From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752929AbdDJTsW (ORCPT ); Mon, 10 Apr 2017 15:48:22 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49440 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752753AbdDJTsR (ORCPT ); Mon, 10 Apr 2017 15:48:17 -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 v6 04/23] drivers/fsi: Add crc4 helpers Date: Mon, 10 Apr 2017 14:46:47 -0500 X-Mailer: git-send-email 2.10.1 (Apple Git-78) In-Reply-To: <20170410194706.64280-1-cbostic@linux.vnet.ibm.com> References: <20170410194706.64280-1-cbostic@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17041019-0024-0000-0000-0000024050C9 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006912; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00845690; UDB=6.00417057; IPR=6.00624124; BA=6.00005281; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014997; XFM=3.00000013; UTC=2017-04-10 19:47:59 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17041019-0025-0000-0000-00004341D5AF Message-Id: <20170410194706.64280-5-cbostic@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-10_15:,, 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=8.0.1-1702020001 definitions=main-1704100156 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jeremy Kerr Add some helpers for the crc checks for the slave configuration table. 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. We add this to the fsi code (rather than lib/), as we need a specific polynomial for FSI CRCs. Signed-off-by: Jeremy Kerr Signed-off-by: Chris Bostic Signed-off-by: Joel Stanley --- drivers/fsi/fsi-core.c | 24 ++++++++++++++++++++++++ drivers/fsi/fsi-master.h | 21 +++++++++++++++++++++ 2 files changed, 45 insertions(+) diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c index e90d45d..4bbca95 100644 --- a/drivers/fsi/fsi-core.c +++ b/drivers/fsi/fsi-core.c @@ -32,6 +32,30 @@ struct fsi_slave { #define to_fsi_slave(d) container_of(d, struct fsi_slave, dev) +/* crc helpers */ +static const uint8_t crc4_tab[] = { + 0x0, 0x7, 0xe, 0x9, 0xb, 0xc, 0x5, 0x2, + 0x1, 0x6, 0xf, 0x8, 0xa, 0xd, 0x4, 0x3, +}; + +uint8_t fsi_crc4(uint8_t c, uint64_t x, int bits) +{ + int i; + + /* Align to 4-bits */ + bits = (bits + 3) & ~0x3; + + /* mask off anything above the top bit */ + x &= (1ull << bits) - 1; + + /* 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(fsi_crc4); + /* FSI slave support */ static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id) { diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h index 7764b00..d6a4885 100644 --- a/drivers/fsi/fsi-master.h +++ b/drivers/fsi/fsi-master.h @@ -38,4 +38,25 @@ struct fsi_master { extern int fsi_master_register(struct fsi_master *master); extern void fsi_master_unregister(struct fsi_master *master); +/** + * crc4 helper: Given a starting crc4 state @c, calculate the crc4 vaue of @x, + * which is @bits in length. This may be required by master implementations + * that do not provide their own hardware checksums. + * + * The crc4 is performed on 4-bit chunks (which is all we need for FSI + * calculations). Typically, we'll want a starting state of 0: + * + * c = fsi_crc4(0, msg, len); + * + * To crc4 a message that includes a single start bit, initialise crc4 state + * with: + * + * c = fsi_crc4(0, 1, 1); + * + * Then update with message data: + * + * c = fsi_crc4(c, msg, len); + */ +uint8_t fsi_crc4(uint8_t c, uint64_t x, int bits); + #endif /* DRIVERS_FSI_MASTER_H */ -- 1.8.2.2