From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755484AbdEKVHL (ORCPT ); Thu, 11 May 2017 17:07:11 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48524 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933310AbdEKVBV (ORCPT ); Thu, 11 May 2017 17:01:21 -0400 From: Christopher Bostic To: robh+dt@kernel.org, mark.rutland@arm.com, linux@armlinux.org.uk, rostedt@goodmis.org, mingo@redhat.com, gregkh@linuxfoundation.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Jeremy Kerr , joel@jms.id.au, linux-kernel@vger.kernel.org, andrew@aj.id.au, alistair@popple.id.au, benh@kernel.crashing.org, Chris Bostic Subject: [PATCH v7 04/23] lib: Add crc4 module Date: Thu, 11 May 2017 16:00:41 -0500 X-Mailer: git-send-email 2.10.1 (Apple Git-78) In-Reply-To: <20170511210101.78409-1-cbostic@linux.vnet.ibm.com> References: <20170511210101.78409-1-cbostic@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17051121-0008-0000-0000-0000021A03DD X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007048; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000211; SDB=6.00859255; UDB=6.00425867; IPR=6.00638772; BA=6.00005345; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015417; XFM=3.00000015; UTC=2017-05-11 21:01:18 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17051121-0009-0000-0000-0000353D4089 Message-Id: <20170511210101.78409-5-cbostic@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-11_17:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705110114 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jeremy Kerr Add a little helper for crc4 calculations. This works 4-bits-at-a-time, using a simple table approach. We will need this in the FSI core code, as well as any master implementations that need to calculate CRCs in software. Signed-off-by: Jeremy Kerr Signed-off-by: Chris Bostic Signed-off-by: Joel Stanley --- include/linux/crc4.h | 8 ++++++++ lib/Kconfig | 8 ++++++++ lib/Makefile | 1 + lib/crc4.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 63 insertions(+) create mode 100644 include/linux/crc4.h create mode 100644 lib/crc4.c diff --git a/include/linux/crc4.h b/include/linux/crc4.h new file mode 100644 index 0000000..8f739f1 --- /dev/null +++ b/include/linux/crc4.h @@ -0,0 +1,8 @@ +#ifndef _LINUX_CRC4_H +#define _LINUX_CRC4_H + +#include + +extern uint8_t crc4(uint8_t c, uint64_t x, int bits); + +#endif /* _LINUX_CRC4_H */ diff --git a/lib/Kconfig b/lib/Kconfig index 0c8b78a..d2fd262 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -158,6 +158,14 @@ config CRC32_BIT endchoice +config CRC4 + tristate "CRC4 functions" + help + This option is provided for the case where no in-kernel-tree + modules require CRC4 functions, but a module built outside + the kernel tree does. Such modules that use library CRC4 + functions require M here. + config CRC7 tristate "CRC7 functions" help diff --git a/lib/Makefile b/lib/Makefile index 320ac46a..63b3c28 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -98,6 +98,7 @@ obj-$(CONFIG_CRC_T10DIF)+= crc-t10dif.o obj-$(CONFIG_CRC_ITU_T) += crc-itu-t.o obj-$(CONFIG_CRC32) += crc32.o obj-$(CONFIG_CRC32_SELFTEST) += crc32test.o +obj-$(CONFIG_CRC4) += crc4.o obj-$(CONFIG_CRC7) += crc7.o obj-$(CONFIG_LIBCRC32C) += libcrc32c.o obj-$(CONFIG_CRC8) += crc8.o diff --git a/lib/crc4.c b/lib/crc4.c new file mode 100644 index 0000000..cf6db46 --- /dev/null +++ b/lib/crc4.c @@ -0,0 +1,46 @@ +/* + * crc4.c - simple crc-4 calculations. + * + * This source code is licensed under the GNU General Public License, Version + * 2. See the file COPYING for more details. + */ + +#include +#include + +static const uint8_t crc4_tab[] = { + 0x0, 0x7, 0xe, 0x9, 0xb, 0xc, 0x5, 0x2, + 0x1, 0x6, 0xf, 0x8, 0xa, 0xd, 0x4, 0x3, +}; + +/** + * crc4 - calculate the 4-bit crc of a value. + * @crc: starting crc4 + * @x: value to checksum + * @bits: number of bits in @x to checksum + * + * Returns the crc4 value of @x, using polynomial 0b10111. + * + * The @x value is treated as left-aligned, and bits above @bits are ignored + * in the crc calculations. + */ +uint8_t crc4(uint8_t c, uint64_t x, int bits) +{ + int i; + + /* mask off anything above the top bit */ + x &= (1ull << bits) - 1; + + /* Align to 4-bits */ + bits = (bits + 3) & ~0x3; + + /* Calculate crc4 over four-bit nibbles, starting at the MSbit */ + for (i = bits - 4; i >= 0; i -= 4) + c = crc4_tab[c ^ ((x >> i) & 0xf)]; + + return c; +} +EXPORT_SYMBOL_GPL(crc4); + +MODULE_DESCRIPTION("CRC4 calculations"); +MODULE_LICENSE("GPL"); -- 1.8.2.2