/* linux/drivers/mtd/nand/s3c2410.c
   *
   * 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/init.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/mtd/mtd.h>
  #include <linux/mtd/nand.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 struct nand_ecclayout nand_hw_eccoob = {
  	.eccbytes = 3,
  	.eccpos = {0, 1, 2},
  	.oobfree = {{8, 8}}
  };
  
  /* 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.
   * @scan_res: The result from calling nand_scan_ident().
  */
  struct s3c2410_nand_mtd {
  	struct mtd_info			mtd;
  	struct nand_chip		chip;
  	struct s3c2410_nand_set		*set;
  	struct s3c2410_nand_info	*info;
  	int				scan_res;
  };
  
  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_hw_control		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_CPU_FREQ
  	struct notifier_block	freq_transition;
  #endif
  };
  
  /* conversion functions */
  
  static struct s3c2410_nand_mtd *s3c2410_nand_mtd_toours(struct mtd_info *mtd)
  {
  	return container_of(mtd, struct s3c2410_nand_mtd, mtd);
  }
  
  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(info->clk);
  	} else {
  		if (new_state == CLOCK_ENABLE)
  			clk_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
  ", result, clk, wanted);
  
  	if (result > max) {
  		pr_err("%d ns is too big for current clock rate %ld
  ",
  			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
  ");
  		return -EINVAL;
  	}
  
  	dev_info(info->device, "Tacls=%d, %dns Twrph0=%d %dns, Twrph1=%d %dns
  ",
  		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
  ", 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
   * @mtd: The MTD instance for this chip.
   * @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 mtd_info *mtd, int chip)
  {
  	struct s3c2410_nand_info *info;
  	struct s3c2410_nand_mtd *nmtd;
  	struct nand_chip *this = mtd->priv;
  	unsigned long cur;
  
  	nmtd = this->priv;
  	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
  ", 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 mtd_info *mtd, int cmd,
  				   unsigned int ctrl)
  {
  	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 mtd_info *mtd, int cmd,
  				   unsigned int ctrl)
  {
  	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 mtd_info *mtd)
  {
  	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 mtd_info *mtd)
  {
  	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 mtd_info *mtd)
  {
  	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
  	return readb(info->regs + S3C2412_NFSTAT) & S3C2412_NFSTAT_READY;
  }
  
  /* ECC handling functions */
  
  #ifdef CONFIG_MTD_NAND_S3C2410_HWECC
  static int s3c2410_nand_correct_data(struct mtd_info *mtd, u_char *dat,
  				     u_char *read_ecc, u_char *calc_ecc)
  {
  	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)
  ", __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
  ",
  		 __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
  ",
  			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);
  
  	if ((diff0 & ~(1<<fls(diff0))) == 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 mtd_info *mtd, int mode)
  {
  	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
  	unsigned long ctrl;
  
  	ctrl = readl(info->regs + S3C2410_NFCONF);
  	ctrl |= S3C2410_NFCONF_INITECC;
  	writel(ctrl, info->regs + S3C2410_NFCONF);
  }
  
  static void s3c2412_nand_enable_hwecc(struct mtd_info *mtd, int mode)
  {
  	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
  	unsigned long ctrl;
  
  	ctrl = readl(info->regs + S3C2440_NFCONT);
  	writel(ctrl | S3C2412_NFCONT_INIT_MAIN_ECC,
  	       info->regs + S3C2440_NFCONT);
  }
  
  static void s3c2440_nand_enable_hwecc(struct mtd_info *mtd, int mode)
  {
  	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
  	unsigned long ctrl;
  
  	ctrl = readl(info->regs + S3C2440_NFCONT);
  	writel(ctrl | S3C2440_NFCONT_INITECC, info->regs + S3C2440_NFCONT);
  }
  
  static int s3c2410_nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
  				      u_char *ecc_code)
  {
  	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
  ", __func__, 3, ecc_code);
  
  	return 0;
  }
  
  static int s3c2412_nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
  				      u_char *ecc_code)
  {
  	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
  ", __func__, 3, ecc_code);
  
  	return 0;
  }
  
  static int s3c2440_nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
  				      u_char *ecc_code)
  {
  	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
  ", __func__, ecc & 0xffffff);
  
  	return 0;
  }
  #endif
  
  /* 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 mtd_info *mtd, u_char *buf, int len)
  {
  	struct nand_chip *this = mtd->priv;
  	readsb(this->IO_ADDR_R, buf, len);
  }
  
  static void s3c2440_nand_read_buf(struct mtd_info *mtd, u_char *buf, int len)
  {
  	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 mtd_info *mtd, const u_char *buf,
  				   int len)
  {
  	struct nand_chip *this = mtd->priv;
  	writesb(this->IO_ADDR_W, buf, len);
  }
  
  static void s3c2440_nand_write_buf(struct mtd_info *mtd, const u_char *buf,
  				   int len)
  {
  	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_CPU_FREQ
  
  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)
  ", mtdno, ptr);
  			nand_release(&ptr->mtd);
  		}
  	}
  
  	/* 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) {
  		mtd->mtd.name = set->name;
  
  		return mtd_device_parse_register(&mtd->mtd, NULL, NULL,
  					 set->partitions, set->nr_partitions);
  	}
  
  	return -ENODEV;
  }
  
  /**
   * 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 nand_chip *chip = &nmtd->chip;
  	void __iomem *regs = info->regs;
  
  	chip->write_buf    = s3c2410_nand_write_buf;
  	chip->read_buf     = s3c2410_nand_read_buf;
  	chip->select_chip  = s3c2410_nand_select_chip;
  	chip->chip_delay   = 50;
  	chip->priv	   = nmtd;
  	chip->options	   = set->options;
  	chip->controller   = &info->controller;
  
  	switch (info->cpu_type) {
  	case TYPE_S3C2410:
  		chip->IO_ADDR_W = regs + S3C2410_NFDATA;
  		info->sel_reg   = regs + S3C2410_NFCONF;
  		info->sel_bit	= S3C2410_NFCONF_nFCE;
  		chip->cmd_ctrl  = s3c2410_nand_hwcontrol;
  		chip->dev_ready = s3c2410_nand_devready;
  		break;
  
  	case TYPE_S3C2440:
  		chip->IO_ADDR_W = regs + S3C2440_NFDATA;
  		info->sel_reg   = regs + S3C2440_NFCONT;
  		info->sel_bit	= S3C2440_NFCONT_nFCE;
  		chip->cmd_ctrl  = s3c2440_nand_hwcontrol;
  		chip->dev_ready = s3c2440_nand_devready;
  		chip->read_buf  = s3c2440_nand_read_buf;
  		chip->write_buf	= s3c2440_nand_write_buf;
  		break;
  
  	case TYPE_S3C2412:
  		chip->IO_ADDR_W = regs + S3C2440_NFDATA;
  		info->sel_reg   = regs + S3C2440_NFCONT;
  		info->sel_bit	= S3C2412_NFCONT_nFCE0;
  		chip->cmd_ctrl  = s3c2440_nand_hwcontrol;
  		chip->dev_ready = s3c2412_nand_devready;
  
  		if (readl(regs + S3C2410_NFCONF) & S3C2412_NFCONF_NANDBOOT)
  			dev_info(info->device, "System booted from NAND
  ");
  
  		break;
  	}
  
  	chip->IO_ADDR_R = chip->IO_ADDR_W;
  
  	nmtd->info	   = info;
  	nmtd->mtd.priv	   = chip;
  	nmtd->mtd.owner    = THIS_MODULE;
  	nmtd->set	   = set;
  
  #ifdef CONFIG_MTD_NAND_S3C2410_HWECC
  	chip->ecc.calculate = s3c2410_nand_calculate_ecc;
  	chip->ecc.correct   = s3c2410_nand_correct_data;
  	chip->ecc.mode	    = NAND_ECC_HW;
  	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;
  	}
  #else
  	chip->ecc.mode	    = NAND_ECC_SOFT;
  #endif
  
  	if (set->ecc_layout != NULL)
  		chip->ecc.layout = set->ecc_layout;
  
  	if (set->disable_ecc)
  		chip->ecc.mode	= NAND_ECC_NONE;
  
  	switch (chip->ecc.mode) {
  	case NAND_ECC_NONE:
  		dev_info(info->device, "NAND ECC disabled
  ");
  		break;
  	case NAND_ECC_SOFT:
  		dev_info(info->device, "NAND soft ECC
  ");
  		break;
  	case NAND_ECC_HW:
  		dev_info(info->device, "NAND hardware ECC
  ");
  		break;
  	default:
  		dev_info(info->device, "NAND ECC UNKNOWN
  ");
  		break;
  	}
  
  	/* If you use u-boot BBT creation code, specifying this flag will
  	 * let the kernel fish out the BBT from the NAND, and also skip the
  	 * full NAND scan that can take 1/2s or so. Little things... */
  	if (set->flash_bbt) {
  		chip->bbt_options |= NAND_BBT_USE_FLASH;
  		chip->options |= NAND_SKIP_BBTSCAN;
  	}
  }
  
  /**
   * s3c2410_nand_update_chip - post probe update
   * @info: The controller instance.
   * @nmtd: The driver version of the MTD instance.
   *
   * This routine is called after the chip probe has successfully completed
   * and the relevant per-chip information updated. This call ensure that
   * we update the internal state accordingly.
   *
   * The internal state is currently limited to the ECC state information.
  */
  static void s3c2410_nand_update_chip(struct s3c2410_nand_info *info,
  				     struct s3c2410_nand_mtd *nmtd)
  {
  	struct nand_chip *chip = &nmtd->chip;
  
  	dev_dbg(info->device, "chip %p => page shift %d
  ",
  		chip, chip->page_shift);
  
  	if (chip->ecc.mode != NAND_ECC_HW)
  		return;
  
  		/* 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;
  		chip->ecc.layout    = &nand_hw_eccoob;
  	}
  }
  
  /* 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 = to_nand_plat(pdev);
  	enum s3c_cpu_type cpu_type;
  	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;
  
  	cpu_type = platform_get_device_id(pdev)->driver_data;
  
  	pr_debug("s3c2410_nand_probe(%p)
  ", pdev);
  
  	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
  	if (info == NULL) {
  		err = -ENOMEM;
  		goto exit_error;
  	}
  
  	platform_set_drvdata(pdev, info);
  
  	spin_lock_init(&info->controller.lock);
  	init_waitqueue_head(&info->controller.wq);
  
  	/* 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
  ");
  		err = -ENOENT;
  		goto exit_error;
  	}
  
  	s3c2410_nand_clk_set_state(info, CLOCK_ENABLE);
  
  	/* 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->cpu_type	= cpu_type;
  
  	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
  ", info->regs);
  
  	/* initialise the hardware */
  
  	err = s3c2410_nand_inithw(info);
  	if (err != 0)
  		goto exit_error;
  
  	sets = (plat != NULL) ? plat->sets : NULL;
  	nr_sets = (plat != NULL) ? plat->nr_sets : 1;
  
  	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++) {
  		pr_debug("initialising set %d (%p, info %p)
  ",
  			 setno, nmtd, info);
  
  		s3c2410_nand_init_chip(info, nmtd, sets);
  
  		nmtd->scan_res = nand_scan_ident(&nmtd->mtd,
  						 (sets) ? sets->nr_chips : 1,
  						 NULL);
  
  		if (nmtd->scan_res == 0) {
  			s3c2410_nand_update_chip(info, nmtd);
  			nand_scan_tail(&nmtd->mtd);
  			s3c2410_nand_add_partition(info, nmtd, sets);
  		}
  
  		if (sets != NULL)
  			sets++;
  	}
  
  	err = s3c2410_nand_cpufreq_register(info);
  	if (err < 0) {
  		dev_err(&pdev->dev, "failed to init cpufreq support
  ");
  		goto exit_error;
  	}
  
  	if (allow_clk_suspend(info)) {
  		dev_info(&pdev->dev, "clock idle support enabled
  ");
  		s3c2410_nand_clk_set_state(info, CLOCK_SUSPEND);
  	}
  
  	pr_debug("initialised ok
  ");
  	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 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",
  		.owner	= THIS_MODULE,
  	},
  };
  
  module_platform_driver(s3c24xx_nand_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
  MODULE_DESCRIPTION("S3C24XX MTD NAND driver");