/*
 * drivers/mtd/nand/pxa3xx_nand.c
 *
 * Copyright © 2005 Intel Corporation
 * Copyright © 2006 Marvell International Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>
#include <linux/io.h>
#include <linux/irq.h>

#include <mach/dma.h>
#include <mach/pxa3xx_nand.h>

#define	CHIP_DELAY_TIMEOUT	(2 * HZ/10)

/* registers and bit definitions */
#define NDCR		(0x00) /* Control register */
#define NDTR0CS0	(0x04) /* Timing Parameter 0 for CS0 */
#define NDTR1CS0	(0x0C) /* Timing Parameter 1 for CS0 */
#define NDSR		(0x14) /* Status Register */
#define NDPCR		(0x18) /* Page Count Register */
#define NDBDR0		(0x1C) /* Bad Block Register 0 */
#define NDBDR1		(0x20) /* Bad Block Register 1 */
#define NDDB		(0x40) /* Data Buffer */
#define NDCB0		(0x48) /* Command Buffer0 */
#define NDCB1		(0x4C) /* Command Buffer1 */
#define NDCB2		(0x50) /* Command Buffer2 */

#define NDCR_SPARE_EN		(0x1 << 31)
#define NDCR_ECC_EN		(0x1 << 30)
#define NDCR_DMA_EN		(0x1 << 29)
#define NDCR_ND_RUN		(0x1 << 28)
#define NDCR_DWIDTH_C		(0x1 << 27)
#define NDCR_DWIDTH_M		(0x1 << 26)
#define NDCR_PAGE_SZ		(0x1 << 24)
#define NDCR_NCSX		(0x1 << 23)
#define NDCR_ND_MODE		(0x3 << 21)
#define NDCR_NAND_MODE   	(0x0)
#define NDCR_CLR_PG_CNT		(0x1 << 20)
#define NDCR_CLR_ECC		(0x1 << 19)
#define NDCR_RD_ID_CNT_MASK	(0x7 << 16)
#define NDCR_RD_ID_CNT(x)	(((x) << 16) & NDCR_RD_ID_CNT_MASK)

#define NDCR_RA_START		(0x1 << 15)
#define NDCR_PG_PER_BLK		(0x1 << 14)
#define NDCR_ND_ARB_EN		(0x1 << 12)

#define NDSR_MASK		(0xfff)
#define NDSR_RDY		(0x1 << 11)
#define NDSR_CS0_PAGED		(0x1 << 10)
#define NDSR_CS1_PAGED		(0x1 << 9)
#define NDSR_CS0_CMDD		(0x1 << 8)
#define NDSR_CS1_CMDD		(0x1 << 7)
#define NDSR_CS0_BBD		(0x1 << 6)
#define NDSR_CS1_BBD		(0x1 << 5)
#define NDSR_DBERR		(0x1 << 4)
#define NDSR_SBERR		(0x1 << 3)
#define NDSR_WRDREQ		(0x1 << 2)
#define NDSR_RDDREQ		(0x1 << 1)
#define NDSR_WRCMDREQ		(0x1)

#define NDCB0_AUTO_RS		(0x1 << 25)
#define NDCB0_CSEL		(0x1 << 24)
#define NDCB0_CMD_TYPE_MASK	(0x7 << 21)
#define NDCB0_CMD_TYPE(x)	(((x) << 21) & NDCB0_CMD_TYPE_MASK)
#define NDCB0_NC		(0x1 << 20)
#define NDCB0_DBC		(0x1 << 19)
#define NDCB0_ADDR_CYC_MASK	(0x7 << 16)
#define NDCB0_ADDR_CYC(x)	(((x) << 16) & NDCB0_ADDR_CYC_MASK)
#define NDCB0_CMD2_MASK		(0xff << 8)
#define NDCB0_CMD1_MASK		(0xff)
#define NDCB0_ADDR_CYC_SHIFT	(16)

/* macros for registers read/write */
#define nand_writel(info, off, val)	\
	__raw_writel((val), (info)->mmio_base + (off))

#define nand_readl(info, off)		\
	__raw_readl((info)->mmio_base + (off))

/* error code and state */
enum {
	ERR_NONE	= 0,
	ERR_DMABUSERR	= -1,
	ERR_SENDCMD	= -2,
	ERR_DBERR	= -3,
	ERR_BBERR	= -4,
	ERR_SBERR	= -5,
};

enum {
	STATE_READY	= 0,
	STATE_CMD_HANDLE,
	STATE_DMA_READING,
	STATE_DMA_WRITING,
	STATE_DMA_DONE,
	STATE_PIO_READING,
	STATE_PIO_WRITING,
};

struct pxa3xx_nand_info {
	struct nand_chip	nand_chip;

	struct platform_device	 *pdev;
	const struct pxa3xx_nand_flash *flash_info;

	struct clk		*clk;
	void __iomem		*mmio_base;
	unsigned long		mmio_phys;

	unsigned int 		buf_start;
	unsigned int		buf_count;

	/* DMA information */
	int			drcmr_dat;
	int			drcmr_cmd;

	unsigned char		*data_buff;
	dma_addr_t 		data_buff_phys;
	size_t			data_buff_size;
	int 			data_dma_ch;
	struct pxa_dma_desc	*data_desc;
	dma_addr_t 		data_desc_addr;

	uint32_t		reg_ndcr;

	/* saved column/page_addr during CMD_SEQIN */
	int			seqin_column;
	int			seqin_page_addr;

	/* relate to the command */
	unsigned int		state;

	int			use_ecc;	/* use HW ECC ? */
	int			use_dma;	/* use DMA ? */

	size_t			data_size;	/* data size in FIFO */
	int 			retcode;
	struct completion 	cmd_complete;

	/* generated NDCBx register values */
	uint32_t		ndcb0;
	uint32_t		ndcb1;
	uint32_t		ndcb2;

	/* calculated from pxa3xx_nand_flash data */
	size_t		oob_size;
	size_t		read_id_bytes;

	unsigned int	col_addr_cycles;
	unsigned int	row_addr_cycles;
};

static int use_dma = 1;
module_param(use_dma, bool, 0444);
MODULE_PARM_DESC(use_dma, "enable DMA for data transfering to/from NAND HW");

/*
 * Default NAND flash controller configuration setup by the
 * bootloader. This configuration is used only when pdata->keep_config is set
 */
static struct pxa3xx_nand_timing default_timing;
static struct pxa3xx_nand_flash default_flash;

static struct pxa3xx_nand_cmdset smallpage_cmdset = {
	.read1		= 0x0000,
	.read2		= 0x0050,
	.program	= 0x1080,
	.read_status	= 0x0070,
	.read_id	= 0x0090,
	.erase		= 0xD060,
	.reset		= 0x00FF,
	.lock		= 0x002A,
	.unlock		= 0x2423,
	.lock_status	= 0x007A,
};

static struct pxa3xx_nand_cmdset largepage_cmdset = {
	.read1		= 0x3000,
	.read2		= 0x0050,
	.program	= 0x1080,
	.read_status	= 0x0070,
	.read_id	= 0x0090,
	.erase		= 0xD060,
	.reset		= 0x00FF,
	.lock		= 0x002A,
	.unlock		= 0x2423,
	.lock_status	= 0x007A,
};

#ifdef CONFIG_MTD_NAND_PXA3xx_BUILTIN
static struct pxa3xx_nand_timing samsung512MbX16_timing = {
	.tCH	= 10,
	.tCS	= 0,
	.tWH	= 20,
	.tWP	= 40,
	.tRH	= 30,
	.tRP	= 40,
	.tR	= 11123,
	.tWHR	= 110,
	.tAR	= 10,
};

static struct pxa3xx_nand_flash samsung512MbX16 = {
	.timing		= &samsung512MbX16_timing,
	.cmdset		= &smallpage_cmdset,
	.page_per_block	= 32,
	.page_size	= 512,
	.flash_width	= 16,
	.dfc_width	= 16,
	.num_blocks	= 4096,
	.chip_id	= 0x46ec,
};

static struct pxa3xx_nand_timing micron_timing = {
	.tCH	= 10,
	.tCS	= 25,
	.tWH	= 15,
	.tWP	= 25,
	.tRH	= 15,
	.tRP	= 30,
	.tR	= 25000,
	.tWHR	= 60,
	.tAR	= 10,
};

static struct pxa3xx_nand_flash micron1GbX8 = {
	.timing		= &micron_timing,
	.cmdset		= &largepage_cmdset,
	.page_per_block	= 64,
	.page_size	= 2048,
	.flash_width	= 8,
	.dfc_width	= 8,
	.num_blocks	= 1024,
	.chip_id	= 0xa12c,
};

static struct pxa3xx_nand_flash micron1GbX16 = {
	.timing		= &micron_timing,
	.cmdset		= &largepage_cmdset,
	.page_per_block	= 64,
	.page_size	= 2048,
	.flash_width	= 16,
	.dfc_width	= 16,
	.num_blocks	= 1024,
	.chip_id	= 0xb12c,
};

static struct pxa3xx_nand_timing stm2GbX16_timing = {
	.tCH = 10,
	.tCS = 35,
	.tWH = 15,
	.tWP = 25,
	.tRH = 15,
	.tRP = 25,
	.tR = 25000,
	.tWHR = 60,
	.tAR = 10,
};

static struct pxa3xx_nand_flash stm2GbX16 = {
	.timing = &stm2GbX16_timing,
	.cmdset	= &largepage_cmdset,
	.page_per_block = 64,
	.page_size = 2048,
	.flash_width = 16,
	.dfc_width = 16,
	.num_blocks = 2048,
	.chip_id = 0xba20,
};

static struct pxa3xx_nand_flash *builtin_flash_types[] = {
	&samsung512MbX16,
	&micron1GbX8,
	&micron1GbX16,
	&stm2GbX16,
};
#endif /* CONFIG_MTD_NAND_PXA3xx_BUILTIN */

#define NDTR0_tCH(c)	(min((c), 7) << 19)
#define NDTR0_tCS(c)	(min((c), 7) << 16)
#define NDTR0_tWH(c)	(min((c), 7) << 11)
#define NDTR0_tWP(c)	(min((c), 7) << 8)
#define NDTR0_tRH(c)	(min((c), 7) << 3)
#define NDTR0_tRP(c)	(min((c), 7) << 0)

#define NDTR1_tR(c)	(min((c), 65535) << 16)
#define NDTR1_tWHR(c)	(min((c), 15) << 4)
#define NDTR1_tAR(c)	(min((c), 15) << 0)

#define tCH_NDTR0(r)	(((r) >> 19) & 0x7)
#define tCS_NDTR0(r)	(((r) >> 16) & 0x7)
#define tWH_NDTR0(r)	(((r) >> 11) & 0x7)
#define tWP_NDTR0(r)	(((r) >> 8) & 0x7)
#define tRH_NDTR0(r)	(((r) >> 3) & 0x7)
#define tRP_NDTR0(r)	(((r) >> 0) & 0x7)

#define tR_NDTR1(r)	(((r) >> 16) & 0xffff)
#define tWHR_NDTR1(r)	(((r) >> 4) & 0xf)
#define tAR_NDTR1(r)	(((r) >> 0) & 0xf)

/* convert nano-seconds to nand flash controller clock cycles */
#define ns2cycle(ns, clk)	(int)(((ns) * (clk / 1000000) / 1000) - 1)

/* convert nand flash controller clock cycles to nano-seconds */
#define cycle2ns(c, clk)	((((c) + 1) * 1000000 + clk / 500) / (clk / 1000))

static void pxa3xx_nand_set_timing(struct pxa3xx_nand_info *info,
				   const struct pxa3xx_nand_timing *t)
{
	unsigned long nand_clk = clk_get_rate(info->clk);
	uint32_t ndtr0, ndtr1;

	ndtr0 = NDTR0_tCH(ns2cycle(t->tCH, nand_clk)) |
		NDTR0_tCS(ns2cycle(t->tCS, nand_clk)) |
		NDTR0_tWH(ns2cycle(t->tWH, nand_clk)) |
		NDTR0_tWP(ns2cycle(t->tWP, nand_clk)) |
		NDTR0_tRH(ns2cycle(t->tRH, nand_clk)) |
		NDTR0_tRP(ns2cycle(t->tRP, nand_clk));

	ndtr1 = NDTR1_tR(ns2cycle(t->tR, nand_clk)) |
		NDTR1_tWHR(ns2cycle(t->tWHR, nand_clk)) |
		NDTR1_tAR(ns2cycle(t->tAR, nand_clk));

	nand_writel(info, NDTR0CS0, ndtr0);
	nand_writel(info, NDTR1CS0, ndtr1);
}

#define WAIT_EVENT_TIMEOUT	10

static int wait_for_event(struct pxa3xx_nand_info *info, uint32_t event)
{
	int timeout = WAIT_EVENT_TIMEOUT;
	uint32_t ndsr;

	while (timeout--) {
		ndsr = nand_readl(info, NDSR) & NDSR_MASK;
		if (ndsr & event) {
			nand_writel(info, NDSR, ndsr);
			return 0;
		}
		udelay(10);
	}

	return -ETIMEDOUT;
}

static int prepare_read_prog_cmd(struct pxa3xx_nand_info *info,
			uint16_t cmd, int column, int page_addr)
{
	const struct pxa3xx_nand_flash *f = info->flash_info;
	const struct pxa3xx_nand_cmdset *cmdset = f->cmdset;

	/* calculate data size */
	switch (f->page_size) {
	case 2048:
		info->data_size = (info->use_ecc) ? 2088 : 2112;
		break;
	case 512:
		info->data_size = (info->use_ecc) ? 520 : 528;
		break;
	default:
		return -EINVAL;
	}

	/* generate values for NDCBx registers */
	info->ndcb0 = cmd | ((cmd & 0xff00) ? NDCB0_DBC : 0);
	info->ndcb1 = 0;
	info->ndcb2 = 0;
	info->ndcb0 |= NDCB0_ADDR_CYC(info->row_addr_cycles + info->col_addr_cycles);

	if (info->col_addr_cycles == 2) {
		/* large block, 2 cycles for column address
		 * row address starts from 3rd cycle
		 */
		info->ndcb1 |= page_addr << 16;
		if (info->row_addr_cycles == 3)
			info->ndcb2 = (page_addr >> 16) & 0xff;
	} else
		/* small block, 1 cycles for column address
		 * row address starts from 2nd cycle
		 */
		info->ndcb1 = page_addr << 8;

	if (cmd == cmdset->program)
		info->ndcb0 |= NDCB0_CMD_TYPE(1) | NDCB0_AUTO_RS;

	return 0;
}

static int prepare_erase_cmd(struct pxa3xx_nand_info *info,
			uint16_t cmd, int page_addr)
{
	info->ndcb0 = cmd | ((cmd & 0xff00) ? NDCB0_DBC : 0);
	info->ndcb0 |= NDCB0_CMD_TYPE(2) | NDCB0_AUTO_RS | NDCB0_ADDR_CYC(3);
	info->ndcb1 = page_addr;
	info->ndcb2 = 0;
	return 0;
}

static int prepare_other_cmd(struct pxa3xx_nand_info *info, uint16_t cmd)
{
	const struct pxa3xx_nand_cmdset *cmdset = info->flash_info->cmdset;

	info->ndcb0 = cmd | ((cmd & 0xff00) ? NDCB0_DBC : 0);
	info->ndcb1 = 0;
	info->ndcb2 = 0;

	if (cmd == cmdset->read_id) {
		info->ndcb0 |= NDCB0_CMD_TYPE(3);
		info->data_size = 8;
	} else if (cmd == cmdset->read_status) {
		info->ndcb0 |= NDCB0_CMD_TYPE(4);
		info->data_size = 8;
	} else if (cmd == cmdset->reset || cmd == cmdset->lock ||
		   cmd == cmdset->unlock) {
		info->ndcb0 |= NDCB0_CMD_TYPE(5);
	} else
		return -EINVAL;

	return 0;
}

static void enable_int(struct pxa3xx_nand_info *info, uint32_t int_mask)
{
	uint32_t ndcr;

	ndcr = nand_readl(info, NDCR);
	nand_writel(info, NDCR, ndcr & ~int_mask);
}

static void disable_int(struct pxa3xx_nand_info *info, uint32_t int_mask)
{
	uint32_t ndcr;

	ndcr = nand_readl(info, NDCR);
	nand_writel(info, NDCR, ndcr | int_mask);
}

/* NOTE: it is a must to set ND_RUN firstly, then write command buffer
 * otherwise, it does not work
 */
static int write_cmd(struct pxa3xx_nand_info *info)
{
	uint32_t ndcr;

	/* clear status bits and run */
	nand_writel(info, NDSR, NDSR_MASK);

	ndcr = info->reg_ndcr;

	ndcr |= info->use_ecc ? NDCR_ECC_EN : 0;
	ndcr |= info->use_dma ? NDCR_DMA_EN : 0;
	ndcr |= NDCR_ND_RUN;

	nand_writel(info, NDCR, ndcr);

	if (wait_for_event(info, NDSR_WRCMDREQ)) {
		printk(KERN_ERR "timed out writing command\n");
		return -ETIMEDOUT;
	}

	nand_writel(info, NDCB0, info->ndcb0);
	nand_writel(info, NDCB0, info->ndcb1);
	nand_writel(info, NDCB0, info->ndcb2);
	return 0;
}

static int handle_data_pio(struct pxa3xx_nand_info *info)
{
	int ret, timeout = CHIP_DELAY_TIMEOUT;

	switch (info->state) {
	case STATE_PIO_WRITING:
		__raw_writesl(info->mmio_base + NDDB, info->data_buff,
				DIV_ROUND_UP(info->data_size, 4));

		enable_int(info, NDSR_CS0_BBD | NDSR_CS0_CMDD);

		ret = wait_for_completion_timeout(&info->cmd_complete, timeout);
		if (!ret) {
			printk(KERN_ERR "program command time out\n");
			return -1;
		}
		break;
	case STATE_PIO_READING:
		__raw_readsl(info->mmio_base + NDDB, info->data_buff,
				DIV_ROUND_UP(info->data_size, 4));
		break;
	default:
		printk(KERN_ERR "%s: invalid state %d\n", __func__,
				info->state);
		return -EINVAL;
	}

	info->state = STATE_READY;
	return 0;
}

static void start_data_dma(struct pxa3xx_nand_info *info, int dir_out)
{
	struct pxa_dma_desc *desc = info->data_desc;
	int dma_len = ALIGN(info->data_size, 32);

	desc->ddadr = DDADR_STOP;
	desc->dcmd = DCMD_ENDIRQEN | DCMD_WIDTH4 | DCMD_BURST32 | dma_len;

	if (dir_out) {
		desc->dsadr = info->data_buff_phys;
		desc->dtadr = info->mmio_phys + NDDB;
		desc->dcmd |= DCMD_INCSRCADDR | DCMD_FLOWTRG;
	} else {
		desc->dtadr = info->data_buff_phys;
		desc->dsadr = info->mmio_phys + NDDB;
		desc->dcmd |= DCMD_INCTRGADDR | DCMD_FLOWSRC;
	}

	DRCMR(info->drcmr_dat) = DRCMR_MAPVLD | info->data_dma_ch;
	DDADR(info->data_dma_ch) = info->data_desc_addr;
	DCSR(info->data_dma_ch) |= DCSR_RUN;
}

static void pxa3xx_nand_data_dma_irq(int channel, void *data)
{
	struct pxa3xx_nand_info *info = data;
	uint32_t dcsr;

	dcsr = DCSR(channel);
	DCSR(channel) = dcsr;

	if (dcsr & DCSR_BUSERR) {
		info->retcode = ERR_DMABUSERR;
		complete(&info->cmd_complete);
	}

	if (info->state == STATE_DMA_WRITING) {
		info->state = STATE_DMA_DONE;
		enable_int(info, NDSR_CS0_BBD | NDSR_CS0_CMDD);
	} else {
		info->state = STATE_READY;
		complete(&info->cmd_complete);
	}
}

static irqreturn_t pxa3xx_nand_irq(int irq, void *devid)
{
	struct pxa3xx_nand_info *info = devid;
	unsigned int status;

	status = nand_readl(info, NDSR);

	if (status & (NDSR_RDDREQ | NDSR_DBERR | NDSR_SBERR)) {
		if (status & NDSR_DBERR)
			info->retcode = ERR_DBERR;
		else if (status & NDSR_SBERR)
			info->retcode = ERR_SBERR;

		disable_int(info, NDSR_RDDREQ | NDSR_DBERR | NDSR_SBERR);

		if (info->use_dma) {
			info->state = STATE_DMA_READING;
			start_data_dma(info, 0);
		} else {
			info->state = STATE_PIO_READING;
			complete(&info->cmd_complete);
		}
	} else if (status & NDSR_WRDREQ) {
		disable_int(info, NDSR_WRDREQ);
		if (info->use_dma) {
			info->state = STATE_DMA_WRITING;
			start_data_dma(info, 1);
		} else {
			info->state = STATE_PIO_WRITING;
			complete(&info->cmd_complete);
		}
	} else if (status & (NDSR_CS0_BBD | NDSR_CS0_CMDD)) {
		if (status & NDSR_CS0_BBD)
			info->retcode = ERR_BBERR;

		disable_int(info, NDSR_CS0_BBD | NDSR_CS0_CMDD);
		info->state = STATE_READY;
		complete(&info->cmd_complete);
	}
	nand_writel(info, NDSR, status);
	return IRQ_HANDLED;
}

static int pxa3xx_nand_do_cmd(struct pxa3xx_nand_info *info, uint32_t event)
{
	uint32_t ndcr;
	int ret, timeout = CHIP_DELAY_TIMEOUT;

	if (write_cmd(info)) {
		info->retcode = ERR_SENDCMD;
		goto fail_stop;
	}

	info->state = STATE_CMD_HANDLE;

	enable_int(info, event);

	ret = wait_for_completion_timeout(&info->cmd_complete, timeout);
	if (!ret) {
		printk(KERN_ERR "command execution timed out\n");
		info->retcode = ERR_SENDCMD;
		goto fail_stop;
	}

	if (info->use_dma == 0 && info->data_size > 0)
		if (handle_data_pio(info))
			goto fail_stop;

	return 0;

fail_stop:
	ndcr = nand_readl(info, NDCR);
	nand_writel(info, NDCR, ndcr & ~NDCR_ND_RUN);
	udelay(10);
	return -ETIMEDOUT;
}

static int pxa3xx_nand_dev_ready(struct mtd_info *mtd)
{
	struct pxa3xx_nand_info *info = mtd->priv;
	return (nand_readl(info, NDSR) & NDSR_RDY) ? 1 : 0;
}

static inline int is_buf_blank(uint8_t *buf, size_t len)
{
	for (; len > 0; len--)
		if (*buf++ != 0xff)
			return 0;
	return 1;
}

static void pxa3xx_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
				int column, int page_addr)
{
	struct pxa3xx_nand_info *info = mtd->priv;
	const struct pxa3xx_nand_flash *flash_info = info->flash_info;
	const struct pxa3xx_nand_cmdset *cmdset = flash_info->cmdset;
	int ret;

	info->use_dma = (use_dma) ? 1 : 0;
	info->use_ecc = 0;
	info->data_size = 0;
	info->state = STATE_READY;

	init_completion(&info->cmd_complete);

	switch (command) {
	case NAND_CMD_READOOB:
		/* disable HW ECC to get all the OOB data */
		info->buf_count = mtd->writesize + mtd->oobsize;
		info->buf_start = mtd->writesize + column;
		memset(info->data_buff, 0xFF, info->buf_count);

		if (prepare_read_prog_cmd(info, cmdset->read1, column, page_addr))
			break;

		pxa3xx_nand_do_cmd(info, NDSR_RDDREQ | NDSR_DBERR | NDSR_SBERR);

		/* We only are OOB, so if the data has error, does not matter */
		if (info->retcode == ERR_DBERR)
			info->retcode = ERR_NONE;
		break;

	case NAND_CMD_READ0:
		info->use_ecc = 1;
		info->retcode = ERR_NONE;
		info->buf_start = column;
		info->buf_count = mtd->writesize + mtd->oobsize;
		memset(info->data_buff, 0xFF, info->buf_count);

		if (prepare_read_prog_cmd(info, cmdset->read1, column, page_addr))
			break;

		pxa3xx_nand_do_cmd(info, NDSR_RDDREQ | NDSR_DBERR | NDSR_SBERR);

		if (info->retcode == ERR_DBERR) {
			/* for blank page (all 0xff), HW will calculate its ECC as
			 * 0, which is different from the ECC information within
			 * OOB, ignore such double bit errors
			 */
			if (is_buf_blank(info->data_buff, mtd->writesize))
				info->retcode = ERR_NONE;
		}
		break;
	case NAND_CMD_SEQIN:
		info->buf_start = column;
		info->buf_count = mtd->writesize + mtd->oobsize;
		memset(info->data_buff, 0xff, info->buf_count);

		/* save column/page_addr for next CMD_PAGEPROG */
		info->seqin_column = column;
		info->seqin_page_addr = page_addr;
		break;
	case NAND_CMD_PAGEPROG:
		info->use_ecc = (info->seqin_column >= mtd->writesize) ? 0 : 1;

		if (prepare_read_prog_cmd(info, cmdset->program,
				info->seqin_column, info->seqin_page_addr))
			break;

		pxa3xx_nand_do_cmd(info, NDSR_WRDREQ);
		break;
	case NAND_CMD_ERASE1:
		if (prepare_erase_cmd(info, cmdset->erase, page_addr))
			break;

		pxa3xx_nand_do_cmd(info, NDSR_CS0_BBD | NDSR_CS0_CMDD);
		break;
	case NAND_CMD_ERASE2:
		break;
	case NAND_CMD_READID:
	case NAND_CMD_STATUS:
		info->use_dma = 0;	/* force PIO read */
		info->buf_start = 0;
		info->buf_count = (command == NAND_CMD_READID) ?
				info->read_id_bytes : 1;

		if (prepare_other_cmd(info, (command == NAND_CMD_READID) ?
				cmdset->read_id : cmdset->read_status))
			break;

		pxa3xx_nand_do_cmd(info, NDSR_RDDREQ);
		break;
	case NAND_CMD_RESET:
		if (prepare_other_cmd(info, cmdset->reset))
			break;

		ret = pxa3xx_nand_do_cmd(info, NDSR_CS0_CMDD);
		if (ret == 0) {
			int timeout = 2;
			uint32_t ndcr;

			while (timeout--) {
				if (nand_readl(info, NDSR) & NDSR_RDY)
					break;
				msleep(10);
			}

			ndcr = nand_readl(info, NDCR);
			nand_writel(info, NDCR, ndcr & ~NDCR_ND_RUN);
		}
		break;
	default:
		printk(KERN_ERR "non-supported command.\n");
		break;
	}

	if (info->retcode == ERR_DBERR) {
		printk(KERN_ERR "double bit error @ page %08x\n", page_addr);
		info->retcode = ERR_NONE;
	}
}

static uint8_t pxa3xx_nand_read_byte(struct mtd_info *mtd)
{
	struct pxa3xx_nand_info *info = mtd->priv;
	char retval = 0xFF;

	if (info->buf_start < info->buf_count)
		/* Has just send a new command? */
		retval = info->data_buff[info->buf_start++];

	return retval;
}

static u16 pxa3xx_nand_read_word(struct mtd_info *mtd)
{
	struct pxa3xx_nand_info *info = mtd->priv;
	u16 retval = 0xFFFF;

	if (!(info->buf_start & 0x01) && info->buf_start < info->buf_count) {
		retval = *((u16 *)(info->data_buff+info->buf_start));
		info->buf_start += 2;
	}
	return retval;
}

static void pxa3xx_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
	struct pxa3xx_nand_info *info = mtd->priv;
	int real_len = min_t(size_t, len, info->buf_count - info->buf_start);

	memcpy(buf, info->data_buff + info->buf_start, real_len);
	info->buf_start += real_len;
}

static void pxa3xx_nand_write_buf(struct mtd_info *mtd,
		const uint8_t *buf, int len)
{
	struct pxa3xx_nand_info *info = mtd->priv;
	int real_len = min_t(size_t, len, info->buf_count - info->buf_start);

	memcpy(info->data_buff + info->buf_start, buf, real_len);
	info->buf_start += real_len;
}

static int pxa3xx_nand_verify_buf(struct mtd_info *mtd,
		const uint8_t *buf, int len)
{
	return 0;
}

static void pxa3xx_nand_select_chip(struct mtd_info *mtd, int chip)
{
	return;
}

static int pxa3xx_nand_waitfunc(struct mtd_info *mtd, struct nand_chip *this)
{
	struct pxa3xx_nand_info *info = mtd->priv;

	/* pxa3xx_nand_send_command has waited for command complete */
	if (this->state == FL_WRITING || this->state == FL_ERASING) {
		if (info->retcode == ERR_NONE)
			return 0;
		else {
			/*
			 * any error make it return 0x01 which will tell
			 * the caller the erase and write fail
			 */
			return 0x01;
		}
	}

	return 0;
}

static void pxa3xx_nand_ecc_hwctl(struct mtd_info *mtd, int mode)
{
	return;
}

static int pxa3xx_nand_ecc_calculate(struct mtd_info *mtd,
		const uint8_t *dat, uint8_t *ecc_code)
{
	return 0;
}

static int pxa3xx_nand_ecc_correct(struct mtd_info *mtd,
		uint8_t *dat, uint8_t *read_ecc, uint8_t *calc_ecc)
{
	struct pxa3xx_nand_info *info = mtd->priv;
	/*
	 * Any error include ERR_SEND_CMD, ERR_DBERR, ERR_BUSERR, we
	 * consider it as a ecc error which will tell the caller the
	 * read fail We have distinguish all the errors, but the
	 * nand_read_ecc only check this function return value
	 *
	 * Corrected (single-bit) errors must also be noted.
	 */
	if (info->retcode == ERR_SBERR)
		return 1;
	else if (info->retcode != ERR_NONE)
		return -1;

	return 0;
}

static int __readid(struct pxa3xx_nand_info *info, uint32_t *id)
{
	const struct pxa3xx_nand_flash *f = info->flash_info;
	const struct pxa3xx_nand_cmdset *cmdset = f->cmdset;
	uint32_t ndcr;
	uint8_t  id_buff[8];

	if (prepare_other_cmd(info, cmdset->read_id)) {
		printk(KERN_ERR "failed to prepare command\n");
		return -EINVAL;
	}

	/* Send command */
	if (write_cmd(info))
		goto fail_timeout;

	/* Wait for CMDDM(command done successfully) */
	if (wait_for_event(info, NDSR_RDDREQ))
		goto fail_timeout;

	__raw_readsl(info->mmio_base + NDDB, id_buff, 2);
	*id = id_buff[0] | (id_buff[1] << 8);
	return 0;

fail_timeout:
	ndcr = nand_readl(info, NDCR);
	nand_writel(info, NDCR, ndcr & ~NDCR_ND_RUN);
	udelay(10);
	return -ETIMEDOUT;
}

static int pxa3xx_nand_config_flash(struct pxa3xx_nand_info *info,
				    const struct pxa3xx_nand_flash *f)
{
	struct platform_device *pdev = info->pdev;
	struct pxa3xx_nand_platform_data *pdata = pdev->dev.platform_data;
	uint32_t ndcr = 0x00000FFF; /* disable all interrupts */

	if (f->page_size != 2048 && f->page_size != 512)
		return -EINVAL;

	if (f->flash_width != 16 && f->flash_width != 8)
		return -EINVAL;

	/* calculate flash information */
	info->oob_size = (f->page_size == 2048) ? 64 : 16;
	info->read_id_bytes = (f->page_size == 2048) ? 4 : 2;

	/* calculate addressing information */
	info->col_addr_cycles = (f->page_size == 2048) ? 2 : 1;

	if (f->num_blocks * f->page_per_block > 65536)
		info->row_addr_cycles = 3;
	else
		info->row_addr_cycles = 2;

	ndcr |= (pdata->enable_arbiter) ? NDCR_ND_ARB_EN : 0;
	ndcr |= (info->col_addr_cycles == 2) ? NDCR_RA_START : 0;
	ndcr |= (f->page_per_block == 64) ? NDCR_PG_PER_BLK : 0;
	ndcr |= (f->page_size == 2048) ? NDCR_PAGE_SZ : 0;
	ndcr |= (f->flash_width == 16) ? NDCR_DWIDTH_M : 0;
	ndcr |= (f->dfc_width == 16) ? NDCR_DWIDTH_C : 0;

	ndcr |= NDCR_RD_ID_CNT(info->read_id_bytes);
	ndcr |= NDCR_SPARE_EN; /* enable spare by default */

	info->reg_ndcr = ndcr;

	pxa3xx_nand_set_timing(info, f->timing);
	info->flash_info = f;
	return 0;
}

static void pxa3xx_nand_detect_timing(struct pxa3xx_nand_info *info,
				      struct pxa3xx_nand_timing *t)
{
	unsigned long nand_clk = clk_get_rate(info->clk);
	uint32_t ndtr0 = nand_readl(info, NDTR0CS0);
	uint32_t ndtr1 = nand_readl(info, NDTR1CS0);

	t->tCH = cycle2ns(tCH_NDTR0(ndtr0), nand_clk);
	t->tCS = cycle2ns(tCS_NDTR0(ndtr0), nand_clk);
	t->tWH = cycle2ns(tWH_NDTR0(ndtr0), nand_clk);
	t->tWP = cycle2ns(tWP_NDTR0(ndtr0), nand_clk);
	t->tRH = cycle2ns(tRH_NDTR0(ndtr0), nand_clk);
	t->tRP = cycle2ns(tRP_NDTR0(ndtr0), nand_clk);

	t->tR = cycle2ns(tR_NDTR1(ndtr1), nand_clk);
	t->tWHR = cycle2ns(tWHR_NDTR1(ndtr1), nand_clk);
	t->tAR = cycle2ns(tAR_NDTR1(ndtr1), nand_clk);
}

static int pxa3xx_nand_detect_config(struct pxa3xx_nand_info *info)
{
	uint32_t ndcr = nand_readl(info, NDCR);
	struct nand_flash_dev *type = NULL;
	uint32_t id = -1;
	int i;

	default_flash.page_per_block = ndcr & NDCR_PG_PER_BLK ? 64 : 32;
	default_flash.page_size = ndcr & NDCR_PAGE_SZ ? 2048 : 512;
	default_flash.flash_width = ndcr & NDCR_DWIDTH_M ? 16 : 8;
	default_flash.dfc_width = ndcr & NDCR_DWIDTH_C ? 16 : 8;

	if (default_flash.page_size == 2048)
		default_flash.cmdset = &largepage_cmdset;
	else
		default_flash.cmdset = &smallpage_cmdset;

	/* set info fields needed to __readid */
	info->flash_info = &default_flash;
	info->read_id_bytes = (default_flash.page_size == 2048) ? 4 : 2;
	info->reg_ndcr = ndcr;

	if (__readid(info, &id))
		return -ENODEV;

	/* Lookup the flash id */
	id = (id >> 8) & 0xff;		/* device id is byte 2 */
	for (i = 0; nand_flash_ids[i].name != NULL; i++) {
		if (id == nand_flash_ids[i].id) {
			type =  &nand_flash_ids[i];
			break;
		}
	}

	if (!type)
		return -ENODEV;

	/* fill the missing flash information */
	i = __ffs(default_flash.page_per_block * default_flash.page_size);
	default_flash.num_blocks = type->chipsize << (20 - i);

	info->oob_size = (default_flash.page_size == 2048) ? 64 : 16;

	/* calculate addressing information */
	info->col_addr_cycles = (default_flash.page_size == 2048) ? 2 : 1;

	if (default_flash.num_blocks * default_flash.page_per_block > 65536)
		info->row_addr_cycles = 3;
	else
		info->row_addr_cycles = 2;

	pxa3xx_nand_detect_timing(info, &default_timing);
	default_flash.timing = &default_timing;

	return 0;
}

static int pxa3xx_nand_detect_flash(struct pxa3xx_nand_info *info,
				    const struct pxa3xx_nand_platform_data *pdata)
{
	const struct pxa3xx_nand_flash *f;
	uint32_t id = -1;
	int i;

	if (pdata->keep_config)
		if (pxa3xx_nand_detect_config(info) == 0)
			return 0;

	for (i = 0; i<pdata->num_flash; ++i) {
		f = pdata->flash + i;

		if (pxa3xx_nand_config_flash(info, f))
			continue;

		if (__readid(info, &id))
			continue;

		if (id == f->chip_id)
			return 0;
	}

#ifdef CONFIG_MTD_NAND_PXA3xx_BUILTIN
	for (i = 0; i < ARRAY_SIZE(builtin_flash_types); i++) {

		f = builtin_flash_types[i];

		if (pxa3xx_nand_config_flash(info, f))
			continue;

		if (__readid(info, &id))
			continue;

		if (id == f->chip_id)
			return 0;
	}
#endif

	dev_warn(&info->pdev->dev,
		 "failed to detect configured nand flash; found %04x instead of\n",
		 id);
	return -ENODEV;
}

/* the maximum possible buffer size for large page with OOB data
 * is: 2048 + 64 = 2112 bytes, allocate a page here for both the
 * data buffer and the DMA descriptor
 */
#define MAX_BUFF_SIZE	PAGE_SIZE

static int pxa3xx_nand_init_buff(struct pxa3xx_nand_info *info)
{
	struct platform_device *pdev = info->pdev;
	int data_desc_offset = MAX_BUFF_SIZE - sizeof(struct pxa_dma_desc);

	if (use_dma == 0) {
		info->data_buff = kmalloc(MAX_BUFF_SIZE, GFP_KERNEL);
		if (info->data_buff == NULL)
			return -ENOMEM;
		return 0;
	}

	info->data_buff = dma_alloc_coherent(&pdev->dev, MAX_BUFF_SIZE,
				&info->data_buff_phys, GFP_KERNEL);
	if (info->data_buff == NULL) {
		dev_err(&pdev->dev, "failed to allocate dma buffer\n");
		return -ENOMEM;
	}

	info->data_buff_size = MAX_BUFF_SIZE;
	info->data_desc = (void *)info->data_buff + data_desc_offset;
	info->data_desc_addr = info->data_buff_phys + data_desc_offset;

	info->data_dma_ch = pxa_request_dma("nand-data", DMA_PRIO_LOW,
				pxa3xx_nand_data_dma_irq, info);
	if (info->data_dma_ch < 0) {
		dev_err(&pdev->dev, "failed to request data dma\n");
		dma_free_coherent(&pdev->dev, info->data_buff_size,
				info->data_buff, info->data_buff_phys);
		return info->data_dma_ch;
	}

	return 0;
}

static struct nand_ecclayout hw_smallpage_ecclayout = {
	.eccbytes = 6,
	.eccpos = {8, 9, 10, 11, 12, 13 },
	.oobfree = { {2, 6} }
};

static struct nand_ecclayout hw_largepage_ecclayout = {
	.eccbytes = 24,
	.eccpos = {
		40, 41, 42, 43, 44, 45, 46, 47,
		48, 49, 50, 51, 52, 53, 54, 55,
		56, 57, 58, 59, 60, 61, 62, 63},
	.oobfree = { {2, 38} }
};

static void pxa3xx_nand_init_mtd(struct mtd_info *mtd,
				 struct pxa3xx_nand_info *info)
{
	const struct pxa3xx_nand_flash *f = info->flash_info;
	struct nand_chip *this = &info->nand_chip;

	this->options = (f->flash_width == 16) ? NAND_BUSWIDTH_16: 0;

	this->waitfunc		= pxa3xx_nand_waitfunc;
	this->select_chip	= pxa3xx_nand_select_chip;
	this->dev_ready		= pxa3xx_nand_dev_ready;
	this->cmdfunc		= pxa3xx_nand_cmdfunc;
	this->read_word		= pxa3xx_nand_read_word;
	this->read_byte		= pxa3xx_nand_read_byte;
	this->read_buf		= pxa3xx_nand_read_buf;
	this->write_buf		= pxa3xx_nand_write_buf;
	this->verify_buf	= pxa3xx_nand_verify_buf;

	this->ecc.mode		= NAND_ECC_HW;
	this->ecc.hwctl		= pxa3xx_nand_ecc_hwctl;
	this->ecc.calculate	= pxa3xx_nand_ecc_calculate;
	this->ecc.correct	= pxa3xx_nand_ecc_correct;
	this->ecc.size		= f->page_size;

	if (f->page_size == 2048)
		this->ecc.layout = &hw_largepage_ecclayout;
	else
		this->ecc.layout = &hw_smallpage_ecclayout;

	this->chip_delay = 25;
}

static int pxa3xx_nand_probe(struct platform_device *pdev)
{
	struct pxa3xx_nand_platform_data *pdata;
	struct pxa3xx_nand_info *info;
	struct nand_chip *this;
	struct mtd_info *mtd;
	struct resource *r;
	int ret = 0, irq;

	pdata = pdev->dev.platform_data;

	if (!pdata) {
		dev_err(&pdev->dev, "no platform data defined\n");
		return -ENODEV;
	}

	mtd = kzalloc(sizeof(struct mtd_info) + sizeof(struct pxa3xx_nand_info),
			GFP_KERNEL);
	if (!mtd) {
		dev_err(&pdev->dev, "failed to allocate memory\n");
		return -ENOMEM;
	}

	info = (struct pxa3xx_nand_info *)(&mtd[1]);
	info->pdev = pdev;

	this = &info->nand_chip;
	mtd->priv = info;
	mtd->owner = THIS_MODULE;

	info->clk = clk_get(&pdev->dev, NULL);
	if (IS_ERR(info->clk)) {
		dev_err(&pdev->dev, "failed to get nand clock\n");
		ret = PTR_ERR(info->clk);
		goto fail_free_mtd;
	}
	clk_enable(info->clk);

	r = platform_get_resource(pdev, IORESOURCE_DMA, 0);
	if (r == NULL) {
		dev_err(&pdev->dev, "no resource defined for data DMA\n");
		ret = -ENXIO;
		goto fail_put_clk;
	}
	info->drcmr_dat = r->start;

	r = platform_get_resource(pdev, IORESOURCE_DMA, 1);
	if (r == NULL) {
		dev_err(&pdev->dev, "no resource defined for command DMA\n");
		ret = -ENXIO;
		goto fail_put_clk;
	}
	info->drcmr_cmd = r->start;

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		dev_err(&pdev->dev, "no IRQ resource defined\n");
		ret = -ENXIO;
		goto fail_put_clk;
	}

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (r == NULL) {
		dev_err(&pdev->dev, "no IO memory resource defined\n");
		ret = -ENODEV;
		goto fail_put_clk;
	}

	r = request_mem_region(r->start, resource_size(r), pdev->name);
	if (r == NULL) {
		dev_err(&pdev->dev, "failed to request memory resource\n");
		ret = -EBUSY;
		goto fail_put_clk;
	}

	info->mmio_base = ioremap(r->start, resource_size(r));
	if (info->mmio_base == NULL) {
		dev_err(&pdev->dev, "ioremap() failed\n");
		ret = -ENODEV;
		goto fail_free_res;
	}
	info->mmio_phys = r->start;

	ret = pxa3xx_nand_init_buff(info);
	if (ret)
		goto fail_free_io;

	/* initialize all interrupts to be disabled */
	disable_int(info, NDSR_MASK);

	ret = request_irq(irq, pxa3xx_nand_irq, IRQF_DISABLED,
			  pdev->name, info);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to request IRQ\n");
		goto fail_free_buf;
	}

	ret = pxa3xx_nand_detect_flash(info, pdata);
	if (ret) {
		dev_err(&pdev->dev, "failed to detect flash\n");
		ret = -ENODEV;
		goto fail_free_irq;
	}

	pxa3xx_nand_init_mtd(mtd, info);

	platform_set_drvdata(pdev, mtd);

	if (nand_scan(mtd, 1)) {
		dev_err(&pdev->dev, "failed to scan nand\n");
		ret = -ENXIO;
		goto fail_free_irq;
	}

	return add_mtd_partitions(mtd, pdata->parts, pdata->nr_parts);

fail_free_irq:
	free_irq(irq, info);
fail_free_buf:
	if (use_dma) {
		pxa_free_dma(info->data_dma_ch);
		dma_free_coherent(&pdev->dev, info->data_buff_size,
			info->data_buff, info->data_buff_phys);
	} else
		kfree(info->data_buff);
fail_free_io:
	iounmap(info->mmio_base);
fail_free_res:
	release_mem_region(r->start, resource_size(r));
fail_put_clk:
	clk_disable(info->clk);
	clk_put(info->clk);
fail_free_mtd:
	kfree(mtd);
	return ret;
}

static int pxa3xx_nand_remove(struct platform_device *pdev)
{
	struct mtd_info *mtd = platform_get_drvdata(pdev);
	struct pxa3xx_nand_info *info = mtd->priv;
	struct resource *r;
	int irq;

	platform_set_drvdata(pdev, NULL);

	del_mtd_device(mtd);
	del_mtd_partitions(mtd);
	irq = platform_get_irq(pdev, 0);
	if (irq >= 0)
		free_irq(irq, info);
	if (use_dma) {
		pxa_free_dma(info->data_dma_ch);
		dma_free_writecombine(&pdev->dev, info->data_buff_size,
				info->data_buff, info->data_buff_phys);
	} else
		kfree(info->data_buff);

	iounmap(info->mmio_base);
	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	release_mem_region(r->start, resource_size(r));

	clk_disable(info->clk);
	clk_put(info->clk);

	kfree(mtd);
	return 0;
}

#ifdef CONFIG_PM
static int pxa3xx_nand_suspend(struct platform_device *pdev, pm_message_t state)
{
	struct mtd_info *mtd = (struct mtd_info *)platform_get_drvdata(pdev);
	struct pxa3xx_nand_info *info = mtd->priv;

	if (info->state != STATE_READY) {
		dev_err(&pdev->dev, "driver busy, state = %d\n", info->state);
		return -EAGAIN;
	}

	return 0;
}

static int pxa3xx_nand_resume(struct platform_device *pdev)
{
	struct mtd_info *mtd = (struct mtd_info *)platform_get_drvdata(pdev);
	struct pxa3xx_nand_info *info = mtd->priv;

	clk_enable(info->clk);

	return pxa3xx_nand_config_flash(info, info->flash_info);
}
#else
#define pxa3xx_nand_suspend	NULL
#define pxa3xx_nand_resume	NULL
#endif

static struct platform_driver pxa3xx_nand_driver = {
	.driver = {
		.name	= "pxa3xx-nand",
	},
	.probe		= pxa3xx_nand_probe,
	.remove		= pxa3xx_nand_remove,
	.suspend	= pxa3xx_nand_suspend,
	.resume		= pxa3xx_nand_resume,
};

static int __init pxa3xx_nand_init(void)
{
	return platform_driver_register(&pxa3xx_nand_driver);
}
module_init(pxa3xx_nand_init);

static void __exit pxa3xx_nand_exit(void)
{
	platform_driver_unregister(&pxa3xx_nand_driver);
}
module_exit(pxa3xx_nand_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("PXA3xx NAND controller driver");