lib: Port CRC8 implementation from Linux kernel

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 90 insertions, 0 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index 860d471de9..67680adbb5 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -118,6 +118,13 @@ config CRC_CCITT
 	  the kernel tree does. Such modules that use library CRC-CCITT
 	  functions require M here.
 
+config CRC8
+        bool "CRC8 function"
+	help
+	  This option provides CRC8 function. Drivers may select this
+	  when they need to do cyclic redundancy check according CRC8
+	  algorithm. Module will be called crc8.
+
 source lib/gui/Kconfig
 
 source lib/fonts/Kconfig
diff --git a/lib/Makefile b/lib/Makefile
index 693945fb2c..bd2dae7643 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -65,6 +65,7 @@ obj-y			+= int_sqrt.o
 obj-y			+= parseopt.o
 obj-y			+= clz_ctz.o
 obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o
+obj-$(CONFIG_CRC8)	+= crc8.o
 
 # GCC library routines
 obj-$(CONFIG_GENERIC_LIB_ASHLDI3) += ashldi3.o
diff --git a/lib/crc8.c b/lib/crc8.c
new file mode 100644
index 0000000000..a89160bded
--- /dev/null
+++ b/lib/crc8.c
@@ -0,0 +1,82 @@
+/*
+ * 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.
+ */
+#include <module.h>
+#include <linux/crc8.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");