/*
 * drivers/mtd/nand/fsmc_nand.c
 *
 * ST Microelectronics
 * Flexible Static Memory Controller (FSMC)
 * Driver for NAND portions
 *
 * Copyright © 2010 ST Microelectronics
 * Vipin Kumar <vipin.kumar@st.com>
 * Ashish Priyadarshi
 *
 * Based on drivers/mtd/nand/nomadik_nand.c
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/dmaengine.h>
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/resource.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/mtd/partitions.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/amba/bus.h>
#include <mtd/mtd-abi.h>

/* fsmc controller registers for NOR flash */
#define CTRL                    0x0
        /* ctrl register definitions */
        #define BANK_ENABLE             (1 << 0)
        #define MUXED                   (1 << 1)
        #define NOR_DEV                 (2 << 2)
        #define WIDTH_8                 (0 << 4)
        #define WIDTH_16                (1 << 4)
        #define RSTPWRDWN               (1 << 6)
        #define WPROT                   (1 << 7)
        #define WRT_ENABLE              (1 << 12)
        #define WAIT_ENB                (1 << 13)

#define CTRL_TIM                0x4
        /* ctrl_tim register definitions */

#define FSMC_NOR_BANK_SZ        0x8
#define FSMC_NOR_REG_SIZE       0x40

#define FSMC_NOR_REG(base, bank, reg)           (base + \
                                                FSMC_NOR_BANK_SZ * (bank) + \
                                                reg)

/* fsmc controller registers for NAND flash */
#define PC                      0x00
        /* pc register definitions */
        #define FSMC_RESET              (1 << 0)
        #define FSMC_WAITON             (1 << 1)
        #define FSMC_ENABLE             (1 << 2)
        #define FSMC_DEVTYPE_NAND       (1 << 3)
        #define FSMC_DEVWID_8           (0 << 4)
        #define FSMC_DEVWID_16          (1 << 4)
        #define FSMC_ECCEN              (1 << 6)
        #define FSMC_ECCPLEN_512        (0 << 7)
        #define FSMC_ECCPLEN_256        (1 << 7)
        #define FSMC_TCLR_1             (1)
        #define FSMC_TCLR_SHIFT         (9)
        #define FSMC_TCLR_MASK          (0xF)
        #define FSMC_TAR_1              (1)
        #define FSMC_TAR_SHIFT          (13)
        #define FSMC_TAR_MASK           (0xF)
#define STS                     0x04
        /* sts register definitions */
        #define FSMC_CODE_RDY           (1 << 15)
#define COMM                    0x08
        /* comm register definitions */
        #define FSMC_TSET_0             0
        #define FSMC_TSET_SHIFT         0
        #define FSMC_TSET_MASK          0xFF
        #define FSMC_TWAIT_6            6
        #define FSMC_TWAIT_SHIFT        8
        #define FSMC_TWAIT_MASK         0xFF
        #define FSMC_THOLD_4            4
        #define FSMC_THOLD_SHIFT        16
        #define FSMC_THOLD_MASK         0xFF
        #define FSMC_THIZ_1             1
        #define FSMC_THIZ_SHIFT         24
        #define FSMC_THIZ_MASK          0xFF
#define ATTRIB                  0x0C
#define IOATA                   0x10
#define ECC1                    0x14
#define ECC2                    0x18
#define ECC3                    0x1C
#define FSMC_NAND_BANK_SZ       0x20

#define FSMC_NAND_REG(base, bank, reg)          (base + FSMC_NOR_REG_SIZE + \
                                                (FSMC_NAND_BANK_SZ * (bank)) + \
                                                reg)

#define FSMC_BUSY_WAIT_TIMEOUT  (1 * HZ)

struct fsmc_nand_timings {
        uint8_t tclr;
        uint8_t tar;
        uint8_t thiz;
        uint8_t thold;
        uint8_t twait;
        uint8_t tset;
};

enum access_mode {
        USE_DMA_ACCESS = 1,
        USE_WORD_ACCESS,
};

/**
 * struct fsmc_nand_data - structure for FSMC NAND device state
 *
 * @pid:                Part ID on the AMBA PrimeCell format
 * @mtd:                MTD info for a NAND flash.
 * @nand:               Chip related info for a NAND flash.
 * @partitions:         Partition info for a NAND Flash.
 * @nr_partitions:      Total number of partition of a NAND flash.
 *
 * @bank:               Bank number for probed device.
 * @clk:                Clock structure for FSMC.
 *
 * @read_dma_chan:      DMA channel for read access
 * @write_dma_chan:     DMA channel for write access to NAND
 * @dma_access_complete: Completion structure
 *
 * @data_pa:            NAND Physical port for Data.
 * @data_va:            NAND port for Data.
 * @cmd_va:             NAND port for Command.
 * @addr_va:            NAND port for Address.
 * @regs_va:            FSMC regs base address.
 */
struct fsmc_nand_data {
        u32                     pid;
        struct nand_chip        nand;

        unsigned int            bank;
        struct device           *dev;
        enum access_mode        mode;
        struct clk              *clk;

        /* DMA related objects */
        struct dma_chan         *read_dma_chan;
        struct dma_chan         *write_dma_chan;
        struct completion       dma_access_complete;

        struct fsmc_nand_timings *dev_timings;

        dma_addr_t              data_pa;
        void __iomem            *data_va;
        void __iomem            *cmd_va;
        void __iomem            *addr_va;
        void __iomem            *regs_va;
};

static int fsmc_ecc1_ooblayout_ecc(struct mtd_info *mtd, int section,
                                   struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (section >= chip->ecc.steps)
                return -ERANGE;

        oobregion->offset = (section * 16) + 2;
        oobregion->length = 3;

        return 0;
}

static int fsmc_ecc1_ooblayout_free(struct mtd_info *mtd, int section,
                                    struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (section >= chip->ecc.steps)
                return -ERANGE;

        oobregion->offset = (section * 16) + 8;

        if (section < chip->ecc.steps - 1)
                oobregion->length = 8;
        else
                oobregion->length = mtd->oobsize - oobregion->offset;

        return 0;
}

static const struct mtd_ooblayout_ops fsmc_ecc1_ooblayout_ops = {
        .ecc = fsmc_ecc1_ooblayout_ecc,
        .free = fsmc_ecc1_ooblayout_free,
};

/*
 * ECC placement definitions in oobfree type format.
 * There are 13 bytes of ecc for every 512 byte block and it has to be read
 * consecutively and immediately after the 512 byte data block for hardware to
 * generate the error bit offsets in 512 byte data.
 */
static int fsmc_ecc4_ooblayout_ecc(struct mtd_info *mtd, int section,
                                   struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (section >= chip->ecc.steps)
                return -ERANGE;

        oobregion->length = chip->ecc.bytes;

        if (!section && mtd->writesize <= 512)
                oobregion->offset = 0;
        else
                oobregion->offset = (section * 16) + 2;

        return 0;
}

static int fsmc_ecc4_ooblayout_free(struct mtd_info *mtd, int section,
                                    struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (section >= chip->ecc.steps)
                return -ERANGE;

        oobregion->offset = (section * 16) + 15;

        if (section < chip->ecc.steps - 1)
                oobregion->length = 3;
        else
                oobregion->length = mtd->oobsize - oobregion->offset;

        return 0;
}

static const struct mtd_ooblayout_ops fsmc_ecc4_ooblayout_ops = {
        .ecc = fsmc_ecc4_ooblayout_ecc,
        .free = fsmc_ecc4_ooblayout_free,
};

static inline struct fsmc_nand_data *mtd_to_fsmc(struct mtd_info *mtd)
{
        return container_of(mtd_to_nand(mtd), struct fsmc_nand_data, nand);
}

/*
 * fsmc_cmd_ctrl - For facilitaing Hardware access
 * This routine allows hardware specific access to control-lines(ALE,CLE)
 */
static void fsmc_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        struct fsmc_nand_data *host = mtd_to_fsmc(mtd);
        void __iomem *regs = host->regs_va;
        unsigned int bank = host->bank;

        if (ctrl & NAND_CTRL_CHANGE) {
                u32 pc;

                if (ctrl & NAND_CLE) {
                        this->IO_ADDR_R = host->cmd_va;
                        this->IO_ADDR_W = host->cmd_va;
                } else if (ctrl & NAND_ALE) {
                        this->IO_ADDR_R = host->addr_va;
                        this->IO_ADDR_W = host->addr_va;
                } else {
                        this->IO_ADDR_R = host->data_va;
                        this->IO_ADDR_W = host->data_va;
                }

                pc = readl(FSMC_NAND_REG(regs, bank, PC));
                if (ctrl & NAND_NCE)
                        pc |= FSMC_ENABLE;
                else
                        pc &= ~FSMC_ENABLE;
                writel_relaxed(pc, FSMC_NAND_REG(regs, bank, PC));
        }

        mb();

        if (cmd != NAND_CMD_NONE)
                writeb_relaxed(cmd, this->IO_ADDR_W);
}

/*
 * fsmc_nand_setup - FSMC (Flexible Static Memory Controller) init routine
 *
 * This routine initializes timing parameters related to NAND memory access in
 * FSMC registers
 */
static void fsmc_nand_setup(struct fsmc_nand_data *host,
                            struct fsmc_nand_timings *tims)
{
        uint32_t value = FSMC_DEVTYPE_NAND | FSMC_ENABLE | FSMC_WAITON;
        uint32_t tclr, tar, thiz, thold, twait, tset;
        unsigned int bank = host->bank;
        void __iomem *regs = host->regs_va;

        tclr = (tims->tclr & FSMC_TCLR_MASK) << FSMC_TCLR_SHIFT;
        tar = (tims->tar & FSMC_TAR_MASK) << FSMC_TAR_SHIFT;
        thiz = (tims->thiz & FSMC_THIZ_MASK) << FSMC_THIZ_SHIFT;
        thold = (tims->thold & FSMC_THOLD_MASK) << FSMC_THOLD_SHIFT;
        twait = (tims->twait & FSMC_TWAIT_MASK) << FSMC_TWAIT_SHIFT;
        tset = (tims->tset & FSMC_TSET_MASK) << FSMC_TSET_SHIFT;

        if (host->nand.options & NAND_BUSWIDTH_16)
                writel_relaxed(value | FSMC_DEVWID_16,
                                FSMC_NAND_REG(regs, bank, PC));
        else
                writel_relaxed(value | FSMC_DEVWID_8,
                                FSMC_NAND_REG(regs, bank, PC));

        writel_relaxed(readl(FSMC_NAND_REG(regs, bank, PC)) | tclr | tar,
                        FSMC_NAND_REG(regs, bank, PC));
        writel_relaxed(thiz | thold | twait | tset,
                        FSMC_NAND_REG(regs, bank, COMM));
        writel_relaxed(thiz | thold | twait | tset,
                        FSMC_NAND_REG(regs, bank, ATTRIB));
}

static int fsmc_calc_timings(struct fsmc_nand_data *host,
                             const struct nand_sdr_timings *sdrt,
                             struct fsmc_nand_timings *tims)
{
        unsigned long hclk = clk_get_rate(host->clk);
        unsigned long hclkn = NSEC_PER_SEC / hclk;
        uint32_t thiz, thold, twait, tset;

        if (sdrt->tRC_min < 30000)
                return -EOPNOTSUPP;

        tims->tar = DIV_ROUND_UP(sdrt->tAR_min / 1000, hclkn) - 1;
        if (tims->tar > FSMC_TAR_MASK)
                tims->tar = FSMC_TAR_MASK;
        tims->tclr = DIV_ROUND_UP(sdrt->tCLR_min / 1000, hclkn) - 1;
        if (tims->tclr > FSMC_TCLR_MASK)
                tims->tclr = FSMC_TCLR_MASK;

        thiz = sdrt->tCS_min - sdrt->tWP_min;
        tims->thiz = DIV_ROUND_UP(thiz / 1000, hclkn);

        thold = sdrt->tDH_min;
        if (thold < sdrt->tCH_min)
                thold = sdrt->tCH_min;
        if (thold < sdrt->tCLH_min)
                thold = sdrt->tCLH_min;
        if (thold < sdrt->tWH_min)
                thold = sdrt->tWH_min;
        if (thold < sdrt->tALH_min)
                thold = sdrt->tALH_min;
        if (thold < sdrt->tREH_min)
                thold = sdrt->tREH_min;
        tims->thold = DIV_ROUND_UP(thold / 1000, hclkn);
        if (tims->thold == 0)
                tims->thold = 1;
        else if (tims->thold > FSMC_THOLD_MASK)
                tims->thold = FSMC_THOLD_MASK;

        twait = max(sdrt->tRP_min, sdrt->tWP_min);
        tims->twait = DIV_ROUND_UP(twait / 1000, hclkn) - 1;
        if (tims->twait == 0)
                tims->twait = 1;
        else if (tims->twait > FSMC_TWAIT_MASK)
                tims->twait = FSMC_TWAIT_MASK;

        tset = max(sdrt->tCS_min - sdrt->tWP_min,
                   sdrt->tCEA_max - sdrt->tREA_max);
        tims->tset = DIV_ROUND_UP(tset / 1000, hclkn) - 1;
        if (tims->tset == 0)
                tims->tset = 1;
        else if (tims->tset > FSMC_TSET_MASK)
                tims->tset = FSMC_TSET_MASK;

        return 0;
}

static int fsmc_setup_data_interface(struct mtd_info *mtd, int csline,
                                     const struct nand_data_interface *conf)
{
        struct nand_chip *nand = mtd_to_nand(mtd);
        struct fsmc_nand_data *host = nand_get_controller_data(nand);
        struct fsmc_nand_timings tims;
        const struct nand_sdr_timings *sdrt;
        int ret;

        sdrt = nand_get_sdr_timings(conf);
        if (IS_ERR(sdrt))
                return PTR_ERR(sdrt);

        ret = fsmc_calc_timings(host, sdrt, &tims);
        if (ret)
                return ret;

        if (csline == NAND_DATA_IFACE_CHECK_ONLY)
                return 0;

        fsmc_nand_setup(host, &tims);

        return 0;
}

/*
 * fsmc_enable_hwecc - Enables Hardware ECC through FSMC registers
 */
static void fsmc_enable_hwecc(struct mtd_info *mtd, int mode)
{
        struct fsmc_nand_data *host = mtd_to_fsmc(mtd);
        void __iomem *regs = host->regs_va;
        uint32_t bank = host->bank;

        writel_relaxed(readl(FSMC_NAND_REG(regs, bank, PC)) & ~FSMC_ECCPLEN_256,
                        FSMC_NAND_REG(regs, bank, PC));
        writel_relaxed(readl(FSMC_NAND_REG(regs, bank, PC)) & ~FSMC_ECCEN,
                        FSMC_NAND_REG(regs, bank, PC));
        writel_relaxed(readl(FSMC_NAND_REG(regs, bank, PC)) | FSMC_ECCEN,
                        FSMC_NAND_REG(regs, bank, PC));
}

/*
 * fsmc_read_hwecc_ecc4 - Hardware ECC calculator for ecc4 option supported by
 * FSMC. ECC is 13 bytes for 512 bytes of data (supports error correction up to
 * max of 8-bits)
 */
static int fsmc_read_hwecc_ecc4(struct mtd_info *mtd, const uint8_t *data,
                                uint8_t *ecc)
{
        struct fsmc_nand_data *host = mtd_to_fsmc(mtd);
        void __iomem *regs = host->regs_va;
        uint32_t bank = host->bank;
        uint32_t ecc_tmp;
        unsigned long deadline = jiffies + FSMC_BUSY_WAIT_TIMEOUT;

        do {
                if (readl_relaxed(FSMC_NAND_REG(regs, bank, STS)) & FSMC_CODE_RDY)
                        break;
                else
                        cond_resched();
        } while (!time_after_eq(jiffies, deadline));

        if (time_after_eq(jiffies, deadline)) {
                dev_err(host->dev, "calculate ecc timed out\n");
                return -ETIMEDOUT;
        }

        ecc_tmp = readl_relaxed(FSMC_NAND_REG(regs, bank, ECC1));
        ecc[0] = (uint8_t) (ecc_tmp >> 0);
        ecc[1] = (uint8_t) (ecc_tmp >> 8);
        ecc[2] = (uint8_t) (ecc_tmp >> 16);
        ecc[3] = (uint8_t) (ecc_tmp >> 24);

        ecc_tmp = readl_relaxed(FSMC_NAND_REG(regs, bank, ECC2));
        ecc[4] = (uint8_t) (ecc_tmp >> 0);
        ecc[5] = (uint8_t) (ecc_tmp >> 8);
        ecc[6] = (uint8_t) (ecc_tmp >> 16);
        ecc[7] = (uint8_t) (ecc_tmp >> 24);

        ecc_tmp = readl_relaxed(FSMC_NAND_REG(regs, bank, ECC3));
        ecc[8] = (uint8_t) (ecc_tmp >> 0);
        ecc[9] = (uint8_t) (ecc_tmp >> 8);
        ecc[10] = (uint8_t) (ecc_tmp >> 16);
        ecc[11] = (uint8_t) (ecc_tmp >> 24);

        ecc_tmp = readl_relaxed(FSMC_NAND_REG(regs, bank, STS));
        ecc[12] = (uint8_t) (ecc_tmp >> 16);

        return 0;
}

/*
 * fsmc_read_hwecc_ecc1 - Hardware ECC calculator for ecc1 option supported by
 * FSMC. ECC is 3 bytes for 512 bytes of data (supports error correction up to
 * max of 1-bit)
 */
static int fsmc_read_hwecc_ecc1(struct mtd_info *mtd, const uint8_t *data,
                                uint8_t *ecc)
{
        struct fsmc_nand_data *host = mtd_to_fsmc(mtd);
        void __iomem *regs = host->regs_va;
        uint32_t bank = host->bank;
        uint32_t ecc_tmp;

        ecc_tmp = readl_relaxed(FSMC_NAND_REG(regs, bank, ECC1));
        ecc[0] = (uint8_t) (ecc_tmp >> 0);
        ecc[1] = (uint8_t) (ecc_tmp >> 8);
        ecc[2] = (uint8_t) (ecc_tmp >> 16);

        return 0;
}

/* Count the number of 0's in buff upto a max of max_bits */
static int count_written_bits(uint8_t *buff, int size, int max_bits)
{
        int k, written_bits = 0;

        for (k = 0; k < size; k++) {
                written_bits += hweight8(~buff[k]);
                if (written_bits > max_bits)
                        break;
        }

        return written_bits;
}

static void dma_complete(void *param)
{
        struct fsmc_nand_data *host = param;

        complete(&host->dma_access_complete);
}

static int dma_xfer(struct fsmc_nand_data *host, void *buffer, int len,
                enum dma_data_direction direction)
{
        struct dma_chan *chan;
        struct dma_device *dma_dev;
        struct dma_async_tx_descriptor *tx;
        dma_addr_t dma_dst, dma_src, dma_addr;
        dma_cookie_t cookie;
        unsigned long flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
        int ret;
        unsigned long time_left;

        if (direction == DMA_TO_DEVICE)
                chan = host->write_dma_chan;
        else if (direction == DMA_FROM_DEVICE)
                chan = host->read_dma_chan;
        else
                return -EINVAL;

        dma_dev = chan->device;
        dma_addr = dma_map_single(dma_dev->dev, buffer, len, direction);

        if (direction == DMA_TO_DEVICE) {
                dma_src = dma_addr;
                dma_dst = host->data_pa;
        } else {
                dma_src = host->data_pa;
                dma_dst = dma_addr;
        }

        tx = dma_dev->device_prep_dma_memcpy(chan, dma_dst, dma_src,
                        len, flags);
        if (!tx) {
                dev_err(host->dev, "device_prep_dma_memcpy error\n");
                ret = -EIO;
                goto unmap_dma;
        }

        tx->callback = dma_complete;
        tx->callback_param = host;
        cookie = tx->tx_submit(tx);

        ret = dma_submit_error(cookie);
        if (ret) {
                dev_err(host->dev, "dma_submit_error %d\n", cookie);
                goto unmap_dma;
        }

        dma_async_issue_pending(chan);

        time_left =
        wait_for_completion_timeout(&host->dma_access_complete,
                                msecs_to_jiffies(3000));
        if (time_left == 0) {
                dmaengine_terminate_all(chan);
                dev_err(host->dev, "wait_for_completion_timeout\n");
                ret = -ETIMEDOUT;
                goto unmap_dma;
        }

        ret = 0;

unmap_dma:
        dma_unmap_single(dma_dev->dev, dma_addr, len, direction);

        return ret;
}

/*
 * fsmc_write_buf - write buffer to chip
 * @mtd:        MTD device structure
 * @buf:        data buffer
 * @len:        number of bytes to write
 */
static void fsmc_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
{
        int i;
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (IS_ALIGNED((uint32_t)buf, sizeof(uint32_t)) &&
                        IS_ALIGNED(len, sizeof(uint32_t))) {
                uint32_t *p = (uint32_t *)buf;
                len = len >> 2;
                for (i = 0; i < len; i++)
                        writel_relaxed(p[i], chip->IO_ADDR_W);
        } else {
                for (i = 0; i < len; i++)
                        writeb_relaxed(buf[i], chip->IO_ADDR_W);
        }
}

/*
 * fsmc_read_buf - read chip data into buffer
 * @mtd:        MTD device structure
 * @buf:        buffer to store date
 * @len:        number of bytes to read
 */
static void fsmc_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
        int i;
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (IS_ALIGNED((uint32_t)buf, sizeof(uint32_t)) &&
                        IS_ALIGNED(len, sizeof(uint32_t))) {
                uint32_t *p = (uint32_t *)buf;
                len = len >> 2;
                for (i = 0; i < len; i++)
                        p[i] = readl_relaxed(chip->IO_ADDR_R);
        } else {
                for (i = 0; i < len; i++)
                        buf[i] = readb_relaxed(chip->IO_ADDR_R);
        }
}

/*
 * fsmc_read_buf_dma - read chip data into buffer
 * @mtd:        MTD device structure
 * @buf:        buffer to store date
 * @len:        number of bytes to read
 */
static void fsmc_read_buf_dma(struct mtd_info *mtd, uint8_t *buf, int len)
{
        struct fsmc_nand_data *host  = mtd_to_fsmc(mtd);

        dma_xfer(host, buf, len, DMA_FROM_DEVICE);
}

/*
 * fsmc_write_buf_dma - write buffer to chip
 * @mtd:        MTD device structure
 * @buf:        data buffer
 * @len:        number of bytes to write
 */
static void fsmc_write_buf_dma(struct mtd_info *mtd, const uint8_t *buf,
                int len)
{
        struct fsmc_nand_data *host = mtd_to_fsmc(mtd);

        dma_xfer(host, (void *)buf, len, DMA_TO_DEVICE);
}

/*
 * fsmc_read_page_hwecc
 * @mtd:        mtd info structure
 * @chip:       nand chip info structure
 * @buf:        buffer to store read data
 * @oob_required:       caller expects OOB data read to chip->oob_poi
 * @page:       page number to read
 *
 * This routine is needed for fsmc version 8 as reading from NAND chip has to be
 * performed in a strict sequence as follows:
 * data(512 byte) -> ecc(13 byte)
 * After this read, fsmc hardware generates and reports error data bits(up to a
 * max of 8 bits)
 */
static int fsmc_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
                                 uint8_t *buf, int oob_required, int page)
{
        int i, j, s, stat, eccsize = chip->ecc.size;
        int eccbytes = chip->ecc.bytes;
        int eccsteps = chip->ecc.steps;
        uint8_t *p = buf;
        uint8_t *ecc_calc = chip->ecc.calc_buf;
        uint8_t *ecc_code = chip->ecc.code_buf;
        int off, len, group = 0;
        /*
         * ecc_oob is intentionally taken as uint16_t. In 16bit devices, we
         * end up reading 14 bytes (7 words) from oob. The local array is
         * to maintain word alignment
         */
        uint16_t ecc_oob[7];
        uint8_t *oob = (uint8_t *)&ecc_oob[0];
        unsigned int max_bitflips = 0;

        for (i = 0, s = 0; s < eccsteps; s++, i += eccbytes, p += eccsize) {
                nand_read_page_op(chip, page, s * eccsize, NULL, 0);
                chip->ecc.hwctl(mtd, NAND_ECC_READ);
                chip->read_buf(mtd, p, eccsize);

                for (j = 0; j < eccbytes;) {
                        struct mtd_oob_region oobregion;
                        int ret;

                        ret = mtd_ooblayout_ecc(mtd, group++, &oobregion);
                        if (ret)
                                return ret;

                        off = oobregion.offset;
                        len = oobregion.length;

                        /*
                         * length is intentionally kept a higher multiple of 2
                         * to read at least 13 bytes even in case of 16 bit NAND
                         * devices
                         */
                        if (chip->options & NAND_BUSWIDTH_16)
                                len = roundup(len, 2);

                        nand_read_oob_op(chip, page, off, oob + j, len);
                        j += len;
                }

                memcpy(&ecc_code[i], oob, chip->ecc.bytes);
                chip->ecc.calculate(mtd, p, &ecc_calc[i]);

                stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
                if (stat < 0) {
                        mtd->ecc_stats.failed++;
                } else {
                        mtd->ecc_stats.corrected += stat;
                        max_bitflips = max_t(unsigned int, max_bitflips, stat);
                }
        }

        return max_bitflips;
}

/*
 * fsmc_bch8_correct_data
 * @mtd:        mtd info structure
 * @dat:        buffer of read data
 * @read_ecc:   ecc read from device spare area
 * @calc_ecc:   ecc calculated from read data
 *
 * calc_ecc is a 104 bit information containing maximum of 8 error
 * offset informations of 13 bits each in 512 bytes of read data.
 */
static int fsmc_bch8_correct_data(struct mtd_info *mtd, uint8_t *dat,
                             uint8_t *read_ecc, uint8_t *calc_ecc)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct fsmc_nand_data *host = mtd_to_fsmc(mtd);
        void __iomem *regs = host->regs_va;
        unsigned int bank = host->bank;
        uint32_t err_idx[8];
        uint32_t num_err, i;
        uint32_t ecc1, ecc2, ecc3, ecc4;

        num_err = (readl_relaxed(FSMC_NAND_REG(regs, bank, STS)) >> 10) & 0xF;

        /* no bit flipping */
        if (likely(num_err == 0))
                return 0;

        /* too many errors */
        if (unlikely(num_err > 8)) {
                /*
                 * This is a temporary erase check. A newly erased page read
                 * would result in an ecc error because the oob data is also
                 * erased to FF and the calculated ecc for an FF data is not
                 * FF..FF.
                 * This is a workaround to skip performing correction in case
                 * data is FF..FF
                 *
                 * Logic:
                 * For every page, each bit written as 0 is counted until these
                 * number of bits are greater than 8 (the maximum correction
                 * capability of FSMC for each 512 + 13 bytes)
                 */

                int bits_ecc = count_written_bits(read_ecc, chip->ecc.bytes, 8);
                int bits_data = count_written_bits(dat, chip->ecc.size, 8);

                if ((bits_ecc + bits_data) <= 8) {
                        if (bits_data)
                                memset(dat, 0xff, chip->ecc.size);
                        return bits_data;
                }

                return -EBADMSG;
        }

        /*
         * ------------------- calc_ecc[] bit wise -----------|--13 bits--|
         * |---idx[7]--|--.....-----|---idx[2]--||---idx[1]--||---idx[0]--|
         *
         * calc_ecc is a 104 bit information containing maximum of 8 error
         * offset informations of 13 bits each. calc_ecc is copied into a
         * uint64_t array and error offset indexes are populated in err_idx
         * array
         */
        ecc1 = readl_relaxed(FSMC_NAND_REG(regs, bank, ECC1));
        ecc2 = readl_relaxed(FSMC_NAND_REG(regs, bank, ECC2));
        ecc3 = readl_relaxed(FSMC_NAND_REG(regs, bank, ECC3));
        ecc4 = readl_relaxed(FSMC_NAND_REG(regs, bank, STS));

        err_idx[0] = (ecc1 >> 0) & 0x1FFF;
        err_idx[1] = (ecc1 >> 13) & 0x1FFF;
        err_idx[2] = (((ecc2 >> 0) & 0x7F) << 6) | ((ecc1 >> 26) & 0x3F);
        err_idx[3] = (ecc2 >> 7) & 0x1FFF;
        err_idx[4] = (((ecc3 >> 0) & 0x1) << 12) | ((ecc2 >> 20) & 0xFFF);
        err_idx[5] = (ecc3 >> 1) & 0x1FFF;
        err_idx[6] = (ecc3 >> 14) & 0x1FFF;
        err_idx[7] = (((ecc4 >> 16) & 0xFF) << 5) | ((ecc3 >> 27) & 0x1F);

        i = 0;
        while (num_err--) {
                change_bit(0, (unsigned long *)&err_idx[i]);
                change_bit(1, (unsigned long *)&err_idx[i]);

                if (err_idx[i] < chip->ecc.size * 8) {
                        change_bit(err_idx[i], (unsigned long *)dat);
                        i++;
                }
        }
        return i;
}

static bool filter(struct dma_chan *chan, void *slave)
{
        chan->private = slave;
        return true;
}

static int fsmc_nand_probe_config_dt(struct platform_device *pdev,
                                     struct fsmc_nand_data *host,
                                     struct nand_chip *nand)
{
        struct device_node *np = pdev->dev.of_node;
        u32 val;
        int ret;

        nand->options = 0;

        if (!of_property_read_u32(np, "bank-width", &val)) {
                if (val == 2) {
                        nand->options |= NAND_BUSWIDTH_16;
                } else if (val != 1) {
                        dev_err(&pdev->dev, "invalid bank-width %u\n", val);
                        return -EINVAL;
                }
        }

        if (of_get_property(np, "nand-skip-bbtscan", NULL))
                nand->options |= NAND_SKIP_BBTSCAN;

        host->dev_timings = devm_kzalloc(&pdev->dev,
                                sizeof(*host->dev_timings), GFP_KERNEL);
        if (!host->dev_timings)
                return -ENOMEM;
        ret = of_property_read_u8_array(np, "timings", (u8 *)host->dev_timings,
                                                sizeof(*host->dev_timings));
        if (ret)
                host->dev_timings = NULL;

        /* Set default NAND bank to 0 */
        host->bank = 0;
        if (!of_property_read_u32(np, "bank", &val)) {
                if (val > 3) {
                        dev_err(&pdev->dev, "invalid bank %u\n", val);
                        return -EINVAL;
                }
                host->bank = val;
        }
        return 0;
}

/*
 * fsmc_nand_probe - Probe function
 * @pdev:       platform device structure
 */
static int __init fsmc_nand_probe(struct platform_device *pdev)
{
        struct fsmc_nand_data *host;
        struct mtd_info *mtd;
        struct nand_chip *nand;
        struct resource *res;
        dma_cap_mask_t mask;
        int ret = 0;
        u32 pid;
        int i;

        /* Allocate memory for the device structure (and zero it) */
        host = devm_kzalloc(&pdev->dev, sizeof(*host), GFP_KERNEL);
        if (!host)
                return -ENOMEM;

        nand = &host->nand;

        ret = fsmc_nand_probe_config_dt(pdev, host, nand);
        if (ret)
                return ret;

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "nand_data");
        host->data_va = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(host->data_va))
                return PTR_ERR(host->data_va);

        host->data_pa = (dma_addr_t)res->start;

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "nand_addr");
        host->addr_va = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(host->addr_va))
                return PTR_ERR(host->addr_va);

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "nand_cmd");
        host->cmd_va = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(host->cmd_va))
                return PTR_ERR(host->cmd_va);

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "fsmc_regs");
        host->regs_va = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(host->regs_va))
                return PTR_ERR(host->regs_va);

        host->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(host->clk)) {
                dev_err(&pdev->dev, "failed to fetch block clock\n");
                return PTR_ERR(host->clk);
        }

        ret = clk_prepare_enable(host->clk);
        if (ret)
                return ret;

        /*
         * This device ID is actually a common AMBA ID as used on the
         * AMBA PrimeCell bus. However it is not a PrimeCell.
         */
        for (pid = 0, i = 0; i < 4; i++)
                pid |= (readl(host->regs_va + resource_size(res) - 0x20 + 4 * i) & 255) << (i * 8);
        host->pid = pid;
        dev_info(&pdev->dev, "FSMC device partno %03x, manufacturer %02x, "
                 "revision %02x, config %02x\n",
                 AMBA_PART_BITS(pid), AMBA_MANF_BITS(pid),
                 AMBA_REV_BITS(pid), AMBA_CONFIG_BITS(pid));

        host->dev = &pdev->dev;

        if (host->mode == USE_DMA_ACCESS)
                init_completion(&host->dma_access_complete);

        /* Link all private pointers */
        mtd = nand_to_mtd(&host->nand);
        nand_set_controller_data(nand, host);
        nand_set_flash_node(nand, pdev->dev.of_node);

        mtd->dev.parent = &pdev->dev;
        nand->IO_ADDR_R = host->data_va;
        nand->IO_ADDR_W = host->data_va;
        nand->cmd_ctrl = fsmc_cmd_ctrl;
        nand->chip_delay = 30;

        /*
         * Setup default ECC mode. nand_dt_init() called from nand_scan_ident()
         * can overwrite this value if the DT provides a different value.
         */
        nand->ecc.mode = NAND_ECC_HW;
        nand->ecc.hwctl = fsmc_enable_hwecc;
        nand->ecc.size = 512;
        nand->badblockbits = 7;

        switch (host->mode) {
        case USE_DMA_ACCESS:
                dma_cap_zero(mask);
                dma_cap_set(DMA_MEMCPY, mask);
                host->read_dma_chan = dma_request_channel(mask, filter, NULL);
                if (!host->read_dma_chan) {
                        dev_err(&pdev->dev, "Unable to get read dma channel\n");
                        goto err_req_read_chnl;
                }
                host->write_dma_chan = dma_request_channel(mask, filter, NULL);
                if (!host->write_dma_chan) {
                        dev_err(&pdev->dev, "Unable to get write dma channel\n");
                        goto err_req_write_chnl;
                }
                nand->read_buf = fsmc_read_buf_dma;
                nand->write_buf = fsmc_write_buf_dma;
                break;

        default:
        case USE_WORD_ACCESS:
                nand->read_buf = fsmc_read_buf;
                nand->write_buf = fsmc_write_buf;
                break;
        }

        if (host->dev_timings)
                fsmc_nand_setup(host, host->dev_timings);
        else
                nand->setup_data_interface = fsmc_setup_data_interface;

        if (AMBA_REV_BITS(host->pid) >= 8) {
                nand->ecc.read_page = fsmc_read_page_hwecc;
                nand->ecc.calculate = fsmc_read_hwecc_ecc4;
                nand->ecc.correct = fsmc_bch8_correct_data;
                nand->ecc.bytes = 13;
                nand->ecc.strength = 8;
        }

        /*
         * Scan to find existence of the device
         */
        ret = nand_scan_ident(mtd, 1, NULL);
        if (ret) {
                dev_err(&pdev->dev, "No NAND Device found!\n");
                goto err_scan_ident;
        }

        if (AMBA_REV_BITS(host->pid) >= 8) {
                switch (mtd->oobsize) {
                case 16:
                case 64:
                case 128:
                case 224:
                case 256:
                        break;
                default:
                        dev_warn(&pdev->dev, "No oob scheme defined for oobsize %d\n",
                                 mtd->oobsize);
                        ret = -EINVAL;
                        goto err_probe;
                }

                mtd_set_ooblayout(mtd, &fsmc_ecc4_ooblayout_ops);
        } else {
                switch (nand->ecc.mode) {
                case NAND_ECC_HW:
                        dev_info(&pdev->dev, "Using 1-bit HW ECC scheme\n");
                        nand->ecc.calculate = fsmc_read_hwecc_ecc1;
                        nand->ecc.correct = nand_correct_data;
                        nand->ecc.bytes = 3;
                        nand->ecc.strength = 1;
                        break;

                case NAND_ECC_SOFT:
                        if (nand->ecc.algo == NAND_ECC_BCH) {
                                dev_info(&pdev->dev, "Using 4-bit SW BCH ECC scheme\n");
                                break;
                        }

                case NAND_ECC_ON_DIE:
                        break;

                default:
                        dev_err(&pdev->dev, "Unsupported ECC mode!\n");
                        goto err_probe;
                }

                /*
                 * Don't set layout for BCH4 SW ECC. This will be
                 * generated later in nand_bch_init() later.
                 */
                if (nand->ecc.mode == NAND_ECC_HW) {
                        switch (mtd->oobsize) {
                        case 16:
                        case 64:
                        case 128:
                                mtd_set_ooblayout(mtd,
                                                  &fsmc_ecc1_ooblayout_ops);
                                break;
                        default:
                                dev_warn(&pdev->dev,
                                         "No oob scheme defined for oobsize %d\n",
                                         mtd->oobsize);
                                ret = -EINVAL;
                                goto err_probe;
                        }
                }
        }

        /* Second stage of scan to fill MTD data-structures */
        ret = nand_scan_tail(mtd);
        if (ret)
                goto err_probe;

        mtd->name = "nand";
        ret = mtd_device_register(mtd, NULL, 0);
        if (ret)
                goto err_probe;

        platform_set_drvdata(pdev, host);
        dev_info(&pdev->dev, "FSMC NAND driver registration successful\n");
        return 0;

err_probe:
err_scan_ident:
        if (host->mode == USE_DMA_ACCESS)
                dma_release_channel(host->write_dma_chan);
err_req_write_chnl:
        if (host->mode == USE_DMA_ACCESS)
                dma_release_channel(host->read_dma_chan);
err_req_read_chnl:
        clk_disable_unprepare(host->clk);
        return ret;
}

/*
 * Clean up routine
 */
static int fsmc_nand_remove(struct platform_device *pdev)
{
        struct fsmc_nand_data *host = platform_get_drvdata(pdev);

        if (host) {
                nand_release(nand_to_mtd(&host->nand));

                if (host->mode == USE_DMA_ACCESS) {
                        dma_release_channel(host->write_dma_chan);
                        dma_release_channel(host->read_dma_chan);
                }
                clk_disable_unprepare(host->clk);
        }

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int fsmc_nand_suspend(struct device *dev)
{
        struct fsmc_nand_data *host = dev_get_drvdata(dev);
        if (host)
                clk_disable_unprepare(host->clk);
        return 0;
}

static int fsmc_nand_resume(struct device *dev)
{
        struct fsmc_nand_data *host = dev_get_drvdata(dev);
        if (host) {
                clk_prepare_enable(host->clk);
                if (host->dev_timings)
                        fsmc_nand_setup(host, host->dev_timings);
        }
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(fsmc_nand_pm_ops, fsmc_nand_suspend, fsmc_nand_resume);

static const struct of_device_id fsmc_nand_id_table[] = {
        { .compatible = "st,spear600-fsmc-nand" },
        { .compatible = "stericsson,fsmc-nand" },
        {}
};
MODULE_DEVICE_TABLE(of, fsmc_nand_id_table);

static struct platform_driver fsmc_nand_driver = {
        .remove = fsmc_nand_remove,
        .driver = {
                .name = "fsmc-nand",
                .of_match_table = fsmc_nand_id_table,
                .pm = &fsmc_nand_pm_ops,
        },
};

module_platform_driver_probe(fsmc_nand_driver, fsmc_nand_probe);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Vipin Kumar <vipin.kumar@st.com>, Ashish Priyadarshi");
MODULE_DESCRIPTION("NAND driver for SPEAr Platforms");