Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753992Ab0KASl5 (ORCPT ); Mon, 1 Nov 2010 14:41:57 -0400 Received: from mail-px0-f174.google.com ([209.85.212.174]:62766 "EHLO mail-px0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753802Ab0KASlw (ORCPT ); Mon, 1 Nov 2010 14:41:52 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=VF5NCJMLpBjJKAcPUqhtEtqyZAWEAg52lDJuF/WZAkKBNE/hNai04cxQcfN2gJGIKB Xo6dBvbpDRjxkebGgKrut1ZoDzs1JU72TTsUnmmKBUHlpo3JnsZfEIXffy0c0+dhq+uy p8Q1d+gu5mlLEW9Sjx6RYYdIPH0XfarOa3VmQ= From: Tracey Dent To: greg@kroah.com Cc: manningc2@actrix.gen.nz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Tracey Dent Subject: [PATCH 08/29] Staging: yaffs2: yaffs_ecc: Add files Date: Mon, 1 Nov 2010 14:40:56 -0400 Message-Id: <1288636877-7964-9-git-send-email-tdent48227@gmail.com> X-Mailer: git-send-email 1.7.3.2.146.gca209 In-Reply-To: <1288636877-7964-1-git-send-email-tdent48227@gmail.com> References: <1288636877-7964-1-git-send-email-tdent48227@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10566 Lines: 397 Adding files to yaffs2 directory. Signed-off-by: Tracey Dent --- drivers/staging/yaffs2/yaffs_ecc.c | 323 ++++++++++++++++++++++++++++++++++++ drivers/staging/yaffs2/yaffs_ecc.h | 44 +++++ 2 files changed, 367 insertions(+), 0 deletions(-) create mode 100644 drivers/staging/yaffs2/yaffs_ecc.c create mode 100644 drivers/staging/yaffs2/yaffs_ecc.h diff --git a/drivers/staging/yaffs2/yaffs_ecc.c b/drivers/staging/yaffs2/yaffs_ecc.c new file mode 100644 index 0000000..35f8747 --- /dev/null +++ b/drivers/staging/yaffs2/yaffs_ecc.c @@ -0,0 +1,323 @@ +/* + * 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 + * + * 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, +}; + +/* Count the bits in an unsigned char or a U32 */ + +static int yaffs_count_bits(unsigned char x) +{ + int r = 0; + while (x) { + if (x & 1) + r++; + x >>= 1; + } + return r; +} + +static int yaffs_count_bits32(unsigned x) +{ + int r = 0; + while (x) { + if (x & 1) + r++; + x >>= 1; + } + return r; +} + +/* 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 ((yaffs_count_bits(d0) + + yaffs_count_bits(d1) + + yaffs_count_bits(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, + 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, + yaffs_ecc_other *read_ecc, + const 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 ((yaffs_count_bits32(delta_line) + yaffs_count_bits32(delta_line_prime) + + yaffs_count_bits(delta_col)) == 1) { + /* Reccoverable error in ecc */ + + *read_ecc = *test_ecc; + return 1; /* corrected */ + } + + /* Unrecoverable error */ + + return -1; +} diff --git a/drivers/staging/yaffs2/yaffs_ecc.h b/drivers/staging/yaffs2/yaffs_ecc.h new file mode 100644 index 0000000..f505ab5 --- /dev/null +++ b/drivers/staging/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 + * + * 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__ + +typedef struct { + unsigned char col_parity; + unsigned line_parity; + unsigned line_parity_prime; +} yaffs_ecc_other; + +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, + yaffs_ecc_other *ecc); +int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes, + yaffs_ecc_other *read_ecc, + const yaffs_ecc_other *test_ecc); +#endif -- 1.7.3.2.146.gca209 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/