// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2009-2015 Freescale Semiconductor, Inc. and others
 *
 * Description: MPC5125, VF610, MCF54418 and Kinetis K70 Nand driver.
 * Jason ported to M54418TWR and MVFA5 (VF610).
 * Authors: Stefan Agner <stefan.agner@toradex.com>
 *          Bill Pringlemeir <bpringlemeir@nbsps.com>
 *          Shaohui Xie <b21989@freescale.com>
 *          Jason Jin <Jason.jin@freescale.com>
 *
 * Based on original driver mpc5121_nfc.c.
 *
 * Limitations:
 * - Untested on MPC5125 and M54418.
 * - DMA and pipelining not used.
 * - 2K pages or less.
 * - HW ECC: Only 2K page with 64+ OOB.
 * - HW ECC: Only 24 and 32-bit error correction implemented.
 */

#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/init.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_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/swab.h>

#define DRV_NAME                "vf610_nfc"

/* Register Offsets */
#define NFC_FLASH_CMD1                  0x3F00
#define NFC_FLASH_CMD2                  0x3F04
#define NFC_COL_ADDR                    0x3F08
#define NFC_ROW_ADDR                    0x3F0c
#define NFC_ROW_ADDR_INC                0x3F14
#define NFC_FLASH_STATUS1               0x3F18
#define NFC_FLASH_STATUS2               0x3F1c
#define NFC_CACHE_SWAP                  0x3F28
#define NFC_SECTOR_SIZE                 0x3F2c
#define NFC_FLASH_CONFIG                0x3F30
#define NFC_IRQ_STATUS                  0x3F38

/* Addresses for NFC MAIN RAM BUFFER areas */
#define NFC_MAIN_AREA(n)                ((n) *  0x1000)

#define PAGE_2K                         0x0800
#define OOB_64                          0x0040
#define OOB_MAX                         0x0100

/* NFC_CMD2[CODE] controller cycle bit masks */
#define COMMAND_CMD_BYTE1               BIT(14)
#define COMMAND_CAR_BYTE1               BIT(13)
#define COMMAND_CAR_BYTE2               BIT(12)
#define COMMAND_RAR_BYTE1               BIT(11)
#define COMMAND_RAR_BYTE2               BIT(10)
#define COMMAND_RAR_BYTE3               BIT(9)
#define COMMAND_NADDR_BYTES(x)          GENMASK(13, 13 - (x) + 1)
#define COMMAND_WRITE_DATA              BIT(8)
#define COMMAND_CMD_BYTE2               BIT(7)
#define COMMAND_RB_HANDSHAKE            BIT(6)
#define COMMAND_READ_DATA               BIT(5)
#define COMMAND_CMD_BYTE3               BIT(4)
#define COMMAND_READ_STATUS             BIT(3)
#define COMMAND_READ_ID                 BIT(2)

/* NFC ECC mode define */
#define ECC_BYPASS                      0
#define ECC_45_BYTE                     6
#define ECC_60_BYTE                     7

/*** Register Mask and bit definitions */

/* NFC_FLASH_CMD1 Field */
#define CMD_BYTE2_MASK                          0xFF000000
#define CMD_BYTE2_SHIFT                         24

/* NFC_FLASH_CM2 Field */
#define CMD_BYTE1_MASK                          0xFF000000
#define CMD_BYTE1_SHIFT                         24
#define CMD_CODE_MASK                           0x00FFFF00
#define CMD_CODE_SHIFT                          8
#define BUFNO_MASK                              0x00000006
#define BUFNO_SHIFT                             1
#define START_BIT                               BIT(0)

/* NFC_COL_ADDR Field */
#define COL_ADDR_MASK                           0x0000FFFF
#define COL_ADDR_SHIFT                          0
#define COL_ADDR(pos, val)                      (((val) & 0xFF) << (8 * (pos)))

/* NFC_ROW_ADDR Field */
#define ROW_ADDR_MASK                           0x00FFFFFF
#define ROW_ADDR_SHIFT                          0
#define ROW_ADDR(pos, val)                      (((val) & 0xFF) << (8 * (pos)))

#define ROW_ADDR_CHIP_SEL_RB_MASK               0xF0000000
#define ROW_ADDR_CHIP_SEL_RB_SHIFT              28
#define ROW_ADDR_CHIP_SEL_MASK                  0x0F000000
#define ROW_ADDR_CHIP_SEL_SHIFT                 24

/* NFC_FLASH_STATUS2 Field */
#define STATUS_BYTE1_MASK                       0x000000FF

/* NFC_FLASH_CONFIG Field */
#define CONFIG_ECC_SRAM_ADDR_MASK               0x7FC00000
#define CONFIG_ECC_SRAM_ADDR_SHIFT              22
#define CONFIG_ECC_SRAM_REQ_BIT                 BIT(21)
#define CONFIG_DMA_REQ_BIT                      BIT(20)
#define CONFIG_ECC_MODE_MASK                    0x000E0000
#define CONFIG_ECC_MODE_SHIFT                   17
#define CONFIG_FAST_FLASH_BIT                   BIT(16)
#define CONFIG_16BIT                            BIT(7)
#define CONFIG_BOOT_MODE_BIT                    BIT(6)
#define CONFIG_ADDR_AUTO_INCR_BIT               BIT(5)
#define CONFIG_BUFNO_AUTO_INCR_BIT              BIT(4)
#define CONFIG_PAGE_CNT_MASK                    0xF
#define CONFIG_PAGE_CNT_SHIFT                   0

/* NFC_IRQ_STATUS Field */
#define IDLE_IRQ_BIT                            BIT(29)
#define IDLE_EN_BIT                             BIT(20)
#define CMD_DONE_CLEAR_BIT                      BIT(18)
#define IDLE_CLEAR_BIT                          BIT(17)

/*
 * ECC status - seems to consume 8 bytes (double word). The documented
 * status byte is located in the lowest byte of the second word (which is
 * the 4th or 7th byte depending on endianness).
 * Calculate an offset to store the ECC status at the end of the buffer.
 */
#define ECC_SRAM_ADDR           (PAGE_2K + OOB_MAX - 8)

#define ECC_STATUS              0x4
#define ECC_STATUS_MASK         0x80
#define ECC_STATUS_ERR_COUNT    0x3F

enum vf610_nfc_variant {
        NFC_VFC610 = 1,
};

struct vf610_nfc {
        struct nand_controller base;
        struct nand_chip chip;
        struct device *dev;
        void __iomem *regs;
        struct completion cmd_done;
        /* Status and ID are in alternate locations. */
        enum vf610_nfc_variant variant;
        struct clk *clk;
        /*
         * Indicate that user data is accessed (full page/oob). This is
         * useful to indicate the driver whether to swap byte endianness.
         * See comments in vf610_nfc_rd_from_sram/vf610_nfc_wr_to_sram.
         */
        bool data_access;
        u32 ecc_mode;
};

static inline struct vf610_nfc *chip_to_nfc(struct nand_chip *chip)
{
        return container_of(chip, struct vf610_nfc, chip);
}

static inline u32 vf610_nfc_read(struct vf610_nfc *nfc, uint reg)
{
        return readl(nfc->regs + reg);
}

static inline void vf610_nfc_write(struct vf610_nfc *nfc, uint reg, u32 val)
{
        writel(val, nfc->regs + reg);
}

static inline void vf610_nfc_set(struct vf610_nfc *nfc, uint reg, u32 bits)
{
        vf610_nfc_write(nfc, reg, vf610_nfc_read(nfc, reg) | bits);
}

static inline void vf610_nfc_clear(struct vf610_nfc *nfc, uint reg, u32 bits)
{
        vf610_nfc_write(nfc, reg, vf610_nfc_read(nfc, reg) & ~bits);
}

static inline void vf610_nfc_set_field(struct vf610_nfc *nfc, u32 reg,
                                       u32 mask, u32 shift, u32 val)
{
        vf610_nfc_write(nfc, reg,
                        (vf610_nfc_read(nfc, reg) & (~mask)) | val << shift);
}

static inline bool vf610_nfc_kernel_is_little_endian(void)
{
#ifdef __LITTLE_ENDIAN
        return true;
#else
        return false;
#endif
}

/**
 * Read accessor for internal SRAM buffer
 * @dst: destination address in regular memory
 * @src: source address in SRAM buffer
 * @len: bytes to copy
 * @fix_endian: Fix endianness if required
 *
 * Use this accessor for the internal SRAM buffers. On the ARM
 * Freescale Vybrid SoC it's known that the driver can treat
 * the SRAM buffer as if it's memory. Other platform might need
 * to treat the buffers differently.
 *
 * The controller stores bytes from the NAND chip internally in big
 * endianness. On little endian platforms such as Vybrid this leads
 * to reversed byte order.
 * For performance reason (and earlier probably due to unawareness)
 * the driver avoids correcting endianness where it has control over
 * write and read side (e.g. page wise data access).
 */
static inline void vf610_nfc_rd_from_sram(void *dst, const void __iomem *src,
                                          size_t len, bool fix_endian)
{
        if (vf610_nfc_kernel_is_little_endian() && fix_endian) {
                unsigned int i;

                for (i = 0; i < len; i += 4) {
                        u32 val = swab32(__raw_readl(src + i));

                        memcpy(dst + i, &val, min(sizeof(val), len - i));
                }
        } else {
                memcpy_fromio(dst, src, len);
        }
}

/**
 * Write accessor for internal SRAM buffer
 * @dst: destination address in SRAM buffer
 * @src: source address in regular memory
 * @len: bytes to copy
 * @fix_endian: Fix endianness if required
 *
 * Use this accessor for the internal SRAM buffers. On the ARM
 * Freescale Vybrid SoC it's known that the driver can treat
 * the SRAM buffer as if it's memory. Other platform might need
 * to treat the buffers differently.
 *
 * The controller stores bytes from the NAND chip internally in big
 * endianness. On little endian platforms such as Vybrid this leads
 * to reversed byte order.
 * For performance reason (and earlier probably due to unawareness)
 * the driver avoids correcting endianness where it has control over
 * write and read side (e.g. page wise data access).
 */
static inline void vf610_nfc_wr_to_sram(void __iomem *dst, const void *src,
                                        size_t len, bool fix_endian)
{
        if (vf610_nfc_kernel_is_little_endian() && fix_endian) {
                unsigned int i;

                for (i = 0; i < len; i += 4) {
                        u32 val;

                        memcpy(&val, src + i, min(sizeof(val), len - i));
                        __raw_writel(swab32(val), dst + i);
                }
        } else {
                memcpy_toio(dst, src, len);
        }
}

/* Clear flags for upcoming command */
static inline void vf610_nfc_clear_status(struct vf610_nfc *nfc)
{
        u32 tmp = vf610_nfc_read(nfc, NFC_IRQ_STATUS);

        tmp |= CMD_DONE_CLEAR_BIT | IDLE_CLEAR_BIT;
        vf610_nfc_write(nfc, NFC_IRQ_STATUS, tmp);
}

static void vf610_nfc_done(struct vf610_nfc *nfc)
{
        unsigned long timeout = msecs_to_jiffies(100);

        /*
         * Barrier is needed after this write. This write need
         * to be done before reading the next register the first
         * time.
         * vf610_nfc_set implicates such a barrier by using writel
         * to write to the register.
         */
        vf610_nfc_set(nfc, NFC_IRQ_STATUS, IDLE_EN_BIT);
        vf610_nfc_set(nfc, NFC_FLASH_CMD2, START_BIT);

        if (!wait_for_completion_timeout(&nfc->cmd_done, timeout))
                dev_warn(nfc->dev, "Timeout while waiting for BUSY.\n");

        vf610_nfc_clear_status(nfc);
}

static irqreturn_t vf610_nfc_irq(int irq, void *data)
{
        struct vf610_nfc *nfc = data;

        vf610_nfc_clear(nfc, NFC_IRQ_STATUS, IDLE_EN_BIT);
        complete(&nfc->cmd_done);

        return IRQ_HANDLED;
}

static inline void vf610_nfc_ecc_mode(struct vf610_nfc *nfc, int ecc_mode)
{
        vf610_nfc_set_field(nfc, NFC_FLASH_CONFIG,
                            CONFIG_ECC_MODE_MASK,
                            CONFIG_ECC_MODE_SHIFT, ecc_mode);
}

static inline void vf610_nfc_transfer_size(struct vf610_nfc *nfc, int size)
{
        vf610_nfc_write(nfc, NFC_SECTOR_SIZE, size);
}

static inline void vf610_nfc_run(struct vf610_nfc *nfc, u32 col, u32 row,
                                 u32 cmd1, u32 cmd2, u32 trfr_sz)
{
        vf610_nfc_set_field(nfc, NFC_COL_ADDR, COL_ADDR_MASK,
                            COL_ADDR_SHIFT, col);

        vf610_nfc_set_field(nfc, NFC_ROW_ADDR, ROW_ADDR_MASK,
                            ROW_ADDR_SHIFT, row);

        vf610_nfc_write(nfc, NFC_SECTOR_SIZE, trfr_sz);
        vf610_nfc_write(nfc, NFC_FLASH_CMD1, cmd1);
        vf610_nfc_write(nfc, NFC_FLASH_CMD2, cmd2);

        dev_dbg(nfc->dev,
                "col 0x%04x, row 0x%08x, cmd1 0x%08x, cmd2 0x%08x, len %d\n",
                col, row, cmd1, cmd2, trfr_sz);

        vf610_nfc_done(nfc);
}

static inline const struct nand_op_instr *
vf610_get_next_instr(const struct nand_subop *subop, int *op_id)
{
        if (*op_id + 1 >= subop->ninstrs)
                return NULL;

        (*op_id)++;

        return &subop->instrs[*op_id];
}

static int vf610_nfc_cmd(struct nand_chip *chip,
                         const struct nand_subop *subop)
{
        const struct nand_op_instr *instr;
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        int op_id = -1, trfr_sz = 0, offset = 0;
        u32 col = 0, row = 0, cmd1 = 0, cmd2 = 0, code = 0;
        bool force8bit = false;

        /*
         * Some ops are optional, but the hardware requires the operations
         * to be in this exact order.
         * The op parser enforces the order and makes sure that there isn't
         * a read and write element in a single operation.
         */
        instr = vf610_get_next_instr(subop, &op_id);
        if (!instr)
                return -EINVAL;

        if (instr && instr->type == NAND_OP_CMD_INSTR) {
                cmd2 |= instr->ctx.cmd.opcode << CMD_BYTE1_SHIFT;
                code |= COMMAND_CMD_BYTE1;

                instr = vf610_get_next_instr(subop, &op_id);
        }

        if (instr && instr->type == NAND_OP_ADDR_INSTR) {
                int naddrs = nand_subop_get_num_addr_cyc(subop, op_id);
                int i = nand_subop_get_addr_start_off(subop, op_id);

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

                        if (i < 2)
                                col |= COL_ADDR(i, val);
                        else
                                row |= ROW_ADDR(i - 2, val);
                }
                code |= COMMAND_NADDR_BYTES(naddrs);

                instr = vf610_get_next_instr(subop, &op_id);
        }

        if (instr && instr->type == NAND_OP_DATA_OUT_INSTR) {
                trfr_sz = nand_subop_get_data_len(subop, op_id);
                offset = nand_subop_get_data_start_off(subop, op_id);
                force8bit = instr->ctx.data.force_8bit;

                /*
                 * Don't fix endianness on page access for historical reasons.
                 * See comment in vf610_nfc_wr_to_sram
                 */
                vf610_nfc_wr_to_sram(nfc->regs + NFC_MAIN_AREA(0) + offset,
                                     instr->ctx.data.buf.out + offset,
                                     trfr_sz, !nfc->data_access);
                code |= COMMAND_WRITE_DATA;

                instr = vf610_get_next_instr(subop, &op_id);
        }

        if (instr && instr->type == NAND_OP_CMD_INSTR) {
                cmd1 |= instr->ctx.cmd.opcode << CMD_BYTE2_SHIFT;
                code |= COMMAND_CMD_BYTE2;

                instr = vf610_get_next_instr(subop, &op_id);
        }

        if (instr && instr->type == NAND_OP_WAITRDY_INSTR) {
                code |= COMMAND_RB_HANDSHAKE;

                instr = vf610_get_next_instr(subop, &op_id);
        }

        if (instr && instr->type == NAND_OP_DATA_IN_INSTR) {
                trfr_sz = nand_subop_get_data_len(subop, op_id);
                offset = nand_subop_get_data_start_off(subop, op_id);
                force8bit = instr->ctx.data.force_8bit;

                code |= COMMAND_READ_DATA;
        }

        if (force8bit && (chip->options & NAND_BUSWIDTH_16))
                vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT);

        cmd2 |= code << CMD_CODE_SHIFT;

        vf610_nfc_run(nfc, col, row, cmd1, cmd2, trfr_sz);

        if (instr && instr->type == NAND_OP_DATA_IN_INSTR) {
                /*
                 * Don't fix endianness on page access for historical reasons.
                 * See comment in vf610_nfc_rd_from_sram
                 */
                vf610_nfc_rd_from_sram(instr->ctx.data.buf.in + offset,
                                       nfc->regs + NFC_MAIN_AREA(0) + offset,
                                       trfr_sz, !nfc->data_access);
        }

        if (force8bit && (chip->options & NAND_BUSWIDTH_16))
                vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT);

        return 0;
}

static const struct nand_op_parser vf610_nfc_op_parser = NAND_OP_PARSER(
        NAND_OP_PARSER_PATTERN(vf610_nfc_cmd,
                NAND_OP_PARSER_PAT_CMD_ELEM(true),
                NAND_OP_PARSER_PAT_ADDR_ELEM(true, 5),
                NAND_OP_PARSER_PAT_DATA_OUT_ELEM(true, PAGE_2K + OOB_MAX),
                NAND_OP_PARSER_PAT_CMD_ELEM(true),
                NAND_OP_PARSER_PAT_WAITRDY_ELEM(true)),
        NAND_OP_PARSER_PATTERN(vf610_nfc_cmd,
                NAND_OP_PARSER_PAT_CMD_ELEM(true),
                NAND_OP_PARSER_PAT_ADDR_ELEM(true, 5),
                NAND_OP_PARSER_PAT_CMD_ELEM(true),
                NAND_OP_PARSER_PAT_WAITRDY_ELEM(true),
                NAND_OP_PARSER_PAT_DATA_IN_ELEM(true, PAGE_2K + OOB_MAX)),
        );

/*
 * This function supports Vybrid only (MPC5125 would have full RB and four CS)
 */
static void vf610_nfc_select_target(struct nand_chip *chip, unsigned int cs)
{
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        u32 tmp;

        /* Vybrid only (MPC5125 would have full RB and four CS) */
        if (nfc->variant != NFC_VFC610)
                return;

        tmp = vf610_nfc_read(nfc, NFC_ROW_ADDR);
        tmp &= ~(ROW_ADDR_CHIP_SEL_RB_MASK | ROW_ADDR_CHIP_SEL_MASK);
        tmp |= 1 << ROW_ADDR_CHIP_SEL_RB_SHIFT;
        tmp |= BIT(cs) << ROW_ADDR_CHIP_SEL_SHIFT;

        vf610_nfc_write(nfc, NFC_ROW_ADDR, tmp);
}

static int vf610_nfc_exec_op(struct nand_chip *chip,
                             const struct nand_operation *op,
                             bool check_only)
{
        vf610_nfc_select_target(chip, op->cs);
        return nand_op_parser_exec_op(chip, &vf610_nfc_op_parser, op,
                                      check_only);
}

static inline int vf610_nfc_correct_data(struct nand_chip *chip, uint8_t *dat,
                                         uint8_t *oob, int page)
{
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        struct mtd_info *mtd = nand_to_mtd(chip);
        u32 ecc_status_off = NFC_MAIN_AREA(0) + ECC_SRAM_ADDR + ECC_STATUS;
        u8 ecc_status;
        u8 ecc_count;
        int flips_threshold = nfc->chip.ecc.strength / 2;

        ecc_status = vf610_nfc_read(nfc, ecc_status_off) & 0xff;
        ecc_count = ecc_status & ECC_STATUS_ERR_COUNT;

        if (!(ecc_status & ECC_STATUS_MASK))
                return ecc_count;

        nfc->data_access = true;
        nand_read_oob_op(&nfc->chip, page, 0, oob, mtd->oobsize);
        nfc->data_access = false;

        /*
         * On an erased page, bit count (including OOB) should be zero or
         * at least less then half of the ECC strength.
         */
        return nand_check_erased_ecc_chunk(dat, nfc->chip.ecc.size, oob,
                                           mtd->oobsize, NULL, 0,
                                           flips_threshold);
}

static void vf610_nfc_fill_row(struct nand_chip *chip, int page, u32 *code,
                               u32 *row)
{
        *row = ROW_ADDR(0, page & 0xff) | ROW_ADDR(1, page >> 8);
        *code |= COMMAND_RAR_BYTE1 | COMMAND_RAR_BYTE2;

        if (chip->options & NAND_ROW_ADDR_3) {
                *row |= ROW_ADDR(2, page >> 16);
                *code |= COMMAND_RAR_BYTE3;
        }
}

static int vf610_nfc_read_page(struct nand_chip *chip, uint8_t *buf,
                               int oob_required, int page)
{
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        struct mtd_info *mtd = nand_to_mtd(chip);
        int trfr_sz = mtd->writesize + mtd->oobsize;
        u32 row = 0, cmd1 = 0, cmd2 = 0, code = 0;
        int stat;

        vf610_nfc_select_target(chip, chip->cur_cs);

        cmd2 |= NAND_CMD_READ0 << CMD_BYTE1_SHIFT;
        code |= COMMAND_CMD_BYTE1 | COMMAND_CAR_BYTE1 | COMMAND_CAR_BYTE2;

        vf610_nfc_fill_row(chip, page, &code, &row);

        cmd1 |= NAND_CMD_READSTART << CMD_BYTE2_SHIFT;
        code |= COMMAND_CMD_BYTE2 | COMMAND_RB_HANDSHAKE | COMMAND_READ_DATA;

        cmd2 |= code << CMD_CODE_SHIFT;

        vf610_nfc_ecc_mode(nfc, nfc->ecc_mode);
        vf610_nfc_run(nfc, 0, row, cmd1, cmd2, trfr_sz);
        vf610_nfc_ecc_mode(nfc, ECC_BYPASS);

        /*
         * Don't fix endianness on page access for historical reasons.
         * See comment in vf610_nfc_rd_from_sram
         */
        vf610_nfc_rd_from_sram(buf, nfc->regs + NFC_MAIN_AREA(0),
                               mtd->writesize, false);
        if (oob_required)
                vf610_nfc_rd_from_sram(chip->oob_poi,
                                       nfc->regs + NFC_MAIN_AREA(0) +
                                                   mtd->writesize,
                                       mtd->oobsize, false);

        stat = vf610_nfc_correct_data(chip, buf, chip->oob_poi, page);

        if (stat < 0) {
                mtd->ecc_stats.failed++;
                return 0;
        } else {
                mtd->ecc_stats.corrected += stat;
                return stat;
        }
}

static int vf610_nfc_write_page(struct nand_chip *chip, const uint8_t *buf,
                                int oob_required, int page)
{
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        struct mtd_info *mtd = nand_to_mtd(chip);
        int trfr_sz = mtd->writesize + mtd->oobsize;
        u32 row = 0, cmd1 = 0, cmd2 = 0, code = 0;
        u8 status;
        int ret;

        vf610_nfc_select_target(chip, chip->cur_cs);

        cmd2 |= NAND_CMD_SEQIN << CMD_BYTE1_SHIFT;
        code |= COMMAND_CMD_BYTE1 | COMMAND_CAR_BYTE1 | COMMAND_CAR_BYTE2;

        vf610_nfc_fill_row(chip, page, &code, &row);

        cmd1 |= NAND_CMD_PAGEPROG << CMD_BYTE2_SHIFT;
        code |= COMMAND_CMD_BYTE2 | COMMAND_WRITE_DATA;

        /*
         * Don't fix endianness on page access for historical reasons.
         * See comment in vf610_nfc_wr_to_sram
         */
        vf610_nfc_wr_to_sram(nfc->regs + NFC_MAIN_AREA(0), buf,
                             mtd->writesize, false);

        code |= COMMAND_RB_HANDSHAKE;
        cmd2 |= code << CMD_CODE_SHIFT;

        vf610_nfc_ecc_mode(nfc, nfc->ecc_mode);
        vf610_nfc_run(nfc, 0, row, cmd1, cmd2, trfr_sz);
        vf610_nfc_ecc_mode(nfc, ECC_BYPASS);

        ret = nand_status_op(chip, &status);
        if (ret)
                return ret;

        if (status & NAND_STATUS_FAIL)
                return -EIO;

        return 0;
}

static int vf610_nfc_read_page_raw(struct nand_chip *chip, u8 *buf,
                                   int oob_required, int page)
{
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        int ret;

        nfc->data_access = true;
        ret = nand_read_page_raw(chip, buf, oob_required, page);
        nfc->data_access = false;

        return ret;
}

static int vf610_nfc_write_page_raw(struct nand_chip *chip, const u8 *buf,
                                    int oob_required, int page)
{
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret;

        nfc->data_access = true;
        ret = nand_prog_page_begin_op(chip, page, 0, buf, mtd->writesize);
        if (!ret && oob_required)
                ret = nand_write_data_op(chip, chip->oob_poi, mtd->oobsize,
                                         false);
        nfc->data_access = false;

        if (ret)
                return ret;

        return nand_prog_page_end_op(chip);
}

static int vf610_nfc_read_oob(struct nand_chip *chip, int page)
{
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        int ret;

        nfc->data_access = true;
        ret = nand_read_oob_std(chip, page);
        nfc->data_access = false;

        return ret;
}

static int vf610_nfc_write_oob(struct nand_chip *chip, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        struct vf610_nfc *nfc = chip_to_nfc(chip);
        int ret;

        nfc->data_access = true;
        ret = nand_prog_page_begin_op(chip, page, mtd->writesize,
                                      chip->oob_poi, mtd->oobsize);
        nfc->data_access = false;

        if (ret)
                return ret;

        return nand_prog_page_end_op(chip);
}

static const struct of_device_id vf610_nfc_dt_ids[] = {
        { .compatible = "fsl,vf610-nfc", .data = (void *)NFC_VFC610 },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, vf610_nfc_dt_ids);

static void vf610_nfc_preinit_controller(struct vf610_nfc *nfc)
{
        vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT);
        vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_ADDR_AUTO_INCR_BIT);
        vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_BUFNO_AUTO_INCR_BIT);
        vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_BOOT_MODE_BIT);
        vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_DMA_REQ_BIT);
        vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_FAST_FLASH_BIT);
        vf610_nfc_ecc_mode(nfc, ECC_BYPASS);

        /* Disable virtual pages, only one elementary transfer unit */
        vf610_nfc_set_field(nfc, NFC_FLASH_CONFIG, CONFIG_PAGE_CNT_MASK,
                            CONFIG_PAGE_CNT_SHIFT, 1);
}

static void vf610_nfc_init_controller(struct vf610_nfc *nfc)
{
        if (nfc->chip.options & NAND_BUSWIDTH_16)
                vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT);
        else
                vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT);

        if (nfc->chip.ecc.mode == NAND_ECC_HW) {
                /* Set ECC status offset in SRAM */
                vf610_nfc_set_field(nfc, NFC_FLASH_CONFIG,
                                    CONFIG_ECC_SRAM_ADDR_MASK,
                                    CONFIG_ECC_SRAM_ADDR_SHIFT,
                                    ECC_SRAM_ADDR >> 3);

                /* Enable ECC status in SRAM */
                vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_ECC_SRAM_REQ_BIT);
        }
}

static int vf610_nfc_attach_chip(struct nand_chip *chip)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        struct vf610_nfc *nfc = chip_to_nfc(chip);

        vf610_nfc_init_controller(nfc);

        /* Bad block options. */
        if (chip->bbt_options & NAND_BBT_USE_FLASH)
                chip->bbt_options |= NAND_BBT_NO_OOB;

        /* Single buffer only, max 256 OOB minus ECC status */
        if (mtd->writesize + mtd->oobsize > PAGE_2K + OOB_MAX - 8) {
                dev_err(nfc->dev, "Unsupported flash page size\n");
                return -ENXIO;
        }

        if (chip->ecc.mode != NAND_ECC_HW)
                return 0;

        if (mtd->writesize != PAGE_2K && mtd->oobsize < 64) {
                dev_err(nfc->dev, "Unsupported flash with hwecc\n");
                return -ENXIO;
        }

        if (chip->ecc.size != mtd->writesize) {
                dev_err(nfc->dev, "Step size needs to be page size\n");
                return -ENXIO;
        }

        /* Only 64 byte ECC layouts known */
        if (mtd->oobsize > 64)
                mtd->oobsize = 64;

        /* Use default large page ECC layout defined in NAND core */
        mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
        if (chip->ecc.strength == 32) {
                nfc->ecc_mode = ECC_60_BYTE;
                chip->ecc.bytes = 60;
        } else if (chip->ecc.strength == 24) {
                nfc->ecc_mode = ECC_45_BYTE;
                chip->ecc.bytes = 45;
        } else {
                dev_err(nfc->dev, "Unsupported ECC strength\n");
                return -ENXIO;
        }

        chip->ecc.read_page = vf610_nfc_read_page;
        chip->ecc.write_page = vf610_nfc_write_page;
        chip->ecc.read_page_raw = vf610_nfc_read_page_raw;
        chip->ecc.write_page_raw = vf610_nfc_write_page_raw;
        chip->ecc.read_oob = vf610_nfc_read_oob;
        chip->ecc.write_oob = vf610_nfc_write_oob;

        chip->ecc.size = PAGE_2K;

        return 0;
}

static const struct nand_controller_ops vf610_nfc_controller_ops = {
        .attach_chip = vf610_nfc_attach_chip,
        .exec_op = vf610_nfc_exec_op,

};

static int vf610_nfc_probe(struct platform_device *pdev)
{
        struct vf610_nfc *nfc;
        struct resource *res;
        struct mtd_info *mtd;
        struct nand_chip *chip;
        struct device_node *child;
        const struct of_device_id *of_id;
        int err;
        int irq;

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

        nfc->dev = &pdev->dev;
        chip = &nfc->chip;
        mtd = nand_to_mtd(chip);

        mtd->owner = THIS_MODULE;
        mtd->dev.parent = nfc->dev;
        mtd->name = DRV_NAME;

        irq = platform_get_irq(pdev, 0);
        if (irq <= 0)
                return -EINVAL;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        nfc->regs = devm_ioremap_resource(nfc->dev, res);
        if (IS_ERR(nfc->regs))
                return PTR_ERR(nfc->regs);

        nfc->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(nfc->clk))
                return PTR_ERR(nfc->clk);

        err = clk_prepare_enable(nfc->clk);
        if (err) {
                dev_err(nfc->dev, "Unable to enable clock!\n");
                return err;
        }

        of_id = of_match_device(vf610_nfc_dt_ids, &pdev->dev);
        if (!of_id)
                return -ENODEV;

        nfc->variant = (enum vf610_nfc_variant)of_id->data;

        for_each_available_child_of_node(nfc->dev->of_node, child) {
                if (of_device_is_compatible(child, "fsl,vf610-nfc-nandcs")) {

                        if (nand_get_flash_node(chip)) {
                                dev_err(nfc->dev,
                                        "Only one NAND chip supported!\n");
                                err = -EINVAL;
                                goto err_disable_clk;
                        }

                        nand_set_flash_node(chip, child);
                }
        }

        if (!nand_get_flash_node(chip)) {
                dev_err(nfc->dev, "NAND chip sub-node missing!\n");
                err = -ENODEV;
                goto err_disable_clk;
        }

        chip->options |= NAND_NO_SUBPAGE_WRITE;

        init_completion(&nfc->cmd_done);

        err = devm_request_irq(nfc->dev, irq, vf610_nfc_irq, 0, DRV_NAME, nfc);
        if (err) {
                dev_err(nfc->dev, "Error requesting IRQ!\n");
                goto err_disable_clk;
        }

        vf610_nfc_preinit_controller(nfc);

        nand_controller_init(&nfc->base);
        nfc->base.ops = &vf610_nfc_controller_ops;
        chip->controller = &nfc->base;

        /* Scan the NAND chip */
        err = nand_scan(chip, 1);
        if (err)
                goto err_disable_clk;

        platform_set_drvdata(pdev, nfc);

        /* Register device in MTD */
        err = mtd_device_register(mtd, NULL, 0);
        if (err)
                goto err_cleanup_nand;
        return 0;

err_cleanup_nand:
        nand_cleanup(chip);
err_disable_clk:
        clk_disable_unprepare(nfc->clk);
        return err;
}

static int vf610_nfc_remove(struct platform_device *pdev)
{
        struct vf610_nfc *nfc = platform_get_drvdata(pdev);

        nand_release(&nfc->chip);
        clk_disable_unprepare(nfc->clk);
        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int vf610_nfc_suspend(struct device *dev)
{
        struct vf610_nfc *nfc = dev_get_drvdata(dev);

        clk_disable_unprepare(nfc->clk);
        return 0;
}

static int vf610_nfc_resume(struct device *dev)
{
        struct vf610_nfc *nfc = dev_get_drvdata(dev);
        int err;

        err = clk_prepare_enable(nfc->clk);
        if (err)
                return err;

        vf610_nfc_preinit_controller(nfc);
        vf610_nfc_init_controller(nfc);
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(vf610_nfc_pm_ops, vf610_nfc_suspend, vf610_nfc_resume);

static struct platform_driver vf610_nfc_driver = {
        .driver         = {
                .name   = DRV_NAME,
                .of_match_table = vf610_nfc_dt_ids,
                .pm     = &vf610_nfc_pm_ops,
        },
        .probe          = vf610_nfc_probe,
        .remove         = vf610_nfc_remove,
};

module_platform_driver(vf610_nfc_driver);

MODULE_AUTHOR("Stefan Agner <stefan.agner@toradex.com>");
MODULE_DESCRIPTION("Freescale VF610/MPC5125 NFC MTD NAND driver");
MODULE_LICENSE("GPL");