/* linux/drivers/mtd/nand/s3c2410.c
 *
 * Copyright (c) 2004,2005 Simtec Electronics
 *	http://www.simtec.co.uk/products/SWLINUX/
 *	Ben Dooks <ben@simtec.co.uk>
 *
 * Samsung S3C2410/S3C240 NAND driver
 *
 * Changelog:
 *	21-Sep-2004  BJD  Initial version
 *	23-Sep-2004  BJD  Mulitple device support
 *	28-Sep-2004  BJD  Fixed ECC placement for Hardware mode
 *	12-Oct-2004  BJD  Fixed errors in use of platform data
 *	18-Feb-2005  BJD  Fix sparse errors
 *	14-Mar-2005  BJD  Applied tglx's code reduction patch
 *	02-May-2005  BJD  Fixed s3c2440 support
 *	02-May-2005  BJD  Reduced hwcontrol decode
 *	20-Jun-2005  BJD  Updated s3c2440 support, fixed timing bug
 *	08-Jul-2005  BJD  Fix OOPS when no platform data supplied
 *	20-Oct-2005  BJD  Fix timing calculation bug
 *	14-Jan-2006  BJD  Allow clock to be stopped when idle
 *
 * $Id: s3c2410.c,v 1.23 2006/04/01 18:06:29 bjd Exp $
 *
 * 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
*/

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

#include <asm/io.h>

#include <asm/arch/regs-nand.h>
#include <asm/arch/nand.h>

#define PFX "s3c2410-nand: "

#ifdef CONFIG_MTD_NAND_S3C2410_HWECC
static int hardware_ecc = 1;
#else
static int hardware_ecc = 0;
#endif

#ifdef CONFIG_MTD_NAND_S3C2410_CLKSTOP
static int clock_stop = 1;
#else
static const int clock_stop = 0;
#endif


/* 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 {
	struct mtd_info			mtd;
	struct nand_chip		chip;
	struct s3c2410_nand_set		*set;
	struct s3c2410_nand_info	*info;
	int				scan_res;
};

/* overview of the s3c2410 nand state */

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 resource			*area;
	struct clk			*clk;
	void __iomem			*regs;
	int				mtd_count;

	unsigned char			is_s3c2440;
};

/* 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->dev.platform_data;
}

static inline int allow_clk_stop(struct s3c2410_nand_info *info)
{
	return clock_stop;
}

/* timing calculations */

#define NS_IN_KHZ 1000000

static int s3c2410_nand_calc_rate(int wanted, unsigned long clk, int max)
{
	int result;

	result = (wanted * clk) / NS_IN_KHZ;
	result++;

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

	if (result > max) {
		printk("%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 */

static int s3c2410_nand_inithw(struct s3c2410_nand_info *info, struct platform_device *pdev)
{
	struct s3c2410_platform_nand *plat = to_nand_plat(pdev);
	unsigned long clkrate = clk_get_rate(info->clk);
	int tacls, twrph0, twrph1;
	unsigned long cfg;

	/* calculate the timing information for the controller */

	clkrate /= 1000;	/* turn clock into kHz for ease of use */

	if (plat != NULL) {
		tacls = s3c2410_nand_calc_rate(plat->tacls, clkrate, 4);
		twrph0 = s3c2410_nand_calc_rate(plat->twrph0, clkrate, 8);
		twrph1 = s3c2410_nand_calc_rate(plat->twrph1, clkrate, 8);
	} else {
		/* default timings */
		tacls = 4;
		twrph0 = 8;
		twrph1 = 8;
	}

	if (tacls < 0 || twrph0 < 0 || twrph1 < 0) {
		printk(KERN_ERR PFX "cannot get timings suitable for board\n");
		return -EINVAL;
	}

	printk(KERN_INFO PFX "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));

	if (!info->is_s3c2440) {
		cfg = S3C2410_NFCONF_EN;
		cfg |= S3C2410_NFCONF_TACLS(tacls - 1);
		cfg |= S3C2410_NFCONF_TWRPH0(twrph0 - 1);
		cfg |= S3C2410_NFCONF_TWRPH1(twrph1 - 1);
	} else {
		cfg = S3C2440_NFCONF_TACLS(tacls - 1);
		cfg |= S3C2440_NFCONF_TWRPH0(twrph0 - 1);
		cfg |= S3C2440_NFCONF_TWRPH1(twrph1 - 1);

		/* enable the controller and de-assert nFCE */

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

	pr_debug(PFX "NF_CONF is 0x%lx\n", cfg);

	writel(cfg, info->regs + S3C2410_NFCONF);
	return 0;
}

/* select 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;
	void __iomem *reg;
	unsigned long cur;
	unsigned long bit;

	nmtd = this->priv;
	info = nmtd->info;

	bit = (info->is_s3c2440) ? S3C2440_NFCONT_nFCE : S3C2410_NFCONF_nFCE;
	reg = info->regs + ((info->is_s3c2440) ? S3C2440_NFCONT : S3C2410_NFCONF);

	if (chip != -1 && allow_clk_stop(info))
		clk_enable(info->clk);

	cur = readl(reg);

	if (chip == -1) {
		cur |= bit;
	} else {
		if (nmtd->set != NULL && chip > nmtd->set->nr_chips) {
			printk(KERN_ERR PFX "chip %d out of range\n", chip);
			return;
		}

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

		cur &= ~bit;
	}

	writel(cur, reg);

	if (chip == -1 && allow_clk_stop(info))
		clk_disable(info->clk);
}

/* 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);

	if (info->is_s3c2440)
		return readb(info->regs + S3C2440_NFSTAT) & S3C2440_NFSTAT_READY;
	return readb(info->regs + S3C2410_NFSTAT) & S3C2410_NFSTAT_BUSY;
}

/* ECC handling functions */

static int s3c2410_nand_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc, u_char *calc_ecc)
{
	pr_debug("s3c2410_nand_correct_data(%p,%p,%p,%p)\n", mtd, dat, read_ecc, calc_ecc);

	pr_debug("eccs: read %02x,%02x,%02x vs calc %02x,%02x,%02x\n",
		 read_ecc[0], read_ecc[1], read_ecc[2], calc_ecc[0], calc_ecc[1], calc_ecc[2]);

	if (read_ecc[0] == calc_ecc[0] && read_ecc[1] == calc_ecc[1] && read_ecc[2] == calc_ecc[2])
		return 0;

	/* we curently have no method for correcting the error */

	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 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("calculate_ecc: returning ecc %02x,%02x,%02x\n", ecc_code[0], ecc_code[1], ecc_code[2]);

	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("calculate_ecc: returning ecc %02x,%02x,%02x\n", ecc_code[0], ecc_code[1], ecc_code[2]);

	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->priv;
	readsb(this->IO_ADDR_R, buf, len);
}

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);
}

/* device management functions */

static int s3c2410_nand_remove(struct platform_device *pdev)
{
	struct s3c2410_nand_info *info = to_nand_info(pdev);

	platform_set_drvdata(pdev, NULL);

	if (info == NULL)
		return 0;

	/* first thing we need to do is 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->mtd);
		}

		kfree(info->mtds);
	}

	/* free the common resources */

	if (info->clk != NULL && !IS_ERR(info->clk)) {
		if (!allow_clk_stop(info))
			clk_disable(info->clk);
		clk_put(info->clk);
	}

	if (info->regs != NULL) {
		iounmap(info->regs);
		info->regs = NULL;
	}

	if (info->area != NULL) {
		release_resource(info->area);
		kfree(info->area);
		info->area = NULL;
	}

	kfree(info);

	return 0;
}

#ifdef CONFIG_MTD_PARTITIONS
static int s3c2410_nand_add_partition(struct s3c2410_nand_info *info,
				      struct s3c2410_nand_mtd *mtd,
				      struct s3c2410_nand_set *set)
{
	if (set == NULL)
		return add_mtd_device(&mtd->mtd);

	if (set->nr_partitions > 0 && set->partitions != NULL) {
		return add_mtd_partitions(&mtd->mtd, set->partitions, set->nr_partitions);
	}

	return add_mtd_device(&mtd->mtd);
}
#else
static int s3c2410_nand_add_partition(struct s3c2410_nand_info *info,
				      struct s3c2410_nand_mtd *mtd,
				      struct s3c2410_nand_set *set)
{
	return add_mtd_device(&mtd->mtd);
}
#endif

/* s3c2410_nand_init_chip
 *
 * init a single instance of an chip
*/

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;

	chip->IO_ADDR_R	   = info->regs + S3C2410_NFDATA;
	chip->IO_ADDR_W    = info->regs + S3C2410_NFDATA;
	chip->cmd_ctrl     = s3c2410_nand_hwcontrol;
	chip->dev_ready    = s3c2410_nand_devready;
	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	   = 0;
	chip->controller   = &info->controller;

	if (info->is_s3c2440) {
		chip->IO_ADDR_R	 = info->regs + S3C2440_NFDATA;
		chip->IO_ADDR_W  = info->regs + S3C2440_NFDATA;
		chip->cmd_ctrl   = s3c2440_nand_hwcontrol;
	}

	nmtd->info	   = info;
	nmtd->mtd.priv	   = chip;
	nmtd->mtd.owner    = THIS_MODULE;
	nmtd->set	   = set;

	if (hardware_ecc) {
		chip->ecc.correct   = s3c2410_nand_correct_data;
		chip->ecc.hwctl	    = s3c2410_nand_enable_hwecc;
		chip->ecc.calculate = s3c2410_nand_calculate_ecc;
		chip->ecc.mode	    = NAND_ECC_HW;
		chip->ecc.size	    = 512;
		chip->ecc.bytes	    = 3;
		chip->ecc.layout    = &nand_hw_eccoob;

		if (info->is_s3c2440) {
			chip->ecc.hwctl     = s3c2440_nand_enable_hwecc;
			chip->ecc.calculate = s3c2440_nand_calculate_ecc;
		}
	} else {
		chip->ecc.mode	    = NAND_ECC_SOFT;
	}
}

/* s3c2410_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, int is_s3c2440)
{
	struct s3c2410_platform_nand *plat = to_nand_plat(pdev);
	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;

	pr_debug("s3c2410_nand_probe(%p)\n", pdev);

	info = kmalloc(sizeof(*info), GFP_KERNEL);
	if (info == NULL) {
		dev_err(&pdev->dev, "no memory for flash info\n");
		err = -ENOMEM;
		goto exit_error;
	}

	memzero(info, sizeof(*info));
	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 = clk_get(&pdev->dev, "nand");
	if (IS_ERR(info->clk)) {
		dev_err(&pdev->dev, "failed to get clock");
		err = -ENOENT;
		goto exit_error;
	}

	clk_enable(info->clk);

	/* allocate and map the resource */

	/* currently we assume we have the one resource */
	res  = pdev->resource;
	size = res->end - res->start + 1;

	info->area = request_mem_region(res->start, size, pdev->name);

	if (info->area == NULL) {
		dev_err(&pdev->dev, "cannot reserve register region\n");
		err = -ENOENT;
		goto exit_error;
	}

	info->device     = &pdev->dev;
	info->platform   = plat;
	info->regs       = ioremap(res->start, size);
	info->is_s3c2440 = is_s3c2440;

	if (info->regs == NULL) {
		dev_err(&pdev->dev, "cannot reserve register region\n");
		err = -EIO;
		goto exit_error;
	}

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

	/* initialise the hardware */

	err = s3c2410_nand_inithw(info, pdev);
	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 = kmalloc(size, GFP_KERNEL);
	if (info->mtds == NULL) {
		dev_err(&pdev->dev, "failed to allocate mtd storage\n");
		err = -ENOMEM;
		goto exit_error;
	}

	memzero(info->mtds, size);

	/* initialise all possible chips */

	nmtd = info->mtds;

	for (setno = 0; setno < nr_sets; setno++, nmtd++) {
		pr_debug("initialising set %d (%p, info %p)\n", setno, nmtd, info);

		s3c2410_nand_init_chip(info, nmtd, sets);

		nmtd->scan_res = nand_scan(&nmtd->mtd, (sets) ? sets->nr_chips : 1);

		if (nmtd->scan_res == 0) {
			s3c2410_nand_add_partition(info, nmtd, sets);
		}

		if (sets != NULL)
			sets++;
	}

	if (allow_clk_stop(info)) {
		dev_info(&pdev->dev, "clock idle support enabled\n");
		clk_disable(info->clk);
	}

	pr_debug("initialised ok\n");
	return 0;

 exit_error:
	s3c2410_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) {
		if (!allow_clk_stop(info))
			clk_disable(info->clk);
	}

	return 0;
}

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

	if (info) {
		clk_enable(info->clk);
		s3c2410_nand_inithw(info, dev);

		if (allow_clk_stop(info))
			clk_disable(info->clk);
	}

	return 0;
}

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

/* driver device registration */

static int s3c2410_nand_probe(struct platform_device *dev)
{
	return s3c24xx_nand_probe(dev, 0);
}

static int s3c2440_nand_probe(struct platform_device *dev)
{
	return s3c24xx_nand_probe(dev, 1);
}

static struct platform_driver s3c2410_nand_driver = {
	.probe		= s3c2410_nand_probe,
	.remove		= s3c2410_nand_remove,
	.suspend	= s3c24xx_nand_suspend,
	.resume		= s3c24xx_nand_resume,
	.driver		= {
		.name	= "s3c2410-nand",
		.owner	= THIS_MODULE,
	},
};

static struct platform_driver s3c2440_nand_driver = {
	.probe		= s3c2440_nand_probe,
	.remove		= s3c2410_nand_remove,
	.suspend	= s3c24xx_nand_suspend,
	.resume		= s3c24xx_nand_resume,
	.driver		= {
		.name	= "s3c2440-nand",
		.owner	= THIS_MODULE,
	},
};

static int __init s3c2410_nand_init(void)
{
	printk("S3C24XX NAND Driver, (c) 2004 Simtec Electronics\n");

	platform_driver_register(&s3c2440_nand_driver);
	return platform_driver_register(&s3c2410_nand_driver);
}

static void __exit s3c2410_nand_exit(void)
{
	platform_driver_unregister(&s3c2440_nand_driver);
	platform_driver_unregister(&s3c2410_nand_driver);
}

module_init(s3c2410_nand_init);
module_exit(s3c2410_nand_exit);

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