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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Linux driver for SSFDC Flash Translation Layer (Read only)
4 * © 2005 Eptar srl
5 * Author: Claudio Lanconelli <[email protected]>
6 *
7 * Based on NTFL and MTDBLOCK_RO drivers
8 */
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/slab.h>
14#include <linux/hdreg.h>
15#include <linux/mtd/mtd.h>
16#include <linux/mtd/rawnand.h>
17#include <linux/mtd/blktrans.h>
18
19struct ssfdcr_record {
20 struct mtd_blktrans_dev mbd;
21 unsigned char heads;
22 unsigned char sectors;
23 unsigned short cylinders;
24 int cis_block; /* block n. containing CIS/IDI */
25 int erase_size; /* phys_block_size */
26 unsigned short *logic_block_map; /* all zones (max 8192 phys blocks on
27 the 128MiB) */
28 int map_len; /* n. phys_blocks on the card */
29};
30
31#define SSFDCR_MAJOR 257
32#define SSFDCR_PARTN_BITS 3
33
34#define SECTOR_SIZE 512
35#define SECTOR_SHIFT 9
36#define OOB_SIZE 16
37
38#define MAX_LOGIC_BLK_PER_ZONE 1000
39#define MAX_PHYS_BLK_PER_ZONE 1024
40
41#define KiB(x) ( (x) * 1024L )
42#define MiB(x) ( KiB(x) * 1024L )
43
44/** CHS Table
45 1MiB 2MiB 4MiB 8MiB 16MiB 32MiB 64MiB 128MiB
46NCylinder 125 125 250 250 500 500 500 500
47NHead 4 4 4 4 4 8 8 16
48NSector 4 8 8 16 16 16 32 32
49SumSector 2,000 4,000 8,000 16,000 32,000 64,000 128,000 256,000
50SectorSize 512 512 512 512 512 512 512 512
51**/
52
53typedef struct {
54 unsigned long size;
55 unsigned short cyl;
56 unsigned char head;
57 unsigned char sec;
58} chs_entry_t;
59
60/* Must be ordered by size */
61static const chs_entry_t chs_table[] = {
62 { MiB( 1), 125, 4, 4 },
63 { MiB( 2), 125, 4, 8 },
64 { MiB( 4), 250, 4, 8 },
65 { MiB( 8), 250, 4, 16 },
66 { MiB( 16), 500, 4, 16 },
67 { MiB( 32), 500, 8, 16 },
68 { MiB( 64), 500, 8, 32 },
69 { MiB(128), 500, 16, 32 },
70 { 0 },
71};
72
73static int get_chs(unsigned long size, unsigned short *cyl, unsigned char *head,
74 unsigned char *sec)
75{
76 int k;
77 int found = 0;
78
79 k = 0;
80 while (chs_table[k].size > 0 && size > chs_table[k].size)
81 k++;
82
83 if (chs_table[k].size > 0) {
84 if (cyl)
85 *cyl = chs_table[k].cyl;
86 if (head)
87 *head = chs_table[k].head;
88 if (sec)
89 *sec = chs_table[k].sec;
90 found = 1;
91 }
92
93 return found;
94}
95
96/* These bytes are the signature for the CIS/IDI sector */
97static const uint8_t cis_numbers[] = {
98 0x01, 0x03, 0xD9, 0x01, 0xFF, 0x18, 0x02, 0xDF, 0x01, 0x20
99};
100
101/* Read and check for a valid CIS sector */
102static int get_valid_cis_sector(struct mtd_info *mtd)
103{
104 int ret, k, cis_sector;
105 size_t retlen;
106 loff_t offset;
107 uint8_t *sect_buf;
108
109 cis_sector = -1;
110
111 sect_buf = kmalloc(SECTOR_SIZE, GFP_KERNEL);
112 if (!sect_buf)
113 goto out;
114
115 /*
116 * Look for CIS/IDI sector on the first GOOD block (give up after 4 bad
117 * blocks). If the first good block doesn't contain CIS number the flash
118 * is not SSFDC formatted
119 */
120 for (k = 0, offset = 0; k < 4; k++, offset += mtd->erasesize) {
121 if (mtd_block_isbad(mtd, offset)) {
122 ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen,
123 sect_buf);
124
125 /* CIS pattern match on the sector buffer */
126 if (ret < 0 || retlen != SECTOR_SIZE) {
127 printk(KERN_WARNING
128 "SSFDC_RO:can't read CIS/IDI sector\n");
129 } else if (!memcmp(sect_buf, cis_numbers,
130 sizeof(cis_numbers))) {
131 /* Found */
132 cis_sector = (int)(offset >> SECTOR_SHIFT);
133 } else {
134 pr_debug("SSFDC_RO: CIS/IDI sector not found"
135 " on %s (mtd%d)\n", mtd->name,
136 mtd->index);
137 }
138 break;
139 }
140 }
141
142 kfree(sect_buf);
143 out:
144 return cis_sector;
145}
146
147/* Read physical sector (wrapper to MTD_READ) */
148static int read_physical_sector(struct mtd_info *mtd, uint8_t *sect_buf,
149 int sect_no)
150{
151 int ret;
152 size_t retlen;
153 loff_t offset = (loff_t)sect_no << SECTOR_SHIFT;
154
155 ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen, sect_buf);
156 if (ret < 0 || retlen != SECTOR_SIZE)
157 return -1;
158
159 return 0;
160}
161
162/* Read redundancy area (wrapper to MTD_READ_OOB */
163static int read_raw_oob(struct mtd_info *mtd, loff_t offs, uint8_t *buf)
164{
165 struct mtd_oob_ops ops = { };
166 int ret;
167
168 ops.mode = MTD_OPS_RAW;
169 ops.ooboffs = 0;
170 ops.ooblen = OOB_SIZE;
171 ops.oobbuf = buf;
172 ops.datbuf = NULL;
173
174 ret = mtd_read_oob(mtd, offs, &ops);
175 if (ret < 0 || ops.oobretlen != OOB_SIZE)
176 return -1;
177
178 return 0;
179}
180
181/* Parity calculator on a word of n bit size */
182static int get_parity(int number, int size)
183{
184 int k;
185 int parity;
186
187 parity = 1;
188 for (k = 0; k < size; k++) {
189 parity += (number >> k);
190 parity &= 1;
191 }
192 return parity;
193}
194
195/* Read and validate the logical block address field stored in the OOB */
196static int get_logical_address(uint8_t *oob_buf)
197{
198 int block_address, parity;
199 int offset[2] = {6, 11}; /* offset of the 2 address fields within OOB */
200 int j;
201 int ok = 0;
202
203 /*
204 * Look for the first valid logical address
205 * Valid address has fixed pattern on most significant bits and
206 * parity check
207 */
208 for (j = 0; j < ARRAY_SIZE(offset); j++) {
209 block_address = ((int)oob_buf[offset[j]] << 8) |
210 oob_buf[offset[j]+1];
211
212 /* Check for the signature bits in the address field (MSBits) */
213 if ((block_address & ~0x7FF) == 0x1000) {
214 parity = block_address & 0x01;
215 block_address &= 0x7FF;
216 block_address >>= 1;
217
218 if (get_parity(block_address, 10) != parity) {
219 pr_debug("SSFDC_RO: logical address field%d"
220 "parity error(0x%04X)\n", j+1,
221 block_address);
222 } else {
223 ok = 1;
224 break;
225 }
226 }
227 }
228
229 if (!ok)
230 block_address = -2;
231
232 pr_debug("SSFDC_RO: get_logical_address() %d\n",
233 block_address);
234
235 return block_address;
236}
237
238/* Build the logic block map */
239static int build_logical_block_map(struct ssfdcr_record *ssfdc)
240{
241 unsigned long offset;
242 uint8_t oob_buf[OOB_SIZE];
243 int ret, block_address, phys_block;
244 struct mtd_info *mtd = ssfdc->mbd.mtd;
245
246 pr_debug("SSFDC_RO: build_block_map() nblks=%d (%luK)\n",
247 ssfdc->map_len,
248 (unsigned long)ssfdc->map_len * ssfdc->erase_size / 1024);
249
250 /* Scan every physical block, skip CIS block */
251 for (phys_block = ssfdc->cis_block + 1; phys_block < ssfdc->map_len;
252 phys_block++) {
253 offset = (unsigned long)phys_block * ssfdc->erase_size;
254 if (mtd_block_isbad(mtd, offset))
255 continue; /* skip bad blocks */
256
257 ret = read_raw_oob(mtd, offset, oob_buf);
258 if (ret < 0) {
259 pr_debug("SSFDC_RO: mtd read_oob() failed at %lu\n",
260 offset);
261 return -1;
262 }
263 block_address = get_logical_address(oob_buf);
264
265 /* Skip invalid addresses */
266 if (block_address >= 0 &&
267 block_address < MAX_LOGIC_BLK_PER_ZONE) {
268 int zone_index;
269
270 zone_index = phys_block / MAX_PHYS_BLK_PER_ZONE;
271 block_address += zone_index * MAX_LOGIC_BLK_PER_ZONE;
272 ssfdc->logic_block_map[block_address] =
273 (unsigned short)phys_block;
274
275 pr_debug("SSFDC_RO: build_block_map() phys_block=%d,"
276 "logic_block_addr=%d, zone=%d\n",
277 phys_block, block_address, zone_index);
278 }
279 }
280 return 0;
281}
282
283static void ssfdcr_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
284{
285 struct ssfdcr_record *ssfdc;
286 int cis_sector;
287
288 /* Check for small page NAND flash */
289 if (!mtd_type_is_nand(mtd) || mtd->oobsize != OOB_SIZE ||
290 mtd->size > UINT_MAX)
291 return;
292
293 /* Check for SSDFC format by reading CIS/IDI sector */
294 cis_sector = get_valid_cis_sector(mtd);
295 if (cis_sector == -1)
296 return;
297
298 ssfdc = kzalloc_obj(*ssfdc);
299 if (!ssfdc)
300 return;
301
302 ssfdc->mbd.mtd = mtd;
303 ssfdc->mbd.devnum = -1;
304 ssfdc->mbd.tr = tr;
305 ssfdc->mbd.readonly = 1;
306
307 ssfdc->cis_block = cis_sector / (mtd->erasesize >> SECTOR_SHIFT);
308 ssfdc->erase_size = mtd->erasesize;
309 ssfdc->map_len = (u32)mtd->size / mtd->erasesize;
310
311 pr_debug("SSFDC_RO: cis_block=%d,erase_size=%d,map_len=%d,n_zones=%d\n",
312 ssfdc->cis_block, ssfdc->erase_size, ssfdc->map_len,
313 DIV_ROUND_UP(ssfdc->map_len, MAX_PHYS_BLK_PER_ZONE));
314
315 /* Set geometry */
316 ssfdc->heads = 16;
317 ssfdc->sectors = 32;
318 get_chs(mtd->size, NULL, &ssfdc->heads, &ssfdc->sectors);
319 ssfdc->cylinders = (unsigned short)(((u32)mtd->size >> SECTOR_SHIFT) /
320 ((long)ssfdc->sectors * (long)ssfdc->heads));
321
322 pr_debug("SSFDC_RO: using C:%d H:%d S:%d == %ld sects\n",
323 ssfdc->cylinders, ssfdc->heads , ssfdc->sectors,
324 (long)ssfdc->cylinders * (long)ssfdc->heads *
325 (long)ssfdc->sectors);
326
327 ssfdc->mbd.size = (long)ssfdc->heads * (long)ssfdc->cylinders *
328 (long)ssfdc->sectors;
329
330 /* Allocate logical block map */
331 ssfdc->logic_block_map =
332 kmalloc_array(ssfdc->map_len,
333 sizeof(ssfdc->logic_block_map[0]), GFP_KERNEL);
334 if (!ssfdc->logic_block_map)
335 goto out_free_ssfdc;
336 memset(ssfdc->logic_block_map, 0xff, sizeof(ssfdc->logic_block_map[0]) *
337 ssfdc->map_len);
338
339 /* Build logical block map */
340 if (build_logical_block_map(ssfdc) < 0)
341 goto out_err;
342
343 /* Register device + partitions */
344 if (add_mtd_blktrans_dev(&ssfdc->mbd))
345 goto out_err;
346
347 printk(KERN_INFO "SSFDC_RO: Found ssfdc%c on mtd%d (%s)\n",
348 ssfdc->mbd.devnum + 'a', mtd->index, mtd->name);
349 return;
350
351out_err:
352 kfree(ssfdc->logic_block_map);
353out_free_ssfdc:
354 kfree(ssfdc);
355}
356
357static void ssfdcr_remove_dev(struct mtd_blktrans_dev *dev)
358{
359 struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
360
361 pr_debug("SSFDC_RO: remove_dev (i=%d)\n", dev->devnum);
362
363 del_mtd_blktrans_dev(dev);
364 kfree(ssfdc->logic_block_map);
365}
366
367static int ssfdcr_readsect(struct mtd_blktrans_dev *dev,
368 unsigned long logic_sect_no, char *buf)
369{
370 struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
371 int sectors_per_block, offset, block_address;
372
373 sectors_per_block = ssfdc->erase_size >> SECTOR_SHIFT;
374 offset = (int)(logic_sect_no % sectors_per_block);
375 block_address = (int)(logic_sect_no / sectors_per_block);
376
377 pr_debug("SSFDC_RO: ssfdcr_readsect(%lu) sec_per_blk=%d, ofst=%d,"
378 " block_addr=%d\n", logic_sect_no, sectors_per_block, offset,
379 block_address);
380
381 BUG_ON(block_address >= ssfdc->map_len);
382
383 block_address = ssfdc->logic_block_map[block_address];
384
385 pr_debug("SSFDC_RO: ssfdcr_readsect() phys_block_addr=%d\n",
386 block_address);
387
388 if (block_address < 0xffff) {
389 unsigned long sect_no;
390
391 sect_no = (unsigned long)block_address * sectors_per_block +
392 offset;
393
394 pr_debug("SSFDC_RO: ssfdcr_readsect() phys_sect_no=%lu\n",
395 sect_no);
396
397 if (read_physical_sector(ssfdc->mbd.mtd, buf, sect_no) < 0)
398 return -EIO;
399 } else {
400 memset(buf, 0xff, SECTOR_SIZE);
401 }
402
403 return 0;
404}
405
406static int ssfdcr_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo)
407{
408 struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
409
410 pr_debug("SSFDC_RO: ssfdcr_getgeo() C=%d, H=%d, S=%d\n",
411 ssfdc->cylinders, ssfdc->heads, ssfdc->sectors);
412
413 geo->heads = ssfdc->heads;
414 geo->sectors = ssfdc->sectors;
415 geo->cylinders = ssfdc->cylinders;
416
417 return 0;
418}
419
420/****************************************************************************
421 *
422 * Module stuff
423 *
424 ****************************************************************************/
425
426static struct mtd_blktrans_ops ssfdcr_tr = {
427 .name = "ssfdc",
428 .major = SSFDCR_MAJOR,
429 .part_bits = SSFDCR_PARTN_BITS,
430 .blksize = SECTOR_SIZE,
431 .getgeo = ssfdcr_getgeo,
432 .readsect = ssfdcr_readsect,
433 .add_mtd = ssfdcr_add_mtd,
434 .remove_dev = ssfdcr_remove_dev,
435 .owner = THIS_MODULE,
436};
437
438static int __init init_ssfdcr(void)
439{
440 printk(KERN_INFO "SSFDC read-only Flash Translation layer\n");
441
442 return register_mtd_blktrans(&ssfdcr_tr);
443}
444
445static void __exit cleanup_ssfdcr(void)
446{
447 deregister_mtd_blktrans(&ssfdcr_tr);
448}
449
450module_init(init_ssfdcr);
451module_exit(cleanup_ssfdcr);
452
453MODULE_LICENSE("GPL");
454MODULE_AUTHOR("Claudio Lanconelli <[email protected]>");
455MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");