Signed-off-by: Charles Manning <cdhmanning@xxxxxxxxx>
---
fs/yaffs2/yaffs_checkptrw.c | 420 +++++++++++++++++++++++++++++++++++++++++++
fs/yaffs2/yaffs_checkptrw.h | 33 ++++
fs/yaffs2/yaffs_ecc.c | 298 ++++++++++++++++++++++++++++++
fs/yaffs2/yaffs_ecc.h | 44 +++++
4 files changed, 795 insertions(+), 0 deletions(-)
create mode 100644 fs/yaffs2/yaffs_checkptrw.c
create mode 100644 fs/yaffs2/yaffs_checkptrw.h
create mode 100644 fs/yaffs2/yaffs_ecc.c
create mode 100644 fs/yaffs2/yaffs_ecc.h
diff --git a/fs/yaffs2/yaffs_checkptrw.c b/fs/yaffs2/yaffs_checkptrw.c
new file mode 100644
index 0000000..02b8ce6
--- /dev/null
+++ b/fs/yaffs2/yaffs_checkptrw.c
@@ -0,0 +1,420 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ * for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@xxxxxxxxxxxx>
+ *
+ * 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 "yaffs_checkptrw.h"
+#include "yaffs_getblockinfo.h"
+
+static int yaffs2_checkpt_space_ok(struct yaffs_dev *dev)
+{
+ int blocks_avail = dev->n_erased_blocks - dev->param.n_reserved_blocks;
+
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR("checkpt blocks available = %d" TENDSTR), blocks_avail));
+
+ return (blocks_avail <= 0) ? 0 : 1;
+}
+
+static int yaffs_checkpt_erase(struct yaffs_dev *dev)
+{
+ int i;
+
+ if (!dev->param.erase_fn)
+ return 0;
+ T(YAFFS_TRACE_CHECKPOINT, (TSTR("checking blocks %d to %d" TENDSTR),
+ dev->internal_start_block,
+ dev->internal_end_block));
+
+ for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
+ struct yaffs_block_info *bi = yaffs_get_block_info(dev, i);
+ if (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT) {
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR("erasing checkpt block %d" TENDSTR), i));
+
+ dev->n_erasures++;
+
+ if (dev->param.
+ erase_fn(dev,
+ i - dev->block_offset /* realign */ )) {
+ bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
+ dev->n_erased_blocks++;
+ dev->n_free_chunks +=
+ dev->param.chunks_per_block;
+ } else {
+ dev->param.bad_block_fn(dev, i);
+ bi->block_state = YAFFS_BLOCK_STATE_DEAD;
+ }
+ }
+ }
+
+ dev->blocks_in_checkpt = 0;
+
+ return 1;
+}
+
+static void yaffs2_checkpt_find_erased_block(struct yaffs_dev *dev)
+{
+ int i;
+ int blocks_avail = dev->n_erased_blocks - dev->param.n_reserved_blocks;
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR
+ ("allocating checkpt block: erased %d reserved %d avail %d next %d "
+ TENDSTR), dev->n_erased_blocks, dev->param.n_reserved_blocks,
+ blocks_avail, dev->checkpt_next_block));
+
+ if (dev->checkpt_next_block >= 0 &&
+ dev->checkpt_next_block <= dev->internal_end_block &&
+ blocks_avail > 0) {
+
+ for (i = dev->checkpt_next_block; i <= dev->internal_end_block;
+ i++) {
+ struct yaffs_block_info *bi =
+ yaffs_get_block_info(dev, i);
+ if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
+ dev->checkpt_next_block = i + 1;
+ dev->checkpt_cur_block = i;
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR("allocating checkpt block %d" TENDSTR),
+ i));
+ return;
+ }
+ }
+ }
+ T(YAFFS_TRACE_CHECKPOINT, (TSTR("out of checkpt blocks" TENDSTR)));
+
+ dev->checkpt_next_block = -1;
+ dev->checkpt_cur_block = -1;
+}
+
+static void yaffs2_checkpt_find_block(struct yaffs_dev *dev)
+{
+ int i;
+ struct yaffs_ext_tags tags;
+
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR("find next checkpt block: start: blocks %d next %d" TENDSTR),
+ dev->blocks_in_checkpt, dev->checkpt_next_block));
+
+ if (dev->blocks_in_checkpt < dev->checkpt_max_blocks)
+ for (i = dev->checkpt_next_block; i <= dev->internal_end_block;
+ i++) {
+ int chunk = i * dev->param.chunks_per_block;
+ int realigned_chunk = chunk - dev->chunk_offset;
+
+ dev->param.read_chunk_tags_fn(dev, realigned_chunk,
+ NULL, &tags);
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR
+ ("find next checkpt block: search: block %d oid %d seq %d eccr %d"
+ TENDSTR), i, tags.obj_id, tags.seq_number,
+ tags.ecc_result));
+
+ if (tags.seq_number == YAFFS_SEQUENCE_CHECKPOINT_DATA) {
+ /* Right kind of block */
+ dev->checkpt_next_block = tags.obj_id;
+ dev->checkpt_cur_block = i;
+ dev->checkpt_block_list[dev->
+ blocks_in_checkpt] = i;
+ dev->blocks_in_checkpt++;
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR("found checkpt block %d" TENDSTR), i));
+ return;
+ }
+ }
+
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR("found no more checkpt blocks" TENDSTR)));
+
+ dev->checkpt_next_block = -1;
+ dev->checkpt_cur_block = -1;
+}
+
+int yaffs2_checkpt_open(struct yaffs_dev *dev, int writing)
+{
+
+ dev->checkpt_open_write = writing;
+
+ /* Got the functions we need? */
+ if (!dev->param.write_chunk_tags_fn ||
+ !dev->param.read_chunk_tags_fn ||
+ !dev->param.erase_fn || !dev->param.bad_block_fn)
+ return 0;
+
+ if (writing && !yaffs2_checkpt_space_ok(dev))
+ return 0;
+
+ if (!dev->checkpt_buffer)
+ dev->checkpt_buffer =
+ YMALLOC_DMA(dev->param.total_bytes_per_chunk);
+ if (!dev->checkpt_buffer)
+ return 0;
+
+ dev->checkpt_page_seq = 0;
+ dev->checkpt_byte_count = 0;
+ dev->checkpt_sum = 0;
+ dev->checkpt_xor = 0;
+ dev->checkpt_cur_block = -1;
+ dev->checkpt_cur_chunk = -1;
+ dev->checkpt_next_block = dev->internal_start_block;
+
+ /* Erase all the blocks in the checkpoint area */
+ if (writing) {
+ memset(dev->checkpt_buffer, 0, dev->data_bytes_per_chunk);
+ dev->checkpt_byte_offs = 0;
+ return yaffs_checkpt_erase(dev);
+ } else {
+ int i;
+ /* Set to a value that will kick off a read */
+ dev->checkpt_byte_offs = dev->data_bytes_per_chunk;
+ /* A checkpoint block list of 1 checkpoint block per 16 block is (hopefully)
+ * going to be way more than we need */
+ dev->blocks_in_checkpt = 0;
+ dev->checkpt_max_blocks =
+ (dev->internal_end_block - dev->internal_start_block) / 16 +
+ 2;
+ dev->checkpt_block_list =
+ YMALLOC(sizeof(int) * dev->checkpt_max_blocks);
+ if (!dev->checkpt_block_list)
+ return 0;
+
+ for (i = 0; i < dev->checkpt_max_blocks; i++)
+ dev->checkpt_block_list[i] = -1;
+ }
+
+ return 1;
+}
+
+int yaffs2_get_checkpt_sum(struct yaffs_dev *dev, u32 * sum)
+{
+ u32 composite_sum;
+ composite_sum = (dev->checkpt_sum << 8) | (dev->checkpt_xor & 0xFF);
+ *sum = composite_sum;
+ return 1;
+}
+
+static int yaffs2_checkpt_flush_buffer(struct yaffs_dev *dev)
+{
+ int chunk;
+ int realigned_chunk;
+
+ struct yaffs_ext_tags tags;
+
+ if (dev->checkpt_cur_block < 0) {
+ yaffs2_checkpt_find_erased_block(dev);
+ dev->checkpt_cur_chunk = 0;
+ }
+
+ if (dev->checkpt_cur_block < 0)
+ return 0;
+
+ tags.is_deleted = 0;
+ tags.obj_id = dev->checkpt_next_block; /* Hint to next place to look */
+ tags.chunk_id = dev->checkpt_page_seq + 1;
+ tags.seq_number = YAFFS_SEQUENCE_CHECKPOINT_DATA;
+ tags.n_bytes = dev->data_bytes_per_chunk;
+ if (dev->checkpt_cur_chunk == 0) {
+ /* First chunk we write for the block? Set block state to
+ checkpoint */
+ struct yaffs_block_info *bi =
+ yaffs_get_block_info(dev, dev->checkpt_cur_block);
+ bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
+ dev->blocks_in_checkpt++;
+ }
+
+ chunk =
+ dev->checkpt_cur_block * dev->param.chunks_per_block +
+ dev->checkpt_cur_chunk;
+
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR
+ ("checkpoint wite buffer nand %d(%d:%d) objid %d chId %d" TENDSTR),
+ chunk, dev->checkpt_cur_block, dev->checkpt_cur_chunk, tags.obj_id,
+ tags.chunk_id));
+
+ realigned_chunk = chunk - dev->chunk_offset;
+
+ dev->n_page_writes++;
+
+ dev->param.write_chunk_tags_fn(dev, realigned_chunk,
+ dev->checkpt_buffer, &tags);
+ dev->checkpt_byte_offs = 0;
+ dev->checkpt_page_seq++;
+ dev->checkpt_cur_chunk++;
+ if (dev->checkpt_cur_chunk >= dev->param.chunks_per_block) {
+ dev->checkpt_cur_chunk = 0;
+ dev->checkpt_cur_block = -1;
+ }
+ memset(dev->checkpt_buffer, 0, dev->data_bytes_per_chunk);
+
+ return 1;
+}
+
+int yaffs2_checkpt_wr(struct yaffs_dev *dev, const void *data, int n_bytes)
+{
+ int i = 0;
+ int ok = 1;
+
+ u8 *data_bytes = (u8 *) data;
+
+ if (!dev->checkpt_buffer)
+ return 0;
+
+ if (!dev->checkpt_open_write)
+ return -1;
+
+ while (i < n_bytes && ok) {
+ dev->checkpt_buffer[dev->checkpt_byte_offs] = *data_bytes;
+ dev->checkpt_sum += *data_bytes;
+ dev->checkpt_xor ^= *data_bytes;
+
+ dev->checkpt_byte_offs++;
+ i++;
+ data_bytes++;
+ dev->checkpt_byte_count++;
+
+ if (dev->checkpt_byte_offs < 0 ||
+ dev->checkpt_byte_offs >= dev->data_bytes_per_chunk)
+ ok = yaffs2_checkpt_flush_buffer(dev);
+ }
+
+ return i;
+}
+
+int yaffs2_checkpt_rd(struct yaffs_dev *dev, void *data, int n_bytes)
+{
+ int i = 0;
+ int ok = 1;
+ struct yaffs_ext_tags tags;
+
+ int chunk;
+ int realigned_chunk;
+
+ u8 *data_bytes = (u8 *) data;
+
+ if (!dev->checkpt_buffer)
+ return 0;
+
+ if (dev->checkpt_open_write)
+ return -1;
+
+ while (i < n_bytes && ok) {
+
+ if (dev->checkpt_byte_offs < 0 ||
+ dev->checkpt_byte_offs >= dev->data_bytes_per_chunk) {
+
+ if (dev->checkpt_cur_block < 0) {
+ yaffs2_checkpt_find_block(dev);
+ dev->checkpt_cur_chunk = 0;
+ }
+
+ if (dev->checkpt_cur_block < 0)
+ ok = 0;
+ else {
+ chunk = dev->checkpt_cur_block *
+ dev->param.chunks_per_block +
+ dev->checkpt_cur_chunk;
+
+ realigned_chunk = chunk - dev->chunk_offset;
+
+ dev->n_page_reads++;
+
+ /* read in the next chunk */
+ dev->param.read_chunk_tags_fn(dev,
+ realigned_chunk,
+ dev->
+ checkpt_buffer,
+ &tags);
+
+ if (tags.chunk_id != (dev->checkpt_page_seq + 1)
+ || tags.ecc_result > YAFFS_ECC_RESULT_FIXED
+ || tags.seq_number !=
+ YAFFS_SEQUENCE_CHECKPOINT_DATA)
+ ok = 0;
+
+ dev->checkpt_byte_offs = 0;
+ dev->checkpt_page_seq++;
+ dev->checkpt_cur_chunk++;
+
+ if (dev->checkpt_cur_chunk >=
+ dev->param.chunks_per_block)
+ dev->checkpt_cur_block = -1;
+ }
+ }
+
+ if (ok) {
+ *data_bytes =
+ dev->checkpt_buffer[dev->checkpt_byte_offs];
+ dev->checkpt_sum += *data_bytes;
+ dev->checkpt_xor ^= *data_bytes;
+ dev->checkpt_byte_offs++;
+ i++;
+ data_bytes++;
+ dev->checkpt_byte_count++;
+ }
+ }
+
+ return i;
+}
+
+int yaffs_checkpt_close(struct yaffs_dev *dev)
+{
+
+ if (dev->checkpt_open_write) {
+ if (dev->checkpt_byte_offs != 0)
+ yaffs2_checkpt_flush_buffer(dev);
+ } else if (dev->checkpt_block_list) {
+ int i;
+ for (i = 0;
+ i < dev->blocks_in_checkpt
+ && dev->checkpt_block_list[i] >= 0; i++) {
+ int blk = dev->checkpt_block_list[i];
+ struct yaffs_block_info *bi = NULL;
+ if (dev->internal_start_block <= blk
+ && blk <= dev->internal_end_block)
+ bi = yaffs_get_block_info(dev, blk);
+ if (bi && bi->block_state == YAFFS_BLOCK_STATE_EMPTY)
+ bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
+ else {
+ /* Todo this looks odd... */
+ }
+ }
+ YFREE(dev->checkpt_block_list);
+ dev->checkpt_block_list = NULL;
+ }
+
+ dev->n_free_chunks -=
+ dev->blocks_in_checkpt * dev->param.chunks_per_block;
+ dev->n_erased_blocks -= dev->blocks_in_checkpt;
+
+ T(YAFFS_TRACE_CHECKPOINT, (TSTR("checkpoint byte count %d" TENDSTR),
+ dev->checkpt_byte_count));
+
+ if (dev->checkpt_buffer) {
+ /* free the buffer */
+ YFREE(dev->checkpt_buffer);
+ dev->checkpt_buffer = NULL;
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+int yaffs2_checkpt_invalidate_stream(struct yaffs_dev *dev)
+{
+ /* Erase the checkpoint data */
+
+ T(YAFFS_TRACE_CHECKPOINT,
+ (TSTR("checkpoint invalidate of %d blocks" TENDSTR),
+ dev->blocks_in_checkpt));
+
+ return yaffs_checkpt_erase(dev);
+}
diff --git a/fs/yaffs2/yaffs_checkptrw.h b/fs/yaffs2/yaffs_checkptrw.h
new file mode 100644
index 0000000..361c606
--- /dev/null
+++ b/fs/yaffs2/yaffs_checkptrw.h
@@ -0,0 +1,33 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ * for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@xxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_CHECKPTRW_H__
+#define __YAFFS_CHECKPTRW_H__
+
+#include "yaffs_guts.h"
+
+int yaffs2_checkpt_open(struct yaffs_dev *dev, int writing);
+
+int yaffs2_checkpt_wr(struct yaffs_dev *dev, const void *data, int n_bytes);
+
+int yaffs2_checkpt_rd(struct yaffs_dev *dev, void *data, int n_bytes);
+
+int yaffs2_get_checkpt_sum(struct yaffs_dev *dev, u32 * sum);
+
+int yaffs_checkpt_close(struct yaffs_dev *dev);
+
+int yaffs2_checkpt_invalidate_stream(struct yaffs_dev *dev);
+
+#endif
diff --git a/fs/yaffs2/yaffs_ecc.c b/fs/yaffs2/yaffs_ecc.c
new file mode 100644
index 0000000..e95a806
--- /dev/null
+++ b/fs/yaffs2/yaffs_ecc.c
@@ -0,0 +1,298 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ * for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@xxxxxxxxxxxx>
+ *
+ * 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.
+ */
+
+/*
+ * This code implements the ECC algorithm used in SmartMedia.
+ *
+ * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
+ * The two unused bit are set to 1.
+ * The ECC can correct single bit errors in a 256-byte page of data. Thus, two such ECC
+ * blocks are used on a 512-byte NAND page.
+ *
+ */
+
+/* Table generated by gen-ecc.c
+ * Using a table means we do not have to calculate p1..p4 and p1'..p4'
+ * for each byte of data. These are instead provided in a table in bits7..2.
+ * Bit 0 of each entry indicates whether the entry has an odd or even parity, and therefore
+ * this bytes influence on the line parity.
+ */
+
+#include "yportenv.h"
+
+#include "yaffs_ecc.h"
+
+static const unsigned char column_parity_table[] = {
+ 0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
+ 0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
+ 0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
+ 0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
+ 0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
+ 0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
+ 0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
+ 0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
+ 0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
+ 0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
+ 0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
+ 0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
+ 0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
+ 0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
+ 0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
+ 0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
+ 0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
+ 0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
+ 0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
+ 0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
+ 0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
+ 0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
+ 0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
+ 0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
+ 0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
+ 0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
+ 0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
+ 0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
+ 0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
+ 0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
+ 0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
+ 0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
+};
+
+
+/* Calculate the ECC for a 256-byte block of data */
+void yaffs_ecc_cacl(const unsigned char *data, unsigned char *ecc)
+{
+ unsigned int i;
+
+ unsigned char col_parity = 0;
+ unsigned char line_parity = 0;
+ unsigned char line_parity_prime = 0;
+ unsigned char t;
+ unsigned char b;
+
+ for (i = 0; i < 256; i++) {
+ b = column_parity_table[*data++];
+ col_parity ^= b;
+
+ if (b & 0x01) { /* odd number of bits in the byte */
+ line_parity ^= i;
+ line_parity_prime ^= ~i;
+ }
+ }
+
+ ecc[2] = (~col_parity) | 0x03;
+
+ t = 0;
+ if (line_parity & 0x80)
+ t |= 0x80;
+ if (line_parity_prime & 0x80)
+ t |= 0x40;
+ if (line_parity & 0x40)
+ t |= 0x20;
+ if (line_parity_prime & 0x40)
+ t |= 0x10;
+ if (line_parity & 0x20)
+ t |= 0x08;
+ if (line_parity_prime & 0x20)
+ t |= 0x04;
+ if (line_parity & 0x10)
+ t |= 0x02;
+ if (line_parity_prime & 0x10)
+ t |= 0x01;
+ ecc[1] = ~t;
+
+ t = 0;
+ if (line_parity & 0x08)
+ t |= 0x80;
+ if (line_parity_prime & 0x08)
+ t |= 0x40;
+ if (line_parity & 0x04)
+ t |= 0x20;
+ if (line_parity_prime & 0x04)
+ t |= 0x10;
+ if (line_parity & 0x02)
+ t |= 0x08;
+ if (line_parity_prime & 0x02)
+ t |= 0x04;
+ if (line_parity & 0x01)
+ t |= 0x02;
+ if (line_parity_prime & 0x01)
+ t |= 0x01;
+ ecc[0] = ~t;
+
+#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
+ /* Swap the bytes into the wrong order */
+ t = ecc[0];
+ ecc[0] = ecc[1];
+ ecc[1] = t;
+#endif
+}
+
+/* Correct the ECC on a 256 byte block of data */
+
+int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
+ const unsigned char *test_ecc)
+{
+ unsigned char d0, d1, d2; /* deltas */
+
+ d0 = read_ecc[0] ^ test_ecc[0];
+ d1 = read_ecc[1] ^ test_ecc[1];
+ d2 = read_ecc[2] ^ test_ecc[2];
+
+ if ((d0 | d1 | d2) == 0)
+ return 0; /* no error */
+
+ if (((d0 ^ (d0 >> 1)) & 0x55) == 0x55 &&
+ ((d1 ^ (d1 >> 1)) & 0x55) == 0x55 &&
+ ((d2 ^ (d2 >> 1)) & 0x54) == 0x54) {
+ /* Single bit (recoverable) error in data */
+
+ unsigned byte;
+ unsigned bit;
+
+#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
+ /* swap the bytes to correct for the wrong order */
+ unsigned char t;
+
+ t = d0;
+ d0 = d1;
+ d1 = t;
+#endif
+
+ bit = byte = 0;
+
+ if (d1 & 0x80)
+ byte |= 0x80;
+ if (d1 & 0x20)
+ byte |= 0x40;
+ if (d1 & 0x08)
+ byte |= 0x20;
+ if (d1 & 0x02)
+ byte |= 0x10;
+ if (d0 & 0x80)
+ byte |= 0x08;
+ if (d0 & 0x20)
+ byte |= 0x04;
+ if (d0 & 0x08)
+ byte |= 0x02;
+ if (d0 & 0x02)
+ byte |= 0x01;
+
+ if (d2 & 0x80)
+ bit |= 0x04;
+ if (d2 & 0x20)
+ bit |= 0x02;
+ if (d2 & 0x08)
+ bit |= 0x01;
+
+ data[byte] ^= (1 << bit);
+
+ return 1; /* Corrected the error */
+ }
+
+ if ((hweight8(d0) + hweight8(d1) + hweight8(d2)) == 1) {
+ /* Reccoverable error in ecc */
+
+ read_ecc[0] = test_ecc[0];
+ read_ecc[1] = test_ecc[1];
+ read_ecc[2] = test_ecc[2];
+
+ return 1; /* Corrected the error */
+ }
+
+ /* Unrecoverable error */
+
+ return -1;
+
+}
+
+/*
+ * ECCxxxOther does ECC calcs on arbitrary n bytes of data
+ */
+void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes,
+ struct yaffs_ecc_other *ecc_other)
+{
+ unsigned int i;
+
+ unsigned char col_parity = 0;
+ unsigned line_parity = 0;
+ unsigned line_parity_prime = 0;
+ unsigned char b;
+
+ for (i = 0; i < n_bytes; i++) {
+ b = column_parity_table[*data++];
+ col_parity ^= b;
+
+ if (b & 0x01) {
+ /* odd number of bits in the byte */
+ line_parity ^= i;
+ line_parity_prime ^= ~i;
+ }
+
+ }
+
+ ecc_other->col_parity = (col_parity >> 2) & 0x3f;
+ ecc_other->line_parity = line_parity;
+ ecc_other->line_parity_prime = line_parity_prime;
+}
+
+int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes,
+ struct yaffs_ecc_other *read_ecc,
+ const struct yaffs_ecc_other *test_ecc)
+{
+ unsigned char delta_col; /* column parity delta */
+ unsigned delta_line; /* line parity delta */
+ unsigned delta_line_prime; /* line parity delta */
+ unsigned bit;
+
+ delta_col = read_ecc->col_parity ^ test_ecc->col_parity;
+ delta_line = read_ecc->line_parity ^ test_ecc->line_parity;
+ delta_line_prime =
+ read_ecc->line_parity_prime ^ test_ecc->line_parity_prime;
+
+ if ((delta_col | delta_line | delta_line_prime) == 0)
+ return 0; /* no error */
+
+ if (delta_line == ~delta_line_prime &&
+ (((delta_col ^ (delta_col >> 1)) & 0x15) == 0x15)) {
+ /* Single bit (recoverable) error in data */
+
+ bit = 0;
+
+ if (delta_col & 0x20)
+ bit |= 0x04;
+ if (delta_col & 0x08)
+ bit |= 0x02;
+ if (delta_col & 0x02)
+ bit |= 0x01;
+
+ if (delta_line >= n_bytes)
+ return -1;
+
+ data[delta_line] ^= (1 << bit);
+
+ return 1; /* corrected */
+ }
+
+ if ((hweight32(delta_line) +
+ hweight32(delta_line_prime) +
+ hweight8(delta_col)) == 1) {
+ /* Reccoverable error in ecc */
+
+ *read_ecc = *test_ecc;
+ return 1; /* corrected */
+ }
+
+ /* Unrecoverable error */
+
+ return -1;
+}
diff --git a/fs/yaffs2/yaffs_ecc.h b/fs/yaffs2/yaffs_ecc.h
new file mode 100644
index 0000000..b0c461d
--- /dev/null
+++ b/fs/yaffs2/yaffs_ecc.h
@@ -0,0 +1,44 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ * for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@xxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+/*
+ * This code implements the ECC algorithm used in SmartMedia.
+ *
+ * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
+ * The two unused bit are set to 1.
+ * The ECC can correct single bit errors in a 256-byte page of data. Thus, two such ECC
+ * blocks are used on a 512-byte NAND page.
+ *
+ */
+
+#ifndef __YAFFS_ECC_H__
+#define __YAFFS_ECC_H__
+
+struct yaffs_ecc_other {
+ unsigned char col_parity;
+ unsigned line_parity;
+ unsigned line_parity_prime;
+};
+
+void yaffs_ecc_cacl(const unsigned char *data, unsigned char *ecc);
+int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
+ const unsigned char *test_ecc);
+
+void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes,
+ struct yaffs_ecc_other *ecc);
+int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes,
+ struct yaffs_ecc_other *read_ecc,
+ const struct yaffs_ecc_other *test_ecc);
+#endif
--
1.7.1
--
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