nand/raw/diskonchip.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * (C) 2003 Red Hat, Inc.
 * (C) 2004 Dan Brown <dan_brown@ieee.org>
 * (C) 2004 Kalev Lember <kalev@smartlink.ee>
 *
 * Author: David Woodhouse <dwmw2@infradead.org>
 * Additional Diskonchip 2000 and Millennium support by Dan Brown <dan_brown@ieee.org>
 * Diskonchip Millennium Plus support by Kalev Lember <kalev@smartlink.ee>
 *
 * Error correction code lifted from the old docecc code
 * Author: Fabrice Bellard (fabrice.bellard@netgem.com)
 * Copyright (C) 2000 Netgem S.A.
 * converted to the generic Reed-Solomon library by Thomas Gleixner <tglx@linutronix.de>
 *
 * Interface to generic NAND code for M-Systems DiskOnChip devices
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/rslib.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/io.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.h>
#include <linux/mtd/doc2000.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/inftl.h>
#include <linux/module.h>

/* Where to look for the devices? */
#ifndef CONFIG_MTD_NAND_DISKONCHIP_PROBE_ADDRESS
#define CONFIG_MTD_NAND_DISKONCHIP_PROBE_ADDRESS 0
#endif

static unsigned long doc_locations[] __initdata = {
#if defined (__alpha__) || defined(__i386__) || defined(__x86_64__)
#ifdef CONFIG_MTD_NAND_DISKONCHIP_PROBE_HIGH
	0xfffc8000, 0xfffca000, 0xfffcc000, 0xfffce000,
	0xfffd0000, 0xfffd2000, 0xfffd4000, 0xfffd6000,
	0xfffd8000, 0xfffda000, 0xfffdc000, 0xfffde000,
	0xfffe0000, 0xfffe2000, 0xfffe4000, 0xfffe6000,
	0xfffe8000, 0xfffea000, 0xfffec000, 0xfffee000,
#else
	0xc8000, 0xca000, 0xcc000, 0xce000,
	0xd0000, 0xd2000, 0xd4000, 0xd6000,
	0xd8000, 0xda000, 0xdc000, 0xde000,
	0xe0000, 0xe2000, 0xe4000, 0xe6000,
	0xe8000, 0xea000, 0xec000, 0xee000,
#endif
#endif
	0xffffffff };

static struct mtd_info *doclist = NULL;

struct doc_priv {
	struct nand_controller base;
	void __iomem *virtadr;
	unsigned long physadr;
	u_char ChipID;
	u_char CDSNControl;
	int chips_per_floor;	/* The number of chips detected on each floor */
	int curfloor;
	int curchip;
	int mh0_page;
	int mh1_page;
	struct rs_control *rs_decoder;
	struct mtd_info *nextdoc;
	bool supports_32b_reads;

	/* Handle the last stage of initialization (BBT scan, partitioning) */
	int (*late_init)(struct mtd_info *mtd);
};

/* This is the ecc value computed by the HW ecc generator upon writing an empty
   page, one with all 0xff for data. */
static u_char empty_write_ecc[6] = { 0x4b, 0x00, 0xe2, 0x0e, 0x93, 0xf7 };

#define INFTL_BBT_RESERVED_BLOCKS 4

#define DoC_is_MillenniumPlus(doc) ((doc)->ChipID == DOC_ChipID_DocMilPlus16 || (doc)->ChipID == DOC_ChipID_DocMilPlus32)
#define DoC_is_Millennium(doc) ((doc)->ChipID == DOC_ChipID_DocMil)
#define DoC_is_2000(doc) ((doc)->ChipID == DOC_ChipID_Doc2k)

static int debug = 0;
module_param(debug, int, 0);

static int try_dword = 1;
module_param(try_dword, int, 0);

static int no_ecc_failures = 0;
module_param(no_ecc_failures, int, 0);

static int no_autopart = 0;
module_param(no_autopart, int, 0);

static int show_firmware_partition = 0;
module_param(show_firmware_partition, int, 0);

#ifdef CONFIG_MTD_NAND_DISKONCHIP_BBTWRITE
static int inftl_bbt_write = 1;
#else
static int inftl_bbt_write = 0;
#endif
module_param(inftl_bbt_write, int, 0);

static unsigned long doc_config_location = CONFIG_MTD_NAND_DISKONCHIP_PROBE_ADDRESS;
module_param(doc_config_location, ulong, 0);
MODULE_PARM_DESC(doc_config_location, "Physical memory address at which to probe for DiskOnChip");

/* Sector size for HW ECC */
#define SECTOR_SIZE 512
/* The sector bytes are packed into NB_DATA 10 bit words */
#define NB_DATA (((SECTOR_SIZE + 1) * 8 + 6) / 10)
/* Number of roots */
#define NROOTS 4
/* First consective root */
#define FCR 510
/* Number of symbols */
#define NN 1023

/*
 * The HW decoder in the DoC ASIC's provides us a error syndrome,
 * which we must convert to a standard syndrome usable by the generic
 * Reed-Solomon library code.
 *
 * Fabrice Bellard figured this out in the old docecc code. I added
 * some comments, improved a minor bit and converted it to make use
 * of the generic Reed-Solomon library. tglx
 */
static int doc_ecc_decode(struct rs_control *rs, uint8_t *data, uint8_t *ecc)
{
	int i, j, nerr, errpos[8];
	uint8_t parity;
	uint16_t ds[4], s[5], tmp, errval[8], syn[4];
	struct rs_codec *cd = rs->codec;

	memset(syn, 0, sizeof(syn));
	/* Convert the ecc bytes into words */
	ds[0] = ((ecc[4] & 0xff) >> 0) | ((ecc[5] & 0x03) << 8);
	ds[1] = ((ecc[5] & 0xfc) >> 2) | ((ecc[2] & 0x0f) << 6);
	ds[2] = ((ecc[2] & 0xf0) >> 4) | ((ecc[3] & 0x3f) << 4);
	ds[3] = ((ecc[3] & 0xc0) >> 6) | ((ecc[0] & 0xff) << 2);
	parity = ecc[1];

	/* Initialize the syndrome buffer */
	for (i = 0; i < NROOTS; i++)
		s[i] = ds[0];
	/*
	 *  Evaluate
	 *  s[i] = ds[3]x^3 + ds[2]x^2 + ds[1]x^1 + ds[0]
	 *  where x = alpha^(FCR + i)
	 */
	for (j = 1; j < NROOTS; j++) {
		if (ds[j] == 0)
			continue;
		tmp = cd->index_of[ds[j]];
		for (i = 0; i < NROOTS; i++)
			s[i] ^= cd->alpha_to[rs_modnn(cd, tmp + (FCR + i) * j)];
	}

	/* Calc syn[i] = s[i] / alpha^(v + i) */
	for (i = 0; i < NROOTS; i++) {
		if (s[i])
			syn[i] = rs_modnn(cd, cd->index_of[s[i]] + (NN - FCR - i));
	}
	/* Call the decoder library */
	nerr = decode_rs16(rs, NULL, NULL, 1019, syn, 0, errpos, 0, errval);

	/* Incorrectable errors ? */
	if (nerr < 0)
		return nerr;

	/*
	 * Correct the errors. The bitpositions are a bit of magic,
	 * but they are given by the design of the de/encoder circuit
	 * in the DoC ASIC's.
	 */
	for (i = 0; i < nerr; i++) {
		int index, bitpos, pos = 1015 - errpos[i];
		uint8_t val;
		if (pos >= NB_DATA && pos < 1019)
			continue;
		if (pos < NB_DATA) {
			/* extract bit position (MSB first) */
			pos = 10 * (NB_DATA - 1 - pos) - 6;
			/* now correct the following 10 bits. At most two bytes
			   can be modified since pos is even */
			index = (pos >> 3) ^ 1;
			bitpos = pos & 7;
			if ((index >= 0 && index < SECTOR_SIZE) || index == (SECTOR_SIZE + 1)) {
				val = (uint8_t) (errval[i] >> (2 + bitpos));
				parity ^= val;
				if (index < SECTOR_SIZE)
					data[index] ^= val;
			}
			index = ((pos >> 3) + 1) ^ 1;
			bitpos = (bitpos + 10) & 7;
			if (bitpos == 0)
				bitpos = 8;
			if ((index >= 0 && index < SECTOR_SIZE) || index == (SECTOR_SIZE + 1)) {
				val = (uint8_t) (errval[i] << (8 - bitpos));
				parity ^= val;
				if (index < SECTOR_SIZE)
					data[index] ^= val;
			}
		}
	}
	/* If the parity is wrong, no rescue possible */
	return parity ? -EBADMSG : nerr;
}

static void DoC_Delay(struct doc_priv *doc, unsigned short cycles)
{
	volatile char __always_unused dummy;
	int i;

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

}

#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(struct doc_priv *doc)
{
	void __iomem *docptr = doc->virtadr;
	unsigned long timeo = jiffies + (HZ * 10);

	if (debug)
		printk("_DoC_WaitReady...\n");
	/* Out-of-line routine to wait for chip response */
	if (DoC_is_MillenniumPlus(doc)) {
		while ((ReadDOC(docptr, Mplus_FlashControl) & CDSN_CTRL_FR_B_MASK) != CDSN_CTRL_FR_B_MASK) {
			if (time_after(jiffies, timeo)) {
				printk("_DoC_WaitReady timed out.\n");
				return -EIO;
			}
			udelay(1);
			cond_resched();
		}
	} else {
		while (!(ReadDOC(docptr, CDSNControl) & CDSN_CTRL_FR_B)) {
			if (time_after(jiffies, timeo)) {
				printk("_DoC_WaitReady timed out.\n");
				return -EIO;
			}
			udelay(1);
			cond_resched();
		}
	}

	return 0;
}

static inline int DoC_WaitReady(struct doc_priv *doc)
{
	void __iomem *docptr = doc->virtadr;
	int ret = 0;

	if (DoC_is_MillenniumPlus(doc)) {
		DoC_Delay(doc, 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(doc);
	} else {
		DoC_Delay(doc, 4);

		if (!(ReadDOC(docptr, CDSNControl) & CDSN_CTRL_FR_B))
			/* Call the out-of-line routine to wait */
			ret = _DoC_WaitReady(doc);
		DoC_Delay(doc, 2);
	}

	if (debug)
		printk("DoC_WaitReady OK\n");
	return ret;
}

static void doc2000_write_byte(struct nand_chip *this, u_char datum)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;

	if (debug)
		printk("write_byte %02x\n", datum);
	WriteDOC(datum, docptr, CDSNSlowIO);
	WriteDOC(datum, docptr, 2k_CDSN_IO);
}

static void doc2000_writebuf(struct nand_chip *this, const u_char *buf,
			     int len)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	int i;
	if (debug)
		printk("writebuf of %d bytes: ", len);
	for (i = 0; i < len; i++) {
		WriteDOC_(buf[i], docptr, DoC_2k_CDSN_IO + i);
		if (debug && i < 16)
			printk("%02x ", buf[i]);
	}
	if (debug)
		printk("\n");
}

static void doc2000_readbuf(struct nand_chip *this, u_char *buf, int len)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	u32 *buf32 = (u32 *)buf;
	int i;

	if (debug)
		printk("readbuf of %d bytes: ", len);

	if (!doc->supports_32b_reads ||
	    ((((unsigned long)buf) | len) & 3)) {
		for (i = 0; i < len; i++)
			buf[i] = ReadDOC(docptr, 2k_CDSN_IO + i);
	} else {
		for (i = 0; i < len / 4; i++)
			buf32[i] = readl(docptr + DoC_2k_CDSN_IO + i);
	}
}

/*
 * We need our own readid() here because it's called before the NAND chip
 * has been initialized, and calling nand_op_readid() would lead to a NULL
 * pointer exception when dereferencing the NAND timings.
 */
static void doc200x_readid(struct nand_chip *this, unsigned int cs, u8 *id)
{
	u8 addr = 0;
	struct nand_op_instr instrs[] = {
		NAND_OP_CMD(NAND_CMD_READID, 0),
		NAND_OP_ADDR(1, &addr, 50),
		NAND_OP_8BIT_DATA_IN(2, id, 0),
	};

	struct nand_operation op = NAND_OPERATION(cs, instrs);

	if (!id)
		op.ninstrs--;

	this->controller->ops->exec_op(this, &op, false);
}

static uint16_t __init doc200x_ident_chip(struct mtd_info *mtd, int nr)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);
	uint16_t ret;
	u8 id[2];

	doc200x_readid(this, nr, id);

	ret = ((u16)id[0] << 8) | id[1];

	if (doc->ChipID == DOC_ChipID_Doc2k && try_dword && !nr) {
		/* First chip probe. See if we get same results by 32-bit access */
		union {
			uint32_t dword;
			uint8_t byte[4];
		} ident;
		void __iomem *docptr = doc->virtadr;

		doc200x_readid(this, nr, NULL);

		ident.dword = readl(docptr + DoC_2k_CDSN_IO);
		if (((ident.byte[0] << 8) | ident.byte[1]) == ret) {
			pr_info("DiskOnChip 2000 responds to DWORD access\n");
			doc->supports_32b_reads = true;
		}
	}

	return ret;
}

static void __init doc2000_count_chips(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);
	uint16_t mfrid;
	int i;

	/* Max 4 chips per floor on DiskOnChip 2000 */
	doc->chips_per_floor = 4;

	/* Find out what the first chip is */
	mfrid = doc200x_ident_chip(mtd, 0);

	/* Find how many chips in each floor. */
	for (i = 1; i < 4; i++) {
		if (doc200x_ident_chip(mtd, i) != mfrid)
			break;
	}
	doc->chips_per_floor = i;
	pr_debug("Detected %d chips per floor.\n", i);
}

static void doc2001_write_byte(struct nand_chip *this, u_char datum)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;

	WriteDOC(datum, docptr, CDSNSlowIO);
	WriteDOC(datum, docptr, Mil_CDSN_IO);
	WriteDOC(datum, docptr, WritePipeTerm);
}

static void doc2001_writebuf(struct nand_chip *this, const u_char *buf, int len)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	int i;

	for (i = 0; i < len; i++)
		WriteDOC_(buf[i], docptr, DoC_Mil_CDSN_IO + i);
	/* Terminate write pipeline */
	WriteDOC(0x00, docptr, WritePipeTerm);
}

static void doc2001_readbuf(struct nand_chip *this, u_char *buf, int len)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	int i;

	/* Start read pipeline */
	ReadDOC(docptr, ReadPipeInit);

	for (i = 0; i < len - 1; i++)
		buf[i] = ReadDOC(docptr, Mil_CDSN_IO + (i & 0xff));

	/* Terminate read pipeline */
	buf[i] = ReadDOC(docptr, LastDataRead);
}

static void doc2001plus_writebuf(struct nand_chip *this, const u_char *buf, int len)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	int i;

	if (debug)
		printk("writebuf of %d bytes: ", len);
	for (i = 0; i < len; i++) {
		WriteDOC_(buf[i], docptr, DoC_Mil_CDSN_IO + i);
		if (debug && i < 16)
			printk("%02x ", buf[i]);
	}
	if (debug)
		printk("\n");
}

static void doc2001plus_readbuf(struct nand_chip *this, u_char *buf, int len)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	int i;

	if (debug)
		printk("readbuf of %d bytes: ", len);

	/* Start read pipeline */
	ReadDOC(docptr, Mplus_ReadPipeInit);
	ReadDOC(docptr, Mplus_ReadPipeInit);

	for (i = 0; i < len - 2; i++) {
		buf[i] = ReadDOC(docptr, Mil_CDSN_IO);
		if (debug && i < 16)
			printk("%02x ", buf[i]);
	}

	/* Terminate read pipeline */
	if (len >= 2) {
		buf[len - 2] = ReadDOC(docptr, Mplus_LastDataRead);
		if (debug && i < 16)
			printk("%02x ", buf[len - 2]);
	}

	buf[len - 1] = ReadDOC(docptr, Mplus_LastDataRead);
	if (debug && i < 16)
		printk("%02x ", buf[len - 1]);
	if (debug)
		printk("\n");
}

static void doc200x_write_control(struct doc_priv *doc, u8 value)
{
	WriteDOC(value, doc->virtadr, CDSNControl);
	/* 11.4.3 -- 4 NOPs after CSDNControl write */
	DoC_Delay(doc, 4);
}

static void doc200x_exec_instr(struct nand_chip *this,
			       const struct nand_op_instr *instr)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	unsigned int i;

	switch (instr->type) {
	case NAND_OP_CMD_INSTR:
		doc200x_write_control(doc, CDSN_CTRL_CE | CDSN_CTRL_CLE);
		doc2000_write_byte(this, instr->ctx.cmd.opcode);
		break;

	case NAND_OP_ADDR_INSTR:
		doc200x_write_control(doc, CDSN_CTRL_CE | CDSN_CTRL_ALE);
		for (i = 0; i < instr->ctx.addr.naddrs; i++) {
			u8 addr = instr->ctx.addr.addrs[i];

			if (DoC_is_2000(doc))
				doc2000_write_byte(this, addr);
			else
				doc2001_write_byte(this, addr);
		}
		break;

	case NAND_OP_DATA_IN_INSTR:
		doc200x_write_control(doc, CDSN_CTRL_CE);
		if (DoC_is_2000(doc))
			doc2000_readbuf(this, instr->ctx.data.buf.in,
					instr->ctx.data.len);
		else
			doc2001_readbuf(this, instr->ctx.data.buf.in,
					instr->ctx.data.len);
		break;

	case NAND_OP_DATA_OUT_INSTR:
		doc200x_write_control(doc, CDSN_CTRL_CE);
		if (DoC_is_2000(doc))
			doc2000_writebuf(this, instr->ctx.data.buf.out,
					 instr->ctx.data.len);
		else
			doc2001_writebuf(this, instr->ctx.data.buf.out,
					 instr->ctx.data.len);
		break;

	case NAND_OP_WAITRDY_INSTR:
		DoC_WaitReady(doc);
		break;
	}

	if (instr->delay_ns)
		ndelay(instr->delay_ns);
}

static int doc200x_exec_op(struct nand_chip *this,
			   const struct nand_operation *op,
			   bool check_only)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	unsigned int i;

	if (check_only)
		return true;

	doc->curchip = op->cs % doc->chips_per_floor;
	doc->curfloor = op->cs / doc->chips_per_floor;

	WriteDOC(doc->curfloor, doc->virtadr, FloorSelect);
	WriteDOC(doc->curchip, doc->virtadr, CDSNDeviceSelect);

	/* Assert CE pin */
	doc200x_write_control(doc, CDSN_CTRL_CE);

	for (i = 0; i < op->ninstrs; i++)
		doc200x_exec_instr(this, &op->instrs[i]);

	/* De-assert CE pin */
	doc200x_write_control(doc, 0);

	return 0;
}

static void doc2001plus_write_pipe_term(struct doc_priv *doc)
{
	WriteDOC(0x00, doc->virtadr, Mplus_WritePipeTerm);
	WriteDOC(0x00, doc->virtadr, Mplus_WritePipeTerm);
}

static void doc2001plus_exec_instr(struct nand_chip *this,
				   const struct nand_op_instr *instr)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	unsigned int i;

	switch (instr->type) {
	case NAND_OP_CMD_INSTR:
		WriteDOC(instr->ctx.cmd.opcode, doc->virtadr, Mplus_FlashCmd);
		doc2001plus_write_pipe_term(doc);
		break;

	case NAND_OP_ADDR_INSTR:
		for (i = 0; i < instr->ctx.addr.naddrs; i++) {
			u8 addr = instr->ctx.addr.addrs[i];

			WriteDOC(addr, doc->virtadr, Mplus_FlashAddress);
		}
		doc2001plus_write_pipe_term(doc);
		/* deassert ALE */
		WriteDOC(0, doc->virtadr, Mplus_FlashControl);
		break;

	case NAND_OP_DATA_IN_INSTR:
		doc2001plus_readbuf(this, instr->ctx.data.buf.in,
				    instr->ctx.data.len);
		break;
	case NAND_OP_DATA_OUT_INSTR:
		doc2001plus_writebuf(this, instr->ctx.data.buf.out,
				     instr->ctx.data.len);
		doc2001plus_write_pipe_term(doc);
		break;
	case NAND_OP_WAITRDY_INSTR:
		DoC_WaitReady(doc);
		break;
	}

	if (instr->delay_ns)
		ndelay(instr->delay_ns);
}

static int doc2001plus_exec_op(struct nand_chip *this,
			       const struct nand_operation *op,
			       bool check_only)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	unsigned int i;

	if (check_only)
		return true;

	doc->curchip = op->cs % doc->chips_per_floor;
	doc->curfloor = op->cs / doc->chips_per_floor;

	/* Assert ChipEnable and deassert WriteProtect */
	WriteDOC(DOC_FLASH_CE, doc->virtadr, Mplus_FlashSelect);

	for (i = 0; i < op->ninstrs; i++)
		doc2001plus_exec_instr(this, &op->instrs[i]);

	/* De-assert ChipEnable */
	WriteDOC(0, doc->virtadr, Mplus_FlashSelect);

	return 0;
}

static void doc200x_enable_hwecc(struct nand_chip *this, int mode)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;

	/* Prime the ECC engine */
	switch (mode) {
	case NAND_ECC_READ:
		WriteDOC(DOC_ECC_RESET, docptr, ECCConf);
		WriteDOC(DOC_ECC_EN, docptr, ECCConf);
		break;
	case NAND_ECC_WRITE:
		WriteDOC(DOC_ECC_RESET, docptr, ECCConf);
		WriteDOC(DOC_ECC_EN | DOC_ECC_RW, docptr, ECCConf);
		break;
	}
}

static void doc2001plus_enable_hwecc(struct nand_chip *this, int mode)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;

	/* Prime the ECC engine */
	switch (mode) {
	case NAND_ECC_READ:
		WriteDOC(DOC_ECC_RESET, docptr, Mplus_ECCConf);
		WriteDOC(DOC_ECC_EN, docptr, Mplus_ECCConf);
		break;
	case NAND_ECC_WRITE:
		WriteDOC(DOC_ECC_RESET, docptr, Mplus_ECCConf);
		WriteDOC(DOC_ECC_EN | DOC_ECC_RW, docptr, Mplus_ECCConf);
		break;
	}
}

/* This code is only called on write */
static int doc200x_calculate_ecc(struct nand_chip *this, const u_char *dat,
				 unsigned char *ecc_code)
{
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	int i;
	int __always_unused emptymatch = 1;

	/* flush the pipeline */
	if (DoC_is_2000(doc)) {
		WriteDOC(doc->CDSNControl & ~CDSN_CTRL_FLASH_IO, docptr, CDSNControl);
		WriteDOC(0, docptr, 2k_CDSN_IO);
		WriteDOC(0, docptr, 2k_CDSN_IO);
		WriteDOC(0, docptr, 2k_CDSN_IO);
		WriteDOC(doc->CDSNControl, docptr, CDSNControl);
	} else if (DoC_is_MillenniumPlus(doc)) {
		WriteDOC(0, docptr, Mplus_NOP);
		WriteDOC(0, docptr, Mplus_NOP);
		WriteDOC(0, docptr, Mplus_NOP);
	} else {
		WriteDOC(0, docptr, NOP);
		WriteDOC(0, docptr, NOP);
		WriteDOC(0, docptr, NOP);
	}

	for (i = 0; i < 6; i++) {
		if (DoC_is_MillenniumPlus(doc))
			ecc_code[i] = ReadDOC_(docptr, DoC_Mplus_ECCSyndrome0 + i);
		else
			ecc_code[i] = ReadDOC_(docptr, DoC_ECCSyndrome0 + i);
		if (ecc_code[i] != empty_write_ecc[i])
			emptymatch = 0;
	}
	if (DoC_is_MillenniumPlus(doc))
		WriteDOC(DOC_ECC_DIS, docptr, Mplus_ECCConf);
	else
		WriteDOC(DOC_ECC_DIS, docptr, ECCConf);
#if 0
	/* If emptymatch=1, we might have an all-0xff data buffer.  Check. */
	if (emptymatch) {
		/* Note: this somewhat expensive test should not be triggered
		   often.  It could be optimized away by examining the data in
		   the writebuf routine, and remembering the result. */
		for (i = 0; i < 512; i++) {
			if (dat[i] == 0xff)
				continue;
			emptymatch = 0;
			break;
		}
	}
	/* If emptymatch still =1, we do have an all-0xff data buffer.
	   Return all-0xff ecc value instead of the computed one, so
	   it'll look just like a freshly-erased page. */
	if (emptymatch)
		memset(ecc_code, 0xff, 6);
#endif
	return 0;
}

static int doc200x_correct_data(struct nand_chip *this, u_char *dat,
				u_char *read_ecc, u_char *isnull)
{
	int i, ret = 0;
	struct doc_priv *doc = nand_get_controller_data(this);
	void __iomem *docptr = doc->virtadr;
	uint8_t calc_ecc[6];
	volatile u_char dummy;

	/* flush the pipeline */
	if (DoC_is_2000(doc)) {
		dummy = ReadDOC(docptr, 2k_ECCStatus);
		dummy = ReadDOC(docptr, 2k_ECCStatus);
		dummy = ReadDOC(docptr, 2k_ECCStatus);
	} else if (DoC_is_MillenniumPlus(doc)) {
		dummy = ReadDOC(docptr, Mplus_ECCConf);
		dummy = ReadDOC(docptr, Mplus_ECCConf);
		dummy = ReadDOC(docptr, Mplus_ECCConf);
	} else {
		dummy = ReadDOC(docptr, ECCConf);
		dummy = ReadDOC(docptr, ECCConf);
		dummy = ReadDOC(docptr, ECCConf);
	}

	/* Error occurred ? */
	if (dummy & 0x80) {
		for (i = 0; i < 6; i++) {
			if (DoC_is_MillenniumPlus(doc))
				calc_ecc[i] = ReadDOC_(docptr, DoC_Mplus_ECCSyndrome0 + i);
			else
				calc_ecc[i] = ReadDOC_(docptr, DoC_ECCSyndrome0 + i);
		}

		ret = doc_ecc_decode(doc->rs_decoder, dat, calc_ecc);
		if (ret > 0)
			pr_err("doc200x_correct_data corrected %d errors\n",
			       ret);
	}
	if (DoC_is_MillenniumPlus(doc))
		WriteDOC(DOC_ECC_DIS, docptr, Mplus_ECCConf);
	else
		WriteDOC(DOC_ECC_DIS, docptr, ECCConf);
	if (no_ecc_failures && mtd_is_eccerr(ret)) {
		pr_err("suppressing ECC failure\n");
		ret = 0;
	}
	return ret;
}

//u_char mydatabuf[528];

static int doc200x_ooblayout_ecc(struct mtd_info *mtd, int section,
				 struct mtd_oob_region *oobregion)
{
	if (section)
		return -ERANGE;

	oobregion->offset = 0;
	oobregion->length = 6;

	return 0;
}

static int doc200x_ooblayout_free(struct mtd_info *mtd, int section,
				  struct mtd_oob_region *oobregion)
{
	if (section > 1)
		return -ERANGE;

	/*
	 * The strange out-of-order free bytes definition is a (possibly
	 * unneeded) attempt to retain compatibility.  It used to read:
	 *	.oobfree = { {8, 8} }
	 * Since that leaves two bytes unusable, it was changed.  But the
	 * following scheme might affect existing jffs2 installs by moving the
	 * cleanmarker:
	 *	.oobfree = { {6, 10} }
	 * jffs2 seems to handle the above gracefully, but the current scheme
	 * seems safer. The only problem with it is that any code retrieving
	 * free bytes position must be able to handle out-of-order segments.
	 */
	if (!section) {
		oobregion->offset = 8;
		oobregion->length = 8;
	} else {
		oobregion->offset = 6;
		oobregion->length = 2;
	}

	return 0;
}

static const struct mtd_ooblayout_ops doc200x_ooblayout_ops = {
	.ecc = doc200x_ooblayout_ecc,
	.free = doc200x_ooblayout_free,
};

/* Find the (I)NFTL Media Header, and optionally also the mirror media header.
   On successful return, buf will contain a copy of the media header for
   further processing.  id is the string to scan for, and will presumably be
   either "ANAND" or "BNAND".  If findmirror=1, also look for the mirror media
   header.  The page #s of the found media headers are placed in mh0_page and
   mh1_page in the DOC private structure. */
static int __init find_media_headers(struct mtd_info *mtd, u_char *buf, const char *id, int findmirror)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);
	unsigned offs;
	int ret;
	size_t retlen;

	for (offs = 0; offs < mtd->size; offs += mtd->erasesize) {
		ret = mtd_read(mtd, offs, mtd->writesize, &retlen, buf);
		if (retlen != mtd->writesize)
			continue;
		if (ret) {
			pr_warn("ECC error scanning DOC at 0x%x\n", offs);
		}
		if (memcmp(buf, id, 6))
			continue;
		pr_info("Found DiskOnChip %s Media Header at 0x%x\n", id, offs);
		if (doc->mh0_page == -1) {
			doc->mh0_page = offs >> this->page_shift;
			if (!findmirror)
				return 1;
			continue;
		}
		doc->mh1_page = offs >> this->page_shift;
		return 2;
	}
	if (doc->mh0_page == -1) {
		pr_warn("DiskOnChip %s Media Header not found.\n", id);
		return 0;
	}
	/* Only one mediaheader was found.  We want buf to contain a
	   mediaheader on return, so we'll have to re-read the one we found. */
	offs = doc->mh0_page << this->page_shift;
	ret = mtd_read(mtd, offs, mtd->writesize, &retlen, buf);
	if (retlen != mtd->writesize) {
		/* Insanity.  Give up. */
		pr_err("Read DiskOnChip Media Header once, but can't reread it???\n");
		return 0;
	}
	return 1;
}

static inline int __init nftl_partscan(struct mtd_info *mtd, struct mtd_partition *parts)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);
	struct nand_memory_organization *memorg;
	int ret = 0;
	u_char *buf;
	struct NFTLMediaHeader *mh;
	const unsigned psize = 1 << this->page_shift;
	int numparts = 0;
	unsigned blocks, maxblocks;
	int offs, numheaders;

	memorg = nanddev_get_memorg(&this->base);

	buf = kmalloc(mtd->writesize, GFP_KERNEL);
	if (!buf) {
		return 0;
	}
	if (!(numheaders = find_media_headers(mtd, buf, "ANAND", 1)))
		goto out;
	mh = (struct NFTLMediaHeader *)buf;

	le16_to_cpus(&mh->NumEraseUnits);
	le16_to_cpus(&mh->FirstPhysicalEUN);
	le32_to_cpus(&mh->FormattedSize);

	pr_info("    DataOrgID        = %s\n"
		"    NumEraseUnits    = %d\n"
		"    FirstPhysicalEUN = %d\n"
		"    FormattedSize    = %d\n"
		"    UnitSizeFactor   = %d\n",
		mh->DataOrgID, mh->NumEraseUnits,
		mh->FirstPhysicalEUN, mh->FormattedSize,
		mh->UnitSizeFactor);

	blocks = mtd->size >> this->phys_erase_shift;
	maxblocks = min(32768U, mtd->erasesize - psize);

	if (mh->UnitSizeFactor == 0x00) {
		/* Auto-determine UnitSizeFactor.  The constraints are:
		   - There can be at most 32768 virtual blocks.
		   - There can be at most (virtual block size - page size)
		   virtual blocks (because MediaHeader+BBT must fit in 1).
		 */
		mh->UnitSizeFactor = 0xff;
		while (blocks > maxblocks) {
			blocks >>= 1;
			maxblocks = min(32768U, (maxblocks << 1) + psize);
			mh->UnitSizeFactor--;
		}
		pr_warn("UnitSizeFactor=0x00 detected.  Correct value is assumed to be 0x%02x.\n", mh->UnitSizeFactor);
	}

	/* NOTE: The lines below modify internal variables of the NAND and MTD
	   layers; variables with have already been configured by nand_scan.
	   Unfortunately, we didn't know before this point what these values
	   should be.  Thus, this code is somewhat dependent on the exact
	   implementation of the NAND layer.  */
	if (mh->UnitSizeFactor != 0xff) {
		this->bbt_erase_shift += (0xff - mh->UnitSizeFactor);
		memorg->pages_per_eraseblock <<= (0xff - mh->UnitSizeFactor);
		mtd->erasesize <<= (0xff - mh->UnitSizeFactor);
		pr_info("Setting virtual erase size to %d\n", mtd->erasesize);
		blocks = mtd->size >> this->bbt_erase_shift;
		maxblocks = min(32768U, mtd->erasesize - psize);
	}

	if (blocks > maxblocks) {
		pr_err("UnitSizeFactor of 0x%02x is inconsistent with device size.  Aborting.\n", mh->UnitSizeFactor);
		goto out;
	}

	/* Skip past the media headers. */
	offs = max(doc->mh0_page, doc->mh1_page);
	offs <<= this->page_shift;
	offs += mtd->erasesize;

	if (show_firmware_partition == 1) {
		parts[0].name = " DiskOnChip Firmware / Media Header partition";
		parts[0].offset = 0;
		parts[0].size = offs;
		numparts = 1;
	}

	parts[numparts].name = " DiskOnChip BDTL partition";
	parts[numparts].offset = offs;
	parts[numparts].size = (mh->NumEraseUnits - numheaders) << this->bbt_erase_shift;

	offs += parts[numparts].size;
	numparts++;

	if (offs < mtd->size) {
		parts[numparts].name = " DiskOnChip Remainder partition";
		parts[numparts].offset = offs;
		parts[numparts].size = mtd->size - offs;
		numparts++;
	}

	ret = numparts;
 out:
	kfree(buf);
	return ret;
}

/* This is a stripped-down copy of the code in inftlmount.c */
static inline int __init inftl_partscan(struct mtd_info *mtd, struct mtd_partition *parts)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);
	int ret = 0;
	u_char *buf;
	struct INFTLMediaHeader *mh;
	struct INFTLPartition *ip;
	int numparts = 0;
	int blocks;
	int vshift, lastvunit = 0;
	int i;
	int end = mtd->size;

	if (inftl_bbt_write)
		end -= (INFTL_BBT_RESERVED_BLOCKS << this->phys_erase_shift);

	buf = kmalloc(mtd->writesize, GFP_KERNEL);
	if (!buf) {
		return 0;
	}

	if (!find_media_headers(mtd, buf, "BNAND", 0))
		goto out;
	doc->mh1_page = doc->mh0_page + (4096 >> this->page_shift);
	mh = (struct INFTLMediaHeader *)buf;

	le32_to_cpus(&mh->NoOfBootImageBlocks);
	le32_to_cpus(&mh->NoOfBinaryPartitions);
	le32_to_cpus(&mh->NoOfBDTLPartitions);
	le32_to_cpus(&mh->BlockMultiplierBits);
	le32_to_cpus(&mh->FormatFlags);
	le32_to_cpus(&mh->PercentUsed);

	pr_info("    bootRecordID          = %s\n"
		"    NoOfBootImageBlocks   = %d\n"
		"    NoOfBinaryPartitions  = %d\n"
		"    NoOfBDTLPartitions    = %d\n"
		"    BlockMultiplierBits   = %d\n"
		"    FormatFlgs            = %d\n"
		"    OsakVersion           = %d.%d.%d.%d\n"
		"    PercentUsed           = %d\n",
		mh->bootRecordID, mh->NoOfBootImageBlocks,
		mh->NoOfBinaryPartitions,
		mh->NoOfBDTLPartitions,
		mh->BlockMultiplierBits, mh->FormatFlags,
		((unsigned char *) &mh->OsakVersion)[0] & 0xf,
		((unsigned char *) &mh->OsakVersion)[1] & 0xf,
		((unsigned char *) &mh->OsakVersion)[2] & 0xf,
		((unsigned char *) &mh->OsakVersion)[3] & 0xf,
		mh->PercentUsed);

	vshift = this->phys_erase_shift + mh->BlockMultiplierBits;

	blocks = mtd->size >> vshift;
	if (blocks > 32768) {
		pr_err("BlockMultiplierBits=%d is inconsistent with device size.  Aborting.\n", mh->BlockMultiplierBits);
		goto out;
	}

	blocks = doc->chips_per_floor << (this->chip_shift - this->phys_erase_shift);
	if (inftl_bbt_write && (blocks > mtd->erasesize)) {
		pr_err("Writeable BBTs spanning more than one erase block are not yet supported.  FIX ME!\n");
		goto out;
	}

	/* Scan the partitions */
	for (i = 0; (i < 4); i++) {
		ip = &(mh->Partitions[i]);
		le32_to_cpus(&ip->virtualUnits);
		le32_to_cpus(&ip->firstUnit);
		le32_to_cpus(&ip->lastUnit);
		le32_to_cpus(&ip->flags);
		le32_to_cpus(&ip->spareUnits);
		le32_to_cpus(&ip->Reserved0);

		pr_info("    PARTITION[%d] ->\n"
			"        virtualUnits    = %d\n"
			"        firstUnit       = %d\n"
			"        lastUnit        = %d\n"
			"        flags           = 0x%x\n"
			"        spareUnits      = %d\n",
			i, ip->virtualUnits, ip->firstUnit,
			ip->lastUnit, ip->flags,
			ip->spareUnits);

		if ((show_firmware_partition == 1) &&
		    (i == 0) && (ip->firstUnit > 0)) {
			parts[0].name = " DiskOnChip IPL / Media Header partition";
			parts[0].offset = 0;
			parts[0].size = mtd->erasesize * ip->firstUnit;
			numparts = 1;
		}

		if (ip->flags & INFTL_BINARY)
			parts[numparts].name = " DiskOnChip BDK partition";
		else
			parts[numparts].name = " DiskOnChip BDTL partition";
		parts[numparts].offset = ip->firstUnit << vshift;
		parts[numparts].size = (1 + ip->lastUnit - ip->firstUnit) << vshift;
		numparts++;
		if (ip->lastUnit > lastvunit)
			lastvunit = ip->lastUnit;
		if (ip->flags & INFTL_LAST)
			break;
	}
	lastvunit++;
	if ((lastvunit << vshift) < end) {
		parts[numparts].name = " DiskOnChip Remainder partition";
		parts[numparts].offset = lastvunit << vshift;
		parts[numparts].size = end - parts[numparts].offset;
		numparts++;
	}
	ret = numparts;
 out:
	kfree(buf);
	return ret;
}

static int __init nftl_scan_bbt(struct mtd_info *mtd)
{
	int ret, numparts;
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);
	struct mtd_partition parts[2];

	memset((char *)parts, 0, sizeof(parts));
	/* On NFTL, we have to find the media headers before we can read the
	   BBTs, since they're stored in the media header eraseblocks. */
	numparts = nftl_partscan(mtd, parts);
	if (!numparts)
		return -EIO;
	this->bbt_td->options = NAND_BBT_ABSPAGE | NAND_BBT_8BIT |
				NAND_BBT_SAVECONTENT | NAND_BBT_WRITE |
				NAND_BBT_VERSION;
	this->bbt_td->veroffs = 7;
	this->bbt_td->pages[0] = doc->mh0_page + 1;
	if (doc->mh1_page != -1) {
		this->bbt_md->options = NAND_BBT_ABSPAGE | NAND_BBT_8BIT |
					NAND_BBT_SAVECONTENT | NAND_BBT_WRITE |
					NAND_BBT_VERSION;
		this->bbt_md->veroffs = 7;
		this->bbt_md->pages[0] = doc->mh1_page + 1;
	} else {
		this->bbt_md = NULL;
	}

	ret = nand_create_bbt(this);
	if (ret)
		return ret;

	return mtd_device_register(mtd, parts, no_autopart ? 0 : numparts);
}

static int __init inftl_scan_bbt(struct mtd_info *mtd)
{
	int ret, numparts;
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);
	struct mtd_partition parts[5];

	if (nanddev_ntargets(&this->base) > doc->chips_per_floor) {
		pr_err("Multi-floor INFTL devices not yet supported.\n");
		return -EIO;
	}

	if (DoC_is_MillenniumPlus(doc)) {
		this->bbt_td->options = NAND_BBT_2BIT | NAND_BBT_ABSPAGE;
		if (inftl_bbt_write)
			this->bbt_td->options |= NAND_BBT_WRITE;
		this->bbt_td->pages[0] = 2;
		this->bbt_md = NULL;
	} else {
		this->bbt_td->options = NAND_BBT_LASTBLOCK | NAND_BBT_8BIT | NAND_BBT_VERSION;
		if (inftl_bbt_write)
			this->bbt_td->options |= NAND_BBT_WRITE;
		this->bbt_td->offs = 8;
		this->bbt_td->len = 8;
		this->bbt_td->veroffs = 7;
		this->bbt_td->maxblocks = INFTL_BBT_RESERVED_BLOCKS;
		this->bbt_td->reserved_block_code = 0x01;
		this->bbt_td->pattern = "MSYS_BBT";

		this->bbt_md->options = NAND_BBT_LASTBLOCK | NAND_BBT_8BIT | NAND_BBT_VERSION;
		if (inftl_bbt_write)
			this->bbt_md->options |= NAND_BBT_WRITE;
		this->bbt_md->offs = 8;
		this->bbt_md->len = 8;
		this->bbt_md->veroffs = 7;
		this->bbt_md->maxblocks = INFTL_BBT_RESERVED_BLOCKS;
		this->bbt_md->reserved_block_code = 0x01;
		this->bbt_md->pattern = "TBB_SYSM";
	}

	ret = nand_create_bbt(this);
	if (ret)
		return ret;

	memset((char *)parts, 0, sizeof(parts));
	numparts = inftl_partscan(mtd, parts);
	/* At least for now, require the INFTL Media Header.  We could probably
	   do without it for non-INFTL use, since all it gives us is
	   autopartitioning, but I want to give it more thought. */
	if (!numparts)
		return -EIO;
	return mtd_device_register(mtd, parts, no_autopart ? 0 : numparts);
}

static inline int __init doc2000_init(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);

	doc->late_init = nftl_scan_bbt;

	doc->CDSNControl = CDSN_CTRL_FLASH_IO | CDSN_CTRL_ECC_IO;
	doc2000_count_chips(mtd);
	mtd->name = "DiskOnChip 2000 (NFTL Model)";
	return (4 * doc->chips_per_floor);
}

static inline int __init doc2001_init(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);

	ReadDOC(doc->virtadr, ChipID);
	ReadDOC(doc->virtadr, ChipID);
	ReadDOC(doc->virtadr, ChipID);
	if (ReadDOC(doc->virtadr, ChipID) != DOC_ChipID_DocMil) {
		/* It's not a Millennium; it's one of the newer
		   DiskOnChip 2000 units with a similar ASIC.
		   Treat it like a Millennium, except that it
		   can have multiple chips. */
		doc2000_count_chips(mtd);
		mtd->name = "DiskOnChip 2000 (INFTL Model)";
		doc->late_init = inftl_scan_bbt;
		return (4 * doc->chips_per_floor);
	} else {
		/* Bog-standard Millennium */
		doc->chips_per_floor = 1;
		mtd->name = "DiskOnChip Millennium";
		doc->late_init = nftl_scan_bbt;
		return 1;
	}
}

static inline int __init doc2001plus_init(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd_to_nand(mtd);
	struct doc_priv *doc = nand_get_controller_data(this);

	doc->late_init = inftl_scan_bbt;
	this->ecc.hwctl = doc2001plus_enable_hwecc;

	doc->chips_per_floor = 1;
	mtd->name = "DiskOnChip Millennium Plus";

	return 1;
}

static int doc200x_attach_chip(struct nand_chip *chip)
{
	if (chip->ecc.engine_type != NAND_ECC_ENGINE_TYPE_ON_HOST)
		return 0;

	chip->ecc.placement = NAND_ECC_PLACEMENT_INTERLEAVED;
	chip->ecc.size = 512;
	chip->ecc.bytes = 6;
	chip->ecc.strength = 2;
	chip->ecc.options = NAND_ECC_GENERIC_ERASED_CHECK;
	chip->ecc.hwctl = doc200x_enable_hwecc;
	chip->ecc.calculate = doc200x_calculate_ecc;
	chip->ecc.correct = doc200x_correct_data;

	return 0;
}

static const struct nand_controller_ops doc200x_ops = {
	.exec_op = doc200x_exec_op,
	.attach_chip = doc200x_attach_chip,
};

static const struct nand_controller_ops doc2001plus_ops = {
	.exec_op = doc2001plus_exec_op,
	.attach_chip = doc200x_attach_chip,
};

static int __init doc_probe(unsigned long physadr)
{
	struct nand_chip *nand = NULL;
	struct doc_priv *doc = NULL;
	unsigned char ChipID;
	struct mtd_info *mtd;
	void __iomem *virtadr;
	unsigned char save_control;
	unsigned char tmp, tmpb, tmpc;
	int reg, len, numchips;
	int ret = 0;

	if (!request_mem_region(physadr, DOC_IOREMAP_LEN, "DiskOnChip"))
		return -EBUSY;
	virtadr = ioremap(physadr, DOC_IOREMAP_LEN);
	if (!virtadr) {
		pr_err("Diskonchip ioremap failed: 0x%x bytes at 0x%lx\n",
		       DOC_IOREMAP_LEN, physadr);
		ret = -EIO;
		goto error_ioremap;
	}

	/* It's not possible to cleanly detect the DiskOnChip - the
	 * bootup procedure will put the device into reset mode, and
	 * it's not possible to talk to it without actually writing
	 * to the DOCControl register. So we store the current contents
	 * of the DOCControl register's location, in case we later decide
	 * that it's not a DiskOnChip, and want to put it back how we
	 * found it.
	 */
	save_control = ReadDOC(virtadr, DOCControl);

	/* Reset the DiskOnChip ASIC */
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_RESET, virtadr, DOCControl);
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_RESET, virtadr, DOCControl);

	/* Enable the DiskOnChip ASIC */
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_NORMAL, virtadr, DOCControl);
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_NORMAL, virtadr, DOCControl);

	ChipID = ReadDOC(virtadr, ChipID);

	switch (ChipID) {
	case DOC_ChipID_Doc2k:
		reg = DoC_2k_ECCStatus;
		break;
	case DOC_ChipID_DocMil:
		reg = DoC_ECCConf;
		break;
	case DOC_ChipID_DocMilPlus16:
	case DOC_ChipID_DocMilPlus32:
	case 0:
		/* Possible Millennium Plus, need to do more checks */
		/* Possibly release from power down mode */
		for (tmp = 0; (tmp < 4); tmp++)
			ReadDOC(virtadr, Mplus_Power);

		/* Reset the Millennium Plus ASIC */
		tmp = DOC_MODE_RESET | DOC_MODE_MDWREN | DOC_MODE_RST_LAT | DOC_MODE_BDECT;
		WriteDOC(tmp, virtadr, Mplus_DOCControl);
		WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);

		usleep_range(1000, 2000);
		/* Enable the Millennium Plus ASIC */
		tmp = DOC_MODE_NORMAL | DOC_MODE_MDWREN | DOC_MODE_RST_LAT | DOC_MODE_BDECT;
		WriteDOC(tmp, virtadr, Mplus_DOCControl);
		WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);
		usleep_range(1000, 2000);

		ChipID = ReadDOC(virtadr, ChipID);

		switch (ChipID) {
		case DOC_ChipID_DocMilPlus16:
			reg = DoC_Mplus_Toggle;
			break;
		case DOC_ChipID_DocMilPlus32:
			pr_err("DiskOnChip Millennium Plus 32MB is not supported, ignoring.\n");
			fallthrough;
		default:
			ret = -ENODEV;
			goto notfound;
		}
		break;

	default:
		ret = -ENODEV;
		goto notfound;
	}
	/* Check the TOGGLE bit in the ECC register */
	tmp = ReadDOC_(virtadr, reg) & DOC_TOGGLE_BIT;
	tmpb = ReadDOC_(virtadr, reg) & DOC_TOGGLE_BIT;
	tmpc = ReadDOC_(virtadr, reg) & DOC_TOGGLE_BIT;
	if ((tmp == tmpb) || (tmp != tmpc)) {
		pr_warn("Possible DiskOnChip at 0x%lx failed TOGGLE test, dropping.\n", physadr);
		ret = -ENODEV;
		goto notfound;
	}

	for (mtd = doclist; mtd; mtd = doc->nextdoc) {
		unsigned char oldval;
		unsigned char newval;
		nand = mtd_to_nand(mtd);
		doc = nand_get_controller_data(nand);
		/* Use the alias resolution register to determine if this is
		   in fact the same DOC aliased to a new address.  If writes
		   to one chip's alias resolution register change the value on
		   the other chip, they're the same chip. */
		if (ChipID == DOC_ChipID_DocMilPlus16) {
			oldval = ReadDOC(doc->virtadr, Mplus_AliasResolution);
			newval = ReadDOC(virtadr, Mplus_AliasResolution);
		} else {
			oldval = ReadDOC(doc->virtadr, AliasResolution);
			newval = ReadDOC(virtadr, AliasResolution);
		}
		if (oldval != newval)
			continue;
		if (ChipID == DOC_ChipID_DocMilPlus16) {
			WriteDOC(~newval, virtadr, Mplus_AliasResolution);
			oldval = ReadDOC(doc->virtadr, Mplus_AliasResolution);
			WriteDOC(newval, virtadr, Mplus_AliasResolution);	// restore it
		} else {
			WriteDOC(~newval, virtadr, AliasResolution);
			oldval = ReadDOC(doc->virtadr, AliasResolution);
			WriteDOC(newval, virtadr, AliasResolution);	// restore it
		}
		newval = ~newval;
		if (oldval == newval) {
			pr_debug("Found alias of DOC at 0x%lx to 0x%lx\n",
				 doc->physadr, physadr);
			goto notfound;
		}
	}

	pr_notice("DiskOnChip found at 0x%lx\n", physadr);

	len = sizeof(struct nand_chip) + sizeof(struct doc_priv) +
	      (2 * sizeof(struct nand_bbt_descr));
	nand = kzalloc(len, GFP_KERNEL);
	if (!nand) {
		ret = -ENOMEM;
		goto fail;
	}

	/*
	 * Allocate a RS codec instance
	 *
	 * Symbolsize is 10 (bits)
	 * Primitve polynomial is x^10+x^3+1
	 * First consecutive root is 510
	 * Primitve element to generate roots = 1
	 * Generator polinomial degree = 4
	 */
	doc = (struct doc_priv *) (nand + 1);
	doc->rs_decoder = init_rs(10, 0x409, FCR, 1, NROOTS);
	if (!doc->rs_decoder) {
		pr_err("DiskOnChip: Could not create a RS codec\n");
		ret = -ENOMEM;
		goto fail;
	}

	nand_controller_init(&doc->base);
	if (ChipID == DOC_ChipID_DocMilPlus16)
		doc->base.ops = &doc2001plus_ops;
	else
		doc->base.ops = &doc200x_ops;

	mtd			= nand_to_mtd(nand);
	nand->bbt_td		= (struct nand_bbt_descr *) (doc + 1);
	nand->bbt_md		= nand->bbt_td + 1;

	mtd->owner		= THIS_MODULE;
	mtd_set_ooblayout(mtd, &doc200x_ooblayout_ops);

	nand->controller	= &doc->base;
	nand_set_controller_data(nand, doc);
	nand->bbt_options	= NAND_BBT_USE_FLASH;
	/* Skip the automatic BBT scan so we can run it manually */
	nand->options		|= NAND_SKIP_BBTSCAN | NAND_NO_BBM_QUIRK;

	doc->physadr		= physadr;
	doc->virtadr		= virtadr;
	doc->ChipID		= ChipID;
	doc->curfloor		= -1;
	doc->curchip		= -1;
	doc->mh0_page		= -1;
	doc->mh1_page		= -1;
	doc->nextdoc		= doclist;

	if (ChipID == DOC_ChipID_Doc2k)
		numchips = doc2000_init(mtd);
	else if (ChipID == DOC_ChipID_DocMilPlus16)
		numchips = doc2001plus_init(mtd);
	else
		numchips = doc2001_init(mtd);

	if ((ret = nand_scan(nand, numchips)) || (ret = doc->late_init(mtd))) {
		/* DBB note: i believe nand_cleanup is necessary here, as
		   buffers may have been allocated in nand_base.  Check with
		   Thomas. FIX ME! */
		nand_cleanup(nand);
		goto fail;
	}

	/* Success! */
	doclist = mtd;
	return 0;

 notfound:
	/* Put back the contents of the DOCControl register, in case it's not
	   actually a DiskOnChip.  */
	WriteDOC(save_control, virtadr, DOCControl);
 fail:
	if (doc)
		free_rs(doc->rs_decoder);
	kfree(nand);
	iounmap(virtadr);

error_ioremap:
	release_mem_region(physadr, DOC_IOREMAP_LEN);

	return ret;
}

static void release_nanddoc(void)
{
	struct mtd_info *mtd, *nextmtd;
	struct nand_chip *nand;
	struct doc_priv *doc;
	int ret;

	for (mtd = doclist; mtd; mtd = nextmtd) {
		nand = mtd_to_nand(mtd);
		doc = nand_get_controller_data(nand);

		nextmtd = doc->nextdoc;
		ret = mtd_device_unregister(mtd);
		WARN_ON(ret);
		nand_cleanup(nand);
		iounmap(doc->virtadr);
		release_mem_region(doc->physadr, DOC_IOREMAP_LEN);
		free_rs(doc->rs_decoder);
		kfree(nand);
	}
}

static int __init init_nanddoc(void)
{
	int i, ret = 0;

	if (doc_config_location) {
		pr_info("Using configured DiskOnChip probe address 0x%lx\n",
			doc_config_location);
		ret = doc_probe(doc_config_location);
		if (ret < 0)
			return ret;
	} else {
		for (i = 0; (doc_locations[i] != 0xffffffff); i++) {
			doc_probe(doc_locations[i]);
		}
	}
	/* No banner message any more. Print a message if no DiskOnChip
	   found, so the user knows we at least tried. */
	if (!doclist) {
		pr_info("No valid DiskOnChip devices found\n");
		ret = -ENODEV;
	}
	return ret;
}

static void __exit cleanup_nanddoc(void)
{
	/* Cleanup the nand/DoC resources */
	release_nanddoc();
}

module_init(init_nanddoc);
module_exit(cleanup_nanddoc);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("M-Systems DiskOnChip 2000, Millennium and Millennium Plus device driver");