1 /*
2  * Atmel AT45xxx DataFlash MTD driver for lightweight SPI framework
3  *
4  * Largely derived from at91_dataflash.c:
5  *  Copyright (C) 2003-2005 SAN People (Pty) Ltd
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * as published by the Free Software Foundation; either version
10  * 2 of the License, or (at your option) any later version.
11 */
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/delay.h>
15 #include <linux/device.h>
16 #include <linux/mutex.h>
17 #include <linux/err.h>
18 #include <linux/math64.h>
19 #include <linux/of.h>
20 #include <linux/of_device.h>
21 
22 #include <linux/spi/spi.h>
23 #include <linux/spi/flash.h>
24 
25 #include <linux/mtd/mtd.h>
26 #include <linux/mtd/partitions.h>
27 
28 /*
29  * DataFlash is a kind of SPI flash.  Most AT45 chips have two buffers in
30  * each chip, which may be used for double buffered I/O; but this driver
31  * doesn't (yet) use these for any kind of i/o overlap or prefetching.
32  *
33  * Sometimes DataFlash is packaged in MMC-format cards, although the
34  * MMC stack can't (yet?) distinguish between MMC and DataFlash
35  * protocols during enumeration.
36  */
37 
38 /* reads can bypass the buffers */
39 #define OP_READ_CONTINUOUS	0xE8
40 #define OP_READ_PAGE		0xD2
41 
42 /* group B requests can run even while status reports "busy" */
43 #define OP_READ_STATUS		0xD7	/* group B */
44 
45 /* move data between host and buffer */
46 #define OP_READ_BUFFER1		0xD4	/* group B */
47 #define OP_READ_BUFFER2		0xD6	/* group B */
48 #define OP_WRITE_BUFFER1	0x84	/* group B */
49 #define OP_WRITE_BUFFER2	0x87	/* group B */
50 
51 /* erasing flash */
52 #define OP_ERASE_PAGE		0x81
53 #define OP_ERASE_BLOCK		0x50
54 
55 /* move data between buffer and flash */
56 #define OP_TRANSFER_BUF1	0x53
57 #define OP_TRANSFER_BUF2	0x55
58 #define OP_MREAD_BUFFER1	0xD4
59 #define OP_MREAD_BUFFER2	0xD6
60 #define OP_MWERASE_BUFFER1	0x83
61 #define OP_MWERASE_BUFFER2	0x86
62 #define OP_MWRITE_BUFFER1	0x88	/* sector must be pre-erased */
63 #define OP_MWRITE_BUFFER2	0x89	/* sector must be pre-erased */
64 
65 /* write to buffer, then write-erase to flash */
66 #define OP_PROGRAM_VIA_BUF1	0x82
67 #define OP_PROGRAM_VIA_BUF2	0x85
68 
69 /* compare buffer to flash */
70 #define OP_COMPARE_BUF1		0x60
71 #define OP_COMPARE_BUF2		0x61
72 
73 /* read flash to buffer, then write-erase to flash */
74 #define OP_REWRITE_VIA_BUF1	0x58
75 #define OP_REWRITE_VIA_BUF2	0x59
76 
77 /* newer chips report JEDEC manufacturer and device IDs; chip
78  * serial number and OTP bits; and per-sector writeprotect.
79  */
80 #define OP_READ_ID		0x9F
81 #define OP_READ_SECURITY	0x77
82 #define OP_WRITE_SECURITY_REVC	0x9A
83 #define OP_WRITE_SECURITY	0x9B	/* revision D */
84 
85 #define CFI_MFR_ATMEL		0x1F
86 
87 #define DATAFLASH_SHIFT_EXTID	24
88 #define DATAFLASH_SHIFT_ID	40
89 
90 struct dataflash {
91 	u8			command[4];
92 	char			name[24];
93 
94 	unsigned short		page_offset;	/* offset in flash address */
95 	unsigned int		page_size;	/* of bytes per page */
96 
97 	struct mutex		lock;
98 	struct spi_device	*spi;
99 
100 	struct mtd_info		mtd;
101 };
102 
103 #ifdef CONFIG_OF
104 static const struct of_device_id dataflash_dt_ids[] = {
105 	{ .compatible = "atmel,at45", },
106 	{ .compatible = "atmel,dataflash", },
107 	{ /* sentinel */ }
108 };
109 MODULE_DEVICE_TABLE(of, dataflash_dt_ids);
110 #endif
111 
112 /* ......................................................................... */
113 
114 /*
115  * Return the status of the DataFlash device.
116  */
117 static inline int dataflash_status(struct spi_device *spi)
118 {
119 	/* NOTE:  at45db321c over 25 MHz wants to write
120 	 * a dummy byte after the opcode...
121 	 */
122 	return spi_w8r8(spi, OP_READ_STATUS);
123 }
124 
125 /*
126  * Poll the DataFlash device until it is READY.
127  * This usually takes 5-20 msec or so; more for sector erase.
128  */
129 static int dataflash_waitready(struct spi_device *spi)
130 {
131 	int	status;
132 
133 	for (;;) {
134 		status = dataflash_status(spi);
135 		if (status < 0) {
136 			dev_dbg(&spi->dev, "status %d?\n", status);
137 			status = 0;
138 		}
139 
140 		if (status & (1 << 7))	/* RDY/nBSY */
141 			return status;
142 
143 		msleep(3);
144 	}
145 }
146 
147 /* ......................................................................... */
148 
149 /*
150  * Erase pages of flash.
151  */
152 static int dataflash_erase(struct mtd_info *mtd, struct erase_info *instr)
153 {
154 	struct dataflash	*priv = mtd->priv;
155 	struct spi_device	*spi = priv->spi;
156 	struct spi_transfer	x = { };
157 	struct spi_message	msg;
158 	unsigned		blocksize = priv->page_size << 3;
159 	u8			*command;
160 	u32			rem;
161 
162 	dev_dbg(&spi->dev, "erase addr=0x%llx len 0x%llx\n",
163 		(long long)instr->addr, (long long)instr->len);
164 
165 	div_u64_rem(instr->len, priv->page_size, &rem);
166 	if (rem)
167 		return -EINVAL;
168 	div_u64_rem(instr->addr, priv->page_size, &rem);
169 	if (rem)
170 		return -EINVAL;
171 
172 	spi_message_init(&msg);
173 
174 	x.tx_buf = command = priv->command;
175 	x.len = 4;
176 	spi_message_add_tail(&x, &msg);
177 
178 	mutex_lock(&priv->lock);
179 	while (instr->len > 0) {
180 		unsigned int	pageaddr;
181 		int		status;
182 		int		do_block;
183 
184 		/* Calculate flash page address; use block erase (for speed) if
185 		 * we're at a block boundary and need to erase the whole block.
186 		 */
187 		pageaddr = div_u64(instr->addr, priv->page_size);
188 		do_block = (pageaddr & 0x7) == 0 && instr->len >= blocksize;
189 		pageaddr = pageaddr << priv->page_offset;
190 
191 		command[0] = do_block ? OP_ERASE_BLOCK : OP_ERASE_PAGE;
192 		command[1] = (u8)(pageaddr >> 16);
193 		command[2] = (u8)(pageaddr >> 8);
194 		command[3] = 0;
195 
196 		dev_dbg(&spi->dev, "ERASE %s: (%x) %x %x %x [%i]\n",
197 			do_block ? "block" : "page",
198 			command[0], command[1], command[2], command[3],
199 			pageaddr);
200 
201 		status = spi_sync(spi, &msg);
202 		(void) dataflash_waitready(spi);
203 
204 		if (status < 0) {
205 			dev_err(&spi->dev, "erase %x, err %d\n",
206 				pageaddr, status);
207 			/* REVISIT:  can retry instr->retries times; or
208 			 * giveup and instr->fail_addr = instr->addr;
209 			 */
210 			continue;
211 		}
212 
213 		if (do_block) {
214 			instr->addr += blocksize;
215 			instr->len -= blocksize;
216 		} else {
217 			instr->addr += priv->page_size;
218 			instr->len -= priv->page_size;
219 		}
220 	}
221 	mutex_unlock(&priv->lock);
222 
223 	/* Inform MTD subsystem that erase is complete */
224 	instr->state = MTD_ERASE_DONE;
225 	mtd_erase_callback(instr);
226 
227 	return 0;
228 }
229 
230 /*
231  * Read from the DataFlash device.
232  *   from   : Start offset in flash device
233  *   len    : Amount to read
234  *   retlen : About of data actually read
235  *   buf    : Buffer containing the data
236  */
237 static int dataflash_read(struct mtd_info *mtd, loff_t from, size_t len,
238 			       size_t *retlen, u_char *buf)
239 {
240 	struct dataflash	*priv = mtd->priv;
241 	struct spi_transfer	x[2] = { };
242 	struct spi_message	msg;
243 	unsigned int		addr;
244 	u8			*command;
245 	int			status;
246 
247 	dev_dbg(&priv->spi->dev, "read 0x%x..0x%x\n",
248 		  (unsigned int)from, (unsigned int)(from + len));
249 
250 	/* Calculate flash page/byte address */
251 	addr = (((unsigned)from / priv->page_size) << priv->page_offset)
252 		+ ((unsigned)from % priv->page_size);
253 
254 	command = priv->command;
255 
256 	dev_dbg(&priv->spi->dev, "READ: (%x) %x %x %x\n",
257 		command[0], command[1], command[2], command[3]);
258 
259 	spi_message_init(&msg);
260 
261 	x[0].tx_buf = command;
262 	x[0].len = 8;
263 	spi_message_add_tail(&x[0], &msg);
264 
265 	x[1].rx_buf = buf;
266 	x[1].len = len;
267 	spi_message_add_tail(&x[1], &msg);
268 
269 	mutex_lock(&priv->lock);
270 
271 	/* Continuous read, max clock = f(car) which may be less than
272 	 * the peak rate available.  Some chips support commands with
273 	 * fewer "don't care" bytes.  Both buffers stay unchanged.
274 	 */
275 	command[0] = OP_READ_CONTINUOUS;
276 	command[1] = (u8)(addr >> 16);
277 	command[2] = (u8)(addr >> 8);
278 	command[3] = (u8)(addr >> 0);
279 	/* plus 4 "don't care" bytes */
280 
281 	status = spi_sync(priv->spi, &msg);
282 	mutex_unlock(&priv->lock);
283 
284 	if (status >= 0) {
285 		*retlen = msg.actual_length - 8;
286 		status = 0;
287 	} else
288 		dev_dbg(&priv->spi->dev, "read %x..%x --> %d\n",
289 			(unsigned)from, (unsigned)(from + len),
290 			status);
291 	return status;
292 }
293 
294 /*
295  * Write to the DataFlash device.
296  *   to     : Start offset in flash device
297  *   len    : Amount to write
298  *   retlen : Amount of data actually written
299  *   buf    : Buffer containing the data
300  */
301 static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,
302 				size_t * retlen, const u_char * buf)
303 {
304 	struct dataflash	*priv = mtd->priv;
305 	struct spi_device	*spi = priv->spi;
306 	struct spi_transfer	x[2] = { };
307 	struct spi_message	msg;
308 	unsigned int		pageaddr, addr, offset, writelen;
309 	size_t			remaining = len;
310 	u_char			*writebuf = (u_char *) buf;
311 	int			status = -EINVAL;
312 	u8			*command;
313 
314 	dev_dbg(&spi->dev, "write 0x%x..0x%x\n",
315 		(unsigned int)to, (unsigned int)(to + len));
316 
317 	spi_message_init(&msg);
318 
319 	x[0].tx_buf = command = priv->command;
320 	x[0].len = 4;
321 	spi_message_add_tail(&x[0], &msg);
322 
323 	pageaddr = ((unsigned)to / priv->page_size);
324 	offset = ((unsigned)to % priv->page_size);
325 	if (offset + len > priv->page_size)
326 		writelen = priv->page_size - offset;
327 	else
328 		writelen = len;
329 
330 	mutex_lock(&priv->lock);
331 	while (remaining > 0) {
332 		dev_dbg(&spi->dev, "write @ %i:%i len=%i\n",
333 			pageaddr, offset, writelen);
334 
335 		/* REVISIT:
336 		 * (a) each page in a sector must be rewritten at least
337 		 *     once every 10K sibling erase/program operations.
338 		 * (b) for pages that are already erased, we could
339 		 *     use WRITE+MWRITE not PROGRAM for ~30% speedup.
340 		 * (c) WRITE to buffer could be done while waiting for
341 		 *     a previous MWRITE/MWERASE to complete ...
342 		 * (d) error handling here seems to be mostly missing.
343 		 *
344 		 * Two persistent bits per page, plus a per-sector counter,
345 		 * could support (a) and (b) ... we might consider using
346 		 * the second half of sector zero, which is just one block,
347 		 * to track that state.  (On AT91, that sector should also
348 		 * support boot-from-DataFlash.)
349 		 */
350 
351 		addr = pageaddr << priv->page_offset;
352 
353 		/* (1) Maybe transfer partial page to Buffer1 */
354 		if (writelen != priv->page_size) {
355 			command[0] = OP_TRANSFER_BUF1;
356 			command[1] = (addr & 0x00FF0000) >> 16;
357 			command[2] = (addr & 0x0000FF00) >> 8;
358 			command[3] = 0;
359 
360 			dev_dbg(&spi->dev, "TRANSFER: (%x) %x %x %x\n",
361 				command[0], command[1], command[2], command[3]);
362 
363 			status = spi_sync(spi, &msg);
364 			if (status < 0)
365 				dev_dbg(&spi->dev, "xfer %u -> %d\n",
366 					addr, status);
367 
368 			(void) dataflash_waitready(priv->spi);
369 		}
370 
371 		/* (2) Program full page via Buffer1 */
372 		addr += offset;
373 		command[0] = OP_PROGRAM_VIA_BUF1;
374 		command[1] = (addr & 0x00FF0000) >> 16;
375 		command[2] = (addr & 0x0000FF00) >> 8;
376 		command[3] = (addr & 0x000000FF);
377 
378 		dev_dbg(&spi->dev, "PROGRAM: (%x) %x %x %x\n",
379 			command[0], command[1], command[2], command[3]);
380 
381 		x[1].tx_buf = writebuf;
382 		x[1].len = writelen;
383 		spi_message_add_tail(x + 1, &msg);
384 		status = spi_sync(spi, &msg);
385 		spi_transfer_del(x + 1);
386 		if (status < 0)
387 			dev_dbg(&spi->dev, "pgm %u/%u -> %d\n",
388 				addr, writelen, status);
389 
390 		(void) dataflash_waitready(priv->spi);
391 
392 
393 #ifdef CONFIG_MTD_DATAFLASH_WRITE_VERIFY
394 
395 		/* (3) Compare to Buffer1 */
396 		addr = pageaddr << priv->page_offset;
397 		command[0] = OP_COMPARE_BUF1;
398 		command[1] = (addr & 0x00FF0000) >> 16;
399 		command[2] = (addr & 0x0000FF00) >> 8;
400 		command[3] = 0;
401 
402 		dev_dbg(&spi->dev, "COMPARE: (%x) %x %x %x\n",
403 			command[0], command[1], command[2], command[3]);
404 
405 		status = spi_sync(spi, &msg);
406 		if (status < 0)
407 			dev_dbg(&spi->dev, "compare %u -> %d\n",
408 				addr, status);
409 
410 		status = dataflash_waitready(priv->spi);
411 
412 		/* Check result of the compare operation */
413 		if (status & (1 << 6)) {
414 			dev_err(&spi->dev, "compare page %u, err %d\n",
415 				pageaddr, status);
416 			remaining = 0;
417 			status = -EIO;
418 			break;
419 		} else
420 			status = 0;
421 
422 #endif	/* CONFIG_MTD_DATAFLASH_WRITE_VERIFY */
423 
424 		remaining = remaining - writelen;
425 		pageaddr++;
426 		offset = 0;
427 		writebuf += writelen;
428 		*retlen += writelen;
429 
430 		if (remaining > priv->page_size)
431 			writelen = priv->page_size;
432 		else
433 			writelen = remaining;
434 	}
435 	mutex_unlock(&priv->lock);
436 
437 	return status;
438 }
439 
440 /* ......................................................................... */
441 
442 #ifdef CONFIG_MTD_DATAFLASH_OTP
443 
444 static int dataflash_get_otp_info(struct mtd_info *mtd, size_t len,
445 				  size_t *retlen, struct otp_info *info)
446 {
447 	/* Report both blocks as identical:  bytes 0..64, locked.
448 	 * Unless the user block changed from all-ones, we can't
449 	 * tell whether it's still writable; so we assume it isn't.
450 	 */
451 	info->start = 0;
452 	info->length = 64;
453 	info->locked = 1;
454 	*retlen = sizeof(*info);
455 	return 0;
456 }
457 
458 static ssize_t otp_read(struct spi_device *spi, unsigned base,
459 		u8 *buf, loff_t off, size_t len)
460 {
461 	struct spi_message	m;
462 	size_t			l;
463 	u8			*scratch;
464 	struct spi_transfer	t;
465 	int			status;
466 
467 	if (off > 64)
468 		return -EINVAL;
469 
470 	if ((off + len) > 64)
471 		len = 64 - off;
472 
473 	spi_message_init(&m);
474 
475 	l = 4 + base + off + len;
476 	scratch = kzalloc(l, GFP_KERNEL);
477 	if (!scratch)
478 		return -ENOMEM;
479 
480 	/* OUT: OP_READ_SECURITY, 3 don't-care bytes, zeroes
481 	 * IN:  ignore 4 bytes, data bytes 0..N (max 127)
482 	 */
483 	scratch[0] = OP_READ_SECURITY;
484 
485 	memset(&t, 0, sizeof t);
486 	t.tx_buf = scratch;
487 	t.rx_buf = scratch;
488 	t.len = l;
489 	spi_message_add_tail(&t, &m);
490 
491 	dataflash_waitready(spi);
492 
493 	status = spi_sync(spi, &m);
494 	if (status >= 0) {
495 		memcpy(buf, scratch + 4 + base + off, len);
496 		status = len;
497 	}
498 
499 	kfree(scratch);
500 	return status;
501 }
502 
503 static int dataflash_read_fact_otp(struct mtd_info *mtd,
504 		loff_t from, size_t len, size_t *retlen, u_char *buf)
505 {
506 	struct dataflash	*priv = mtd->priv;
507 	int			status;
508 
509 	/* 64 bytes, from 0..63 ... start at 64 on-chip */
510 	mutex_lock(&priv->lock);
511 	status = otp_read(priv->spi, 64, buf, from, len);
512 	mutex_unlock(&priv->lock);
513 
514 	if (status < 0)
515 		return status;
516 	*retlen = status;
517 	return 0;
518 }
519 
520 static int dataflash_read_user_otp(struct mtd_info *mtd,
521 		loff_t from, size_t len, size_t *retlen, u_char *buf)
522 {
523 	struct dataflash	*priv = mtd->priv;
524 	int			status;
525 
526 	/* 64 bytes, from 0..63 ... start at 0 on-chip */
527 	mutex_lock(&priv->lock);
528 	status = otp_read(priv->spi, 0, buf, from, len);
529 	mutex_unlock(&priv->lock);
530 
531 	if (status < 0)
532 		return status;
533 	*retlen = status;
534 	return 0;
535 }
536 
537 static int dataflash_write_user_otp(struct mtd_info *mtd,
538 		loff_t from, size_t len, size_t *retlen, u_char *buf)
539 {
540 	struct spi_message	m;
541 	const size_t		l = 4 + 64;
542 	u8			*scratch;
543 	struct spi_transfer	t;
544 	struct dataflash	*priv = mtd->priv;
545 	int			status;
546 
547 	if (from >= 64) {
548 		/*
549 		 * Attempting to write beyond the end of OTP memory,
550 		 * no data can be written.
551 		 */
552 		*retlen = 0;
553 		return 0;
554 	}
555 
556 	/* Truncate the write to fit into OTP memory. */
557 	if ((from + len) > 64)
558 		len = 64 - from;
559 
560 	/* OUT: OP_WRITE_SECURITY, 3 zeroes, 64 data-or-zero bytes
561 	 * IN:  ignore all
562 	 */
563 	scratch = kzalloc(l, GFP_KERNEL);
564 	if (!scratch)
565 		return -ENOMEM;
566 	scratch[0] = OP_WRITE_SECURITY;
567 	memcpy(scratch + 4 + from, buf, len);
568 
569 	spi_message_init(&m);
570 
571 	memset(&t, 0, sizeof t);
572 	t.tx_buf = scratch;
573 	t.len = l;
574 	spi_message_add_tail(&t, &m);
575 
576 	/* Write the OTP bits, if they've not yet been written.
577 	 * This modifies SRAM buffer1.
578 	 */
579 	mutex_lock(&priv->lock);
580 	dataflash_waitready(priv->spi);
581 	status = spi_sync(priv->spi, &m);
582 	mutex_unlock(&priv->lock);
583 
584 	kfree(scratch);
585 
586 	if (status >= 0) {
587 		status = 0;
588 		*retlen = len;
589 	}
590 	return status;
591 }
592 
593 static char *otp_setup(struct mtd_info *device, char revision)
594 {
595 	device->_get_fact_prot_info = dataflash_get_otp_info;
596 	device->_read_fact_prot_reg = dataflash_read_fact_otp;
597 	device->_get_user_prot_info = dataflash_get_otp_info;
598 	device->_read_user_prot_reg = dataflash_read_user_otp;
599 
600 	/* rev c parts (at45db321c and at45db1281 only!) use a
601 	 * different write procedure; not (yet?) implemented.
602 	 */
603 	if (revision > 'c')
604 		device->_write_user_prot_reg = dataflash_write_user_otp;
605 
606 	return ", OTP";
607 }
608 
609 #else
610 
611 static char *otp_setup(struct mtd_info *device, char revision)
612 {
613 	return " (OTP)";
614 }
615 
616 #endif
617 
618 /* ......................................................................... */
619 
620 /*
621  * Register DataFlash device with MTD subsystem.
622  */
623 static int add_dataflash_otp(struct spi_device *spi, char *name, int nr_pages,
624 			     int pagesize, int pageoffset, char revision)
625 {
626 	struct dataflash		*priv;
627 	struct mtd_info			*device;
628 	struct flash_platform_data	*pdata = dev_get_platdata(&spi->dev);
629 	char				*otp_tag = "";
630 	int				err = 0;
631 
632 	priv = kzalloc(sizeof *priv, GFP_KERNEL);
633 	if (!priv)
634 		return -ENOMEM;
635 
636 	mutex_init(&priv->lock);
637 	priv->spi = spi;
638 	priv->page_size = pagesize;
639 	priv->page_offset = pageoffset;
640 
641 	/* name must be usable with cmdlinepart */
642 	sprintf(priv->name, "spi%d.%d-%s",
643 			spi->master->bus_num, spi->chip_select,
644 			name);
645 
646 	device = &priv->mtd;
647 	device->name = (pdata && pdata->name) ? pdata->name : priv->name;
648 	device->size = nr_pages * pagesize;
649 	device->erasesize = pagesize;
650 	device->writesize = pagesize;
651 	device->type = MTD_DATAFLASH;
652 	device->flags = MTD_WRITEABLE;
653 	device->_erase = dataflash_erase;
654 	device->_read = dataflash_read;
655 	device->_write = dataflash_write;
656 	device->priv = priv;
657 
658 	device->dev.parent = &spi->dev;
659 	mtd_set_of_node(device, spi->dev.of_node);
660 
661 	if (revision >= 'c')
662 		otp_tag = otp_setup(device, revision);
663 
664 	dev_info(&spi->dev, "%s (%lld KBytes) pagesize %d bytes%s\n",
665 			name, (long long)((device->size + 1023) >> 10),
666 			pagesize, otp_tag);
667 	spi_set_drvdata(spi, priv);
668 
669 	err = mtd_device_register(device,
670 			pdata ? pdata->parts : NULL,
671 			pdata ? pdata->nr_parts : 0);
672 
673 	if (!err)
674 		return 0;
675 
676 	kfree(priv);
677 	return err;
678 }
679 
680 static inline int add_dataflash(struct spi_device *spi, char *name,
681 				int nr_pages, int pagesize, int pageoffset)
682 {
683 	return add_dataflash_otp(spi, name, nr_pages, pagesize,
684 			pageoffset, 0);
685 }
686 
687 struct flash_info {
688 	char		*name;
689 
690 	/* JEDEC id has a high byte of zero plus three data bytes:
691 	 * the manufacturer id, then a two byte device id.
692 	 */
693 	u64		jedec_id;
694 
695 	/* The size listed here is what works with OP_ERASE_PAGE. */
696 	unsigned	nr_pages;
697 	u16		pagesize;
698 	u16		pageoffset;
699 
700 	u16		flags;
701 #define SUP_EXTID	0x0004		/* supports extended ID data */
702 #define SUP_POW2PS	0x0002		/* supports 2^N byte pages */
703 #define IS_POW2PS	0x0001		/* uses 2^N byte pages */
704 };
705 
706 static struct flash_info dataflash_data[] = {
707 
708 	/*
709 	 * NOTE:  chips with SUP_POW2PS (rev D and up) need two entries,
710 	 * one with IS_POW2PS and the other without.  The entry with the
711 	 * non-2^N byte page size can't name exact chip revisions without
712 	 * losing backwards compatibility for cmdlinepart.
713 	 *
714 	 * These newer chips also support 128-byte security registers (with
715 	 * 64 bytes one-time-programmable) and software write-protection.
716 	 */
717 	{ "AT45DB011B",  0x1f2200, 512, 264, 9, SUP_POW2PS},
718 	{ "at45db011d",  0x1f2200, 512, 256, 8, SUP_POW2PS | IS_POW2PS},
719 
720 	{ "AT45DB021B",  0x1f2300, 1024, 264, 9, SUP_POW2PS},
721 	{ "at45db021d",  0x1f2300, 1024, 256, 8, SUP_POW2PS | IS_POW2PS},
722 
723 	{ "AT45DB041x",  0x1f2400, 2048, 264, 9, SUP_POW2PS},
724 	{ "at45db041d",  0x1f2400, 2048, 256, 8, SUP_POW2PS | IS_POW2PS},
725 
726 	{ "AT45DB081B",  0x1f2500, 4096, 264, 9, SUP_POW2PS},
727 	{ "at45db081d",  0x1f2500, 4096, 256, 8, SUP_POW2PS | IS_POW2PS},
728 
729 	{ "AT45DB161x",  0x1f2600, 4096, 528, 10, SUP_POW2PS},
730 	{ "at45db161d",  0x1f2600, 4096, 512, 9, SUP_POW2PS | IS_POW2PS},
731 
732 	{ "AT45DB321x",  0x1f2700, 8192, 528, 10, 0},		/* rev C */
733 
734 	{ "AT45DB321x",  0x1f2701, 8192, 528, 10, SUP_POW2PS},
735 	{ "at45db321d",  0x1f2701, 8192, 512, 9, SUP_POW2PS | IS_POW2PS},
736 
737 	{ "AT45DB642x",  0x1f2800, 8192, 1056, 11, SUP_POW2PS},
738 	{ "at45db642d",  0x1f2800, 8192, 1024, 10, SUP_POW2PS | IS_POW2PS},
739 
740 	{ "AT45DB641E",  0x1f28000100, 32768, 264, 9, SUP_EXTID | SUP_POW2PS},
741 	{ "at45db641e",  0x1f28000100, 32768, 256, 8, SUP_EXTID | SUP_POW2PS | IS_POW2PS},
742 };
743 
744 static struct flash_info *jedec_lookup(struct spi_device *spi,
745 				       u64 jedec, bool use_extid)
746 {
747 	struct flash_info *info;
748 	int status;
749 
750 	for (info = dataflash_data;
751 	     info < dataflash_data + ARRAY_SIZE(dataflash_data);
752 	     info++) {
753 		if (use_extid && !(info->flags & SUP_EXTID))
754 			continue;
755 
756 		if (info->jedec_id == jedec) {
757 			dev_dbg(&spi->dev, "OTP, sector protect%s\n",
758 				(info->flags & SUP_POW2PS) ?
759 				", binary pagesize" : "");
760 			if (info->flags & SUP_POW2PS) {
761 				status = dataflash_status(spi);
762 				if (status < 0) {
763 					dev_dbg(&spi->dev, "status error %d\n",
764 						status);
765 					return ERR_PTR(status);
766 				}
767 				if (status & 0x1) {
768 					if (info->flags & IS_POW2PS)
769 						return info;
770 				} else {
771 					if (!(info->flags & IS_POW2PS))
772 						return info;
773 				}
774 			} else
775 				return info;
776 		}
777 	}
778 
779 	return ERR_PTR(-ENODEV);
780 }
781 
782 static struct flash_info *jedec_probe(struct spi_device *spi)
783 {
784 	int ret;
785 	u8 code = OP_READ_ID;
786 	u64 jedec;
787 	u8 id[sizeof(jedec)] = {0};
788 	const unsigned int id_size = 5;
789 	struct flash_info *info;
790 
791 	/*
792 	 * JEDEC also defines an optional "extended device information"
793 	 * string for after vendor-specific data, after the three bytes
794 	 * we use here.  Supporting some chips might require using it.
795 	 *
796 	 * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
797 	 * That's not an error; only rev C and newer chips handle it, and
798 	 * only Atmel sells these chips.
799 	 */
800 	ret = spi_write_then_read(spi, &code, 1, id, id_size);
801 	if (ret < 0) {
802 		dev_dbg(&spi->dev, "error %d reading JEDEC ID\n", ret);
803 		return ERR_PTR(ret);
804 	}
805 
806 	if (id[0] != CFI_MFR_ATMEL)
807 		return NULL;
808 
809 	jedec = be64_to_cpup((__be64 *)id);
810 
811 	/*
812 	 * First, try to match device using extended device
813 	 * information
814 	 */
815 	info = jedec_lookup(spi, jedec >> DATAFLASH_SHIFT_EXTID, true);
816 	if (!IS_ERR(info))
817 		return info;
818 	/*
819 	 * If that fails, make another pass using regular ID
820 	 * information
821 	 */
822 	info = jedec_lookup(spi, jedec >> DATAFLASH_SHIFT_ID, false);
823 	if (!IS_ERR(info))
824 		return info;
825 	/*
826 	 * Treat other chips as errors ... we won't know the right page
827 	 * size (it might be binary) even when we can tell which density
828 	 * class is involved (legacy chip id scheme).
829 	 */
830 	dev_warn(&spi->dev, "JEDEC id %016llx not handled\n", jedec);
831 	return ERR_PTR(-ENODEV);
832 }
833 
834 /*
835  * Detect and initialize DataFlash device, using JEDEC IDs on newer chips
836  * or else the ID code embedded in the status bits:
837  *
838  *   Device      Density         ID code          #Pages PageSize  Offset
839  *   AT45DB011B  1Mbit   (128K)  xx0011xx (0x0c)    512    264      9
840  *   AT45DB021B  2Mbit   (256K)  xx0101xx (0x14)   1024    264      9
841  *   AT45DB041B  4Mbit   (512K)  xx0111xx (0x1c)   2048    264      9
842  *   AT45DB081B  8Mbit   (1M)    xx1001xx (0x24)   4096    264      9
843  *   AT45DB0161B 16Mbit  (2M)    xx1011xx (0x2c)   4096    528     10
844  *   AT45DB0321B 32Mbit  (4M)    xx1101xx (0x34)   8192    528     10
845  *   AT45DB0642  64Mbit  (8M)    xx111xxx (0x3c)   8192   1056     11
846  *   AT45DB1282  128Mbit (16M)   xx0100xx (0x10)  16384   1056     11
847  */
848 static int dataflash_probe(struct spi_device *spi)
849 {
850 	int status;
851 	struct flash_info	*info;
852 
853 	/*
854 	 * Try to detect dataflash by JEDEC ID.
855 	 * If it succeeds we know we have either a C or D part.
856 	 * D will support power of 2 pagesize option.
857 	 * Both support the security register, though with different
858 	 * write procedures.
859 	 */
860 	info = jedec_probe(spi);
861 	if (IS_ERR(info))
862 		return PTR_ERR(info);
863 	if (info != NULL)
864 		return add_dataflash_otp(spi, info->name, info->nr_pages,
865 				info->pagesize, info->pageoffset,
866 				(info->flags & SUP_POW2PS) ? 'd' : 'c');
867 
868 	/*
869 	 * Older chips support only legacy commands, identifing
870 	 * capacity using bits in the status byte.
871 	 */
872 	status = dataflash_status(spi);
873 	if (status <= 0 || status == 0xff) {
874 		dev_dbg(&spi->dev, "status error %d\n", status);
875 		if (status == 0 || status == 0xff)
876 			status = -ENODEV;
877 		return status;
878 	}
879 
880 	/* if there's a device there, assume it's dataflash.
881 	 * board setup should have set spi->max_speed_max to
882 	 * match f(car) for continuous reads, mode 0 or 3.
883 	 */
884 	switch (status & 0x3c) {
885 	case 0x0c:	/* 0 0 1 1 x x */
886 		status = add_dataflash(spi, "AT45DB011B", 512, 264, 9);
887 		break;
888 	case 0x14:	/* 0 1 0 1 x x */
889 		status = add_dataflash(spi, "AT45DB021B", 1024, 264, 9);
890 		break;
891 	case 0x1c:	/* 0 1 1 1 x x */
892 		status = add_dataflash(spi, "AT45DB041x", 2048, 264, 9);
893 		break;
894 	case 0x24:	/* 1 0 0 1 x x */
895 		status = add_dataflash(spi, "AT45DB081B", 4096, 264, 9);
896 		break;
897 	case 0x2c:	/* 1 0 1 1 x x */
898 		status = add_dataflash(spi, "AT45DB161x", 4096, 528, 10);
899 		break;
900 	case 0x34:	/* 1 1 0 1 x x */
901 		status = add_dataflash(spi, "AT45DB321x", 8192, 528, 10);
902 		break;
903 	case 0x38:	/* 1 1 1 x x x */
904 	case 0x3c:
905 		status = add_dataflash(spi, "AT45DB642x", 8192, 1056, 11);
906 		break;
907 	/* obsolete AT45DB1282 not (yet?) supported */
908 	default:
909 		dev_info(&spi->dev, "unsupported device (%x)\n",
910 				status & 0x3c);
911 		status = -ENODEV;
912 	}
913 
914 	if (status < 0)
915 		dev_dbg(&spi->dev, "add_dataflash --> %d\n", status);
916 
917 	return status;
918 }
919 
920 static int dataflash_remove(struct spi_device *spi)
921 {
922 	struct dataflash	*flash = spi_get_drvdata(spi);
923 	int			status;
924 
925 	dev_dbg(&spi->dev, "remove\n");
926 
927 	status = mtd_device_unregister(&flash->mtd);
928 	if (status == 0)
929 		kfree(flash);
930 	return status;
931 }
932 
933 static struct spi_driver dataflash_driver = {
934 	.driver = {
935 		.name		= "mtd_dataflash",
936 		.of_match_table = of_match_ptr(dataflash_dt_ids),
937 	},
938 
939 	.probe		= dataflash_probe,
940 	.remove		= dataflash_remove,
941 
942 	/* FIXME:  investigate suspend and resume... */
943 };
944 
945 module_spi_driver(dataflash_driver);
946 
947 MODULE_LICENSE("GPL");
948 MODULE_AUTHOR("Andrew Victor, David Brownell");
949 MODULE_DESCRIPTION("MTD DataFlash driver");
950 MODULE_ALIAS("spi:mtd_dataflash");
951