1 files changed, 228 insertions, 101 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 62e70a72aa..74c563c495 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1,6 +1,4 @@
 /*
- *  drivers/mtd/nand.c
- *
  *  Overview:
  *   This is the generic MTD driver for NAND flash devices. It should be
  *   capable of working with almost all NAND chips currently available.
@@ -45,8 +43,6 @@
 #include <asm/io.h>
 #include <asm/errno.h>
 
-static bool is_module_text_address(unsigned long addr) {return 0;}
-
 /* Define default oob placement schemes for large and small page devices */
 static struct nand_ecclayout nand_oob_8 = {
 	.eccbytes = 3,
@@ -343,13 +339,12 @@ void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
  * nand_block_bad - [DEFAULT] Read bad block marker from the chip
  * @mtd: MTD device structure
  * @ofs: offset from device start
- * @getchip: 0, if the chip is already selected
  *
  * Check, if the block is bad.
  */
-static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
+static int nand_block_bad(struct mtd_info *mtd, loff_t ofs)
 {
-	int page, chipnr, res = 0, i = 0;
+	int page, res = 0, i = 0;
 	struct nand_chip *chip = mtd_to_nand(mtd);
 	u16 bad;
 
@@ -358,15 +353,6 @@ static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
 
 	page = (int)(ofs >> chip->page_shift) & chip->pagemask;
 
-	if (getchip) {
-		chipnr = (int)(ofs >> chip->chip_shift);
-
-		nand_get_device(mtd, FL_READING);
-
-		/* Select the NAND device */
-		chip->select_chip(mtd, chipnr);
-	}
-
 	do {
 		if (chip->options & NAND_BUSWIDTH_16) {
 			chip->cmdfunc(mtd, NAND_CMD_READOOB,
@@ -391,11 +377,6 @@ static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
 		i++;
 	} while (!res && i < 2 && (chip->bbt_options & NAND_BBT_SCAN2NDPAGE));
 
-	if (getchip) {
-		chip->select_chip(mtd, -1);
-		nand_release_device(mtd);
-	}
-
 	return res;
 }
 
@@ -533,14 +514,12 @@ static int nand_block_isreserved(struct mtd_info *mtd, loff_t ofs)
  * nand_block_checkbad - [GENERIC] Check if a block is marked bad
  * @mtd: MTD device structure
  * @ofs: offset from device start
- * @getchip: 0, if the chip is already selected
  * @allowbbt: 1, if its allowed to access the bbt area
  *
  * Check, if the block is bad. Either by reading the bad block table or
  * calling of the scan function.
  */
-static int nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip,
-			       int allowbbt)
+static int nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int allowbbt)
 {
 	struct nand_chip *chip = mtd_to_nand(mtd);
 
@@ -551,17 +530,22 @@ static int nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip,
 	}
 
 	if (!chip->bbt)
-		return chip->block_bad(mtd, ofs, getchip);
+		return chip->block_bad(mtd, ofs);
 
 	/* Return info from the table */
 	return nand_isbad_bbt(mtd, ofs, allowbbt);
 }
 
-/* Wait for the ready pin, after a command. The timeout is caught later. */
+/**
+ * nand_wait_ready - [GENERIC] Wait for the ready pin after commands.
+ * @mtd: MTD device structure
+ *
+ * Wait for the ready pin after a command, and warn if a timeout occurs.
+ */
 void nand_wait_ready(struct mtd_info *mtd)
 {
 	struct nand_chip *chip = mtd_to_nand(mtd);
-	u32 timeo = (CONFIG_SYS_HZ * 20) / 1000;
+	u32 timeo = (CONFIG_SYS_HZ * 400) / 1000;
 	u32 time_start;
 
 	time_start = get_timer(0);
@@ -571,6 +555,9 @@ void nand_wait_ready(struct mtd_info *mtd)
 			if (chip->dev_ready(mtd))
 				break;
 	}
+
+	if (!chip->dev_ready(mtd))
+		pr_warn("timeout while waiting for chip to become ready\n");
 }
 EXPORT_SYMBOL_GPL(nand_wait_ready);
 
@@ -871,15 +858,13 @@ static void panic_nand_wait(struct mtd_info *mtd, struct nand_chip *chip,
  * @mtd: MTD device structure
  * @chip: NAND chip structure
  *
- * Wait for command done. This applies to erase and program only. Erase can
- * take up to 400ms and program up to 20ms according to general NAND and
- * SmartMedia specs.
+ * Wait for command done. This applies to erase and program only.
  */
 static int nand_wait(struct mtd_info *mtd, struct nand_chip *chip)
 {
 
-	int status, state = chip->state;
-	unsigned long timeo = (state == FL_ERASING ? 400 : 20);
+	int status;
+	unsigned long timeo = 400;
 
 	led_trigger_event(nand_led_trigger, LED_FULL);
 
@@ -912,6 +897,135 @@ static int nand_wait(struct mtd_info *mtd, struct nand_chip *chip)
 	return status;
 }
 
+#define BITS_PER_BYTE 8
+
+/**
+ * nand_check_erased_buf - check if a buffer contains (almost) only 0xff data
+ * @buf: buffer to test
+ * @len: buffer length
+ * @bitflips_threshold: maximum number of bitflips
+ *
+ * Check if a buffer contains only 0xff, which means the underlying region
+ * has been erased and is ready to be programmed.
+ * The bitflips_threshold specify the maximum number of bitflips before
+ * considering the region is not erased.
+ * Note: The logic of this function has been extracted from the memweight
+ * implementation, except that nand_check_erased_buf function exit before
+ * testing the whole buffer if the number of bitflips exceed the
+ * bitflips_threshold value.
+ *
+ * Returns a positive number of bitflips less than or equal to
+ * bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
+ * threshold.
+ */
+static int nand_check_erased_buf(void *buf, int len, int bitflips_threshold)
+{
+	const unsigned char *bitmap = buf;
+	int bitflips = 0;
+	int weight;
+
+	for (; len && ((uintptr_t)bitmap) % sizeof(long);
+	     len--, bitmap++) {
+		weight = hweight8(*bitmap);
+		bitflips += BITS_PER_BYTE - weight;
+		if (unlikely(bitflips > bitflips_threshold))
+			return -EBADMSG;
+	}
+
+	for (; len >= 4; len -= 4, bitmap += 4) {
+		weight = hweight32(*((u32 *)bitmap));
+		bitflips += 32 - weight;
+		if (unlikely(bitflips > bitflips_threshold))
+			return -EBADMSG;
+	}
+
+	for (; len > 0; len--, bitmap++) {
+		weight = hweight8(*bitmap);
+		bitflips += BITS_PER_BYTE - weight;
+		if (unlikely(bitflips > bitflips_threshold))
+			return -EBADMSG;
+	}
+
+	return bitflips;
+}
+
+/**
+ * nand_check_erased_ecc_chunk - check if an ECC chunk contains (almost) only
+ *				 0xff data
+ * @data: data buffer to test
+ * @datalen: data length
+ * @ecc: ECC buffer
+ * @ecclen: ECC length
+ * @extraoob: extra OOB buffer
+ * @extraooblen: extra OOB length
+ * @bitflips_threshold: maximum number of bitflips
+ *
+ * Check if a data buffer and its associated ECC and OOB data contains only
+ * 0xff pattern, which means the underlying region has been erased and is
+ * ready to be programmed.
+ * The bitflips_threshold specify the maximum number of bitflips before
+ * considering the region as not erased.
+ *
+ * Note:
+ * 1/ ECC algorithms are working on pre-defined block sizes which are usually
+ *    different from the NAND page size. When fixing bitflips, ECC engines will
+ *    report the number of errors per chunk, and the NAND core infrastructure
+ *    expect you to return the maximum number of bitflips for the whole page.
+ *    This is why you should always use this function on a single chunk and
+ *    not on the whole page. After checking each chunk you should update your
+ *    max_bitflips value accordingly.
+ * 2/ When checking for bitflips in erased pages you should not only check
+ *    the payload data but also their associated ECC data, because a user might
+ *    have programmed almost all bits to 1 but a few. In this case, we
+ *    shouldn't consider the chunk as erased, and checking ECC bytes prevent
+ *    this case.
+ * 3/ The extraoob argument is optional, and should be used if some of your OOB
+ *    data are protected by the ECC engine.
+ *    It could also be used if you support subpages and want to attach some
+ *    extra OOB data to an ECC chunk.
+ *
+ * Returns a positive number of bitflips less than or equal to
+ * bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
+ * threshold. In case of success, the passed buffers are filled with 0xff.
+ */
+int nand_check_erased_ecc_chunk(void *data, int datalen,
+				void *ecc, int ecclen,
+				void *extraoob, int extraooblen,
+				int bitflips_threshold)
+{
+	int data_bitflips = 0, ecc_bitflips = 0, extraoob_bitflips = 0;
+
+	data_bitflips = nand_check_erased_buf(data, datalen,
+					      bitflips_threshold);
+	if (data_bitflips < 0)
+		return data_bitflips;
+
+	bitflips_threshold -= data_bitflips;
+
+	ecc_bitflips = nand_check_erased_buf(ecc, ecclen, bitflips_threshold);
+	if (ecc_bitflips < 0)
+		return ecc_bitflips;
+
+	bitflips_threshold -= ecc_bitflips;
+
+	extraoob_bitflips = nand_check_erased_buf(extraoob, extraooblen,
+						  bitflips_threshold);
+	if (extraoob_bitflips < 0)
+		return extraoob_bitflips;
+
+	if (data_bitflips)
+		memset(data, 0xff, datalen);
+
+	if (ecc_bitflips)
+		memset(ecc, 0xff, ecclen);
+
+	if (extraoob_bitflips)
+		memset(extraoob, 0xff, extraooblen);
+
+	return data_bitflips + ecc_bitflips + extraoob_bitflips;
+}
+EXPORT_SYMBOL(nand_check_erased_ecc_chunk);
+
 /**
  * nand_read_page_raw - [INTERN] read raw page data without ecc
  * @mtd: mtd info structure
@@ -1103,6 +1217,16 @@ static int nand_read_subpage(struct mtd_info *mtd, struct nand_chip *chip,
 
 		stat = chip->ecc.correct(mtd, p,
 			&chip->buffers->ecccode[i], &chip->buffers->ecccalc[i]);
+		if (stat == -EBADMSG &&
+		    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
+			/* check for empty pages with bitflips */
+			stat = nand_check_erased_ecc_chunk(p, chip->ecc.size,
+						&chip->buffers->ecccode[i],
+						chip->ecc.bytes,
+						NULL, 0,
+						chip->ecc.strength);
+		}
+
 		if (stat < 0) {
 			mtd->ecc_stats.failed++;
 		} else {
@@ -1152,6 +1276,15 @@ static int nand_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
 		int stat;
 
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
+		if (stat == -EBADMSG &&
+		    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
+			/* check for empty pages with bitflips */
+			stat = nand_check_erased_ecc_chunk(p, eccsize,
+						&ecc_code[i], eccbytes,
+						NULL, 0,
+						chip->ecc.strength);
+		}
+
 		if (stat < 0) {
 			mtd->ecc_stats.failed++;
 		} else {
@@ -1204,6 +1337,15 @@ static int nand_read_page_hwecc_oob_first(struct mtd_info *mtd,
 		chip->ecc.calculate(mtd, p, &ecc_calc[i]);
 
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], NULL);
+		if (stat == -EBADMSG &&
+		    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
+			/* check for empty pages with bitflips */
+			stat = nand_check_erased_ecc_chunk(p, eccsize,
+						&ecc_code[i], eccbytes,
+						NULL, 0,
+						chip->ecc.strength);
+		}
+
 		if (stat < 0) {
 			mtd->ecc_stats.failed++;
 		} else {
@@ -1231,6 +1373,7 @@ static int nand_read_page_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
 	int i, eccsize = chip->ecc.size;
 	int eccbytes = chip->ecc.bytes;
 	int eccsteps = chip->ecc.steps;
+	int eccpadbytes = eccbytes + chip->ecc.prepad + chip->ecc.postpad;
 	uint8_t *p = buf;
 	uint8_t *oob = chip->oob_poi;
 	unsigned int max_bitflips = 0;
@@ -1250,19 +1393,29 @@ static int nand_read_page_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
 		chip->read_buf(mtd, oob, eccbytes);
 		stat = chip->ecc.correct(mtd, p, oob, NULL);
 
-		if (stat < 0) {
-			mtd->ecc_stats.failed++;
-		} else {
-			mtd->ecc_stats.corrected += stat;
-			max_bitflips = max_t(unsigned int, max_bitflips, stat);
-		}
-
 		oob += eccbytes;
 
 		if (chip->ecc.postpad) {
 			chip->read_buf(mtd, oob, chip->ecc.postpad);
 			oob += chip->ecc.postpad;
 		}
+
+		if (stat == -EBADMSG &&
+		    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
+			/* check for empty pages with bitflips */
+			stat = nand_check_erased_ecc_chunk(p, chip->ecc.size,
+							   oob - eccpadbytes,
+							   eccpadbytes,
+							   NULL, 0,
+							   chip->ecc.strength);
+		}
+
+		if (stat < 0) {
+			mtd->ecc_stats.failed++;
+		} else {
+			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 	}
 
 	/* Calculate remaining oob bytes */
@@ -1361,8 +1514,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 	int ret = 0;
 	uint32_t readlen = ops->len;
 	uint32_t oobreadlen = ops->ooblen;
-	uint32_t max_oobsize = ops->mode == MTD_OPS_AUTO_OOB ?
-		mtd->oobavail : mtd->oobsize;
+	uint32_t max_oobsize = mtd_oobavail(mtd, ops);
 
 	uint8_t *bufpoi, *oob, *buf;
 	int use_bufpoi;
@@ -1712,10 +1864,7 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
 
 	stats = mtd->ecc_stats;
 
-	if (ops->mode == MTD_OPS_AUTO_OOB)
-		len = chip->ecc.layout->oobavail;
-	else
-		len = mtd->oobsize;
+	len = mtd_oobavail(mtd, ops);
 
 	if (unlikely(ops->ooboffs >= len)) {
 		pr_debug("%s: attempt to start read outside oob\n",
@@ -1845,8 +1994,7 @@ out:
  * Not for syndrome calculating ECC controllers, which use a special oob layout.
  */
 static int nand_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
-				const uint8_t *buf, int oob_required,
-				int page)
+			       const uint8_t *buf, int oob_required, int page)
 {
 	chip->write_buf(mtd, buf, mtd->writesize);
 	if (oob_required)
@@ -1861,6 +2009,7 @@ static int nand_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
  * @chip: nand chip info structure
  * @buf: data buffer
  * @oob_required: must write chip->oob_poi to OOB
+ * @page: page number to write
  *
  * We need a special oob layout and handling even when ECC isn't checked.
  */
@@ -1907,8 +2056,8 @@ static int nand_write_page_raw_syndrome(struct mtd_info *mtd,
  * @page: page number to write
  */
 static int nand_write_page_swecc(struct mtd_info *mtd, struct nand_chip *chip,
-				  const uint8_t *buf, int oob_required,
-				  int page)
+				 const uint8_t *buf, int oob_required,
+				 int page)
 {
 	int i, eccsize = chip->ecc.size;
 	int eccbytes = chip->ecc.bytes;
@@ -2029,6 +2178,7 @@ static int nand_write_subpage_hwecc(struct mtd_info *mtd,
  * @chip: nand chip info structure
  * @buf: data buffer
  * @oob_required: must write chip->oob_poi to OOB
+ * @page: page number to write
  *
  * The hw generator calculates the error syndrome automatically. Therefore we
  * need a special oob layout and handling.
@@ -2103,7 +2253,7 @@ static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
 						  oob_required, page);
 	else if (subpage)
 		status = chip->ecc.write_subpage(mtd, chip, offset, data_len,
-						  buf, oob_required, page);
+						 buf, oob_required, page);
 	else
 		status = chip->ecc.write_page(mtd, chip, buf, oob_required,
 					      page);
@@ -2145,7 +2295,6 @@ static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
  * @oob: oob data buffer
  * @len: oob data write length
  * @ops: oob ops structure
- * @page: page number to write
  */
 static uint8_t *nand_fill_oob(struct mtd_info *mtd, uint8_t *oob, size_t len,
 			      struct mtd_oob_ops *ops)
@@ -2214,8 +2363,7 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
 	uint32_t writelen = ops->len;
 
 	uint32_t oobwritelen = ops->ooblen;
-	uint32_t oobmaxlen = ops->mode == MTD_OPS_AUTO_OOB ?
-				mtd->oobavail : mtd->oobsize;
+	uint32_t oobmaxlen = mtd_oobavail(mtd, ops);
 
 	uint8_t *oob = ops->oobbuf;
 	uint8_t *buf = ops->datbuf;
@@ -2404,10 +2552,7 @@ static int nand_do_write_oob(struct mtd_info *mtd, loff_t to,
 	pr_debug("%s: to = 0x%08x, len = %i\n",
 			 __func__, (unsigned int)to, (int)ops->ooblen);
 
-	if (ops->mode == MTD_OPS_AUTO_OOB)
-		len = chip->ecc.layout->oobavail;
-	else
-		len = mtd->oobsize;
+	len = mtd_oobavail(mtd, ops);
 
 	/* Do not allow write past end of page */
 	if ((ops->ooboffs + ops->ooblen) > len) {
@@ -2597,7 +2742,7 @@ int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
 
 		/* Check if we have a bad block, we do not erase bad blocks! */
 		if (!instr->scrub && nand_block_checkbad(mtd, ((loff_t) page) <<
-					chip->page_shift, 0, allowbbt)) {
+					chip->page_shift, allowbbt)) {
 			pr_warn("%s: attempt to erase a bad block at page 0x%08x\n",
 				    __func__, page);
 			instr->state = MTD_ERASE_FAILED;
@@ -2684,7 +2829,20 @@ static void nand_sync(struct mtd_info *mtd)
  */
 static int nand_block_isbad(struct mtd_info *mtd, loff_t offs)
 {
-	return nand_block_checkbad(mtd, offs, 1, 0);
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	int chipnr = (int)(offs >> chip->chip_shift);
+	int ret;
+
+	/* Select the NAND device */
+	nand_get_device(mtd, FL_READING);
+	chip->select_chip(mtd, chipnr);
+
+	ret = nand_block_checkbad(mtd, offs, 0);
+
+	chip->select_chip(mtd, -1);
+	nand_release_device(mtd);
+
+	return ret;
 }
 
 /**
@@ -2756,9 +2914,6 @@ static int nand_onfi_get_features(struct mtd_info *mtd, struct nand_chip *chip,
 		return -EINVAL;
 #endif
 
-	/* clear the sub feature parameters */
-	memset(subfeature_param, 0, ONFI_SUBFEATURE_PARAM_LEN);
-
 	chip->cmdfunc(mtd, NAND_CMD_GET_FEATURES, addr, -1);
 	for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i)
 		*subfeature_param++ = chip->read_byte(mtd);
@@ -3491,7 +3646,7 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
 			if (find_full_id_nand(mtd, chip, type, id_data, &busw))
 				goto ident_done;
 		} else if (*dev_id == type->dev_id) {
-				break;
+			break;
 		}
 	}
 
@@ -3514,10 +3669,7 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
 
 	chip->chipsize = (uint64_t)type->chipsize << 20;
 
-	if (!type->pagesize && chip->init_size) {
-		/* Set the pagesize, oobsize, erasesize by the driver */
-		busw = chip->init_size(mtd, chip, id_data);
-	} else if (!type->pagesize) {
+	if (!type->pagesize) {
 		/* Decode parameters from extended ID */
 		nand_decode_ext_id(mtd, chip, id_data, &busw);
 	} else {
@@ -3621,7 +3773,6 @@ ident_done:
  * This is the first phase of the normal nand_scan() function. It reads the
  * flash ID and sets up MTD fields accordingly.
  *
- * The mtd->owner field must be set to the module of the caller.
  */
 int nand_scan_ident(struct mtd_info *mtd, int maxchips,
 		    struct nand_flash_dev *table)
@@ -3797,7 +3948,7 @@ int nand_scan_tail(struct mtd_info *mtd)
 			ecc->write_oob = nand_write_oob_std;
 		if (!ecc->read_subpage)
 			ecc->read_subpage = nand_read_subpage;
-		if (!ecc->write_subpage)
+		if (!ecc->write_subpage && ecc->hwctl && ecc->calculate)
 			ecc->write_subpage = nand_write_subpage_hwecc;
 
 	case NAND_ECC_HW_SYNDROME:
@@ -3875,10 +4026,8 @@ int nand_scan_tail(struct mtd_info *mtd)
 		}
 
 		/* See nand_bch_init() for details. */
-		ecc->bytes = DIV_ROUND_UP(
-				ecc->strength * fls(8 * ecc->size), 8);
-		ecc->priv = nand_bch_init(mtd, ecc->size, ecc->bytes,
-					       &ecc->layout);
+		ecc->bytes = 0;
+		ecc->priv = nand_bch_init(mtd);
 		if (!ecc->priv) {
 			pr_warn("BCH ECC initialization failed!\n");
 			BUG();
@@ -3913,11 +4062,11 @@ int nand_scan_tail(struct mtd_info *mtd)
 	 * The number of bytes available for a client to place data into
 	 * the out of band area.
 	 */
-	ecc->layout->oobavail = 0;
-	for (i = 0; ecc->layout->oobfree[i].length
-			&& i < ARRAY_SIZE(ecc->layout->oobfree); i++)
-		ecc->layout->oobavail += ecc->layout->oobfree[i].length;
-	mtd->oobavail = ecc->layout->oobavail;
+	mtd->oobavail = 0;
+	if (ecc->layout) {
+		for (i = 0; ecc->layout->oobfree[i].length; i++)
+			mtd->oobavail += ecc->layout->oobfree[i].length;
+	}
 
 	/* ECC sanity check: warn if it's too weak */
 	if (!nand_ecc_strength_good(mtd))
@@ -4002,18 +4151,6 @@ int nand_scan_tail(struct mtd_info *mtd)
 }
 EXPORT_SYMBOL(nand_scan_tail);
 
-/*
- * is_module_text_address() isn't exported, and it's mostly a pointless
- * test if this is a module _anyway_ -- they'd have to try _really_ hard
- * to call us from in-kernel code if the core NAND support is modular.
- */
-#ifdef MODULE
-#define caller_is_module() (1)
-#else
-#define caller_is_module() \
-	is_module_text_address((unsigned long)__builtin_return_address(0))
-#endif
-
 /**
  * nand_scan - [NAND Interface] Scan for the NAND device
  * @mtd: MTD device structure
@@ -4021,19 +4158,12 @@ EXPORT_SYMBOL(nand_scan_tail);
  *
  * This fills out all the uninitialized function pointers with the defaults.
  * The flash ID is read and the mtd/chip structures are filled with the
- * appropriate values. The mtd->owner field must be set to the module of the
- * caller.
+ * appropriate values.
  */
 int nand_scan(struct mtd_info *mtd, int maxchips)
 {
 	int ret;
 
-	/* Many callers got this wrong, so check for it for a while... */
-	if (!mtd->owner && caller_is_module()) {
-		pr_crit("%s called with NULL mtd->owner!\n", __func__);
-		BUG();
-	}
-
 	ret = nand_scan_ident(mtd, maxchips, NULL);
 	if (!ret)
 		ret = nand_scan_tail(mtd);
@@ -4041,9 +4171,6 @@ int nand_scan(struct mtd_info *mtd, int maxchips)
 }
 EXPORT_SYMBOL(nand_scan);
 
-module_init(nand_base_init);
-module_exit(nand_base_exit);
-
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Steven J. Hill <sjhill@realitydiluted.com>");
 MODULE_AUTHOR("Thomas Gleixner <tglx@linutronix.de>");