1 /*
2  * sharpslpart.c - MTD partition parser for NAND flash using the SHARP FTL
3  * for logical addressing, as used on the PXA models of the SHARP SL Series.
4  *
5  * Copyright (C) 2017 Andrea Adami <andrea.adami@gmail.com>
6  *
7  * Based on SHARP GPL 2.4 sources:
8  *   http://support.ezaurus.com/developer/source/source_dl.asp
9  *     drivers/mtd/nand/sharp_sl_logical.c
10  *     linux/include/asm-arm/sharp_nand_logical.h
11  *
12  * Copyright (C) 2002 SHARP
13  *
14  * This program is free software; you can redistribute it and/or modify
15  * it under the terms of the GNU General Public License as published by
16  * the Free Software Foundation; either version 2 of the License, or
17  * (at your option) any later version.
18  *
19  * This program is distributed in the hope that it will be useful,
20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22  * GNU General Public License for more details.
23  *
24  */
25 
26 #include <linux/kernel.h>
27 #include <linux/slab.h>
28 #include <linux/module.h>
29 #include <linux/types.h>
30 #include <linux/bitops.h>
31 #include <linux/sizes.h>
32 #include <linux/mtd/mtd.h>
33 #include <linux/mtd/partitions.h>
34 
35 /* oob structure */
36 #define NAND_NOOB_LOGADDR_00		8
37 #define NAND_NOOB_LOGADDR_01		9
38 #define NAND_NOOB_LOGADDR_10		10
39 #define NAND_NOOB_LOGADDR_11		11
40 #define NAND_NOOB_LOGADDR_20		12
41 #define NAND_NOOB_LOGADDR_21		13
42 
43 #define BLOCK_IS_RESERVED		0xffff
44 #define BLOCK_UNMASK_COMPLEMENT		1
45 
46 /* factory defaults */
47 #define SHARPSL_NAND_PARTS		3
48 #define SHARPSL_FTL_PART_SIZE		(7 * SZ_1M)
49 #define SHARPSL_PARTINFO1_LADDR		0x00060000
50 #define SHARPSL_PARTINFO2_LADDR		0x00064000
51 
52 #define BOOT_MAGIC			0x424f4f54
53 #define FSRO_MAGIC			0x4653524f
54 #define FSRW_MAGIC			0x46535257
55 
56 /**
57  * struct sharpsl_ftl - Sharp FTL Logical Table
58  * @logmax:		number of logical blocks
59  * @log2phy:		the logical-to-physical table
60  *
61  * Structure containing the logical-to-physical translation table
62  * used by the SHARP SL FTL.
63  */
64 struct sharpsl_ftl {
65 	unsigned int logmax;
66 	unsigned int *log2phy;
67 };
68 
69 /* verify that the OOB bytes 8 to 15 are free and available for the FTL */
70 static int sharpsl_nand_check_ooblayout(struct mtd_info *mtd)
71 {
72 	u8 freebytes = 0;
73 	int section = 0;
74 
75 	while (true) {
76 		struct mtd_oob_region oobfree = { };
77 		int ret, i;
78 
79 		ret = mtd_ooblayout_free(mtd, section++, &oobfree);
80 		if (ret)
81 			break;
82 
83 		if (!oobfree.length || oobfree.offset > 15 ||
84 		    (oobfree.offset + oobfree.length) < 8)
85 			continue;
86 
87 		i = oobfree.offset >= 8 ? oobfree.offset : 8;
88 		for (; i < oobfree.offset + oobfree.length && i < 16; i++)
89 			freebytes |= BIT(i - 8);
90 
91 		if (freebytes == 0xff)
92 			return 0;
93 	}
94 
95 	return -ENOTSUPP;
96 }
97 
98 static int sharpsl_nand_read_oob(struct mtd_info *mtd, loff_t offs, u8 *buf)
99 {
100 	struct mtd_oob_ops ops = { };
101 	int ret;
102 
103 	ops.mode = MTD_OPS_PLACE_OOB;
104 	ops.ooblen = mtd->oobsize;
105 	ops.oobbuf = buf;
106 
107 	ret = mtd_read_oob(mtd, offs, &ops);
108 	if (ret != 0 || mtd->oobsize != ops.oobretlen)
109 		return -1;
110 
111 	return 0;
112 }
113 
114 /*
115  * The logical block number assigned to a physical block is stored in the OOB
116  * of the first page, in 3 16-bit copies with the following layout:
117  *
118  * 01234567 89abcdef
119  * -------- --------
120  * ECC BB   xyxyxy
121  *
122  * When reading we check that the first two copies agree.
123  * In case of error, matching is tried using the following pairs.
124  * Reserved values 0xffff mean the block is kept for wear leveling.
125  *
126  * 01234567 89abcdef
127  * -------- --------
128  * ECC BB   xyxy    oob[8]==oob[10] && oob[9]==oob[11]   -> byte0=8   byte1=9
129  * ECC BB     xyxy  oob[10]==oob[12] && oob[11]==oob[13] -> byte0=10  byte1=11
130  * ECC BB   xy  xy  oob[12]==oob[8] && oob[13]==oob[9]   -> byte0=12  byte1=13
131  */
132 static int sharpsl_nand_get_logical_num(u8 *oob)
133 {
134 	u16 us;
135 	int good0, good1;
136 
137 	if (oob[NAND_NOOB_LOGADDR_00] == oob[NAND_NOOB_LOGADDR_10] &&
138 	    oob[NAND_NOOB_LOGADDR_01] == oob[NAND_NOOB_LOGADDR_11]) {
139 		good0 = NAND_NOOB_LOGADDR_00;
140 		good1 = NAND_NOOB_LOGADDR_01;
141 	} else if (oob[NAND_NOOB_LOGADDR_10] == oob[NAND_NOOB_LOGADDR_20] &&
142 		   oob[NAND_NOOB_LOGADDR_11] == oob[NAND_NOOB_LOGADDR_21]) {
143 		good0 = NAND_NOOB_LOGADDR_10;
144 		good1 = NAND_NOOB_LOGADDR_11;
145 	} else if (oob[NAND_NOOB_LOGADDR_20] == oob[NAND_NOOB_LOGADDR_00] &&
146 		   oob[NAND_NOOB_LOGADDR_21] == oob[NAND_NOOB_LOGADDR_01]) {
147 		good0 = NAND_NOOB_LOGADDR_20;
148 		good1 = NAND_NOOB_LOGADDR_21;
149 	} else {
150 		return -EINVAL;
151 	}
152 
153 	us = oob[good0] | oob[good1] << 8;
154 
155 	/* parity check */
156 	if (hweight16(us) & BLOCK_UNMASK_COMPLEMENT)
157 		return -EINVAL;
158 
159 	/* reserved */
160 	if (us == BLOCK_IS_RESERVED)
161 		return BLOCK_IS_RESERVED;
162 
163 	return (us >> 1) & GENMASK(9, 0);
164 }
165 
166 static int sharpsl_nand_init_ftl(struct mtd_info *mtd, struct sharpsl_ftl *ftl)
167 {
168 	unsigned int block_num, log_num, phymax;
169 	loff_t block_adr;
170 	u8 *oob;
171 	int i, ret;
172 
173 	oob = kzalloc(mtd->oobsize, GFP_KERNEL);
174 	if (!oob)
175 		return -ENOMEM;
176 
177 	phymax = mtd_div_by_eb(SHARPSL_FTL_PART_SIZE, mtd);
178 
179 	/* FTL reserves 5% of the blocks + 1 spare  */
180 	ftl->logmax = ((phymax * 95) / 100) - 1;
181 
182 	ftl->log2phy = kmalloc_array(ftl->logmax, sizeof(*ftl->log2phy),
183 				     GFP_KERNEL);
184 	if (!ftl->log2phy) {
185 		ret = -ENOMEM;
186 		goto exit;
187 	}
188 
189 	/* initialize ftl->log2phy */
190 	for (i = 0; i < ftl->logmax; i++)
191 		ftl->log2phy[i] = UINT_MAX;
192 
193 	/* create physical-logical table */
194 	for (block_num = 0; block_num < phymax; block_num++) {
195 		block_adr = (loff_t)block_num * mtd->erasesize;
196 
197 		if (mtd_block_isbad(mtd, block_adr))
198 			continue;
199 
200 		if (sharpsl_nand_read_oob(mtd, block_adr, oob))
201 			continue;
202 
203 		/* get logical block */
204 		log_num = sharpsl_nand_get_logical_num(oob);
205 
206 		/* cut-off errors and skip the out-of-range values */
207 		if (log_num > 0 && log_num < ftl->logmax) {
208 			if (ftl->log2phy[log_num] == UINT_MAX)
209 				ftl->log2phy[log_num] = block_num;
210 		}
211 	}
212 
213 	pr_info("Sharp SL FTL: %d blocks used (%d logical, %d reserved)\n",
214 		phymax, ftl->logmax, phymax - ftl->logmax);
215 
216 	ret = 0;
217 exit:
218 	kfree(oob);
219 	return ret;
220 }
221 
222 static void sharpsl_nand_cleanup_ftl(struct sharpsl_ftl *ftl)
223 {
224 	kfree(ftl->log2phy);
225 }
226 
227 static int sharpsl_nand_read_laddr(struct mtd_info *mtd,
228 				   loff_t from,
229 				   size_t len,
230 				   void *buf,
231 				   struct sharpsl_ftl *ftl)
232 {
233 	unsigned int log_num, final_log_num;
234 	unsigned int block_num;
235 	loff_t block_adr;
236 	loff_t block_ofs;
237 	size_t retlen;
238 	int err;
239 
240 	log_num = mtd_div_by_eb((u32)from, mtd);
241 	final_log_num = mtd_div_by_eb(((u32)from + len - 1), mtd);
242 
243 	if (len <= 0 || log_num >= ftl->logmax || final_log_num > log_num)
244 		return -EINVAL;
245 
246 	block_num = ftl->log2phy[log_num];
247 	block_adr = (loff_t)block_num * mtd->erasesize;
248 	block_ofs = mtd_mod_by_eb((u32)from, mtd);
249 
250 	err = mtd_read(mtd, block_adr + block_ofs, len, &retlen, buf);
251 	/* Ignore corrected ECC errors */
252 	if (mtd_is_bitflip(err))
253 		err = 0;
254 
255 	if (!err && retlen != len)
256 		err = -EIO;
257 
258 	if (err)
259 		pr_err("sharpslpart: error, read failed at %#llx\n",
260 		       block_adr + block_ofs);
261 
262 	return err;
263 }
264 
265 /*
266  * MTD Partition Parser
267  *
268  * Sample values read from SL-C860
269  *
270  * # cat /proc/mtd
271  * dev:    size   erasesize  name
272  * mtd0: 006d0000 00020000 "Filesystem"
273  * mtd1: 00700000 00004000 "smf"
274  * mtd2: 03500000 00004000 "root"
275  * mtd3: 04400000 00004000 "home"
276  *
277  * PARTITIONINFO1
278  * 0x00060000: 00 00 00 00 00 00 70 00 42 4f 4f 54 00 00 00 00  ......p.BOOT....
279  * 0x00060010: 00 00 70 00 00 00 c0 03 46 53 52 4f 00 00 00 00  ..p.....FSRO....
280  * 0x00060020: 00 00 c0 03 00 00 00 04 46 53 52 57 00 00 00 00  ........FSRW....
281  */
282 struct sharpsl_nand_partinfo {
283 	__le32 start;
284 	__le32 end;
285 	__be32 magic;
286 	u32 reserved;
287 };
288 
289 static int sharpsl_nand_read_partinfo(struct mtd_info *master,
290 				      loff_t from,
291 				      size_t len,
292 				      struct sharpsl_nand_partinfo *buf,
293 				      struct sharpsl_ftl *ftl)
294 {
295 	int ret;
296 
297 	ret = sharpsl_nand_read_laddr(master, from, len, buf, ftl);
298 	if (ret)
299 		return ret;
300 
301 	/* check for magics */
302 	if (be32_to_cpu(buf[0].magic) != BOOT_MAGIC ||
303 	    be32_to_cpu(buf[1].magic) != FSRO_MAGIC ||
304 	    be32_to_cpu(buf[2].magic) != FSRW_MAGIC) {
305 		pr_err("sharpslpart: magic values mismatch\n");
306 		return -EINVAL;
307 	}
308 
309 	/* fixup for hardcoded value 64 MiB (for older models) */
310 	buf[2].end = cpu_to_le32(master->size);
311 
312 	/* extra sanity check */
313 	if (le32_to_cpu(buf[0].end) <= le32_to_cpu(buf[0].start) ||
314 	    le32_to_cpu(buf[1].start) < le32_to_cpu(buf[0].end) ||
315 	    le32_to_cpu(buf[1].end) <= le32_to_cpu(buf[1].start) ||
316 	    le32_to_cpu(buf[2].start) < le32_to_cpu(buf[1].end) ||
317 	    le32_to_cpu(buf[2].end) <= le32_to_cpu(buf[2].start)) {
318 		pr_err("sharpslpart: partition sizes mismatch\n");
319 		return -EINVAL;
320 	}
321 
322 	return 0;
323 }
324 
325 static int sharpsl_parse_mtd_partitions(struct mtd_info *master,
326 					const struct mtd_partition **pparts,
327 					struct mtd_part_parser_data *data)
328 {
329 	struct sharpsl_ftl ftl;
330 	struct sharpsl_nand_partinfo buf[SHARPSL_NAND_PARTS];
331 	struct mtd_partition *sharpsl_nand_parts;
332 	int err;
333 
334 	/* check that OOB bytes 8 to 15 used by the FTL are actually free */
335 	err = sharpsl_nand_check_ooblayout(master);
336 	if (err)
337 		return err;
338 
339 	/* init logical mgmt (FTL) */
340 	err = sharpsl_nand_init_ftl(master, &ftl);
341 	if (err)
342 		return err;
343 
344 	/* read and validate first partition table */
345 	pr_info("sharpslpart: try reading first partition table\n");
346 	err = sharpsl_nand_read_partinfo(master,
347 					 SHARPSL_PARTINFO1_LADDR,
348 					 sizeof(buf), buf, &ftl);
349 	if (err) {
350 		/* fallback: read second partition table */
351 		pr_warn("sharpslpart: first partition table is invalid, retry using the second\n");
352 		err = sharpsl_nand_read_partinfo(master,
353 						 SHARPSL_PARTINFO2_LADDR,
354 						 sizeof(buf), buf, &ftl);
355 	}
356 
357 	/* cleanup logical mgmt (FTL) */
358 	sharpsl_nand_cleanup_ftl(&ftl);
359 
360 	if (err) {
361 		pr_err("sharpslpart: both partition tables are invalid\n");
362 		return err;
363 	}
364 
365 	sharpsl_nand_parts = kcalloc(SHARPSL_NAND_PARTS,
366 				     sizeof(*sharpsl_nand_parts),
367 				     GFP_KERNEL);
368 	if (!sharpsl_nand_parts)
369 		return -ENOMEM;
370 
371 	/* original names */
372 	sharpsl_nand_parts[0].name = "smf";
373 	sharpsl_nand_parts[0].offset = le32_to_cpu(buf[0].start);
374 	sharpsl_nand_parts[0].size = le32_to_cpu(buf[0].end) -
375 				     le32_to_cpu(buf[0].start);
376 
377 	sharpsl_nand_parts[1].name = "root";
378 	sharpsl_nand_parts[1].offset = le32_to_cpu(buf[1].start);
379 	sharpsl_nand_parts[1].size = le32_to_cpu(buf[1].end) -
380 				     le32_to_cpu(buf[1].start);
381 
382 	sharpsl_nand_parts[2].name = "home";
383 	sharpsl_nand_parts[2].offset = le32_to_cpu(buf[2].start);
384 	sharpsl_nand_parts[2].size = le32_to_cpu(buf[2].end) -
385 				     le32_to_cpu(buf[2].start);
386 
387 	*pparts = sharpsl_nand_parts;
388 	return SHARPSL_NAND_PARTS;
389 }
390 
391 static struct mtd_part_parser sharpsl_mtd_parser = {
392 	.parse_fn = sharpsl_parse_mtd_partitions,
393 	.name = "sharpslpart",
394 };
395 module_mtd_part_parser(sharpsl_mtd_parser);
396 
397 MODULE_LICENSE("GPL");
398 MODULE_AUTHOR("Andrea Adami <andrea.adami@gmail.com>");
399 MODULE_DESCRIPTION("MTD partitioning for NAND flash on Sharp SL Series");
400