/*
 * Copyright 2004-2008 Freescale Semiconductor, Inc.
 * Copyright 2009 Semihalf.
 *
 * Approved as OSADL project by a majority of OSADL members and funded
 * by OSADL membership fees in 2009;  for details see www.osadl.org.
 *
 * Based on original driver from Freescale Semiconductor
 * written by John Rigby <jrigby@freescale.com> on basis of mxc_nand.c.
 * Reworked and extended by Piotr Ziecik <kosmo@semihalf.com>.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 */

#include <linux/module.h>
#include <linux/clk.h>
#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.h>
#include <linux/mtd/partitions.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>

#include <asm/mpc5121.h>

/* Addresses for NFC MAIN RAM BUFFER areas */
#define NFC_MAIN_AREA(n)        ((n) *  0x200)

/* Addresses for NFC SPARE BUFFER areas */
#define NFC_SPARE_BUFFERS       8
#define NFC_SPARE_LEN           0x40
#define NFC_SPARE_AREA(n)       (0x1000 + ((n) * NFC_SPARE_LEN))

/* MPC5121 NFC registers */
#define NFC_BUF_ADDR            0x1E04
#define NFC_FLASH_ADDR          0x1E06
#define NFC_FLASH_CMD           0x1E08
#define NFC_CONFIG              0x1E0A
#define NFC_ECC_STATUS1         0x1E0C
#define NFC_ECC_STATUS2         0x1E0E
#define NFC_SPAS                0x1E10
#define NFC_WRPROT              0x1E12
#define NFC_NF_WRPRST           0x1E18
#define NFC_CONFIG1             0x1E1A
#define NFC_CONFIG2             0x1E1C
#define NFC_UNLOCKSTART_BLK0    0x1E20
#define NFC_UNLOCKEND_BLK0      0x1E22
#define NFC_UNLOCKSTART_BLK1    0x1E24
#define NFC_UNLOCKEND_BLK1      0x1E26
#define NFC_UNLOCKSTART_BLK2    0x1E28
#define NFC_UNLOCKEND_BLK2      0x1E2A
#define NFC_UNLOCKSTART_BLK3    0x1E2C
#define NFC_UNLOCKEND_BLK3      0x1E2E

/* Bit Definitions: NFC_BUF_ADDR */
#define NFC_RBA_MASK            (7 << 0)
#define NFC_ACTIVE_CS_SHIFT     5
#define NFC_ACTIVE_CS_MASK      (3 << NFC_ACTIVE_CS_SHIFT)

/* Bit Definitions: NFC_CONFIG */
#define NFC_BLS_UNLOCKED        (1 << 1)

/* Bit Definitions: NFC_CONFIG1 */
#define NFC_ECC_4BIT            (1 << 0)
#define NFC_FULL_PAGE_DMA       (1 << 1)
#define NFC_SPARE_ONLY          (1 << 2)
#define NFC_ECC_ENABLE          (1 << 3)
#define NFC_INT_MASK            (1 << 4)
#define NFC_BIG_ENDIAN          (1 << 5)
#define NFC_RESET               (1 << 6)
#define NFC_CE                  (1 << 7)
#define NFC_ONE_CYCLE           (1 << 8)
#define NFC_PPB_32              (0 << 9)
#define NFC_PPB_64              (1 << 9)
#define NFC_PPB_128             (2 << 9)
#define NFC_PPB_256             (3 << 9)
#define NFC_PPB_MASK            (3 << 9)
#define NFC_FULL_PAGE_INT       (1 << 11)

/* Bit Definitions: NFC_CONFIG2 */
#define NFC_COMMAND             (1 << 0)
#define NFC_ADDRESS             (1 << 1)
#define NFC_INPUT               (1 << 2)
#define NFC_OUTPUT              (1 << 3)
#define NFC_ID                  (1 << 4)
#define NFC_STATUS              (1 << 5)
#define NFC_CMD_FAIL            (1 << 15)
#define NFC_INT                 (1 << 15)

/* Bit Definitions: NFC_WRPROT */
#define NFC_WPC_LOCK_TIGHT      (1 << 0)
#define NFC_WPC_LOCK            (1 << 1)
#define NFC_WPC_UNLOCK          (1 << 2)

#define DRV_NAME                "mpc5121_nfc"

/* Timeouts */
#define NFC_RESET_TIMEOUT       1000            /* 1 ms */
#define NFC_TIMEOUT             (HZ / 10)       /* 1/10 s */

struct mpc5121_nfc_prv {
        struct nand_chip        chip;
        int                     irq;
        void __iomem            *regs;
        struct clk              *clk;
        wait_queue_head_t       irq_waitq;
        uint                    column;
        int                     spareonly;
        void __iomem            *csreg;
        struct device           *dev;
};

static void mpc5121_nfc_done(struct mtd_info *mtd);

/* Read NFC register */
static inline u16 nfc_read(struct mtd_info *mtd, uint reg)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);

        return in_be16(prv->regs + reg);
}

/* Write NFC register */
static inline void nfc_write(struct mtd_info *mtd, uint reg, u16 val)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);

        out_be16(prv->regs + reg, val);
}

/* Set bits in NFC register */
static inline void nfc_set(struct mtd_info *mtd, uint reg, u16 bits)
{
        nfc_write(mtd, reg, nfc_read(mtd, reg) | bits);
}

/* Clear bits in NFC register */
static inline void nfc_clear(struct mtd_info *mtd, uint reg, u16 bits)
{
        nfc_write(mtd, reg, nfc_read(mtd, reg) & ~bits);
}

/* Invoke address cycle */
static inline void mpc5121_nfc_send_addr(struct mtd_info *mtd, u16 addr)
{
        nfc_write(mtd, NFC_FLASH_ADDR, addr);
        nfc_write(mtd, NFC_CONFIG2, NFC_ADDRESS);
        mpc5121_nfc_done(mtd);
}

/* Invoke command cycle */
static inline void mpc5121_nfc_send_cmd(struct mtd_info *mtd, u16 cmd)
{
        nfc_write(mtd, NFC_FLASH_CMD, cmd);
        nfc_write(mtd, NFC_CONFIG2, NFC_COMMAND);
        mpc5121_nfc_done(mtd);
}

/* Send data from NFC buffers to NAND flash */
static inline void mpc5121_nfc_send_prog_page(struct mtd_info *mtd)
{
        nfc_clear(mtd, NFC_BUF_ADDR, NFC_RBA_MASK);
        nfc_write(mtd, NFC_CONFIG2, NFC_INPUT);
        mpc5121_nfc_done(mtd);
}

/* Receive data from NAND flash */
static inline void mpc5121_nfc_send_read_page(struct mtd_info *mtd)
{
        nfc_clear(mtd, NFC_BUF_ADDR, NFC_RBA_MASK);
        nfc_write(mtd, NFC_CONFIG2, NFC_OUTPUT);
        mpc5121_nfc_done(mtd);
}

/* Receive ID from NAND flash */
static inline void mpc5121_nfc_send_read_id(struct mtd_info *mtd)
{
        nfc_clear(mtd, NFC_BUF_ADDR, NFC_RBA_MASK);
        nfc_write(mtd, NFC_CONFIG2, NFC_ID);
        mpc5121_nfc_done(mtd);
}

/* Receive status from NAND flash */
static inline void mpc5121_nfc_send_read_status(struct mtd_info *mtd)
{
        nfc_clear(mtd, NFC_BUF_ADDR, NFC_RBA_MASK);
        nfc_write(mtd, NFC_CONFIG2, NFC_STATUS);
        mpc5121_nfc_done(mtd);
}

/* NFC interrupt handler */
static irqreturn_t mpc5121_nfc_irq(int irq, void *data)
{
        struct mtd_info *mtd = data;
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);

        nfc_set(mtd, NFC_CONFIG1, NFC_INT_MASK);
        wake_up(&prv->irq_waitq);

        return IRQ_HANDLED;
}

/* Wait for operation complete */
static void mpc5121_nfc_done(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);
        int rv;

        if ((nfc_read(mtd, NFC_CONFIG2) & NFC_INT) == 0) {
                nfc_clear(mtd, NFC_CONFIG1, NFC_INT_MASK);
                rv = wait_event_timeout(prv->irq_waitq,
                        (nfc_read(mtd, NFC_CONFIG2) & NFC_INT), NFC_TIMEOUT);

                if (!rv)
                        dev_warn(prv->dev,
                                "Timeout while waiting for interrupt.\n");
        }

        nfc_clear(mtd, NFC_CONFIG2, NFC_INT);
}

/* Do address cycle(s) */
static void mpc5121_nfc_addr_cycle(struct mtd_info *mtd, int column, int page)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        u32 pagemask = chip->pagemask;

        if (column != -1) {
                mpc5121_nfc_send_addr(mtd, column);
                if (mtd->writesize > 512)
                        mpc5121_nfc_send_addr(mtd, column >> 8);
        }

        if (page != -1) {
                do {
                        mpc5121_nfc_send_addr(mtd, page & 0xFF);
                        page >>= 8;
                        pagemask >>= 8;
                } while (pagemask);
        }
}

/* Control chip select signals */
static void mpc5121_nfc_select_chip(struct mtd_info *mtd, int chip)
{
        if (chip < 0) {
                nfc_clear(mtd, NFC_CONFIG1, NFC_CE);
                return;
        }

        nfc_clear(mtd, NFC_BUF_ADDR, NFC_ACTIVE_CS_MASK);
        nfc_set(mtd, NFC_BUF_ADDR, (chip << NFC_ACTIVE_CS_SHIFT) &
                                                        NFC_ACTIVE_CS_MASK);
        nfc_set(mtd, NFC_CONFIG1, NFC_CE);
}

/* Init external chip select logic on ADS5121 board */
static int ads5121_chipselect_init(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);
        struct device_node *dn;

        dn = of_find_compatible_node(NULL, NULL, "fsl,mpc5121ads-cpld");
        if (dn) {
                prv->csreg = of_iomap(dn, 0);
                of_node_put(dn);
                if (!prv->csreg)
                        return -ENOMEM;

                /* CPLD Register 9 controls NAND /CE Lines */
                prv->csreg += 9;
                return 0;
        }

        return -EINVAL;
}

/* Control chips select signal on ADS5121 board */
static void ads5121_select_chip(struct mtd_info *mtd, int chip)
{
        struct nand_chip *nand = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(nand);
        u8 v;

        v = in_8(prv->csreg);
        v |= 0x0F;

        if (chip >= 0) {
                mpc5121_nfc_select_chip(mtd, 0);
                v &= ~(1 << chip);
        } else
                mpc5121_nfc_select_chip(mtd, -1);

        out_8(prv->csreg, v);
}

/* Read NAND Ready/Busy signal */
static int mpc5121_nfc_dev_ready(struct mtd_info *mtd)
{
        /*
         * NFC handles ready/busy signal internally. Therefore, this function
         * always returns status as ready.
         */
        return 1;
}

/* Write command to NAND flash */
static void mpc5121_nfc_command(struct mtd_info *mtd, unsigned command,
                                                        int column, int page)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);

        prv->column = (column >= 0) ? column : 0;
        prv->spareonly = 0;

        switch (command) {
        case NAND_CMD_PAGEPROG:
                mpc5121_nfc_send_prog_page(mtd);
                break;
        /*
         * NFC does not support sub-page reads and writes,
         * so emulate them using full page transfers.
         */
        case NAND_CMD_READ0:
                column = 0;
                break;

        case NAND_CMD_READ1:
                prv->column += 256;
                command = NAND_CMD_READ0;
                column = 0;
                break;

        case NAND_CMD_READOOB:
                prv->spareonly = 1;
                command = NAND_CMD_READ0;
                column = 0;
                break;

        case NAND_CMD_SEQIN:
                mpc5121_nfc_command(mtd, NAND_CMD_READ0, column, page);
                column = 0;
                break;

        case NAND_CMD_ERASE1:
        case NAND_CMD_ERASE2:
        case NAND_CMD_READID:
        case NAND_CMD_STATUS:
                break;

        default:
                return;
        }

        mpc5121_nfc_send_cmd(mtd, command);
        mpc5121_nfc_addr_cycle(mtd, column, page);

        switch (command) {
        case NAND_CMD_READ0:
                if (mtd->writesize > 512)
                        mpc5121_nfc_send_cmd(mtd, NAND_CMD_READSTART);
                mpc5121_nfc_send_read_page(mtd);
                break;

        case NAND_CMD_READID:
                mpc5121_nfc_send_read_id(mtd);
                break;

        case NAND_CMD_STATUS:
                mpc5121_nfc_send_read_status(mtd);
                if (chip->options & NAND_BUSWIDTH_16)
                        prv->column = 1;
                else
                        prv->column = 0;
                break;
        }
}

/* Copy data from/to NFC spare buffers. */
static void mpc5121_nfc_copy_spare(struct mtd_info *mtd, uint offset,
                                                u8 *buffer, uint size, int wr)
{
        struct nand_chip *nand = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(nand);
        uint o, s, sbsize, blksize;

        /*
         * NAND spare area is available through NFC spare buffers.
         * The NFC divides spare area into (page_size / 512) chunks.
         * Each chunk is placed into separate spare memory area, using
         * first (spare_size / num_of_chunks) bytes of the buffer.
         *
         * For NAND device in which the spare area is not divided fully
         * by the number of chunks, number of used bytes in each spare
         * buffer is rounded down to the nearest even number of bytes,
         * and all remaining bytes are added to the last used spare area.
         *
         * For more information read section 26.6.10 of MPC5121e
         * Microcontroller Reference Manual, Rev. 3.
         */

        /* Calculate number of valid bytes in each spare buffer */
        sbsize = (mtd->oobsize / (mtd->writesize / 512)) & ~1;

        while (size) {
                /* Calculate spare buffer number */
                s = offset / sbsize;
                if (s > NFC_SPARE_BUFFERS - 1)
                        s = NFC_SPARE_BUFFERS - 1;

                /*
                 * Calculate offset to requested data block in selected spare
                 * buffer and its size.
                 */
                o = offset - (s * sbsize);
                blksize = min(sbsize - o, size);

                if (wr)
                        memcpy_toio(prv->regs + NFC_SPARE_AREA(s) + o,
                                                        buffer, blksize);
                else
                        memcpy_fromio(buffer,
                                prv->regs + NFC_SPARE_AREA(s) + o, blksize);

                buffer += blksize;
                offset += blksize;
                size -= blksize;
        };
}

/* Copy data from/to NFC main and spare buffers */
static void mpc5121_nfc_buf_copy(struct mtd_info *mtd, u_char *buf, int len,
                                                                        int wr)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);
        uint c = prv->column;
        uint l;

        /* Handle spare area access */
        if (prv->spareonly || c >= mtd->writesize) {
                /* Calculate offset from beginning of spare area */
                if (c >= mtd->writesize)
                        c -= mtd->writesize;

                prv->column += len;
                mpc5121_nfc_copy_spare(mtd, c, buf, len, wr);
                return;
        }

        /*
         * Handle main area access - limit copy length to prevent
         * crossing main/spare boundary.
         */
        l = min((uint)len, mtd->writesize - c);
        prv->column += l;

        if (wr)
                memcpy_toio(prv->regs + NFC_MAIN_AREA(0) + c, buf, l);
        else
                memcpy_fromio(buf, prv->regs + NFC_MAIN_AREA(0) + c, l);

        /* Handle crossing main/spare boundary */
        if (l != len) {
                buf += l;
                len -= l;
                mpc5121_nfc_buf_copy(mtd, buf, len, wr);
        }
}

/* Read data from NFC buffers */
static void mpc5121_nfc_read_buf(struct mtd_info *mtd, u_char *buf, int len)
{
        mpc5121_nfc_buf_copy(mtd, buf, len, 0);
}

/* Write data to NFC buffers */
static void mpc5121_nfc_write_buf(struct mtd_info *mtd,
                                                const u_char *buf, int len)
{
        mpc5121_nfc_buf_copy(mtd, (u_char *)buf, len, 1);
}

/* Read byte from NFC buffers */
static u8 mpc5121_nfc_read_byte(struct mtd_info *mtd)
{
        u8 tmp;

        mpc5121_nfc_read_buf(mtd, &tmp, sizeof(tmp));

        return tmp;
}

/* Read word from NFC buffers */
static u16 mpc5121_nfc_read_word(struct mtd_info *mtd)
{
        u16 tmp;

        mpc5121_nfc_read_buf(mtd, (u_char *)&tmp, sizeof(tmp));

        return tmp;
}

/*
 * Read NFC configuration from Reset Config Word
 *
 * NFC is configured during reset in basis of information stored
 * in Reset Config Word. There is no other way to set NAND block
 * size, spare size and bus width.
 */
static int mpc5121_nfc_read_hw_config(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);
        struct mpc512x_reset_module *rm;
        struct device_node *rmnode;
        uint rcw_pagesize = 0;
        uint rcw_sparesize = 0;
        uint rcw_width;
        uint rcwh;
        uint romloc, ps;
        int ret = 0;

        rmnode = of_find_compatible_node(NULL, NULL, "fsl,mpc5121-reset");
        if (!rmnode) {
                dev_err(prv->dev, "Missing 'fsl,mpc5121-reset' "
                                        "node in device tree!\n");
                return -ENODEV;
        }

        rm = of_iomap(rmnode, 0);
        if (!rm) {
                dev_err(prv->dev, "Error mapping reset module node!\n");
                ret = -EBUSY;
                goto out;
        }

        rcwh = in_be32(&rm->rcwhr);

        /* Bit 6: NFC bus width */
        rcw_width = ((rcwh >> 6) & 0x1) ? 2 : 1;

        /* Bit 7: NFC Page/Spare size */
        ps = (rcwh >> 7) & 0x1;

        /* Bits [22:21]: ROM Location */
        romloc = (rcwh >> 21) & 0x3;

        /* Decode RCW bits */
        switch ((ps << 2) | romloc) {
        case 0x00:
        case 0x01:
                rcw_pagesize = 512;
                rcw_sparesize = 16;
                break;
        case 0x02:
        case 0x03:
                rcw_pagesize = 4096;
                rcw_sparesize = 128;
                break;
        case 0x04:
        case 0x05:
                rcw_pagesize = 2048;
                rcw_sparesize = 64;
                break;
        case 0x06:
        case 0x07:
                rcw_pagesize = 4096;
                rcw_sparesize = 218;
                break;
        }

        mtd->writesize = rcw_pagesize;
        mtd->oobsize = rcw_sparesize;
        if (rcw_width == 2)
                chip->options |= NAND_BUSWIDTH_16;

        dev_notice(prv->dev, "Configured for "
                                "%u-bit NAND, page size %u "
                                "with %u spare.\n",
                                rcw_width * 8, rcw_pagesize,
                                rcw_sparesize);
        iounmap(rm);
out:
        of_node_put(rmnode);
        return ret;
}

/* Free driver resources */
static void mpc5121_nfc_free(struct device *dev, struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);

        if (prv->clk)
                clk_disable_unprepare(prv->clk);

        if (prv->csreg)
                iounmap(prv->csreg);
}

static int mpc5121_nfc_probe(struct platform_device *op)
{
        struct device_node *dn = op->dev.of_node;
        struct clk *clk;
        struct device *dev = &op->dev;
        struct mpc5121_nfc_prv *prv;
        struct resource res;
        struct mtd_info *mtd;
        struct nand_chip *chip;
        unsigned long regs_paddr, regs_size;
        const __be32 *chips_no;
        int resettime = 0;
        int retval = 0;
        int rev, len;

        /*
         * Check SoC revision. This driver supports only NFC
         * in MPC5121 revision 2 and MPC5123 revision 3.
         */
        rev = (mfspr(SPRN_SVR) >> 4) & 0xF;
        if ((rev != 2) && (rev != 3)) {
                dev_err(dev, "SoC revision %u is not supported!\n", rev);
                return -ENXIO;
        }

        prv = devm_kzalloc(dev, sizeof(*prv), GFP_KERNEL);
        if (!prv)
                return -ENOMEM;

        chip = &prv->chip;
        mtd = nand_to_mtd(chip);

        mtd->dev.parent = dev;
        nand_set_controller_data(chip, prv);
        nand_set_flash_node(chip, dn);
        prv->dev = dev;

        /* Read NFC configuration from Reset Config Word */
        retval = mpc5121_nfc_read_hw_config(mtd);
        if (retval) {
                dev_err(dev, "Unable to read NFC config!\n");
                return retval;
        }

        prv->irq = irq_of_parse_and_map(dn, 0);
        if (prv->irq == NO_IRQ) {
                dev_err(dev, "Error mapping IRQ!\n");
                return -EINVAL;
        }

        retval = of_address_to_resource(dn, 0, &res);
        if (retval) {
                dev_err(dev, "Error parsing memory region!\n");
                return retval;
        }

        chips_no = of_get_property(dn, "chips", &len);
        if (!chips_no || len != sizeof(*chips_no)) {
                dev_err(dev, "Invalid/missing 'chips' property!\n");
                return -EINVAL;
        }

        regs_paddr = res.start;
        regs_size = resource_size(&res);

        if (!devm_request_mem_region(dev, regs_paddr, regs_size, DRV_NAME)) {
                dev_err(dev, "Error requesting memory region!\n");
                return -EBUSY;
        }

        prv->regs = devm_ioremap(dev, regs_paddr, regs_size);
        if (!prv->regs) {
                dev_err(dev, "Error mapping memory region!\n");
                return -ENOMEM;
        }

        mtd->name = "MPC5121 NAND";
        chip->dev_ready = mpc5121_nfc_dev_ready;
        chip->cmdfunc = mpc5121_nfc_command;
        chip->read_byte = mpc5121_nfc_read_byte;
        chip->read_word = mpc5121_nfc_read_word;
        chip->read_buf = mpc5121_nfc_read_buf;
        chip->write_buf = mpc5121_nfc_write_buf;
        chip->select_chip = mpc5121_nfc_select_chip;
        chip->set_features      = nand_get_set_features_notsupp;
        chip->get_features      = nand_get_set_features_notsupp;
        chip->bbt_options = NAND_BBT_USE_FLASH;
        chip->ecc.mode = NAND_ECC_SOFT;
        chip->ecc.algo = NAND_ECC_HAMMING;

        /* Support external chip-select logic on ADS5121 board */
        if (of_machine_is_compatible("fsl,mpc5121ads")) {
                retval = ads5121_chipselect_init(mtd);
                if (retval) {
                        dev_err(dev, "Chipselect init error!\n");
                        return retval;
                }

                chip->select_chip = ads5121_select_chip;
        }

        /* Enable NFC clock */
        clk = devm_clk_get(dev, "ipg");
        if (IS_ERR(clk)) {
                dev_err(dev, "Unable to acquire NFC clock!\n");
                retval = PTR_ERR(clk);
                goto error;
        }
        retval = clk_prepare_enable(clk);
        if (retval) {
                dev_err(dev, "Unable to enable NFC clock!\n");
                goto error;
        }
        prv->clk = clk;

        /* Reset NAND Flash controller */
        nfc_set(mtd, NFC_CONFIG1, NFC_RESET);
        while (nfc_read(mtd, NFC_CONFIG1) & NFC_RESET) {
                if (resettime++ >= NFC_RESET_TIMEOUT) {
                        dev_err(dev, "Timeout while resetting NFC!\n");
                        retval = -EINVAL;
                        goto error;
                }

                udelay(1);
        }

        /* Enable write to NFC memory */
        nfc_write(mtd, NFC_CONFIG, NFC_BLS_UNLOCKED);

        /* Enable write to all NAND pages */
        nfc_write(mtd, NFC_UNLOCKSTART_BLK0, 0x0000);
        nfc_write(mtd, NFC_UNLOCKEND_BLK0, 0xFFFF);
        nfc_write(mtd, NFC_WRPROT, NFC_WPC_UNLOCK);

        /*
         * Setup NFC:
         *      - Big Endian transfers,
         *      - Interrupt after full page read/write.
         */
        nfc_write(mtd, NFC_CONFIG1, NFC_BIG_ENDIAN | NFC_INT_MASK |
                                                        NFC_FULL_PAGE_INT);

        /* Set spare area size */
        nfc_write(mtd, NFC_SPAS, mtd->oobsize >> 1);

        init_waitqueue_head(&prv->irq_waitq);
        retval = devm_request_irq(dev, prv->irq, &mpc5121_nfc_irq, 0, DRV_NAME,
                                                                        mtd);
        if (retval) {
                dev_err(dev, "Error requesting IRQ!\n");
                goto error;
        }

        /* Detect NAND chips */
        retval = nand_scan(mtd, be32_to_cpup(chips_no));
        if (retval) {
                dev_err(dev, "NAND Flash not found !\n");
                goto error;
        }

        /* Set erase block size */
        switch (mtd->erasesize / mtd->writesize) {
        case 32:
                nfc_set(mtd, NFC_CONFIG1, NFC_PPB_32);
                break;

        case 64:
                nfc_set(mtd, NFC_CONFIG1, NFC_PPB_64);
                break;

        case 128:
                nfc_set(mtd, NFC_CONFIG1, NFC_PPB_128);
                break;

        case 256:
                nfc_set(mtd, NFC_CONFIG1, NFC_PPB_256);
                break;

        default:
                dev_err(dev, "Unsupported NAND flash!\n");
                retval = -ENXIO;
                goto error;
        }

        dev_set_drvdata(dev, mtd);

        /* Register device in MTD */
        retval = mtd_device_register(mtd, NULL, 0);
        if (retval) {
                dev_err(dev, "Error adding MTD device!\n");
                goto error;
        }

        return 0;
error:
        mpc5121_nfc_free(dev, mtd);
        return retval;
}

static int mpc5121_nfc_remove(struct platform_device *op)
{
        struct device *dev = &op->dev;
        struct mtd_info *mtd = dev_get_drvdata(dev);

        nand_release(mtd);
        mpc5121_nfc_free(dev, mtd);

        return 0;
}

static const struct of_device_id mpc5121_nfc_match[] = {
        { .compatible = "fsl,mpc5121-nfc", },
        {},
};
MODULE_DEVICE_TABLE(of, mpc5121_nfc_match);

static struct platform_driver mpc5121_nfc_driver = {
        .probe          = mpc5121_nfc_probe,
        .remove         = mpc5121_nfc_remove,
        .driver         = {
                .name = DRV_NAME,
                .of_match_table = mpc5121_nfc_match,
        },
};

module_platform_driver(mpc5121_nfc_driver);

MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("MPC5121 NAND MTD driver");
MODULE_LICENSE("GPL");