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Violators will be prosecuted; Wed, 29 Mar 2017 11:43:51 -0600 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v2THhpkp8585494; Wed, 29 Mar 2017 10:43:51 -0700 Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E3B0578038; Wed, 29 Mar 2017 11:43:50 -0600 (MDT) Received: from christophersmbp.austin.ibm.com (unknown [9.41.174.103]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP id 27B6678037; Wed, 29 Mar 2017 11:43:50 -0600 (MDT) 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 Subject: [PATCH v4 04/23] drivers/fsi: Add crc4 helpers Date: Wed, 29 Mar 2017 12:43:21 -0500 X-Mailer: git-send-email 2.10.1 (Apple Git-78) In-Reply-To: <20170329174340.89109-1-cbostic@linux.vnet.ibm.com> References: <20170329174340.89109-1-cbostic@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17032917-0016-0000-0000-00000676ABF3 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006872; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000206; SDB=6.00840412; UDB=6.00413637; IPR=6.00618406; BA=6.00005248; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014855; XFM=3.00000013; UTC=2017-03-29 17:43:55 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17032917-0017-0000-0000-0000388E7161 Message-Id: <20170329174340.89109-5-cbostic@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-03-29_13:, , 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-1703290150 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170329_104417_577763_73C0D7EC X-CRM114-Status: GOOD ( 13.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Chris Bostic , andrew@aj.id.au, alistair@popple.id.au, linux-kernel@vger.kernel.org, Jeremy Kerr , benh@kernel.crashing.org, joel@jms.id.au MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 */