[PATCH v2 06/18] drivers/fsi: Add FSI crc calculators to library
From: christopher.lee.bostic at gmail.com <hidden>
Date: 2017-01-12 22:27:15
Also in:
linux-devicetree, lkml
Subsystem:
crc library, library code, the rest · Maintainers:
Eric Biggers, Andrew Morton, Linus Torvalds
From: Jeremy Kerr <jk@ozlabs.org> 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. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Chris Bostic <redacted> --- V2 - Move crc utilities out of the FSI core and move into linux/lib. --- include/linux/crc-fsi.h | 29 +++++++++++++++++++++++++++++ lib/Makefile | 1 + lib/crc-fsi.c | 39 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 69 insertions(+) create mode 100644 include/linux/crc-fsi.h create mode 100644 lib/crc-fsi.c
diff --git a/include/linux/crc-fsi.h b/include/linux/crc-fsi.h
new file mode 100644
index 0000000..e96d2f0
--- /dev/null
+++ b/include/linux/crc-fsi.h@@ -0,0 +1,29 @@ +/* + * FSI CRC calculator + * + * Copyright (C) IBM Corporation 2016 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * + * Implements the standard FSI CRC: + * + * Width 1 - 32 + * Poly 0x0017 (x^4 + x^2 + x^1 + x^0) + */ + +#ifndef CRC_FSI_H +#define CRC_FSI_H + +#include <linux/types.h> + +uint8_t crc_fsi(uint8_t c, uint64_t x, int bits); + +#endif /* CRC_FSI_H */
diff --git a/lib/Makefile b/lib/Makefile
index 50144a3..c840628 100644
--- a/lib/Makefile
+++ b/lib/Makefile@@ -230,3 +230,4 @@ obj-$(CONFIG_UBSAN) += ubsan.o UBSAN_SANITIZE_ubsan.o := n obj-$(CONFIG_SBITMAP) += sbitmap.o +obj-$(CONFIG_FSI) += crc-fsi.o
diff --git a/lib/crc-fsi.c b/lib/crc-fsi.c
new file mode 100644
index 0000000..55cfe9d
--- /dev/null
+++ b/lib/crc-fsi.c@@ -0,0 +1,39 @@ +/* + * FSI CRC calculator + * + * Copyright (C) IBM Corporation 2016 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/module.h> +#include <linux/types.h> +#include <linux/crc-fsi.h> + +/* crc helpers */ +static const uint8_t crc_fsi_tab[] = { + 0x0, 0x7, 0xe, 0x9, 0xb, 0xc, 0x5, 0x2, + 0x1, 0x6, 0xf, 0x8, 0xa, 0xd, 0x4, 0x3, +}; + +uint8_t crc_fsi(uint8_t c, uint64_t x, int bits) +{ + int i; + + /* Align to 4-bits */ + bits = (bits + 3) & ~0x3; + + /* Calculate crc4 over four-bit nibbles, starting at the MSbit */ + for (i = bits; i >= 0; i -= 4) + c = crc_fsi_tab[c ^ ((x >> i) & 0xf)]; + + return c; +} +EXPORT_SYMBOL_GPL(crc_fsi);
--
1.8.2.2