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-rw-r--r--lib/bch.c174
1 files changed, 104 insertions, 70 deletions
diff --git a/lib/bch.c b/lib/bch.c
index bc89dfe4d1b3..1c0cb07cdfeb 100644
--- a/lib/bch.c
+++ b/lib/bch.c
@@ -23,15 +23,15 @@
* This library provides runtime configurable encoding/decoding of binary
* Bose-Chaudhuri-Hocquenghem (BCH) codes.
*
- * Call init_bch to get a pointer to a newly allocated bch_control structure for
+ * Call bch_init to get a pointer to a newly allocated bch_control structure for
* the given m (Galois field order), t (error correction capability) and
* (optional) primitive polynomial parameters.
*
- * Call encode_bch to compute and store ecc parity bytes to a given buffer.
- * Call decode_bch to detect and locate errors in received data.
+ * Call bch_encode to compute and store ecc parity bytes to a given buffer.
+ * Call bch_decode to detect and locate errors in received data.
*
* On systems supporting hw BCH features, intermediate results may be provided
- * to decode_bch in order to skip certain steps. See decode_bch() documentation
+ * to bch_decode in order to skip certain steps. See bch_decode() documentation
* for details.
*
* Option CONFIG_BCH_CONST_PARAMS can be used to force fixed values of
@@ -71,6 +71,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/bitops.h>
+#include <linux/bitrev.h>
#include <asm/byteorder.h>
#include <linux/bch.h>
@@ -78,15 +79,21 @@
#define GF_M(_p) (CONFIG_BCH_CONST_M)
#define GF_T(_p) (CONFIG_BCH_CONST_T)
#define GF_N(_p) ((1 << (CONFIG_BCH_CONST_M))-1)
+#define BCH_MAX_M (CONFIG_BCH_CONST_M)
+#define BCH_MAX_T (CONFIG_BCH_CONST_T)
#else
#define GF_M(_p) ((_p)->m)
#define GF_T(_p) ((_p)->t)
#define GF_N(_p) ((_p)->n)
+#define BCH_MAX_M 15 /* 2KB */
+#define BCH_MAX_T 64 /* 64 bit correction */
#endif
#define BCH_ECC_WORDS(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 32)
#define BCH_ECC_BYTES(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 8)
+#define BCH_ECC_MAX_WORDS DIV_ROUND_UP(BCH_MAX_M * BCH_MAX_T, 32)
+
#ifndef dbg
#define dbg(_fmt, args...) do {} while (0)
#endif
@@ -96,7 +103,7 @@
*/
struct gf_poly {
unsigned int deg; /* polynomial degree */
- unsigned int c[0]; /* polynomial terms */
+ unsigned int c[]; /* polynomial terms */
};
/* given its degree, compute a polynomial size in bytes */
@@ -108,10 +115,18 @@ struct gf_poly_deg1 {
unsigned int c[2];
};
+static u8 swap_bits(struct bch_control *bch, u8 in)
+{
+ if (!bch->swap_bits)
+ return in;
+
+ return bitrev8(in);
+}
+
/*
- * same as encode_bch(), but process input data one byte at a time
+ * same as bch_encode(), but process input data one byte at a time
*/
-static void encode_bch_unaligned(struct bch_control *bch,
+static void bch_encode_unaligned(struct bch_control *bch,
const unsigned char *data, unsigned int len,
uint32_t *ecc)
{
@@ -120,7 +135,9 @@ static void encode_bch_unaligned(struct bch_control *bch,
const int l = BCH_ECC_WORDS(bch)-1;
while (len--) {
- p = bch->mod8_tab + (l+1)*(((ecc[0] >> 24)^(*data++)) & 0xff);
+ u8 tmp = swap_bits(bch, *data++);
+
+ p = bch->mod8_tab + (l+1)*(((ecc[0] >> 24)^(tmp)) & 0xff);
for (i = 0; i < l; i++)
ecc[i] = ((ecc[i] << 8)|(ecc[i+1] >> 24))^(*p++);
@@ -139,10 +156,16 @@ static void load_ecc8(struct bch_control *bch, uint32_t *dst,
unsigned int i, nwords = BCH_ECC_WORDS(bch)-1;
for (i = 0; i < nwords; i++, src += 4)
- dst[i] = (src[0] << 24)|(src[1] << 16)|(src[2] << 8)|src[3];
+ dst[i] = ((u32)swap_bits(bch, src[0]) << 24) |
+ ((u32)swap_bits(bch, src[1]) << 16) |
+ ((u32)swap_bits(bch, src[2]) << 8) |
+ swap_bits(bch, src[3]);
memcpy(pad, src, BCH_ECC_BYTES(bch)-4*nwords);
- dst[nwords] = (pad[0] << 24)|(pad[1] << 16)|(pad[2] << 8)|pad[3];
+ dst[nwords] = ((u32)swap_bits(bch, pad[0]) << 24) |
+ ((u32)swap_bits(bch, pad[1]) << 16) |
+ ((u32)swap_bits(bch, pad[2]) << 8) |
+ swap_bits(bch, pad[3]);
}
/*
@@ -155,20 +178,20 @@ static void store_ecc8(struct bch_control *bch, uint8_t *dst,
unsigned int i, nwords = BCH_ECC_WORDS(bch)-1;
for (i = 0; i < nwords; i++) {
- *dst++ = (src[i] >> 24);
- *dst++ = (src[i] >> 16) & 0xff;
- *dst++ = (src[i] >> 8) & 0xff;
- *dst++ = (src[i] >> 0) & 0xff;
+ *dst++ = swap_bits(bch, src[i] >> 24);
+ *dst++ = swap_bits(bch, src[i] >> 16);
+ *dst++ = swap_bits(bch, src[i] >> 8);
+ *dst++ = swap_bits(bch, src[i]);
}
- pad[0] = (src[nwords] >> 24);
- pad[1] = (src[nwords] >> 16) & 0xff;
- pad[2] = (src[nwords] >> 8) & 0xff;
- pad[3] = (src[nwords] >> 0) & 0xff;
+ pad[0] = swap_bits(bch, src[nwords] >> 24);
+ pad[1] = swap_bits(bch, src[nwords] >> 16);
+ pad[2] = swap_bits(bch, src[nwords] >> 8);
+ pad[3] = swap_bits(bch, src[nwords]);
memcpy(dst, pad, BCH_ECC_BYTES(bch)-4*nwords);
}
/**
- * encode_bch - calculate BCH ecc parity of data
+ * bch_encode - calculate BCH ecc parity of data
* @bch: BCH control structure
* @data: data to encode
* @len: data length in bytes
@@ -181,31 +204,35 @@ static void store_ecc8(struct bch_control *bch, uint8_t *dst,
* The exact number of computed ecc parity bits is given by member @ecc_bits of
* @bch; it may be less than m*t for large values of t.
*/
-void encode_bch(struct bch_control *bch, const uint8_t *data,
+void bch_encode(struct bch_control *bch, const uint8_t *data,
unsigned int len, uint8_t *ecc)
{
const unsigned int l = BCH_ECC_WORDS(bch)-1;
unsigned int i, mlen;
unsigned long m;
- uint32_t w, r[l+1];
+ uint32_t w, r[BCH_ECC_MAX_WORDS];
+ const size_t r_bytes = BCH_ECC_WORDS(bch) * sizeof(*r);
const uint32_t * const tab0 = bch->mod8_tab;
const uint32_t * const tab1 = tab0 + 256*(l+1);
const uint32_t * const tab2 = tab1 + 256*(l+1);
const uint32_t * const tab3 = tab2 + 256*(l+1);
const uint32_t *pdata, *p0, *p1, *p2, *p3;
+ if (WARN_ON(r_bytes > sizeof(r)))
+ return;
+
if (ecc) {
/* load ecc parity bytes into internal 32-bit buffer */
load_ecc8(bch, bch->ecc_buf, ecc);
} else {
- memset(bch->ecc_buf, 0, sizeof(r));
+ memset(bch->ecc_buf, 0, r_bytes);
}
/* process first unaligned data bytes */
m = ((unsigned long)data) & 3;
if (m) {
mlen = (len < (4-m)) ? len : 4-m;
- encode_bch_unaligned(bch, data, mlen, bch->ecc_buf);
+ bch_encode_unaligned(bch, data, mlen, bch->ecc_buf);
data += mlen;
len -= mlen;
}
@@ -215,7 +242,7 @@ void encode_bch(struct bch_control *bch, const uint8_t *data,
mlen = len/4;
data += 4*mlen;
len -= 4*mlen;
- memcpy(r, bch->ecc_buf, sizeof(r));
+ memcpy(r, bch->ecc_buf, r_bytes);
/*
* split each 32-bit word into 4 polynomials of weight 8 as follows:
@@ -230,7 +257,13 @@ void encode_bch(struct bch_control *bch, const uint8_t *data,
*/
while (mlen--) {
/* input data is read in big-endian format */
- w = r[0]^cpu_to_be32(*pdata++);
+ w = cpu_to_be32(*pdata++);
+ if (bch->swap_bits)
+ w = (u32)swap_bits(bch, w) |
+ ((u32)swap_bits(bch, w >> 8) << 8) |
+ ((u32)swap_bits(bch, w >> 16) << 16) |
+ ((u32)swap_bits(bch, w >> 24) << 24);
+ w ^= r[0];
p0 = tab0 + (l+1)*((w >> 0) & 0xff);
p1 = tab1 + (l+1)*((w >> 8) & 0xff);
p2 = tab2 + (l+1)*((w >> 16) & 0xff);
@@ -241,17 +274,17 @@ void encode_bch(struct bch_control *bch, const uint8_t *data,
r[l] = p0[l]^p1[l]^p2[l]^p3[l];
}
- memcpy(bch->ecc_buf, r, sizeof(r));
+ memcpy(bch->ecc_buf, r, r_bytes);
/* process last unaligned bytes */
if (len)
- encode_bch_unaligned(bch, data, len, bch->ecc_buf);
+ bch_encode_unaligned(bch, data, len, bch->ecc_buf);
/* store ecc parity bytes into original parity buffer */
if (ecc)
store_ecc8(bch, ecc, bch->ecc_buf);
}
-EXPORT_SYMBOL_GPL(encode_bch);
+EXPORT_SYMBOL_GPL(bch_encode);
static inline int modulo(struct bch_control *bch, unsigned int v)
{
@@ -434,7 +467,7 @@ static int solve_linear_system(struct bch_control *bch, unsigned int *rows,
{
const int m = GF_M(bch);
unsigned int tmp, mask;
- int rem, c, r, p, k, param[m];
+ int rem, c, r, p, k, param[BCH_MAX_M];
k = 0;
mask = 1 << m;
@@ -446,11 +479,8 @@ static int solve_linear_system(struct bch_control *bch, unsigned int *rows,
/* find suitable row for elimination */
for (r = p; r < m; r++) {
if (rows[r] & mask) {
- if (r != p) {
- tmp = rows[r];
- rows[r] = rows[p];
- rows[p] = tmp;
- }
+ if (r != p)
+ swap(rows[r], rows[p]);
rem = r+1;
break;
}
@@ -517,7 +547,7 @@ static int find_affine4_roots(struct bch_control *bch, unsigned int a,
k = a_log(bch, a);
rows[0] = c;
- /* buid linear system to solve X^4+aX^2+bX+c = 0 */
+ /* build linear system to solve X^4+aX^2+bX+c = 0 */
for (i = 0; i < m; i++) {
rows[i+1] = bch->a_pow_tab[4*i]^
(a ? bch->a_pow_tab[mod_s(bch, k)] : 0)^
@@ -766,21 +796,14 @@ static void gf_poly_div(struct bch_control *bch, struct gf_poly *a,
static struct gf_poly *gf_poly_gcd(struct bch_control *bch, struct gf_poly *a,
struct gf_poly *b)
{
- struct gf_poly *tmp;
-
dbg("gcd(%s,%s)=", gf_poly_str(a), gf_poly_str(b));
- if (a->deg < b->deg) {
- tmp = b;
- b = a;
- a = tmp;
- }
+ if (a->deg < b->deg)
+ swap(a, b);
while (b->deg > 0) {
gf_poly_mod(bch, a, b, NULL);
- tmp = b;
- b = a;
- a = tmp;
+ swap(a, b);
}
dbg("%s\n", gf_poly_str(a));
@@ -942,7 +965,7 @@ static int chien_search(struct bch_control *bch, unsigned int len,
#endif /* USE_CHIEN_SEARCH */
/**
- * decode_bch - decode received codeword and find bit error locations
+ * bch_decode - decode received codeword and find bit error locations
* @bch: BCH control structure
* @data: received data, ignored if @calc_ecc is provided
* @len: data length in bytes, must always be provided
@@ -956,22 +979,22 @@ static int chien_search(struct bch_control *bch, unsigned int len,
* invalid parameters were provided
*
* Depending on the available hw BCH support and the need to compute @calc_ecc
- * separately (using encode_bch()), this function should be called with one of
+ * separately (using bch_encode()), this function should be called with one of
* the following parameter configurations -
*
* by providing @data and @recv_ecc only:
- * decode_bch(@bch, @data, @len, @recv_ecc, NULL, NULL, @errloc)
+ * bch_decode(@bch, @data, @len, @recv_ecc, NULL, NULL, @errloc)
*
* by providing @recv_ecc and @calc_ecc:
- * decode_bch(@bch, NULL, @len, @recv_ecc, @calc_ecc, NULL, @errloc)
+ * bch_decode(@bch, NULL, @len, @recv_ecc, @calc_ecc, NULL, @errloc)
*
* by providing ecc = recv_ecc XOR calc_ecc:
- * decode_bch(@bch, NULL, @len, NULL, ecc, NULL, @errloc)
+ * bch_decode(@bch, NULL, @len, NULL, ecc, NULL, @errloc)
*
* by providing syndrome results @syn:
- * decode_bch(@bch, NULL, @len, NULL, NULL, @syn, @errloc)
+ * bch_decode(@bch, NULL, @len, NULL, NULL, @syn, @errloc)
*
- * Once decode_bch() has successfully returned with a positive value, error
+ * Once bch_decode() has successfully returned with a positive value, error
* locations returned in array @errloc should be interpreted as follows -
*
* if (errloc[n] >= 8*len), then n-th error is located in ecc (no need for
@@ -983,7 +1006,7 @@ static int chien_search(struct bch_control *bch, unsigned int len,
* Note that this function does not perform any data correction by itself, it
* merely indicates error locations.
*/
-int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
+int bch_decode(struct bch_control *bch, const uint8_t *data, unsigned int len,
const uint8_t *recv_ecc, const uint8_t *calc_ecc,
const unsigned int *syn, unsigned int *errloc)
{
@@ -1002,7 +1025,7 @@ int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
/* compute received data ecc into an internal buffer */
if (!data || !recv_ecc)
return -EINVAL;
- encode_bch(bch, data, len, NULL);
+ bch_encode(bch, data, len, NULL);
} else {
/* load provided calculated ecc */
load_ecc8(bch, bch->ecc_buf, calc_ecc);
@@ -1038,12 +1061,14 @@ int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
break;
}
errloc[i] = nbits-1-errloc[i];
- errloc[i] = (errloc[i] & ~7)|(7-(errloc[i] & 7));
+ if (!bch->swap_bits)
+ errloc[i] = (errloc[i] & ~7) |
+ (7-(errloc[i] & 7));
}
}
return (err >= 0) ? err : -EBADMSG;
}
-EXPORT_SYMBOL_GPL(decode_bch);
+EXPORT_SYMBOL_GPL(bch_decode);
/*
* generate Galois field lookup tables
@@ -1114,7 +1139,7 @@ static int build_deg2_base(struct bch_control *bch)
{
const int m = GF_M(bch);
int i, j, r;
- unsigned int sum, x, y, remaining, ak = 0, xi[m];
+ unsigned int sum, x, y, remaining, ak = 0, xi[BCH_MAX_M];
/* find k s.t. Tr(a^k) = 1 and 0 <= k < m */
for (i = 0; i < m; i++) {
@@ -1226,27 +1251,29 @@ finish:
}
/**
- * init_bch - initialize a BCH encoder/decoder
+ * bch_init - initialize a BCH encoder/decoder
* @m: Galois field order, should be in the range 5-15
* @t: maximum error correction capability, in bits
* @prim_poly: user-provided primitive polynomial (or 0 to use default)
+ * @swap_bits: swap bits within data and syndrome bytes
*
* Returns:
* a newly allocated BCH control structure if successful, NULL otherwise
*
* This initialization can take some time, as lookup tables are built for fast
* encoding/decoding; make sure not to call this function from a time critical
- * path. Usually, init_bch() should be called on module/driver init and
- * free_bch() should be called to release memory on exit.
+ * path. Usually, bch_init() should be called on module/driver init and
+ * bch_free() should be called to release memory on exit.
*
* You may provide your own primitive polynomial of degree @m in argument
- * @prim_poly, or let init_bch() use its default polynomial.
+ * @prim_poly, or let bch_init() use its default polynomial.
*
- * Once init_bch() has successfully returned a pointer to a newly allocated
+ * Once bch_init() has successfully returned a pointer to a newly allocated
* BCH control structure, ecc length in bytes is given by member @ecc_bytes of
* the structure.
*/
-struct bch_control *init_bch(int m, int t, unsigned int prim_poly)
+struct bch_control *bch_init(int m, int t, unsigned int prim_poly,
+ bool swap_bits)
{
int err = 0;
unsigned int i, words;
@@ -1254,7 +1281,6 @@ struct bch_control *init_bch(int m, int t, unsigned int prim_poly)
struct bch_control *bch = NULL;
const int min_m = 5;
- const int max_m = 15;
/* default primitive polynomials */
static const unsigned int prim_poly_tab[] = {
@@ -1270,7 +1296,7 @@ struct bch_control *init_bch(int m, int t, unsigned int prim_poly)
goto fail;
}
#endif
- if ((m < min_m) || (m > max_m))
+ if ((m < min_m) || (m > BCH_MAX_M))
/*
* values of m greater than 15 are not currently supported;
* supporting m > 15 would require changing table base type
@@ -1278,6 +1304,13 @@ struct bch_control *init_bch(int m, int t, unsigned int prim_poly)
*/
goto fail;
+ if (t > BCH_MAX_T)
+ /*
+ * we can support larger than 64 bits if necessary, at the
+ * cost of higher stack usage.
+ */
+ goto fail;
+
/* sanity checks */
if ((t < 1) || (m*t >= ((1 << m)-1)))
/* invalid t value */
@@ -1305,6 +1338,7 @@ struct bch_control *init_bch(int m, int t, unsigned int prim_poly)
bch->syn = bch_alloc(2*t*sizeof(*bch->syn), &err);
bch->cache = bch_alloc(2*t*sizeof(*bch->cache), &err);
bch->elp = bch_alloc((t+1)*sizeof(struct gf_poly_deg1), &err);
+ bch->swap_bits = swap_bits;
for (i = 0; i < ARRAY_SIZE(bch->poly_2t); i++)
bch->poly_2t[i] = bch_alloc(GF_POLY_SZ(2*t), &err);
@@ -1331,16 +1365,16 @@ struct bch_control *init_bch(int m, int t, unsigned int prim_poly)
return bch;
fail:
- free_bch(bch);
+ bch_free(bch);
return NULL;
}
-EXPORT_SYMBOL_GPL(init_bch);
+EXPORT_SYMBOL_GPL(bch_init);
/**
- * free_bch - free the BCH control structure
+ * bch_free - free the BCH control structure
* @bch: BCH control structure to release
*/
-void free_bch(struct bch_control *bch)
+void bch_free(struct bch_control *bch)
{
unsigned int i;
@@ -1361,7 +1395,7 @@ void free_bch(struct bch_control *bch)
kfree(bch);
}
}
-EXPORT_SYMBOL_GPL(free_bch);
+EXPORT_SYMBOL_GPL(bch_free);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ivan Djelic <ivan.djelic@parrot.com>");
generated by cgit (git 2.34.1) at 2025-12-21 21:11:39 +0000