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Commit 7150962d637cf38617924f7f72ea00612283eb89

Authored by Arend van Spriel
Committed by John W. Linville
1 parent dabd3001f9
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

lib: crc8: add new library module providing crc8 algorithm 

The brcm80211 driver in staging tree uses a crc8 function. Based on
feedback from John Linville to move this to lib directory, the linux
source has been searched. Although there is currently only one other
kernel driver using this algorithm (ie. drivers/ssb) we are providing
this as a library function for others to use.

Cc: linux-kernel@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: Dan Carpenter <error27@gmail.com>
Cc: George Spelvin <linux@horizon.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: "Franky (Zhenhui) Lin" <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

Showing 4 changed files with 195 additions and 0 deletions Side-by-side Diff

include/linux/crc8.h
Diff comments   View file @ 7150962
  1 +/*
  2 + * Copyright (c) 2011 Broadcom Corporation
  3 + *
  4 + * Permission to use, copy, modify, and/or distribute this software for any
  5 + * purpose with or without fee is hereby granted, provided that the above
  6 + * copyright notice and this permission notice appear in all copies.
  7 + *
  8 + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  9 + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10 + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  11 + * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12 + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  13 + * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  14 + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15 + */
  16 +#ifndef __CRC8_H_
  17 +#define __CRC8_H_
  18 +
  19 +#include <linux/types.h>
  20 +
  21 +/* see usage of this value in crc8() description */
  22 +#define CRC8_INIT_VALUE 0xFF
  23 +
  24 +/*
  25 + * Return value of crc8() indicating valid message+crc. This is true
  26 + * if a CRC is inverted before transmission. The CRC computed over the
  27 + * whole received bitstream is _table[x], where x is the bit pattern
  28 + * of the modification (almost always 0xff).
  29 + */
  30 +#define CRC8_GOOD_VALUE(_table) (_table[0xFF])
  31 +
  32 +/* required table size for crc8 algorithm */
  33 +#define CRC8_TABLE_SIZE 256
  34 +
  35 +/* helper macro assuring right table size is used */
  36 +#define DECLARE_CRC8_TABLE(_table) \
  37 + static u8 _table[CRC8_TABLE_SIZE]
  38 +
  39 +/**
  40 + * crc8_populate_lsb - fill crc table for given polynomial in regular bit order.
  41 + *
  42 + * @table: table to be filled.
  43 + * @polynomial: polynomial for which table is to be filled.
  44 + *
  45 + * This function fills the provided table according the polynomial provided for
  46 + * regular bit order (lsb first). Polynomials in CRC algorithms are typically
  47 + * represented as shown below.
  48 + *
  49 + * poly = x^8 + x^7 + x^6 + x^4 + x^2 + 1
  50 + *
  51 + * For lsb first direction x^7 maps to the lsb. So the polynomial is as below.
  52 + *
  53 + * - lsb first: poly = 10101011(1) = 0xAB
  54 + */
  55 +void crc8_populate_lsb(u8 table[CRC8_TABLE_SIZE], u8 polynomial);
  56 +
  57 +/**
  58 + * crc8_populate_msb - fill crc table for given polynomial in reverse bit order.
  59 + *
  60 + * @table: table to be filled.
  61 + * @polynomial: polynomial for which table is to be filled.
  62 + *
  63 + * This function fills the provided table according the polynomial provided for
  64 + * reverse bit order (msb first). Polynomials in CRC algorithms are typically
  65 + * represented as shown below.
  66 + *
  67 + * poly = x^8 + x^7 + x^6 + x^4 + x^2 + 1
  68 + *
  69 + * For msb first direction x^7 maps to the msb. So the polynomial is as below.
  70 + *
  71 + * - msb first: poly = (1)11010101 = 0xD5
  72 + */
  73 +void crc8_populate_msb(u8 table[CRC8_TABLE_SIZE], u8 polynomial);
  74 +
  75 +/**
  76 + * crc8() - calculate a crc8 over the given input data.
  77 + *
  78 + * @table: crc table used for calculation.
  79 + * @pdata: pointer to data buffer.
  80 + * @nbytes: number of bytes in data buffer.
  81 + * @crc: previous returned crc8 value.
  82 + *
  83 + * The CRC8 is calculated using the polynomial given in crc8_populate_msb()
  84 + * or crc8_populate_lsb().
  85 + *
  86 + * The caller provides the initial value (either %CRC8_INIT_VALUE
  87 + * or the previous returned value) to allow for processing of
  88 + * discontiguous blocks of data. When generating the CRC the
  89 + * caller is responsible for complementing the final return value
  90 + * and inserting it into the byte stream. When validating a byte
  91 + * stream (including CRC8), a final return value of %CRC8_GOOD_VALUE
  92 + * indicates the byte stream data can be considered valid.
  93 + *
  94 + * Reference:
  95 + * "A Painless Guide to CRC Error Detection Algorithms", ver 3, Aug 1993
  96 + * Williams, Ross N., ross<at>ross.net
  97 + * (see URL http://www.ross.net/crc/download/crc_v3.txt).
  98 + */
  99 +u8 crc8(const u8 table[CRC8_TABLE_SIZE], u8 *pdata, size_t nbytes, u8 crc);
  100 +
  101 +#endif /* __CRC8_H_ */
... ... @@ -89,6 +89,13 @@
89 89 require M here. See Castagnoli93.
90 90 Module will be libcrc32c.
91 91  
  92 +config CRC8
  93 + tristate "CRC8 function"
  94 + help
  95 + This option provides CRC8 function. Drivers may select this
  96 + when they need to do cyclic redundancy check according CRC8
  97 + algorithm. Module will be called crc8.
  98 +
92 99 config AUDIT_GENERIC
93 100 bool
94 101 depends on AUDIT && !AUDIT_ARCH
... ... @@ -65,6 +65,7 @@
65 65 obj-$(CONFIG_CRC32) += crc32.o
66 66 obj-$(CONFIG_CRC7) += crc7.o
67 67 obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
  68 +obj-$(CONFIG_CRC8) += crc8.o
68 69 obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
69 70  
70 71 obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/
  1 +/*
  2 + * Copyright (c) 2011 Broadcom Corporation
  3 + *
  4 + * Permission to use, copy, modify, and/or distribute this software for any
  5 + * purpose with or without fee is hereby granted, provided that the above
  6 + * copyright notice and this permission notice appear in all copies.
  7 + *
  8 + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  9 + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10 + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  11 + * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12 + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  13 + * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  14 + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15 + */
  16 +
  17 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18 +
  19 +#include <linux/module.h>
  20 +#include <linux/crc8.h>
  21 +#include <linux/printk.h>
  22 +
  23 +/*
  24 + * crc8_populate_msb - fill crc table for given polynomial in reverse bit order.
  25 + *
  26 + * table: table to be filled.
  27 + * polynomial: polynomial for which table is to be filled.
  28 + */
  29 +void crc8_populate_msb(u8 table[CRC8_TABLE_SIZE], u8 polynomial)
  30 +{
  31 + int i, j;
  32 + const u8 msbit = 0x80;
  33 + u8 t = msbit;
  34 +
  35 + table[0] = 0;
  36 +
  37 + for (i = 1; i < CRC8_TABLE_SIZE; i *= 2) {
  38 + t = (t << 1) ^ (t & msbit ? polynomial : 0);
  39 + for (j = 0; j < i; j++)
  40 + table[i+j] = table[j] ^ t;
  41 + }
  42 +}
  43 +EXPORT_SYMBOL(crc8_populate_msb);
  44 +
  45 +/*
  46 + * crc8_populate_lsb - fill crc table for given polynomial in regular bit order.
  47 + *
  48 + * table: table to be filled.
  49 + * polynomial: polynomial for which table is to be filled.
  50 + */
  51 +void crc8_populate_lsb(u8 table[CRC8_TABLE_SIZE], u8 polynomial)
  52 +{
  53 + int i, j;
  54 + u8 t = 1;
  55 +
  56 + table[0] = 0;
  57 +
  58 + for (i = (CRC8_TABLE_SIZE >> 1); i; i >>= 1) {
  59 + t = (t >> 1) ^ (t & 1 ? polynomial : 0);
  60 + for (j = 0; j < CRC8_TABLE_SIZE; j += 2*i)
  61 + table[i+j] = table[j] ^ t;
  62 + }
  63 +}
  64 +EXPORT_SYMBOL(crc8_populate_lsb);
  65 +
  66 +/*
  67 + * crc8 - calculate a crc8 over the given input data.
  68 + *
  69 + * table: crc table used for calculation.
  70 + * pdata: pointer to data buffer.
  71 + * nbytes: number of bytes in data buffer.
  72 + * crc: previous returned crc8 value.
  73 + */
  74 +u8 crc8(const u8 table[CRC8_TABLE_SIZE], u8 *pdata, size_t nbytes, u8 crc)
  75 +{
  76 + /* loop over the buffer data */
  77 + while (nbytes-- > 0)
  78 + crc = table[(crc ^ *pdata++) & 0xff];
  79 +
  80 + return crc;
  81 +}
  82 +EXPORT_SYMBOL(crc8);
  83 +
  84 +MODULE_DESCRIPTION("CRC8 (by Williams, Ross N.) function");
  85 +MODULE_AUTHOR("Broadcom Corporation");
  86 +MODULE_LICENSE("Dual BSD/GPL");