Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 424 insertions, 0 deletions

diff --git a/lib/reed_solomon/reed_solomon.c b/lib/reed_solomon/reed_solomon.c
new file mode 100644
index 000000000..bbc01bad3
--- /dev/null
+++ b/lib/reed_solomon/reed_solomon.c
@@ -0,0 +1,424 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Reed Solomon encoder / decoder library
+ *
+ * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
+ *
+ * Reed Solomon code lifted from reed solomon library written by Phil Karn
+ * Copyright 2002 Phil Karn, KA9Q
+ *
+ * Description:
+ *
+ * The generic Reed Solomon library provides runtime configurable
+ * encoding / decoding of RS codes.
+ *
+ * Each user must call init_rs to get a pointer to a rs_control structure
+ * for the given rs parameters. The control struct is unique per instance.
+ * It points to a codec which can be shared by multiple control structures.
+ * If a codec is newly allocated then the polynomial arrays for fast
+ * encoding / decoding are built. This can take some time so make sure not
+ * to call this function from a time critical path.  Usually a module /
+ * driver should initialize the necessary rs_control structure on module /
+ * driver init and release it on exit.
+ *
+ * The encoding puts the calculated syndrome into a given syndrome buffer.
+ *
+ * The decoding is a two step process. The first step calculates the
+ * syndrome over the received (data + syndrome) and calls the second stage,
+ * which does the decoding / error correction itself.  Many hw encoders
+ * provide a syndrome calculation over the received data + syndrome and can
+ * call the second stage directly.
+ */
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/rslib.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+
+enum {
+	RS_DECODE_LAMBDA,
+	RS_DECODE_SYN,
+	RS_DECODE_B,
+	RS_DECODE_T,
+	RS_DECODE_OMEGA,
+	RS_DECODE_ROOT,
+	RS_DECODE_REG,
+	RS_DECODE_LOC,
+	RS_DECODE_NUM_BUFFERS
+};
+
+/* This list holds all currently allocated rs codec structures */
+static LIST_HEAD(codec_list);
+/* Protection for the list */
+static DEFINE_MUTEX(rslistlock);
+
+/**
+ * codec_init - Initialize a Reed-Solomon codec
+ * @symsize:	symbol size, bits (1-8)
+ * @gfpoly:	Field generator polynomial coefficients
+ * @gffunc:	Field generator function
+ * @fcr:	first root of RS code generator polynomial, index form
+ * @prim:	primitive element to generate polynomial roots
+ * @nroots:	RS code generator polynomial degree (number of roots)
+ * @gfp:	GFP_ flags for allocations
+ *
+ * Allocate a codec structure and the polynom arrays for faster
+ * en/decoding. Fill the arrays according to the given parameters.
+ */
+static struct rs_codec *codec_init(int symsize, int gfpoly, int (*gffunc)(int),
+				   int fcr, int prim, int nroots, gfp_t gfp)
+{
+	int i, j, sr, root, iprim;
+	struct rs_codec *rs;
+
+	rs = kzalloc(sizeof(*rs), gfp);
+	if (!rs)
+		return NULL;
+
+	INIT_LIST_HEAD(&rs->list);
+
+	rs->mm = symsize;
+	rs->nn = (1 << symsize) - 1;
+	rs->fcr = fcr;
+	rs->prim = prim;
+	rs->nroots = nroots;
+	rs->gfpoly = gfpoly;
+	rs->gffunc = gffunc;
+
+	/* Allocate the arrays */
+	rs->alpha_to = kmalloc_array(rs->nn + 1, sizeof(uint16_t), gfp);
+	if (rs->alpha_to == NULL)
+		goto err;
+
+	rs->index_of = kmalloc_array(rs->nn + 1, sizeof(uint16_t), gfp);
+	if (rs->index_of == NULL)
+		goto err;
+
+	rs->genpoly = kmalloc_array(rs->nroots + 1, sizeof(uint16_t), gfp);
+	if(rs->genpoly == NULL)
+		goto err;
+
+	/* Generate Galois field lookup tables */
+	rs->index_of[0] = rs->nn;	/* log(zero) = -inf */
+	rs->alpha_to[rs->nn] = 0;	/* alpha**-inf = 0 */
+	if (gfpoly) {
+		sr = 1;
+		for (i = 0; i < rs->nn; i++) {
+			rs->index_of[sr] = i;
+			rs->alpha_to[i] = sr;
+			sr <<= 1;
+			if (sr & (1 << symsize))
+				sr ^= gfpoly;
+			sr &= rs->nn;
+		}
+	} else {
+		sr = gffunc(0);
+		for (i = 0; i < rs->nn; i++) {
+			rs->index_of[sr] = i;
+			rs->alpha_to[i] = sr;
+			sr = gffunc(sr);
+		}
+	}
+	/* If it's not primitive, exit */
+	if(sr != rs->alpha_to[0])
+		goto err;
+
+	/* Find prim-th root of 1, used in decoding */
+	for(iprim = 1; (iprim % prim) != 0; iprim += rs->nn);
+	/* prim-th root of 1, index form */
+	rs->iprim = iprim / prim;
+
+	/* Form RS code generator polynomial from its roots */
+	rs->genpoly[0] = 1;
+	for (i = 0, root = fcr * prim; i < nroots; i++, root += prim) {
+		rs->genpoly[i + 1] = 1;
+		/* Multiply rs->genpoly[] by  @**(root + x) */
+		for (j = i; j > 0; j--) {
+			if (rs->genpoly[j] != 0) {
+				rs->genpoly[j] = rs->genpoly[j -1] ^
+					rs->alpha_to[rs_modnn(rs,
+					rs->index_of[rs->genpoly[j]] + root)];
+			} else
+				rs->genpoly[j] = rs->genpoly[j - 1];
+		}
+		/* rs->genpoly[0] can never be zero */
+		rs->genpoly[0] =
+			rs->alpha_to[rs_modnn(rs,
+				rs->index_of[rs->genpoly[0]] + root)];
+	}
+	/* convert rs->genpoly[] to index form for quicker encoding */
+	for (i = 0; i <= nroots; i++)
+		rs->genpoly[i] = rs->index_of[rs->genpoly[i]];
+
+	rs->users = 1;
+	list_add(&rs->list, &codec_list);
+	return rs;
+
+err:
+	kfree(rs->genpoly);
+	kfree(rs->index_of);
+	kfree(rs->alpha_to);
+	kfree(rs);
+	return NULL;
+}
+
+
+/**
+ *  free_rs - Free the rs control structure
+ *  @rs:	The control structure which is not longer used by the
+ *		caller
+ *
+ * Free the control structure. If @rs is the last user of the associated
+ * codec, free the codec as well.
+ */
+void free_rs(struct rs_control *rs)
+{
+	struct rs_codec *cd;
+
+	if (!rs)
+		return;
+
+	cd = rs->codec;
+	mutex_lock(&rslistlock);
+	cd->users--;
+	if(!cd->users) {
+		list_del(&cd->list);
+		kfree(cd->alpha_to);
+		kfree(cd->index_of);
+		kfree(cd->genpoly);
+		kfree(cd);
+	}
+	mutex_unlock(&rslistlock);
+	kfree(rs);
+}
+EXPORT_SYMBOL_GPL(free_rs);
+
+/**
+ * init_rs_internal - Allocate rs control, find a matching codec or allocate a new one
+ *  @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;
+ *  @gffunc:	pointer to function to generate the next field element,
+ *		or the multiplicative identity element if given 0.  Used
+ *		instead of gfpoly if gfpoly is 0
+ *  @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)
+ *  @gfp:	GFP_ flags for allocations
+ */
+static struct rs_control *init_rs_internal(int symsize, int gfpoly,
+					   int (*gffunc)(int), int fcr,
+					   int prim, int nroots, gfp_t gfp)
+{
+	struct list_head *tmp;
+	struct rs_control *rs;
+	unsigned int bsize;
+
+	/* Sanity checks */
+	if (symsize < 1)
+		return NULL;
+	if (fcr < 0 || fcr >= (1<<symsize))
+		return NULL;
+	if (prim <= 0 || prim >= (1<<symsize))
+		return NULL;
+	if (nroots < 0 || nroots >= (1<<symsize))
+		return NULL;
+
+	/*
+	 * The decoder needs buffers in each control struct instance to
+	 * avoid variable size or large fixed size allocations on
+	 * stack. Size the buffers to arrays of [nroots + 1].
+	 */
+	bsize = sizeof(uint16_t) * RS_DECODE_NUM_BUFFERS * (nroots + 1);
+	rs = kzalloc(sizeof(*rs) + bsize, gfp);
+	if (!rs)
+		return NULL;
+
+	mutex_lock(&rslistlock);
+
+	/* Walk through the list and look for a matching entry */
+	list_for_each(tmp, &codec_list) {
+		struct rs_codec *cd = list_entry(tmp, struct rs_codec, list);
+
+		if (symsize != cd->mm)
+			continue;
+		if (gfpoly != cd->gfpoly)
+			continue;
+		if (gffunc != cd->gffunc)
+			continue;
+		if (fcr != cd->fcr)
+			continue;
+		if (prim != cd->prim)
+			continue;
+		if (nroots != cd->nroots)
+			continue;
+		/* We have a matching one already */
+		cd->users++;
+		rs->codec = cd;
+		goto out;
+	}
+
+	/* Create a new one */
+	rs->codec = codec_init(symsize, gfpoly, gffunc, fcr, prim, nroots, gfp);
+	if (!rs->codec) {
+		kfree(rs);
+		rs = NULL;
+	}
+out:
+	mutex_unlock(&rslistlock);
+	return rs;
+}
+
+/**
+ * init_rs_gfp - 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)
+ *  @gfp:	Memory allocation flags.
+ */
+struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
+			       int nroots, gfp_t gfp)
+{
+	return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots, gfp);
+}
+EXPORT_SYMBOL_GPL(init_rs_gfp);
+
+/**
+ * init_rs_non_canonical - Allocate rs control struct for fields with
+ *                         non-canonical representation
+ *  @symsize:	the symbol size (number of bits)
+ *  @gffunc:	pointer to function to generate the next field element,
+ *		or the multiplicative identity element if given 0.  Used
+ *		instead of gfpoly if gfpoly is 0
+ *  @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)
+ */
+struct rs_control *init_rs_non_canonical(int symsize, int (*gffunc)(int),
+					 int fcr, int prim, int nroots)
+{
+	return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots,
+				GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(init_rs_non_canonical);
+
+#ifdef CONFIG_REED_SOLOMON_ENC8
+/**
+ *  encode_rs8 - Calculate the parity for data values (8bit data width)
+ *  @rsc:	the rs control structure
+ *  @data:	data field of a given type
+ *  @len:	data length
+ *  @par:	parity data, must be initialized by caller (usually all 0)
+ *  @invmsk:	invert data mask (will be xored on data)
+ *
+ *  The parity uses a uint16_t data type to enable
+ *  symbol size > 8. The calling code must take care of encoding of the
+ *  syndrome result for storage itself.
+ */
+int encode_rs8(struct rs_control *rsc, uint8_t *data, int len, uint16_t *par,
+	       uint16_t invmsk)
+{
+#include "encode_rs.c"
+}
+EXPORT_SYMBOL_GPL(encode_rs8);
+#endif
+
+#ifdef CONFIG_REED_SOLOMON_DEC8
+/**
+ *  decode_rs8 - Decode codeword (8bit data width)
+ *  @rsc:	the rs control structure
+ *  @data:	data field of a given type
+ *  @par:	received parity data field
+ *  @len:	data length
+ *  @s: 	syndrome data field, must be in index form
+ *		(if NULL, syndrome is calculated)
+ *  @no_eras:	number of erasures
+ *  @eras_pos:	position of erasures, can be NULL
+ *  @invmsk:	invert data mask (will be xored on data, not on parity!)
+ *  @corr:	buffer to store correction bitmask on eras_pos
+ *
+ *  The syndrome and parity uses a uint16_t data type to enable
+ *  symbol size > 8. The calling code must take care of decoding of the
+ *  syndrome result and the received parity before calling this code.
+ *
+ *  Note: The rs_control struct @rsc contains buffers which are used for
+ *  decoding, so the caller has to ensure that decoder invocations are
+ *  serialized.
+ *
+ *  Returns the number of corrected symbols or -EBADMSG for uncorrectable
+ *  errors. The count includes errors in the parity.
+ */
+int decode_rs8(struct rs_control *rsc, uint8_t *data, uint16_t *par, int len,
+	       uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+	       uint16_t *corr)
+{
+#include "decode_rs.c"
+}
+EXPORT_SYMBOL_GPL(decode_rs8);
+#endif
+
+#ifdef CONFIG_REED_SOLOMON_ENC16
+/**
+ *  encode_rs16 - Calculate the parity for data values (16bit data width)
+ *  @rsc:	the rs control structure
+ *  @data:	data field of a given type
+ *  @len:	data length
+ *  @par:	parity data, must be initialized by caller (usually all 0)
+ *  @invmsk:	invert data mask (will be xored on data, not on parity!)
+ *
+ *  Each field in the data array contains up to symbol size bits of valid data.
+ */
+int encode_rs16(struct rs_control *rsc, uint16_t *data, int len, uint16_t *par,
+	uint16_t invmsk)
+{
+#include "encode_rs.c"
+}
+EXPORT_SYMBOL_GPL(encode_rs16);
+#endif
+
+#ifdef CONFIG_REED_SOLOMON_DEC16
+/**
+ *  decode_rs16 - Decode codeword (16bit data width)
+ *  @rsc:	the rs control structure
+ *  @data:	data field of a given type
+ *  @par:	received parity data field
+ *  @len:	data length
+ *  @s: 	syndrome data field, must be in index form
+ *		(if NULL, syndrome is calculated)
+ *  @no_eras:	number of erasures
+ *  @eras_pos:	position of erasures, can be NULL
+ *  @invmsk:	invert data mask (will be xored on data, not on parity!)
+ *  @corr:	buffer to store correction bitmask on eras_pos
+ *
+ *  Each field in the data array contains up to symbol size bits of valid data.
+ *
+ *  Note: The rc_control struct @rsc contains buffers which are used for
+ *  decoding, so the caller has to ensure that decoder invocations are
+ *  serialized.
+ *
+ *  Returns the number of corrected symbols or -EBADMSG for uncorrectable
+ *  errors. The count includes errors in the parity.
+ */
+int decode_rs16(struct rs_control *rsc, uint16_t *data, uint16_t *par, int len,
+		uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+		uint16_t *corr)
+{
+#include "decode_rs.c"
+}
+EXPORT_SYMBOL_GPL(decode_rs16);
+#endif
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Reed Solomon encoder/decoder");
+MODULE_AUTHOR("Phil Karn, Thomas Gleixner");
+