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/*
 * Driver for the built-in NAND controller of the Atheros AR934x SoCs
 *
 * Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include <linux/version.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/dma-mapping.h>
#include <linux/mtd/mtd.h>
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,14,0)
#include <linux/mtd/nand.h>
#else
#include <linux/mtd/rawnand.h>
#endif
#include <linux/mtd/partitions.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/slab.h>

#include <linux/platform/ar934x_nfc.h>

#define AR934X_NFC_REG_CMD              0x00
#define AR934X_NFC_REG_CTRL             0x04
#define AR934X_NFC_REG_STATUS           0x08
#define AR934X_NFC_REG_INT_MASK         0x0c
#define AR934X_NFC_REG_INT_STATUS       0x10
#define AR934X_NFC_REG_ECC_CTRL         0x14
#define AR934X_NFC_REG_ECC_OFFSET       0x18
#define AR934X_NFC_REG_ADDR0_0          0x1c
#define AR934X_NFC_REG_ADDR0_1          0x24
#define AR934X_NFC_REG_ADDR1_0          0x20
#define AR934X_NFC_REG_ADDR1_1          0x28
#define AR934X_NFC_REG_SPARE_SIZE       0x30
#define AR934X_NFC_REG_PROTECT          0x38
#define AR934X_NFC_REG_LOOKUP_EN        0x40
#define AR934X_NFC_REG_LOOKUP(_x)       (0x44 + (_i) * 4)
#define AR934X_NFC_REG_DMA_ADDR         0x64
#define AR934X_NFC_REG_DMA_COUNT        0x68
#define AR934X_NFC_REG_DMA_CTRL         0x6c
#define AR934X_NFC_REG_MEM_CTRL         0x80
#define AR934X_NFC_REG_DATA_SIZE        0x84
#define AR934X_NFC_REG_READ_STATUS      0x88
#define AR934X_NFC_REG_TIME_SEQ         0x8c
#define AR934X_NFC_REG_TIMINGS_ASYN     0x90
#define AR934X_NFC_REG_TIMINGS_SYN      0x94
#define AR934X_NFC_REG_FIFO_DATA        0x98
#define AR934X_NFC_REG_TIME_MODE        0x9c
#define AR934X_NFC_REG_DMA_ADDR_OFFS    0xa0
#define AR934X_NFC_REG_FIFO_INIT        0xb0
#define AR934X_NFC_REG_GEN_SEQ_CTRL     0xb4

#define AR934X_NFC_CMD_CMD_SEQ_S                0
#define AR934X_NFC_CMD_CMD_SEQ_M                0x3f
#define   AR934X_NFC_CMD_SEQ_1C                 0x00
#define   AR934X_NFC_CMD_SEQ_ERASE              0x0e
#define   AR934X_NFC_CMD_SEQ_12                 0x0c
#define   AR934X_NFC_CMD_SEQ_1C1AXR             0x21
#define   AR934X_NFC_CMD_SEQ_S                  0x24
#define   AR934X_NFC_CMD_SEQ_1C3AXR             0x27
#define   AR934X_NFC_CMD_SEQ_1C5A1CXR           0x2a
#define   AR934X_NFC_CMD_SEQ_18                 0x32
#define AR934X_NFC_CMD_INPUT_SEL_SIU            0
#define AR934X_NFC_CMD_INPUT_SEL_DMA            BIT(6)
#define AR934X_NFC_CMD_ADDR_SEL_0               0
#define AR934X_NFC_CMD_ADDR_SEL_1               BIT(7)
#define AR934X_NFC_CMD_CMD0_S                   8
#define AR934X_NFC_CMD_CMD0_M                   0xff
#define AR934X_NFC_CMD_CMD1_S                   16
#define AR934X_NFC_CMD_CMD1_M                   0xff
#define AR934X_NFC_CMD_CMD2_S                   24
#define AR934X_NFC_CMD_CMD2_M                   0xff

#define AR934X_NFC_CTRL_ADDR_CYCLE0_M           0x7
#define AR934X_NFC_CTRL_ADDR_CYCLE0_S           0
#define AR934X_NFC_CTRL_SPARE_EN                BIT(3)
#define AR934X_NFC_CTRL_INT_EN                  BIT(4)
#define AR934X_NFC_CTRL_ECC_EN                  BIT(5)
#define AR934X_NFC_CTRL_BLOCK_SIZE_S            6
#define AR934X_NFC_CTRL_BLOCK_SIZE_M            0x3
#define   AR934X_NFC_CTRL_BLOCK_SIZE_32         0
#define   AR934X_NFC_CTRL_BLOCK_SIZE_64         1
#define   AR934X_NFC_CTRL_BLOCK_SIZE_128        2
#define   AR934X_NFC_CTRL_BLOCK_SIZE_256        3
#define AR934X_NFC_CTRL_PAGE_SIZE_S             8
#define AR934X_NFC_CTRL_PAGE_SIZE_M             0x7
#define   AR934X_NFC_CTRL_PAGE_SIZE_256         0
#define   AR934X_NFC_CTRL_PAGE_SIZE_512         1
#define   AR934X_NFC_CTRL_PAGE_SIZE_1024        2
#define   AR934X_NFC_CTRL_PAGE_SIZE_2048        3
#define   AR934X_NFC_CTRL_PAGE_SIZE_4096        4
#define   AR934X_NFC_CTRL_PAGE_SIZE_8192        5
#define   AR934X_NFC_CTRL_PAGE_SIZE_16384       6
#define AR934X_NFC_CTRL_CUSTOM_SIZE_EN          BIT(11)
#define AR934X_NFC_CTRL_IO_WIDTH_8BITS          0
#define AR934X_NFC_CTRL_IO_WIDTH_16BITS         BIT(12)
#define AR934X_NFC_CTRL_LOOKUP_EN               BIT(13)
#define AR934X_NFC_CTRL_PROT_EN                 BIT(14)
#define AR934X_NFC_CTRL_WORK_MODE_ASYNC         0
#define AR934X_NFC_CTRL_WORK_MODE_SYNC          BIT(15)
#define AR934X_NFC_CTRL_ADDR0_AUTO_INC          BIT(16)
#define AR934X_NFC_CTRL_ADDR1_AUTO_INC          BIT(17)
#define AR934X_NFC_CTRL_ADDR_CYCLE1_M           0x7
#define AR934X_NFC_CTRL_ADDR_CYCLE1_S           18
#define AR934X_NFC_CTRL_SMALL_PAGE              BIT(21)

#define AR934X_NFC_DMA_CTRL_DMA_START           BIT(7)
#define AR934X_NFC_DMA_CTRL_DMA_DIR_WRITE       0
#define AR934X_NFC_DMA_CTRL_DMA_DIR_READ        BIT(6)
#define AR934X_NFC_DMA_CTRL_DMA_MODE_SG         BIT(5)
#define AR934X_NFC_DMA_CTRL_DMA_BURST_S         2
#define AR934X_NFC_DMA_CTRL_DMA_BURST_0         0
#define AR934X_NFC_DMA_CTRL_DMA_BURST_1         1
#define AR934X_NFC_DMA_CTRL_DMA_BURST_2         2
#define AR934X_NFC_DMA_CTRL_DMA_BURST_3         3
#define AR934X_NFC_DMA_CTRL_DMA_BURST_4         4
#define AR934X_NFC_DMA_CTRL_DMA_BURST_5         5
#define AR934X_NFC_DMA_CTRL_ERR_FLAG            BIT(1)
#define AR934X_NFC_DMA_CTRL_DMA_READY           BIT(0)

#define AR934X_NFC_INT_DEV_RDY(_x)              BIT(4 + (_x))
#define AR934X_NFC_INT_CMD_END                  BIT(1)

#define AR934X_NFC_ECC_CTRL_ERR_THRES_S         8
#define AR934X_NFC_ECC_CTRL_ERR_THRES_M         0x1f
#define AR934X_NFC_ECC_CTRL_ECC_CAP_S           5
#define AR934X_NFC_ECC_CTRL_ECC_CAP_M           0x7
#define AR934X_NFC_ECC_CTRL_ECC_CAP_2           0
#define AR934X_NFC_ECC_CTRL_ECC_CAP_4           1
#define AR934X_NFC_ECC_CTRL_ECC_CAP_6           2
#define AR934X_NFC_ECC_CTRL_ECC_CAP_8           3
#define AR934X_NFC_ECC_CTRL_ECC_CAP_10          4
#define AR934X_NFC_ECC_CTRL_ECC_CAP_12          5
#define AR934X_NFC_ECC_CTRL_ECC_CAP_14          6
#define AR934X_NFC_ECC_CTRL_ECC_CAP_16          7
#define AR934X_NFC_ECC_CTRL_ERR_OVER            BIT(2)
#define AR934X_NFC_ECC_CTRL_ERR_UNCORRECT       BIT(1)
#define AR934X_NFC_ECC_CTRL_ERR_CORRECT         BIT(0)

#define AR934X_NFC_ECC_OFFS_OFSET_M             0xffff

/* default timing values */
#define AR934X_NFC_TIME_SEQ_DEFAULT     0x7fff
#define AR934X_NFC_TIMINGS_ASYN_DEFAULT 0x22
#define AR934X_NFC_TIMINGS_SYN_DEFAULT  0xf

#define AR934X_NFC_ID_BUF_SIZE          8
#define AR934X_NFC_DEV_READY_TIMEOUT    25 /* msecs */
#define AR934X_NFC_DMA_READY_TIMEOUT    25 /* msecs */
#define AR934X_NFC_DONE_TIMEOUT         1000
#define AR934X_NFC_DMA_RETRIES          20

#define AR934X_NFC_USE_IRQ              true
#define AR934X_NFC_IRQ_MASK             AR934X_NFC_INT_DEV_RDY(0)

#define  AR934X_NFC_GENSEQ_SMALL_PAGE_READ      0x30043

#undef AR934X_NFC_DEBUG_DATA
#undef AR934X_NFC_DEBUG

struct ar934x_nfc;

static inline  __attribute__ ((format (printf, 2, 3)))
void _nfc_dbg(struct ar934x_nfc *nfc, const char *fmt, ...)
{
}

#ifdef AR934X_NFC_DEBUG
#define nfc_dbg(_nfc, fmt, ...) \
        dev_info((_nfc)->parent, fmt, ##__VA_ARGS__)
#else
#define nfc_dbg(_nfc, fmt, ...) \
        _nfc_dbg((_nfc), fmt, ##__VA_ARGS__)
#endif /* AR934X_NFC_DEBUG */

#ifdef AR934X_NFC_DEBUG_DATA
static void
nfc_debug_data(const char *label, void *data, int len)
{
        print_hex_dump(KERN_WARNING, label, DUMP_PREFIX_OFFSET, 16, 1,
                       data, len, 0);
}
#else
static inline void
nfc_debug_data(const char *label, void *data, int len) {}
#endif /* AR934X_NFC_DEBUG_DATA */

struct ar934x_nfc {
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        struct mtd_info mtd;
#endif
        struct nand_chip nand_chip;
        struct device *parent;
        void __iomem *base;
        void (*select_chip)(int chip_no);
        bool swap_dma;
        int irq;
        wait_queue_head_t irq_waitq;

        bool spurious_irq_expected;
        u32 irq_status;

        u32 ctrl_reg;
        u32 ecc_ctrl_reg;
        u32 ecc_offset_reg;
        u32 ecc_thres;
        u32 ecc_oob_pos;

        bool small_page;
        unsigned int addr_count0;
        unsigned int addr_count1;

        u8 *buf;
        dma_addr_t buf_dma;
        unsigned int buf_size;
        int buf_index;

        bool read_id;

        int erase1_page_addr;

        int rndout_page_addr;
        int rndout_read_cmd;

        int seqin_page_addr;
        int seqin_column;
        int seqin_read_cmd;
};

static void ar934x_nfc_restart(struct ar934x_nfc *nfc);

static inline bool
is_all_ff(u8 *buf, int len)
{
        while (len--)
                if (buf[len] != 0xff)
                        return false;

        return true;
}

static inline void
ar934x_nfc_wr(struct ar934x_nfc *nfc, unsigned reg, u32 val)
{
        __raw_writel(val, nfc->base + reg);
}

static inline u32
ar934x_nfc_rr(struct ar934x_nfc *nfc, unsigned reg)
{
        return __raw_readl(nfc->base + reg);
}

static inline struct ar934x_nfc_platform_data *
ar934x_nfc_get_platform_data(struct ar934x_nfc *nfc)
{
        return nfc->parent->platform_data;
}

static inline struct
ar934x_nfc *mtd_to_ar934x_nfc(struct mtd_info *mtd)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        return container_of(mtd, struct ar934x_nfc, mtd);
#else
        struct nand_chip *chip = mtd_to_nand(mtd);

        return container_of(chip, struct ar934x_nfc, nand_chip);
#endif
}

static struct mtd_info *ar934x_nfc_to_mtd(struct ar934x_nfc *nfc)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        return &nfc->mtd;
#else
        return nand_to_mtd(&nfc->nand_chip);
#endif
}

static inline bool ar934x_nfc_use_irq(struct ar934x_nfc *nfc)
{
        return AR934X_NFC_USE_IRQ;
}

static inline void ar934x_nfc_write_cmd_reg(struct ar934x_nfc *nfc, u32 cmd_reg)
{
        wmb();

        ar934x_nfc_wr(nfc, AR934X_NFC_REG_CMD, cmd_reg);
        /* flush write */
        ar934x_nfc_rr(nfc, AR934X_NFC_REG_CMD);
}

static bool
__ar934x_nfc_dev_ready(struct ar934x_nfc *nfc)
{
        u32 status;

        status = ar934x_nfc_rr(nfc, AR934X_NFC_REG_STATUS);
        return (status & 0xff) == 0xff;
}

static inline bool
__ar934x_nfc_is_dma_ready(struct ar934x_nfc *nfc)
{
        u32 status;

        status = ar934x_nfc_rr(nfc, AR934X_NFC_REG_DMA_CTRL);
        return (status & AR934X_NFC_DMA_CTRL_DMA_READY) != 0;
}

static int
ar934x_nfc_wait_dev_ready(struct ar934x_nfc *nfc)
{
        unsigned long timeout;

        timeout = jiffies + msecs_to_jiffies(AR934X_NFC_DEV_READY_TIMEOUT);
        do {
                if (__ar934x_nfc_dev_ready(nfc))
                        return 0;
        } while time_before(jiffies, timeout);

        nfc_dbg(nfc, "timeout waiting for device ready, status:%08x int:%08x\n",
                ar934x_nfc_rr(nfc, AR934X_NFC_REG_STATUS),
                ar934x_nfc_rr(nfc, AR934X_NFC_REG_INT_STATUS));
        return -ETIMEDOUT;
}

static int
ar934x_nfc_wait_dma_ready(struct ar934x_nfc *nfc)
{
        unsigned long timeout;

        timeout = jiffies + msecs_to_jiffies(AR934X_NFC_DMA_READY_TIMEOUT);
        do {
                if (__ar934x_nfc_is_dma_ready(nfc))
                        return 0;
        } while time_before(jiffies, timeout);

        nfc_dbg(nfc, "timeout waiting for DMA ready, dma_ctrl:%08x\n",
                ar934x_nfc_rr(nfc, AR934X_NFC_REG_DMA_CTRL));
        return -ETIMEDOUT;
}

static int
ar934x_nfc_wait_irq(struct ar934x_nfc *nfc)
{
        long timeout;
        int ret;

        timeout = wait_event_timeout(nfc->irq_waitq,
                                (nfc->irq_status & AR934X_NFC_IRQ_MASK) != 0,
                                msecs_to_jiffies(AR934X_NFC_DEV_READY_TIMEOUT));

        ret = 0;
        if (!timeout) {
                ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_MASK, 0);
                ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_STATUS, 0);
                /* flush write */
                ar934x_nfc_rr(nfc, AR934X_NFC_REG_INT_STATUS);

                nfc_dbg(nfc,
                        "timeout waiting for interrupt, status:%08x\n",
                        nfc->irq_status);
                ret = -ETIMEDOUT;
        }

        nfc->irq_status = 0;
        return ret;
}

static int
ar934x_nfc_wait_done(struct ar934x_nfc *nfc)
{
        int ret;

        if (ar934x_nfc_use_irq(nfc))
                ret = ar934x_nfc_wait_irq(nfc);
        else
                ret = ar934x_nfc_wait_dev_ready(nfc);

        if (ret)
                return ret;

        return ar934x_nfc_wait_dma_ready(nfc);
}

static int
ar934x_nfc_alloc_buf(struct ar934x_nfc *nfc, unsigned size)
{
        nfc->buf = dma_alloc_coherent(nfc->parent, size,
                                      &nfc->buf_dma, GFP_KERNEL);
        if (nfc->buf == NULL) {
                dev_err(nfc->parent, "no memory for DMA buffer\n");
                return -ENOMEM;
        }

        nfc->buf_size = size;
        nfc_dbg(nfc, "buf:%p size:%u\n", nfc->buf, nfc->buf_size);

        return 0;
}

static void
ar934x_nfc_free_buf(struct ar934x_nfc *nfc)
{
        dma_free_coherent(nfc->parent, nfc->buf_size, nfc->buf, nfc->buf_dma);
}

static void
ar934x_nfc_get_addr(struct ar934x_nfc *nfc, int column, int page_addr,
                    u32 *addr0, u32 *addr1)
{
        u32 a0, a1;

        a0 = 0;
        a1 = 0;

        if (column == -1) {
                /* ERASE1 */
                a0 = (page_addr & 0xffff) << 16;
                a1 = (page_addr >> 16) & 0xf;
        } else if (page_addr != -1) {
                /* SEQIN, READ0, etc.. */

                /* TODO: handle 16bit bus width */
                if (nfc->small_page) {
                        a0 = column & 0xff;
                        a0 |= (page_addr & 0xff) << 8;
                        a0 |= ((page_addr >> 8) & 0xff) << 16;
                        a0 |= ((page_addr >> 16) & 0xff) << 24;
                } else {
                        a0 = column & 0x0FFF;
                        a0 |= (page_addr & 0xffff) << 16;

                        if (nfc->addr_count0 > 4)
                                a1 = (page_addr >> 16) & 0xf;
                }
        }

        *addr0 = a0;
        *addr1 = a1;
}

static void
ar934x_nfc_send_cmd(struct ar934x_nfc *nfc, unsigned command)
{
        u32 cmd_reg;

        cmd_reg = AR934X_NFC_CMD_INPUT_SEL_SIU | AR934X_NFC_CMD_ADDR_SEL_0 |
                  AR934X_NFC_CMD_SEQ_1C;
        cmd_reg |= (command & AR934X_NFC_CMD_CMD0_M) << AR934X_NFC_CMD_CMD0_S;

        ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_STATUS, 0);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_CTRL, nfc->ctrl_reg);

        ar934x_nfc_write_cmd_reg(nfc, cmd_reg);
        ar934x_nfc_wait_dev_ready(nfc);
}

static int
ar934x_nfc_do_rw_command(struct ar934x_nfc *nfc, int column, int page_addr,
                         int len, u32 cmd_reg, u32 ctrl_reg, bool write)
{
        u32 addr0, addr1;
        u32 dma_ctrl;
        int dir;
        int err;
        int retries = 0;

        WARN_ON(len & 3);

        if (WARN_ON(len > nfc->buf_size))
                dev_err(nfc->parent, "len=%d > buf_size=%d", len, nfc->buf_size);

        if (write) {
                dma_ctrl = AR934X_NFC_DMA_CTRL_DMA_DIR_WRITE;
                dir = DMA_TO_DEVICE;
        } else {
                dma_ctrl = AR934X_NFC_DMA_CTRL_DMA_DIR_READ;
                dir = DMA_FROM_DEVICE;
        }

        ar934x_nfc_get_addr(nfc, column, page_addr, &addr0, &addr1);

        dma_ctrl |= AR934X_NFC_DMA_CTRL_DMA_START |
                    (AR934X_NFC_DMA_CTRL_DMA_BURST_3 <<
                     AR934X_NFC_DMA_CTRL_DMA_BURST_S);

        cmd_reg |= AR934X_NFC_CMD_INPUT_SEL_DMA | AR934X_NFC_CMD_ADDR_SEL_0;
        ctrl_reg |= AR934X_NFC_CTRL_INT_EN;

        nfc_dbg(nfc, "%s a0:%08x a1:%08x len:%x cmd:%08x dma:%08x ctrl:%08x\n",
                (write) ? "write" : "read",
                addr0, addr1, len, cmd_reg, dma_ctrl, ctrl_reg);

retry:
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_STATUS, 0);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_ADDR0_0, addr0);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_ADDR0_1, addr1);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_DMA_ADDR, nfc->buf_dma);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_DMA_COUNT, len);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_DATA_SIZE, len);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_CTRL, ctrl_reg);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_DMA_CTRL, dma_ctrl);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_ECC_CTRL, nfc->ecc_ctrl_reg);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_ECC_OFFSET, nfc->ecc_offset_reg);

        if (ar934x_nfc_use_irq(nfc)) {
                ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_MASK, AR934X_NFC_IRQ_MASK);
                /* flush write */
                ar934x_nfc_rr(nfc, AR934X_NFC_REG_INT_MASK);
        }

        ar934x_nfc_write_cmd_reg(nfc, cmd_reg);
        err = ar934x_nfc_wait_done(nfc);
        if (err) {
                dev_dbg(nfc->parent, "%s operation stuck at page %d\n",
                        (write) ? "write" : "read", page_addr);

                ar934x_nfc_restart(nfc);
                if (retries++ < AR934X_NFC_DMA_RETRIES)
                        goto retry;

                dev_err(nfc->parent, "%s operation failed on page %d\n",
                        (write) ? "write" : "read", page_addr);
        }

        return err;
}

static int
ar934x_nfc_send_readid(struct ar934x_nfc *nfc, unsigned command)
{
        u32 cmd_reg;
        int err;

        nfc_dbg(nfc, "readid, cmd:%02x\n", command);

        cmd_reg = AR934X_NFC_CMD_SEQ_1C1AXR;
        cmd_reg |= (command & AR934X_NFC_CMD_CMD0_M) << AR934X_NFC_CMD_CMD0_S;

        err = ar934x_nfc_do_rw_command(nfc, -1, -1, AR934X_NFC_ID_BUF_SIZE,
                                       cmd_reg, nfc->ctrl_reg, false);

        nfc_debug_data("[id] ", nfc->buf, AR934X_NFC_ID_BUF_SIZE);

        return err;
}

static int
ar934x_nfc_send_read(struct ar934x_nfc *nfc, unsigned command, int column,
                     int page_addr, int len)
{
        u32 cmd_reg;
        int err;

        nfc_dbg(nfc, "read, column=%d page=%d len=%d\n",
                column, page_addr, len);

        cmd_reg = (command & AR934X_NFC_CMD_CMD0_M) << AR934X_NFC_CMD_CMD0_S;

        if (nfc->small_page) {
                cmd_reg |= AR934X_NFC_CMD_SEQ_18;
        } else {
                cmd_reg |= NAND_CMD_READSTART << AR934X_NFC_CMD_CMD1_S;
                cmd_reg |= AR934X_NFC_CMD_SEQ_1C5A1CXR;
        }

        err = ar934x_nfc_do_rw_command(nfc, column, page_addr, len,
                                       cmd_reg, nfc->ctrl_reg, false);

        nfc_debug_data("[data] ", nfc->buf, len);

        return err;
}

static void
ar934x_nfc_send_erase(struct ar934x_nfc *nfc, unsigned command, int column,
                      int page_addr)
{
        u32 addr0, addr1;
        u32 ctrl_reg;
        u32 cmd_reg;

        ar934x_nfc_get_addr(nfc, column, page_addr, &addr0, &addr1);

        ctrl_reg = nfc->ctrl_reg;
        if (nfc->small_page) {
                /* override number of address cycles for the erase command */
                ctrl_reg &= ~(AR934X_NFC_CTRL_ADDR_CYCLE0_M <<
                              AR934X_NFC_CTRL_ADDR_CYCLE0_S);
                ctrl_reg &= ~(AR934X_NFC_CTRL_ADDR_CYCLE1_M <<
                              AR934X_NFC_CTRL_ADDR_CYCLE1_S);
                ctrl_reg &= ~(AR934X_NFC_CTRL_SMALL_PAGE);
                ctrl_reg |= (nfc->addr_count0 + 1) <<
                            AR934X_NFC_CTRL_ADDR_CYCLE0_S;
        }

        cmd_reg = NAND_CMD_ERASE1 << AR934X_NFC_CMD_CMD0_S;
        cmd_reg |= command << AR934X_NFC_CMD_CMD1_S;
        cmd_reg |= AR934X_NFC_CMD_SEQ_ERASE;

        nfc_dbg(nfc, "erase page %d, a0:%08x a1:%08x cmd:%08x ctrl:%08x\n",
                page_addr, addr0, addr1, cmd_reg, ctrl_reg);

        ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_STATUS, 0);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_CTRL, ctrl_reg);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_ADDR0_0, addr0);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_ADDR0_1, addr1);

        ar934x_nfc_write_cmd_reg(nfc, cmd_reg);
        ar934x_nfc_wait_dev_ready(nfc);
}

static int
ar934x_nfc_send_write(struct ar934x_nfc *nfc, unsigned command, int column,
                     int page_addr, int len)
{
        u32 cmd_reg;

        nfc_dbg(nfc, "write, column=%d page=%d len=%d\n",
                column, page_addr, len);

        nfc_debug_data("[data] ", nfc->buf, len);

        cmd_reg = NAND_CMD_SEQIN << AR934X_NFC_CMD_CMD0_S;
        cmd_reg |= command << AR934X_NFC_CMD_CMD1_S;
        cmd_reg |= AR934X_NFC_CMD_SEQ_12;

        return ar934x_nfc_do_rw_command(nfc, column, page_addr, len,
                                        cmd_reg, nfc->ctrl_reg, true);
}

static void
ar934x_nfc_read_status(struct ar934x_nfc *nfc)
{
        u32 cmd_reg;
        u32 status;

        cmd_reg = NAND_CMD_STATUS << AR934X_NFC_CMD_CMD0_S;
        cmd_reg |= AR934X_NFC_CMD_SEQ_S;

        ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_STATUS, 0);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_CTRL, nfc->ctrl_reg);

        ar934x_nfc_write_cmd_reg(nfc, cmd_reg);
        ar934x_nfc_wait_dev_ready(nfc);

        status = ar934x_nfc_rr(nfc, AR934X_NFC_REG_READ_STATUS);

        nfc_dbg(nfc, "read status, cmd:%08x status:%02x\n",
                cmd_reg, (status & 0xff));

        if (nfc->swap_dma)
                nfc->buf[0 ^ 3] = status;
        else
                nfc->buf[0] = status;
}

static void
ar934x_nfc_cmdfunc(struct mtd_info *mtd, unsigned int command, int column,
                   int page_addr)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        struct nand_chip *nand = &nfc->nand_chip;

        nfc->read_id = false;
        if (command != NAND_CMD_PAGEPROG)
                nfc->buf_index = 0;

        switch (command) {
        case NAND_CMD_RESET:
                ar934x_nfc_send_cmd(nfc, command);
                break;

        case NAND_CMD_READID:
                nfc->read_id = true;
                ar934x_nfc_send_readid(nfc, command);
                break;

        case NAND_CMD_READ0:
        case NAND_CMD_READ1:
                if (nfc->small_page) {
                        ar934x_nfc_send_read(nfc, command, column, page_addr,
                                             mtd->writesize + mtd->oobsize);
                } else {
                        ar934x_nfc_send_read(nfc, command, 0, page_addr,
                                             mtd->writesize + mtd->oobsize);
                        nfc->buf_index = column;
                        nfc->rndout_page_addr = page_addr;
                        nfc->rndout_read_cmd = command;
                }
                break;

        case NAND_CMD_READOOB:
                if (nfc->small_page)
                        ar934x_nfc_send_read(nfc, NAND_CMD_READOOB,
                                             column, page_addr,
                                             mtd->oobsize);
                else
                        ar934x_nfc_send_read(nfc, NAND_CMD_READ0,
                                             mtd->writesize, page_addr,
                                             mtd->oobsize);
                break;

        case NAND_CMD_RNDOUT:
                if (WARN_ON(nfc->small_page))
                        break;

                /* emulate subpage read */
                ar934x_nfc_send_read(nfc, nfc->rndout_read_cmd, 0,
                                     nfc->rndout_page_addr,
                                     mtd->writesize + mtd->oobsize);
                nfc->buf_index = column;
                break;

        case NAND_CMD_ERASE1:
                nfc->erase1_page_addr = page_addr;
                break;

        case NAND_CMD_ERASE2:
                ar934x_nfc_send_erase(nfc, command, -1, nfc->erase1_page_addr);
                break;

        case NAND_CMD_STATUS:
                ar934x_nfc_read_status(nfc);
                break;

        case NAND_CMD_SEQIN:
                if (nfc->small_page) {
                        /* output read command */
                        if (column >= mtd->writesize) {
                                column -= mtd->writesize;
                                nfc->seqin_read_cmd = NAND_CMD_READOOB;
                        } else if (column < 256) {
                                nfc->seqin_read_cmd = NAND_CMD_READ0;
                        } else {
                                column -= 256;
                                nfc->seqin_read_cmd = NAND_CMD_READ1;
                        }
                } else {
                        nfc->seqin_read_cmd = NAND_CMD_READ0;
                }
                nfc->seqin_column = column;
                nfc->seqin_page_addr = page_addr;
                break;

        case NAND_CMD_PAGEPROG:
                if (nand->ecc.mode == NAND_ECC_HW) {
                        /* the data is already written */
                        break;
                }

                if (nfc->small_page)
                        ar934x_nfc_send_cmd(nfc, nfc->seqin_read_cmd);

                ar934x_nfc_send_write(nfc, command, nfc->seqin_column,
                                      nfc->seqin_page_addr,
                                      nfc->buf_index);
                break;

        default:
                dev_err(nfc->parent,
                        "unsupported command: %x, column:%d page_addr=%d\n",
                        command, column, page_addr);
                break;
        }
}

static int
ar934x_nfc_dev_ready(struct mtd_info *mtd)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);

        return __ar934x_nfc_dev_ready(nfc);
}

static void
ar934x_nfc_select_chip(struct mtd_info *mtd, int chip_no)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);

        if (nfc->select_chip)
                nfc->select_chip(chip_no);
}

static u8
ar934x_nfc_read_byte(struct mtd_info *mtd)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        u8 data;

        WARN_ON(nfc->buf_index >= nfc->buf_size);

        if (nfc->swap_dma || nfc->read_id)
                data = nfc->buf[nfc->buf_index ^ 3];
        else
                data = nfc->buf[nfc->buf_index];

        nfc->buf_index++;

        return data;
}

static void
ar934x_nfc_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        int i;

        WARN_ON(nfc->buf_index + len > nfc->buf_size);

        if (nfc->swap_dma) {
                for (i = 0; i < len; i++) {
                        nfc->buf[nfc->buf_index ^ 3] = buf[i];
                        nfc->buf_index++;
                }
        } else {
                for (i = 0; i < len; i++) {
                        nfc->buf[nfc->buf_index] = buf[i];
                        nfc->buf_index++;
                }
        }
}

static void
ar934x_nfc_read_buf(struct mtd_info *mtd, u8 *buf, int len)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        int buf_index;
        int i;

        WARN_ON(nfc->buf_index + len > nfc->buf_size);

        buf_index = nfc->buf_index;

        if (nfc->swap_dma || nfc->read_id) {
                for (i = 0; i < len; i++) {
                        buf[i] = nfc->buf[buf_index ^ 3];
                        buf_index++;
                }
        } else {
                for (i = 0; i < len; i++) {
                        buf[i] = nfc->buf[buf_index];
                        buf_index++;
                }
        }

        nfc->buf_index = buf_index;
}

static inline void
ar934x_nfc_enable_hwecc(struct ar934x_nfc *nfc)
{
        nfc->ctrl_reg |= AR934X_NFC_CTRL_ECC_EN;
        nfc->ctrl_reg &= ~AR934X_NFC_CTRL_CUSTOM_SIZE_EN;
}

static inline void
ar934x_nfc_disable_hwecc(struct ar934x_nfc *nfc)
{
        nfc->ctrl_reg &= ~AR934X_NFC_CTRL_ECC_EN;
        nfc->ctrl_reg |= AR934X_NFC_CTRL_CUSTOM_SIZE_EN;
}

static int
ar934x_nfc_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
                    int page)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        int err;

        nfc_dbg(nfc, "read_oob: page:%d\n", page);

        err = ar934x_nfc_send_read(nfc, NAND_CMD_READ0, mtd->writesize, page,
                                   mtd->oobsize);
        if (err)
                return err;

        memcpy(chip->oob_poi, nfc->buf, mtd->oobsize);

        return 0;
}

static int
ar934x_nfc_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
                     int page)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);

        nfc_dbg(nfc, "write_oob: page:%d\n", page);

        memcpy(nfc->buf, chip->oob_poi, mtd->oobsize);

        return ar934x_nfc_send_write(nfc, NAND_CMD_PAGEPROG, mtd->writesize,
                                     page, mtd->oobsize);
}

static int
ar934x_nfc_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                         u8 *buf, int oob_required, int page)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        int len;
        int err;

        nfc_dbg(nfc, "read_page_raw: page:%d oob:%d\n", page, oob_required);

        len = mtd->writesize;
        if (oob_required)
                len += mtd->oobsize;

        err = ar934x_nfc_send_read(nfc, NAND_CMD_READ0, 0, page, len);
        if (err)
                return err;

        memcpy(buf, nfc->buf, mtd->writesize);

        if (oob_required)
                memcpy(chip->oob_poi, &nfc->buf[mtd->writesize], mtd->oobsize);

        return 0;
}

static int
ar934x_nfc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
                     u8 *buf, int oob_required, int page)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        u32 ecc_ctrl;
        int max_bitflips = 0;
        bool ecc_failed;
        bool ecc_corrected;
        int err;

        nfc_dbg(nfc, "read_page: page:%d oob:%d\n", page, oob_required);

        ar934x_nfc_enable_hwecc(nfc);
        err = ar934x_nfc_send_read(nfc, NAND_CMD_READ0, 0, page,
                                   mtd->writesize);
        ar934x_nfc_disable_hwecc(nfc);

        if (err)
                return err;

        /* TODO: optimize to avoid memcpy */
        memcpy(buf, nfc->buf, mtd->writesize);

        /* read the ECC status */
        ecc_ctrl = ar934x_nfc_rr(nfc, AR934X_NFC_REG_ECC_CTRL);
        ecc_failed = ecc_ctrl & AR934X_NFC_ECC_CTRL_ERR_UNCORRECT;
        ecc_corrected = ecc_ctrl & AR934X_NFC_ECC_CTRL_ERR_CORRECT;

        if (oob_required || ecc_failed) {
                err = ar934x_nfc_send_read(nfc, NAND_CMD_READ0, mtd->writesize,
                                           page, mtd->oobsize);
                if (err)
                        return err;

                if (oob_required)
                        memcpy(chip->oob_poi, nfc->buf, mtd->oobsize);
        }

        if (ecc_failed) {
                /*
                 * The hardware ECC engine reports uncorrectable errors
                 * on empty pages. Check the ECC bytes and the data. If
                 * both contains 0xff bytes only, dont report a failure.
                 *
                 * TODO: prebuild a buffer with 0xff bytes and use memcmp
                 * for better performance?
                 */
                if (!is_all_ff(&nfc->buf[nfc->ecc_oob_pos], chip->ecc.total) ||
                    !is_all_ff(buf, mtd->writesize))
                                mtd->ecc_stats.failed++;
        } else if (ecc_corrected) {
                /*
                 * The hardware does not report the exact count of the
                 * corrected bitflips, use assumptions based on the
                 * threshold.
                 */
                if (ecc_ctrl & AR934X_NFC_ECC_CTRL_ERR_OVER) {
                        /*
                         * The number of corrected bitflips exceeds the
                         * threshold. Assume the maximum.
                         */
                        max_bitflips = chip->ecc.strength * chip->ecc.steps;
                } else {
                        max_bitflips = nfc->ecc_thres * chip->ecc.steps;
                }

                mtd->ecc_stats.corrected += max_bitflips;
        }

        return max_bitflips;
}

static int
ar934x_nfc_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                          const u8 *buf, int oob_required, int page)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        int len;

        nfc_dbg(nfc, "write_page_raw: page:%d oob:%d\n", page, oob_required);

        memcpy(nfc->buf, buf, mtd->writesize);
        len = mtd->writesize;

        if (oob_required) {
                memcpy(&nfc->buf[mtd->writesize], chip->oob_poi, mtd->oobsize);
                len += mtd->oobsize;
        }

        return ar934x_nfc_send_write(nfc, NAND_CMD_PAGEPROG, 0, page, len);
}

static int
ar934x_nfc_write_page(struct mtd_info *mtd, struct nand_chip *chip,
                      const u8 *buf, int oob_required, int page)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        int err;

        nfc_dbg(nfc, "write_page: page:%d oob:%d\n", page, oob_required);

        /* write OOB first */
        if (oob_required &&
            !is_all_ff(chip->oob_poi, mtd->oobsize)) {
                err = ar934x_nfc_write_oob(mtd, chip, page);
                if (err)
                        return err;
        }

        /* TODO: optimize to avoid memcopy */
        memcpy(nfc->buf, buf, mtd->writesize);

        ar934x_nfc_enable_hwecc(nfc);
        err = ar934x_nfc_send_write(nfc, NAND_CMD_PAGEPROG, 0, page,
                                    mtd->writesize);
        ar934x_nfc_disable_hwecc(nfc);

        return err;
}

static void
ar934x_nfc_hw_init(struct ar934x_nfc *nfc)
{
        struct ar934x_nfc_platform_data *pdata;

        pdata = ar934x_nfc_get_platform_data(nfc);
        if (pdata->hw_reset) {
                pdata->hw_reset(true);
                pdata->hw_reset(false);
        }

        /*
         * setup timings
         * TODO: make it configurable via platform data
         */
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_TIME_SEQ,
                      AR934X_NFC_TIME_SEQ_DEFAULT);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_TIMINGS_ASYN,
                      AR934X_NFC_TIMINGS_ASYN_DEFAULT);
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_TIMINGS_SYN,
                      AR934X_NFC_TIMINGS_SYN_DEFAULT);

        /* disable WP on all chips, and select chip 0 */
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_MEM_CTRL, 0xff00);

        ar934x_nfc_wr(nfc, AR934X_NFC_REG_DMA_ADDR_OFFS, 0);

        /* initialize Control register */
        nfc->ctrl_reg = AR934X_NFC_CTRL_CUSTOM_SIZE_EN;
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_CTRL, nfc->ctrl_reg);

        if (nfc->small_page) {
                /*  Setup generic sequence register for small page reads. */
                ar934x_nfc_wr(nfc, AR934X_NFC_REG_GEN_SEQ_CTRL,
                              AR934X_NFC_GENSEQ_SMALL_PAGE_READ);
        }
}

static void
ar934x_nfc_restart(struct ar934x_nfc *nfc)
{
        u32 ctrl_reg;

        if (nfc->select_chip)
                nfc->select_chip(-1);

        ctrl_reg = nfc->ctrl_reg;
        ar934x_nfc_hw_init(nfc);
        nfc->ctrl_reg = ctrl_reg;

        if (nfc->select_chip)
                nfc->select_chip(0);

        ar934x_nfc_send_cmd(nfc, NAND_CMD_RESET);
}

static irqreturn_t
ar934x_nfc_irq_handler(int irq, void *data)
{
        struct ar934x_nfc *nfc = data;
        u32 status;

        status = ar934x_nfc_rr(nfc, AR934X_NFC_REG_INT_STATUS);

        ar934x_nfc_wr(nfc, AR934X_NFC_REG_INT_STATUS, 0);
        /* flush write */
        ar934x_nfc_rr(nfc, AR934X_NFC_REG_INT_STATUS);

        status &= ar934x_nfc_rr(nfc, AR934X_NFC_REG_INT_MASK);
        if (status) {
                nfc_dbg(nfc, "got IRQ, status:%08x\n", status);

                nfc->irq_status = status;
                nfc->spurious_irq_expected = true;
                wake_up(&nfc->irq_waitq);
        } else {
                if (nfc->spurious_irq_expected) {
                        nfc->spurious_irq_expected = false;
                } else {
                        dev_warn(nfc->parent, "spurious interrupt\n");
                }
        }

        return IRQ_HANDLED;
}

static int
ar934x_nfc_init_tail(struct mtd_info *mtd)
{
        struct ar934x_nfc *nfc = mtd_to_ar934x_nfc(mtd);
        struct nand_chip *chip = &nfc->nand_chip;
        u32 ctrl;
        u32 t;
        int err;

        switch (mtd->oobsize) {
        case 16:
        case 64:
        case 128:
                ar934x_nfc_wr(nfc, AR934X_NFC_REG_SPARE_SIZE, mtd->oobsize);
                break;

        default:
                dev_err(nfc->parent, "unsupported OOB size: %d bytes\n",
                        mtd->oobsize);
                return -ENXIO;
        }

        ctrl = AR934X_NFC_CTRL_CUSTOM_SIZE_EN;

        switch (mtd->erasesize / mtd->writesize) {
        case 32:
                t = AR934X_NFC_CTRL_BLOCK_SIZE_32;
                break;

        case 64:
                t = AR934X_NFC_CTRL_BLOCK_SIZE_64;
                break;

        case 128:
                t = AR934X_NFC_CTRL_BLOCK_SIZE_128;
                break;

        case 256:
                t = AR934X_NFC_CTRL_BLOCK_SIZE_256;
                break;

        default:
                dev_err(nfc->parent, "unsupported block size: %u\n",
                        mtd->erasesize / mtd->writesize);
                return -ENXIO;
        }

        ctrl |= t << AR934X_NFC_CTRL_BLOCK_SIZE_S;

        switch (mtd->writesize) {
        case 256:
                nfc->small_page = 1;
                t = AR934X_NFC_CTRL_PAGE_SIZE_256;
                break;

        case 512:
                nfc->small_page = 1;
                t = AR934X_NFC_CTRL_PAGE_SIZE_512;
                break;

        case 1024:
                t = AR934X_NFC_CTRL_PAGE_SIZE_1024;
                break;

        case 2048:
                t = AR934X_NFC_CTRL_PAGE_SIZE_2048;
                break;

        case 4096:
                t = AR934X_NFC_CTRL_PAGE_SIZE_4096;
                break;

        case 8192:
                t = AR934X_NFC_CTRL_PAGE_SIZE_8192;
                break;

        case 16384:
                t = AR934X_NFC_CTRL_PAGE_SIZE_16384;
                break;

        default:
                dev_err(nfc->parent, "unsupported write size: %d bytes\n",
                        mtd->writesize);
                return -ENXIO;
        }

        ctrl |= t << AR934X_NFC_CTRL_PAGE_SIZE_S;

        if (nfc->small_page) {
                ctrl |= AR934X_NFC_CTRL_SMALL_PAGE;

                if (chip->chipsize > (32 << 20)) {
                        nfc->addr_count0 = 4;
                        nfc->addr_count1 = 3;
                } else if (chip->chipsize > (2 << 16)) {
                        nfc->addr_count0 = 3;
                        nfc->addr_count1 = 2;
                } else {
                        nfc->addr_count0 = 2;
                        nfc->addr_count1 = 1;
                }
        } else {
                if (chip->chipsize > (128 << 20)) {
                        nfc->addr_count0 = 5;
                        nfc->addr_count1 = 3;
                } else if (chip->chipsize > (8 << 16)) {
                        nfc->addr_count0 = 4;
                        nfc->addr_count1 = 2;
                } else {
                        nfc->addr_count0 = 3;
                        nfc->addr_count1 = 1;
                }
        }

        ctrl |= nfc->addr_count0 << AR934X_NFC_CTRL_ADDR_CYCLE0_S;
        ctrl |= nfc->addr_count1 << AR934X_NFC_CTRL_ADDR_CYCLE1_S;

        nfc->ctrl_reg = ctrl;
        ar934x_nfc_wr(nfc, AR934X_NFC_REG_CTRL, nfc->ctrl_reg);

        ar934x_nfc_free_buf(nfc);
        err = ar934x_nfc_alloc_buf(nfc, mtd->writesize + mtd->oobsize);

        return err;
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
static struct nand_ecclayout ar934x_nfc_oob_64_hwecc = {
        .eccbytes = 28,
        .eccpos = {
                20, 21, 22, 23, 24, 25, 26,
                27, 28, 29, 30, 31, 32, 33,
                34, 35, 36, 37, 38, 39, 40,
                41, 42, 43, 44, 45, 46, 47,
        },
        .oobfree = {
                {
                        .offset = 4,
                        .length = 16,
                },
                {
                        .offset = 48,
                        .length = 16,
                },
        },
};

#else

static int ar934x_nfc_ooblayout_ecc(struct mtd_info *mtd, int section,
                                    struct mtd_oob_region *oobregion)
{
        if (section)
                return -ERANGE;

        oobregion->offset = 20;
        oobregion->length = 28;

        return 0;
}

static int ar934x_nfc_ooblayout_free(struct mtd_info *mtd, int section,
                                     struct mtd_oob_region *oobregion)
{
        switch (section) {
        case 0:
                oobregion->offset = 4;
                oobregion->length = 16;
                return 0;
        case 1:
                oobregion->offset = 48;
                oobregion->length = 16;
                return 0;
        default:
                return -ERANGE;
        }
}

static const struct mtd_ooblayout_ops ar934x_nfc_ecclayout_ops = {
        .ecc = ar934x_nfc_ooblayout_ecc,
        .free = ar934x_nfc_ooblayout_free,
};
#endif /* < 4.6 */

static int
ar934x_nfc_setup_hwecc(struct ar934x_nfc *nfc)
{
        struct nand_chip *nand = &nfc->nand_chip;
        struct mtd_info *mtd = ar934x_nfc_to_mtd(nfc);
        u32 ecc_cap;
        u32 ecc_thres;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,6,0)
        struct mtd_oob_region oobregion;
#endif

        if (!IS_ENABLED(CONFIG_MTD_NAND_AR934X_HW_ECC)) {
                dev_err(nfc->parent, "hardware ECC support is disabled\n");
                return -EINVAL;
        }

        switch (mtd->writesize) {
        case 2048:
                /*
                 * Writing a subpage separately is not supported, because
                 * the controller only does ECC on full-page accesses.
                 */
                nand->options = NAND_NO_SUBPAGE_WRITE;

                nand->ecc.size = 512;
                nand->ecc.bytes = 7;
                nand->ecc.strength = 4;
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
                nand->ecc.layout = &ar934x_nfc_oob_64_hwecc;
#else
                mtd_set_ooblayout(mtd, &ar934x_nfc_ecclayout_ops);
#endif
                break;

        default:
                dev_err(nfc->parent,
                        "hardware ECC is not available for %d byte pages\n",
                        mtd->writesize);
                return -EINVAL;
        }

#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        BUG_ON(!nand->ecc.layout);
#else
        BUG_ON(!mtd->ooblayout->ecc);
#endif

        switch (nand->ecc.strength) {
        case 4:
                ecc_cap = AR934X_NFC_ECC_CTRL_ECC_CAP_4;
                ecc_thres = 4;
                break;

        default:
                dev_err(nfc->parent, "unsupported ECC strength %u\n",
                        nand->ecc.strength);
                return -EINVAL;
        }

        nfc->ecc_thres = ecc_thres;
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        nfc->ecc_oob_pos = nand->ecc.layout->eccpos[0];
#else
        mtd->ooblayout->ecc(mtd, 0, &oobregion);
        nfc->ecc_oob_pos = oobregion.offset;
#endif

        nfc->ecc_ctrl_reg = ecc_cap << AR934X_NFC_ECC_CTRL_ECC_CAP_S;
        nfc->ecc_ctrl_reg |= ecc_thres << AR934X_NFC_ECC_CTRL_ERR_THRES_S;

        nfc->ecc_offset_reg = mtd->writesize + nfc->ecc_oob_pos;

        nand->ecc.mode = NAND_ECC_HW;
        nand->ecc.read_page = ar934x_nfc_read_page;
        nand->ecc.read_page_raw = ar934x_nfc_read_page_raw;
        nand->ecc.write_page = ar934x_nfc_write_page;
        nand->ecc.write_page_raw = ar934x_nfc_write_page_raw;
        nand->ecc.read_oob = ar934x_nfc_read_oob;
        nand->ecc.write_oob = ar934x_nfc_write_oob;

        return 0;
}

static int
ar934x_nfc_probe(struct platform_device *pdev)
{
        static const char *part_probes[] = { "cmdlinepart", NULL, };
        struct ar934x_nfc_platform_data *pdata;
        struct ar934x_nfc *nfc;
        struct resource *res;
        struct mtd_info *mtd;
        struct nand_chip *nand;
        struct mtd_part_parser_data ppdata;
        int ret;

        pdata = pdev->dev.platform_data;
        if (pdata == NULL) {
                dev_err(&pdev->dev, "no platform data defined\n");
                return -EINVAL;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(&pdev->dev, "failed to get I/O memory\n");
                return -EINVAL;
        }

        nfc = devm_kzalloc(&pdev->dev, sizeof(struct ar934x_nfc), GFP_KERNEL);
        if (!nfc) {
                dev_err(&pdev->dev, "failed to allocate driver data\n");
                return -ENOMEM;
        }

        nfc->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(nfc->base)) {
                dev_err(&pdev->dev, "failed to remap I/O memory\n");
                return PTR_ERR(nfc->base);
        }

        nfc->irq = platform_get_irq(pdev, 0);
        if (nfc->irq < 0) {
                dev_err(&pdev->dev, "no IRQ resource specified\n");
                return -EINVAL;
        }

        init_waitqueue_head(&nfc->irq_waitq);
        ret = request_irq(nfc->irq, ar934x_nfc_irq_handler, 0,
                          dev_name(&pdev->dev), nfc);
        if (ret) {
                dev_err(&pdev->dev, "requast_irq failed, err:%d\n", ret);
                return ret;
        }

        nfc->parent = &pdev->dev;
        nfc->select_chip = pdata->select_chip;
        nfc->swap_dma = pdata->swap_dma;

        nand = &nfc->nand_chip;
        mtd = ar934x_nfc_to_mtd(nfc);

#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        mtd->priv = nand;
#endif
        mtd->owner = THIS_MODULE;
        if (pdata->name)
                mtd->name = pdata->name;
        else
                mtd->name = dev_name(&pdev->dev);

        nand->chip_delay = 25;

        nand->dev_ready = ar934x_nfc_dev_ready;
        nand->cmdfunc = ar934x_nfc_cmdfunc;
        nand->read_byte = ar934x_nfc_read_byte;
        nand->write_buf = ar934x_nfc_write_buf;
        nand->read_buf = ar934x_nfc_read_buf;
        nand->select_chip = ar934x_nfc_select_chip;

        ret = ar934x_nfc_alloc_buf(nfc, AR934X_NFC_ID_BUF_SIZE);
        if (ret)
                goto err_free_irq;

        platform_set_drvdata(pdev, nfc);

        ar934x_nfc_hw_init(nfc);

        ret = nand_scan_ident(mtd, 1, NULL);
        if (ret) {
                dev_err(&pdev->dev, "nand_scan_ident failed, err:%d\n", ret);
                goto err_free_buf;
        }

        ret = ar934x_nfc_init_tail(mtd);
        if (ret) {
                dev_err(&pdev->dev, "init tail failed, err:%d\n", ret);
                goto err_free_buf;
        }

        if (pdata->scan_fixup) {
                ret = pdata->scan_fixup(mtd);
                if (ret)
                        goto err_free_buf;
        }

        switch (pdata->ecc_mode) {
        case AR934X_NFC_ECC_SOFT:
                nand->ecc.mode = NAND_ECC_SOFT;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,6,0)
                nand->ecc.algo = NAND_ECC_HAMMING;
#endif
                break;

        case AR934X_NFC_ECC_SOFT_BCH:
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
                nand->ecc.mode = NAND_ECC_SOFT_BCH;
#else
                nand->ecc.mode = NAND_ECC_SOFT;
                nand->ecc.algo = NAND_ECC_BCH;
#endif
                break;

        case AR934X_NFC_ECC_HW:
                ret = ar934x_nfc_setup_hwecc(nfc);
                if (ret)
                        goto err_free_buf;

                break;

        default:
                dev_err(nfc->parent, "unknown ECC mode %d\n", pdata->ecc_mode);
                return -EINVAL;
        }

        ret = nand_scan_tail(mtd);
        if (ret) {
                dev_err(&pdev->dev, "scan tail failed, err:%d\n", ret);
                goto err_free_buf;
        }

        memset(&ppdata, '\0', sizeof(ppdata));
        ret = mtd_device_parse_register(mtd, part_probes, &ppdata,
                                        pdata->parts, pdata->nr_parts);
        if (ret) {
                dev_err(&pdev->dev, "unable to register mtd, err:%d\n", ret);
                goto err_free_buf;
        }

        return 0;

err_free_buf:
        ar934x_nfc_free_buf(nfc);
err_free_irq:
        free_irq(nfc->irq, nfc);
        return ret;
}

static int
ar934x_nfc_remove(struct platform_device *pdev)
{
        struct ar934x_nfc *nfc;
        struct mtd_info *mtd;

        nfc = platform_get_drvdata(pdev);
        if (nfc) {
                mtd = ar934x_nfc_to_mtd(nfc);
                nand_release(mtd);
                ar934x_nfc_free_buf(nfc);
                free_irq(nfc->irq, nfc);
        }

        return 0;
}

static struct platform_driver ar934x_nfc_driver = {
        .probe          = ar934x_nfc_probe,
        .remove         = ar934x_nfc_remove,
        .driver = {
                .name   = AR934X_NFC_DRIVER_NAME,
                .owner  = THIS_MODULE,
        },
};

module_platform_driver(ar934x_nfc_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_DESCRIPTION("Atheros AR934x NAND Flash Controller driver");
MODULE_ALIAS("platform:" AR934X_NFC_DRIVER_NAME);