v4.19.13 snapshot.
diff --git a/include/linux/rslib.h b/include/linux/rslib.h
new file mode 100644
index 0000000..5974ced
--- /dev/null
+++ b/include/linux/rslib.h
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Reed Solomon encoder / decoder library
+ *
+ * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
+ *
+ * RS code lifted from reed solomon library written by Phil Karn
+ * Copyright 2002 Phil Karn, KA9Q
+ */
+#ifndef _RSLIB_H_
+#define _RSLIB_H_
+
+#include <linux/list.h>
+#include <linux/types.h> /* for gfp_t */
+#include <linux/gfp.h> /* for GFP_KERNEL */
+
+/**
+ * struct rs_codec - rs codec data
+ *
+ * @mm: Bits per symbol
+ * @nn: Symbols per block (= (1<<mm)-1)
+ * @alpha_to: log lookup table
+ * @index_of: Antilog lookup table
+ * @genpoly: Generator polynomial
+ * @nroots: Number of generator roots = number of parity symbols
+ * @fcr: First consecutive root, index form
+ * @prim: Primitive element, index form
+ * @iprim: prim-th root of 1, index form
+ * @gfpoly: The primitive generator polynominal
+ * @gffunc: Function to generate the field, if non-canonical representation
+ * @users: Users of this structure
+ * @list: List entry for the rs codec list
+*/
+struct rs_codec {
+ int mm;
+ int nn;
+ uint16_t *alpha_to;
+ uint16_t *index_of;
+ uint16_t *genpoly;
+ int nroots;
+ int fcr;
+ int prim;
+ int iprim;
+ int gfpoly;
+ int (*gffunc)(int);
+ int users;
+ struct list_head list;
+};
+
+/**
+ * struct rs_control - rs control structure per instance
+ * @codec: The codec used for this instance
+ * @buffers: Internal scratch buffers used in calls to decode_rs()
+ */
+struct rs_control {
+ struct rs_codec *codec;
+ uint16_t buffers[0];
+};
+
+/* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */
+#ifdef CONFIG_REED_SOLOMON_ENC8
+int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
+ uint16_t invmsk);
+#endif
+#ifdef CONFIG_REED_SOLOMON_DEC8
+int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len,
+ uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+ uint16_t *corr);
+#endif
+
+/* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */
+#ifdef CONFIG_REED_SOLOMON_ENC16
+int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
+ uint16_t invmsk);
+#endif
+#ifdef CONFIG_REED_SOLOMON_DEC16
+int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
+ uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+ uint16_t *corr);
+#endif
+
+struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
+ int nroots, gfp_t gfp);
+
+/**
+ * init_rs - Create a RS control struct and initialize it
+ * @symsize: the symbol size (number of bits)
+ * @gfpoly: the extended Galois field generator polynomial coefficients,
+ * with the 0th coefficient in the low order bit. The polynomial
+ * must be primitive;
+ * @fcr: the first consecutive root of the rs code generator polynomial
+ * in index form
+ * @prim: primitive element to generate polynomial roots
+ * @nroots: RS code generator polynomial degree (number of roots)
+ *
+ * Allocations use GFP_KERNEL.
+ */
+static inline struct rs_control *init_rs(int symsize, int gfpoly, int fcr,
+ int prim, int nroots)
+{
+ return init_rs_gfp(symsize, gfpoly, fcr, prim, nroots, GFP_KERNEL);
+}
+
+struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int),
+ int fcr, int prim, int nroots);
+
+/* Release a rs control structure */
+void free_rs(struct rs_control *rs);
+
+/** modulo replacement for galois field arithmetics
+ *
+ * @rs: Pointer to the RS codec
+ * @x: the value to reduce
+ *
+ * where
+ * rs->mm = number of bits per symbol
+ * rs->nn = (2^rs->mm) - 1
+ *
+ * Simple arithmetic modulo would return a wrong result for values
+ * >= 3 * rs->nn
+*/
+static inline int rs_modnn(struct rs_codec *rs, int x)
+{
+ while (x >= rs->nn) {
+ x -= rs->nn;
+ x = (x >> rs->mm) + (x & rs->nn);
+ }
+ return x;
+}
+
+#endif