CRC-8这个协议是以公司存在的，不知道要是禁用会产生什么后果

/** Copyright (c) 2011 Broadcom Corporation** Permission to use, copy, modify, and/or distribute this software for any* purpose with or without fee is hereby granted, provided that the above* copyright notice and this permission notice appear in all copies.** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.*/
#ifndef __CRC8_H_
#define __CRC8_H_#include <linux/types.h>/* see usage of this value in crc8() description */
#define CRC8_INIT_VALUE		0xFF/** Return value of crc8() indicating valid message+crc. This is true* if a CRC is inverted before transmission. The CRC computed over the* whole received bitstream is _table[x], where x is the bit pattern* of the modification (almost always 0xff).*/
#define CRC8_GOOD_VALUE(_table)	(_table[0xFF])/* required table size for crc8 algorithm */
#define CRC8_TABLE_SIZE			256/* helper macro assuring right table size is used */
#define DECLARE_CRC8_TABLE(_table) \static u8 _table[CRC8_TABLE_SIZE]/*** crc8_populate_lsb - fill crc table for given polynomial in regular bit order.** @table:	table to be filled.* @polynomial:	polynomial for which table is to be filled.** This function fills the provided table according the polynomial provided for* regular bit order (lsb first). Polynomials in CRC algorithms are typically* represented as shown below.**	poly = x^8 + x^7 + x^6 + x^4 + x^2 + 1** For lsb first direction x^7 maps to the lsb. So the polynomial is as below.** - lsb first: poly = 10101011(1) = 0xAB*/
void crc8_populate_lsb(u8 table[CRC8_TABLE_SIZE], u8 polynomial);/*** crc8_populate_msb - fill crc table for given polynomial in reverse bit order.** @table:	table to be filled.* @polynomial:	polynomial for which table is to be filled.** This function fills the provided table according the polynomial provided for* reverse bit order (msb first). Polynomials in CRC algorithms are typically* represented as shown below.**	poly = x^8 + x^7 + x^6 + x^4 + x^2 + 1** For msb first direction x^7 maps to the msb. So the polynomial is as below.** - msb first: poly = (1)11010101 = 0xD5*/
void crc8_populate_msb(u8 table[CRC8_TABLE_SIZE], u8 polynomial);/*** crc8() - calculate a crc8 over the given input data.** @table:	crc table used for calculation.* @pdata:	pointer to data buffer.* @nbytes:	number of bytes in data buffer.* @crc:	previous returned crc8 value.** The CRC8 is calculated using the polynomial given in crc8_populate_msb()* or crc8_populate_lsb().** The caller provides the initial value (either %CRC8_INIT_VALUE* or the previous returned value) to allow for processing of* discontiguous blocks of data.  When generating the CRC the* caller is responsible for complementing the final return value* and inserting it into the byte stream.  When validating a byte* stream (including CRC8), a final return value of %CRC8_GOOD_VALUE* indicates the byte stream data can be considered valid.** Reference:* "A Painless Guide to CRC Error Detection Algorithms", ver 3, Aug 1993* Williams, Ross N., ross<at>ross.net* (see URL http://www.ross.net/crc/download/crc_v3.txt).*/
u8 crc8(const u8 table[CRC8_TABLE_SIZE], u8 *pdata, size_t nbytes, u8 crc);#endif /* __CRC8_H_ */

/** Copyright (c) 2011 Broadcom Corporation** Permission to use, copy, modify, and/or distribute this software for any* purpose with or without fee is hereby granted, provided that the above* copyright notice and this permission notice appear in all copies.** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.*/#define pr_fmt(fmt)        KBUILD_MODNAME ": " fmt#include <linux/module.h>
#include <linux/crc8.h>
#include <linux/printk.h>/*** crc8_populate_msb - fill crc table for given polynomial in reverse bit order.** @table:    table to be filled.* @polynomial:    polynomial for which table is to be filled.*/
void crc8_populate_msb(u8 table[CRC8_TABLE_SIZE], u8 polynomial)
{int i, j;const u8 msbit = 0x80;u8 t = msbit;table[0] = 0;for (i = 1; i < CRC8_TABLE_SIZE; i *= 2) {t = (t << 1) ^ (t & msbit ? polynomial : 0);for (j = 0; j < i; j++)table[i+j] = table[j] ^ t;}
}
EXPORT_SYMBOL(crc8_populate_msb);/*** crc8_populate_lsb - fill crc table for given polynomial in regular bit order.** @table:    table to be filled.* @polynomial:    polynomial for which table is to be filled.*/
void crc8_populate_lsb(u8 table[CRC8_TABLE_SIZE], u8 polynomial)
{int i, j;u8 t = 1;table[0] = 0;for (i = (CRC8_TABLE_SIZE >> 1); i; i >>= 1) {t = (t >> 1) ^ (t & 1 ? polynomial : 0);for (j = 0; j < CRC8_TABLE_SIZE; j += 2*i)table[i+j] = table[j] ^ t;}
}
EXPORT_SYMBOL(crc8_populate_lsb);/*** crc8 - calculate a crc8 over the given input data.** @table: crc table used for calculation.* @pdata: pointer to data buffer.* @nbytes: number of bytes in data buffer.* @crc: previous returned crc8 value.*/
u8 crc8(const u8 table[CRC8_TABLE_SIZE], u8 *pdata, size_t nbytes, u8 crc)
{/* loop over the buffer data */while (nbytes-- > 0)crc = table[(crc ^ *pdata++) & 0xff];return crc;
}
EXPORT_SYMBOL(crc8);MODULE_DESCRIPTION("CRC8 (by Williams, Ross N.) function");
MODULE_AUTHOR("Broadcom Corporation");
MODULE_LICENSE("Dual BSD/GPL");