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