| #include <linux/mtd/zftl_ecc.h> |
| #include <linux/bitops.h> |
| |
| |
| |
| static const unsigned char column_parity_table[] = { |
| 0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69, |
| 0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00, |
| 0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc, |
| 0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95, |
| 0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0, |
| 0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99, |
| 0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65, |
| 0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c, |
| 0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc, |
| 0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5, |
| 0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59, |
| 0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30, |
| 0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55, |
| 0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c, |
| 0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0, |
| 0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9, |
| 0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0, |
| 0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9, |
| 0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55, |
| 0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c, |
| 0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59, |
| 0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30, |
| 0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc, |
| 0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5, |
| 0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65, |
| 0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c, |
| 0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0, |
| 0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99, |
| 0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc, |
| 0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95, |
| 0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69, |
| 0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00, |
| }; |
| |
| |
| void zftl_ecc_calc_other(const unsigned char *data, unsigned n_bytes, |
| struct zftl_ecc_other *ecc_other) |
| { |
| unsigned int i; |
| |
| unsigned char col_parity = 0; |
| unsigned line_parity = 0; |
| unsigned line_parity_prime = 0; |
| unsigned char b; |
| |
| for (i = 0; i < n_bytes; i++) { |
| b = column_parity_table[*data++]; |
| col_parity ^= b; |
| |
| if (b & 0x01) { |
| /* odd number of bits in the byte */ |
| line_parity ^= i; |
| line_parity_prime ^= ~i; |
| } |
| |
| } |
| |
| ecc_other->col_parity = (col_parity >> 2) & 0x3f; |
| ecc_other->line_parity = line_parity; |
| ecc_other->line_parity_prime = line_parity_prime; |
| } |
| |
| int zftl_ecc_correct_other(unsigned char *data, unsigned n_bytes, |
| struct zftl_ecc_other *read_ecc, |
| const struct zftl_ecc_other *test_ecc) |
| { |
| unsigned char delta_col; /* column parity delta */ |
| unsigned delta_line; /* line parity delta */ |
| unsigned delta_line_prime; /* line parity delta */ |
| unsigned bit; |
| |
| delta_col = read_ecc->col_parity ^ test_ecc->col_parity; |
| delta_line = read_ecc->line_parity ^ test_ecc->line_parity; |
| delta_line_prime = |
| read_ecc->line_parity_prime ^ test_ecc->line_parity_prime; |
| |
| if ((delta_col | delta_line | delta_line_prime) == 0) |
| return 0; /* no error */ |
| |
| if (delta_line == ~delta_line_prime && |
| (((delta_col ^ (delta_col >> 1)) & 0x15) == 0x15)) { |
| /* Single bit (recoverable) error in data */ |
| |
| bit = 0; |
| |
| if (delta_col & 0x20) |
| bit |= 0x04; |
| if (delta_col & 0x08) |
| bit |= 0x02; |
| if (delta_col & 0x02) |
| bit |= 0x01; |
| |
| if (delta_line >= n_bytes) |
| return -1; |
| |
| data[delta_line] ^= (1 << bit); |
| |
| return 1; /* corrected */ |
| } |
| |
| if ((hweight32(delta_line) + |
| hweight32(delta_line_prime) + |
| hweight8(delta_col)) == 1) { |
| /* Reccoverable error in ecc */ |
| |
| *read_ecc = *test_ecc; |
| return 1; /* corrected */ |
| } |
| |
| /* Unrecoverable error */ |
| |
| return -1; |
| } |