/* linux/drivers/mtd/nand/bf5xx_nand.c
 *
 * Copyright 2006-2007 Analog Devices Inc.
 *	http://blackfin.uclinux.org/
 *	Bryan Wu <bryan.wu@analog.com>
 *
 * Blackfin BF5xx on-chip NAND flash controler driver
 *
 * Derived from drivers/mtd/nand/s3c2410.c
 * Copyright (c) 2007 Ben Dooks <ben@simtec.co.uk>
 *
 * Derived from drivers/mtd/nand/cafe.c
 * Copyright © 2006 Red Hat, Inc.
 * Copyright © 2006 David Woodhouse <dwmw2@infradead.org>
 *
 * Changelog:
 *	12-Jun-2007  Bryan Wu:  Initial version
 *	18-Jul-2007  Bryan Wu:
 *		- ECC_HW and ECC_SW supported
 *		- DMA supported in ECC_HW
 *		- YAFFS tested as rootfs in both ECC_HW and ECC_SW
 *
 * TODO:
 * 	Enable JFFS2 over NAND as rootfs
 *
 * 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 <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/dma-mapping.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/bitops.h>

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

#include <asm/blackfin.h>
#include <asm/dma.h>
#include <asm/cacheflush.h>
#include <asm/nand.h>
#include <asm/portmux.h>

#define DRV_NAME	"bf5xx-nand"
#define DRV_VERSION	"1.2"
#define DRV_AUTHOR	"Bryan Wu <bryan.wu@analog.com>"
#define DRV_DESC	"BF5xx on-chip NAND FLash Controller Driver"

#ifdef CONFIG_MTD_NAND_BF5XX_HWECC
static int hardware_ecc = 1;
#else
static int hardware_ecc;
#endif

static unsigned short bfin_nfc_pin_req[] = {P_NAND_CE, P_NAND_RB, 0};

/*
 * Data structures for bf5xx nand flash controller driver
 */

/* bf5xx nand info */
struct bf5xx_nand_info {
	/* mtd info */
	struct nand_hw_control		controller;
	struct mtd_info			mtd;
	struct nand_chip		chip;

	/* platform info */
	struct bf5xx_nand_platform	*platform;

	/* device info */
	struct device			*device;

	/* DMA stuff */
	struct completion		dma_completion;
};

/*
 * Conversion functions
 */
static struct bf5xx_nand_info *mtd_to_nand_info(struct mtd_info *mtd)
{
	return container_of(mtd, struct bf5xx_nand_info, mtd);
}

static struct bf5xx_nand_info *to_nand_info(struct platform_device *pdev)
{
	return platform_get_drvdata(pdev);
}

static struct bf5xx_nand_platform *to_nand_plat(struct platform_device *pdev)
{
	return pdev->dev.platform_data;
}

/*
 * struct nand_chip interface function pointers
 */

/*
 * bf5xx_nand_hwcontrol
 *
 * Issue command and address cycles to the chip
 */
static void bf5xx_nand_hwcontrol(struct mtd_info *mtd, int cmd,
				   unsigned int ctrl)
{
	if (cmd == NAND_CMD_NONE)
		return;

	while (bfin_read_NFC_STAT() & WB_FULL)
		cpu_relax();

	if (ctrl & NAND_CLE)
		bfin_write_NFC_CMD(cmd);
	else
		bfin_write_NFC_ADDR(cmd);
	SSYNC();
}

/*
 * bf5xx_nand_devready()
 *
 * returns 0 if the nand is busy, 1 if it is ready
 */
static int bf5xx_nand_devready(struct mtd_info *mtd)
{
	unsigned short val = bfin_read_NFC_IRQSTAT();

	if ((val & NBUSYIRQ) == NBUSYIRQ)
		return 1;
	else
		return 0;
}

/*
 * ECC functions
 * These allow the bf5xx to use the controller's ECC
 * generator block to ECC the data as it passes through
 */

/*
 * ECC error correction function
 */
static int bf5xx_nand_correct_data_256(struct mtd_info *mtd, u_char *dat,
					u_char *read_ecc, u_char *calc_ecc)
{
	struct bf5xx_nand_info *info = mtd_to_nand_info(mtd);
	u32 syndrome[5];
	u32 calced, stored;
	int i;
	unsigned short failing_bit, failing_byte;
	u_char data;

	calced = calc_ecc[0] | (calc_ecc[1] << 8) | (calc_ecc[2] << 16);
	stored = read_ecc[0] | (read_ecc[1] << 8) | (read_ecc[2] << 16);

	syndrome[0] = (calced ^ stored);

	/*
	 * syndrome 0: all zero
	 * No error in data
	 * No action
	 */
	if (!syndrome[0] || !calced || !stored)
		return 0;

	/*
	 * sysdrome 0: only one bit is one
	 * ECC data was incorrect
	 * No action
	 */
	if (hweight32(syndrome[0]) == 1) {
		dev_err(info->device, "ECC data was incorrect!\n");
		return 1;
	}

	syndrome[1] = (calced & 0x7FF) ^ (stored & 0x7FF);
	syndrome[2] = (calced & 0x7FF) ^ ((calced >> 11) & 0x7FF);
	syndrome[3] = (stored & 0x7FF) ^ ((stored >> 11) & 0x7FF);
	syndrome[4] = syndrome[2] ^ syndrome[3];

	for (i = 0; i < 5; i++)
		dev_info(info->device, "syndrome[%d] 0x%08x\n", i, syndrome[i]);

	dev_info(info->device,
		"calced[0x%08x], stored[0x%08x]\n",
		calced, stored);

	/*
	 * sysdrome 0: exactly 11 bits are one, each parity
	 * and parity' pair is 1 & 0 or 0 & 1.
	 * 1-bit correctable error
	 * Correct the error
	 */
	if (hweight32(syndrome[0]) == 11 && syndrome[4] == 0x7FF) {
		dev_info(info->device,
			"1-bit correctable error, correct it.\n");
		dev_info(info->device,
			"syndrome[1] 0x%08x\n", syndrome[1]);

		failing_bit = syndrome[1] & 0x7;
		failing_byte = syndrome[1] >> 0x3;
		data = *(dat + failing_byte);
		data = data ^ (0x1 << failing_bit);
		*(dat + failing_byte) = data;

		return 0;
	}

	/*
	 * sysdrome 0: random data
	 * More than 1-bit error, non-correctable error
	 * Discard data, mark bad block
	 */
	dev_err(info->device,
		"More than 1-bit error, non-correctable error.\n");
	dev_err(info->device,
		"Please discard data, mark bad block\n");

	return 1;
}

static int bf5xx_nand_correct_data(struct mtd_info *mtd, u_char *dat,
					u_char *read_ecc, u_char *calc_ecc)
{
	struct bf5xx_nand_info *info = mtd_to_nand_info(mtd);
	struct bf5xx_nand_platform *plat = info->platform;
	unsigned short page_size = (plat->page_size ? 512 : 256);
	int ret;

	ret = bf5xx_nand_correct_data_256(mtd, dat, read_ecc, calc_ecc);

	/* If page size is 512, correct second 256 bytes */
	if (page_size == 512) {
		dat += 256;
		read_ecc += 8;
		calc_ecc += 8;
		ret = bf5xx_nand_correct_data_256(mtd, dat, read_ecc, calc_ecc);
	}

	return ret;
}

static void bf5xx_nand_enable_hwecc(struct mtd_info *mtd, int mode)
{
	return;
}

static int bf5xx_nand_calculate_ecc(struct mtd_info *mtd,
		const u_char *dat, u_char *ecc_code)
{
	struct bf5xx_nand_info *info = mtd_to_nand_info(mtd);
	struct bf5xx_nand_platform *plat = info->platform;
	u16 page_size = (plat->page_size ? 512 : 256);
	u16 ecc0, ecc1;
	u32 code[2];
	u8 *p;
	int bytes = 3, i;

	/* first 4 bytes ECC code for 256 page size */
	ecc0 = bfin_read_NFC_ECC0();
	ecc1 = bfin_read_NFC_ECC1();

	code[0] = (ecc0 & 0x3FF) | ((ecc1 & 0x3FF) << 11);

	dev_dbg(info->device, "returning ecc 0x%08x\n", code[0]);

	/* second 4 bytes ECC code for 512 page size */
	if (page_size == 512) {
		ecc0 = bfin_read_NFC_ECC2();
		ecc1 = bfin_read_NFC_ECC3();
		code[1] = (ecc0 & 0x3FF) | ((ecc1 & 0x3FF) << 11);
		bytes = 6;
		dev_dbg(info->device, "returning ecc 0x%08x\n", code[1]);
	}

	p = (u8 *)code;
	for (i = 0; i < bytes; i++)
		ecc_code[i] = p[i];

	return 0;
}

/*
 * PIO mode for buffer writing and reading
 */
static void bf5xx_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
	int i;
	unsigned short val;

	/*
	 * Data reads are requested by first writing to NFC_DATA_RD
	 * and then reading back from NFC_READ.
	 */
	for (i = 0; i < len; i++) {
		while (bfin_read_NFC_STAT() & WB_FULL)
			cpu_relax();

		/* Contents do not matter */
		bfin_write_NFC_DATA_RD(0x0000);
		SSYNC();

		while ((bfin_read_NFC_IRQSTAT() & RD_RDY) != RD_RDY)
			cpu_relax();

		buf[i] = bfin_read_NFC_READ();

		val = bfin_read_NFC_IRQSTAT();
		val |= RD_RDY;
		bfin_write_NFC_IRQSTAT(val);
		SSYNC();
	}
}

static uint8_t bf5xx_nand_read_byte(struct mtd_info *mtd)
{
	uint8_t val;

	bf5xx_nand_read_buf(mtd, &val, 1);

	return val;
}

static void bf5xx_nand_write_buf(struct mtd_info *mtd,
				const uint8_t *buf, int len)
{
	int i;

	for (i = 0; i < len; i++) {
		while (bfin_read_NFC_STAT() & WB_FULL)
			cpu_relax();

		bfin_write_NFC_DATA_WR(buf[i]);
		SSYNC();
	}
}

static void bf5xx_nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
{
	int i;
	u16 *p = (u16 *) buf;
	len >>= 1;

	/*
	 * Data reads are requested by first writing to NFC_DATA_RD
	 * and then reading back from NFC_READ.
	 */
	bfin_write_NFC_DATA_RD(0x5555);

	SSYNC();

	for (i = 0; i < len; i++)
		p[i] = bfin_read_NFC_READ();
}

static void bf5xx_nand_write_buf16(struct mtd_info *mtd,
				const uint8_t *buf, int len)
{
	int i;
	u16 *p = (u16 *) buf;
	len >>= 1;

	for (i = 0; i < len; i++)
		bfin_write_NFC_DATA_WR(p[i]);

	SSYNC();
}

/*
 * DMA functions for buffer writing and reading
 */
static irqreturn_t bf5xx_nand_dma_irq(int irq, void *dev_id)
{
	struct bf5xx_nand_info *info = dev_id;

	clear_dma_irqstat(CH_NFC);
	disable_dma(CH_NFC);
	complete(&info->dma_completion);

	return IRQ_HANDLED;
}

static int bf5xx_nand_dma_rw(struct mtd_info *mtd,
				uint8_t *buf, int is_read)
{
	struct bf5xx_nand_info *info = mtd_to_nand_info(mtd);
	struct bf5xx_nand_platform *plat = info->platform;
	unsigned short page_size = (plat->page_size ? 512 : 256);
	unsigned short val;

	dev_dbg(info->device, " mtd->%p, buf->%p, is_read %d\n",
			mtd, buf, is_read);

	/*
	 * Before starting a dma transfer, be sure to invalidate/flush
	 * the cache over the address range of your DMA buffer to
	 * prevent cache coherency problems. Otherwise very subtle bugs
	 * can be introduced to your driver.
	 */
	if (is_read)
		invalidate_dcache_range((unsigned int)buf,
				(unsigned int)(buf + page_size));
	else
		flush_dcache_range((unsigned int)buf,
				(unsigned int)(buf + page_size));

	/*
	 * This register must be written before each page is
	 * transferred to generate the correct ECC register
	 * values.
	 */
	bfin_write_NFC_RST(0x1);
	SSYNC();

	disable_dma(CH_NFC);
	clear_dma_irqstat(CH_NFC);

	/* setup DMA register with Blackfin DMA API */
	set_dma_config(CH_NFC, 0x0);
	set_dma_start_addr(CH_NFC, (unsigned long) buf);
	set_dma_x_count(CH_NFC, (page_size >> 2));
	set_dma_x_modify(CH_NFC, 4);

	/* setup write or read operation */
	val = DI_EN | WDSIZE_32;
	if (is_read)
		val |= WNR;
	set_dma_config(CH_NFC, val);
	enable_dma(CH_NFC);

	/* Start PAGE read/write operation */
	if (is_read)
		bfin_write_NFC_PGCTL(0x1);
	else
		bfin_write_NFC_PGCTL(0x2);
	wait_for_completion(&info->dma_completion);

	return 0;
}

static void bf5xx_nand_dma_read_buf(struct mtd_info *mtd,
					uint8_t *buf, int len)
{
	struct bf5xx_nand_info *info = mtd_to_nand_info(mtd);
	struct bf5xx_nand_platform *plat = info->platform;
	unsigned short page_size = (plat->page_size ? 512 : 256);

	dev_dbg(info->device, "mtd->%p, buf->%p, int %d\n", mtd, buf, len);

	if (len == page_size)
		bf5xx_nand_dma_rw(mtd, buf, 1);
	else
		bf5xx_nand_read_buf(mtd, buf, len);
}

static void bf5xx_nand_dma_write_buf(struct mtd_info *mtd,
				const uint8_t *buf, int len)
{
	struct bf5xx_nand_info *info = mtd_to_nand_info(mtd);
	struct bf5xx_nand_platform *plat = info->platform;
	unsigned short page_size = (plat->page_size ? 512 : 256);

	dev_dbg(info->device, "mtd->%p, buf->%p, len %d\n", mtd, buf, len);

	if (len == page_size)
		bf5xx_nand_dma_rw(mtd, (uint8_t *)buf, 0);
	else
		bf5xx_nand_write_buf(mtd, buf, len);
}

/*
 * System initialization functions
 */

static int bf5xx_nand_dma_init(struct bf5xx_nand_info *info)
{
	int ret;
	unsigned short val;

	/* Do not use dma */
	if (!hardware_ecc)
		return 0;

	init_completion(&info->dma_completion);

	/* Setup DMAC1 channel mux for NFC which shared with SDH */
	val = bfin_read_DMAC1_PERIMUX();
	val &= 0xFFFE;
	bfin_write_DMAC1_PERIMUX(val);
	SSYNC();

	/* Request NFC DMA channel */
	ret = request_dma(CH_NFC, "BF5XX NFC driver");
	if (ret < 0) {
		dev_err(info->device, " unable to get DMA channel\n");
		return ret;
	}

	set_dma_callback(CH_NFC, (void *) bf5xx_nand_dma_irq, (void *) info);

	/* Turn off the DMA channel first */
	disable_dma(CH_NFC);
	return 0;
}

/*
 * BF5XX NFC hardware initialization
 *  - pin mux setup
 *  - clear interrupt status
 */
static int bf5xx_nand_hw_init(struct bf5xx_nand_info *info)
{
	int err = 0;
	unsigned short val;
	struct bf5xx_nand_platform *plat = info->platform;

	/* setup NFC_CTL register */
	dev_info(info->device,
		"page_size=%d, data_width=%d, wr_dly=%d, rd_dly=%d\n",
		(plat->page_size ? 512 : 256),
		(plat->data_width ? 16 : 8),
		plat->wr_dly, plat->rd_dly);

	val = (plat->page_size << NFC_PG_SIZE_OFFSET) |
		(plat->data_width << NFC_NWIDTH_OFFSET) |
		(plat->rd_dly << NFC_RDDLY_OFFSET) |
		(plat->rd_dly << NFC_WRDLY_OFFSET);
	dev_dbg(info->device, "NFC_CTL is 0x%04x\n", val);

	bfin_write_NFC_CTL(val);
	SSYNC();

	/* clear interrupt status */
	bfin_write_NFC_IRQMASK(0x0);
	SSYNC();
	val = bfin_read_NFC_IRQSTAT();
	bfin_write_NFC_IRQSTAT(val);
	SSYNC();

	if (peripheral_request_list(bfin_nfc_pin_req, DRV_NAME)) {
		printk(KERN_ERR DRV_NAME
		": Requesting Peripherals failed\n");
		return -EFAULT;
	}

	/* DMA initialization  */
	if (bf5xx_nand_dma_init(info))
		err = -ENXIO;

	return err;
}

/*
 * Device management interface
 */
static int bf5xx_nand_add_partition(struct bf5xx_nand_info *info)
{
	struct mtd_info *mtd = &info->mtd;

#ifdef CONFIG_MTD_PARTITIONS
	struct mtd_partition *parts = info->platform->partitions;
	int nr = info->platform->nr_partitions;

	return add_mtd_partitions(mtd, parts, nr);
#else
	return add_mtd_device(mtd);
#endif
}

static int bf5xx_nand_remove(struct platform_device *pdev)
{
	struct bf5xx_nand_info *info = to_nand_info(pdev);
	struct mtd_info *mtd = NULL;

	platform_set_drvdata(pdev, NULL);

	/* first thing we need to do is release all our mtds
	 * and their partitions, then go through freeing the
	 * resources used
	 */
	mtd = &info->mtd;
	if (mtd) {
		nand_release(mtd);
		kfree(mtd);
	}

	peripheral_free_list(bfin_nfc_pin_req);

	/* free the common resources */
	kfree(info);

	return 0;
}

/*
 * bf5xx_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 bf5xx_nand_probe(struct platform_device *pdev)
{
	struct bf5xx_nand_platform *plat = to_nand_plat(pdev);
	struct bf5xx_nand_info *info = NULL;
	struct nand_chip *chip = NULL;
	struct mtd_info *mtd = NULL;
	int err = 0;

	dev_dbg(&pdev->dev, "(%p)\n", pdev);

	if (!plat) {
		dev_err(&pdev->dev, "no platform specific information\n");
		goto exit_error;
	}

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

	platform_set_drvdata(pdev, info);

	spin_lock_init(&info->controller.lock);
	init_waitqueue_head(&info->controller.wq);

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

	/* initialise chip data struct */
	chip = &info->chip;

	if (plat->data_width)
		chip->options |= NAND_BUSWIDTH_16;

	chip->options |= NAND_CACHEPRG | NAND_SKIP_BBTSCAN;

	chip->read_buf = (plat->data_width) ?
		bf5xx_nand_read_buf16 : bf5xx_nand_read_buf;
	chip->write_buf = (plat->data_width) ?
		bf5xx_nand_write_buf16 : bf5xx_nand_write_buf;

	chip->read_byte    = bf5xx_nand_read_byte;

	chip->cmd_ctrl     = bf5xx_nand_hwcontrol;
	chip->dev_ready    = bf5xx_nand_devready;

	chip->priv	   = &info->mtd;
	chip->controller   = &info->controller;

	chip->IO_ADDR_R    = (void __iomem *) NFC_READ;
	chip->IO_ADDR_W    = (void __iomem *) NFC_DATA_WR;

	chip->chip_delay   = 0;

	/* initialise mtd info data struct */
	mtd 		= &info->mtd;
	mtd->priv	= chip;
	mtd->owner	= THIS_MODULE;

	/* initialise the hardware */
	err = bf5xx_nand_hw_init(info);
	if (err != 0)
		goto exit_error;

	/* setup hardware ECC data struct */
	if (hardware_ecc) {
		if (plat->page_size == NFC_PG_SIZE_256) {
			chip->ecc.bytes = 3;
			chip->ecc.size = 256;
		} else if (plat->page_size == NFC_PG_SIZE_512) {
			chip->ecc.bytes = 6;
			chip->ecc.size = 512;
		}

		chip->read_buf      = bf5xx_nand_dma_read_buf;
		chip->write_buf     = bf5xx_nand_dma_write_buf;
		chip->ecc.calculate = bf5xx_nand_calculate_ecc;
		chip->ecc.correct   = bf5xx_nand_correct_data;
		chip->ecc.mode	    = NAND_ECC_HW;
		chip->ecc.hwctl	    = bf5xx_nand_enable_hwecc;
	} else {
		chip->ecc.mode	    = NAND_ECC_SOFT;
	}

	/* scan hardware nand chip and setup mtd info data struct */
	if (nand_scan(mtd, 1)) {
		err = -ENXIO;
		goto exit_error;
	}

	/* add NAND partition */
	bf5xx_nand_add_partition(info);

	dev_dbg(&pdev->dev, "initialised ok\n");
	return 0;

exit_error:
	bf5xx_nand_remove(pdev);

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

/* PM Support */
#ifdef CONFIG_PM

static int bf5xx_nand_suspend(struct platform_device *dev, pm_message_t pm)
{
	struct bf5xx_nand_info *info = platform_get_drvdata(dev);

	return 0;
}

static int bf5xx_nand_resume(struct platform_device *dev)
{
	struct bf5xx_nand_info *info = platform_get_drvdata(dev);

	if (info)
		bf5xx_nand_hw_init(info);

	return 0;
}

#else
#define bf5xx_nand_suspend NULL
#define bf5xx_nand_resume NULL
#endif

/* driver device registration */
static struct platform_driver bf5xx_nand_driver = {
	.probe		= bf5xx_nand_probe,
	.remove		= bf5xx_nand_remove,
	.suspend	= bf5xx_nand_suspend,
	.resume		= bf5xx_nand_resume,
	.driver		= {
		.name	= DRV_NAME,
		.owner	= THIS_MODULE,
	},
};

static int __init bf5xx_nand_init(void)
{
	printk(KERN_INFO "%s, Version %s (c) 2007 Analog Devices, Inc.\n",
		DRV_DESC, DRV_VERSION);

	return platform_driver_register(&bf5xx_nand_driver);
}

static void __exit bf5xx_nand_exit(void)
{
	platform_driver_unregister(&bf5xx_nand_driver);
}

module_init(bf5xx_nand_init);
module_exit(bf5xx_nand_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);