/*
 * nand_read.c: Simple NAND read functions for booting from NAND
 *
 * This is used by cpu/arm920/start.S assembler code,
 * and the board-specific linker script must make sure this
 * file is linked within the first 4kB of NAND flash.
 *
 * Taken from GPLv2 licensed vivi bootloader,
 * Copyright (C) 2002 MIZI Research, Inc.
 *
 * Author: Hwang, Chideok <hwang@mizi.com>
 * Date  : $Date: 2004/02/04 10:37:37 $
 *
 * u-boot integration and bad-block skipping (C) 2006 by OpenMoko, Inc.
 * Author: Harald Welte <laforge@openmoko.org>
 */

/* NOTE this stuff runs in steppingstone context! */

/* the API refers to 512-byte blocks */

#include <qi.h>
#include "nand_read.h"

#define NAND_CMD_READ0 0
#define NAND_CMD_READSTART 0x30

#define __REGb(x)	(*(volatile unsigned char *)(x))
#define __REGw(x)	(*(volatile unsigned short *)(x))
#define __REGi(x)	(*(volatile unsigned int *)(x))
#define NF_BASE		0x4e000000
#define NFCONF		__REGi(NF_BASE + 0x0)
#define NFCONT		__REGi(NF_BASE + 0x4)
#define NFCMD		__REGb(NF_BASE + 0x8)
#define NFADDR		__REGb(NF_BASE + 0xc)
#define NFDATA		__REGb(NF_BASE + 0x10)
#define NFDATA16	__REGw(NF_BASE + 0x10)
#define NFSTAT		__REGb(NF_BASE + 0x20)
#define NFSTAT_BUSY	1
#define nand_select()	(NFCONT &= ~(1 << 1))
#define nand_deselect()	(NFCONT |= (1 << 1))
#define nand_clear_RnB()	(NFSTAT |= (1 << 2))

static inline void nand_wait(void)
{
	int i;

	while (!(NFSTAT & NFSTAT_BUSY))
		for (i=0; i<10; i++);
}

/* configuration for 2440 with 2048byte sized flash */
#define NAND_5_ADDR_CYCLE
#define NAND_PAGE_SIZE		2048
#define BAD_BLOCK_OFFSET	NAND_PAGE_SIZE
#define	NAND_BLOCK_MASK		(NAND_PAGE_SIZE - 1)
#define NAND_BLOCK_SIZE		(NAND_PAGE_SIZE * 64)

int s3c2442_nand_is_bad_block(unsigned long block_index)
{
	unsigned char data;
	unsigned long page_num;

	nand_select();
	nand_clear_RnB();
	page_num = block_index >> 2; /* addr / 2048 */
	NFCMD = NAND_CMD_READ0;
	NFADDR = BAD_BLOCK_OFFSET & 0xff;
	NFADDR = (BAD_BLOCK_OFFSET >> 8) & 0xff;
	NFADDR = page_num & 0xff;
	NFADDR = (page_num >> 8) & 0xff;
	NFADDR = (page_num >> 16) & 0xff;
	NFCMD = NAND_CMD_READSTART;
	nand_wait();
	data = (NFDATA & 0xff);

	if (data != 0xff)
		return 1;

	return 0;
}

static int nand_read_page_ll(unsigned char *buf, unsigned long block512, int blocks512)
{
	unsigned short *ptr16 = (unsigned short *)buf;
	unsigned int i, page_num;
	unsigned int block_amount;
	int blocks_possible = (3 - (block512 & 3)) + 1;


	if (blocks512 > blocks_possible)
		blocks512 = blocks_possible;

	block_amount = (NAND_PAGE_SIZE / 4 / 2) * blocks512;

	nand_clear_RnB();

	NFCMD = NAND_CMD_READ0;

	page_num = block512 >> 2; /* 512 block -> 2048 block */
	/* Write Address */
	NFADDR = 0;
	NFADDR = (block512 & 3) << 1; /* which 512 block in 2048 */
	NFADDR = page_num & 0xff;
	NFADDR = (page_num >> 8) & 0xff;
	NFADDR = (page_num >> 16) & 0xff;
	NFCMD = NAND_CMD_READSTART;
	nand_wait();

	for (i = 0; i < block_amount; i++)
		*ptr16++ = NFDATA16;

	return blocks512;
}


/* low level nand read function */
int nand_read_ll(unsigned char *buf, unsigned long start_block512,
								  int blocks512)
{
	int i, j;

	/* chip Enable */
	nand_select();
	nand_clear_RnB();

	for (i = 0; i < 10; i++)
		;

	while (blocks512 > 0) {
		if (s3c2442_nand_is_bad_block(start_block512)) {
			start_block512 += 4;
			if (start_block512 >> 2 > BAD_BLOCK_OFFSET)
				/* end of NAND */
				return -1;
			continue;
		}

		j = nand_read_page_ll(buf, start_block512, blocks512);
		start_block512 += j;
		buf += j << 9;
		blocks512 -= j;

		if (this_board->get_ui_keys)
			if ((this_board->get_ui_keys)() & UI_ACTION_SKIPKERNEL) {
				puts(" ** skipping \n");
				return -3;
			}
	}

	/* chip Disable */
	nand_deselect();

	return 0;
}