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_is_nand(mtd) || 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