/*
 * NAND Flash Controller Device Driver
 * Copyright © 2009-2010, Intel Corporation and its suppliers.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/module.h>

#include "denali.h"

MODULE_LICENSE("GPL");

/*
 * We define a module parameter that allows the user to override
 * the hardware and decide what timing mode should be used.
 */
#define NAND_DEFAULT_TIMINGS    -1

static int onfi_timing_mode = NAND_DEFAULT_TIMINGS;
module_param(onfi_timing_mode, int, S_IRUGO);
MODULE_PARM_DESC(onfi_timing_mode,
           "Overrides default ONFI setting. -1 indicates use default timings");

#define DENALI_NAND_NAME    "denali-nand"

/*
 * We define a macro here that combines all interrupts this driver uses into
 * a single constant value, for convenience.
 */
#define DENALI_IRQ_ALL  (INTR_STATUS__DMA_CMD_COMP | \
                        INTR_STATUS__ECC_TRANSACTION_DONE | \
                        INTR_STATUS__ECC_ERR | \
                        INTR_STATUS__PROGRAM_FAIL | \
                        INTR_STATUS__LOAD_COMP | \
                        INTR_STATUS__PROGRAM_COMP | \
                        INTR_STATUS__TIME_OUT | \
                        INTR_STATUS__ERASE_FAIL | \
                        INTR_STATUS__RST_COMP | \
                        INTR_STATUS__ERASE_COMP)

/*
 * indicates whether or not the internal value for the flash bank is
 * valid or not
 */
#define CHIP_SELECT_INVALID     -1

#define SUPPORT_8BITECC         1

/*
 * This macro divides two integers and rounds fractional values up
 * to the nearest integer value.
 */
#define CEIL_DIV(X, Y) (((X)%(Y)) ? ((X)/(Y)+1) : ((X)/(Y)))

/*
 * this macro allows us to convert from an MTD structure to our own
 * device context (denali) structure.
 */
#define mtd_to_denali(m) container_of(m, struct denali_nand_info, mtd)

/*
 * These constants are defined by the driver to enable common driver
 * configuration options.
 */
#define SPARE_ACCESS            0x41
#define MAIN_ACCESS             0x42
#define MAIN_SPARE_ACCESS       0x43
#define PIPELINE_ACCESS         0x2000

#define DENALI_READ     0
#define DENALI_WRITE    0x100

/* types of device accesses. We can issue commands and get status */
#define COMMAND_CYCLE   0
#define ADDR_CYCLE      1
#define STATUS_CYCLE    2

/*
 * this is a helper macro that allows us to
 * format the bank into the proper bits for the controller
 */
#define BANK(x) ((x) << 24)

/* forward declarations */
static void clear_interrupts(struct denali_nand_info *denali);
static uint32_t wait_for_irq(struct denali_nand_info *denali,
                                                        uint32_t irq_mask);
static void denali_irq_enable(struct denali_nand_info *denali,
                                                        uint32_t int_mask);
static uint32_t read_interrupt_status(struct denali_nand_info *denali);

/*
 * Certain operations for the denali NAND controller use an indexed mode to
 * read/write data. The operation is performed by writing the address value
 * of the command to the device memory followed by the data. This function
 * abstracts this common operation.
 */
static void index_addr(struct denali_nand_info *denali,
                                uint32_t address, uint32_t data)
{
        iowrite32(address, denali->flash_mem);
        iowrite32(data, denali->flash_mem + 0x10);
}

/* Perform an indexed read of the device */
static void index_addr_read_data(struct denali_nand_info *denali,
                                 uint32_t address, uint32_t *pdata)
{
        iowrite32(address, denali->flash_mem);
        *pdata = ioread32(denali->flash_mem + 0x10);
}

/*
 * We need to buffer some data for some of the NAND core routines.
 * The operations manage buffering that data.
 */
static void reset_buf(struct denali_nand_info *denali)
{
        denali->buf.head = denali->buf.tail = 0;
}

static void write_byte_to_buf(struct denali_nand_info *denali, uint8_t byte)
{
        denali->buf.buf[denali->buf.tail++] = byte;
}

/* reads the status of the device */
static void read_status(struct denali_nand_info *denali)
{
        uint32_t cmd;

        /* initialize the data buffer to store status */
        reset_buf(denali);

        cmd = ioread32(denali->flash_reg + WRITE_PROTECT);
        if (cmd)
                write_byte_to_buf(denali, NAND_STATUS_WP);
        else
                write_byte_to_buf(denali, 0);
}

/* resets a specific device connected to the core */
static void reset_bank(struct denali_nand_info *denali)
{
        uint32_t irq_status;
        uint32_t irq_mask = INTR_STATUS__RST_COMP | INTR_STATUS__TIME_OUT;

        clear_interrupts(denali);

        iowrite32(1 << denali->flash_bank, denali->flash_reg + DEVICE_RESET);

        irq_status = wait_for_irq(denali, irq_mask);

        if (irq_status & INTR_STATUS__TIME_OUT)
                dev_err(denali->dev, "reset bank failed.\n");
}

/* Reset the flash controller */
static uint16_t denali_nand_reset(struct denali_nand_info *denali)
{
        int i;

        dev_dbg(denali->dev, "%s, Line %d, Function: %s\n",
                __FILE__, __LINE__, __func__);

        for (i = 0; i < denali->max_banks; i++)
                iowrite32(INTR_STATUS__RST_COMP | INTR_STATUS__TIME_OUT,
                denali->flash_reg + INTR_STATUS(i));

        for (i = 0; i < denali->max_banks; i++) {
                iowrite32(1 << i, denali->flash_reg + DEVICE_RESET);
                while (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &
                        (INTR_STATUS__RST_COMP | INTR_STATUS__TIME_OUT)))
                        cpu_relax();
                if (ioread32(denali->flash_reg + INTR_STATUS(i)) &
                        INTR_STATUS__TIME_OUT)
                        dev_dbg(denali->dev,
                        "NAND Reset operation timed out on bank %d\n", i);
        }

        for (i = 0; i < denali->max_banks; i++)
                iowrite32(INTR_STATUS__RST_COMP | INTR_STATUS__TIME_OUT,
                          denali->flash_reg + INTR_STATUS(i));

        return PASS;
}

/*
 * this routine calculates the ONFI timing values for a given mode and
 * programs the clocking register accordingly. The mode is determined by
 * the get_onfi_nand_para routine.
 */
static void nand_onfi_timing_set(struct denali_nand_info *denali,
                                                                uint16_t mode)
{
        uint16_t Trea[6] = {40, 30, 25, 20, 20, 16};
        uint16_t Trp[6] = {50, 25, 17, 15, 12, 10};
        uint16_t Treh[6] = {30, 15, 15, 10, 10, 7};
        uint16_t Trc[6] = {100, 50, 35, 30, 25, 20};
        uint16_t Trhoh[6] = {0, 15, 15, 15, 15, 15};
        uint16_t Trloh[6] = {0, 0, 0, 0, 5, 5};
        uint16_t Tcea[6] = {100, 45, 30, 25, 25, 25};
        uint16_t Tadl[6] = {200, 100, 100, 100, 70, 70};
        uint16_t Trhw[6] = {200, 100, 100, 100, 100, 100};
        uint16_t Trhz[6] = {200, 100, 100, 100, 100, 100};
        uint16_t Twhr[6] = {120, 80, 80, 60, 60, 60};
        uint16_t Tcs[6] = {70, 35, 25, 25, 20, 15};

        uint16_t data_invalid_rhoh, data_invalid_rloh, data_invalid;
        uint16_t dv_window = 0;
        uint16_t en_lo, en_hi;
        uint16_t acc_clks;
        uint16_t addr_2_data, re_2_we, re_2_re, we_2_re, cs_cnt;

        dev_dbg(denali->dev, "%s, Line %d, Function: %s\n",
                __FILE__, __LINE__, __func__);

        en_lo = CEIL_DIV(Trp[mode], CLK_X);
        en_hi = CEIL_DIV(Treh[mode], CLK_X);
#if ONFI_BLOOM_TIME
        if ((en_hi * CLK_X) < (Treh[mode] + 2))
                en_hi++;
#endif

        if ((en_lo + en_hi) * CLK_X < Trc[mode])
                en_lo += CEIL_DIV((Trc[mode] - (en_lo + en_hi) * CLK_X), CLK_X);

        if ((en_lo + en_hi) < CLK_MULTI)
                en_lo += CLK_MULTI - en_lo - en_hi;

        while (dv_window < 8) {
                data_invalid_rhoh = en_lo * CLK_X + Trhoh[mode];

                data_invalid_rloh = (en_lo + en_hi) * CLK_X + Trloh[mode];

                data_invalid = data_invalid_rhoh < data_invalid_rloh ?
                                        data_invalid_rhoh : data_invalid_rloh;

                dv_window = data_invalid - Trea[mode];

                if (dv_window < 8)
                        en_lo++;
        }

        acc_clks = CEIL_DIV(Trea[mode], CLK_X);

        while (acc_clks * CLK_X - Trea[mode] < 3)
                acc_clks++;

        if (data_invalid - acc_clks * CLK_X < 2)
                dev_warn(denali->dev, "%s, Line %d: Warning!\n",
                         __FILE__, __LINE__);

        addr_2_data = CEIL_DIV(Tadl[mode], CLK_X);
        re_2_we = CEIL_DIV(Trhw[mode], CLK_X);
        re_2_re = CEIL_DIV(Trhz[mode], CLK_X);
        we_2_re = CEIL_DIV(Twhr[mode], CLK_X);
        cs_cnt = CEIL_DIV((Tcs[mode] - Trp[mode]), CLK_X);
        if (cs_cnt == 0)
                cs_cnt = 1;

        if (Tcea[mode]) {
                while (cs_cnt * CLK_X + Trea[mode] < Tcea[mode])
                        cs_cnt++;
        }

#if MODE5_WORKAROUND
        if (mode == 5)
                acc_clks = 5;
#endif

        /* Sighting 3462430: Temporary hack for MT29F128G08CJABAWP:B */
        if (ioread32(denali->flash_reg + MANUFACTURER_ID) == 0 &&
                ioread32(denali->flash_reg + DEVICE_ID) == 0x88)
                acc_clks = 6;

        iowrite32(acc_clks, denali->flash_reg + ACC_CLKS);
        iowrite32(re_2_we, denali->flash_reg + RE_2_WE);
        iowrite32(re_2_re, denali->flash_reg + RE_2_RE);
        iowrite32(we_2_re, denali->flash_reg + WE_2_RE);
        iowrite32(addr_2_data, denali->flash_reg + ADDR_2_DATA);
        iowrite32(en_lo, denali->flash_reg + RDWR_EN_LO_CNT);
        iowrite32(en_hi, denali->flash_reg + RDWR_EN_HI_CNT);
        iowrite32(cs_cnt, denali->flash_reg + CS_SETUP_CNT);
}

/* queries the NAND device to see what ONFI modes it supports. */
static uint16_t get_onfi_nand_para(struct denali_nand_info *denali)
{
        int i;

        /*
         * we needn't to do a reset here because driver has already
         * reset all the banks before
         */
        if (!(ioread32(denali->flash_reg + ONFI_TIMING_MODE) &
                ONFI_TIMING_MODE__VALUE))
                return FAIL;

        for (i = 5; i > 0; i--) {
                if (ioread32(denali->flash_reg + ONFI_TIMING_MODE) &
                        (0x01 << i))
                        break;
        }

        nand_onfi_timing_set(denali, i);

        /*
         * By now, all the ONFI devices we know support the page cache
         * rw feature. So here we enable the pipeline_rw_ahead feature
         */
        /* iowrite32(1, denali->flash_reg + CACHE_WRITE_ENABLE); */
        /* iowrite32(1, denali->flash_reg + CACHE_READ_ENABLE);  */

        return PASS;
}

static void get_samsung_nand_para(struct denali_nand_info *denali,
                                                        uint8_t device_id)
{
        if (device_id == 0xd3) { /* Samsung K9WAG08U1A */
                /* Set timing register values according to datasheet */
                iowrite32(5, denali->flash_reg + ACC_CLKS);
                iowrite32(20, denali->flash_reg + RE_2_WE);
                iowrite32(12, denali->flash_reg + WE_2_RE);
                iowrite32(14, denali->flash_reg + ADDR_2_DATA);
                iowrite32(3, denali->flash_reg + RDWR_EN_LO_CNT);
                iowrite32(2, denali->flash_reg + RDWR_EN_HI_CNT);
                iowrite32(2, denali->flash_reg + CS_SETUP_CNT);
        }
}

static void get_toshiba_nand_para(struct denali_nand_info *denali)
{
        uint32_t tmp;

        /*
         * Workaround to fix a controller bug which reports a wrong
         * spare area size for some kind of Toshiba NAND device
         */
        if ((ioread32(denali->flash_reg + DEVICE_MAIN_AREA_SIZE) == 4096) &&
                (ioread32(denali->flash_reg + DEVICE_SPARE_AREA_SIZE) == 64)) {
                iowrite32(216, denali->flash_reg + DEVICE_SPARE_AREA_SIZE);
                tmp = ioread32(denali->flash_reg + DEVICES_CONNECTED) *
                        ioread32(denali->flash_reg + DEVICE_SPARE_AREA_SIZE);
                iowrite32(tmp,
                                denali->flash_reg + LOGICAL_PAGE_SPARE_SIZE);
#if SUPPORT_15BITECC
                iowrite32(15, denali->flash_reg + ECC_CORRECTION);
#elif SUPPORT_8BITECC
                iowrite32(8, denali->flash_reg + ECC_CORRECTION);
#endif
        }
}

static void get_hynix_nand_para(struct denali_nand_info *denali,
                                                        uint8_t device_id)
{
        uint32_t main_size, spare_size;

        switch (device_id) {
        case 0xD5: /* Hynix H27UAG8T2A, H27UBG8U5A or H27UCG8VFA */
        case 0xD7: /* Hynix H27UDG8VEM, H27UCG8UDM or H27UCG8V5A */
                iowrite32(128, denali->flash_reg + PAGES_PER_BLOCK);
                iowrite32(4096, denali->flash_reg + DEVICE_MAIN_AREA_SIZE);
                iowrite32(224, denali->flash_reg + DEVICE_SPARE_AREA_SIZE);
                main_size = 4096 *
                        ioread32(denali->flash_reg + DEVICES_CONNECTED);
                spare_size = 224 *
                        ioread32(denali->flash_reg + DEVICES_CONNECTED);
                iowrite32(main_size,
                                denali->flash_reg + LOGICAL_PAGE_DATA_SIZE);
                iowrite32(spare_size,
                                denali->flash_reg + LOGICAL_PAGE_SPARE_SIZE);
                iowrite32(0, denali->flash_reg + DEVICE_WIDTH);
#if SUPPORT_15BITECC
                iowrite32(15, denali->flash_reg + ECC_CORRECTION);
#elif SUPPORT_8BITECC
                iowrite32(8, denali->flash_reg + ECC_CORRECTION);
#endif
                break;
        default:
                dev_warn(denali->dev,
                         "Spectra: Unknown Hynix NAND (Device ID: 0x%x).\n"
                         "Will use default parameter values instead.\n",
                         device_id);
        }
}

/*
 * determines how many NAND chips are connected to the controller. Note for
 * Intel CE4100 devices we don't support more than one device.
 */
static void find_valid_banks(struct denali_nand_info *denali)
{
        uint32_t id[denali->max_banks];
        int i;

        denali->total_used_banks = 1;
        for (i = 0; i < denali->max_banks; i++) {
                index_addr(denali, MODE_11 | (i << 24) | 0, 0x90);
                index_addr(denali, MODE_11 | (i << 24) | 1, 0);
                index_addr_read_data(denali, MODE_11 | (i << 24) | 2, &id[i]);

                dev_dbg(denali->dev,
                        "Return 1st ID for bank[%d]: %x\n", i, id[i]);

                if (i == 0) {
                        if (!(id[i] & 0x0ff))
                                break; /* WTF? */
                } else {
                        if ((id[i] & 0x0ff) == (id[0] & 0x0ff))
                                denali->total_used_banks++;
                        else
                                break;
                }
        }

        if (denali->platform == INTEL_CE4100) {
                /*
                 * Platform limitations of the CE4100 device limit
                 * users to a single chip solution for NAND.
                 * Multichip support is not enabled.
                 */
                if (denali->total_used_banks != 1) {
                        dev_err(denali->dev,
                                "Sorry, Intel CE4100 only supports a single NAND device.\n");
                        BUG();
                }
        }
        dev_dbg(denali->dev,
                "denali->total_used_banks: %d\n", denali->total_used_banks);
}

/*
 * Use the configuration feature register to determine the maximum number of
 * banks that the hardware supports.
 */
static void detect_max_banks(struct denali_nand_info *denali)
{
        uint32_t features = ioread32(denali->flash_reg + FEATURES);

        denali->max_banks = 2 << (features & FEATURES__N_BANKS);
}

static void detect_partition_feature(struct denali_nand_info *denali)
{
        /*
         * For MRST platform, denali->fwblks represent the
         * number of blocks firmware is taken,
         * FW is in protect partition and MTD driver has no
         * permission to access it. So let driver know how many
         * blocks it can't touch.
         */
        if (ioread32(denali->flash_reg + FEATURES) & FEATURES__PARTITION) {
                if ((ioread32(denali->flash_reg + PERM_SRC_ID(1)) &
                        PERM_SRC_ID__SRCID) == SPECTRA_PARTITION_ID) {
                        denali->fwblks =
                            ((ioread32(denali->flash_reg + MIN_MAX_BANK(1)) &
                              MIN_MAX_BANK__MIN_VALUE) *
                             denali->blksperchip)
                            +
                            (ioread32(denali->flash_reg + MIN_BLK_ADDR(1)) &
                            MIN_BLK_ADDR__VALUE);
                } else {
                        denali->fwblks = SPECTRA_START_BLOCK;
                }
        } else {
                denali->fwblks = SPECTRA_START_BLOCK;
        }
}

static uint16_t denali_nand_timing_set(struct denali_nand_info *denali)
{
        uint16_t status = PASS;
        uint32_t id_bytes[8], addr;
        uint8_t maf_id, device_id;
        int i;

        dev_dbg(denali->dev, "%s, Line %d, Function: %s\n",
                        __FILE__, __LINE__, __func__);

        /*
         * Use read id method to get device ID and other params.
         * For some NAND chips, controller can't report the correct
         * device ID by reading from DEVICE_ID register
         */
        addr = MODE_11 | BANK(denali->flash_bank);
        index_addr(denali, addr | 0, 0x90);
        index_addr(denali, addr | 1, 0);
        for (i = 0; i < 8; i++)
                index_addr_read_data(denali, addr | 2, &id_bytes[i]);
        maf_id = id_bytes[0];
        device_id = id_bytes[1];

        if (ioread32(denali->flash_reg + ONFI_DEVICE_NO_OF_LUNS) &
                ONFI_DEVICE_NO_OF_LUNS__ONFI_DEVICE) { /* ONFI 1.0 NAND */
                if (FAIL == get_onfi_nand_para(denali))
                        return FAIL;
        } else if (maf_id == 0xEC) { /* Samsung NAND */
                get_samsung_nand_para(denali, device_id);
        } else if (maf_id == 0x98) { /* Toshiba NAND */
                get_toshiba_nand_para(denali);
        } else if (maf_id == 0xAD) { /* Hynix NAND */
                get_hynix_nand_para(denali, device_id);
        }

        dev_info(denali->dev,
                        "Dump timing register values:\n"
                        "acc_clks: %d, re_2_we: %d, re_2_re: %d\n"
                        "we_2_re: %d, addr_2_data: %d, rdwr_en_lo_cnt: %d\n"
                        "rdwr_en_hi_cnt: %d, cs_setup_cnt: %d\n",
                        ioread32(denali->flash_reg + ACC_CLKS),
                        ioread32(denali->flash_reg + RE_2_WE),
                        ioread32(denali->flash_reg + RE_2_RE),
                        ioread32(denali->flash_reg + WE_2_RE),
                        ioread32(denali->flash_reg + ADDR_2_DATA),
                        ioread32(denali->flash_reg + RDWR_EN_LO_CNT),
                        ioread32(denali->flash_reg + RDWR_EN_HI_CNT),
                        ioread32(denali->flash_reg + CS_SETUP_CNT));

        find_valid_banks(denali);

        detect_partition_feature(denali);

        /*
         * If the user specified to override the default timings
         * with a specific ONFI mode, we apply those changes here.
         */
        if (onfi_timing_mode != NAND_DEFAULT_TIMINGS)
                nand_onfi_timing_set(denali, onfi_timing_mode);

        return status;
}

static void denali_set_intr_modes(struct denali_nand_info *denali,
                                        uint16_t INT_ENABLE)
{
        dev_dbg(denali->dev, "%s, Line %d, Function: %s\n",
                __FILE__, __LINE__, __func__);

        if (INT_ENABLE)
                iowrite32(1, denali->flash_reg + GLOBAL_INT_ENABLE);
        else
                iowrite32(0, denali->flash_reg + GLOBAL_INT_ENABLE);
}

/*
 * validation function to verify that the controlling software is making
 * a valid request
 */
static inline bool is_flash_bank_valid(int flash_bank)
{
        return flash_bank >= 0 && flash_bank < 4;
}

static void denali_irq_init(struct denali_nand_info *denali)
{
        uint32_t int_mask;
        int i;

        /* Disable global interrupts */
        denali_set_intr_modes(denali, false);

        int_mask = DENALI_IRQ_ALL;

        /* Clear all status bits */
        for (i = 0; i < denali->max_banks; ++i)
                iowrite32(0xFFFF, denali->flash_reg + INTR_STATUS(i));

        denali_irq_enable(denali, int_mask);
}

static void denali_irq_cleanup(int irqnum, struct denali_nand_info *denali)
{
        denali_set_intr_modes(denali, false);
        free_irq(irqnum, denali);
}

static void denali_irq_enable(struct denali_nand_info *denali,
                                                        uint32_t int_mask)
{
        int i;

        for (i = 0; i < denali->max_banks; ++i)
                iowrite32(int_mask, denali->flash_reg + INTR_EN(i));
}

/*
 * This function only returns when an interrupt that this driver cares about
 * occurs. This is to reduce the overhead of servicing interrupts
 */
static inline uint32_t denali_irq_detected(struct denali_nand_info *denali)
{
        return read_interrupt_status(denali) & DENALI_IRQ_ALL;
}

/* Interrupts are cleared by writing a 1 to the appropriate status bit */
static inline void clear_interrupt(struct denali_nand_info *denali,
                                                        uint32_t irq_mask)
{
        uint32_t intr_status_reg;

        intr_status_reg = INTR_STATUS(denali->flash_bank);

        iowrite32(irq_mask, denali->flash_reg + intr_status_reg);
}

static void clear_interrupts(struct denali_nand_info *denali)
{
        uint32_t status;

        spin_lock_irq(&denali->irq_lock);

        status = read_interrupt_status(denali);
        clear_interrupt(denali, status);

        denali->irq_status = 0x0;
        spin_unlock_irq(&denali->irq_lock);
}

static uint32_t read_interrupt_status(struct denali_nand_info *denali)
{
        uint32_t intr_status_reg;

        intr_status_reg = INTR_STATUS(denali->flash_bank);

        return ioread32(denali->flash_reg + intr_status_reg);
}

/*
 * This is the interrupt service routine. It handles all interrupts
 * sent to this device. Note that on CE4100, this is a shared interrupt.
 */
static irqreturn_t denali_isr(int irq, void *dev_id)
{
        struct denali_nand_info *denali = dev_id;
        uint32_t irq_status;
        irqreturn_t result = IRQ_NONE;

        spin_lock(&denali->irq_lock);

        /* check to see if a valid NAND chip has been selected. */
        if (is_flash_bank_valid(denali->flash_bank)) {
                /*
                 * check to see if controller generated the interrupt,
                 * since this is a shared interrupt
                 */
                irq_status = denali_irq_detected(denali);
                if (irq_status != 0) {
                        /* handle interrupt */
                        /* first acknowledge it */
                        clear_interrupt(denali, irq_status);
                        /*
                         * store the status in the device context for someone
                         * to read
                         */
                        denali->irq_status |= irq_status;
                        /* notify anyone who cares that it happened */
                        complete(&denali->complete);
                        /* tell the OS that we've handled this */
                        result = IRQ_HANDLED;
                }
        }
        spin_unlock(&denali->irq_lock);
        return result;
}
#define BANK(x) ((x) << 24)

static uint32_t wait_for_irq(struct denali_nand_info *denali, uint32_t irq_mask)
{
        unsigned long comp_res;
        uint32_t intr_status;
        unsigned long timeout = msecs_to_jiffies(1000);

        do {
                comp_res =
                        wait_for_completion_timeout(&denali->complete, timeout);
                spin_lock_irq(&denali->irq_lock);
                intr_status = denali->irq_status;

                if (intr_status & irq_mask) {
                        denali->irq_status &= ~irq_mask;
                        spin_unlock_irq(&denali->irq_lock);
                        /* our interrupt was detected */
                        break;
                }

                /*
                 * these are not the interrupts you are looking for -
                 * need to wait again
                 */
                spin_unlock_irq(&denali->irq_lock);
        } while (comp_res != 0);

        if (comp_res == 0) {
                /* timeout */
                pr_err("timeout occurred, status = 0x%x, mask = 0x%x\n",
                                intr_status, irq_mask);

                intr_status = 0;
        }
        return intr_status;
}

/*
 * This helper function setups the registers for ECC and whether or not
 * the spare area will be transferred.
 */
static void setup_ecc_for_xfer(struct denali_nand_info *denali, bool ecc_en,
                                bool transfer_spare)
{
        int ecc_en_flag, transfer_spare_flag;

        /* set ECC, transfer spare bits if needed */
        ecc_en_flag = ecc_en ? ECC_ENABLE__FLAG : 0;
        transfer_spare_flag = transfer_spare ? TRANSFER_SPARE_REG__FLAG : 0;

        /* Enable spare area/ECC per user's request. */
        iowrite32(ecc_en_flag, denali->flash_reg + ECC_ENABLE);
        iowrite32(transfer_spare_flag, denali->flash_reg + TRANSFER_SPARE_REG);
}

/*
 * sends a pipeline command operation to the controller. See the Denali NAND
 * controller's user guide for more information (section 4.2.3.6).
 */
static int denali_send_pipeline_cmd(struct denali_nand_info *denali,
                                    bool ecc_en, bool transfer_spare,
                                    int access_type, int op)
{
        int status = PASS;
        uint32_t page_count = 1;
        uint32_t addr, cmd, irq_status, irq_mask;

        if (op == DENALI_READ)
                irq_mask = INTR_STATUS__LOAD_COMP;
        else if (op == DENALI_WRITE)
                irq_mask = 0;
        else
                BUG();

        setup_ecc_for_xfer(denali, ecc_en, transfer_spare);

        clear_interrupts(denali);

        addr = BANK(denali->flash_bank) | denali->page;

        if (op == DENALI_WRITE && access_type != SPARE_ACCESS) {
                cmd = MODE_01 | addr;
                iowrite32(cmd, denali->flash_mem);
        } else if (op == DENALI_WRITE && access_type == SPARE_ACCESS) {
                /* read spare area */
                cmd = MODE_10 | addr;
                index_addr(denali, cmd, access_type);

                cmd = MODE_01 | addr;
                iowrite32(cmd, denali->flash_mem);
        } else if (op == DENALI_READ) {
                /* setup page read request for access type */
                cmd = MODE_10 | addr;
                index_addr(denali, cmd, access_type);

                /*
                 * page 33 of the NAND controller spec indicates we should not
                 * use the pipeline commands in Spare area only mode.
                 * So we don't.
                 */
                if (access_type == SPARE_ACCESS) {
                        cmd = MODE_01 | addr;
                        iowrite32(cmd, denali->flash_mem);
                } else {
                        index_addr(denali, cmd,
                                        PIPELINE_ACCESS | op | page_count);

                        /*
                         * wait for command to be accepted
                         * can always use status0 bit as the
                         * mask is identical for each bank.
                         */
                        irq_status = wait_for_irq(denali, irq_mask);

                        if (irq_status == 0) {
                                dev_err(denali->dev,
                                        "cmd, page, addr on timeout (0x%x, 0x%x, 0x%x)\n",
                                        cmd, denali->page, addr);
                                status = FAIL;
                        } else {
                                cmd = MODE_01 | addr;
                                iowrite32(cmd, denali->flash_mem);
                        }
                }
        }
        return status;
}

/* helper function that simply writes a buffer to the flash */
static int write_data_to_flash_mem(struct denali_nand_info *denali,
                                   const uint8_t *buf, int len)
{
        uint32_t *buf32;
        int i;

        /*
         * verify that the len is a multiple of 4.
         * see comment in read_data_from_flash_mem()
         */
        BUG_ON((len % 4) != 0);

        /* write the data to the flash memory */
        buf32 = (uint32_t *)buf;
        for (i = 0; i < len / 4; i++)
                iowrite32(*buf32++, denali->flash_mem + 0x10);
        return i * 4; /* intent is to return the number of bytes read */
}

/* helper function that simply reads a buffer from the flash */
static int read_data_from_flash_mem(struct denali_nand_info *denali,
                                    uint8_t *buf, int len)
{
        uint32_t *buf32;
        int i;

        /*
         * we assume that len will be a multiple of 4, if not it would be nice
         * to know about it ASAP rather than have random failures...
         * This assumption is based on the fact that this function is designed
         * to be used to read flash pages, which are typically multiples of 4.
         */
        BUG_ON((len % 4) != 0);

        /* transfer the data from the flash */
        buf32 = (uint32_t *)buf;
        for (i = 0; i < len / 4; i++)
                *buf32++ = ioread32(denali->flash_mem + 0x10);
        return i * 4; /* intent is to return the number of bytes read */
}

/* writes OOB data to the device */
static int write_oob_data(struct mtd_info *mtd, uint8_t *buf, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint32_t irq_status;
        uint32_t irq_mask = INTR_STATUS__PROGRAM_COMP |
                                                INTR_STATUS__PROGRAM_FAIL;
        int status = 0;

        denali->page = page;

        if (denali_send_pipeline_cmd(denali, false, false, SPARE_ACCESS,
                                                        DENALI_WRITE) == PASS) {
                write_data_to_flash_mem(denali, buf, mtd->oobsize);

                /* wait for operation to complete */
                irq_status = wait_for_irq(denali, irq_mask);

                if (irq_status == 0) {
                        dev_err(denali->dev, "OOB write failed\n");
                        status = -EIO;
                }
        } else {
                dev_err(denali->dev, "unable to send pipeline command\n");
                status = -EIO;
        }
        return status;
}

/* reads OOB data from the device */
static void read_oob_data(struct mtd_info *mtd, uint8_t *buf, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint32_t irq_mask = INTR_STATUS__LOAD_COMP;
        uint32_t irq_status, addr, cmd;

        denali->page = page;

        if (denali_send_pipeline_cmd(denali, false, true, SPARE_ACCESS,
                                                        DENALI_READ) == PASS) {
                read_data_from_flash_mem(denali, buf, mtd->oobsize);

                /*
                 * wait for command to be accepted
                 * can always use status0 bit as the
                 * mask is identical for each bank.
                 */
                irq_status = wait_for_irq(denali, irq_mask);

                if (irq_status == 0)
                        dev_err(denali->dev, "page on OOB timeout %d\n",
                                        denali->page);

                /*
                 * We set the device back to MAIN_ACCESS here as I observed
                 * instability with the controller if you do a block erase
                 * and the last transaction was a SPARE_ACCESS. Block erase
                 * is reliable (according to the MTD test infrastructure)
                 * if you are in MAIN_ACCESS.
                 */
                addr = BANK(denali->flash_bank) | denali->page;
                cmd = MODE_10 | addr;
                index_addr(denali, cmd, MAIN_ACCESS);
        }
}

/*
 * this function examines buffers to see if they contain data that
 * indicate that the buffer is part of an erased region of flash.
 */
static bool is_erased(uint8_t *buf, int len)
{
        int i;

        for (i = 0; i < len; i++)
                if (buf[i] != 0xFF)
                        return false;
        return true;
}
#define ECC_SECTOR_SIZE 512

#define ECC_SECTOR(x)   (((x) & ECC_ERROR_ADDRESS__SECTOR_NR) >> 12)
#define ECC_BYTE(x)     (((x) & ECC_ERROR_ADDRESS__OFFSET))
#define ECC_CORRECTION_VALUE(x) ((x) & ERR_CORRECTION_INFO__BYTEMASK)
#define ECC_ERROR_CORRECTABLE(x) (!((x) & ERR_CORRECTION_INFO__ERROR_TYPE))
#define ECC_ERR_DEVICE(x)       (((x) & ERR_CORRECTION_INFO__DEVICE_NR) >> 8)
#define ECC_LAST_ERR(x)         ((x) & ERR_CORRECTION_INFO__LAST_ERR_INFO)

static bool handle_ecc(struct denali_nand_info *denali, uint8_t *buf,
                       uint32_t irq_status, unsigned int *max_bitflips)
{
        bool check_erased_page = false;
        unsigned int bitflips = 0;

        if (irq_status & INTR_STATUS__ECC_ERR) {
                /* read the ECC errors. we'll ignore them for now */
                uint32_t err_address, err_correction_info, err_byte,
                         err_sector, err_device, err_correction_value;
                denali_set_intr_modes(denali, false);

                do {
                        err_address = ioread32(denali->flash_reg +
                                                ECC_ERROR_ADDRESS);
                        err_sector = ECC_SECTOR(err_address);
                        err_byte = ECC_BYTE(err_address);

                        err_correction_info = ioread32(denali->flash_reg +
                                                ERR_CORRECTION_INFO);
                        err_correction_value =
                                ECC_CORRECTION_VALUE(err_correction_info);
                        err_device = ECC_ERR_DEVICE(err_correction_info);

                        if (ECC_ERROR_CORRECTABLE(err_correction_info)) {
                                /*
                                 * If err_byte is larger than ECC_SECTOR_SIZE,
                                 * means error happened in OOB, so we ignore
                                 * it. It's no need for us to correct it
                                 * err_device is represented the NAND error
                                 * bits are happened in if there are more
                                 * than one NAND connected.
                                 */
                                if (err_byte < ECC_SECTOR_SIZE) {
                                        int offset;

                                        offset = (err_sector *
                                                        ECC_SECTOR_SIZE +
                                                        err_byte) *
                                                        denali->devnum +
                                                        err_device;
                                        /* correct the ECC error */
                                        buf[offset] ^= err_correction_value;
                                        denali->mtd.ecc_stats.corrected++;
                                        bitflips++;
                                }
                        } else {
                                /*
                                 * if the error is not correctable, need to
                                 * look at the page to see if it is an erased
                                 * page. if so, then it's not a real ECC error
                                 */
                                check_erased_page = true;
                        }
                } while (!ECC_LAST_ERR(err_correction_info));

                /*
                 * Once handle all ecc errors, controller will triger
                 * a ECC_TRANSACTION_DONE interrupt, so here just wait
                 * for a while for this interrupt
                 */
                while (!(read_interrupt_status(denali) &
                                INTR_STATUS__ECC_TRANSACTION_DONE))
                        cpu_relax();
                clear_interrupts(denali);
                denali_set_intr_modes(denali, true);
        }
        *max_bitflips = bitflips;
        return check_erased_page;
}

/* programs the controller to either enable/disable DMA transfers */
static void denali_enable_dma(struct denali_nand_info *denali, bool en)
{
        iowrite32(en ? DMA_ENABLE__FLAG : 0, denali->flash_reg + DMA_ENABLE);
        ioread32(denali->flash_reg + DMA_ENABLE);
}

/* setups the HW to perform the data DMA */
static void denali_setup_dma(struct denali_nand_info *denali, int op)
{
        uint32_t mode;
        const int page_count = 1;
        uint32_t addr = denali->buf.dma_buf;

        mode = MODE_10 | BANK(denali->flash_bank);

        /* DMA is a four step process */

        /* 1. setup transfer type and # of pages */
        index_addr(denali, mode | denali->page, 0x2000 | op | page_count);

        /* 2. set memory high address bits 23:8 */
        index_addr(denali, mode | ((addr >> 16) << 8), 0x2200);

        /* 3. set memory low address bits 23:8 */
        index_addr(denali, mode | ((addr & 0xffff) << 8), 0x2300);

        /* 4. interrupt when complete, burst len = 64 bytes */
        index_addr(denali, mode | 0x14000, 0x2400);
}

/*
 * writes a page. user specifies type, and this function handles the
 * configuration details.
 */
static int write_page(struct mtd_info *mtd, struct nand_chip *chip,
                        const uint8_t *buf, bool raw_xfer)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        dma_addr_t addr = denali->buf.dma_buf;
        size_t size = denali->mtd.writesize + denali->mtd.oobsize;
        uint32_t irq_status;
        uint32_t irq_mask = INTR_STATUS__DMA_CMD_COMP |
                                                INTR_STATUS__PROGRAM_FAIL;

        /*
         * if it is a raw xfer, we want to disable ecc and send the spare area.
         * !raw_xfer - enable ecc
         * raw_xfer - transfer spare
         */
        setup_ecc_for_xfer(denali, !raw_xfer, raw_xfer);

        /* copy buffer into DMA buffer */
        memcpy(denali->buf.buf, buf, mtd->writesize);

        if (raw_xfer) {
                /* transfer the data to the spare area */
                memcpy(denali->buf.buf + mtd->writesize,
                        chip->oob_poi,
                        mtd->oobsize);
        }

        dma_sync_single_for_device(denali->dev, addr, size, DMA_TO_DEVICE);

        clear_interrupts(denali);
        denali_enable_dma(denali, true);

        denali_setup_dma(denali, DENALI_WRITE);

        /* wait for operation to complete */
        irq_status = wait_for_irq(denali, irq_mask);

        if (irq_status == 0) {
                dev_err(denali->dev, "timeout on write_page (type = %d)\n",
                        raw_xfer);
                denali->status = NAND_STATUS_FAIL;
        }

        denali_enable_dma(denali, false);
        dma_sync_single_for_cpu(denali->dev, addr, size, DMA_TO_DEVICE);

        return 0;
}

/* NAND core entry points */

/*
 * this is the callback that the NAND core calls to write a page. Since
 * writing a page with ECC or without is similar, all the work is done
 * by write_page above.
 */
static int denali_write_page(struct mtd_info *mtd, struct nand_chip *chip,
                                const uint8_t *buf, int oob_required)
{
        /*
         * for regular page writes, we let HW handle all the ECC
         * data written to the device.
         */
        return write_page(mtd, chip, buf, false);
}

/*
 * This is the callback that the NAND core calls to write a page without ECC.
 * raw access is similar to ECC page writes, so all the work is done in the
 * write_page() function above.
 */
static int denali_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                                        const uint8_t *buf, int oob_required)
{
        /*
         * for raw page writes, we want to disable ECC and simply write
         * whatever data is in the buffer.
         */
        return write_page(mtd, chip, buf, true);
}

static int denali_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
                            int page)
{
        return write_oob_data(mtd, chip->oob_poi, page);
}

static int denali_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
                           int page)
{
        read_oob_data(mtd, chip->oob_poi, page);

        return 0;
}

static int denali_read_page(struct mtd_info *mtd, struct nand_chip *chip,
                            uint8_t *buf, int oob_required, int page)
{
        unsigned int max_bitflips;
        struct denali_nand_info *denali = mtd_to_denali(mtd);

        dma_addr_t addr = denali->buf.dma_buf;
        size_t size = denali->mtd.writesize + denali->mtd.oobsize;

        uint32_t irq_status;
        uint32_t irq_mask = INTR_STATUS__ECC_TRANSACTION_DONE |
                            INTR_STATUS__ECC_ERR;
        bool check_erased_page = false;

        if (page != denali->page) {
                dev_err(denali->dev,
                        "IN %s: page %d is not equal to denali->page %d",
                        __func__, page, denali->page);
                BUG();
        }

        setup_ecc_for_xfer(denali, true, false);

        denali_enable_dma(denali, true);
        dma_sync_single_for_device(denali->dev, addr, size, DMA_FROM_DEVICE);

        clear_interrupts(denali);
        denali_setup_dma(denali, DENALI_READ);

        /* wait for operation to complete */
        irq_status = wait_for_irq(denali, irq_mask);

        dma_sync_single_for_cpu(denali->dev, addr, size, DMA_FROM_DEVICE);

        memcpy(buf, denali->buf.buf, mtd->writesize);

        check_erased_page = handle_ecc(denali, buf, irq_status, &max_bitflips);
        denali_enable_dma(denali, false);

        if (check_erased_page) {
                read_oob_data(&denali->mtd, chip->oob_poi, denali->page);

                /* check ECC failures that may have occurred on erased pages */
                if (check_erased_page) {
                        if (!is_erased(buf, denali->mtd.writesize))
                                denali->mtd.ecc_stats.failed++;
                        if (!is_erased(buf, denali->mtd.oobsize))
                                denali->mtd.ecc_stats.failed++;
                }
        }
        return max_bitflips;
}

static int denali_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                                uint8_t *buf, int oob_required, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        dma_addr_t addr = denali->buf.dma_buf;
        size_t size = denali->mtd.writesize + denali->mtd.oobsize;
        uint32_t irq_mask = INTR_STATUS__DMA_CMD_COMP;

        if (page != denali->page) {
                dev_err(denali->dev,
                        "IN %s: page %d is not equal to denali->page %d",
                        __func__, page, denali->page);
                BUG();
        }

        setup_ecc_for_xfer(denali, false, true);
        denali_enable_dma(denali, true);

        dma_sync_single_for_device(denali->dev, addr, size, DMA_FROM_DEVICE);

        clear_interrupts(denali);
        denali_setup_dma(denali, DENALI_READ);

        /* wait for operation to complete */
        wait_for_irq(denali, irq_mask);

        dma_sync_single_for_cpu(denali->dev, addr, size, DMA_FROM_DEVICE);

        denali_enable_dma(denali, false);

        memcpy(buf, denali->buf.buf, mtd->writesize);
        memcpy(chip->oob_poi, denali->buf.buf + mtd->writesize, mtd->oobsize);

        return 0;
}

static uint8_t denali_read_byte(struct mtd_info *mtd)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint8_t result = 0xff;

        if (denali->buf.head < denali->buf.tail)
                result = denali->buf.buf[denali->buf.head++];

        return result;
}

static void denali_select_chip(struct mtd_info *mtd, int chip)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);

        spin_lock_irq(&denali->irq_lock);
        denali->flash_bank = chip;
        spin_unlock_irq(&denali->irq_lock);
}

static int denali_waitfunc(struct mtd_info *mtd, struct nand_chip *chip)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        int status = denali->status;

        denali->status = 0;

        return status;
}

static int denali_erase(struct mtd_info *mtd, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);

        uint32_t cmd, irq_status;

        clear_interrupts(denali);

        /* setup page read request for access type */
        cmd = MODE_10 | BANK(denali->flash_bank) | page;
        index_addr(denali, cmd, 0x1);

        /* wait for erase to complete or failure to occur */
        irq_status = wait_for_irq(denali, INTR_STATUS__ERASE_COMP |
                                        INTR_STATUS__ERASE_FAIL);

        return irq_status & INTR_STATUS__ERASE_FAIL ? NAND_STATUS_FAIL : PASS;
}

static void denali_cmdfunc(struct mtd_info *mtd, unsigned int cmd, int col,
                           int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint32_t addr, id;
        int i;

        switch (cmd) {
        case NAND_CMD_PAGEPROG:
                break;
        case NAND_CMD_STATUS:
                read_status(denali);
                break;
        case NAND_CMD_READID:
        case NAND_CMD_PARAM:
                reset_buf(denali);
                /*
                 * sometimes ManufactureId read from register is not right
                 * e.g. some of Micron MT29F32G08QAA MLC NAND chips
                 * So here we send READID cmd to NAND insteand
                 */
                addr = MODE_11 | BANK(denali->flash_bank);
                index_addr(denali, addr | 0, 0x90);
                index_addr(denali, addr | 1, 0);
                for (i = 0; i < 8; i++) {
                        index_addr_read_data(denali, addr | 2, &id);
                        write_byte_to_buf(denali, id);
                }
                break;
        case NAND_CMD_READ0:
        case NAND_CMD_SEQIN:
                denali->page = page;
                break;
        case NAND_CMD_RESET:
                reset_bank(denali);
                break;
        case NAND_CMD_READOOB:
                /* TODO: Read OOB data */
                break;
        default:
                pr_err(": unsupported command received 0x%x\n", cmd);
                break;
        }
}
/* end NAND core entry points */

/* Initialization code to bring the device up to a known good state */
static void denali_hw_init(struct denali_nand_info *denali)
{
        /*
         * tell driver how many bit controller will skip before
         * writing ECC code in OOB, this register may be already
         * set by firmware. So we read this value out.
         * if this value is 0, just let it be.
         */
        denali->bbtskipbytes = ioread32(denali->flash_reg +
                                                SPARE_AREA_SKIP_BYTES);
        detect_max_banks(denali);
        denali_nand_reset(denali);
        iowrite32(0x0F, denali->flash_reg + RB_PIN_ENABLED);
        iowrite32(CHIP_EN_DONT_CARE__FLAG,
                        denali->flash_reg + CHIP_ENABLE_DONT_CARE);

        iowrite32(0xffff, denali->flash_reg + SPARE_AREA_MARKER);

        /* Should set value for these registers when init */
        iowrite32(0, denali->flash_reg + TWO_ROW_ADDR_CYCLES);
        iowrite32(1, denali->flash_reg + ECC_ENABLE);
        denali_nand_timing_set(denali);
        denali_irq_init(denali);
}

/*
 * Althogh controller spec said SLC ECC is forceb to be 4bit,
 * but denali controller in MRST only support 15bit and 8bit ECC
 * correction
 */
#define ECC_8BITS       14
static struct nand_ecclayout nand_8bit_oob = {
        .eccbytes = 14,
};

#define ECC_15BITS      26
static struct nand_ecclayout nand_15bit_oob = {
        .eccbytes = 26,
};

static uint8_t bbt_pattern[] = {'B', 'b', 't', '0' };
static uint8_t mirror_pattern[] = {'1', 't', 'b', 'B' };

static struct nand_bbt_descr bbt_main_descr = {
        .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
                | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
        .offs = 8,
        .len = 4,
        .veroffs = 12,
        .maxblocks = 4,
        .pattern = bbt_pattern,
};

static struct nand_bbt_descr bbt_mirror_descr = {
        .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
                | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
        .offs = 8,
        .len = 4,
        .veroffs = 12,
        .maxblocks = 4,
        .pattern = mirror_pattern,
};

/* initialize driver data structures */
static void denali_drv_init(struct denali_nand_info *denali)
{
        denali->idx = 0;

        /* setup interrupt handler */
        /*
         * the completion object will be used to notify
         * the callee that the interrupt is done
         */
        init_completion(&denali->complete);

        /*
         * the spinlock will be used to synchronize the ISR with any
         * element that might be access shared data (interrupt status)
         */
        spin_lock_init(&denali->irq_lock);

        /* indicate that MTD has not selected a valid bank yet */
        denali->flash_bank = CHIP_SELECT_INVALID;

        /* initialize our irq_status variable to indicate no interrupts */
        denali->irq_status = 0;
}

int denali_init(struct denali_nand_info *denali)
{
        int ret;

        if (denali->platform == INTEL_CE4100) {
                /*
                 * Due to a silicon limitation, we can only support
                 * ONFI timing mode 1 and below.
                 */
                if (onfi_timing_mode < -1 || onfi_timing_mode > 1) {
                        pr_err("Intel CE4100 only supports ONFI timing mode 1 or below\n");
                        return -EINVAL;
                }
        }

        /* allocate a temporary buffer for nand_scan_ident() */
        denali->buf.buf = devm_kzalloc(denali->dev, PAGE_SIZE,
                                        GFP_DMA | GFP_KERNEL);
        if (!denali->buf.buf)
                return -ENOMEM;

        denali->mtd.dev.parent = denali->dev;
        denali_hw_init(denali);
        denali_drv_init(denali);

        /*
         * denali_isr register is done after all the hardware
         * initilization is finished
         */
        if (request_irq(denali->irq, denali_isr, IRQF_SHARED,
                        DENALI_NAND_NAME, denali)) {
                pr_err("Spectra: Unable to allocate IRQ\n");
                return -ENODEV;
        }

        /* now that our ISR is registered, we can enable interrupts */
        denali_set_intr_modes(denali, true);
        denali->mtd.name = "denali-nand";
        denali->mtd.owner = THIS_MODULE;
        denali->mtd.priv = &denali->nand;

        /* register the driver with the NAND core subsystem */
        denali->nand.select_chip = denali_select_chip;
        denali->nand.cmdfunc = denali_cmdfunc;
        denali->nand.read_byte = denali_read_byte;
        denali->nand.waitfunc = denali_waitfunc;

        /*
         * scan for NAND devices attached to the controller
         * this is the first stage in a two step process to register
         * with the nand subsystem
         */
        if (nand_scan_ident(&denali->mtd, denali->max_banks, NULL)) {
                ret = -ENXIO;
                goto failed_req_irq;
        }

        /* allocate the right size buffer now */
        devm_kfree(denali->dev, denali->buf.buf);
        denali->buf.buf = devm_kzalloc(denali->dev,
                             denali->mtd.writesize + denali->mtd.oobsize,
                             GFP_KERNEL);
        if (!denali->buf.buf) {
                ret = -ENOMEM;
                goto failed_req_irq;
        }

        /* Is 32-bit DMA supported? */
        ret = dma_set_mask(denali->dev, DMA_BIT_MASK(32));
        if (ret) {
                pr_err("Spectra: no usable DMA configuration\n");
                goto failed_req_irq;
        }

        denali->buf.dma_buf = dma_map_single(denali->dev, denali->buf.buf,
                             denali->mtd.writesize + denali->mtd.oobsize,
                             DMA_BIDIRECTIONAL);
        if (dma_mapping_error(denali->dev, denali->buf.dma_buf)) {
                dev_err(denali->dev, "Spectra: failed to map DMA buffer\n");
                ret = -EIO;
                goto failed_req_irq;
        }

        /*
         * support for multi nand
         * MTD known nothing about multi nand, so we should tell it
         * the real pagesize and anything necessery
         */
        denali->devnum = ioread32(denali->flash_reg + DEVICES_CONNECTED);
        denali->nand.chipsize <<= (denali->devnum - 1);
        denali->nand.page_shift += (denali->devnum - 1);
        denali->nand.pagemask = (denali->nand.chipsize >>
                                                denali->nand.page_shift) - 1;
        denali->nand.bbt_erase_shift += (denali->devnum - 1);
        denali->nand.phys_erase_shift = denali->nand.bbt_erase_shift;
        denali->nand.chip_shift += (denali->devnum - 1);
        denali->mtd.writesize <<= (denali->devnum - 1);
        denali->mtd.oobsize <<= (denali->devnum - 1);
        denali->mtd.erasesize <<= (denali->devnum - 1);
        denali->mtd.size = denali->nand.numchips * denali->nand.chipsize;
        denali->bbtskipbytes *= denali->devnum;

        /*
         * second stage of the NAND scan
         * this stage requires information regarding ECC and
         * bad block management.
         */

        /* Bad block management */
        denali->nand.bbt_td = &bbt_main_descr;
        denali->nand.bbt_md = &bbt_mirror_descr;

        /* skip the scan for now until we have OOB read and write support */
        denali->nand.bbt_options |= NAND_BBT_USE_FLASH;
        denali->nand.options |= NAND_SKIP_BBTSCAN;
        denali->nand.ecc.mode = NAND_ECC_HW_SYNDROME;

        /* no subpage writes on denali */
        denali->nand.options |= NAND_NO_SUBPAGE_WRITE;

        /*
         * Denali Controller only support 15bit and 8bit ECC in MRST,
         * so just let controller do 15bit ECC for MLC and 8bit ECC for
         * SLC if possible.
         * */
        if (!nand_is_slc(&denali->nand) &&
                        (denali->mtd.oobsize > (denali->bbtskipbytes +
                        ECC_15BITS * (denali->mtd.writesize /
                        ECC_SECTOR_SIZE)))) {
                /* if MLC OOB size is large enough, use 15bit ECC*/
                denali->nand.ecc.strength = 15;
                denali->nand.ecc.layout = &nand_15bit_oob;
                denali->nand.ecc.bytes = ECC_15BITS;
                iowrite32(15, denali->flash_reg + ECC_CORRECTION);
        } else if (denali->mtd.oobsize < (denali->bbtskipbytes +
                        ECC_8BITS * (denali->mtd.writesize /
                        ECC_SECTOR_SIZE))) {
                pr_err("Your NAND chip OOB is not large enough to contain 8bit ECC correction codes");
                goto failed_req_irq;
        } else {
                denali->nand.ecc.strength = 8;
                denali->nand.ecc.layout = &nand_8bit_oob;
                denali->nand.ecc.bytes = ECC_8BITS;
                iowrite32(8, denali->flash_reg + ECC_CORRECTION);
        }

        denali->nand.ecc.bytes *= denali->devnum;
        denali->nand.ecc.strength *= denali->devnum;
        denali->nand.ecc.layout->eccbytes *=
                denali->mtd.writesize / ECC_SECTOR_SIZE;
        denali->nand.ecc.layout->oobfree[0].offset =
                denali->bbtskipbytes + denali->nand.ecc.layout->eccbytes;
        denali->nand.ecc.layout->oobfree[0].length =
                denali->mtd.oobsize - denali->nand.ecc.layout->eccbytes -
                denali->bbtskipbytes;

        /*
         * Let driver know the total blocks number and how many blocks
         * contained by each nand chip. blksperchip will help driver to
         * know how many blocks is taken by FW.
         */
        denali->totalblks = denali->mtd.size >> denali->nand.phys_erase_shift;
        denali->blksperchip = denali->totalblks / denali->nand.numchips;

        /* override the default read operations */
        denali->nand.ecc.size = ECC_SECTOR_SIZE * denali->devnum;
        denali->nand.ecc.read_page = denali_read_page;
        denali->nand.ecc.read_page_raw = denali_read_page_raw;
        denali->nand.ecc.write_page = denali_write_page;
        denali->nand.ecc.write_page_raw = denali_write_page_raw;
        denali->nand.ecc.read_oob = denali_read_oob;
        denali->nand.ecc.write_oob = denali_write_oob;
        denali->nand.erase = denali_erase;

        if (nand_scan_tail(&denali->mtd)) {
                ret = -ENXIO;
                goto failed_req_irq;
        }

        ret = mtd_device_register(&denali->mtd, NULL, 0);
        if (ret) {
                dev_err(denali->dev, "Spectra: Failed to register MTD: %d\n",
                                ret);
                goto failed_req_irq;
        }
        return 0;

failed_req_irq:
        denali_irq_cleanup(denali->irq, denali);

        return ret;
}
EXPORT_SYMBOL(denali_init);

/* driver exit point */
void denali_remove(struct denali_nand_info *denali)
{
        denali_irq_cleanup(denali->irq, denali);
        dma_unmap_single(denali->dev, denali->buf.dma_buf,
                         denali->mtd.writesize + denali->mtd.oobsize,
                         DMA_BIDIRECTIONAL);
}
EXPORT_SYMBOL(denali_remove);