1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * This file contains an ECC algorithm that detects and corrects 1 bit
4 * errors in a 256 byte block of data.
5 *
6 * Copyright © 2008 Koninklijke Philips Electronics NV.
7 * Author: Frans Meulenbroeks
8 *
9 * Completely replaces the previous ECC implementation which was written by:
10 * Steven J. Hill (sjhill@realitydiluted.com)
11 * Thomas Gleixner (tglx@linutronix.de)
12 *
13 * Information on how this algorithm works and how it was developed
14 * can be found in Documentation/driver-api/mtd/nand_ecc.rst
15 */
16
17#include <linux/types.h>
18#include <linux/kernel.h>
19#include <linux/module.h>
20#include <linux/mtd/nand.h>
21#include <linux/mtd/nand-ecc-sw-hamming.h>
22#include <linux/slab.h>
23#include <asm/byteorder.h>
24
25/*
26 * invparity is a 256 byte table that contains the odd parity
27 * for each byte. So if the number of bits in a byte is even,
28 * the array element is 1, and when the number of bits is odd
29 * the array eleemnt is 0.
30 */
31static const char invparity[256] = {
32 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
33 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
34 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
35 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
36 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
37 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
38 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
39 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
40 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
41 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
42 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
43 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
44 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
45 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
46 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
47 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
48};
49
50/*
51 * bitsperbyte contains the number of bits per byte
52 * this is only used for testing and repairing parity
53 * (a precalculated value slightly improves performance)
54 */
55static const char bitsperbyte[256] = {
56 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
57 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
58 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
59 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
60 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
61 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
62 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
63 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
64 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
65 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
66 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
67 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
68 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
69 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
70 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
71 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
72};
73
74/*
75 * addressbits is a lookup table to filter out the bits from the xor-ed
76 * ECC data that identify the faulty location.
77 * this is only used for repairing parity
78 * see the comments in nand_ecc_sw_hamming_correct for more details
79 */
80static const char addressbits[256] = {
81 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
82 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
83 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
84 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
85 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
86 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
87 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
88 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
89 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
90 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
91 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
92 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
93 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
94 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
95 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
96 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
97 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
98 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
99 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
100 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
101 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
102 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
103 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
104 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
105 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
106 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
107 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
108 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
109 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
110 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
111 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
112 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f
113};
114
115int ecc_sw_hamming_calculate(const unsigned char *buf, unsigned int step_size,
116 unsigned char *code, bool sm_order)
117{
118 const u32 *bp = (uint32_t *)buf;
119 const u32 eccsize_mult = (step_size == 256) ? 1 : 2;
120 /* current value in buffer */
121 u32 cur;
122 /* rp0..rp17 are the various accumulated parities (per byte) */
123 u32 rp0, rp1, rp2, rp3, rp4, rp5, rp6, rp7, rp8, rp9, rp10, rp11, rp12,
124 rp13, rp14, rp15, rp16, rp17;
125 /* Cumulative parity for all data */
126 u32 par;
127 /* Cumulative parity at the end of the loop (rp12, rp14, rp16) */
128 u32 tmppar;
129 int i;
130
131 par = 0;
132 rp4 = 0;
133 rp6 = 0;
134 rp8 = 0;
135 rp10 = 0;
136 rp12 = 0;
137 rp14 = 0;
138 rp16 = 0;
139 rp17 = 0;
140
141 /*
142 * The loop is unrolled a number of times;
143 * This avoids if statements to decide on which rp value to update
144 * Also we process the data by longwords.
145 * Note: passing unaligned data might give a performance penalty.
146 * It is assumed that the buffers are aligned.
147 * tmppar is the cumulative sum of this iteration.
148 * needed for calculating rp12, rp14, rp16 and par
149 * also used as a performance improvement for rp6, rp8 and rp10
150 */
151 for (i = 0; i < eccsize_mult << 2; i++) {
152 cur = *bp++;
153 tmppar = cur;
154 rp4 ^= cur;
155 cur = *bp++;
156 tmppar ^= cur;
157 rp6 ^= tmppar;
158 cur = *bp++;
159 tmppar ^= cur;
160 rp4 ^= cur;
161 cur = *bp++;
162 tmppar ^= cur;
163 rp8 ^= tmppar;
164
165 cur = *bp++;
166 tmppar ^= cur;
167 rp4 ^= cur;
168 rp6 ^= cur;
169 cur = *bp++;
170 tmppar ^= cur;
171 rp6 ^= cur;
172 cur = *bp++;
173 tmppar ^= cur;
174 rp4 ^= cur;
175 cur = *bp++;
176 tmppar ^= cur;
177 rp10 ^= tmppar;
178
179 cur = *bp++;
180 tmppar ^= cur;
181 rp4 ^= cur;
182 rp6 ^= cur;
183 rp8 ^= cur;
184 cur = *bp++;
185 tmppar ^= cur;
186 rp6 ^= cur;
187 rp8 ^= cur;
188 cur = *bp++;
189 tmppar ^= cur;
190 rp4 ^= cur;
191 rp8 ^= cur;
192 cur = *bp++;
193 tmppar ^= cur;
194 rp8 ^= cur;
195
196 cur = *bp++;
197 tmppar ^= cur;
198 rp4 ^= cur;
199 rp6 ^= cur;
200 cur = *bp++;
201 tmppar ^= cur;
202 rp6 ^= cur;
203 cur = *bp++;
204 tmppar ^= cur;
205 rp4 ^= cur;
206 cur = *bp++;
207 tmppar ^= cur;
208
209 par ^= tmppar;
210 if ((i & 0x1) == 0)
211 rp12 ^= tmppar;
212 if ((i & 0x2) == 0)
213 rp14 ^= tmppar;
214 if (eccsize_mult == 2 && (i & 0x4) == 0)
215 rp16 ^= tmppar;
216 }
217
218 /*
219 * handle the fact that we use longword operations
220 * we'll bring rp4..rp14..rp16 back to single byte entities by
221 * shifting and xoring first fold the upper and lower 16 bits,
222 * then the upper and lower 8 bits.
223 */
224 rp4 ^= (rp4 >> 16);
225 rp4 ^= (rp4 >> 8);
226 rp4 &= 0xff;
227 rp6 ^= (rp6 >> 16);
228 rp6 ^= (rp6 >> 8);
229 rp6 &= 0xff;
230 rp8 ^= (rp8 >> 16);
231 rp8 ^= (rp8 >> 8);
232 rp8 &= 0xff;
233 rp10 ^= (rp10 >> 16);
234 rp10 ^= (rp10 >> 8);
235 rp10 &= 0xff;
236 rp12 ^= (rp12 >> 16);
237 rp12 ^= (rp12 >> 8);
238 rp12 &= 0xff;
239 rp14 ^= (rp14 >> 16);
240 rp14 ^= (rp14 >> 8);
241 rp14 &= 0xff;
242 if (eccsize_mult == 2) {
243 rp16 ^= (rp16 >> 16);
244 rp16 ^= (rp16 >> 8);
245 rp16 &= 0xff;
246 }
247
248 /*
249 * we also need to calculate the row parity for rp0..rp3
250 * This is present in par, because par is now
251 * rp3 rp3 rp2 rp2 in little endian and
252 * rp2 rp2 rp3 rp3 in big endian
253 * as well as
254 * rp1 rp0 rp1 rp0 in little endian and
255 * rp0 rp1 rp0 rp1 in big endian
256 * First calculate rp2 and rp3
257 */
258#ifdef __BIG_ENDIAN
259 rp2 = (par >> 16);
260 rp2 ^= (rp2 >> 8);
261 rp2 &= 0xff;
262 rp3 = par & 0xffff;
263 rp3 ^= (rp3 >> 8);
264 rp3 &= 0xff;
265#else
266 rp3 = (par >> 16);
267 rp3 ^= (rp3 >> 8);
268 rp3 &= 0xff;
269 rp2 = par & 0xffff;
270 rp2 ^= (rp2 >> 8);
271 rp2 &= 0xff;
272#endif
273
274 /* reduce par to 16 bits then calculate rp1 and rp0 */
275 par ^= (par >> 16);
276#ifdef __BIG_ENDIAN
277 rp0 = (par >> 8) & 0xff;
278 rp1 = (par & 0xff);
279#else
280 rp1 = (par >> 8) & 0xff;
281 rp0 = (par & 0xff);
282#endif
283
284 /* finally reduce par to 8 bits */
285 par ^= (par >> 8);
286 par &= 0xff;
287
288 /*
289 * and calculate rp5..rp15..rp17
290 * note that par = rp4 ^ rp5 and due to the commutative property
291 * of the ^ operator we can say:
292 * rp5 = (par ^ rp4);
293 * The & 0xff seems superfluous, but benchmarking learned that
294 * leaving it out gives slightly worse results. No idea why, probably
295 * it has to do with the way the pipeline in pentium is organized.
296 */
297 rp5 = (par ^ rp4) & 0xff;
298 rp7 = (par ^ rp6) & 0xff;
299 rp9 = (par ^ rp8) & 0xff;
300 rp11 = (par ^ rp10) & 0xff;
301 rp13 = (par ^ rp12) & 0xff;
302 rp15 = (par ^ rp14) & 0xff;
303 if (eccsize_mult == 2)
304 rp17 = (par ^ rp16) & 0xff;
305
306 /*
307 * Finally calculate the ECC bits.
308 * Again here it might seem that there are performance optimisations
309 * possible, but benchmarks showed that on the system this is developed
310 * the code below is the fastest
311 */
312 if (sm_order) {
313 code[0] = (invparity[rp7] << 7) | (invparity[rp6] << 6) |
314 (invparity[rp5] << 5) | (invparity[rp4] << 4) |
315 (invparity[rp3] << 3) | (invparity[rp2] << 2) |
316 (invparity[rp1] << 1) | (invparity[rp0]);
317 code[1] = (invparity[rp15] << 7) | (invparity[rp14] << 6) |
318 (invparity[rp13] << 5) | (invparity[rp12] << 4) |
319 (invparity[rp11] << 3) | (invparity[rp10] << 2) |
320 (invparity[rp9] << 1) | (invparity[rp8]);
321 } else {
322 code[1] = (invparity[rp7] << 7) | (invparity[rp6] << 6) |
323 (invparity[rp5] << 5) | (invparity[rp4] << 4) |
324 (invparity[rp3] << 3) | (invparity[rp2] << 2) |
325 (invparity[rp1] << 1) | (invparity[rp0]);
326 code[0] = (invparity[rp15] << 7) | (invparity[rp14] << 6) |
327 (invparity[rp13] << 5) | (invparity[rp12] << 4) |
328 (invparity[rp11] << 3) | (invparity[rp10] << 2) |
329 (invparity[rp9] << 1) | (invparity[rp8]);
330 }
331
332 if (eccsize_mult == 1)
333 code[2] =
334 (invparity[par & 0xf0] << 7) |
335 (invparity[par & 0x0f] << 6) |
336 (invparity[par & 0xcc] << 5) |
337 (invparity[par & 0x33] << 4) |
338 (invparity[par & 0xaa] << 3) |
339 (invparity[par & 0x55] << 2) |
340 3;
341 else
342 code[2] =
343 (invparity[par & 0xf0] << 7) |
344 (invparity[par & 0x0f] << 6) |
345 (invparity[par & 0xcc] << 5) |
346 (invparity[par & 0x33] << 4) |
347 (invparity[par & 0xaa] << 3) |
348 (invparity[par & 0x55] << 2) |
349 (invparity[rp17] << 1) |
350 (invparity[rp16] << 0);
351
352 return 0;
353}
354EXPORT_SYMBOL(ecc_sw_hamming_calculate);
355
356/**
357 * nand_ecc_sw_hamming_calculate - Calculate 3-byte ECC for 256/512-byte block
358 * @nand: NAND device
359 * @buf: Input buffer with raw data
360 * @code: Output buffer with ECC
361 */
362int nand_ecc_sw_hamming_calculate(struct nand_device *nand,
363 const unsigned char *buf, unsigned char *code)
364{
365 struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
366 unsigned int step_size = nand->ecc.ctx.conf.step_size;
367 bool sm_order = engine_conf ? engine_conf->sm_order : false;
368
369 return ecc_sw_hamming_calculate(buf, step_size, code, sm_order);
370}
371EXPORT_SYMBOL(nand_ecc_sw_hamming_calculate);
372
373int ecc_sw_hamming_correct(unsigned char *buf, unsigned char *read_ecc,
374 unsigned char *calc_ecc, unsigned int step_size,
375 bool sm_order)
376{
377 const u32 eccsize_mult = step_size >> 8;
378 unsigned char b0, b1, b2, bit_addr;
379 unsigned int byte_addr;
380
381 /*
382 * b0 to b2 indicate which bit is faulty (if any)
383 * we might need the xor result more than once,
384 * so keep them in a local var
385 */
386 if (sm_order) {
387 b0 = read_ecc[0] ^ calc_ecc[0];
388 b1 = read_ecc[1] ^ calc_ecc[1];
389 } else {
390 b0 = read_ecc[1] ^ calc_ecc[1];
391 b1 = read_ecc[0] ^ calc_ecc[0];
392 }
393
394 b2 = read_ecc[2] ^ calc_ecc[2];
395
396 /* check if there are any bitfaults */
397
398 /* repeated if statements are slightly more efficient than switch ... */
399 /* ordered in order of likelihood */
400
401 if ((b0 | b1 | b2) == 0)
402 return 0; /* no error */
403
404 if ((((b0 ^ (b0 >> 1)) & 0x55) == 0x55) &&
405 (((b1 ^ (b1 >> 1)) & 0x55) == 0x55) &&
406 ((eccsize_mult == 1 && ((b2 ^ (b2 >> 1)) & 0x54) == 0x54) ||
407 (eccsize_mult == 2 && ((b2 ^ (b2 >> 1)) & 0x55) == 0x55))) {
408 /* single bit error */
409 /*
410 * rp17/rp15/13/11/9/7/5/3/1 indicate which byte is the faulty
411 * byte, cp 5/3/1 indicate the faulty bit.
412 * A lookup table (called addressbits) is used to filter
413 * the bits from the byte they are in.
414 * A marginal optimisation is possible by having three
415 * different lookup tables.
416 * One as we have now (for b0), one for b2
417 * (that would avoid the >> 1), and one for b1 (with all values
418 * << 4). However it was felt that introducing two more tables
419 * hardly justify the gain.
420 *
421 * The b2 shift is there to get rid of the lowest two bits.
422 * We could also do addressbits[b2] >> 1 but for the
423 * performance it does not make any difference
424 */
425 if (eccsize_mult == 1)
426 byte_addr = (addressbits[b1] << 4) + addressbits[b0];
427 else
428 byte_addr = (addressbits[b2 & 0x3] << 8) +
429 (addressbits[b1] << 4) + addressbits[b0];
430 bit_addr = addressbits[b2 >> 2];
431 /* flip the bit */
432 buf[byte_addr] ^= (1 << bit_addr);
433 return 1;
434
435 }
436 /* count nr of bits; use table lookup, faster than calculating it */
437 if ((bitsperbyte[b0] + bitsperbyte[b1] + bitsperbyte[b2]) == 1)
438 return 1; /* error in ECC data; no action needed */
439
440 pr_err("%s: uncorrectable ECC error\n", __func__);
441 return -EBADMSG;
442}
443EXPORT_SYMBOL(ecc_sw_hamming_correct);
444
445/**
446 * nand_ecc_sw_hamming_correct - Detect and correct bit error(s)
447 * @nand: NAND device
448 * @buf: Raw data read from the chip
449 * @read_ecc: ECC bytes read from the chip
450 * @calc_ecc: ECC calculated from the raw data
451 *
452 * Detect and correct up to 1 bit error per 256/512-byte block.
453 */
454int nand_ecc_sw_hamming_correct(struct nand_device *nand, unsigned char *buf,
455 unsigned char *read_ecc,
456 unsigned char *calc_ecc)
457{
458 struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
459 unsigned int step_size = nand->ecc.ctx.conf.step_size;
460 bool sm_order = engine_conf ? engine_conf->sm_order : false;
461
462 return ecc_sw_hamming_correct(buf, read_ecc, calc_ecc, step_size,
463 sm_order);
464}
465EXPORT_SYMBOL(nand_ecc_sw_hamming_correct);
466
467int nand_ecc_sw_hamming_init_ctx(struct nand_device *nand)
468{
469 struct nand_ecc_props *conf = &nand->ecc.ctx.conf;
470 struct nand_ecc_sw_hamming_conf *engine_conf;
471 struct mtd_info *mtd = nanddev_to_mtd(nand);
472 int ret;
473
474 if (!mtd->ooblayout) {
475 switch (mtd->oobsize) {
476 case 8:
477 case 16:
478 mtd_set_ooblayout(mtd, ooblayout: nand_get_small_page_ooblayout());
479 break;
480 case 64:
481 case 128:
482 mtd_set_ooblayout(mtd,
483 ooblayout: nand_get_large_page_hamming_ooblayout());
484 break;
485 default:
486 return -ENOTSUPP;
487 }
488 }
489
490 conf->engine_type = NAND_ECC_ENGINE_TYPE_SOFT;
491 conf->algo = NAND_ECC_ALGO_HAMMING;
492 conf->step_size = nand->ecc.user_conf.step_size;
493 conf->strength = 1;
494
495 /* Use the strongest configuration by default */
496 if (conf->step_size != 256 && conf->step_size != 512)
497 conf->step_size = 256;
498
499 engine_conf = kzalloc(size: sizeof(*engine_conf), GFP_KERNEL);
500 if (!engine_conf)
501 return -ENOMEM;
502
503 ret = nand_ecc_init_req_tweaking(ctx: &engine_conf->req_ctx, nand);
504 if (ret)
505 goto free_engine_conf;
506
507 engine_conf->code_size = 3;
508 engine_conf->calc_buf = kzalloc(size: mtd->oobsize, GFP_KERNEL);
509 engine_conf->code_buf = kzalloc(size: mtd->oobsize, GFP_KERNEL);
510 if (!engine_conf->calc_buf || !engine_conf->code_buf) {
511 ret = -ENOMEM;
512 goto free_bufs;
513 }
514
515 nand->ecc.ctx.priv = engine_conf;
516 nand->ecc.ctx.nsteps = mtd->writesize / conf->step_size;
517 nand->ecc.ctx.total = nand->ecc.ctx.nsteps * engine_conf->code_size;
518
519 return 0;
520
521free_bufs:
522 nand_ecc_cleanup_req_tweaking(ctx: &engine_conf->req_ctx);
523 kfree(objp: engine_conf->calc_buf);
524 kfree(objp: engine_conf->code_buf);
525free_engine_conf:
526 kfree(objp: engine_conf);
527
528 return ret;
529}
530EXPORT_SYMBOL(nand_ecc_sw_hamming_init_ctx);
531
532void nand_ecc_sw_hamming_cleanup_ctx(struct nand_device *nand)
533{
534 struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
535
536 if (engine_conf) {
537 nand_ecc_cleanup_req_tweaking(ctx: &engine_conf->req_ctx);
538 kfree(objp: engine_conf->calc_buf);
539 kfree(objp: engine_conf->code_buf);
540 kfree(objp: engine_conf);
541 }
542}
543EXPORT_SYMBOL(nand_ecc_sw_hamming_cleanup_ctx);
544
545static int nand_ecc_sw_hamming_prepare_io_req(struct nand_device *nand,
546 struct nand_page_io_req *req)
547{
548 struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
549 struct mtd_info *mtd = nanddev_to_mtd(nand);
550 int eccsize = nand->ecc.ctx.conf.step_size;
551 int eccbytes = engine_conf->code_size;
552 int eccsteps = nand->ecc.ctx.nsteps;
553 int total = nand->ecc.ctx.total;
554 u8 *ecccalc = engine_conf->calc_buf;
555 const u8 *data;
556 int i;
557
558 /* Nothing to do for a raw operation */
559 if (req->mode == MTD_OPS_RAW)
560 return 0;
561
562 /* This engine does not provide BBM/free OOB bytes protection */
563 if (!req->datalen)
564 return 0;
565
566 nand_ecc_tweak_req(ctx: &engine_conf->req_ctx, req);
567
568 /* No more preparation for page read */
569 if (req->type == NAND_PAGE_READ)
570 return 0;
571
572 /* Preparation for page write: derive the ECC bytes and place them */
573 for (i = 0, data = req->databuf.out;
574 eccsteps;
575 eccsteps--, i += eccbytes, data += eccsize)
576 nand_ecc_sw_hamming_calculate(nand, data, &ecccalc[i]);
577
578 return mtd_ooblayout_set_eccbytes(mtd, eccbuf: ecccalc, oobbuf: (void *)req->oobbuf.out,
579 start: 0, nbytes: total);
580}
581
582static int nand_ecc_sw_hamming_finish_io_req(struct nand_device *nand,
583 struct nand_page_io_req *req)
584{
585 struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
586 struct mtd_info *mtd = nanddev_to_mtd(nand);
587 int eccsize = nand->ecc.ctx.conf.step_size;
588 int total = nand->ecc.ctx.total;
589 int eccbytes = engine_conf->code_size;
590 int eccsteps = nand->ecc.ctx.nsteps;
591 u8 *ecccalc = engine_conf->calc_buf;
592 u8 *ecccode = engine_conf->code_buf;
593 unsigned int max_bitflips = 0;
594 u8 *data = req->databuf.in;
595 int i, ret;
596
597 /* Nothing to do for a raw operation */
598 if (req->mode == MTD_OPS_RAW)
599 return 0;
600
601 /* This engine does not provide BBM/free OOB bytes protection */
602 if (!req->datalen)
603 return 0;
604
605 /* No more preparation for page write */
606 if (req->type == NAND_PAGE_WRITE) {
607 nand_ecc_restore_req(ctx: &engine_conf->req_ctx, req);
608 return 0;
609 }
610
611 /* Finish a page read: retrieve the (raw) ECC bytes*/
612 ret = mtd_ooblayout_get_eccbytes(mtd, eccbuf: ecccode, oobbuf: req->oobbuf.in, start: 0,
613 nbytes: total);
614 if (ret)
615 return ret;
616
617 /* Calculate the ECC bytes */
618 for (i = 0; eccsteps; eccsteps--, i += eccbytes, data += eccsize)
619 nand_ecc_sw_hamming_calculate(nand, data, &ecccalc[i]);
620
621 /* Finish a page read: compare and correct */
622 for (eccsteps = nand->ecc.ctx.nsteps, i = 0, data = req->databuf.in;
623 eccsteps;
624 eccsteps--, i += eccbytes, data += eccsize) {
625 int stat = nand_ecc_sw_hamming_correct(nand, data,
626 &ecccode[i],
627 &ecccalc[i]);
628 if (stat < 0) {
629 mtd->ecc_stats.failed++;
630 } else {
631 mtd->ecc_stats.corrected += stat;
632 max_bitflips = max_t(unsigned int, max_bitflips, stat);
633 }
634 }
635
636 nand_ecc_restore_req(ctx: &engine_conf->req_ctx, req);
637
638 return max_bitflips;
639}
640
641static struct nand_ecc_engine_ops nand_ecc_sw_hamming_engine_ops = {
642 .init_ctx = nand_ecc_sw_hamming_init_ctx,
643 .cleanup_ctx = nand_ecc_sw_hamming_cleanup_ctx,
644 .prepare_io_req = nand_ecc_sw_hamming_prepare_io_req,
645 .finish_io_req = nand_ecc_sw_hamming_finish_io_req,
646};
647
648static struct nand_ecc_engine nand_ecc_sw_hamming_engine = {
649 .ops = &nand_ecc_sw_hamming_engine_ops,
650};
651
652struct nand_ecc_engine *nand_ecc_sw_hamming_get_engine(void)
653{
654 return &nand_ecc_sw_hamming_engine;
655}
656EXPORT_SYMBOL(nand_ecc_sw_hamming_get_engine);
657
658MODULE_LICENSE("GPL");
659MODULE_AUTHOR("Frans Meulenbroeks <fransmeulenbroeks@gmail.com>");
660MODULE_DESCRIPTION("NAND software Hamming ECC support");
661

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source code of linux/drivers/mtd/nand/ecc-sw-hamming.c