-/*\r
- * Reed-Solomon ECC handling for the Marvell Kirkwood SOC\r
- * Copyright (C) 2009 Marvell Semiconductor, Inc.\r
- *\r
- * Authors: Lennert Buytenhek <buytenh@wantstofly.org>\r
- * Nicolas Pitre <nico@cam.org>\r
- *\r
- * This file is free software; you can redistribute it and/or modify it\r
- * under the terms of the GNU General Public License as published by the\r
- * Free Software Foundation; either version 2 or (at your option) any\r
- * later version.\r
- *\r
- * This file is distributed in the hope that it will be useful, but WITHOUT\r
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or\r
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License\r
- * for more details.\r
- */\r
-\r
-#ifdef HAVE_CONFIG_H\r
-#include "config.h"\r
-#endif\r
-\r
-#include <sys/types.h>\r
-#include "nand.h"\r
-\r
-\r
-/*****************************************************************************\r
- * Arithmetic in GF(2^10) ("F") modulo x^10 + x^3 + 1.\r
- *\r
- * For multiplication, a discrete log/exponent table is used, with\r
- * primitive element x (F is a primitive field, so x is primitive).\r
- */\r
-#define MODPOLY 0x409 /* x^10 + x^3 + 1 in binary */\r
-\r
-/*\r
- * Maps an integer a [0..1022] to a polynomial b = gf_exp[a] in\r
- * GF(2^10) mod x^10 + x^3 + 1 such that b = x ^ a. There's two\r
- * identical copies of this array back-to-back so that we can save\r
- * the mod 1023 operation when doing a GF multiplication.\r
- */\r
-static uint16_t gf_exp[1023 + 1023];\r
-\r
-/*\r
- * Maps a polynomial b in GF(2^10) mod x^10 + x^3 + 1 to an index\r
- * a = gf_log[b] in [0..1022] such that b = x ^ a.\r
- */\r
-static uint16_t gf_log[1024];\r
-\r
-static void gf_build_log_exp_table(void)\r
-{\r
- int i;\r
- int p_i;\r
-\r
- /*\r
- * p_i = x ^ i\r
- *\r
- * Initialise to 1 for i = 0.\r
- */\r
- p_i = 1;\r
-\r
- for (i = 0; i < 1023; i++) {\r
- gf_exp[i] = p_i;\r
- gf_exp[i + 1023] = p_i;\r
- gf_log[p_i] = i;\r
-\r
- /*\r
- * p_i = p_i * x\r
- */\r
- p_i <<= 1;\r
- if (p_i & (1 << 10))\r
- p_i ^= MODPOLY;\r
- }\r
-}\r
-\r
-\r
-/*****************************************************************************\r
- * Reed-Solomon code\r
- *\r
- * This implements a (1023,1015) Reed-Solomon ECC code over GF(2^10)\r
- * mod x^10 + x^3 + 1, shortened to (520,512). The ECC data consists\r
- * of 8 10-bit symbols, or 10 8-bit bytes.\r
- *\r
- * Given 512 bytes of data, computes 10 bytes of ECC.\r
- *\r
- * This is done by converting the 512 bytes to 512 10-bit symbols\r
- * (elements of F), interpreting those symbols as a polynomial in F[X]\r
- * by taking symbol 0 as the coefficient of X^8 and symbol 511 as the\r
- * coefficient of X^519, and calculating the residue of that polynomial\r
- * divided by the generator polynomial, which gives us the 8 ECC symbols\r
- * as the remainder. Finally, we convert the 8 10-bit ECC symbols to 10\r
- * 8-bit bytes.\r
- *\r
- * The generator polynomial is hardcoded, as that is faster, but it\r
- * can be computed by taking the primitive element a = x (in F), and\r
- * constructing a polynomial in F[X] with roots a, a^2, a^3, ..., a^8\r
- * by multiplying the minimal polynomials for those roots (which are\r
- * just 'x - a^i' for each i).\r
- *\r
- * Note: due to unfortunate circumstances, the bootrom in the Kirkwood SOC\r
- * expects the ECC to be computed backward, i.e. from the last byte down\r
- * to the first one.\r
- */\r
-int nand_calculate_ecc_kw(struct nand_device_s *device, const u8 *data, u8 *ecc)\r
-{\r
- unsigned int r7, r6, r5, r4, r3, r2, r1, r0;\r
- int i;\r
- static int tables_initialized = 0;\r
-\r
- if (!tables_initialized) {\r
- gf_build_log_exp_table();\r
- tables_initialized = 1;\r
- }\r
-\r
- /*\r
- * Load bytes 504..511 of the data into r.\r
- */\r
- r0 = data[504];\r
- r1 = data[505];\r
- r2 = data[506];\r
- r3 = data[507];\r
- r4 = data[508];\r
- r5 = data[509];\r
- r6 = data[510];\r
- r7 = data[511];\r
-\r
-\r
- /*\r
- * Shift bytes 503..0 (in that order) into r0, followed\r
- * by eight zero bytes, while reducing the polynomial by the\r
- * generator polynomial in every step.\r
- */\r
- for (i = 503; i >= -8; i--) {\r
- unsigned int d;\r
-\r
- d = 0;\r
- if (i >= 0)\r
- d = data[i];\r
-\r
- if (r7) {\r
- u16 *t = gf_exp + gf_log[r7];\r
-\r
- r7 = r6 ^ t[0x21c];\r
- r6 = r5 ^ t[0x181];\r
- r5 = r4 ^ t[0x18e];\r
- r4 = r3 ^ t[0x25f];\r
- r3 = r2 ^ t[0x197];\r
- r2 = r1 ^ t[0x193];\r
- r1 = r0 ^ t[0x237];\r
- r0 = d ^ t[0x024];\r
- } else {\r
- r7 = r6;\r
- r6 = r5;\r
- r5 = r4;\r
- r4 = r3;\r
- r3 = r2;\r
- r2 = r1;\r
- r1 = r0;\r
- r0 = d;\r
- }\r
- }\r
-\r
- ecc[0] = r0;\r
- ecc[1] = (r0 >> 8) | (r1 << 2);\r
- ecc[2] = (r1 >> 6) | (r2 << 4);\r
- ecc[3] = (r2 >> 4) | (r3 << 6);\r
- ecc[4] = (r3 >> 2);\r
- ecc[5] = r4;\r
- ecc[6] = (r4 >> 8) | (r5 << 2);\r
- ecc[7] = (r5 >> 6) | (r6 << 4);\r
- ecc[8] = (r6 >> 4) | (r7 << 6);\r
- ecc[9] = (r7 >> 2);\r
-\r
- return 0;\r
-}\r
+/*
+ * Reed-Solomon ECC handling for the Marvell Kirkwood SOC
+ * Copyright (C) 2009 Marvell Semiconductor, Inc.
+ *
+ * Authors: Lennert Buytenhek <buytenh@wantstofly.org>
+ * Nicolas Pitre <nico@cam.org>
+ *
+ * This file is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 or (at your option) any
+ * later version.
+ *
+ * This file is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <sys/types.h>
+#include "nand.h"
+
+
+/*****************************************************************************
+ * Arithmetic in GF(2^10) ("F") modulo x^10 + x^3 + 1.
+ *
+ * For multiplication, a discrete log/exponent table is used, with
+ * primitive element x (F is a primitive field, so x is primitive).
+ */
+#define MODPOLY 0x409 /* x^10 + x^3 + 1 in binary */
+
+/*
+ * Maps an integer a [0..1022] to a polynomial b = gf_exp[a] in
+ * GF(2^10) mod x^10 + x^3 + 1 such that b = x ^ a. There's two
+ * identical copies of this array back-to-back so that we can save
+ * the mod 1023 operation when doing a GF multiplication.
+ */
+static uint16_t gf_exp[1023 + 1023];
+
+/*
+ * Maps a polynomial b in GF(2^10) mod x^10 + x^3 + 1 to an index
+ * a = gf_log[b] in [0..1022] such that b = x ^ a.
+ */
+static uint16_t gf_log[1024];
+
+static void gf_build_log_exp_table(void)
+{
+ int i;
+ int p_i;
+
+ /*
+ * p_i = x ^ i
+ *
+ * Initialise to 1 for i = 0.
+ */
+ p_i = 1;
+
+ for (i = 0; i < 1023; i++) {
+ gf_exp[i] = p_i;
+ gf_exp[i + 1023] = p_i;
+ gf_log[p_i] = i;
+
+ /*
+ * p_i = p_i * x
+ */
+ p_i <<= 1;
+ if (p_i & (1 << 10))
+ p_i ^= MODPOLY;
+ }
+}
+
+
+/*****************************************************************************
+ * Reed-Solomon code
+ *
+ * This implements a (1023,1015) Reed-Solomon ECC code over GF(2^10)
+ * mod x^10 + x^3 + 1, shortened to (520,512). The ECC data consists
+ * of 8 10-bit symbols, or 10 8-bit bytes.
+ *
+ * Given 512 bytes of data, computes 10 bytes of ECC.
+ *
+ * This is done by converting the 512 bytes to 512 10-bit symbols
+ * (elements of F), interpreting those symbols as a polynomial in F[X]
+ * by taking symbol 0 as the coefficient of X^8 and symbol 511 as the
+ * coefficient of X^519, and calculating the residue of that polynomial
+ * divided by the generator polynomial, which gives us the 8 ECC symbols
+ * as the remainder. Finally, we convert the 8 10-bit ECC symbols to 10
+ * 8-bit bytes.
+ *
+ * The generator polynomial is hardcoded, as that is faster, but it
+ * can be computed by taking the primitive element a = x (in F), and
+ * constructing a polynomial in F[X] with roots a, a^2, a^3, ..., a^8
+ * by multiplying the minimal polynomials for those roots (which are
+ * just 'x - a^i' for each i).
+ *
+ * Note: due to unfortunate circumstances, the bootrom in the Kirkwood SOC
+ * expects the ECC to be computed backward, i.e. from the last byte down
+ * to the first one.
+ */
+int nand_calculate_ecc_kw(struct nand_device_s *device, const uint8_t *data, uint8_t *ecc)
+{
+ unsigned int r7, r6, r5, r4, r3, r2, r1, r0;
+ int i;
+ static int tables_initialized = 0;
+
+ if (!tables_initialized) {
+ gf_build_log_exp_table();
+ tables_initialized = 1;
+ }
+
+ /*
+ * Load bytes 504..511 of the data into r.
+ */
+ r0 = data[504];
+ r1 = data[505];
+ r2 = data[506];
+ r3 = data[507];
+ r4 = data[508];
+ r5 = data[509];
+ r6 = data[510];
+ r7 = data[511];
+
+
+ /*
+ * Shift bytes 503..0 (in that order) into r0, followed
+ * by eight zero bytes, while reducing the polynomial by the
+ * generator polynomial in every step.
+ */
+ for (i = 503; i >= -8; i--) {
+ unsigned int d;
+
+ d = 0;
+ if (i >= 0)
+ d = data[i];
+
+ if (r7) {
+ u16 *t = gf_exp + gf_log[r7];
+
+ r7 = r6 ^ t[0x21c];
+ r6 = r5 ^ t[0x181];
+ r5 = r4 ^ t[0x18e];
+ r4 = r3 ^ t[0x25f];
+ r3 = r2 ^ t[0x197];
+ r2 = r1 ^ t[0x193];
+ r1 = r0 ^ t[0x237];
+ r0 = d ^ t[0x024];
+ } else {
+ r7 = r6;
+ r6 = r5;
+ r5 = r4;
+ r4 = r3;
+ r3 = r2;
+ r2 = r1;
+ r1 = r0;
+ r0 = d;
+ }
+ }
+
+ ecc[0] = r0;
+ ecc[1] = (r0 >> 8) | (r1 << 2);
+ ecc[2] = (r1 >> 6) | (r2 << 4);
+ ecc[3] = (r2 >> 4) | (r3 << 6);
+ ecc[4] = (r3 >> 2);
+ ecc[5] = r4;
+ ecc[6] = (r4 >> 8) | (r5 << 2);
+ ecc[7] = (r5 >> 6) | (r6 << 4);
+ ecc[8] = (r6 >> 4) | (r7 << 6);
+ ecc[9] = (r7 >> 2);
+
+ return 0;
+}
Code Review / openocd.git / blobdiff