+// SPDX-License-Identifier: GPL-2.0-or-later WITH eCos-exception-2.0
+
/*
* This file contains an ECC algorithm from Toshiba that allows for detection
* and correction of 1-bit errors in a 256 byte block of data.
* Toshiba America Electronics Components, Inc.
*
* Copyright (C) 2006 Thomas Gleixner <tglx at linutronix.de>
- *
- * 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.
- *
- * You should have received a copy of the GNU General Public License along
- * with this file; if not, write to the Free Software Foundation, Inc.,
- * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
- *
- * As a special exception, if other files instantiate templates or use
- * macros or inline functions from these files, or you compile these
- * files and link them with other works to produce a work based on these
- * files, these files do not by themselves cause the resulting work to be
- * covered by the GNU General Public License. However the source code for
- * these files must still be made available in accordance with section (3)
- * of the GNU General Public License.
- *
- * This exception does not invalidate any other reasons why a work based on
- * this file might be covered by the GNU General Public License.
*/
#ifdef HAVE_CONFIG_H
return 0;
}
+
+static inline int countbits(uint32_t b)
+{
+ int res = 0;
+
+ for (; b; b >>= 1)
+ res += b & 0x01;
+ return res;
+}
+
+/**
+ * nand_correct_data - Detect and correct a 1 bit error for 256 byte block
+ */
+int nand_correct_data(struct nand_device *nand, u_char *dat,
+ u_char *read_ecc, u_char *calc_ecc)
+{
+ uint8_t s0, s1, s2;
+
+#ifdef NAND_ECC_SMC
+ s0 = calc_ecc[0] ^ read_ecc[0];
+ s1 = calc_ecc[1] ^ read_ecc[1];
+ s2 = calc_ecc[2] ^ read_ecc[2];
+#else
+ s1 = calc_ecc[0] ^ read_ecc[0];
+ s0 = calc_ecc[1] ^ read_ecc[1];
+ s2 = calc_ecc[2] ^ read_ecc[2];
+#endif
+ if ((s0 | s1 | s2) == 0)
+ return 0;
+
+ /* Check for a single bit error */
+ if (((s0 ^ (s0 >> 1)) & 0x55) == 0x55 &&
+ ((s1 ^ (s1 >> 1)) & 0x55) == 0x55 &&
+ ((s2 ^ (s2 >> 1)) & 0x54) == 0x54) {
+
+ uint32_t byteoffs, bitnum;
+
+ byteoffs = (s1 << 0) & 0x80;
+ byteoffs |= (s1 << 1) & 0x40;
+ byteoffs |= (s1 << 2) & 0x20;
+ byteoffs |= (s1 << 3) & 0x10;
+
+ byteoffs |= (s0 >> 4) & 0x08;
+ byteoffs |= (s0 >> 3) & 0x04;
+ byteoffs |= (s0 >> 2) & 0x02;
+ byteoffs |= (s0 >> 1) & 0x01;
+
+ bitnum = (s2 >> 5) & 0x04;
+ bitnum |= (s2 >> 4) & 0x02;
+ bitnum |= (s2 >> 3) & 0x01;
+
+ dat[byteoffs] ^= (1 << bitnum);
+
+ return 1;
+ }
+
+ if (countbits(s0 | ((uint32_t)s1 << 8) | ((uint32_t)s2 << 16)) == 1)
+ return 1;
+
+ return -1;
+}