Patchwork [OneNAND] OTP support re-implementation 1/1

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Submitter Amul Saha
Date Aug. 31, 2009, 9:19 a.m.
Message ID <A32D4C31541C4D8B9BF6CB4D6EF4B5DC@sisodomain.com>
Download mbox | patch
Permalink /patch/32616/
State New
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Comments

Amul Saha - Aug. 31, 2009, 9:19 a.m.
What is OTP in OneNAND?
The device includes,
1. one block-sized OTP (One Time Programmable) area and
2. user-controlled 1st block OTP(Block 0)
that can be used to increase system security or to provide identification capabilities.

What is done?
In OneNAND, one block of the NAND Array is set aside as an OTP memory area, and 1st Block (Block 0)
can be used as OTP area.
This area, available to the user, can be configured and locked with secured user information.
The OTP block can be read, programmed and locked using the same operations as any other NAND Flash
Array
memory block. After issuing an OTP-Lock, OTP block cannot be erased. OTP block is fully-guaranteed
to be a valid block.

Why it is done? (Impact)
Locking the 1st Block OTP has the effect of a 'Write-protect' to guard against accidental
re-programming of data stored in the 1st block and OTP Block.

Which problem it solves?
OTP support is provided in the existing implementation of OneNAND/Flex-OneNAND driver, but it is not
working with OneNAND devices.
Have observed the following in current OTP OneNAND Implmentation,
1. DataSheet specific sequence to lock the OTP Area is not followed.
2. Certain functions are quiet generic to cope with OTP specific activity.
This patch re-implements OTP support for OneNAND device.

How it is done?
For all blocks, 8th word is available to the user.
However,in case of OTP Block, 8th word of sector 0, page 0 is reserved as OTP Locking Bit area.
Therefore, in case of OTP Block, user usage on this area is prohibited.
Condition specific values are entered in the 8th word, sector0, page 0 of the OTP block during the
process of issuing an OTP-Lock.
The possible conditions are:-
1. Only 1st Block Lock
2. Only OTP Block Lock
3. Lock both the 1st Block and the OTP Block

What Other feature additions have been done in this patch?
This patch adds feature for:-
1. Only 1st Block Lock
2. Lock both the 1st Block and the OTP Blocks

Re-implemented OTP support for OneNAND
Added following features to OneNAND
	1. Lock only 1st Block in OneNAND
	2. Lock BOTH 1st Block and OTP Block in OneNAND

Signed-off-by: Amul Kumar Saha <amul.saha@samsung.com>
---
 drivers/mtd/onenand/Kconfig        |   19 ++
 drivers/mtd/onenand/onenand_base.c |  291 +++++++++++++++++++++++++++++++++----
 include/linux/mtd/onenand.h        |    2
 3 files changed, 281 insertions(+), 31 deletions(-)
Kyungmin Park - Aug. 31, 2009, 9:34 a.m.
Hi,

@@ -2717,16 +2927,21 @@ static int onenand_otp_walk(struct mtd_info
*mtd, loff_t from, size_t len,
       if (density < ONENAND_DEVICE_DENSITY_512Mb)
               otp_pages = 20;
       else
-               otp_pages = 10;
+               otp_pages = 50;

Is it always 50 pages? Is it right? why I think it's 10. please check
the previous OneNAND spec.
At least the latest OneNAND spec say it's 50. flex or not.

> +       /*
> +        * Note: OTP lock operation
> +        *       OTP block : 0xXXFC                     XX 1111 1100
> +        *       1st block : 0xXXF3 (If chip support)   XX 1111 0011
> +        *       Both      : 0xXXF0 (If chip support)   XX 1111 0000
> +        */
> +       if (FLEXONENAND(this)) {
> +
> +#ifdef CONFIG_ONENAND_OTP_AREA
> +               buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xFC;
> +#elif defined(CONFIG_ONENAND_OTP_BLOCK0)
> +               buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xF3;
> +#elif defined(CONFIG_ONENAND_OTP_AREA_BLOCK0)
> +               buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xF0;
> +#endif /* ONENAND_OTP_AREA | ONENAND_OTP_BLOCK0 | ONENAND_OTP_AREA_BLOCK0 */
> +       } else {
> +
> +#ifdef CONFIG_ONENAND_OTP_AREA
> +               buf[ONENAND_OTP_LOCK_OFFSET] = 0xFC;
> +#elif defined(CONFIG_ONENAND_OTP_BLOCK0)
> +               buf[ONENAND_OTP_LOCK_OFFSET] = 0xF3;
> +#elif defined(CONFIG_ONENAND_OTP_AREA_BLOCK0)
> +               buf[ONENAND_OTP_LOCK_OFFSET] = 0xF0;
> +#endif /* ONENAND_OTP_AREA | ONENAND_OTP_BLOCK0 | ONENAND_OTP_AREA_BLOCK0 */
> +       }
> +

it's too much #ifdef, #endif. Introuduce the opt_lock_offset and set
the proper offset based on flex or not.

And the set the buf[otp_lock_offset] = proper value.

Thank you,
Kyungmin Park
Amul Saha - Sept. 2, 2009, 5:55 a.m.
>
> @@ -2717,16 +2927,21 @@ static int onenand_otp_walk(struct mtd_info
> *mtd, loff_t from, size_t len,
>       if (density < ONENAND_DEVICE_DENSITY_512Mb)
>               otp_pages = 20;
>       else
> -               otp_pages = 10;
> +               otp_pages = 50;
>
> Is it always 50 pages? Is it right? why I think it's 10. please check
> the previous OneNAND spec.
> At least the latest OneNAND spec say it's 50. flex or not.
>

I've checked different OneNAND specs and 50 pages have been allocated for the User Area in all of 
those.

>> +       if (FLEXONENAND(this)) {
>> +
>> +#ifdef CONFIG_ONENAND_OTP_AREA
>> +               buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xFC;
>> +#elif defined(CONFIG_ONENAND_OTP_BLOCK0)
>> +               buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xF3;
>> +#elif defined(CONFIG_ONENAND_OTP_AREA_BLOCK0)
>> +               buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xF0;
>> +#endif /* ONENAND_OTP_AREA | ONENAND_OTP_BLOCK0 | ONENAND_OTP_AREA_BLOCK0 */
>> +       } else {
>> +
>> +#ifdef CONFIG_ONENAND_OTP_AREA
>> +               buf[ONENAND_OTP_LOCK_OFFSET] = 0xFC;
>> +#elif defined(CONFIG_ONENAND_OTP_BLOCK0)
>> +               buf[ONENAND_OTP_LOCK_OFFSET] = 0xF3;
>> +#elif defined(CONFIG_ONENAND_OTP_AREA_BLOCK0)
>> +               buf[ONENAND_OTP_LOCK_OFFSET] = 0xF0;
>> +#endif /* ONENAND_OTP_AREA | ONENAND_OTP_BLOCK0 | ONENAND_OTP_AREA_BLOCK0 */
>> +       }
>> +
>
> it's too much #ifdef, #endif. Introuduce the opt_lock_offset and set
> the proper offset based on flex or not.
>
> And the set the buf[otp_lock_offset] = proper value.
>
Accepted and corrected.

Please find the patch in the following mail.

Regards,
Amul

Patch

diff --git a/drivers/mtd/onenand/Kconfig b/drivers/mtd/onenand/Kconfig
index 79fa79e..07ca80c 100644
--- a/drivers/mtd/onenand/Kconfig
+++ b/drivers/mtd/onenand/Kconfig
@@ -48,6 +48,25 @@  config MTD_ONENAND_OTP

 	  OTP block is fully-guaranteed to be a valid block.

+if MTD_ONENAND_OTP
+
+config ONENAND_OTP_AREA
+	bool "OTP area ONLY"
+	depends on MTD_ONENAND_OTP
+	select ON_OTP_AREA
+
+config ONENAND_OTP_BLOCK0
+	bool "Block[0] ONLY"
+	depends on MTD_ONENAND_OTP && !ONENAND_OTP_AREA
+	select ON_OTP_BLOCK0
+
+config ONENAND_OTP_AREA_BLOCK0
+	bool "BOTH OTP area AND Block[0]"
+	depends on MTD_ONENAND_OTP && !ONENAND_OTP_AREA && !ONENAND_OTP_BLOCK0
+	select ON_OTP_AREA_BLOCK0
+
+endif #MTD_ONENAND_OTP
+
 config MTD_ONENAND_2X_PROGRAM
 	bool "OneNAND 2X program support"
 	help
diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index 6e82909..7c4fb75 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -13,6 +13,10 @@ 
  *	Flex-OneNAND support
  *	Copyright (C) Samsung Electronics, 2008
  *
+ *	Amul Kumar Saha <amul.saha@samsung.com>
+ *	OTP support
+ *	Copyright (C) SAMSUNG Electronics, 2009
+ *
  * 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.
@@ -308,6 +312,81 @@  int flexonenand_region(struct mtd_info *mtd, loff_t addr)
 EXPORT_SYMBOL(flexonenand_region);

 /**
+ * onenand_otp_command - Send OTP specific command to OneNAND device
+ * @param mtd	 MTD device structure
+ * @param cmd	 the command to be sent
+ * @param addr	 offset to read from or write to
+ * @param len	 number of bytes to read or write
+ */
+static int onenand_otp_command(struct mtd_info *mtd, int cmd, loff_t addr,
+				size_t len)
+{
+	struct onenand_chip *this = mtd->priv;
+	int value, block, page;
+
+	/* Address translation */
+	switch (cmd) {
+	case ONENAND_CMD_OTP_ACCESS:
+		block = (int) (addr >> this->erase_shift);
+		page = -1;
+		break;
+
+	default:
+		block = (int) (addr >> this->erase_shift);
+		page = (int) (addr >> this->page_shift);
+
+		if (ONENAND_IS_2PLANE(this)) {
+			/* Make the even block number */
+			block &= ~1;
+			/* Is it the odd plane? */
+			if (addr & this->writesize)
+				block++;
+			page >>= 1;
+		}
+		page &= this->page_mask;
+		break;
+	}
+
+	if (block != -1) {
+		/* Write 'DFS, FBA' of Flash */
+		value = onenand_block_address(this, block);
+		this->write_word(value, this->base +
+				ONENAND_REG_START_ADDRESS1);
+	}
+
+	if (page != -1) {
+		/* Now we use page size operation */
+		int sectors = 4, count = 4;
+		int dataram;
+
+		switch (cmd) {
+		default:
+			if (ONENAND_IS_2PLANE(this) && cmd == ONENAND_CMD_PROG)
+				cmd = ONENAND_CMD_2X_PROG;
+			dataram = ONENAND_CURRENT_BUFFERRAM(this);
+			break;
+		}
+
+		/* Write 'FPA, FSA' of Flash */
+		value = onenand_page_address(page, sectors);
+		this->write_word(value, this->base +
+				ONENAND_REG_START_ADDRESS8);
+
+		/* Write 'BSA, BSC' of DataRAM */
+		value = onenand_buffer_address(dataram, sectors, count);
+		this->write_word(value, this->base + ONENAND_REG_START_BUFFER);
+	}
+
+	/* Interrupt clear */
+	this->write_word(ONENAND_INT_CLEAR, this->base + ONENAND_REG_INTERRUPT);
+
+	/* Write command */
+	this->write_word(cmd, this->base + ONENAND_REG_COMMAND);
+
+	return 0;
+}
+
+/**
  * onenand_command - [DEFAULT] Send command to OneNAND device
  * @param mtd		MTD device structure
  * @param cmd		the command to be sent
@@ -1879,7 +1958,8 @@  static int onenand_write_ops_nolock(struct mtd_info *mtd, loff_t to,
 			onenand_update_bufferram(mtd, prev, !ret && !prev_subpage);
 			if (ret) {
 				written -= prevlen;
-				printk(KERN_ERR "onenand_write_ops_nolock: write filaed %d\n", ret);
+				printk(KERN_ERR "onenand_write_ops_nolock: \
+						write failed %d\n", ret);
 				break;
 			}

@@ -1905,14 +1985,16 @@  static int onenand_write_ops_nolock(struct mtd_info *mtd, loff_t to,
 			/* In partial page write we don't update bufferram */
 			onenand_update_bufferram(mtd, to, !ret && !subpage);
 			if (ret) {
-				printk(KERN_ERR "onenand_write_ops_nolock: write filaed %d\n", ret);
+				printk(KERN_ERR "onenand_write_ops_nolock: \
+						write failed %d\n", ret);
 				break;
 			}

 			/* Only check verify write turn on */
 			ret = onenand_verify(mtd, buf, to, thislen);
 			if (ret) {
-				printk(KERN_ERR "onenand_write_ops_nolock: verify failed %d\n", ret);
+				printk(KERN_ERR "onenand_write_ops_nolock: \
+						verify failed %d\n", ret);
 				break;
 			}

@@ -1945,6 +2027,134 @@  static int onenand_write_ops_nolock(struct mtd_info *mtd, loff_t to,


 /**
+ * onenand_otp_write_oob_nolock - [Internal] OneNAND write out-of-band, specific to OTP
+ * @param mtd		MTD device structure
+ * @param to		offset to write to
+ * @param len		number of bytes to write
+ * @param retlen	pointer to variable to store the number of written bytes
+ * @param buf		the data to write
+ *
+ * OneNAND write out-of-band only for OTP
+ */
+static int onenand_otp_write_oob_nolock(struct mtd_info *mtd, loff_t to,
+				    struct mtd_oob_ops *ops)
+{
+	struct onenand_chip *this = mtd->priv;
+	int column, ret = 0, oobsize;
+	int written = 0;
+	u_char *oobbuf;
+	size_t len = ops->ooblen;
+	const u_char *buf = ops->oobbuf;
+	int block, value, status;
+
+	to += ops->ooboffs;
+
+	/* Initialize retlen, in case of early exit */
+	ops->oobretlen = 0;
+
+	oobsize = mtd->oobsize;
+
+	column = to & (mtd->oobsize - 1);
+
+	oobbuf = this->oob_buf;
+
+	/* Loop until all data write */
+	while (written < len) {
+		int thislen = min_t(int, oobsize, len - written);
+
+		cond_resched();
+
+		block = (int) (to >> this->erase_shift);
+		/*
+		 * Write 'DFS, FBA' of Flash
+		 * Add: F100h DQ=DFS, FBA
+		 */
+
+		value = onenand_block_address(this, block);
+		this->write_word(value, this->base +
+				ONENAND_REG_START_ADDRESS1);
+
+		/*
+		 * Select DataRAM for DDP
+		 * Add: F101h DQ=DBS
+		 */
+
+		value = onenand_bufferram_address(this, block);
+		this->write_word(value, this->base +
+				ONENAND_REG_START_ADDRESS2);
+		ONENAND_SET_NEXT_BUFFERRAM(this);
+
+		/*
+		 * Enter OTP access mode
+		 */
+		this->command(mtd, ONENAND_CMD_OTP_ACCESS, 0, 0);
+		this->wait(mtd, FL_OTPING);
+
+		/* We send data to spare ram with oobsize
+		 * to prevent byte access */
+		memcpy(oobbuf + column, buf, thislen);
+
+		/*
+		 * Write Data into DataRAM
+		 * Add: 8th Word
+		 * in sector0/spare/page0
+		 * DQ=XXFCh
+		 */
+		this->write_bufferram(mtd, ONENAND_SPARERAM,
+					oobbuf, 0, mtd->oobsize);
+
+		onenand_otp_command(mtd, ONENAND_CMD_PROGOOB, to, mtd->oobsize);
+		onenand_update_bufferram(mtd, to, 0);
+		if (ONENAND_IS_2PLANE(this)) {
+			ONENAND_SET_BUFFERRAM1(this);
+			onenand_update_bufferram(mtd, to + this->writesize, 0);
+		}
+
+		ret = this->wait(mtd, FL_WRITING);
+		if (ret) {
+			printk(KERN_ERR "onenand_write_oob_nolock: \
+					write failed %d\n", ret);
+			break;
+		}
+
+		/* Exit OTP access mode */
+		this->command(mtd, ONENAND_CMD_RESET, 0, 0);
+		this->wait(mtd, FL_RESETING);
+
+		status = this->read_word(this->base + ONENAND_REG_CTRL_STATUS);
+		status &= 0x60;
+
+		if (status == 0x60) {
+			printk(KERN_DEBUG "\nBLOCK\tSTATUS\n");
+			printk(KERN_DEBUG "1st Block\tLOCKED\n");
+			printk(KERN_DEBUG "OTP Block\tLOCKED\n");
+		} else if (status == 0x20) {
+			printk(KERN_DEBUG "\nBLOCK\tSTATUS\n");
+			printk(KERN_DEBUG "1st Block\tLOCKED\n");
+			printk(KERN_DEBUG "OTP Block\tUN-LOCKED\n");
+		} else if (status == 0x40) {
+			printk(KERN_DEBUG "\nBLOCK\tSTATUS\n");
+			printk(KERN_DEBUG "1st Block\tUN-LOCKED\n");
+			printk(KERN_DEBUG "OTP Block\tLOCKED\n");
+		} else {
+			printk(KERN_DEBUG "Reboot to check\n");
+		}
+
+		written += thislen;
+		if (written == len)
+			break;
+
+		to += mtd->writesize;
+		buf += thislen;
+		column = 0;
+	}
+
+	ops->oobretlen = written;
+
+	return ret;
+}
+
+/**
  * onenand_write_oob_nolock - [Internal] OneNAND write out-of-band
  * @param mtd		MTD device structure
  * @param to		offset to write to
@@ -2659,11 +2869,11 @@  static int do_otp_lock(struct mtd_info *mtd, loff_t from, size_t len,
 	struct mtd_oob_ops ops;
 	int ret;

-	/* Enter OTP access mode */
-	this->command(mtd, ONENAND_CMD_OTP_ACCESS, 0, 0);
-	this->wait(mtd, FL_OTPING);
-
 	if (FLEXONENAND(this)) {
+
+		/* Enter OTP access mode */
+		this->command(mtd, ONENAND_CMD_OTP_ACCESS, 0, 0);
+		this->wait(mtd, FL_OTPING);
 		/*
 		 * For Flex-OneNAND, we write lock mark to 1st word of sector 4 of
 		 * main area of page 49.
@@ -2674,19 +2884,19 @@  static int do_otp_lock(struct mtd_info *mtd, loff_t from, size_t len,
 		ops.oobbuf = NULL;
 		ret = onenand_write_ops_nolock(mtd, mtd->writesize * 49, &ops);
 		*retlen = ops.retlen;
+
+		/* Exit OTP access mode */
+		this->command(mtd, ONENAND_CMD_RESET, 0, 0);
+		this->wait(mtd, FL_RESETING);
 	} else {
 		ops.mode = MTD_OOB_PLACE;
 		ops.ooblen = len;
 		ops.oobbuf = buf;
 		ops.ooboffs = 0;
-		ret = onenand_write_oob_nolock(mtd, from, &ops);
+		ret = onenand_otp_write_oob_nolock(mtd, from, &ops);
 		*retlen = ops.oobretlen;
 	}

-	/* Exit OTP access mode */
-	this->command(mtd, ONENAND_CMD_RESET, 0, 0);
-	this->wait(mtd, FL_RESETING);
-
 	return ret;
 }

@@ -2717,16 +2927,21 @@  static int onenand_otp_walk(struct mtd_info *mtd, loff_t from, size_t len,
 	if (density < ONENAND_DEVICE_DENSITY_512Mb)
 		otp_pages = 20;
 	else
-		otp_pages = 10;
+		otp_pages = 50;

 	if (mode == MTD_OTP_FACTORY) {
 		from += mtd->writesize * otp_pages;
-		otp_pages = 64 - otp_pages;
+		otp_pages = ONENAND_PAGES_PER_BLOCK - otp_pages;
 	}

 	/* Check User/Factory boundary */
-	if (((mtd->writesize * otp_pages) - (from + len)) < 0)
-		return 0;
+	if (mode == MTD_OTP_USER) {
+		if (((mtd->writesize * otp_pages) - (from + len)) < 0)
+			return 0;
+	} else {
+		if (((mtd->writesize * otp_pages) - len) < 0)
+			return 0;
+	}

 	onenand_get_device(mtd, FL_OTPING);
 	while (len > 0 && otp_pages > 0) {
@@ -2749,13 +2964,12 @@  static int onenand_otp_walk(struct mtd_info *mtd, loff_t from, size_t len,
 			*retlen += sizeof(struct otp_info);
 		} else {
 			size_t tmp_retlen;
-			int size = len;

 			ret = action(mtd, from, len, &tmp_retlen, buf);

-			buf += size;
-			len -= size;
-			*retlen += size;
+			buf += tmp_retlen;
+			len -= tmp_retlen;
+			*retlen += tmp_retlen;

 			if (ret)
 				break;
@@ -2872,17 +3086,6 @@  static int onenand_lock_user_prot_reg(struct mtd_info *mtd, loff_t from,
 	memset(buf, 0xff, FLEXONENAND(this) ? this->writesize
 						 : mtd->oobsize);
 	/*
-	 * Note: OTP lock operation
-	 *       OTP block : 0xXXFC
-	 *       1st block : 0xXXF3 (If chip support)
-	 *       Both      : 0xXXF0 (If chip support)
-	 */
-	if (FLEXONENAND(this))
-		buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xFC;
-	else
-		buf[ONENAND_OTP_LOCK_OFFSET] = 0xFC;
-
-	/*
 	 * Write lock mark to 8th word of sector0 of page0 of the spare0.
 	 * We write 16 bytes spare area instead of 2 bytes.
 	 * For Flex-OneNAND, we write lock mark to 1st word of sector 4 of
@@ -2892,6 +3095,32 @@  static int onenand_lock_user_prot_reg(struct mtd_info *mtd, loff_t from,
 	from = 0;
 	len = FLEXONENAND(this) ? mtd->writesize : 16;

+	/*
+	 * Note: OTP lock operation
+	 *       OTP block : 0xXXFC			XX 1111 1100
+	 *       1st block : 0xXXF3 (If chip support)	XX 1111 0011
+	 *       Both      : 0xXXF0 (If chip support)	XX 1111 0000
+	 */
+	if (FLEXONENAND(this)) {
+
+#ifdef CONFIG_ONENAND_OTP_AREA
+		buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xFC;
+#elif defined(CONFIG_ONENAND_OTP_BLOCK0)
+		buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xF3;
+#elif defined(CONFIG_ONENAND_OTP_AREA_BLOCK0)
+		buf[FLEXONENAND_OTP_LOCK_OFFSET] = 0xF0;
+#endif	/* ONENAND_OTP_AREA | ONENAND_OTP_BLOCK0 | ONENAND_OTP_AREA_BLOCK0 */
+	} else {
+
+#ifdef CONFIG_ONENAND_OTP_AREA
+		buf[ONENAND_OTP_LOCK_OFFSET] = 0xFC;
+#elif defined(CONFIG_ONENAND_OTP_BLOCK0)
+		buf[ONENAND_OTP_LOCK_OFFSET] = 0xF3;
+#elif defined(CONFIG_ONENAND_OTP_AREA_BLOCK0)
+		buf[ONENAND_OTP_LOCK_OFFSET] = 0xF0;
+#endif	/* ONENAND_OTP_AREA | ONENAND_OTP_BLOCK0 | ONENAND_OTP_AREA_BLOCK0 */
+	}
+
 	ret = onenand_otp_walk(mtd, from, len, &retlen, buf, do_otp_lock, MTD_OTP_USER);

 	return ret ? : retlen;
diff --git a/include/linux/mtd/onenand.h b/include/linux/mtd/onenand.h
index 8ed8733..7bd1512 100644
--- a/include/linux/mtd/onenand.h
+++ b/include/linux/mtd/onenand.h
@@ -152,6 +152,8 @@  struct onenand_chip {
 /*
  * Helper macros
  */
+#define ONENAND_PAGES_PER_BLOCK        (1<<6)
+
 #define ONENAND_CURRENT_BUFFERRAM(this)		(this->bufferram_index)
 #define ONENAND_NEXT_BUFFERRAM(this)		(this->bufferram_index ^ 1)
 #define ONENAND_SET_NEXT_BUFFERRAM(this)	(this->bufferram_index ^= 1)