/*
 * Handles the M-Systems DiskOnChip G3 chip
 *
 * Copyright (C) 2011 Robert Jarzmik
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/platform_device.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>

#include <linux/debugfs.h>
#include <linux/seq_file.h>

#define CREATE_TRACE_POINTS
#include "docg3.h"

/*
 * This driver handles the DiskOnChip G3 flash memory.
 *
 * As no specification is available from M-Systems/Sandisk, this drivers lacks
 * several functions available on the chip, as :
 *  - block erase
 *  - page write
 *  - IPL write
 *  - ECC fixing (lack of BCH algorith understanding)
 *  - powerdown / powerup
 *
 * The bus data width (8bits versus 16bits) is not handled (if_cfg flag), and
 * the driver assumes a 16bits data bus.
 *
 * DocG3 relies on 2 ECC algorithms, which are handled in hardware :
 *  - a 1 byte Hamming code stored in the OOB for each page
 *  - a 7 bytes BCH code stored in the OOB for each page
 * The BCH part is only used for check purpose, no correction is available as
 * some information is missing. What is known is that :
 *  - BCH is in GF(2^14)
 *  - BCH is over data of 520 bytes (512 page + 7 page_info bytes
 *                                   + 1 hamming byte)
 *  - BCH can correct up to 4 bits (t = 4)
 *  - BCH syndroms are calculated in hardware, and checked in hardware as well
 *
 */

static inline u8 doc_readb(struct docg3 *docg3, u16 reg)
{
        u8 val = readb(docg3->base + reg);

        trace_docg3_io(0, 8, reg, (int)val);
        return val;
}

static inline u16 doc_readw(struct docg3 *docg3, u16 reg)
{
        u16 val = readw(docg3->base + reg);

        trace_docg3_io(0, 16, reg, (int)val);
        return val;
}

static inline void doc_writeb(struct docg3 *docg3, u8 val, u16 reg)
{
        writeb(val, docg3->base + reg);
        trace_docg3_io(1, 16, reg, val);
}

static inline void doc_writew(struct docg3 *docg3, u16 val, u16 reg)
{
        writew(val, docg3->base + reg);
        trace_docg3_io(1, 16, reg, val);
}

static inline void doc_flash_command(struct docg3 *docg3, u8 cmd)
{
        doc_writeb(docg3, cmd, DOC_FLASHCOMMAND);
}

static inline void doc_flash_sequence(struct docg3 *docg3, u8 seq)
{
        doc_writeb(docg3, seq, DOC_FLASHSEQUENCE);
}

static inline void doc_flash_address(struct docg3 *docg3, u8 addr)
{
        doc_writeb(docg3, addr, DOC_FLASHADDRESS);
}

static char const *part_probes[] = { "cmdlinepart", "saftlpart", NULL };

static int doc_register_readb(struct docg3 *docg3, int reg)
{
        u8 val;

        doc_writew(docg3, reg, DOC_READADDRESS);
        val = doc_readb(docg3, reg);
        doc_vdbg("Read register %04x : %02x\n", reg, val);
        return val;
}

static int doc_register_readw(struct docg3 *docg3, int reg)
{
        u16 val;

        doc_writew(docg3, reg, DOC_READADDRESS);
        val = doc_readw(docg3, reg);
        doc_vdbg("Read register %04x : %04x\n", reg, val);
        return val;
}

/**
 * doc_delay - delay docg3 operations
 * @docg3: the device
 * @nbNOPs: the number of NOPs to issue
 *
 * As no specification is available, the right timings between chip commands are
 * unknown. The only available piece of information are the observed nops on a
 * working docg3 chip.
 * Therefore, doc_delay relies on a busy loop of NOPs, instead of scheduler
 * friendlier msleep() functions or blocking mdelay().
 */
static void doc_delay(struct docg3 *docg3, int nbNOPs)
{
        int i;

        doc_dbg("NOP x %d\n", nbNOPs);
        for (i = 0; i < nbNOPs; i++)
                doc_writeb(docg3, 0, DOC_NOP);
}

static int is_prot_seq_error(struct docg3 *docg3)
{
        int ctrl;

        ctrl = doc_register_readb(docg3, DOC_FLASHCONTROL);
        return ctrl & (DOC_CTRL_PROTECTION_ERROR | DOC_CTRL_SEQUENCE_ERROR);
}

static int doc_is_ready(struct docg3 *docg3)
{
        int ctrl;

        ctrl = doc_register_readb(docg3, DOC_FLASHCONTROL);
        return ctrl & DOC_CTRL_FLASHREADY;
}

static int doc_wait_ready(struct docg3 *docg3)
{
        int maxWaitCycles = 100;

        do {
                doc_delay(docg3, 4);
                cpu_relax();
        } while (!doc_is_ready(docg3) && maxWaitCycles--);
        doc_delay(docg3, 2);
        if (maxWaitCycles > 0)
                return 0;
        else
                return -EIO;
}

static int doc_reset_seq(struct docg3 *docg3)
{
        int ret;

        doc_writeb(docg3, 0x10, DOC_FLASHCONTROL);
        doc_flash_sequence(docg3, DOC_SEQ_RESET);
        doc_flash_command(docg3, DOC_CMD_RESET);
        doc_delay(docg3, 2);
        ret = doc_wait_ready(docg3);

        doc_dbg("doc_reset_seq() -> isReady=%s\n", ret ? "false" : "true");
        return ret;
}

/**
 * doc_read_data_area - Read data from data area
 * @docg3: the device
 * @buf: the buffer to fill in
 * @len: the lenght to read
 * @first: first time read, DOC_READADDRESS should be set
 *
 * Reads bytes from flash data. Handles the single byte / even bytes reads.
 */
static void doc_read_data_area(struct docg3 *docg3, void *buf, int len,
                               int first)
{
        int i, cdr, len4;
        u16 data16, *dst16;
        u8 data8, *dst8;

        doc_dbg("doc_read_data_area(buf=%p, len=%d)\n", buf, len);
        cdr = len & 0x3;
        len4 = len - cdr;

        if (first)
                doc_writew(docg3, DOC_IOSPACE_DATA, DOC_READADDRESS);
        dst16 = buf;
        for (i = 0; i < len4; i += 2) {
                data16 = doc_readw(docg3, DOC_IOSPACE_DATA);
                *dst16 = data16;
                dst16++;
        }

        if (cdr) {
                doc_writew(docg3, DOC_IOSPACE_DATA | DOC_READADDR_ONE_BYTE,
                           DOC_READADDRESS);
                doc_delay(docg3, 1);
                dst8 = (u8 *)dst16;
                for (i = 0; i < cdr; i++) {
                        data8 = doc_readb(docg3, DOC_IOSPACE_DATA);
                        *dst8 = data8;
                        dst8++;
                }
        }
}

/**
 * doc_set_data_mode - Sets the flash to reliable data mode
 * @docg3: the device
 *
 * The reliable data mode is a bit slower than the fast mode, but less errors
 * occur.  Entering the reliable mode cannot be done without entering the fast
 * mode first.
 */
static void doc_set_reliable_mode(struct docg3 *docg3)
{
        doc_dbg("doc_set_reliable_mode()\n");
        doc_flash_sequence(docg3, DOC_SEQ_SET_MODE);
        doc_flash_command(docg3, DOC_CMD_FAST_MODE);
        doc_flash_command(docg3, DOC_CMD_RELIABLE_MODE);
        doc_delay(docg3, 2);
}

/**
 * doc_set_asic_mode - Set the ASIC mode
 * @docg3: the device
 * @mode: the mode
 *
 * The ASIC can work in 3 modes :
 *  - RESET: all registers are zeroed
 *  - NORMAL: receives and handles commands
 *  - POWERDOWN: minimal poweruse, flash parts shut off
 */
static void doc_set_asic_mode(struct docg3 *docg3, u8 mode)
{
        int i;

        for (i = 0; i < 12; i++)
                doc_readb(docg3, DOC_IOSPACE_IPL);

        mode |= DOC_ASICMODE_MDWREN;
        doc_dbg("doc_set_asic_mode(%02x)\n", mode);
        doc_writeb(docg3, mode, DOC_ASICMODE);
        doc_writeb(docg3, ~mode, DOC_ASICMODECONFIRM);
        doc_delay(docg3, 1);
}

/**
 * doc_set_device_id - Sets the devices id for cascaded G3 chips
 * @docg3: the device
 * @id: the chip to select (amongst 0, 1, 2, 3)
 *
 * There can be 4 cascaded G3 chips. This function selects the one which will
 * should be the active one.
 */
static void doc_set_device_id(struct docg3 *docg3, int id)
{
        u8 ctrl;

        doc_dbg("doc_set_device_id(%d)\n", id);
        doc_writeb(docg3, id, DOC_DEVICESELECT);
        ctrl = doc_register_readb(docg3, DOC_FLASHCONTROL);

        ctrl &= ~DOC_CTRL_VIOLATION;
        ctrl |= DOC_CTRL_CE;
        doc_writeb(docg3, ctrl, DOC_FLASHCONTROL);
}

/**
 * doc_set_extra_page_mode - Change flash page layout
 * @docg3: the device
 *
 * Normally, the flash page is split into the data (512 bytes) and the out of
 * band data (16 bytes). For each, 4 more bytes can be accessed, where the wear
 * leveling counters are stored.  To access this last area of 4 bytes, a special
 * mode must be input to the flash ASIC.
 *
 * Returns 0 if no error occured, -EIO else.
 */
static int doc_set_extra_page_mode(struct docg3 *docg3)
{
        int fctrl;

        doc_dbg("doc_set_extra_page_mode()\n");
        doc_flash_sequence(docg3, DOC_SEQ_PAGE_SIZE_532);
        doc_flash_command(docg3, DOC_CMD_PAGE_SIZE_532);
        doc_delay(docg3, 2);

        fctrl = doc_register_readb(docg3, DOC_FLASHCONTROL);
        if (fctrl & (DOC_CTRL_PROTECTION_ERROR | DOC_CTRL_SEQUENCE_ERROR))
                return -EIO;
        else
                return 0;
}

/**
 * doc_seek - Set both flash planes to the specified block, page for reading
 * @docg3: the device
 * @block0: the first plane block index
 * @block1: the second plane block index
 * @page: the page index within the block
 * @wear: if true, read will occur on the 4 extra bytes of the wear area
 * @ofs: offset in page to read
 *
 * Programs the flash even and odd planes to the specific block and page.
 * Alternatively, programs the flash to the wear area of the specified page.
 */
static int doc_read_seek(struct docg3 *docg3, int block0, int block1, int page,
                         int wear, int ofs)
{
        int sector, ret = 0;

        doc_dbg("doc_seek(blocks=(%d,%d), page=%d, ofs=%d, wear=%d)\n",
                block0, block1, page, ofs, wear);

        if (!wear && (ofs < 2 * DOC_LAYOUT_PAGE_SIZE)) {
                doc_flash_sequence(docg3, DOC_SEQ_SET_PLANE1);
                doc_flash_command(docg3, DOC_CMD_READ_PLANE1);
                doc_delay(docg3, 2);
        } else {
                doc_flash_sequence(docg3, DOC_SEQ_SET_PLANE2);
                doc_flash_command(docg3, DOC_CMD_READ_PLANE2);
                doc_delay(docg3, 2);
        }

        doc_set_reliable_mode(docg3);
        if (wear)
                ret = doc_set_extra_page_mode(docg3);
        if (ret)
                goto out;

        sector = (block0 << DOC_ADDR_BLOCK_SHIFT) + (page & DOC_ADDR_PAGE_MASK);
        doc_flash_sequence(docg3, DOC_SEQ_READ);
        doc_flash_command(docg3, DOC_CMD_PROG_BLOCK_ADDR);
        doc_delay(docg3, 1);
        doc_flash_address(docg3, sector & 0xff);
        doc_flash_address(docg3, (sector >> 8) & 0xff);
        doc_flash_address(docg3, (sector >> 16) & 0xff);
        doc_delay(docg3, 1);

        sector = (block1 << DOC_ADDR_BLOCK_SHIFT) + (page & DOC_ADDR_PAGE_MASK);
        doc_flash_command(docg3, DOC_CMD_PROG_BLOCK_ADDR);
        doc_delay(docg3, 1);
        doc_flash_address(docg3, sector & 0xff);
        doc_flash_address(docg3, (sector >> 8) & 0xff);
        doc_flash_address(docg3, (sector >> 16) & 0xff);
        doc_delay(docg3, 2);

out:
        return ret;
}

/**
 * doc_read_page_ecc_init - Initialize hardware ECC engine
 * @docg3: the device
 * @len: the number of bytes covered by the ECC (BCH covered)
 *
 * The function does initialize the hardware ECC engine to compute the Hamming
 * ECC (on 1 byte) and the BCH Syndroms (on 7 bytes).
 *
 * Return 0 if succeeded, -EIO on error
 */
static int doc_read_page_ecc_init(struct docg3 *docg3, int len)
{
        doc_writew(docg3, DOC_ECCCONF0_READ_MODE
                   | DOC_ECCCONF0_BCH_ENABLE | DOC_ECCCONF0_HAMMING_ENABLE
                   | (len & DOC_ECCCONF0_DATA_BYTES_MASK),
                   DOC_ECCCONF0);
        doc_delay(docg3, 4);
        doc_register_readb(docg3, DOC_FLASHCONTROL);
        return doc_wait_ready(docg3);
}

/**
 * doc_read_page_prepare - Prepares reading data from a flash page
 * @docg3: the device
 * @block0: the first plane block index on flash memory
 * @block1: the second plane block index on flash memory
 * @page: the page index in the block
 * @offset: the offset in the page (must be a multiple of 4)
 *
 * Prepares the page to be read in the flash memory :
 *   - tell ASIC to map the flash pages
 *   - tell ASIC to be in read mode
 *
 * After a call to this method, a call to doc_read_page_finish is mandatory,
 * to end the read cycle of the flash.
 *
 * Read data from a flash page. The length to be read must be between 0 and
 * (page_size + oob_size + wear_size), ie. 532, and a multiple of 4 (because
 * the extra bytes reading is not implemented).
 *
 * As pages are grouped by 2 (in 2 planes), reading from a page must be done
 * in two steps:
 *  - one read of 512 bytes at offset 0
 *  - one read of 512 bytes at offset 512 + 16
 *
 * Returns 0 if successful, -EIO if a read error occured.
 */
static int doc_read_page_prepare(struct docg3 *docg3, int block0, int block1,
                                 int page, int offset)
{
        int wear_area = 0, ret = 0;

        doc_dbg("doc_read_page_prepare(blocks=(%d,%d), page=%d, ofsInPage=%d)\n",
                block0, block1, page, offset);
        if (offset >= DOC_LAYOUT_WEAR_OFFSET)
                wear_area = 1;
        if (!wear_area && offset > (DOC_LAYOUT_PAGE_OOB_SIZE * 2))
                return -EINVAL;

        doc_set_device_id(docg3, docg3->device_id);
        ret = doc_reset_seq(docg3);
        if (ret)
                goto err;

        /* Program the flash address block and page */
        ret = doc_read_seek(docg3, block0, block1, page, wear_area, offset);
        if (ret)
                goto err;

        doc_flash_command(docg3, DOC_CMD_READ_ALL_PLANES);
        doc_delay(docg3, 2);
        doc_wait_ready(docg3);

        doc_flash_command(docg3, DOC_CMD_SET_ADDR_READ);
        doc_delay(docg3, 1);
        if (offset >= DOC_LAYOUT_PAGE_SIZE * 2)
                offset -= 2 * DOC_LAYOUT_PAGE_SIZE;
        doc_flash_address(docg3, offset >> 2);
        doc_delay(docg3, 1);
        doc_wait_ready(docg3);

        doc_flash_command(docg3, DOC_CMD_READ_FLASH);

        return 0;
err:
        doc_writeb(docg3, 0, DOC_DATAEND);
        doc_delay(docg3, 2);
        return -EIO;
}

/**
 * doc_read_page_getbytes - Reads bytes from a prepared page
 * @docg3: the device
 * @len: the number of bytes to be read (must be a multiple of 4)
 * @buf: the buffer to be filled in
 * @first: 1 if first time read, DOC_READADDRESS should be set
 *
 */
static int doc_read_page_getbytes(struct docg3 *docg3, int len, u_char *buf,
                                  int first)
{
        doc_read_data_area(docg3, buf, len, first);
        doc_delay(docg3, 2);
        return len;
}

/**
 * doc_get_hw_bch_syndroms - Get hardware calculated BCH syndroms
 * @docg3: the device
 * @syns:  the array of 7 integers where the syndroms will be stored
 */
static void doc_get_hw_bch_syndroms(struct docg3 *docg3, int *syns)
{
        int i;

        for (i = 0; i < DOC_ECC_BCH_SIZE; i++)
                syns[i] = doc_register_readb(docg3, DOC_BCH_SYNDROM(i));
}

/**
 * doc_read_page_finish - Ends reading of a flash page
 * @docg3: the device
 *
 * As a side effect, resets the chip selector to 0. This ensures that after each
 * read operation, the floor 0 is selected. Therefore, if the systems halts, the
 * reboot will boot on floor 0, where the IPL is.
 */
static void doc_read_page_finish(struct docg3 *docg3)
{
        doc_writeb(docg3, 0, DOC_DATAEND);
        doc_delay(docg3, 2);
        doc_set_device_id(docg3, 0);
}

/**
 * calc_block_sector - Calculate blocks, pages and ofs.

 * @from: offset in flash
 * @block0: first plane block index calculated
 * @block1: second plane block index calculated
 * @page: page calculated
 * @ofs: offset in page
 */
static void calc_block_sector(loff_t from, int *block0, int *block1, int *page,
                              int *ofs)
{
        uint sector;

        sector = from / DOC_LAYOUT_PAGE_SIZE;
        *block0 = sector / (DOC_LAYOUT_PAGES_PER_BLOCK * DOC_LAYOUT_NBPLANES)
                * DOC_LAYOUT_NBPLANES;
        *block1 = *block0 + 1;
        *page = sector % (DOC_LAYOUT_PAGES_PER_BLOCK * DOC_LAYOUT_NBPLANES);
        *page /= DOC_LAYOUT_NBPLANES;
        if (sector % 2)
                *ofs = DOC_LAYOUT_PAGE_OOB_SIZE;
        else
                *ofs = 0;
}

/**
 * doc_read - Read bytes from flash
 * @mtd: the device
 * @from: the offset from first block and first page, in bytes, aligned on page
 *        size
 * @len: the number of bytes to read (must be a multiple of 4)
 * @retlen: the number of bytes actually read
 * @buf: the filled in buffer
 *
 * Reads flash memory pages. This function does not read the OOB chunk, but only
 * the page data.
 *
 * Returns 0 if read successfull, of -EIO, -EINVAL if an error occured
 */
static int doc_read(struct mtd_info *mtd, loff_t from, size_t len,
             size_t *retlen, u_char *buf)
{
        struct docg3 *docg3 = mtd->priv;
        int block0, block1, page, readlen, ret, ofs = 0;
        int syn[DOC_ECC_BCH_SIZE], eccconf1;
        u8 oob[DOC_LAYOUT_OOB_SIZE];

        ret = -EINVAL;
        doc_dbg("doc_read(from=%lld, len=%zu, buf=%p)\n", from, len, buf);
        if (from % DOC_LAYOUT_PAGE_SIZE)
                goto err;
        if (len % 4)
                goto err;
        calc_block_sector(from, &block0, &block1, &page, &ofs);
        if (block1 > docg3->max_block)
                goto err;

        *retlen = 0;
        ret = 0;
        readlen = min_t(size_t, len, (size_t)DOC_LAYOUT_PAGE_SIZE);
        while (!ret && len > 0) {
                readlen = min_t(size_t, len, (size_t)DOC_LAYOUT_PAGE_SIZE);
                ret = doc_read_page_prepare(docg3, block0, block1, page, ofs);
                if (ret < 0)
                        goto err;
                ret = doc_read_page_ecc_init(docg3, DOC_ECC_BCH_COVERED_BYTES);
                if (ret < 0)
                        goto err_in_read;
                ret = doc_read_page_getbytes(docg3, readlen, buf, 1);
                if (ret < readlen)
                        goto err_in_read;
                ret = doc_read_page_getbytes(docg3, DOC_LAYOUT_OOB_SIZE,
                                             oob, 0);
                if (ret < DOC_LAYOUT_OOB_SIZE)
                        goto err_in_read;

                *retlen += readlen;
                buf += readlen;
                len -= readlen;

                ofs ^= DOC_LAYOUT_PAGE_OOB_SIZE;
                if (ofs == 0)
                        page += 2;
                if (page > DOC_ADDR_PAGE_MASK) {
                        page = 0;
                        block0 += 2;
                        block1 += 2;
                }

                /*
                 * There should be a BCH bitstream fixing algorithm here ...
                 * By now, a page read failure is triggered by BCH error
                 */
                doc_get_hw_bch_syndroms(docg3, syn);
                eccconf1 = doc_register_readb(docg3, DOC_ECCCONF1);

                doc_dbg("OOB - INFO: %02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
                         oob[0], oob[1], oob[2], oob[3], oob[4],
                         oob[5], oob[6]);
                doc_dbg("OOB - HAMMING: %02x\n", oob[7]);
                doc_dbg("OOB - BCH_ECC: %02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
                         oob[8], oob[9], oob[10], oob[11], oob[12],
                         oob[13], oob[14]);
                doc_dbg("OOB - UNUSED: %02x\n", oob[15]);
                doc_dbg("ECC checks: ECCConf1=%x\n", eccconf1);
                doc_dbg("ECC BCH syndrom: %02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
                        syn[0], syn[1], syn[2], syn[3], syn[4], syn[5], syn[6]);

                ret = -EBADMSG;
                if (block0 >= DOC_LAYOUT_BLOCK_FIRST_DATA) {
                        if (eccconf1 & DOC_ECCCONF1_BCH_SYNDROM_ERR)
                                goto err_in_read;
                        if (is_prot_seq_error(docg3))
                                goto err_in_read;
                }
                doc_read_page_finish(docg3);
        }

        return 0;
err_in_read:
        doc_read_page_finish(docg3);
err:
        return ret;
}

/**
 * doc_read_oob - Read out of band bytes from flash
 * @mtd: the device
 * @from: the offset from first block and first page, in bytes, aligned on page
 *        size
 * @ops: the mtd oob structure
 *
 * Reads flash memory OOB area of pages.
 *
 * Returns 0 if read successfull, of -EIO, -EINVAL if an error occured
 */
static int doc_read_oob(struct mtd_info *mtd, loff_t from,
                        struct mtd_oob_ops *ops)
{
        struct docg3 *docg3 = mtd->priv;
        int block0, block1, page, ofs, ret;
        u8 *buf = ops->oobbuf;
        size_t len = ops->ooblen;

        doc_dbg("doc_read_oob(from=%lld, buf=%p, len=%zu)\n", from, buf, len);
        if (len != DOC_LAYOUT_OOB_SIZE)
                return -EINVAL;

        switch (ops->mode) {
        case MTD_OPS_PLACE_OOB:
                buf += ops->ooboffs;
                break;
        default:
                break;
        }

        calc_block_sector(from, &block0, &block1, &page, &ofs);
        if (block1 > docg3->max_block)
                return -EINVAL;

        ret = doc_read_page_prepare(docg3, block0, block1, page,
                                    ofs + DOC_LAYOUT_PAGE_SIZE);
        if (!ret)
                ret = doc_read_page_ecc_init(docg3, DOC_LAYOUT_OOB_SIZE);
        if (!ret)
                ret = doc_read_page_getbytes(docg3, DOC_LAYOUT_OOB_SIZE,
                                             buf, 1);
        doc_read_page_finish(docg3);

        if (ret > 0)
                ops->oobretlen = ret;
        else
                ops->oobretlen = 0;
        return (ret > 0) ? 0 : ret;
}

static int doc_reload_bbt(struct docg3 *docg3)
{
        int block = DOC_LAYOUT_BLOCK_BBT;
        int ret = 0, nbpages, page;
        u_char *buf = docg3->bbt;

        nbpages = DIV_ROUND_UP(docg3->max_block + 1, 8 * DOC_LAYOUT_PAGE_SIZE);
        for (page = 0; !ret && (page < nbpages); page++) {
                ret = doc_read_page_prepare(docg3, block, block + 1,
                                            page + DOC_LAYOUT_PAGE_BBT, 0);
                if (!ret)
                        ret = doc_read_page_ecc_init(docg3,
                                                     DOC_LAYOUT_PAGE_SIZE);
                if (!ret)
                        doc_read_page_getbytes(docg3, DOC_LAYOUT_PAGE_SIZE,
                                               buf, 1);
                buf += DOC_LAYOUT_PAGE_SIZE;
        }
        doc_read_page_finish(docg3);
        return ret;
}

/**
 * doc_block_isbad - Checks whether a block is good or not
 * @mtd: the device
 * @from: the offset to find the correct block
 *
 * Returns 1 if block is bad, 0 if block is good
 */
static int doc_block_isbad(struct mtd_info *mtd, loff_t from)
{
        struct docg3 *docg3 = mtd->priv;
        int block0, block1, page, ofs, is_good;

        calc_block_sector(from, &block0, &block1, &page, &ofs);
        doc_dbg("doc_block_isbad(from=%lld) => block=(%d,%d), page=%d, ofs=%d\n",
                from, block0, block1, page, ofs);

        if (block0 < DOC_LAYOUT_BLOCK_FIRST_DATA)
                return 0;
        if (block1 > docg3->max_block)
                return -EINVAL;

        is_good = docg3->bbt[block0 >> 3] & (1 << (block0 & 0x7));
        return !is_good;
}

/**
 * doc_get_erase_count - Get block erase count
 * @docg3: the device
 * @from: the offset in which the block is.
 *
 * Get the number of times a block was erased. The number is the maximum of
 * erase times between first and second plane (which should be equal normally).
 *
 * Returns The number of erases, or -EINVAL or -EIO on error.
 */
static int doc_get_erase_count(struct docg3 *docg3, loff_t from)
{
        u8 buf[DOC_LAYOUT_WEAR_SIZE];
        int ret, plane1_erase_count, plane2_erase_count;
        int block0, block1, page, ofs;

        doc_dbg("doc_get_erase_count(from=%lld, buf=%p)\n", from, buf);
        if (from % DOC_LAYOUT_PAGE_SIZE)
                return -EINVAL;
        calc_block_sector(from, &block0, &block1, &page, &ofs);
        if (block1 > docg3->max_block)
                return -EINVAL;

        ret = doc_reset_seq(docg3);
        if (!ret)
                ret = doc_read_page_prepare(docg3, block0, block1, page,
                                            ofs + DOC_LAYOUT_WEAR_OFFSET);
        if (!ret)
                ret = doc_read_page_getbytes(docg3, DOC_LAYOUT_WEAR_SIZE,
                                             buf, 1);
        doc_read_page_finish(docg3);

        if (ret || (buf[0] != DOC_ERASE_MARK) || (buf[2] != DOC_ERASE_MARK))
                return -EIO;
        plane1_erase_count = (u8)(~buf[1]) | ((u8)(~buf[4]) << 8)
                | ((u8)(~buf[5]) << 16);
        plane2_erase_count = (u8)(~buf[3]) | ((u8)(~buf[6]) << 8)
                | ((u8)(~buf[7]) << 16);

        return max(plane1_erase_count, plane2_erase_count);
}

/*
 * Debug sysfs entries
 */
static int dbg_flashctrl_show(struct seq_file *s, void *p)
{
        struct docg3 *docg3 = (struct docg3 *)s->private;

        int pos = 0;
        u8 fctrl = doc_register_readb(docg3, DOC_FLASHCONTROL);

        pos += seq_printf(s,
                 "FlashControl : 0x%02x (%s,CE# %s,%s,%s,flash %s)\n",
                 fctrl,
                 fctrl & DOC_CTRL_VIOLATION ? "protocol violation" : "-",
                 fctrl & DOC_CTRL_CE ? "active" : "inactive",
                 fctrl & DOC_CTRL_PROTECTION_ERROR ? "protection error" : "-",
                 fctrl & DOC_CTRL_SEQUENCE_ERROR ? "sequence error" : "-",
                 fctrl & DOC_CTRL_FLASHREADY ? "ready" : "not ready");
        return pos;
}
DEBUGFS_RO_ATTR(flashcontrol, dbg_flashctrl_show);

static int dbg_asicmode_show(struct seq_file *s, void *p)
{
        struct docg3 *docg3 = (struct docg3 *)s->private;

        int pos = 0;
        int pctrl = doc_register_readb(docg3, DOC_ASICMODE);
        int mode = pctrl & 0x03;

        pos += seq_printf(s,
                         "%04x : RAM_WE=%d,RSTIN_RESET=%d,BDETCT_RESET=%d,WRITE_ENABLE=%d,POWERDOWN=%d,MODE=%d%d (",
                         pctrl,
                         pctrl & DOC_ASICMODE_RAM_WE ? 1 : 0,
                         pctrl & DOC_ASICMODE_RSTIN_RESET ? 1 : 0,
                         pctrl & DOC_ASICMODE_BDETCT_RESET ? 1 : 0,
                         pctrl & DOC_ASICMODE_MDWREN ? 1 : 0,
                         pctrl & DOC_ASICMODE_POWERDOWN ? 1 : 0,
                         mode >> 1, mode & 0x1);

        switch (mode) {
        case DOC_ASICMODE_RESET:
                pos += seq_printf(s, "reset");
                break;
        case DOC_ASICMODE_NORMAL:
                pos += seq_printf(s, "normal");
                break;
        case DOC_ASICMODE_POWERDOWN:
                pos += seq_printf(s, "powerdown");
                break;
        }
        pos += seq_printf(s, ")\n");
        return pos;
}
DEBUGFS_RO_ATTR(asic_mode, dbg_asicmode_show);

static int dbg_device_id_show(struct seq_file *s, void *p)
{
        struct docg3 *docg3 = (struct docg3 *)s->private;
        int pos = 0;
        int id = doc_register_readb(docg3, DOC_DEVICESELECT);

        pos += seq_printf(s, "DeviceId = %d\n", id);
        return pos;
}
DEBUGFS_RO_ATTR(device_id, dbg_device_id_show);

static int dbg_protection_show(struct seq_file *s, void *p)
{
        struct docg3 *docg3 = (struct docg3 *)s->private;
        int pos = 0;
        int protect = doc_register_readb(docg3, DOC_PROTECTION);
        int dps0 = doc_register_readb(docg3, DOC_DPS0_STATUS);
        int dps0_low = doc_register_readb(docg3, DOC_DPS0_ADDRLOW);
        int dps0_high = doc_register_readb(docg3, DOC_DPS0_ADDRHIGH);
        int dps1 = doc_register_readb(docg3, DOC_DPS1_STATUS);
        int dps1_low = doc_register_readb(docg3, DOC_DPS1_ADDRLOW);
        int dps1_high = doc_register_readb(docg3, DOC_DPS1_ADDRHIGH);

        pos += seq_printf(s, "Protection = 0x%02x (",
                         protect);
        if (protect & DOC_PROTECT_FOUNDRY_OTP_LOCK)
                pos += seq_printf(s, "FOUNDRY_OTP_LOCK,");
        if (protect & DOC_PROTECT_CUSTOMER_OTP_LOCK)
                pos += seq_printf(s, "CUSTOMER_OTP_LOCK,");
        if (protect & DOC_PROTECT_LOCK_INPUT)
                pos += seq_printf(s, "LOCK_INPUT,");
        if (protect & DOC_PROTECT_STICKY_LOCK)
                pos += seq_printf(s, "STICKY_LOCK,");
        if (protect & DOC_PROTECT_PROTECTION_ENABLED)
                pos += seq_printf(s, "PROTECTION ON,");
        if (protect & DOC_PROTECT_IPL_DOWNLOAD_LOCK)
                pos += seq_printf(s, "IPL_DOWNLOAD_LOCK,");
        if (protect & DOC_PROTECT_PROTECTION_ERROR)
                pos += seq_printf(s, "PROTECT_ERR,");
        else
                pos += seq_printf(s, "NO_PROTECT_ERR");
        pos += seq_printf(s, ")\n");

        pos += seq_printf(s, "DPS0 = 0x%02x : "
                         "Protected area [0x%x - 0x%x] : OTP=%d, READ=%d, "
                         "WRITE=%d, HW_LOCK=%d, KEY_OK=%d\n",
                         dps0, dps0_low, dps0_high,
                         !!(dps0 & DOC_DPS_OTP_PROTECTED),
                         !!(dps0 & DOC_DPS_READ_PROTECTED),
                         !!(dps0 & DOC_DPS_WRITE_PROTECTED),
                         !!(dps0 & DOC_DPS_HW_LOCK_ENABLED),
                         !!(dps0 & DOC_DPS_KEY_OK));
        pos += seq_printf(s, "DPS1 = 0x%02x : "
                         "Protected area [0x%x - 0x%x] : OTP=%d, READ=%d, "
                         "WRITE=%d, HW_LOCK=%d, KEY_OK=%d\n",
                         dps1, dps1_low, dps1_high,
                         !!(dps1 & DOC_DPS_OTP_PROTECTED),
                         !!(dps1 & DOC_DPS_READ_PROTECTED),
                         !!(dps1 & DOC_DPS_WRITE_PROTECTED),
                         !!(dps1 & DOC_DPS_HW_LOCK_ENABLED),
                         !!(dps1 & DOC_DPS_KEY_OK));
        return pos;
}
DEBUGFS_RO_ATTR(protection, dbg_protection_show);

static int __init doc_dbg_register(struct docg3 *docg3)
{
        struct dentry *root, *entry;

        root = debugfs_create_dir("docg3", NULL);
        if (!root)
                return -ENOMEM;

        entry = debugfs_create_file("flashcontrol", S_IRUSR, root, docg3,
                                  &flashcontrol_fops);
        if (entry)
                entry = debugfs_create_file("asic_mode", S_IRUSR, root,
                                            docg3, &asic_mode_fops);
        if (entry)
                entry = debugfs_create_file("device_id", S_IRUSR, root,
                                            docg3, &device_id_fops);
        if (entry)
                entry = debugfs_create_file("protection", S_IRUSR, root,
                                            docg3, &protection_fops);
        if (entry) {
                docg3->debugfs_root = root;
                return 0;
        } else {
                debugfs_remove_recursive(root);
                return -ENOMEM;
        }
}

static void __exit doc_dbg_unregister(struct docg3 *docg3)
{
        debugfs_remove_recursive(docg3->debugfs_root);
}

/**
 * doc_set_driver_info - Fill the mtd_info structure and docg3 structure
 * @chip_id: The chip ID of the supported chip
 * @mtd: The structure to fill
 */
static void __init doc_set_driver_info(int chip_id, struct mtd_info *mtd)
{
        struct docg3 *docg3 = mtd->priv;
        int cfg;

        cfg = doc_register_readb(docg3, DOC_CONFIGURATION);
        docg3->if_cfg = (cfg & DOC_CONF_IF_CFG ? 1 : 0);

        switch (chip_id) {
        case DOC_CHIPID_G3:
                mtd->name = "DiskOnChip G3";
                docg3->max_block = 2047;
                break;
        }
        mtd->type = MTD_NANDFLASH;
        /*
         * Once write methods are added, the correct flags will be set.
         * mtd->flags = MTD_CAP_NANDFLASH;
         */
        mtd->flags = MTD_CAP_ROM;
        mtd->size = (docg3->max_block + 1) * DOC_LAYOUT_BLOCK_SIZE;
        mtd->erasesize = DOC_LAYOUT_BLOCK_SIZE * DOC_LAYOUT_NBPLANES;
        mtd->writesize = DOC_LAYOUT_PAGE_SIZE;
        mtd->oobsize = DOC_LAYOUT_OOB_SIZE;
        mtd->owner = THIS_MODULE;
        mtd->erase = NULL;
        mtd->point = NULL;
        mtd->unpoint = NULL;
        mtd->read = doc_read;
        mtd->write = NULL;
        mtd->read_oob = doc_read_oob;
        mtd->write_oob = NULL;
        mtd->sync = NULL;
        mtd->block_isbad = doc_block_isbad;
}

/**
 * doc_probe - Probe the IO space for a DiskOnChip G3 chip
 * @pdev: platform device
 *
 * Probes for a G3 chip at the specified IO space in the platform data
 * ressources.
 *
 * Returns 0 on success, -ENOMEM, -ENXIO on error
 */
static int __init docg3_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct docg3 *docg3;
        struct mtd_info *mtd;
        struct resource *ress;
        int ret, bbt_nbpages;
        u16 chip_id, chip_id_inv;

        ret = -ENOMEM;
        docg3 = kzalloc(sizeof(struct docg3), GFP_KERNEL);
        if (!docg3)
                goto nomem1;

        mtd = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
        if (!mtd)
                goto nomem2;
        mtd->priv = docg3;

        ret = -ENXIO;
        ress = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!ress) {
                dev_err(dev, "No I/O memory resource defined\n");
                goto noress;
        }
        docg3->base = ioremap(ress->start, DOC_IOSPACE_SIZE);

        docg3->dev = &pdev->dev;
        docg3->device_id = 0;
        doc_set_device_id(docg3, docg3->device_id);
        doc_set_asic_mode(docg3, DOC_ASICMODE_RESET);
        doc_set_asic_mode(docg3, DOC_ASICMODE_NORMAL);

        chip_id = doc_register_readw(docg3, DOC_CHIPID);
        chip_id_inv = doc_register_readw(docg3, DOC_CHIPID_INV);

        ret = -ENODEV;
        if (chip_id != (u16)(~chip_id_inv)) {
                doc_info("No device found at IO addr %p\n",
                         (void *)ress->start);
                goto nochipfound;
        }

        switch (chip_id) {
        case DOC_CHIPID_G3:
                doc_info("Found a G3 DiskOnChip at addr %p\n",
                         (void *)ress->start);
                break;
        default:
                doc_err("Chip id %04x is not a DiskOnChip G3 chip\n", chip_id);
                goto nochipfound;
        }

        doc_set_driver_info(chip_id, mtd);
        platform_set_drvdata(pdev, mtd);

        ret = -ENOMEM;
        bbt_nbpages = DIV_ROUND_UP(docg3->max_block + 1,
                                   8 * DOC_LAYOUT_PAGE_SIZE);
        docg3->bbt = kzalloc(bbt_nbpages * DOC_LAYOUT_PAGE_SIZE, GFP_KERNEL);
        if (!docg3->bbt)
                goto nochipfound;
        doc_reload_bbt(docg3);

        ret = mtd_device_parse_register(mtd, part_probes,
                                        NULL, NULL, 0);
        if (ret)
                goto register_error;

        doc_dbg_register(docg3);
        return 0;

register_error:
        kfree(docg3->bbt);
nochipfound:
        iounmap(docg3->base);
noress:
        kfree(mtd);
nomem2:
        kfree(docg3);
nomem1:
        return ret;
}

/**
 * docg3_release - Release the driver
 * @pdev: the platform device
 *
 * Returns 0
 */
static int __exit docg3_release(struct platform_device *pdev)
{
        struct mtd_info *mtd = platform_get_drvdata(pdev);
        struct docg3 *docg3 = mtd->priv;

        doc_dbg_unregister(docg3);
        mtd_device_unregister(mtd);
        iounmap(docg3->base);
        kfree(docg3->bbt);
        kfree(docg3);
        kfree(mtd);
        return 0;
}

static struct platform_driver g3_driver = {
        .driver         = {
                .name   = "docg3",
                .owner  = THIS_MODULE,
        },
        .remove         = __exit_p(docg3_release),
};

static int __init docg3_init(void)
{
        return platform_driver_probe(&g3_driver, docg3_probe);
}
module_init(docg3_init);


static void __exit docg3_exit(void)
{
        platform_driver_unregister(&g3_driver);
}
module_exit(docg3_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Robert Jarzmik <robert.jarzmik@free.fr>");
MODULE_DESCRIPTION("MTD driver for DiskOnChip G3");