, LastDataRead);
                } else {
                        dummy = ReadDOC(docptr, CDSNSlowIO);
                        DoC_Delay(this, 2);
                        status = ReadDOC_(docptr, this->ioreg);
                }

                if (status & 1) {
                        printk(KERN_ERR "Error erasing at 0x%x\n", ofs);
                        /* There was an error */
                        instr->state = MTD_ERASE_FAILED;
                        goto callback;
                }
                ofs += mtd->erasesize;
                len -= mtd->erasesize;
        }
        instr->state = MTD_ERASE_DONE;

 callback:
        mtd_erase_callback(instr);

        mutex_unlock(&this->lock);
        return 0;
}


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

static void __exit cleanup_doc2000(void)
{
        struct mtd_info *mtd;
        struct DiskOnChip *this;

        while ((mtd = doc2klist)) {
                this = mtd->priv;
                doc2klist = this->nextdoc;

                mtd_device_unregister(mtd);

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

module_exit(cleanup_doc2000);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org> et al.");
MODULE_DESCRIPTION("MTD driver for DiskOnChip 2000 and Millennium");