x86/mm/pat: Don't report PAT on CPUs that don't support it

[linux/fpc-iii.git] / drivers / mtd / nand / s3c2410.c

/* 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/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/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 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.
 * @scan_res: The result from calling nand_scan_ident().
*/
struct s3c2410_nand_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_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
 * @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_to_nand(mtd);
        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 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 */

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)\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 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\n", __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\n", __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\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 mtd_info *mtd, u_char *buf, int len)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        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_to_nand(mtd);
        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_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(nand_to_mtd(&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_parse_register(mtdinfo, NULL, NULL,
                                         set->partitions, set->nr_partitions);
        }

        return -ENODEV;
}

static int s3c2410_nand_setup_data_interface(struct mtd_info *mtd,
                                        const struct nand_data_interface *conf,
                                        bool check_only)
{
        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->write_buf    = s3c2410_nand_write_buf;
        chip->read_buf     = s3c2410_nand_read_buf;
        chip->select_chip  = s3c2410_nand_select_chip;
        chip->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->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\n");

                break;
        }

        chip->IO_ADDR_R = chip->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_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 int s3c2410_nand_update_chip(struct s3c2410_nand_info *info,
                                    struct s3c2410_nand_mtd *nmtd)
{
        struct nand_chip *chip = &nmtd->chip;

        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 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_kzalloc(&pdev->dev, sizeof(*sets) * pdata->nr_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_hw_control_init(&info->controller);

        /* 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);

        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++) {
                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);

                nmtd->scan_res = nand_scan_ident(mtd,
                                                 (sets) ? sets->nr_chips : 1,
                                                 NULL);

                if (nmtd->scan_res == 0) {
                        err = s3c2410_nand_update_chip(info, nmtd);
                        if (err < 0)
                                goto exit_error;
                        nand_scan_tail(mtd);
                        s3c2410_nand_add_partition(info, nmtd, sets);
                }

                if (sets != NULL)
                        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");