/*
 * Copyright © 2004-2008 Simtec Electronics
 *	http://armlinux.simtec.co.uk/
 *	Ben Dooks <ben@simtec.co.uk>
 *
 * Samsung S3C2410/S3C2440/S3C2412 NAND driver
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#define pr_fmt(fmt) "nand-s3c2410: " fmt

#ifdef CONFIG_MTD_NAND_S3C2410_DEBUG
#define DEBUG
#endif

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/cpufreq.h>
#include <linux/of.h>
#include <linux/of_device.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/mtd/partitions.h>

#include <linux/platform_data/mtd-nand-s3c2410.h>

#define S3C2410_NFREG(x) (x)

#define S3C2410_NFCONF		S3C2410_NFREG(0x00)
#define S3C2410_NFCMD		S3C2410_NFREG(0x04)
#define S3C2410_NFADDR		S3C2410_NFREG(0x08)
#define S3C2410_NFDATA		S3C2410_NFREG(0x0C)
#define S3C2410_NFSTAT		S3C2410_NFREG(0x10)
#define S3C2410_NFECC		S3C2410_NFREG(0x14)
#define S3C2440_NFCONT		S3C2410_NFREG(0x04)
#define S3C2440_NFCMD		S3C2410_NFREG(0x08)
#define S3C2440_NFADDR		S3C2410_NFREG(0x0C)
#define S3C2440_NFDATA		S3C2410_NFREG(0x10)
#define S3C2440_NFSTAT		S3C2410_NFREG(0x20)
#define S3C2440_NFMECC0		S3C2410_NFREG(0x2C)
#define S3C2412_NFSTAT		S3C2410_NFREG(0x28)
#define S3C2412_NFMECC0		S3C2410_NFREG(0x34)
#define S3C2410_NFCONF_EN		(1<<15)
#define S3C2410_NFCONF_INITECC		(1<<12)
#define S3C2410_NFCONF_nFCE		(1<<11)
#define S3C2410_NFCONF_TACLS(x)		((x)<<8)
#define S3C2410_NFCONF_TWRPH0(x)	((x)<<4)
#define S3C2410_NFCONF_TWRPH1(x)	((x)<<0)
#define S3C2410_NFSTAT_BUSY		(1<<0)
#define S3C2440_NFCONF_TACLS(x)		((x)<<12)
#define S3C2440_NFCONF_TWRPH0(x)	((x)<<8)
#define S3C2440_NFCONF_TWRPH1(x)	((x)<<4)
#define S3C2440_NFCONT_INITECC		(1<<4)
#define S3C2440_NFCONT_nFCE		(1<<1)
#define S3C2440_NFCONT_ENABLE		(1<<0)
#define S3C2440_NFSTAT_READY		(1<<0)
#define S3C2412_NFCONF_NANDBOOT		(1<<31)
#define S3C2412_NFCONT_INIT_MAIN_ECC	(1<<5)
#define S3C2412_NFCONT_nFCE0		(1<<1)
#define S3C2412_NFSTAT_READY		(1<<0)

/* new oob placement block for use with hardware ecc generation
 */
static int s3c2410_ooblayout_ecc(struct mtd_info *mtd, int section,
				 struct mtd_oob_region *oobregion)
{
	if (section)
		return -ERANGE;

	oobregion->offset = 0;
	oobregion->length = 3;

	return 0;
}

static int s3c2410_ooblayout_free(struct mtd_info *mtd, int section,
				  struct mtd_oob_region *oobregion)
{
	if (section)
		return -ERANGE;

	oobregion->offset = 8;
	oobregion->length = 8;

	return 0;
}

static const struct mtd_ooblayout_ops s3c2410_ooblayout_ops = {
	.ecc = s3c2410_ooblayout_ecc,
	.free = s3c2410_ooblayout_free,
};

/* controller and mtd information */

struct s3c2410_nand_info;

/**
 * struct s3c2410_nand_mtd - driver MTD structure
 * @mtd: The MTD instance to pass to the MTD layer.
 * @chip: The NAND chip information.
 * @set: The platform information supplied for this set of NAND chips.
 * @info: Link back to the hardware information.
*/
struct s3c2410_nand_mtd {
	struct nand_chip		chip;
	struct s3c2410_nand_set		*set;
	struct s3c2410_nand_info	*info;
};

enum s3c_cpu_type {
	TYPE_S3C2410,
	TYPE_S3C2412,
	TYPE_S3C2440,
};

enum s3c_nand_clk_state {
	CLOCK_DISABLE	= 0,
	CLOCK_ENABLE,
	CLOCK_SUSPEND,
};

/* overview of the s3c2410 nand state */

/**
 * struct s3c2410_nand_info - NAND controller state.
 * @mtds: An array of MTD instances on this controoler.
 * @platform: The platform data for this board.
 * @device: The platform device we bound to.
 * @clk: The clock resource for this controller.
 * @regs: The area mapped for the hardware registers.
 * @sel_reg: Pointer to the register controlling the NAND selection.
 * @sel_bit: The bit in @sel_reg to select the NAND chip.
 * @mtd_count: The number of MTDs created from this controller.
 * @save_sel: The contents of @sel_reg to be saved over suspend.
 * @clk_rate: The clock rate from @clk.
 * @clk_state: The current clock state.
 * @cpu_type: The exact type of this controller.
 */
struct s3c2410_nand_info {
	/* mtd info */
	struct nand_controller		controller;
	struct s3c2410_nand_mtd		*mtds;
	struct s3c2410_platform_nand	*platform;

	/* device info */
	struct device			*device;
	struct clk			*clk;
	void __iomem			*regs;
	void __iomem			*sel_reg;
	int				sel_bit;
	int				mtd_count;
	unsigned long			save_sel;
	unsigned long			clk_rate;
	enum s3c_nand_clk_state		clk_state;

	enum s3c_cpu_type		cpu_type;

#ifdef CONFIG_ARM_S3C24XX_CPUFREQ
	struct notifier_block	freq_transition;
#endif
};

struct s3c24XX_nand_devtype_data {
	enum s3c_cpu_type type;
};

static const struct s3c24XX_nand_devtype_data s3c2410_nand_devtype_data = {
	.type = TYPE_S3C2410,
};

static const struct s3c24XX_nand_devtype_data s3c2412_nand_devtype_data = {
	.type = TYPE_S3C2412,
};

static const struct s3c24XX_nand_devtype_data s3c2440_nand_devtype_data = {
	.type = TYPE_S3C2440,
};

/* conversion functions */

static struct s3c2410_nand_mtd *s3c2410_nand_mtd_toours(struct mtd_info *mtd)
{
	return container_of(mtd_to_nand(mtd), struct s3c2410_nand_mtd,
			    chip);
}

static struct s3c2410_nand_info *s3c2410_nand_mtd_toinfo(struct mtd_info *mtd)
{
	return s3c2410_nand_mtd_toours(mtd)->info;
}

static struct s3c2410_nand_info *to_nand_info(struct platform_device *dev)
{
	return platform_get_drvdata(dev);
}

static struct s3c2410_platform_nand *to_nand_plat(struct platform_device *dev)
{
	return dev_get_platdata(&dev->dev);
}

static inline int allow_clk_suspend(struct s3c2410_nand_info *info)
{
#ifdef CONFIG_MTD_NAND_S3C2410_CLKSTOP
	return 1;
#else
	return 0;
#endif
}

/**
 * s3c2410_nand_clk_set_state - Enable, disable or suspend NAND clock.
 * @info: The controller instance.
 * @new_state: State to which clock should be set.
 */
static void s3c2410_nand_clk_set_state(struct s3c2410_nand_info *info,
		enum s3c_nand_clk_state new_state)
{
	if (!allow_clk_suspend(info) && new_state == CLOCK_SUSPEND)
		return;

	if (info->clk_state == CLOCK_ENABLE) {
		if (new_state != CLOCK_ENABLE)
			clk_disable_unprepare(info->clk);
	} else {
		if (new_state == CLOCK_ENABLE)
			clk_prepare_enable(info->clk);
	}

	info->clk_state = new_state;
}

/* timing calculations */

#define NS_IN_KHZ 1000000

/**
 * s3c_nand_calc_rate - calculate timing data.
 * @wanted: The cycle time in nanoseconds.
 * @clk: The clock rate in kHz.
 * @max: The maximum divider value.
 *
 * Calculate the timing value from the given parameters.
 */
static int s3c_nand_calc_rate(int wanted, unsigned long clk, int max)
{
	int result;

	result = DIV_ROUND_UP((wanted * clk), NS_IN_KHZ);

	pr_debug("result %d from %ld, %d\n", result, clk, wanted);

	if (result > max) {
		pr_err("%d ns is too big for current clock rate %ld\n",
			wanted, clk);
		return -1;
	}

	if (result < 1)
		result = 1;

	return result;
}

#define to_ns(ticks, clk) (((ticks) * NS_IN_KHZ) / (unsigned int)(clk))

/* controller setup */

/**
 * s3c2410_nand_setrate - setup controller timing information.
 * @info: The controller instance.
 *
 * Given the information supplied by the platform, calculate and set
 * the necessary timing registers in the hardware to generate the
 * necessary timing cycles to the hardware.
 */
static int s3c2410_nand_setrate(struct s3c2410_nand_info *info)
{
	struct s3c2410_platform_nand *plat = info->platform;
	int tacls_max = (info->cpu_type == TYPE_S3C2412) ? 8 : 4;
	int tacls, twrph0, twrph1;
	unsigned long clkrate = clk_get_rate(info->clk);
	unsigned long uninitialized_var(set), cfg, uninitialized_var(mask);
	unsigned long flags;

	/* calculate the timing information for the controller */

	info->clk_rate = clkrate;
	clkrate /= 1000;	/* turn clock into kHz for ease of use */

	if (plat != NULL) {
		tacls = s3c_nand_calc_rate(plat->tacls, clkrate, tacls_max);
		twrph0 = s3c_nand_calc_rate(plat->twrph0, clkrate, 8);
		twrph1 = s3c_nand_calc_rate(plat->twrph1, clkrate, 8);
	} else {
		/* default timings */
		tacls = tacls_max;
		twrph0 = 8;
		twrph1 = 8;
	}

	if (tacls < 0 || twrph0 < 0 || twrph1 < 0) {
		dev_err(info->device, "cannot get suitable timings\n");
		return -EINVAL;
	}

	dev_info(info->device, "Tacls=%d, %dns Twrph0=%d %dns, Twrph1=%d %dns\n",
		tacls, to_ns(tacls, clkrate), twrph0, to_ns(twrph0, clkrate),
						twrph1, to_ns(twrph1, clkrate));

	switch (info->cpu_type) {
	case TYPE_S3C2410:
		mask = (S3C2410_NFCONF_TACLS(3) |
			S3C2410_NFCONF_TWRPH0(7) |
			S3C2410_NFCONF_TWRPH1(7));
		set = S3C2410_NFCONF_EN;
		set |= S3C2410_NFCONF_TACLS(tacls - 1);
		set |= S3C2410_NFCONF_TWRPH0(twrph0 - 1);
		set |= S3C2410_NFCONF_TWRPH1(twrph1 - 1);
		break;

	case TYPE_S3C2440:
	case TYPE_S3C2412:
		mask = (S3C2440_NFCONF_TACLS(tacls_max - 1) |
			S3C2440_NFCONF_TWRPH0(7) |
			S3C2440_NFCONF_TWRPH1(7));

		set = S3C2440_NFCONF_TACLS(tacls - 1);
		set |= S3C2440_NFCONF_TWRPH0(twrph0 - 1);
		set |= S3C2440_NFCONF_TWRPH1(twrph1 - 1);
		break;

	default:
		BUG();
	}

	local_irq_save(flags);

	cfg = readl(info->regs + S3C2410_NFCONF);
	cfg &= ~mask;
	cfg |= set;
	writel(cfg, info->regs + S3C2410_NFCONF);

	local_irq_restore(flags);

	dev_dbg(info->device, "NF_CONF is 0x%lx\n", cfg);

	return 0;
}

/**
 * s3c2410_nand_inithw - basic hardware initialisation
 * @info: The hardware state.
 *
 * Do the basic initialisation of the hardware, using s3c2410_nand_setrate()
 * to setup the hardware access speeds and set the controller to be enabled.
*/
static int s3c2410_nand_inithw(struct s3c2410_nand_info *info)
{
	int ret;

	ret = s3c2410_nand_setrate(info);
	if (ret < 0)
		return ret;

	switch (info->cpu_type) {
	case TYPE_S3C2410:
	default:
		break;

	case TYPE_S3C2440:
	case TYPE_S3C2412:
		/* enable the controller and de-assert nFCE */

		writel(S3C2440_NFCONT_ENABLE, info->regs + S3C2440_NFCONT);
	}

	return 0;
}

/**
 * s3c2410_nand_select_chip - select the given nand chip
 * @this: NAND chip object.
 * @chip: The chip number.
 *
 * This is called by the MTD layer to either select a given chip for the
 * @mtd instance, or to indicate that the access has finished and the
 * chip can be de-selected.
 *
 * The routine ensures that the nFCE line is correctly setup, and any
 * platform specific selection code is called to route nFCE to the specific
 * chip.
 */
static void s3c2410_nand_select_chip(struct nand_chip *this, int chip)
{
	struct s3c2410_nand_info *info;
	struct s3c2410_nand_mtd *nmtd;
	unsigned long cur;

	nmtd = nand_get_controller_data(this);
	info = nmtd->info;

	if (chip != -1)
		s3c2410_nand_clk_set_state(info, CLOCK_ENABLE);

	cur = readl(info->sel_reg);

	if (chip == -1) {
		cur |= info->sel_bit;
	} else {
		if (nmtd->set != NULL && chip > nmtd->set->nr_chips) {
			dev_err(info->device, "invalid chip %d\n", chip);
			return;
		}

		if (info->platform != NULL) {
			if (info->platform->select_chip != NULL)
				(info->platform->select_chip) (nmtd->set, chip);
		}

		cur &= ~info->sel_bit;
	}

	writel(cur, info->sel_reg);

	if (chip == -1)
		s3c2410_nand_clk_set_state(info, CLOCK_SUSPEND);
}

/* s3c2410_nand_hwcontrol
 *
 * Issue command and address cycles to the chip
*/

static void s3c2410_nand_hwcontrol(struct nand_chip *chip, int cmd,
				   unsigned int ctrl)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);

	if (cmd == NAND_CMD_NONE)
		return;

	if (ctrl & NAND_CLE)
		writeb(cmd, info->regs + S3C2410_NFCMD);
	else
		writeb(cmd, info->regs + S3C2410_NFADDR);
}

/* command and control functions */

static void s3c2440_nand_hwcontrol(struct nand_chip *chip, int cmd,
				   unsigned int ctrl)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);

	if (cmd == NAND_CMD_NONE)
		return;

	if (ctrl & NAND_CLE)
		writeb(cmd, info->regs + S3C2440_NFCMD);
	else
		writeb(cmd, info->regs + S3C2440_NFADDR);
}

/* s3c2410_nand_devready()
 *
 * returns 0 if the nand is busy, 1 if it is ready
*/

static int s3c2410_nand_devready(struct nand_chip *chip)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	return readb(info->regs + S3C2410_NFSTAT) & S3C2410_NFSTAT_BUSY;
}

static int s3c2440_nand_devready(struct nand_chip *chip)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	return readb(info->regs + S3C2440_NFSTAT) & S3C2440_NFSTAT_READY;
}

static int s3c2412_nand_devready(struct nand_chip *chip)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	return readb(info->regs + S3C2412_NFSTAT) & S3C2412_NFSTAT_READY;
}

/* ECC handling functions */

static int s3c2410_nand_correct_data(struct nand_chip *chip, u_char *dat,
				     u_char *read_ecc, u_char *calc_ecc)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	unsigned int diff0, diff1, diff2;
	unsigned int bit, byte;

	pr_debug("%s(%p,%p,%p,%p)\n", __func__, mtd, dat, read_ecc, calc_ecc);

	diff0 = read_ecc[0] ^ calc_ecc[0];
	diff1 = read_ecc[1] ^ calc_ecc[1];
	diff2 = read_ecc[2] ^ calc_ecc[2];

	pr_debug("%s: rd %*phN calc %*phN diff %02x%02x%02x\n",
		 __func__, 3, read_ecc, 3, calc_ecc,
		 diff0, diff1, diff2);

	if (diff0 == 0 && diff1 == 0 && diff2 == 0)
		return 0;		/* ECC is ok */

	/* sometimes people do not think about using the ECC, so check
	 * to see if we have an 0xff,0xff,0xff read ECC and then ignore
	 * the error, on the assumption that this is an un-eccd page.
	 */
	if (read_ecc[0] == 0xff && read_ecc[1] == 0xff && read_ecc[2] == 0xff
	    && info->platform->ignore_unset_ecc)
		return 0;

	/* Can we correct this ECC (ie, one row and column change).
	 * Note, this is similar to the 256 error code on smartmedia */

	if (((diff0 ^ (diff0 >> 1)) & 0x55) == 0x55 &&
	    ((diff1 ^ (diff1 >> 1)) & 0x55) == 0x55 &&
	    ((diff2 ^ (diff2 >> 1)) & 0x55) == 0x55) {
		/* calculate the bit position of the error */

		bit  = ((diff2 >> 3) & 1) |
		       ((diff2 >> 4) & 2) |
		       ((diff2 >> 5) & 4);

		/* calculate the byte position of the error */

		byte = ((diff2 << 7) & 0x100) |
		       ((diff1 << 0) & 0x80)  |
		       ((diff1 << 1) & 0x40)  |
		       ((diff1 << 2) & 0x20)  |
		       ((diff1 << 3) & 0x10)  |
		       ((diff0 >> 4) & 0x08)  |
		       ((diff0 >> 3) & 0x04)  |
		       ((diff0 >> 2) & 0x02)  |
		       ((diff0 >> 1) & 0x01);

		dev_dbg(info->device, "correcting error bit %d, byte %d\n",
			bit, byte);

		dat[byte] ^= (1 << bit);
		return 1;
	}

	/* if there is only one bit difference in the ECC, then
	 * one of only a row or column parity has changed, which
	 * means the error is most probably in the ECC itself */

	diff0 |= (diff1 << 8);
	diff0 |= (diff2 << 16);

	/* equal to "(diff0 & ~(1 << __ffs(diff0)))" */
	if ((diff0 & (diff0 - 1)) == 0)
		return 1;

	return -1;
}

/* ECC functions
 *
 * These allow the s3c2410 and s3c2440 to use the controller's ECC
 * generator block to ECC the data as it passes through]
*/

static void s3c2410_nand_enable_hwecc(struct nand_chip *chip, int mode)
{
	struct s3c2410_nand_info *info;
	unsigned long ctrl;

	info = s3c2410_nand_mtd_toinfo(nand_to_mtd(chip));
	ctrl = readl(info->regs + S3C2410_NFCONF);
	ctrl |= S3C2410_NFCONF_INITECC;
	writel(ctrl, info->regs + S3C2410_NFCONF);
}

static void s3c2412_nand_enable_hwecc(struct nand_chip *chip, int mode)
{
	struct s3c2410_nand_info *info;
	unsigned long ctrl;

	info = s3c2410_nand_mtd_toinfo(nand_to_mtd(chip));
	ctrl = readl(info->regs + S3C2440_NFCONT);
	writel(ctrl | S3C2412_NFCONT_INIT_MAIN_ECC,
	       info->regs + S3C2440_NFCONT);
}

static void s3c2440_nand_enable_hwecc(struct nand_chip *chip, int mode)
{
	struct s3c2410_nand_info *info;
	unsigned long ctrl;

	info = s3c2410_nand_mtd_toinfo(nand_to_mtd(chip));
	ctrl = readl(info->regs + S3C2440_NFCONT);
	writel(ctrl | S3C2440_NFCONT_INITECC, info->regs + S3C2440_NFCONT);
}

static int s3c2410_nand_calculate_ecc(struct nand_chip *chip,
				      const u_char *dat, u_char *ecc_code)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);

	ecc_code[0] = readb(info->regs + S3C2410_NFECC + 0);
	ecc_code[1] = readb(info->regs + S3C2410_NFECC + 1);
	ecc_code[2] = readb(info->regs + S3C2410_NFECC + 2);

	pr_debug("%s: returning ecc %*phN\n", __func__, 3, ecc_code);

	return 0;
}

static int s3c2412_nand_calculate_ecc(struct nand_chip *chip,
				      const u_char *dat, u_char *ecc_code)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	unsigned long ecc = readl(info->regs + S3C2412_NFMECC0);

	ecc_code[0] = ecc;
	ecc_code[1] = ecc >> 8;
	ecc_code[2] = ecc >> 16;

	pr_debug("%s: returning ecc %*phN\n", __func__, 3, ecc_code);

	return 0;
}

static int s3c2440_nand_calculate_ecc(struct nand_chip *chip,
				      const u_char *dat, u_char *ecc_code)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	unsigned long ecc = readl(info->regs + S3C2440_NFMECC0);

	ecc_code[0] = ecc;
	ecc_code[1] = ecc >> 8;
	ecc_code[2] = ecc >> 16;

	pr_debug("%s: returning ecc %06lx\n", __func__, ecc & 0xffffff);

	return 0;
}

/* over-ride the standard functions for a little more speed. We can
 * use read/write block to move the data buffers to/from the controller
*/

static void s3c2410_nand_read_buf(struct nand_chip *this, u_char *buf, int len)
{
	readsb(this->legacy.IO_ADDR_R, buf, len);
}

static void s3c2440_nand_read_buf(struct nand_chip *this, u_char *buf, int len)
{
	struct mtd_info *mtd = nand_to_mtd(this);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);

	readsl(info->regs + S3C2440_NFDATA, buf, len >> 2);

	/* cleanup if we've got less than a word to do */
	if (len & 3) {
		buf += len & ~3;

		for (; len & 3; len--)
			*buf++ = readb(info->regs + S3C2440_NFDATA);
	}
}

static void s3c2410_nand_write_buf(struct nand_chip *this, const u_char *buf,
				   int len)
{
	writesb(this->legacy.IO_ADDR_W, buf, len);
}

static void s3c2440_nand_write_buf(struct nand_chip *this, const u_char *buf,
				   int len)
{
	struct mtd_info *mtd = nand_to_mtd(this);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);

	writesl(info->regs + S3C2440_NFDATA, buf, len >> 2);

	/* cleanup any fractional write */
	if (len & 3) {
		buf += len & ~3;

		for (; len & 3; len--, buf++)
			writeb(*buf, info->regs + S3C2440_NFDATA);
	}
}

/* cpufreq driver support */

#ifdef CONFIG_ARM_S3C24XX_CPUFREQ

static int s3c2410_nand_cpufreq_transition(struct notifier_block *nb,
					  unsigned long val, void *data)
{
	struct s3c2410_nand_info *info;
	unsigned long newclk;

	info = container_of(nb, struct s3c2410_nand_info, freq_transition);
	newclk = clk_get_rate(info->clk);

	if ((val == CPUFREQ_POSTCHANGE && newclk < info->clk_rate) ||
	    (val == CPUFREQ_PRECHANGE && newclk > info->clk_rate)) {
		s3c2410_nand_setrate(info);
	}

	return 0;
}

static inline int s3c2410_nand_cpufreq_register(struct s3c2410_nand_info *info)
{
	info->freq_transition.notifier_call = s3c2410_nand_cpufreq_transition;

	return cpufreq_register_notifier(&info->freq_transition,
					 CPUFREQ_TRANSITION_NOTIFIER);
}

static inline void
s3c2410_nand_cpufreq_deregister(struct s3c2410_nand_info *info)
{
	cpufreq_unregister_notifier(&info->freq_transition,
				    CPUFREQ_TRANSITION_NOTIFIER);
}

#else
static inline int s3c2410_nand_cpufreq_register(struct s3c2410_nand_info *info)
{
	return 0;
}

static inline void
s3c2410_nand_cpufreq_deregister(struct s3c2410_nand_info *info)
{
}
#endif

/* device management functions */

static int s3c24xx_nand_remove(struct platform_device *pdev)
{
	struct s3c2410_nand_info *info = to_nand_info(pdev);

	if (info == NULL)
		return 0;

	s3c2410_nand_cpufreq_deregister(info);

	/* Release all our mtds  and their partitions, then go through
	 * freeing the resources used
	 */

	if (info->mtds != NULL) {
		struct s3c2410_nand_mtd *ptr = info->mtds;
		int mtdno;

		for (mtdno = 0; mtdno < info->mtd_count; mtdno++, ptr++) {
			pr_debug("releasing mtd %d (%p)\n", mtdno, ptr);
			nand_release(&ptr->chip);
		}
	}

	/* free the common resources */

	if (!IS_ERR(info->clk))
		s3c2410_nand_clk_set_state(info, CLOCK_DISABLE);

	return 0;
}

static int s3c2410_nand_add_partition(struct s3c2410_nand_info *info,
				      struct s3c2410_nand_mtd *mtd,
				      struct s3c2410_nand_set *set)
{
	if (set) {
		struct mtd_info *mtdinfo = nand_to_mtd(&mtd->chip);

		mtdinfo->name = set->name;

		return mtd_device_register(mtdinfo, set->partitions,
					   set->nr_partitions);
	}

	return -ENODEV;
}

static int s3c2410_nand_setup_data_interface(struct nand_chip *chip, int csline,
					const struct nand_data_interface *conf)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	struct s3c2410_platform_nand *pdata = info->platform;
	const struct nand_sdr_timings *timings;
	int tacls;

	timings = nand_get_sdr_timings(conf);
	if (IS_ERR(timings))
		return -ENOTSUPP;

	tacls = timings->tCLS_min - timings->tWP_min;
	if (tacls < 0)
		tacls = 0;

	pdata->tacls  = DIV_ROUND_UP(tacls, 1000);
	pdata->twrph0 = DIV_ROUND_UP(timings->tWP_min, 1000);
	pdata->twrph1 = DIV_ROUND_UP(timings->tCLH_min, 1000);

	return s3c2410_nand_setrate(info);
}

/**
 * s3c2410_nand_init_chip - initialise a single instance of an chip
 * @info: The base NAND controller the chip is on.
 * @nmtd: The new controller MTD instance to fill in.
 * @set: The information passed from the board specific platform data.
 *
 * Initialise the given @nmtd from the information in @info and @set. This
 * readies the structure for use with the MTD layer functions by ensuring
 * all pointers are setup and the necessary control routines selected.
 */
static void s3c2410_nand_init_chip(struct s3c2410_nand_info *info,
				   struct s3c2410_nand_mtd *nmtd,
				   struct s3c2410_nand_set *set)
{
	struct device_node *np = info->device->of_node;
	struct nand_chip *chip = &nmtd->chip;
	void __iomem *regs = info->regs;

	nand_set_flash_node(chip, set->of_node);

	chip->legacy.write_buf    = s3c2410_nand_write_buf;
	chip->legacy.read_buf     = s3c2410_nand_read_buf;
	chip->select_chip  = s3c2410_nand_select_chip;
	chip->legacy.chip_delay   = 50;
	nand_set_controller_data(chip, nmtd);
	chip->options	   = set->options;
	chip->controller   = &info->controller;

	/*
	 * let's keep behavior unchanged for legacy boards booting via pdata and
	 * auto-detect timings only when booting with a device tree.
	 */
	if (np)
		chip->setup_data_interface = s3c2410_nand_setup_data_interface;

	switch (info->cpu_type) {
	case TYPE_S3C2410:
		chip->legacy.IO_ADDR_W = regs + S3C2410_NFDATA;
		info->sel_reg   = regs + S3C2410_NFCONF;
		info->sel_bit	= S3C2410_NFCONF_nFCE;
		chip->legacy.cmd_ctrl  = s3c2410_nand_hwcontrol;
		chip->legacy.dev_ready = s3c2410_nand_devready;
		break;

	case TYPE_S3C2440:
		chip->legacy.IO_ADDR_W = regs + S3C2440_NFDATA;
		info->sel_reg   = regs + S3C2440_NFCONT;
		info->sel_bit	= S3C2440_NFCONT_nFCE;
		chip->legacy.cmd_ctrl  = s3c2440_nand_hwcontrol;
		chip->legacy.dev_ready = s3c2440_nand_devready;
		chip->legacy.read_buf  = s3c2440_nand_read_buf;
		chip->legacy.write_buf	= s3c2440_nand_write_buf;
		break;

	case TYPE_S3C2412:
		chip->legacy.IO_ADDR_W = regs + S3C2440_NFDATA;
		info->sel_reg   = regs + S3C2440_NFCONT;
		info->sel_bit	= S3C2412_NFCONT_nFCE0;
		chip->legacy.cmd_ctrl  = s3c2440_nand_hwcontrol;
		chip->legacy.dev_ready = s3c2412_nand_devready;

		if (readl(regs + S3C2410_NFCONF) & S3C2412_NFCONF_NANDBOOT)
			dev_info(info->device, "System booted from NAND\n");

		break;
	}

	chip->legacy.IO_ADDR_R = chip->legacy.IO_ADDR_W;

	nmtd->info	   = info;
	nmtd->set	   = set;

	chip->ecc.mode = info->platform->ecc_mode;

	/*
	 * If you use u-boot BBT creation code, specifying this flag will
	 * let the kernel fish out the BBT from the NAND.
	 */
	if (set->flash_bbt)
		chip->bbt_options |= NAND_BBT_USE_FLASH;
}

/**
 * s3c2410_nand_attach_chip - Init the ECC engine after NAND scan
 * @chip: The NAND chip
 *
 * This hook is called by the core after the identification of the NAND chip,
 * once the relevant per-chip information is up to date.. This call ensure that
 * we update the internal state accordingly.
 *
 * The internal state is currently limited to the ECC state information.
*/
static int s3c2410_nand_attach_chip(struct nand_chip *chip)
{
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);

	switch (chip->ecc.mode) {

	case NAND_ECC_NONE:
		dev_info(info->device, "ECC disabled\n");
		break;

	case NAND_ECC_SOFT:
		/*
		 * This driver expects Hamming based ECC when ecc_mode is set
		 * to NAND_ECC_SOFT. Force ecc.algo to NAND_ECC_HAMMING to
		 * avoid adding an extra ecc_algo field to
		 * s3c2410_platform_nand.
		 */
		chip->ecc.algo = NAND_ECC_HAMMING;
		dev_info(info->device, "soft ECC\n");
		break;

	case NAND_ECC_HW:
		chip->ecc.calculate = s3c2410_nand_calculate_ecc;
		chip->ecc.correct   = s3c2410_nand_correct_data;
		chip->ecc.strength  = 1;

		switch (info->cpu_type) {
		case TYPE_S3C2410:
			chip->ecc.hwctl	    = s3c2410_nand_enable_hwecc;
			chip->ecc.calculate = s3c2410_nand_calculate_ecc;
			break;

		case TYPE_S3C2412:
			chip->ecc.hwctl     = s3c2412_nand_enable_hwecc;
			chip->ecc.calculate = s3c2412_nand_calculate_ecc;
			break;

		case TYPE_S3C2440:
			chip->ecc.hwctl     = s3c2440_nand_enable_hwecc;
			chip->ecc.calculate = s3c2440_nand_calculate_ecc;
			break;
		}

		dev_dbg(info->device, "chip %p => page shift %d\n",
			chip, chip->page_shift);

		/* change the behaviour depending on whether we are using
		 * the large or small page nand device */
		if (chip->page_shift > 10) {
			chip->ecc.size	    = 256;
			chip->ecc.bytes	    = 3;
		} else {
			chip->ecc.size	    = 512;
			chip->ecc.bytes	    = 3;
			mtd_set_ooblayout(nand_to_mtd(chip),
					  &s3c2410_ooblayout_ops);
		}

		dev_info(info->device, "hardware ECC\n");
		break;

	default:
		dev_err(info->device, "invalid ECC mode!\n");
		return -EINVAL;
	}

	if (chip->bbt_options & NAND_BBT_USE_FLASH)
		chip->options |= NAND_SKIP_BBTSCAN;

	return 0;
}

static const struct nand_controller_ops s3c24xx_nand_controller_ops = {
	.attach_chip = s3c2410_nand_attach_chip,
};

static const struct of_device_id s3c24xx_nand_dt_ids[] = {
	{
		.compatible = "samsung,s3c2410-nand",
		.data = &s3c2410_nand_devtype_data,
	}, {
		/* also compatible with s3c6400 */
		.compatible = "samsung,s3c2412-nand",
		.data = &s3c2412_nand_devtype_data,
	}, {
		.compatible = "samsung,s3c2440-nand",
		.data = &s3c2440_nand_devtype_data,
	},
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, s3c24xx_nand_dt_ids);

static int s3c24xx_nand_probe_dt(struct platform_device *pdev)
{
	const struct s3c24XX_nand_devtype_data *devtype_data;
	struct s3c2410_platform_nand *pdata;
	struct s3c2410_nand_info *info = platform_get_drvdata(pdev);
	struct device_node *np = pdev->dev.of_node, *child;
	struct s3c2410_nand_set *sets;

	devtype_data = of_device_get_match_data(&pdev->dev);
	if (!devtype_data)
		return -ENODEV;

	info->cpu_type = devtype_data->type;

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

	pdev->dev.platform_data = pdata;

	pdata->nr_sets = of_get_child_count(np);
	if (!pdata->nr_sets)
		return 0;

	sets = devm_kcalloc(&pdev->dev, pdata->nr_sets, sizeof(*sets),
			    GFP_KERNEL);
	if (!sets)
		return -ENOMEM;

	pdata->sets = sets;

	for_each_available_child_of_node(np, child) {
		sets->name = (char *)child->name;
		sets->of_node = child;
		sets->nr_chips = 1;

		of_node_get(child);

		sets++;
	}

	return 0;
}

static int s3c24xx_nand_probe_pdata(struct platform_device *pdev)
{
	struct s3c2410_nand_info *info = platform_get_drvdata(pdev);

	info->cpu_type = platform_get_device_id(pdev)->driver_data;

	return 0;
}

/* s3c24xx_nand_probe
 *
 * called by device layer when it finds a device matching
 * one our driver can handled. This code checks to see if
 * it can allocate all necessary resources then calls the
 * nand layer to look for devices
*/
static int s3c24xx_nand_probe(struct platform_device *pdev)
{
	struct s3c2410_platform_nand *plat;
	struct s3c2410_nand_info *info;
	struct s3c2410_nand_mtd *nmtd;
	struct s3c2410_nand_set *sets;
	struct resource *res;
	int err = 0;
	int size;
	int nr_sets;
	int setno;

	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
	if (info == NULL) {
		err = -ENOMEM;
		goto exit_error;
	}

	platform_set_drvdata(pdev, info);

	nand_controller_init(&info->controller);
	info->controller.ops = &s3c24xx_nand_controller_ops;

	/* get the clock source and enable it */

	info->clk = devm_clk_get(&pdev->dev, "nand");
	if (IS_ERR(info->clk)) {
		dev_err(&pdev->dev, "failed to get clock\n");
		err = -ENOENT;
		goto exit_error;
	}

	s3c2410_nand_clk_set_state(info, CLOCK_ENABLE);

	if (pdev->dev.of_node)
		err = s3c24xx_nand_probe_dt(pdev);
	else
		err = s3c24xx_nand_probe_pdata(pdev);

	if (err)
		goto exit_error;

	plat = to_nand_plat(pdev);

	/* allocate and map the resource */

	/* currently we assume we have the one resource */
	res = pdev->resource;
	size = resource_size(res);

	info->device	= &pdev->dev;
	info->platform	= plat;

	info->regs = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(info->regs)) {
		err = PTR_ERR(info->regs);
		goto exit_error;
	}

	dev_dbg(&pdev->dev, "mapped registers at %p\n", info->regs);

	if (!plat->sets || plat->nr_sets < 1) {
		err = -EINVAL;
		goto exit_error;
	}

	sets = plat->sets;
	nr_sets = plat->nr_sets;

	info->mtd_count = nr_sets;

	/* allocate our information */

	size = nr_sets * sizeof(*info->mtds);
	info->mtds = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
	if (info->mtds == NULL) {
		err = -ENOMEM;
		goto exit_error;
	}

	/* initialise all possible chips */

	nmtd = info->mtds;

	for (setno = 0; setno < nr_sets; setno++, nmtd++, sets++) {
		struct mtd_info *mtd = nand_to_mtd(&nmtd->chip);

		pr_debug("initialising set %d (%p, info %p)\n",
			 setno, nmtd, info);

		mtd->dev.parent = &pdev->dev;
		s3c2410_nand_init_chip(info, nmtd, sets);

		err = nand_scan(&nmtd->chip, sets ? sets->nr_chips : 1);
		if (err)
			goto exit_error;

		s3c2410_nand_add_partition(info, nmtd, sets);
	}

	/* initialise the hardware */
	err = s3c2410_nand_inithw(info);
	if (err != 0)
		goto exit_error;

	err = s3c2410_nand_cpufreq_register(info);
	if (err < 0) {
		dev_err(&pdev->dev, "failed to init cpufreq support\n");
		goto exit_error;
	}

	if (allow_clk_suspend(info)) {
		dev_info(&pdev->dev, "clock idle support enabled\n");
		s3c2410_nand_clk_set_state(info, CLOCK_SUSPEND);
	}

	return 0;

 exit_error:
	s3c24xx_nand_remove(pdev);

	if (err == 0)
		err = -EINVAL;
	return err;
}

/* PM Support */
#ifdef CONFIG_PM

static int s3c24xx_nand_suspend(struct platform_device *dev, pm_message_t pm)
{
	struct s3c2410_nand_info *info = platform_get_drvdata(dev);

	if (info) {
		info->save_sel = readl(info->sel_reg);

		/* For the moment, we must ensure nFCE is high during
		 * the time we are suspended. This really should be
		 * handled by suspending the MTDs we are using, but
		 * that is currently not the case. */

		writel(info->save_sel | info->sel_bit, info->sel_reg);

		s3c2410_nand_clk_set_state(info, CLOCK_DISABLE);
	}

	return 0;
}

static int s3c24xx_nand_resume(struct platform_device *dev)
{
	struct s3c2410_nand_info *info = platform_get_drvdata(dev);
	unsigned long sel;

	if (info) {
		s3c2410_nand_clk_set_state(info, CLOCK_ENABLE);
		s3c2410_nand_inithw(info);

		/* Restore the state of the nFCE line. */

		sel = readl(info->sel_reg);
		sel &= ~info->sel_bit;
		sel |= info->save_sel & info->sel_bit;
		writel(sel, info->sel_reg);

		s3c2410_nand_clk_set_state(info, CLOCK_SUSPEND);
	}

	return 0;
}

#else
#define s3c24xx_nand_suspend NULL
#define s3c24xx_nand_resume NULL
#endif

/* driver device registration */

static const struct platform_device_id s3c24xx_driver_ids[] = {
	{
		.name		= "s3c2410-nand",
		.driver_data	= TYPE_S3C2410,
	}, {
		.name		= "s3c2440-nand",
		.driver_data	= TYPE_S3C2440,
	}, {
		.name		= "s3c2412-nand",
		.driver_data	= TYPE_S3C2412,
	}, {
		.name		= "s3c6400-nand",
		.driver_data	= TYPE_S3C2412, /* compatible with 2412 */
	},
	{ }
};

MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);

static struct platform_driver s3c24xx_nand_driver = {
	.probe		= s3c24xx_nand_probe,
	.remove		= s3c24xx_nand_remove,
	.suspend	= s3c24xx_nand_suspend,
	.resume		= s3c24xx_nand_resume,
	.id_table	= s3c24xx_driver_ids,
	.driver		= {
		.name	= "s3c24xx-nand",
		.of_match_table = s3c24xx_nand_dt_ids,
	},
};

module_platform_driver(s3c24xx_nand_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_DESCRIPTION("S3C24XX MTD NAND driver");