aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/mtd/nand/rtc_from4.c
blob: 26f88215bc47d48c12ff9768da72829366d4ac76 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
/*
 *  drivers/mtd/nand/rtc_from4.c
 *
 *  Copyright (C) 2004  Red Hat, Inc.
 *
 *  Derived from drivers/mtd/nand/spia.c
 *       Copyright (C) 2000 Steven J. Hill (sjhill@realitydiluted.com)
 *
 * $Id: rtc_from4.c,v 1.10 2005/11/07 11:14:31 gleixner Exp $
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Overview:
 *   This is a device driver for the AG-AND flash device found on the
 *   Renesas Technology Corp. Flash ROM 4-slot interface board (FROM_BOARD4),
 *   which utilizes the Renesas HN29V1G91T-30 part.
 *   This chip is a 1 GBibit (128MiB x 8 bits) AG-AND flash device.
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/rslib.h>
#include <linux/bitrev.h>
#include <linux/module.h>
#include <linux/mtd/compatmac.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>
#include <asm/io.h>

/*
 * MTD structure for Renesas board
 */
static struct mtd_info *rtc_from4_mtd = NULL;

#define RTC_FROM4_MAX_CHIPS	2

/* HS77x9 processor register defines */
#define SH77X9_BCR1	((volatile unsigned short *)(0xFFFFFF60))
#define SH77X9_BCR2	((volatile unsigned short *)(0xFFFFFF62))
#define SH77X9_WCR1	((volatile unsigned short *)(0xFFFFFF64))
#define SH77X9_WCR2	((volatile unsigned short *)(0xFFFFFF66))
#define SH77X9_MCR	((volatile unsigned short *)(0xFFFFFF68))
#define SH77X9_PCR	((volatile unsigned short *)(0xFFFFFF6C))
#define SH77X9_FRQCR	((volatile unsigned short *)(0xFFFFFF80))

/*
 * Values specific to the Renesas Technology Corp. FROM_BOARD4 (used with HS77x9 processor)
 */
/* Address where flash is mapped */
#define RTC_FROM4_FIO_BASE	0x14000000

/* CLE and ALE are tied to address lines 5 & 4, respectively */
#define RTC_FROM4_CLE		(1 << 5)
#define RTC_FROM4_ALE		(1 << 4)

/* address lines A24-A22 used for chip selection */
#define RTC_FROM4_NAND_ADDR_SLOT3	(0x00800000)
#define RTC_FROM4_NAND_ADDR_SLOT4	(0x00C00000)
#define RTC_FROM4_NAND_ADDR_FPGA	(0x01000000)
/* mask address lines A24-A22 used for chip selection */
#define RTC_FROM4_NAND_ADDR_MASK	(RTC_FROM4_NAND_ADDR_SLOT3 | RTC_FROM4_NAND_ADDR_SLOT4 | RTC_FROM4_NAND_ADDR_FPGA)

/* FPGA status register for checking device ready (bit zero) */
#define RTC_FROM4_FPGA_SR		(RTC_FROM4_NAND_ADDR_FPGA | 0x00000002)
#define RTC_FROM4_DEVICE_READY		0x0001

/* FPGA Reed-Solomon ECC Control register */

#define RTC_FROM4_RS_ECC_CTL		(RTC_FROM4_NAND_ADDR_FPGA | 0x00000050)
#define RTC_FROM4_RS_ECC_CTL_CLR	(1 << 7)
#define RTC_FROM4_RS_ECC_CTL_GEN	(1 << 6)
#define RTC_FROM4_RS_ECC_CTL_FD_E	(1 << 5)

/* FPGA Reed-Solomon ECC code base */
#define RTC_FROM4_RS_ECC		(RTC_FROM4_NAND_ADDR_FPGA | 0x00000060)
#define RTC_FROM4_RS_ECCN		(RTC_FROM4_NAND_ADDR_FPGA | 0x00000080)

/* FPGA Reed-Solomon ECC check register */
#define RTC_FROM4_RS_ECC_CHK		(RTC_FROM4_NAND_ADDR_FPGA | 0x00000070)
#define RTC_FROM4_RS_ECC_CHK_ERROR	(1 << 7)

#define ERR_STAT_ECC_AVAILABLE		0x20

/* Undefine for software ECC */
#define RTC_FROM4_HWECC	1

/* Define as 1 for no virtual erase blocks (in JFFS2) */
#define RTC_FROM4_NO_VIRTBLOCKS	0

/*
 * Module stuff
 */
static void __iomem *rtc_from4_fio_base = (void *)P2SEGADDR(RTC_FROM4_FIO_BASE);

static const struct mtd_partition partition_info[] = {
	{
	 .name = "Renesas flash partition 1",
	 .offset = 0,
	 .size = MTDPART_SIZ_FULL},
};

#define NUM_PARTITIONS 1

/*
 *	hardware specific flash bbt decriptors
 *	Note: this is to allow debugging by disabling
 *		NAND_BBT_CREATE and/or NAND_BBT_WRITE
 *
 */
static uint8_t bbt_pattern[] = { 'B', 'b', 't', '0' };
static uint8_t mirror_pattern[] = { '1', 't', 'b', 'B' };

static struct nand_bbt_descr rtc_from4_bbt_main_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
	.offs = 40,
	.len = 4,
	.veroffs = 44,
	.maxblocks = 4,
	.pattern = bbt_pattern
};

static struct nand_bbt_descr rtc_from4_bbt_mirror_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
	.offs = 40,
	.len = 4,
	.veroffs = 44,
	.maxblocks = 4,
	.pattern = mirror_pattern
};

#ifdef RTC_FROM4_HWECC

/* the Reed Solomon control structure */
static struct rs_control *rs_decoder;

/*
 *      hardware specific Out Of Band information
 */
static struct nand_ecclayout rtc_from4_nand_oobinfo = {
	.eccbytes = 32,
	.eccpos = {
		   0, 1, 2, 3, 4, 5, 6, 7,
		   8, 9, 10, 11, 12, 13, 14, 15,
		   16, 17, 18, 19, 20, 21, 22, 23,
		   24, 25, 26, 27, 28, 29, 30, 31},
	.oobfree = {{32, 32}}
};

#endif

/*
 * rtc_from4_hwcontrol - hardware specific access to control-lines
 * @mtd:	MTD device structure
 * @cmd:	hardware control command
 *
 * Address lines (A5 and A4) are used to control Command and Address Latch
 * Enable on this board, so set the read/write address appropriately.
 *
 * Chip Enable is also controlled by the Chip Select (CS5) and
 * Address lines (A24-A22), so no action is required here.
 *
 */
static void rtc_from4_hwcontrol(struct mtd_info *mtd, int cmd,
				unsigned int ctrl)
{
	struct nand_chip *chip = (mtd->priv);

	if (cmd == NAND_CMD_NONE)
		return;

	if (ctrl & NAND_CLE)
		writeb(cmd, chip->IO_ADDR_W | RTC_FROM4_CLE);
	else
		writeb(cmd, chip->IO_ADDR_W | RTC_FROM4_ALE);
}

/*
 * rtc_from4_nand_select_chip - hardware specific chip select
 * @mtd:	MTD device structure
 * @chip:	Chip to select (0 == slot 3, 1 == slot 4)
 *
 * The chip select is based on address lines A24-A22.
 * This driver uses flash slots 3 and 4 (A23-A22).
 *
 */
static void rtc_from4_nand_select_chip(struct mtd_info *mtd, int chip)
{
	struct nand_chip *this = mtd->priv;

	this->IO_ADDR_R = (void __iomem *)((unsigned long)this->IO_ADDR_R & ~RTC_FROM4_NAND_ADDR_MASK);
	this->IO_ADDR_W = (void __iomem *)((unsigned long)this->IO_ADDR_W & ~RTC_FROM4_NAND_ADDR_MASK);

	switch (chip) {

	case 0:		/* select slot 3 chip */
		this->IO_ADDR_R = (void __iomem *)((unsigned long)this->IO_ADDR_R | RTC_FROM4_NAND_ADDR_SLOT3);
		this->IO_ADDR_W = (void __iomem *)((unsigned long)this->IO_ADDR_W | RTC_FROM4_NAND_ADDR_SLOT3);
		break;
	case 1:		/* select slot 4 chip */
		this->IO_ADDR_R = (void __iomem *)((unsigned long)this->IO_ADDR_R | RTC_FROM4_NAND_ADDR_SLOT4);
		this->IO_ADDR_W = (void __iomem *)((unsigned long)this->IO_ADDR_W | RTC_FROM4_NAND_ADDR_SLOT4);
		break;

	}
}

/*
 * rtc_from4_nand_device_ready - hardware specific ready/busy check
 * @mtd:	MTD device structure
 *
 * This board provides the Ready/Busy state in the status register
 * of the FPGA.  Bit zero indicates the RDY(1)/BSY(0) signal.
 *
 */
static int rtc_from4_nand_device_ready(struct mtd_info *mtd)
{
	unsigned short status;

	status = *((volatile unsigned short *)(rtc_from4_fio_base + RTC_FROM4_FPGA_SR));

	return (status & RTC_FROM4_DEVICE_READY);

}

/*
 * deplete - code to perform device recovery in case there was a power loss
 * @mtd:	MTD device structure
 * @chip:	Chip to select (0 == slot 3, 1 == slot 4)
 *
 * If there was a sudden loss of power during an erase operation, a
 * "device recovery" operation must be performed when power is restored
 * to ensure correct operation.  This routine performs the required steps
 * for the requested chip.
 *
 * See page 86 of the data sheet for details.
 *
 */
static void deplete(struct mtd_info *mtd, int chip)
{
	struct nand_chip *this = mtd->priv;

	/* wait until device is ready */
	while (!this->dev_ready(mtd)) ;

	this->select_chip(mtd, chip);

	/* Send the commands for device recovery, phase 1 */
	this->cmdfunc(mtd, NAND_CMD_DEPLETE1, 0x0000, 0x0000);
	this->cmdfunc(mtd, NAND_CMD_DEPLETE2, -1, -1);

	/* Send the commands for device recovery, phase 2 */
	this->cmdfunc(mtd, NAND_CMD_DEPLETE1, 0x0000, 0x0004);
	this->cmdfunc(mtd, NAND_CMD_DEPLETE2, -1, -1);

}

#ifdef RTC_FROM4_HWECC
/*
 * rtc_from4_enable_hwecc - hardware specific hardware ECC enable function
 * @mtd:	MTD device structure
 * @mode:	I/O mode; read or write
 *
 * enable hardware ECC for data read or write
 *
 */
static void rtc_from4_enable_hwecc(struct mtd_info *mtd, int mode)
{
	volatile unsigned short *rs_ecc_ctl = (volatile unsigned short *)(rtc_from4_fio_base + RTC_FROM4_RS_ECC_CTL);
	unsigned short status;

	switch (mode) {
	case NAND_ECC_READ:
		status = RTC_FROM4_RS_ECC_CTL_CLR | RTC_FROM4_RS_ECC_CTL_FD_E;

		*rs_ecc_ctl = status;
		break;

	case NAND_ECC_READSYN:
		status = 0x00;

		*rs_ecc_ctl = status;
		break;

	case NAND_ECC_WRITE:
		status = RTC_FROM4_RS_ECC_CTL_CLR | RTC_FROM4_RS_ECC_CTL_GEN | RTC_FROM4_RS_ECC_CTL_FD_E;

		*rs_ecc_ctl = status;
		break;

	default:
		BUG();
		break;
	}

}

/*
 * rtc_from4_calculate_ecc - hardware specific code to read ECC code
 * @mtd:	MTD device structure
 * @dat:	buffer containing the data to generate ECC codes
 * @ecc_code	ECC codes calculated
 *
 * The ECC code is calculated by the FPGA.  All we have to do is read the values
 * from the FPGA registers.
 *
 * Note: We read from the inverted registers, since data is inverted before
 * the code is calculated. So all 0xff data (blank page) results in all 0xff rs code
 *
 */
static void rtc_from4_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u_char *ecc_code)
{
	volatile unsigned short *rs_eccn = (volatile unsigned short *)(rtc_from4_fio_base + RTC_FROM4_RS_ECCN);
	unsigned short value;
	int i;

	for (i = 0; i < 8; i++) {
		value = *rs_eccn;
		ecc_code[i] = (unsigned char)value;
		rs_eccn++;
	}
	ecc_code[7] |= 0x0f;	/* set the last four bits (not used) */
}

/*
 * rtc_from4_correct_data - hardware specific code to correct data using ECC code
 * @mtd:	MTD device structure
 * @buf:	buffer containing the data to generate ECC codes
 * @ecc1	ECC codes read
 * @ecc2	ECC codes calculated
 *
 * The FPGA tells us fast, if there's an error or not. If no, we go back happy
 * else we read the ecc results from the fpga and call the rs library to decode
 * and hopefully correct the error.
 *
 */
static int rtc_from4_correct_data(struct mtd_info *mtd, const u_char *buf, u_char *ecc1, u_char *ecc2)
{
	int i, j, res;
	unsigned short status;
	uint16_t par[6], syn[6];
	uint8_t ecc[8];
	volatile unsigned short *rs_ecc;

	status = *((volatile unsigned short *)(rtc_from4_fio_base + RTC_FROM4_RS_ECC_CHK));

	if (!(status & RTC_FROM4_RS_ECC_CHK_ERROR)) {
		return 0;
	}

	/* Read the syndrom pattern from the FPGA and correct the bitorder */
	rs_ecc = (volatile unsigned short *)(rtc_from4_fio_base + RTC_FROM4_RS_ECC);
	for (i = 0; i < 8; i++) {
		ecc[i] = bitrev8(*rs_ecc);
		rs_ecc++;
	}

	/* convert into 6 10bit syndrome fields */
	par[5] = rs_decoder->index_of[(((uint16_t) ecc[0] >> 0) & 0x0ff) | (((uint16_t) ecc[1] << 8) & 0x300)];
	par[4] = rs_decoder->index_of[(((uint16_t) ecc[1] >> 2) & 0x03f) | (((uint16_t) ecc[2] << 6) & 0x3c0)];
	par[3] = rs_decoder->index_of[(((uint16_t) ecc[2] >> 4) & 0x00f) | (((uint16_t) ecc[3] << 4) & 0x3f0)];
	par[2] = rs_decoder->index_of[(((uint16_t) ecc[3] >> 6) & 0x003) | (((uint16_t) ecc[4] << 2) & 0x3fc)];
	par[1] = rs_decoder->index_of[(((uint16_t) ecc[5] >> 0) & 0x0ff) | (((uint16_t) ecc[6] << 8) & 0x300)];
	par[0] = (((uint16_t) ecc[6] >> 2) & 0x03f) | (((uint16_t) ecc[7] << 6) & 0x3c0);

	/* Convert to computable syndrome */
	for (i = 0; i < 6; i++) {
		syn[i] = par[0];
		for (j = 1; j < 6; j++)
			if (par[j] != rs_decoder->nn)
				syn[i] ^= rs_decoder->alpha_to[rs_modnn(rs_decoder, par[j] + i * j)];

		/* Convert to index form */
		syn[i] = rs_decoder->index_of[syn[i]];
	}

	/* Let the library code do its magic. */
	res = decode_rs8(rs_decoder, (uint8_t *) buf, par, 512, syn, 0, NULL, 0xff, NULL);
	if (res > 0) {
		DEBUG(MTD_DEBUG_LEVEL0, "rtc_from4_correct_data: " "ECC corrected %d errors on read\n", res);
	}
	return res;
}

/**
 * rtc_from4_errstat - perform additional error status checks
 * @mtd:	MTD device structure
 * @this:	NAND chip structure
 * @state:	state or the operation
 * @status:	status code returned from read status
 * @page:	startpage inside the chip, must be called with (page & this->pagemask)
 *
 * Perform additional error status checks on erase and write failures
 * to determine if errors are correctable.  For this device, correctable
 * 1-bit errors on erase and write are considered acceptable.
 *
 * note: see pages 34..37 of data sheet for details.
 *
 */
static int rtc_from4_errstat(struct mtd_info *mtd, struct nand_chip *this,
			     int state, int status, int page)
{
	int er_stat = 0;
	int rtn, retlen;
	size_t len;
	uint8_t *buf;
	int i;

	this->cmdfunc(mtd, NAND_CMD_STATUS_CLEAR, -1, -1);

	if (state == FL_ERASING) {

		for (i = 0; i < 4; i++) {
			if (!(status & 1 << (i + 1)))
				continue;
			this->cmdfunc(mtd, (NAND_CMD_STATUS_ERROR + i + 1),
				      -1, -1);
			rtn = this->read_byte(mtd);
			this->cmdfunc(mtd, NAND_CMD_STATUS_RESET, -1, -1);

			/* err_ecc_not_avail */
			if (!(rtn & ERR_STAT_ECC_AVAILABLE))
				er_stat |= 1 << (i + 1);
		}

	} else if (state == FL_WRITING) {

		unsigned long corrected = mtd->ecc_stats.corrected;

		/* single bank write logic */
		this->cmdfunc(mtd, NAND_CMD_STATUS_ERROR, -1, -1);
		rtn = this->read_byte(mtd);
		this->cmdfunc(mtd, NAND_CMD_STATUS_RESET, -1, -1);

		if (!(rtn & ERR_STAT_ECC_AVAILABLE)) {
			/* err_ecc_not_avail */
			er_stat |= 1 << 1;
			goto out;
		}

		len = mtd->writesize;
		buf = kmalloc(len, GFP_KERNEL);
		if (!buf) {
			printk(KERN_ERR "rtc_from4_errstat: Out of memory!\n");
			er_stat = 1;
			goto out;
		}

		/* recovery read */
		rtn = nand_do_read(mtd, page, len, &retlen, buf);

		/* if read failed or > 1-bit error corrected */
		if (rtn || (mtd->ecc_stats.corrected - corrected) > 1)
			er_stat |= 1 << 1;
		kfree(buf);
	}
out:
	rtn = status;
	if (er_stat == 0) {	/* if ECC is available   */
		rtn = (status & ~NAND_STATUS_FAIL);	/*   clear the error bit */
	}

	return rtn;
}
#endif

/*
 * Main initialization routine
 */
static int __init rtc_from4_init(void)
{
	struct nand_chip *this;
	unsigned short bcr1, bcr2, wcr2;
	int i;
	int ret;

	/* Allocate memory for MTD device structure and private data */
	rtc_from4_mtd = kmalloc(sizeof(struct mtd_info) + sizeof(struct nand_chip), GFP_KERNEL);
	if (!rtc_from4_mtd) {
		printk("Unable to allocate Renesas NAND MTD device structure.\n");
		return -ENOMEM;
	}

	/* Get pointer to private data */
	this = (struct nand_chip *)(&rtc_from4_mtd[1]);

	/* Initialize structures */
	memset(rtc_from4_mtd, 0, sizeof(struct mtd_info));
	memset(this, 0, sizeof(struct nand_chip));

	/* Link the private data with the MTD structure */
	rtc_from4_mtd->priv = this;
	rtc_from4_mtd->owner = THIS_MODULE;

	/* set area 5 as PCMCIA mode to clear the spec of tDH(Data hold time;9ns min) */
	bcr1 = *SH77X9_BCR1 & ~0x0002;
	bcr1 |= 0x0002;
	*SH77X9_BCR1 = bcr1;

	/* set */
	bcr2 = *SH77X9_BCR2 & ~0x0c00;
	bcr2 |= 0x0800;
	*SH77X9_BCR2 = bcr2;

	/* set area 5 wait states */
	wcr2 = *SH77X9_WCR2 & ~0x1c00;
	wcr2 |= 0x1c00;
	*SH77X9_WCR2 = wcr2;

	/* Set address of NAND IO lines */
	this->IO_ADDR_R = rtc_from4_fio_base;
	this->IO_ADDR_W = rtc_from4_fio_base;
	/* Set address of hardware control function */
	this->cmd_ctrl = rtc_from4_hwcontrol;
	/* Set address of chip select function */
	this->select_chip = rtc_from4_nand_select_chip;
	/* command delay time (in us) */
	this->chip_delay = 100;
	/* return the status of the Ready/Busy line */
	this->dev_ready = rtc_from4_nand_device_ready;

#ifdef RTC_FROM4_HWECC
	printk(KERN_INFO "rtc_from4_init: using hardware ECC detection.\n");

	this->ecc.mode = NAND_ECC_HW_SYNDROME;
	this->ecc.size = 512;
	this->ecc.bytes = 8;
	/* return the status of extra status and ECC checks */
	this->errstat = rtc_from4_errstat;
	/* set the nand_oobinfo to support FPGA H/W error detection */
	this->ecc.layout = &rtc_from4_nand_oobinfo;
	this->ecc.hwctl = rtc_from4_enable_hwecc;
	this->ecc.calculate = rtc_from4_calculate_ecc;
	this->ecc.correct = rtc_from4_correct_data;

	/* We could create the decoder on demand, if memory is a concern.
	 * This way we have it handy, if an error happens
	 *
	 * Symbolsize is 10 (bits)
	 * Primitve polynomial is x^10+x^3+1
	 * first consecutive root is 0
	 * primitve element to generate roots = 1
	 * generator polinomial degree = 6
	 */
	rs_decoder = init_rs(10, 0x409, 0, 1, 6);
	if (!rs_decoder) {
		printk(KERN_ERR "Could not create a RS decoder\n");
		ret = -ENOMEM;
		goto err_1;
	}
#else
	printk(KERN_INFO "rtc_from4_init: using software ECC detection.\n");

	this->ecc.mode = NAND_ECC_SOFT;
#endif

	/* set the bad block tables to support debugging */
	this->bbt_td = &rtc_from4_bbt_main_descr;
	this->bbt_md = &rtc_from4_bbt_mirror_descr;

	/* Scan to find existence of the device */
	if (nand_scan(rtc_from4_mtd, RTC_FROM4_MAX_CHIPS)) {
		ret = -ENXIO;
		goto err_2;
	}

	/* Perform 'device recovery' for each chip in case there was a power loss. */
	for (i = 0; i < this->numchips; i++) {
		deplete(rtc_from4_mtd, i);
	}

#if RTC_FROM4_NO_VIRTBLOCKS
	/* use a smaller erase block to minimize wasted space when a block is bad */
	/* note: this uses eight times as much RAM as using the default and makes */
	/*       mounts take four times as long. */
	rtc_from4_mtd->flags |= MTD_NO_VIRTBLOCKS;
#endif

	/* Register the partitions */
	ret = add_mtd_partitions(rtc_from4_mtd, partition_info, NUM_PARTITIONS);
	if (ret)
		goto err_3;

	/* Return happy */
	return 0;
err_3:
	nand_release(rtc_from4_mtd);
err_2:
	free_rs(rs_decoder);
err_1:
	kfree(rtc_from4_mtd);
	return ret;
}

module_init(rtc_from4_init);

/*
 * Clean up routine
 */
static void __exit rtc_from4_cleanup(void)
{
	/* Release resource, unregister partitions */
	nand_release(rtc_from4_mtd);

	/* Free the MTD device structure */
	kfree(rtc_from4_mtd);

#ifdef RTC_FROM4_HWECC
	/* Free the reed solomon resources */
	if (rs_decoder) {
		free_rs(rs_decoder);
	}
#endif
}

module_exit(rtc_from4_cleanup);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("d.marlin <dmarlin@redhat.com");
MODULE_DESCRIPTION("Board-specific glue layer for AG-AND flash on Renesas FROM_BOARD4");