// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * davinci_nand.c - NAND Flash Driver for DaVinci family chips
 *
 * Copyright © 2006 Texas Instruments.
 *
 * Port to 2.6.23 Copyright © 2008 by:
 *   Sander Huijsen <Shuijsen@optelecom-nkf.com>
 *   Troy Kisky <troy.kisky@boundarydevices.com>
 *   Dirk Behme <Dirk.Behme@gmail.com>
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/memory/ti-aemif.h>
#include <linux/module.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/rawnand.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>

#define NRCSR_OFFSET            0x00
#define NANDFCR_OFFSET          0x60
#define NANDFSR_OFFSET          0x64
#define NANDF1ECC_OFFSET        0x70

/* 4-bit ECC syndrome registers */
#define NAND_4BIT_ECC_LOAD_OFFSET       0xbc
#define NAND_4BIT_ECC1_OFFSET           0xc0
#define NAND_4BIT_ECC2_OFFSET           0xc4
#define NAND_4BIT_ECC3_OFFSET           0xc8
#define NAND_4BIT_ECC4_OFFSET           0xcc
#define NAND_ERR_ADD1_OFFSET            0xd0
#define NAND_ERR_ADD2_OFFSET            0xd4
#define NAND_ERR_ERRVAL1_OFFSET         0xd8
#define NAND_ERR_ERRVAL2_OFFSET         0xdc

/* NOTE:  boards don't need to use these address bits
 * for ALE/CLE unless they support booting from NAND.
 * They're used unless platform data overrides them.
 */
#define MASK_ALE                0x08
#define MASK_CLE                0x10

#define MAX_TSU_PS              3000    /* Input setup time in ps */
#define MAX_TH_PS               1600    /* Input hold time in ps */

struct davinci_nand_pdata {
        uint32_t                mask_ale;
        uint32_t                mask_cle;

        /*
         * 0-indexed chip-select number of the asynchronous
         * interface to which the NAND device has been connected.
         *
         * So, if you have NAND connected to CS3 of DA850, you
         * will pass '1' here. Since the asynchronous interface
         * on DA850 starts from CS2.
         */
        uint32_t                core_chipsel;

        /* for packages using two chipselects */
        uint32_t                mask_chipsel;

        /* board's default static partition info */
        struct mtd_partition    *parts;
        unsigned int            nr_parts;

        /* none  == NAND_ECC_ENGINE_TYPE_NONE (strongly *not* advised!!)
         * soft  == NAND_ECC_ENGINE_TYPE_SOFT
         * on-die == NAND_ECC_ENGINE_TYPE_ON_DIE
         * else  == NAND_ECC_ENGINE_TYPE_ON_HOST, according to ecc_bits
         *
         * All DaVinci-family chips support 1-bit hardware ECC.
         * Newer ones also support 4-bit ECC, but are awkward
         * using it with large page chips.
         */
        enum nand_ecc_engine_type engine_type;
        enum nand_ecc_placement ecc_placement;
        u8                      ecc_bits;

        /* e.g. NAND_BUSWIDTH_16 */
        unsigned int            options;
        /* e.g. NAND_BBT_USE_FLASH */
        unsigned int            bbt_options;

        /* Main and mirror bbt descriptor overrides */
        struct nand_bbt_descr   *bbt_td;
        struct nand_bbt_descr   *bbt_md;
};

/*
 * This is a device driver for the NAND flash controller found on the
 * various DaVinci family chips.  It handles up to four SoC chipselects,
 * and some flavors of secondary chipselect (e.g. based on A12) as used
 * with multichip packages.
 *
 * The 1-bit ECC hardware is supported, as well as the newer 4-bit ECC
 * available on chips like the DM355 and OMAP-L137 and needed with the
 * more error-prone MLC NAND chips.
 *
 * This driver assumes EM_WAIT connects all the NAND devices' RDY/nBUSY
 * outputs in a "wire-AND" configuration, with no per-chip signals.
 */
struct davinci_nand_info {
        struct nand_controller  controller;
        struct nand_chip        chip;

        struct platform_device  *pdev;

        bool                    is_readmode;

        void __iomem            *base;
        void __iomem            *vaddr;

        void __iomem            *current_cs;

        uint32_t                mask_chipsel;
        uint32_t                mask_ale;
        uint32_t                mask_cle;

        uint32_t                core_chipsel;

        struct clk              *clk;
        struct aemif_device     *aemif;
};

static DEFINE_SPINLOCK(davinci_nand_lock);
static bool ecc4_busy;

static inline struct davinci_nand_info *to_davinci_nand(struct mtd_info *mtd)
{
        return container_of(mtd_to_nand(mtd), struct davinci_nand_info, chip);
}

static inline unsigned int davinci_nand_readl(struct davinci_nand_info *info,
                int offset)
{
        return __raw_readl(info->base + offset);
}

static inline void davinci_nand_writel(struct davinci_nand_info *info,
                int offset, unsigned long value)
{
        __raw_writel(value, info->base + offset);
}

/*----------------------------------------------------------------------*/

/*
 * 1-bit hardware ECC ... context maintained for each core chipselect
 */

static inline uint32_t nand_davinci_readecc_1bit(struct mtd_info *mtd)
{
        struct davinci_nand_info *info = to_davinci_nand(mtd);

        return davinci_nand_readl(info, NANDF1ECC_OFFSET
                        + 4 * info->core_chipsel);
}

static void nand_davinci_hwctl_1bit(struct nand_chip *chip, int mode)
{
        struct davinci_nand_info *info;
        uint32_t nandcfr;
        unsigned long flags;

        info = to_davinci_nand(nand_to_mtd(chip));

        /* Reset ECC hardware */
        nand_davinci_readecc_1bit(nand_to_mtd(chip));

        spin_lock_irqsave(&davinci_nand_lock, flags);

        /* Restart ECC hardware */
        nandcfr = davinci_nand_readl(info, NANDFCR_OFFSET);
        nandcfr |= BIT(8 + info->core_chipsel);
        davinci_nand_writel(info, NANDFCR_OFFSET, nandcfr);

        spin_unlock_irqrestore(&davinci_nand_lock, flags);
}

/*
 * Read hardware ECC value and pack into three bytes
 */
static int nand_davinci_calculate_1bit(struct nand_chip *chip,
                                       const u_char *dat, u_char *ecc_code)
{
        unsigned int ecc_val = nand_davinci_readecc_1bit(nand_to_mtd(chip));
        unsigned int ecc24 = (ecc_val & 0x0fff) | ((ecc_val & 0x0fff0000) >> 4);

        /* invert so that erased block ecc is correct */
        ecc24 = ~ecc24;
        ecc_code[0] = (u_char)(ecc24);
        ecc_code[1] = (u_char)(ecc24 >> 8);
        ecc_code[2] = (u_char)(ecc24 >> 16);

        return 0;
}

static int nand_davinci_correct_1bit(struct nand_chip *chip, u_char *dat,
                                     u_char *read_ecc, u_char *calc_ecc)
{
        uint32_t eccNand = read_ecc[0] | (read_ecc[1] << 8) |
                                          (read_ecc[2] << 16);
        uint32_t eccCalc = calc_ecc[0] | (calc_ecc[1] << 8) |
                                          (calc_ecc[2] << 16);
        uint32_t diff = eccCalc ^ eccNand;

        if (diff) {
                if ((((diff >> 12) ^ diff) & 0xfff) == 0xfff) {
                        /* Correctable error */
                        if ((diff >> (12 + 3)) < chip->ecc.size) {
                                dat[diff >> (12 + 3)] ^= BIT((diff >> 12) & 7);
                                return 1;
                        } else {
                                return -EBADMSG;
                        }
                } else if (!(diff & (diff - 1))) {
                        /* Single bit ECC error in the ECC itself,
                         * nothing to fix */
                        return 1;
                } else {
                        /* Uncorrectable error */
                        return -EBADMSG;
                }

        }
        return 0;
}

/*----------------------------------------------------------------------*/

/*
 * 4-bit hardware ECC ... context maintained over entire AEMIF
 *
 * This is a syndrome engine, but we avoid NAND_ECC_PLACEMENT_INTERLEAVED
 * since that forces use of a problematic "infix OOB" layout.
 * Among other things, it trashes manufacturer bad block markers.
 * Also, and specific to this hardware, it ECC-protects the "prepad"
 * in the OOB ... while having ECC protection for parts of OOB would
 * seem useful, the current MTD stack sometimes wants to update the
 * OOB without recomputing ECC.
 */

static void nand_davinci_hwctl_4bit(struct nand_chip *chip, int mode)
{
        struct davinci_nand_info *info = to_davinci_nand(nand_to_mtd(chip));
        unsigned long flags;
        u32 val;

        /* Reset ECC hardware */
        davinci_nand_readl(info, NAND_4BIT_ECC1_OFFSET);

        spin_lock_irqsave(&davinci_nand_lock, flags);

        /* Start 4-bit ECC calculation for read/write */
        val = davinci_nand_readl(info, NANDFCR_OFFSET);
        val &= ~(0x03 << 4);
        val |= (info->core_chipsel << 4) | BIT(12);
        davinci_nand_writel(info, NANDFCR_OFFSET, val);

        info->is_readmode = (mode == NAND_ECC_READ);

        spin_unlock_irqrestore(&davinci_nand_lock, flags);
}

/* Read raw ECC code after writing to NAND. */
static void
nand_davinci_readecc_4bit(struct davinci_nand_info *info, u32 code[4])
{
        const u32 mask = 0x03ff03ff;

        code[0] = davinci_nand_readl(info, NAND_4BIT_ECC1_OFFSET) & mask;
        code[1] = davinci_nand_readl(info, NAND_4BIT_ECC2_OFFSET) & mask;
        code[2] = davinci_nand_readl(info, NAND_4BIT_ECC3_OFFSET) & mask;
        code[3] = davinci_nand_readl(info, NAND_4BIT_ECC4_OFFSET) & mask;
}

/* Terminate read ECC; or return ECC (as bytes) of data written to NAND. */
static int nand_davinci_calculate_4bit(struct nand_chip *chip,
                                       const u_char *dat, u_char *ecc_code)
{
        struct davinci_nand_info *info = to_davinci_nand(nand_to_mtd(chip));
        u32 raw_ecc[4], *p;
        unsigned i;

        /* After a read, terminate ECC calculation by a dummy read
         * of some 4-bit ECC register.  ECC covers everything that
         * was read; correct() just uses the hardware state, so
         * ecc_code is not needed.
         */
        if (info->is_readmode) {
                davinci_nand_readl(info, NAND_4BIT_ECC1_OFFSET);
                return 0;
        }

        /* Pack eight raw 10-bit ecc values into ten bytes, making
         * two passes which each convert four values (in upper and
         * lower halves of two 32-bit words) into five bytes.  The
         * ROM boot loader uses this same packing scheme.
         */
        nand_davinci_readecc_4bit(info, raw_ecc);
        for (i = 0, p = raw_ecc; i < 2; i++, p += 2) {
                *ecc_code++ =   p[0]        & 0xff;
                *ecc_code++ = ((p[0] >>  8) & 0x03) | ((p[0] >> 14) & 0xfc);
                *ecc_code++ = ((p[0] >> 22) & 0x0f) | ((p[1] <<  4) & 0xf0);
                *ecc_code++ = ((p[1] >>  4) & 0x3f) | ((p[1] >> 10) & 0xc0);
                *ecc_code++ =  (p[1] >> 18) & 0xff;
        }

        return 0;
}

/* Correct up to 4 bits in data we just read, using state left in the
 * hardware plus the ecc_code computed when it was first written.
 */
static int nand_davinci_correct_4bit(struct nand_chip *chip, u_char *data,
                                     u_char *ecc_code, u_char *null)
{
        int i;
        struct davinci_nand_info *info = to_davinci_nand(nand_to_mtd(chip));
        unsigned short ecc10[8];
        unsigned short *ecc16;
        u32 syndrome[4];
        u32 ecc_state;
        unsigned num_errors, corrected;
        unsigned long timeo;

        /* Unpack ten bytes into eight 10 bit values.  We know we're
         * little-endian, and use type punning for less shifting/masking.
         */
        if (WARN_ON(0x01 & (uintptr_t)ecc_code))
                return -EINVAL;
        ecc16 = (unsigned short *)ecc_code;

        ecc10[0] =  (ecc16[0] >>  0) & 0x3ff;
        ecc10[1] = ((ecc16[0] >> 10) & 0x3f) | ((ecc16[1] << 6) & 0x3c0);
        ecc10[2] =  (ecc16[1] >>  4) & 0x3ff;
        ecc10[3] = ((ecc16[1] >> 14) & 0x3)  | ((ecc16[2] << 2) & 0x3fc);
        ecc10[4] =  (ecc16[2] >>  8)         | ((ecc16[3] << 8) & 0x300);
        ecc10[5] =  (ecc16[3] >>  2) & 0x3ff;
        ecc10[6] = ((ecc16[3] >> 12) & 0xf)  | ((ecc16[4] << 4) & 0x3f0);
        ecc10[7] =  (ecc16[4] >>  6) & 0x3ff;

        /* Tell ECC controller about the expected ECC codes. */
        for (i = 7; i >= 0; i--)
                davinci_nand_writel(info, NAND_4BIT_ECC_LOAD_OFFSET, ecc10[i]);

        /* Allow time for syndrome calculation ... then read it.
         * A syndrome of all zeroes 0 means no detected errors.
         */
        davinci_nand_readl(info, NANDFSR_OFFSET);
        nand_davinci_readecc_4bit(info, syndrome);
        if (!(syndrome[0] | syndrome[1] | syndrome[2] | syndrome[3]))
                return 0;

        /*
         * Clear any previous address calculation by doing a dummy read of an
         * error address register.
         */
        davinci_nand_readl(info, NAND_ERR_ADD1_OFFSET);

        /* Start address calculation, and wait for it to complete.
         * We _could_ start reading more data while this is working,
         * to speed up the overall page read.
         */
        davinci_nand_writel(info, NANDFCR_OFFSET,
                        davinci_nand_readl(info, NANDFCR_OFFSET) | BIT(13));

        /*
         * ECC_STATE field reads 0x3 (Error correction complete) immediately
         * after setting the 4BITECC_ADD_CALC_START bit. So if you immediately
         * begin trying to poll for the state, you may fall right out of your
         * loop without any of the correction calculations having taken place.
         * The recommendation from the hardware team is to initially delay as
         * long as ECC_STATE reads less than 4. After that, ECC HW has entered
         * correction state.
         */
        timeo = jiffies + usecs_to_jiffies(100);
        do {
                ecc_state = (davinci_nand_readl(info,
                                NANDFSR_OFFSET) >> 8) & 0x0f;
                cpu_relax();
        } while ((ecc_state < 4) && time_before(jiffies, timeo));

        for (;;) {
                u32     fsr = davinci_nand_readl(info, NANDFSR_OFFSET);

                switch ((fsr >> 8) & 0x0f) {
                case 0:         /* no error, should not happen */
                        davinci_nand_readl(info, NAND_ERR_ERRVAL1_OFFSET);
                        return 0;
                case 1:         /* five or more errors detected */
                        davinci_nand_readl(info, NAND_ERR_ERRVAL1_OFFSET);
                        return -EBADMSG;
                case 2:         /* error addresses computed */
                case 3:
                        num_errors = 1 + ((fsr >> 16) & 0x03);
                        goto correct;
                default:        /* still working on it */
                        cpu_relax();
                        continue;
                }
        }

correct:
        /* correct each error */
        for (i = 0, corrected = 0; i < num_errors; i++) {
                int error_address, error_value;

                if (i > 1) {
                        error_address = davinci_nand_readl(info,
                                                NAND_ERR_ADD2_OFFSET);
                        error_value = davinci_nand_readl(info,
                                                NAND_ERR_ERRVAL2_OFFSET);
                } else {
                        error_address = davinci_nand_readl(info,
                                                NAND_ERR_ADD1_OFFSET);
                        error_value = davinci_nand_readl(info,
                                                NAND_ERR_ERRVAL1_OFFSET);
                }

                if (i & 1) {
                        error_address >>= 16;
                        error_value >>= 16;
                }
                error_address &= 0x3ff;
                error_address = (512 + 7) - error_address;

                if (error_address < 512) {
                        data[error_address] ^= error_value;
                        corrected++;
                }
        }

        return corrected;
}

/*----------------------------------------------------------------------*/

/* An ECC layout for using 4-bit ECC with small-page flash, storing
 * ten ECC bytes plus the manufacturer's bad block marker byte, and
 * and not overlapping the default BBT markers.
 */
static int hwecc4_ooblayout_small_ecc(struct mtd_info *mtd, int section,
                                      struct mtd_oob_region *oobregion)
{
        if (section > 2)
                return -ERANGE;

        if (!section) {
                oobregion->offset = 0;
                oobregion->length = 5;
        } else if (section == 1) {
                oobregion->offset = 6;
                oobregion->length = 2;
        } else {
                oobregion->offset = 13;
                oobregion->length = 3;
        }

        return 0;
}

static int hwecc4_ooblayout_small_free(struct mtd_info *mtd, int section,
                                       struct mtd_oob_region *oobregion)
{
        if (section > 1)
                return -ERANGE;

        if (!section) {
                oobregion->offset = 8;
                oobregion->length = 5;
        } else {
                oobregion->offset = 16;
                oobregion->length = mtd->oobsize - 16;
        }

        return 0;
}

static const struct mtd_ooblayout_ops hwecc4_small_ooblayout_ops = {
        .ecc = hwecc4_ooblayout_small_ecc,
        .free = hwecc4_ooblayout_small_free,
};

static int hwecc4_ooblayout_large_ecc(struct mtd_info *mtd, int section,
                                       struct mtd_oob_region *oobregion)
{
        struct nand_device *nand = mtd_to_nanddev(mtd);
        unsigned int total_ecc_bytes = nand->ecc.ctx.total;
        int nregions = total_ecc_bytes / 10; /* 10 bytes per chunk */

        if (section >= nregions)
                return -ERANGE;

        oobregion->offset = (section * 16) + 6;
        oobregion->length = 10;

        return 0;
}

static int hwecc4_ooblayout_large_free(struct mtd_info *mtd, int section,
                                       struct mtd_oob_region *oobregion)
{
        struct nand_device *nand = mtd_to_nanddev(mtd);
        unsigned int total_ecc_bytes = nand->ecc.ctx.total;
        int nregions = total_ecc_bytes / 10; /* 10 bytes per chunk */

        /* First region is used for BBT */
        if (section >= (nregions - 1))
                return -ERANGE;

        oobregion->offset = ((section + 1) * 16);
        oobregion->length = 6;

        return 0;
}

static const struct mtd_ooblayout_ops hwecc4_large_ooblayout_ops = {
        .ecc = hwecc4_ooblayout_large_ecc,
        .free = hwecc4_ooblayout_large_free,
};

#if defined(CONFIG_OF)
static const struct of_device_id davinci_nand_of_match[] = {
        {.compatible = "ti,davinci-nand", },
        {.compatible = "ti,keystone-nand", },
        {},
};
MODULE_DEVICE_TABLE(of, davinci_nand_of_match);

static struct davinci_nand_pdata *
nand_davinci_get_pdata(struct platform_device *pdev)
{
        if (!dev_get_platdata(&pdev->dev)) {
                struct davinci_nand_pdata *pdata;
                const char *mode;
                u32 prop;

                pdata =  devm_kzalloc(&pdev->dev,
                                sizeof(struct davinci_nand_pdata),
                                GFP_KERNEL);
                pdev->dev.platform_data = pdata;
                if (!pdata)
                        return ERR_PTR(-ENOMEM);
                if (!device_property_read_u32(&pdev->dev,
                                              "ti,davinci-chipselect", &prop))
                        pdata->core_chipsel = prop;
                else
                        return ERR_PTR(-EINVAL);

                if (!device_property_read_u32(&pdev->dev,
                                              "ti,davinci-mask-ale", &prop))
                        pdata->mask_ale = prop;
                if (!device_property_read_u32(&pdev->dev,
                                              "ti,davinci-mask-cle", &prop))
                        pdata->mask_cle = prop;
                if (!device_property_read_u32(&pdev->dev,
                                              "ti,davinci-mask-chipsel", &prop))
                        pdata->mask_chipsel = prop;
                if (!device_property_read_string(&pdev->dev,
                                                 "ti,davinci-ecc-mode",
                                                 &mode)) {
                        if (!strncmp("none", mode, 4))
                                pdata->engine_type = NAND_ECC_ENGINE_TYPE_NONE;
                        if (!strncmp("soft", mode, 4))
                                pdata->engine_type = NAND_ECC_ENGINE_TYPE_SOFT;
                        if (!strncmp("hw", mode, 2))
                                pdata->engine_type = NAND_ECC_ENGINE_TYPE_ON_HOST;
                        if (!strncmp("on-die", mode, 6))
                                pdata->engine_type = NAND_ECC_ENGINE_TYPE_ON_DIE;
                }
                if (!device_property_read_u32(&pdev->dev,
                                              "ti,davinci-ecc-bits", &prop))
                        pdata->ecc_bits = prop;

                if (!device_property_read_u32(&pdev->dev,
                                              "ti,davinci-nand-buswidth",
                                              &prop) && prop == 16)
                        pdata->options |= NAND_BUSWIDTH_16;

                if (device_property_read_bool(&pdev->dev,
                                              "ti,davinci-nand-use-bbt"))
                        pdata->bbt_options = NAND_BBT_USE_FLASH;

                /*
                 * Since kernel v4.8, this driver has been fixed to enable
                 * use of 4-bit hardware ECC with subpages and verified on
                 * TI's keystone EVMs (K2L, K2HK and K2E).
                 * However, in the interest of not breaking systems using
                 * existing UBI partitions, sub-page writes are not being
                 * (re)enabled. If you want to use subpage writes on Keystone
                 * platforms (i.e. do not have any existing UBI partitions),
                 * then use "ti,davinci-nand" as the compatible in your
                 * device-tree file.
                 */
                if (device_is_compatible(&pdev->dev, "ti,keystone-nand"))
                        pdata->options |= NAND_NO_SUBPAGE_WRITE;
        }

        return dev_get_platdata(&pdev->dev);
}
#else
static struct davinci_nand_pdata *
nand_davinci_get_pdata(struct platform_device *pdev)
{
        return dev_get_platdata(&pdev->dev);
}
#endif

static int davinci_nand_attach_chip(struct nand_chip *chip)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        struct davinci_nand_info *info = to_davinci_nand(mtd);
        struct davinci_nand_pdata *pdata = nand_davinci_get_pdata(info->pdev);
        int ret = 0;

        if (IS_ERR(pdata))
                return PTR_ERR(pdata);

        /* Use board-specific ECC config */
        chip->ecc.engine_type = pdata->engine_type;
        chip->ecc.placement = pdata->ecc_placement;

        switch (chip->ecc.engine_type) {
        case NAND_ECC_ENGINE_TYPE_NONE:
        case NAND_ECC_ENGINE_TYPE_ON_DIE:
                pdata->ecc_bits = 0;
                break;
        case NAND_ECC_ENGINE_TYPE_SOFT:
                pdata->ecc_bits = 0;
                /*
                 * This driver expects Hamming based ECC when engine_type is set
                 * to NAND_ECC_ENGINE_TYPE_SOFT. Force ecc.algo to
                 * NAND_ECC_ALGO_HAMMING to avoid adding an extra ->ecc_algo
                 * field to davinci_nand_pdata.
                 */
                chip->ecc.algo = NAND_ECC_ALGO_HAMMING;
                break;
        case NAND_ECC_ENGINE_TYPE_ON_HOST:
                if (pdata->ecc_bits == 4) {
                        int chunks = mtd->writesize / 512;

                        if (!chunks || mtd->oobsize < 16) {
                                dev_dbg(&info->pdev->dev, "too small\n");
                                return -EINVAL;
                        }

                        /*
                         * No sanity checks:  CPUs must support this,
                         * and the chips may not use NAND_BUSWIDTH_16.
                         */

                        /* No sharing 4-bit hardware between chipselects yet */
                        spin_lock_irq(&davinci_nand_lock);
                        if (ecc4_busy)
                                ret = -EBUSY;
                        else
                                ecc4_busy = true;
                        spin_unlock_irq(&davinci_nand_lock);

                        if (ret == -EBUSY)
                                return ret;

                        chip->ecc.calculate = nand_davinci_calculate_4bit;
                        chip->ecc.correct = nand_davinci_correct_4bit;
                        chip->ecc.hwctl = nand_davinci_hwctl_4bit;
                        chip->ecc.bytes = 10;
                        chip->ecc.options = NAND_ECC_GENERIC_ERASED_CHECK;
                        chip->ecc.algo = NAND_ECC_ALGO_BCH;

                        /*
                         * Update ECC layout if needed ... for 1-bit HW ECC, the
                         * default is OK, but it allocates 6 bytes when only 3
                         * are needed (for each 512 bytes). For 4-bit HW ECC,
                         * the default is not usable: 10 bytes needed, not 6.
                         *
                         * For small page chips, preserve the manufacturer's
                         * badblock marking data ... and make sure a flash BBT
                         * table marker fits in the free bytes.
                         */
                        if (chunks == 1) {
                                mtd_set_ooblayout(mtd,
                                                  &hwecc4_small_ooblayout_ops);
                        } else if (chunks == 4 || chunks == 8) {
                                chip->ecc.read_page = nand_read_page_hwecc_oob_first;

                                if (chip->options & NAND_IS_BOOT_MEDIUM)
                                        mtd_set_ooblayout(mtd, &hwecc4_large_ooblayout_ops);
                                else
                                        mtd_set_ooblayout(mtd, nand_get_large_page_ooblayout());
                        } else {
                                return -EIO;
                        }
                } else {
                        /* 1bit ecc hamming */
                        chip->ecc.calculate = nand_davinci_calculate_1bit;
                        chip->ecc.correct = nand_davinci_correct_1bit;
                        chip->ecc.hwctl = nand_davinci_hwctl_1bit;
                        chip->ecc.bytes = 3;
                        chip->ecc.algo = NAND_ECC_ALGO_HAMMING;
                }
                chip->ecc.size = 512;
                chip->ecc.strength = pdata->ecc_bits;
                break;
        default:
                return -EINVAL;
        }

        return ret;
}

static void nand_davinci_data_in(struct davinci_nand_info *info, void *buf,
                                 unsigned int len, bool force_8bit)
{
        u32 alignment = ((uintptr_t)buf | len) & 3;

        if (force_8bit || (alignment & 1))
                ioread8_rep(info->current_cs, buf, len);
        else if (alignment & 3)
                ioread16_rep(info->current_cs, buf, len >> 1);
        else
                ioread32_rep(info->current_cs, buf, len >> 2);
}

static void nand_davinci_data_out(struct davinci_nand_info *info,
                                  const void *buf, unsigned int len,
                                  bool force_8bit)
{
        u32 alignment = ((uintptr_t)buf | len) & 3;

        if (force_8bit || (alignment & 1))
                iowrite8_rep(info->current_cs, buf, len);
        else if (alignment & 3)
                iowrite16_rep(info->current_cs, buf, len >> 1);
        else
                iowrite32_rep(info->current_cs, buf, len >> 2);
}

static int davinci_nand_exec_instr(struct davinci_nand_info *info,
                                   const struct nand_op_instr *instr)
{
        unsigned int i, timeout_us;
        u32 status;
        int ret;

        switch (instr->type) {
        case NAND_OP_CMD_INSTR:
                iowrite8(instr->ctx.cmd.opcode,
                         info->current_cs + info->mask_cle);
                break;

        case NAND_OP_ADDR_INSTR:
                for (i = 0; i < instr->ctx.addr.naddrs; i++) {
                        iowrite8(instr->ctx.addr.addrs[i],
                                 info->current_cs + info->mask_ale);
                }
                break;

        case NAND_OP_DATA_IN_INSTR:
                nand_davinci_data_in(info, instr->ctx.data.buf.in,
                                     instr->ctx.data.len,
                                     instr->ctx.data.force_8bit);
                break;

        case NAND_OP_DATA_OUT_INSTR:
                nand_davinci_data_out(info, instr->ctx.data.buf.out,
                                      instr->ctx.data.len,
                                      instr->ctx.data.force_8bit);
                break;

        case NAND_OP_WAITRDY_INSTR:
                timeout_us = instr->ctx.waitrdy.timeout_ms * 1000;
                ret = readl_relaxed_poll_timeout(info->base + NANDFSR_OFFSET,
                                                 status, status & BIT(0), 5,
                                                 timeout_us);
                if (ret)
                        return ret;

                break;
        }

        if (instr->delay_ns) {
                /* Dummy read to be sure that command is sent before ndelay starts */
                davinci_nand_readl(info, 0);
                ndelay(instr->delay_ns);
        }

        return 0;
}

static int davinci_nand_exec_op(struct nand_chip *chip,
                                const struct nand_operation *op,
                                bool check_only)
{
        struct davinci_nand_info *info = to_davinci_nand(nand_to_mtd(chip));
        unsigned int i;

        if (check_only)
                return 0;

        info->current_cs = info->vaddr + (op->cs * info->mask_chipsel);

        for (i = 0; i < op->ninstrs; i++) {
                int ret;

                ret = davinci_nand_exec_instr(info, &op->instrs[i]);
                if (ret)
                        return ret;
        }

        return 0;
}

#define TO_CYCLES(ps, period_ns) (DIV_ROUND_UP((ps) / 1000, (period_ns)))

static int davinci_nand_setup_interface(struct nand_chip *chip, int chipnr,
                                        const struct nand_interface_config *conf)
{
        struct davinci_nand_info *info = to_davinci_nand(nand_to_mtd(chip));
        const struct nand_sdr_timings *sdr;
        struct aemif_cs_timings timings;
        s32 cfg, min, cyc_ns;
        int ret;

        cyc_ns = 1000000000 / clk_get_rate(info->clk);

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

        cfg = TO_CYCLES(sdr->tCLR_min, cyc_ns) - 1;
        timings.rsetup = cfg > 0 ? cfg : 0;

        cfg = max_t(s32, TO_CYCLES(sdr->tREA_max + MAX_TSU_PS, cyc_ns),
                    TO_CYCLES(sdr->tRP_min, cyc_ns)) - 1;
        timings.rstrobe = cfg > 0 ? cfg : 0;

        min = TO_CYCLES(sdr->tCEA_max + MAX_TSU_PS, cyc_ns) - 2;
        while ((s32)(timings.rsetup + timings.rstrobe) < min)
                timings.rstrobe++;

        cfg = TO_CYCLES((s32)(MAX_TH_PS - sdr->tCHZ_max), cyc_ns) - 1;
        timings.rhold = cfg > 0 ? cfg : 0;

        min = TO_CYCLES(sdr->tRC_min, cyc_ns) - 3;
        while ((s32)(timings.rsetup + timings.rstrobe + timings.rhold) < min)
                timings.rhold++;

        cfg = TO_CYCLES((s32)(sdr->tRHZ_max - (timings.rhold + 1) * cyc_ns * 1000), cyc_ns);
        cfg = max_t(s32, cfg, TO_CYCLES(sdr->tCHZ_max, cyc_ns)) - 1;
        timings.ta = cfg > 0 ? cfg : 0;

        cfg = TO_CYCLES(sdr->tWP_min, cyc_ns) - 1;
        timings.wstrobe = cfg > 0 ? cfg : 0;

        cfg = max_t(s32, TO_CYCLES(sdr->tCLS_min, cyc_ns), TO_CYCLES(sdr->tALS_min, cyc_ns));
        cfg = max_t(s32, cfg, TO_CYCLES(sdr->tCS_min, cyc_ns)) - 1;
        timings.wsetup = cfg > 0 ? cfg : 0;

        min = TO_CYCLES(sdr->tDS_min, cyc_ns) - 2;
        while ((s32)(timings.wsetup + timings.wstrobe) < min)
                timings.wstrobe++;

        cfg = max_t(s32, TO_CYCLES(sdr->tCLH_min, cyc_ns), TO_CYCLES(sdr->tALH_min, cyc_ns));
        cfg = max_t(s32, cfg, TO_CYCLES(sdr->tCH_min, cyc_ns));
        cfg = max_t(s32, cfg, TO_CYCLES(sdr->tDH_min, cyc_ns)) - 1;
        timings.whold = cfg > 0 ? cfg : 0;

        min = TO_CYCLES(sdr->tWC_min, cyc_ns) - 2;
        while ((s32)(timings.wsetup + timings.wstrobe + timings.whold) < min)
                timings.whold++;

        dev_dbg(&info->pdev->dev, "RSETUP %x RSTROBE %x RHOLD %x\n",
                timings.rsetup, timings.rstrobe, timings.rhold);
        dev_dbg(&info->pdev->dev, "TA %x\n", timings.ta);
        dev_dbg(&info->pdev->dev, "WSETUP %x WSTROBE %x WHOLD %x\n",
                timings.wsetup, timings.wstrobe, timings.whold);

        ret = aemif_check_cs_timings(&timings);
        if (ret || chipnr == NAND_DATA_IFACE_CHECK_ONLY)
                return ret;

        return aemif_set_cs_timings(info->aemif, info->core_chipsel, &timings);
}

static const struct nand_controller_ops davinci_nand_controller_ops = {
        .attach_chip = davinci_nand_attach_chip,
        .exec_op = davinci_nand_exec_op,
        .setup_interface = davinci_nand_setup_interface,
};

static int nand_davinci_probe(struct platform_device *pdev)
{
        struct davinci_nand_pdata       *pdata;
        struct davinci_nand_info        *info;
        struct resource                 *res1;
        struct resource                 *res2;
        void __iomem                    *vaddr;
        void __iomem                    *base;
        int                             ret;
        uint32_t                        val;
        struct mtd_info                 *mtd;

        pdata = nand_davinci_get_pdata(pdev);
        if (IS_ERR(pdata))
                return PTR_ERR(pdata);

        /* insist on board-specific configuration */
        if (!pdata)
                return -ENODEV;

        /* which external chipselect will we be managing? */
        if (pdata->core_chipsel > 3)
                return -ENODEV;

        info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        platform_set_drvdata(pdev, info);

        res1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        res2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!res1 || !res2) {
                dev_err(&pdev->dev, "resource missing\n");
                return -EINVAL;
        }

        vaddr = devm_ioremap_resource(&pdev->dev, res1);
        if (IS_ERR(vaddr))
                return PTR_ERR(vaddr);

        /*
         * This registers range is used to setup NAND settings. In case with
         * TI AEMIF driver, the same memory address range is requested already
         * by AEMIF, so we cannot request it twice, just ioremap.
         * The AEMIF and NAND drivers not use the same registers in this range.
         */
        base = devm_ioremap(&pdev->dev, res2->start, resource_size(res2));
        if (!base) {
                dev_err(&pdev->dev, "ioremap failed for resource %pR\n", res2);
                return -EADDRNOTAVAIL;
        }

        info->clk = devm_clk_get_enabled(&pdev->dev, "aemif");
        if (IS_ERR(info->clk))
                return dev_err_probe(&pdev->dev, PTR_ERR(info->clk), "failed to get clock");

        info->pdev              = pdev;
        info->base              = base;
        info->vaddr             = vaddr;
        info->aemif             = dev_get_drvdata(pdev->dev.parent);

        mtd                     = nand_to_mtd(&info->chip);
        mtd->dev.parent         = &pdev->dev;
        nand_set_flash_node(&info->chip, pdev->dev.of_node);

        /* options such as NAND_BBT_USE_FLASH */
        info->chip.bbt_options  = pdata->bbt_options;
        /* options such as 16-bit widths */
        info->chip.options      = pdata->options;
        info->chip.bbt_td       = pdata->bbt_td;
        info->chip.bbt_md       = pdata->bbt_md;

        info->current_cs        = info->vaddr;
        info->core_chipsel      = pdata->core_chipsel;
        info->mask_chipsel      = pdata->mask_chipsel;

        /* use nandboot-capable ALE/CLE masks by default */
        info->mask_ale          = pdata->mask_ale ? : MASK_ALE;
        info->mask_cle          = pdata->mask_cle ? : MASK_CLE;

        spin_lock_irq(&davinci_nand_lock);

        /* put CSxNAND into NAND mode */
        val = davinci_nand_readl(info, NANDFCR_OFFSET);
        val |= BIT(info->core_chipsel);
        davinci_nand_writel(info, NANDFCR_OFFSET, val);

        spin_unlock_irq(&davinci_nand_lock);

        /* Scan to find existence of the device(s) */
        nand_controller_init(&info->controller);
        info->controller.ops = &davinci_nand_controller_ops;
        info->chip.controller = &info->controller;
        ret = nand_scan(&info->chip, pdata->mask_chipsel ? 2 : 1);
        if (ret < 0) {
                dev_dbg(&pdev->dev, "no NAND chip(s) found\n");
                return ret;
        }

        if (pdata->parts)
                ret = mtd_device_register(mtd, pdata->parts, pdata->nr_parts);
        else
                ret = mtd_device_register(mtd, NULL, 0);
        if (ret < 0)
                goto err_cleanup_nand;

        val = davinci_nand_readl(info, NRCSR_OFFSET);
        dev_info(&pdev->dev, "controller rev. %d.%d\n",
               (val >> 8) & 0xff, val & 0xff);

        return 0;

err_cleanup_nand:
        nand_cleanup(&info->chip);

        return ret;
}

static void nand_davinci_remove(struct platform_device *pdev)
{
        struct davinci_nand_info *info = platform_get_drvdata(pdev);
        struct nand_chip *chip = &info->chip;
        int ret;

        spin_lock_irq(&davinci_nand_lock);
        if (chip->ecc.placement == NAND_ECC_PLACEMENT_INTERLEAVED)
                ecc4_busy = false;
        spin_unlock_irq(&davinci_nand_lock);

        ret = mtd_device_unregister(nand_to_mtd(chip));
        WARN_ON(ret);
        nand_cleanup(chip);
}

static struct platform_driver nand_davinci_driver = {
        .probe          = nand_davinci_probe,
        .remove         = nand_davinci_remove,
        .driver         = {
                .name   = "davinci_nand",
                .of_match_table = of_match_ptr(davinci_nand_of_match),
        },
};
MODULE_ALIAS("platform:davinci_nand");

module_platform_driver(nand_davinci_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Texas Instruments");
MODULE_DESCRIPTION("Davinci NAND flash driver");