1 /*
2 * BCM47XX MTD partitioning
3 *
4 * Copyright © 2012 Rafał Miłecki <zajec5@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 */
11
12 #include <linux/bcm47xx_nvram.h>
13 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/mtd/partitions.h>
18
19 #include <uapi/linux/magic.h>
20
21 /*
22 * NAND flash on Netgear R6250 was verified to contain 15 partitions.
23 * This will result in allocating too big array for some old devices, but the
24 * memory will be freed soon anyway (see mtd_device_parse_register).
25 */
26 #define BCM47XXPART_MAX_PARTS 20
27
28 /*
29 * Amount of bytes we read when analyzing each block of flash memory.
30 * Set it big enough to allow detecting partition and reading important data.
31 */
32 #define BCM47XXPART_BYTES_TO_READ 0x4e8
33
34 /* Magics */
35 #define BOARD_DATA_MAGIC 0x5246504D /* MPFR */
36 #define BOARD_DATA_MAGIC2 0xBD0D0BBD
37 #define CFE_MAGIC 0x43464531 /* 1EFC */
38 #define FACTORY_MAGIC 0x59544346 /* FCTY */
39 #define NVRAM_HEADER 0x48534C46 /* FLSH */
40 #define POT_MAGIC1 0x54544f50 /* POTT */
41 #define POT_MAGIC2 0x504f /* OP */
42 #define ML_MAGIC1 0x39685a42
43 #define ML_MAGIC2 0x26594131
44 #define TRX_MAGIC 0x30524448
45 #define SHSQ_MAGIC 0x71736873 /* shsq (weird ZTE H218N endianness) */
46
47 static const char * const trx_types[] = { "trx", NULL };
48
49 struct trx_header {
50 uint32_t magic;
51 uint32_t length;
52 uint32_t crc32;
53 uint16_t flags;
54 uint16_t version;
55 uint32_t offset[3];
56 } __packed;
57
bcm47xxpart_add_part(struct mtd_partition * part,const char * name,u64 offset,uint32_t mask_flags)58 static void bcm47xxpart_add_part(struct mtd_partition *part, const char *name,
59 u64 offset, uint32_t mask_flags)
60 {
61 part->name = name;
62 part->offset = offset;
63 part->mask_flags = mask_flags;
64 }
65
66 /**
67 * bcm47xxpart_bootpartition - gets index of TRX partition used by bootloader
68 *
69 * Some devices may have more than one TRX partition. In such case one of them
70 * is the main one and another a failsafe one. Bootloader may fallback to the
71 * failsafe firmware if it detects corruption of the main image.
72 *
73 * This function provides info about currently used TRX partition. It's the one
74 * containing kernel started by the bootloader.
75 */
bcm47xxpart_bootpartition(void)76 static int bcm47xxpart_bootpartition(void)
77 {
78 char buf[4];
79 int bootpartition;
80
81 /* Check CFE environment variable */
82 if (bcm47xx_nvram_getenv("bootpartition", buf, sizeof(buf)) > 0) {
83 if (!kstrtoint(buf, 0, &bootpartition))
84 return bootpartition;
85 }
86
87 return 0;
88 }
89
bcm47xxpart_parse(struct mtd_info * master,const struct mtd_partition ** pparts,struct mtd_part_parser_data * data)90 static int bcm47xxpart_parse(struct mtd_info *master,
91 const struct mtd_partition **pparts,
92 struct mtd_part_parser_data *data)
93 {
94 struct mtd_partition *parts;
95 uint8_t i, curr_part = 0;
96 uint32_t *buf;
97 size_t bytes_read;
98 uint32_t offset;
99 uint32_t blocksize = master->erasesize;
100 int trx_parts[2]; /* Array with indexes of TRX partitions */
101 int trx_num = 0; /* Number of found TRX partitions */
102 int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
103 int err;
104
105 /*
106 * Some really old flashes (like AT45DB*) had smaller erasesize-s, but
107 * partitions were aligned to at least 0x1000 anyway.
108 */
109 if (blocksize < 0x1000)
110 blocksize = 0x1000;
111
112 /* Alloc */
113 parts = kcalloc(BCM47XXPART_MAX_PARTS, sizeof(struct mtd_partition),
114 GFP_KERNEL);
115 if (!parts)
116 return -ENOMEM;
117
118 buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
119 if (!buf) {
120 kfree(parts);
121 return -ENOMEM;
122 }
123
124 /* Parse block by block looking for magics */
125 for (offset = 0; offset <= master->size - blocksize;
126 offset += blocksize) {
127 /* Nothing more in higher memory on BCM47XX (MIPS) */
128 if (IS_ENABLED(CONFIG_BCM47XX) && offset >= 0x2000000)
129 break;
130
131 if (curr_part >= BCM47XXPART_MAX_PARTS) {
132 pr_warn("Reached maximum number of partitions, scanning stopped!\n");
133 break;
134 }
135
136 /* Read beginning of the block */
137 err = mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
138 &bytes_read, (uint8_t *)buf);
139 if (err && !mtd_is_bitflip(err)) {
140 pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
141 offset, err);
142 continue;
143 }
144
145 /* Magic or small NVRAM at 0x400 */
146 if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
147 (buf[0x400 / 4] == NVRAM_HEADER)) {
148 bcm47xxpart_add_part(&parts[curr_part++], "boot",
149 offset, MTD_WRITEABLE);
150 continue;
151 }
152
153 /*
154 * board_data starts with board_id which differs across boards,
155 * but we can use 'MPFR' (hopefully) magic at 0x100
156 */
157 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
158 bcm47xxpart_add_part(&parts[curr_part++], "board_data",
159 offset, MTD_WRITEABLE);
160 continue;
161 }
162
163 /* Found on Huawei E970 */
164 if (buf[0x000 / 4] == FACTORY_MAGIC) {
165 bcm47xxpart_add_part(&parts[curr_part++], "factory",
166 offset, MTD_WRITEABLE);
167 continue;
168 }
169
170 /* POT(TOP) */
171 if (buf[0x000 / 4] == POT_MAGIC1 &&
172 (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
173 bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
174 MTD_WRITEABLE);
175 continue;
176 }
177
178 /* ML */
179 if (buf[0x010 / 4] == ML_MAGIC1 &&
180 buf[0x014 / 4] == ML_MAGIC2) {
181 bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
182 MTD_WRITEABLE);
183 continue;
184 }
185
186 /* TRX */
187 if (buf[0x000 / 4] == TRX_MAGIC) {
188 struct trx_header *trx;
189 uint32_t last_subpart;
190 uint32_t trx_size;
191
192 if (trx_num >= ARRAY_SIZE(trx_parts))
193 pr_warn("No enough space to store another TRX found at 0x%X\n",
194 offset);
195 else
196 trx_parts[trx_num++] = curr_part;
197 bcm47xxpart_add_part(&parts[curr_part++], "firmware",
198 offset, 0);
199
200 /*
201 * Try to find TRX size. The "length" field isn't fully
202 * reliable as it could be decreased to make CRC32 cover
203 * only part of TRX data. It's commonly used as checksum
204 * can't cover e.g. ever-changing rootfs partition.
205 * Use offsets as helpers for assuming min TRX size.
206 */
207 trx = (struct trx_header *)buf;
208 last_subpart = max3(trx->offset[0], trx->offset[1],
209 trx->offset[2]);
210 trx_size = max(trx->length, last_subpart + blocksize);
211
212 /*
213 * Skip the TRX data. Decrease offset by block size as
214 * the next loop iteration will increase it.
215 */
216 offset += roundup(trx_size, blocksize) - blocksize;
217 continue;
218 }
219
220 /* Squashfs on devices not using TRX */
221 if (le32_to_cpu(buf[0x000 / 4]) == SQUASHFS_MAGIC ||
222 buf[0x000 / 4] == SHSQ_MAGIC) {
223 bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
224 offset, 0);
225 continue;
226 }
227
228 /*
229 * New (ARM?) devices may have NVRAM in some middle block. Last
230 * block will be checked later, so skip it.
231 */
232 if (offset != master->size - blocksize &&
233 buf[0x000 / 4] == NVRAM_HEADER) {
234 bcm47xxpart_add_part(&parts[curr_part++], "nvram",
235 offset, 0);
236 continue;
237 }
238
239 /* Read middle of the block */
240 err = mtd_read(master, offset + 0x8000, 0x4, &bytes_read,
241 (uint8_t *)buf);
242 if (err && !mtd_is_bitflip(err)) {
243 pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
244 offset, err);
245 continue;
246 }
247
248 /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
249 if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
250 bcm47xxpart_add_part(&parts[curr_part++], "board_data",
251 offset, MTD_WRITEABLE);
252 continue;
253 }
254 }
255
256 /* Look for NVRAM at the end of the last block. */
257 for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
258 if (curr_part >= BCM47XXPART_MAX_PARTS) {
259 pr_warn("Reached maximum number of partitions, scanning stopped!\n");
260 break;
261 }
262
263 offset = master->size - possible_nvram_sizes[i];
264 err = mtd_read(master, offset, 0x4, &bytes_read,
265 (uint8_t *)buf);
266 if (err && !mtd_is_bitflip(err)) {
267 pr_err("mtd_read error while reading (offset 0x%X): %d\n",
268 offset, err);
269 continue;
270 }
271
272 /* Standard NVRAM */
273 if (buf[0] == NVRAM_HEADER) {
274 bcm47xxpart_add_part(&parts[curr_part++], "nvram",
275 master->size - blocksize, 0);
276 break;
277 }
278 }
279
280 kfree(buf);
281
282 /*
283 * Assume that partitions end at the beginning of the one they are
284 * followed by.
285 */
286 for (i = 0; i < curr_part; i++) {
287 u64 next_part_offset = (i < curr_part - 1) ?
288 parts[i + 1].offset : master->size;
289
290 parts[i].size = next_part_offset - parts[i].offset;
291 }
292
293 /* If there was TRX parse it now */
294 for (i = 0; i < trx_num; i++) {
295 struct mtd_partition *trx = &parts[trx_parts[i]];
296
297 if (i == bcm47xxpart_bootpartition())
298 trx->types = trx_types;
299 else
300 trx->name = "failsafe";
301 }
302
303 *pparts = parts;
304 return curr_part;
305 };
306
307 static const struct of_device_id bcm47xxpart_of_match_table[] = {
308 { .compatible = "brcm,bcm947xx-cfe-partitions" },
309 {},
310 };
311 MODULE_DEVICE_TABLE(of, bcm47xxpart_of_match_table);
312
313 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
314 .parse_fn = bcm47xxpart_parse,
315 .name = "bcm47xxpart",
316 .of_match_table = bcm47xxpart_of_match_table,
317 };
318 module_mtd_part_parser(bcm47xxpart_mtd_parser);
319
320 MODULE_LICENSE("GPL");
321 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");
322
