Root/drivers/mtd/ssfdc.c

1/*
2 * Linux driver for SSFDC Flash Translation Layer (Read only)
3 * © 2005 Eptar srl
4 * Author: Claudio Lanconelli <lanconelli.claudio@eptar.com>
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
22struct ssfdcr_record {
23    struct mtd_blktrans_dev mbd;
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
48/** CHS Table
49        1MiB 2MiB 4MiB 8MiB 16MiB 32MiB 64MiB 128MiB
50NCylinder 125 125 250 250 500 500 500 500
51NHead 4 4 4 4 4 8 8 16
52NSector 4 8 8 16 16 16 32 32
53SumSector 2,000 4,000 8,000 16,000 32,000 64,000 128,000 256,000
54SectorSize 512 512 512 512 512 512 512 512
55**/
56
57typedef 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 */
65static 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
77static 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 */
101static 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 */
106static 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) {
131                printk(KERN_WARNING
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) */
152static 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 */
167static 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 */
186static 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 */
200static 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 */
243static 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;
276            ssfdc->logic_block_map[block_address] =
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
287static 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,
317        DIV_ROUND_UP(ssfdc->map_len, MAX_PHYS_BLK_PER_ZONE));
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
354out_err:
355    kfree(ssfdc->logic_block_map);
356        kfree(ssfdc);
357}
358
359static 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
365    del_mtd_blktrans_dev(dev);
366    kfree(ssfdc->logic_block_map);
367}
368
369static 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
409static 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
429static 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
441static 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
448static void __exit cleanup_ssfdcr(void)
449{
450    deregister_mtd_blktrans(&ssfdcr_tr);
451}
452
453module_init(init_ssfdcr);
454module_exit(cleanup_ssfdcr);
455
456MODULE_LICENSE("GPL");
457MODULE_AUTHOR("Claudio Lanconelli <lanconelli.claudio@eptar.com>");
458MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");
459

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