/* linux/drivers/mtd/nand/s3c2410.c
 *
 * Copyright (c) 2004 Simtec Electronics
 * Ben Dooks <ben@simtec.co.uk>
 *
 * Samsung S3C2410 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
 *
 * $Id: s3c2410.c,v 1.7 2005/01/05 18:05:14 dwmw2 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
*/

#include <config/mtd/nand/s3c2410/hwecc.h>
#include <config/mtd/nand/s3c2410/debug.h>

#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/device.h>
#include <linux/delay.h>
#include <linux/err.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/mach-types.h>
#include <asm/hardware/clock.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

/* new oob placement block for use with hardware ecc generation
 */

static struct nand_oobinfo nand_hw_eccoob = {
	.useecc = MTD_NANDECC_AUTOPLACE,
	.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				*regs;
	int				mtd_count;
};

/* 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 device *dev)
{
	return dev_get_drvdata(dev);
}

static struct s3c2410_platform_nand *to_nand_plat(struct device *dev)
{
	return dev->platform_data;
}

/* timing calculations */

#define NS_IN_KHZ 10000000

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

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

/* controller setup */

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

	/* calculate the timing information for the controller */

	if (plat != NULL) {
		tacls = s3c2410_nand_calc_rate(plat->tacls, clkrate, 8);
		twrph0 = s3c2410_nand_calc_rate(plat->twrph0, clkrate, 8);
		twrph1 = s3c2410_nand_calc_rate(plat->twrph1, clkrate, 8);
	} else {
		/* default timings */
		tacls = 8;
		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 "timing: Tacls %ldns, Twrph0 %ldns, Twrph1 %ldns\n",
	       to_ns(tacls, clkrate),
	       to_ns(twrph0, clkrate),
	       to_ns(twrph1, clkrate));

	cfg  = S3C2410_NFCONF_EN;
	cfg |= S3C2410_NFCONF_TACLS(tacls-1);
	cfg |= S3C2410_NFCONF_TWRPH0(twrph0-1);
	cfg |= S3C2410_NFCONF_TWRPH1(twrph1-1);

	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;
	unsigned long cur;

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

	cur = readl(info->regs + S3C2410_NFCONF);

	if (chip == -1) {
		cur |= S3C2410_NFCONF_nFCE;
	} else {
		if (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 &= ~S3C2410_NFCONF_nFCE;
	}

	writel(cur, info->regs + S3C2410_NFCONF);
}

/* command and control functions */

static void s3c2410_nand_hwcontrol(struct mtd_info *mtd, int cmd)
{
	struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	unsigned long cur;

	switch (cmd) {
	case NAND_CTL_SETNCE:
		cur = readl(info->regs + S3C2410_NFCONF);
		cur &= ~S3C2410_NFCONF_nFCE;
		writel(cur, info->regs + S3C2410_NFCONF);
		break;

	case NAND_CTL_CLRNCE:
		cur = readl(info->regs + S3C2410_NFCONF);
		cur |= S3C2410_NFCONF_nFCE;
		writel(cur, info->regs + S3C2410_NFCONF);
		break;

		/* we don't need to implement these */
	case NAND_CTL_SETCLE:
	case NAND_CTL_CLRCLE:
	case NAND_CTL_SETALE:
	case NAND_CTL_CLRALE:
		pr_debug(PFX "s3c2410_nand_hwcontrol(%d) unusedn", cmd);
		break;
	}
}

/* s3c2410_nand_command
 *
 * This function implements sending commands and the relevant address
 * information to the chip, via the hardware controller. Since the
 * S3C2410 generates the correct ALE/CLE signaling automatically, we
 * do not need to use hwcontrol.
*/

static void s3c2410_nand_command (struct mtd_info *mtd, unsigned command,
				  int column, int page_addr)
{
	register struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
	register struct nand_chip *this = mtd->priv;

	/*
	 * Write out the command to the device.
	 */
	if (command == NAND_CMD_SEQIN) {
		int readcmd;

		if (column >= mtd->oobblock) {
			/* OOB area */
			column -= mtd->oobblock;
			readcmd = NAND_CMD_READOOB;
		} else if (column < 256) {
			/* First 256 bytes --> READ0 */
			readcmd = NAND_CMD_READ0;
		} else {
			column -= 256;
			readcmd = NAND_CMD_READ1;
		}
		
		writeb(readcmd, info->regs + S3C2410_NFCMD);
	}
	writeb(command, info->regs + S3C2410_NFCMD);

	/* Set ALE and clear CLE to start address cycle */

	if (column != -1 || page_addr != -1) {

		/* Serially input address */
		if (column != -1) {
			/* Adjust columns for 16 bit buswidth */
			if (this->options & NAND_BUSWIDTH_16)
				column >>= 1;
			writeb(column, info->regs + S3C2410_NFADDR);
		}
		if (page_addr != -1) {
			writeb((unsigned char) (page_addr), info->regs + S3C2410_NFADDR);
			writeb((unsigned char) (page_addr >> 8), info->regs + S3C2410_NFADDR);
			/* One more address cycle for higher density devices */
			if (this->chipsize & 0x0c000000) 
				writeb((unsigned char) ((page_addr >> 16) & 0x0f),
				       info->regs + S3C2410_NFADDR);
		}
		/* Latch in address */
	}
	
	/* 
	 * program and erase have their own busy handlers 
	 * status and sequential in needs no delay
	*/
	switch (command) {
			
	case NAND_CMD_PAGEPROG:
	case NAND_CMD_ERASE1:
	case NAND_CMD_ERASE2:
	case NAND_CMD_SEQIN:
	case NAND_CMD_STATUS:
		return;

	case NAND_CMD_RESET:
		if (this->dev_ready)	
			break;

		udelay(this->chip_delay);
		writeb(NAND_CMD_STATUS, info->regs + S3C2410_NFCMD);

		while ( !(this->read_byte(mtd) & 0x40));
		return;

	/* This applies to read commands */	
	default:
		/* 
		 * If we don't have access to the busy pin, we apply the given
		 * command delay
		*/
		if (!this->dev_ready) {
			udelay (this->chip_delay);
			return;
		}	
	}
	
	/* Apply this short delay always to ensure that we do wait tWB in
	 * any case on any machine. */
	ndelay (100);
	/* wait until command is processed */
	while (!this->dev_ready(mtd));
}


/* 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;
}

/* 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;
}

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 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;
}


/* over-ride the standard functions for a little more speed? */

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 device *dev)
{
	struct s3c2410_nand_info *info = to_nand_info(dev);

	dev_set_drvdata(dev, 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)) {
		clk_disable(info->clk);
		clk_unuse(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	   = (char *)info->regs + S3C2410_NFDATA;
	chip->IO_ADDR_W    = (char *)info->regs + S3C2410_NFDATA;
	chip->hwcontrol    = s3c2410_nand_hwcontrol;
	chip->dev_ready    = s3c2410_nand_devready;
	chip->cmdfunc      = s3c2410_nand_command;
	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;

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

	if (hardware_ecc) {
		chip->correct_data  = s3c2410_nand_correct_data;
		chip->enable_hwecc  = s3c2410_nand_enable_hwecc;
		chip->calculate_ecc = s3c2410_nand_calculate_ecc;
		chip->eccmode	    = NAND_ECC_HW3_512;
		chip->autooob       = &nand_hw_eccoob;
	} else {
		chip->eccmode	    = 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 s3c2410_nand_probe(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct s3c2410_platform_nand *plat = to_nand_plat(dev);
	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", dev);

	info = kmalloc(sizeof(*info), GFP_KERNEL);
	if (info == NULL) {
		printk(KERN_ERR PFX "no memory for flash info\n");
		err = -ENOMEM;
		goto exit_error;
	}

	memzero(info, sizeof(*info));
	dev_set_drvdata(dev, info);

	spin_lock_init(&info->controller.lock);

	/* get the clock source and enable it */

	info->clk = clk_get(dev, "nand");
	if (IS_ERR(info->clk)) {
		printk(KERN_ERR PFX "failed to get clock");
		err = -ENOENT;
		goto exit_error;
	}

	clk_use(info->clk);
	clk_enable(info->clk);

	/* allocate and map the resource */

	res = pdev->resource;  /* assume that the flash has one resource */
	size = res->end - res->start + 1;

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

	if (info->area == NULL) {
		printk(KERN_ERR PFX "cannot reserve register region\n");
		err = -ENOENT;
		goto exit_error;
	}

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

	if (info->regs == NULL) {
		printk(KERN_ERR PFX "cannot reserve register region\n");
		err = -EIO;
		goto exit_error;
	}		

	printk(KERN_INFO PFX "mapped registers at %p\n", info->regs);

	/* initialise the hardware */

	err = s3c2410_nand_inithw(info, dev);
	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) {
		printk(KERN_ERR PFX "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++;
	}
	
	pr_debug("initialised ok\n");
	return 0;

 exit_error:
	s3c2410_nand_remove(dev);

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

static struct device_driver s3c2410_nand_driver = {
	.name		= "s3c2410-nand",
	.bus		= &platform_bus_type,
	.probe		= s3c2410_nand_probe,
	.remove		= s3c2410_nand_remove,
};

static int __init s3c2410_nand_init(void)
{
	printk("S3C2410 NAND Driver, (c) 2004 Simtec Electronics\n");
	return driver_register(&s3c2410_nand_driver);
}

static void __exit s3c2410_nand_exit(void)
{
	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("S3C2410 MTD NAND driver");