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/*
 *  NAND flash driver for the MikroTik RouterBoard 4xx series
 *
 *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
 *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
 *
 *  This file was based on the driver for Linux 2.6.22 published by
 *  MikroTik for their RouterBoard 4xx series devices.
 *
 *  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/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/version.h>

#include <asm/mach-ath79/ath79.h>
#include <asm/mach-ath79/rb4xx_cpld.h>

#define DRV_NAME        "rb4xx-nand"
#define DRV_VERSION     "0.2.0"
#define DRV_DESC        "NAND flash driver for RouterBoard 4xx series"

#define RB4XX_NAND_GPIO_READY   5
#define RB4XX_NAND_GPIO_ALE     37
#define RB4XX_NAND_GPIO_CLE     38
#define RB4XX_NAND_GPIO_NCE     39

struct rb4xx_nand_info {
        struct nand_chip        chip;
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        struct mtd_info         mtd;
#endif
};

static inline struct rb4xx_nand_info *mtd_to_rbinfo(struct mtd_info *mtd)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        return container_of(mtd, struct rb4xx_nand_info, mtd);
#else
        struct nand_chip *chip = mtd_to_nand(mtd);

        return container_of(chip, struct rb4xx_nand_info, chip);
#endif
}

static struct mtd_info *rbinfo_to_mtd(struct rb4xx_nand_info *nfc)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        return &nfc->mtd;
#else
        return nand_to_mtd(&nfc->chip);
#endif
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
/*
 * We need to use the OLD Yaffs-1 OOB layout, otherwise the RB bootloader
 * will not be able to find the kernel that we load.
 */
static struct nand_ecclayout rb4xx_nand_ecclayout = {
        .eccbytes       = 6,
        .eccpos         = { 8, 9, 10, 13, 14, 15 },
        .oobavail       = 9,
        .oobfree        = { { 0, 4 }, { 6, 2 }, { 11, 2 }, { 4, 1 } }
};

#else

static int rb4xx_ooblayout_ecc(struct mtd_info *mtd, int section,
                               struct mtd_oob_region *oobregion)
{
        switch (section) {
        case 0:
                oobregion->offset = 8;
                oobregion->length = 3;
                return 0;
        case 1:
                oobregion->offset = 13;
                oobregion->length = 3;
                return 0;
        default:
                return -ERANGE;
        }
}

static int rb4xx_ooblayout_free(struct mtd_info *mtd, int section,
                                struct mtd_oob_region *oobregion)
{
        switch (section) {
        case 0:
                oobregion->offset = 0;
                oobregion->length = 4;
                return 0;
        case 1:
                oobregion->offset = 4;
                oobregion->length = 1;
                return 0;
        case 2:
                oobregion->offset = 6;
                oobregion->length = 2;
                return 0;
        case 3:
                oobregion->offset = 11;
                oobregion->length = 2;
                return 0;
        default:
                return -ERANGE;
        }
}

static const struct mtd_ooblayout_ops rb4xx_nand_ecclayout_ops = {
        .ecc = rb4xx_ooblayout_ecc,
        .free = rb4xx_ooblayout_free,
};
#endif /* < 4.6 */

static struct mtd_partition rb4xx_nand_partitions[] = {
        {
                .name   = "booter",
                .offset = 0,
                .size   = (256 * 1024),
                .mask_flags = MTD_WRITEABLE,
        },
        {
                .name   = "kernel",
                .offset = (256 * 1024),
                .size   = (4 * 1024 * 1024) - (256 * 1024),
        },
        {
                .name   = "ubi",
                .offset = MTDPART_OFS_NXTBLK,
                .size   = MTDPART_SIZ_FULL,
        },
};

static int rb4xx_nand_dev_ready(struct mtd_info *mtd)
{
        return gpio_get_value_cansleep(RB4XX_NAND_GPIO_READY);
}

static void rb4xx_nand_write_cmd(unsigned char cmd)
{
        unsigned char data = cmd;
        int err;

        err = rb4xx_cpld_write(&data, 1);
        if (err)
                pr_err("rb4xx_nand: write cmd failed, err=%d\n", err);
}

static void rb4xx_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
                                unsigned int ctrl)
{
        if (ctrl & NAND_CTRL_CHANGE) {
                gpio_set_value_cansleep(RB4XX_NAND_GPIO_CLE,
                                        (ctrl & NAND_CLE) ? 1 : 0);
                gpio_set_value_cansleep(RB4XX_NAND_GPIO_ALE,
                                        (ctrl & NAND_ALE) ? 1 : 0);
                gpio_set_value_cansleep(RB4XX_NAND_GPIO_NCE,
                                        (ctrl & NAND_NCE) ? 0 : 1);
        }

        if (cmd != NAND_CMD_NONE)
                rb4xx_nand_write_cmd(cmd);
}

static unsigned char rb4xx_nand_read_byte(struct mtd_info *mtd)
{
        unsigned char data = 0;
        int err;

        err = rb4xx_cpld_read(&data, 1);
        if (err) {
                pr_err("rb4xx_nand: read data failed, err=%d\n", err);
                data = 0xff;
        }

        return data;
}

static void rb4xx_nand_write_buf(struct mtd_info *mtd, const unsigned char *buf,
                                 int len)
{
        int err;

        err = rb4xx_cpld_write(buf, len);
        if (err)
                pr_err("rb4xx_nand: write buf failed, err=%d\n", err);
}

static void rb4xx_nand_read_buf(struct mtd_info *mtd, unsigned char *buf,
                                int len)
{
        int err;

        err = rb4xx_cpld_read(buf, len);
        if (err)
                pr_err("rb4xx_nand: read buf failed, err=%d\n", err);
}

static int rb4xx_nand_probe(struct platform_device *pdev)
{
        struct rb4xx_nand_info  *info;
        struct mtd_info *mtd;
        int ret;

        printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");

        ret = gpio_request(RB4XX_NAND_GPIO_READY, "NAND RDY");
        if (ret) {
                dev_err(&pdev->dev, "unable to request gpio %d\n",
                        RB4XX_NAND_GPIO_READY);
                goto err;
        }

        ret = gpio_direction_input(RB4XX_NAND_GPIO_READY);
        if (ret) {
                dev_err(&pdev->dev, "unable to set input mode on gpio %d\n",
                        RB4XX_NAND_GPIO_READY);
                goto err_free_gpio_ready;
        }

        ret = gpio_request(RB4XX_NAND_GPIO_ALE, "NAND ALE");
        if (ret) {
                dev_err(&pdev->dev, "unable to request gpio %d\n",
                        RB4XX_NAND_GPIO_ALE);
                goto err_free_gpio_ready;
        }

        ret = gpio_direction_output(RB4XX_NAND_GPIO_ALE, 0);
        if (ret) {
                dev_err(&pdev->dev, "unable to set output mode on gpio %d\n",
                        RB4XX_NAND_GPIO_ALE);
                goto err_free_gpio_ale;
        }

        ret = gpio_request(RB4XX_NAND_GPIO_CLE, "NAND CLE");
        if (ret) {
                dev_err(&pdev->dev, "unable to request gpio %d\n",
                        RB4XX_NAND_GPIO_CLE);
                goto err_free_gpio_ale;
        }

        ret = gpio_direction_output(RB4XX_NAND_GPIO_CLE, 0);
        if (ret) {
                dev_err(&pdev->dev, "unable to set output mode on gpio %d\n",
                        RB4XX_NAND_GPIO_CLE);
                goto err_free_gpio_cle;
        }

        ret = gpio_request(RB4XX_NAND_GPIO_NCE, "NAND NCE");
        if (ret) {
                dev_err(&pdev->dev, "unable to request gpio %d\n",
                        RB4XX_NAND_GPIO_NCE);
                goto err_free_gpio_cle;
        }

        ret = gpio_direction_output(RB4XX_NAND_GPIO_NCE, 1);
        if (ret) {
                dev_err(&pdev->dev, "unable to set output mode on gpio %d\n",
                        RB4XX_NAND_GPIO_ALE);
                goto err_free_gpio_nce;
        }

        info = kzalloc(sizeof(*info), GFP_KERNEL);
        if (!info) {
                dev_err(&pdev->dev, "rb4xx-nand: no memory for private data\n");
                ret = -ENOMEM;
                goto err_free_gpio_nce;
        }

        info->chip.priv = &info;
        mtd = rbinfo_to_mtd(info);

#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
        mtd->priv       = &info->chip;
#endif
        mtd->owner      = THIS_MODULE;

        info->chip.cmd_ctrl     = rb4xx_nand_cmd_ctrl;
        info->chip.dev_ready    = rb4xx_nand_dev_ready;
        info->chip.read_byte    = rb4xx_nand_read_byte;
        info->chip.write_buf    = rb4xx_nand_write_buf;
        info->chip.read_buf     = rb4xx_nand_read_buf;

        info->chip.chip_delay   = 25;
        info->chip.ecc.mode     = NAND_ECC_SOFT;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,6,0)
        info->chip.ecc.algo = NAND_ECC_HAMMING;
#endif
        info->chip.options = NAND_NO_SUBPAGE_WRITE;

        platform_set_drvdata(pdev, info);

        ret = nand_scan_ident(mtd, 1, NULL);
        if (ret) {
                ret = -ENXIO;
                goto err_free_info;
        }

        if (mtd->writesize == 512)
#if LINUX_VERSION_CODE < KERNEL_VERSION(4,6,0)
                info->chip.ecc.layout = &rb4xx_nand_ecclayout;
#else
                mtd_set_ooblayout(mtd, &rb4xx_nand_ecclayout_ops);
#endif

        ret = nand_scan_tail(mtd);
        if (ret) {
                return -ENXIO;
                goto err_set_drvdata;
        }

        mtd_device_register(mtd, rb4xx_nand_partitions,
                                ARRAY_SIZE(rb4xx_nand_partitions));
        if (ret)
                goto err_release_nand;

        return 0;

err_release_nand:
        nand_release(mtd);
err_set_drvdata:
        platform_set_drvdata(pdev, NULL);
err_free_info:
        kfree(info);
err_free_gpio_nce:
        gpio_free(RB4XX_NAND_GPIO_NCE);
err_free_gpio_cle:
        gpio_free(RB4XX_NAND_GPIO_CLE);
err_free_gpio_ale:
        gpio_free(RB4XX_NAND_GPIO_ALE);
err_free_gpio_ready:
        gpio_free(RB4XX_NAND_GPIO_READY);
err:
        return ret;
}

static int rb4xx_nand_remove(struct platform_device *pdev)
{
        struct rb4xx_nand_info *info = platform_get_drvdata(pdev);

        nand_release(rbinfo_to_mtd(info));
        platform_set_drvdata(pdev, NULL);
        kfree(info);
        gpio_free(RB4XX_NAND_GPIO_NCE);
        gpio_free(RB4XX_NAND_GPIO_CLE);
        gpio_free(RB4XX_NAND_GPIO_ALE);
        gpio_free(RB4XX_NAND_GPIO_READY);

        return 0;
}

static struct platform_driver rb4xx_nand_driver = {
        .probe  = rb4xx_nand_probe,
        .remove = rb4xx_nand_remove,
        .driver = {
                .name   = DRV_NAME,
                .owner  = THIS_MODULE,
        },
};

static int __init rb4xx_nand_init(void)
{
        return platform_driver_register(&rb4xx_nand_driver);
}

static void __exit rb4xx_nand_exit(void)
{
        platform_driver_unregister(&rb4xx_nand_driver);
}

module_init(rb4xx_nand_init);
module_exit(rb4xx_nand_exit);

MODULE_DESCRIPTION(DRV_DESC);
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org>");
MODULE_LICENSE("GPL v2");