xref: /openbmc/linux/drivers/mtd/ssfdc.c (revision 745df179)
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 <lanconelli.claudio@eptar.com>
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 
19 struct ssfdcr_record {
20 	struct mtd_blktrans_dev mbd;
21 	int usecount;
22 	unsigned char heads;
23 	unsigned char sectors;
24 	unsigned short cylinders;
25 	int cis_block;			/* block n. containing CIS/IDI */
26 	int erase_size;			/* phys_block_size */
27 	unsigned short *logic_block_map; /* all zones (max 8192 phys blocks on
28 					    the 128MiB) */
29 	int map_len;			/* n. phys_blocks on the card */
30 };
31 
32 #define SSFDCR_MAJOR		257
33 #define SSFDCR_PARTN_BITS	3
34 
35 #define SECTOR_SIZE		512
36 #define SECTOR_SHIFT		9
37 #define OOB_SIZE		16
38 
39 #define MAX_LOGIC_BLK_PER_ZONE	1000
40 #define MAX_PHYS_BLK_PER_ZONE	1024
41 
42 #define KiB(x)	( (x) * 1024L )
43 #define MiB(x)	( KiB(x) * 1024L )
44 
45 /** CHS Table
46 		1MiB	2MiB	4MiB	8MiB	16MiB	32MiB	64MiB	128MiB
47 NCylinder	125	125	250	250	500	500	500	500
48 NHead		4	4	4	4	4	8	8	16
49 NSector		4	8	8	16	16	16	32	32
50 SumSector	2,000	4,000	8,000	16,000	32,000	64,000	128,000	256,000
51 SectorSize	512	512	512	512	512	512	512	512
52 **/
53 
54 typedef struct {
55 	unsigned long size;
56 	unsigned short cyl;
57 	unsigned char head;
58 	unsigned char sec;
59 } chs_entry_t;
60 
61 /* Must be ordered by size */
62 static const chs_entry_t chs_table[] = {
63 	{ MiB(  1), 125,  4,  4 },
64 	{ MiB(  2), 125,  4,  8 },
65 	{ MiB(  4), 250,  4,  8 },
66 	{ MiB(  8), 250,  4, 16 },
67 	{ MiB( 16), 500,  4, 16 },
68 	{ MiB( 32), 500,  8, 16 },
69 	{ MiB( 64), 500,  8, 32 },
70 	{ MiB(128), 500, 16, 32 },
71 	{ 0 },
72 };
73 
get_chs(unsigned long size,unsigned short * cyl,unsigned char * head,unsigned char * sec)74 static int get_chs(unsigned long size, unsigned short *cyl, unsigned char *head,
75 			unsigned char *sec)
76 {
77 	int k;
78 	int found = 0;
79 
80 	k = 0;
81 	while (chs_table[k].size > 0 && size > chs_table[k].size)
82 		k++;
83 
84 	if (chs_table[k].size > 0) {
85 		if (cyl)
86 			*cyl = chs_table[k].cyl;
87 		if (head)
88 			*head = chs_table[k].head;
89 		if (sec)
90 			*sec = chs_table[k].sec;
91 		found = 1;
92 	}
93 
94 	return found;
95 }
96 
97 /* These bytes are the signature for the CIS/IDI sector */
98 static const uint8_t cis_numbers[] = {
99 	0x01, 0x03, 0xD9, 0x01, 0xFF, 0x18, 0x02, 0xDF, 0x01, 0x20
100 };
101 
102 /* Read and check for a valid CIS sector */
get_valid_cis_sector(struct mtd_info * mtd)103 static int get_valid_cis_sector(struct mtd_info *mtd)
104 {
105 	int ret, k, cis_sector;
106 	size_t retlen;
107 	loff_t offset;
108 	uint8_t *sect_buf;
109 
110 	cis_sector = -1;
111 
112 	sect_buf = kmalloc(SECTOR_SIZE, GFP_KERNEL);
113 	if (!sect_buf)
114 		goto out;
115 
116 	/*
117 	 * Look for CIS/IDI sector on the first GOOD block (give up after 4 bad
118 	 * blocks). If the first good block doesn't contain CIS number the flash
119 	 * is not SSFDC formatted
120 	 */
121 	for (k = 0, offset = 0; k < 4; k++, offset += mtd->erasesize) {
122 		if (mtd_block_isbad(mtd, offset)) {
123 			ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen,
124 				       sect_buf);
125 
126 			/* CIS pattern match on the sector buffer */
127 			if (ret < 0 || retlen != SECTOR_SIZE) {
128 				printk(KERN_WARNING
129 					"SSFDC_RO:can't read CIS/IDI sector\n");
130 			} else if (!memcmp(sect_buf, cis_numbers,
131 					sizeof(cis_numbers))) {
132 				/* Found */
133 				cis_sector = (int)(offset >> SECTOR_SHIFT);
134 			} else {
135 				pr_debug("SSFDC_RO: CIS/IDI sector not found"
136 					" on %s (mtd%d)\n", mtd->name,
137 					mtd->index);
138 			}
139 			break;
140 		}
141 	}
142 
143 	kfree(sect_buf);
144  out:
145 	return cis_sector;
146 }
147 
148 /* Read physical sector (wrapper to MTD_READ) */
read_physical_sector(struct mtd_info * mtd,uint8_t * sect_buf,int sect_no)149 static int read_physical_sector(struct mtd_info *mtd, uint8_t *sect_buf,
150 				int sect_no)
151 {
152 	int ret;
153 	size_t retlen;
154 	loff_t offset = (loff_t)sect_no << SECTOR_SHIFT;
155 
156 	ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen, sect_buf);
157 	if (ret < 0 || retlen != SECTOR_SIZE)
158 		return -1;
159 
160 	return 0;
161 }
162 
163 /* Read redundancy area (wrapper to MTD_READ_OOB */
read_raw_oob(struct mtd_info * mtd,loff_t offs,uint8_t * buf)164 static int read_raw_oob(struct mtd_info *mtd, loff_t offs, uint8_t *buf)
165 {
166 	struct mtd_oob_ops ops = { };
167 	int ret;
168 
169 	ops.mode = MTD_OPS_RAW;
170 	ops.ooboffs = 0;
171 	ops.ooblen = OOB_SIZE;
172 	ops.oobbuf = buf;
173 	ops.datbuf = NULL;
174 
175 	ret = mtd_read_oob(mtd, offs, &ops);
176 	if (ret < 0 || ops.oobretlen != OOB_SIZE)
177 		return -1;
178 
179 	return 0;
180 }
181 
182 /* Parity calculator on a word of n bit size */
get_parity(int number,int size)183 static int get_parity(int number, int size)
184 {
185  	int k;
186 	int parity;
187 
188 	parity = 1;
189 	for (k = 0; k < size; k++) {
190 		parity += (number >> k);
191 		parity &= 1;
192 	}
193 	return parity;
194 }
195 
196 /* Read and validate the logical block address field stored in the OOB */
get_logical_address(uint8_t * oob_buf)197 static int get_logical_address(uint8_t *oob_buf)
198 {
199 	int block_address, parity;
200 	int offset[2] = {6, 11}; /* offset of the 2 address fields within OOB */
201 	int j;
202 	int ok = 0;
203 
204 	/*
205 	 * Look for the first valid logical address
206 	 * Valid address has fixed pattern on most significant bits and
207 	 * parity check
208 	 */
209 	for (j = 0; j < ARRAY_SIZE(offset); j++) {
210 		block_address = ((int)oob_buf[offset[j]] << 8) |
211 			oob_buf[offset[j]+1];
212 
213 		/* Check for the signature bits in the address field (MSBits) */
214 		if ((block_address & ~0x7FF) == 0x1000) {
215 			parity = block_address & 0x01;
216 			block_address &= 0x7FF;
217 			block_address >>= 1;
218 
219 			if (get_parity(block_address, 10) != parity) {
220 				pr_debug("SSFDC_RO: logical address field%d"
221 					"parity error(0x%04X)\n", j+1,
222 					block_address);
223 			} else {
224 				ok = 1;
225 				break;
226 			}
227 		}
228 	}
229 
230 	if (!ok)
231 		block_address = -2;
232 
233 	pr_debug("SSFDC_RO: get_logical_address() %d\n",
234 		block_address);
235 
236 	return block_address;
237 }
238 
239 /* Build the logic block map */
build_logical_block_map(struct ssfdcr_record * ssfdc)240 static int build_logical_block_map(struct ssfdcr_record *ssfdc)
241 {
242 	unsigned long offset;
243 	uint8_t oob_buf[OOB_SIZE];
244 	int ret, block_address, phys_block;
245 	struct mtd_info *mtd = ssfdc->mbd.mtd;
246 
247 	pr_debug("SSFDC_RO: build_block_map() nblks=%d (%luK)\n",
248 	      ssfdc->map_len,
249 	      (unsigned long)ssfdc->map_len * ssfdc->erase_size / 1024);
250 
251 	/* Scan every physical block, skip CIS block */
252 	for (phys_block = ssfdc->cis_block + 1; phys_block < ssfdc->map_len;
253 			phys_block++) {
254 		offset = (unsigned long)phys_block * ssfdc->erase_size;
255 		if (mtd_block_isbad(mtd, offset))
256 			continue;	/* skip bad blocks */
257 
258 		ret = read_raw_oob(mtd, offset, oob_buf);
259 		if (ret < 0) {
260 			pr_debug("SSFDC_RO: mtd read_oob() failed at %lu\n",
261 				offset);
262 			return -1;
263 		}
264 		block_address = get_logical_address(oob_buf);
265 
266 		/* Skip invalid addresses */
267 		if (block_address >= 0 &&
268 				block_address < MAX_LOGIC_BLK_PER_ZONE) {
269 			int zone_index;
270 
271 			zone_index = phys_block / MAX_PHYS_BLK_PER_ZONE;
272 			block_address += zone_index * MAX_LOGIC_BLK_PER_ZONE;
273 			ssfdc->logic_block_map[block_address] =
274 				(unsigned short)phys_block;
275 
276 			pr_debug("SSFDC_RO: build_block_map() phys_block=%d,"
277 				"logic_block_addr=%d, zone=%d\n",
278 				phys_block, block_address, zone_index);
279 		}
280 	}
281 	return 0;
282 }
283 
ssfdcr_add_mtd(struct mtd_blktrans_ops * tr,struct mtd_info * mtd)284 static void ssfdcr_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
285 {
286 	struct ssfdcr_record *ssfdc;
287 	int cis_sector;
288 
289 	/* Check for small page NAND flash */
290 	if (!mtd_type_is_nand(mtd) || mtd->oobsize != OOB_SIZE ||
291 	    mtd->size > UINT_MAX)
292 		return;
293 
294 	/* Check for SSDFC format by reading CIS/IDI sector */
295 	cis_sector = get_valid_cis_sector(mtd);
296 	if (cis_sector == -1)
297 		return;
298 
299 	ssfdc = kzalloc(sizeof(struct ssfdcr_record), GFP_KERNEL);
300 	if (!ssfdc)
301 		return;
302 
303 	ssfdc->mbd.mtd = mtd;
304 	ssfdc->mbd.devnum = -1;
305 	ssfdc->mbd.tr = tr;
306 	ssfdc->mbd.readonly = 1;
307 
308 	ssfdc->cis_block = cis_sector / (mtd->erasesize >> SECTOR_SHIFT);
309 	ssfdc->erase_size = mtd->erasesize;
310 	ssfdc->map_len = (u32)mtd->size / mtd->erasesize;
311 
312 	pr_debug("SSFDC_RO: cis_block=%d,erase_size=%d,map_len=%d,n_zones=%d\n",
313 		ssfdc->cis_block, ssfdc->erase_size, ssfdc->map_len,
314 		DIV_ROUND_UP(ssfdc->map_len, MAX_PHYS_BLK_PER_ZONE));
315 
316 	/* Set geometry */
317 	ssfdc->heads = 16;
318 	ssfdc->sectors = 32;
319 	get_chs(mtd->size, NULL, &ssfdc->heads, &ssfdc->sectors);
320 	ssfdc->cylinders = (unsigned short)(((u32)mtd->size >> SECTOR_SHIFT) /
321 			((long)ssfdc->sectors * (long)ssfdc->heads));
322 
323 	pr_debug("SSFDC_RO: using C:%d H:%d S:%d == %ld sects\n",
324 		ssfdc->cylinders, ssfdc->heads , ssfdc->sectors,
325 		(long)ssfdc->cylinders * (long)ssfdc->heads *
326 		(long)ssfdc->sectors);
327 
328 	ssfdc->mbd.size = (long)ssfdc->heads * (long)ssfdc->cylinders *
329 				(long)ssfdc->sectors;
330 
331 	/* Allocate logical block map */
332 	ssfdc->logic_block_map =
333 		kmalloc_array(ssfdc->map_len,
334 			      sizeof(ssfdc->logic_block_map[0]), GFP_KERNEL);
335 	if (!ssfdc->logic_block_map)
336 		goto out_err;
337 	memset(ssfdc->logic_block_map, 0xff, sizeof(ssfdc->logic_block_map[0]) *
338 		ssfdc->map_len);
339 
340 	/* Build logical block map */
341 	if (build_logical_block_map(ssfdc) < 0)
342 		goto out_err;
343 
344 	/* Register device + partitions */
345 	if (add_mtd_blktrans_dev(&ssfdc->mbd))
346 		goto out_err;
347 
348 	printk(KERN_INFO "SSFDC_RO: Found ssfdc%c on mtd%d (%s)\n",
349 		ssfdc->mbd.devnum + 'a', mtd->index, mtd->name);
350 	return;
351 
352 out_err:
353 	kfree(ssfdc->logic_block_map);
354         kfree(ssfdc);
355 }
356 
ssfdcr_remove_dev(struct mtd_blktrans_dev * dev)357 static 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 
ssfdcr_readsect(struct mtd_blktrans_dev * dev,unsigned long logic_sect_no,char * buf)367 static 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 
ssfdcr_getgeo(struct mtd_blktrans_dev * dev,struct hd_geometry * geo)406 static 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 
426 static 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 
init_ssfdcr(void)438 static 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 
cleanup_ssfdcr(void)445 static void __exit cleanup_ssfdcr(void)
446 {
447 	deregister_mtd_blktrans(&ssfdcr_tr);
448 }
449 
450 module_init(init_ssfdcr);
451 module_exit(cleanup_ssfdcr);
452 
453 MODULE_LICENSE("GPL");
454 MODULE_AUTHOR("Claudio Lanconelli <lanconelli.claudio@eptar.com>");
455 MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");
456