summaryrefslogtreecommitdiff
path: root/lib
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-04 06:55:59 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-04 06:55:59 +0300
commitf4dd029ee0b92b77769a1ac6dce03e829e74763e (patch)
treef918cc855a8171d68746ab61a32b9e61b024845b /lib
parent974668417b74ec5f68df2411f53b3d3812565059 (diff)
parentcbbdc6082917a92da0fc07cee255111de16ed64a (diff)
downloadlinux-f4dd029ee0b92b77769a1ac6dce03e829e74763e.tar.xz
Merge tag 'char-misc-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc updates from Greg KH: "Here is the "big" char/misc driver patchset for 4.13-rc1. Lots of stuff in here, a large thunderbolt update, w1 driver header reorg, the new mux driver subsystem, google firmware driver updates, and a raft of other smaller things. Full details in the shortlog. All of these have been in linux-next for a while with the only reported issue being a merge problem with this tree and the jc-docs tree in the w1 documentation area" * tag 'char-misc-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (147 commits) misc: apds990x: Use sysfs_match_string() helper mei: drop unreachable code in mei_start mei: validate the message header only in first fragment. DocBook: w1: Update W1 file locations and names in DocBook mux: adg792a: always require I2C support nvmem: rockchip-efuse: add support for rk322x-efuse nvmem: core: add locking to nvmem_find_cell nvmem: core: Call put_device() in nvmem_unregister() nvmem: core: fix leaks on registration errors nvmem: correct Broadcom OTP controller driver writes w1: Add subsystem kernel public interface drivers/fsi: Add module license to core driver drivers/fsi: Use asynchronous slave mode drivers/fsi: Add hub master support drivers/fsi: Add SCOM FSI client device driver drivers/fsi/gpio: Add tracepoints for GPIO master drivers/fsi: Add GPIO based FSI master drivers/fsi: Document FSI master sysfs files in ABI drivers/fsi: Add error handling for slave drivers/fsi: Add tracepoints for low-level operations ...
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig8
-rw-r--r--lib/Makefile1
-rw-r--r--lib/crc4.c46
3 files changed, 55 insertions, 0 deletions
diff --git a/lib/Kconfig b/lib/Kconfig
index 0c8b78a9ae2e..d2fd2623721e 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 07fbe6a75692..7fb6ab799b8e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -96,6 +96,7 @@ 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 000000000000..cf6db46661be
--- /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 <linux/crc4.h>
+#include <linux/module.h>
+
+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");