Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 897 insertions, 0 deletions

diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
new file mode 100644
index 00000000000..8f66d093c80
--- /dev/null
+++ b/drivers/mtd/mtdconcat.c
@@ -0,0 +1,897 @@
+/*
+ * MTD device concatenation layer
+ *
+ * (C) 2002 Robert Kaiser <rkaiser@sysgo.de>
+ *
+ * NAND support by Christian Gan <cgan@iders.ca>
+ *
+ * This code is GPL
+ *
+ * $Id: mtdconcat.c,v 1.9 2004/06/30 15:17:41 dbrown Exp $
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/concat.h>
+
+/*
+ * Our storage structure:
+ * Subdev points to an array of pointers to struct mtd_info objects
+ * which is allocated along with this structure
+ *
+ */
+struct mtd_concat {
+	struct mtd_info mtd;
+	int num_subdev;
+	struct mtd_info **subdev;
+};
+
+/*
+ * how to calculate the size required for the above structure,
+ * including the pointer array subdev points to:
+ */
+#define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)	\
+	((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
+
+/*
+ * Given a pointer to the MTD object in the mtd_concat structure,
+ * we can retrieve the pointer to that structure with this macro.
+ */
+#define CONCAT(x)  ((struct mtd_concat *)(x))
+
+/* 
+ * MTD methods which look up the relevant subdevice, translate the
+ * effective address and pass through to the subdevice.
+ */
+
+static int
+concat_read(struct mtd_info *mtd, loff_t from, size_t len,
+	    size_t * retlen, u_char * buf)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int err = -EINVAL;
+	int i;
+
+	*retlen = 0;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size, retsize;
+
+		if (from >= subdev->size) {
+			/* Not destined for this subdev */
+			size = 0;
+			from -= subdev->size;
+			continue;
+		}
+		if (from + len > subdev->size)
+			/* First part goes into this subdev */
+			size = subdev->size - from;
+		else
+			/* Entire transaction goes into this subdev */
+			size = len;
+
+		err = subdev->read(subdev, from, size, &retsize, buf);
+
+		if (err)
+			break;
+
+		*retlen += retsize;
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		buf += size;
+		from = 0;
+	}
+	return err;
+}
+
+static int
+concat_write(struct mtd_info *mtd, loff_t to, size_t len,
+	     size_t * retlen, const u_char * buf)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int err = -EINVAL;
+	int i;
+
+	if (!(mtd->flags & MTD_WRITEABLE))
+		return -EROFS;
+
+	*retlen = 0;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size, retsize;
+
+		if (to >= subdev->size) {
+			size = 0;
+			to -= subdev->size;
+			continue;
+		}
+		if (to + len > subdev->size)
+			size = subdev->size - to;
+		else
+			size = len;
+
+		if (!(subdev->flags & MTD_WRITEABLE))
+			err = -EROFS;
+		else
+			err = subdev->write(subdev, to, size, &retsize, buf);
+
+		if (err)
+			break;
+
+		*retlen += retsize;
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		buf += size;
+		to = 0;
+	}
+	return err;
+}
+
+static int
+concat_read_ecc(struct mtd_info *mtd, loff_t from, size_t len,
+		size_t * retlen, u_char * buf, u_char * eccbuf,
+		struct nand_oobinfo *oobsel)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int err = -EINVAL;
+	int i;
+
+	*retlen = 0;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size, retsize;
+
+		if (from >= subdev->size) {
+			/* Not destined for this subdev */
+			size = 0;
+			from -= subdev->size;
+			continue;
+		}
+
+		if (from + len > subdev->size)
+			/* First part goes into this subdev */
+			size = subdev->size - from;
+		else
+			/* Entire transaction goes into this subdev */
+			size = len;
+
+		if (subdev->read_ecc)
+			err = subdev->read_ecc(subdev, from, size,
+					       &retsize, buf, eccbuf, oobsel);
+		else
+			err = -EINVAL;
+
+		if (err)
+			break;
+
+		*retlen += retsize;
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		buf += size;
+		if (eccbuf) {
+			eccbuf += subdev->oobsize;
+			/* in nand.c at least, eccbufs are
+			   tagged with 2 (int)eccstatus'; we
+			   must account for these */
+			eccbuf += 2 * (sizeof (int));
+		}
+		from = 0;
+	}
+	return err;
+}
+
+static int
+concat_write_ecc(struct mtd_info *mtd, loff_t to, size_t len,
+		 size_t * retlen, const u_char * buf, u_char * eccbuf,
+		 struct nand_oobinfo *oobsel)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int err = -EINVAL;
+	int i;
+
+	if (!(mtd->flags & MTD_WRITEABLE))
+		return -EROFS;
+
+	*retlen = 0;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size, retsize;
+
+		if (to >= subdev->size) {
+			size = 0;
+			to -= subdev->size;
+			continue;
+		}
+		if (to + len > subdev->size)
+			size = subdev->size - to;
+		else
+			size = len;
+
+		if (!(subdev->flags & MTD_WRITEABLE))
+			err = -EROFS;
+		else if (subdev->write_ecc)
+			err = subdev->write_ecc(subdev, to, size,
+						&retsize, buf, eccbuf, oobsel);
+		else
+			err = -EINVAL;
+
+		if (err)
+			break;
+
+		*retlen += retsize;
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		buf += size;
+		if (eccbuf)
+			eccbuf += subdev->oobsize;
+		to = 0;
+	}
+	return err;
+}
+
+static int
+concat_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
+		size_t * retlen, u_char * buf)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int err = -EINVAL;
+	int i;
+
+	*retlen = 0;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size, retsize;
+
+		if (from >= subdev->size) {
+			/* Not destined for this subdev */
+			size = 0;
+			from -= subdev->size;
+			continue;
+		}
+		if (from + len > subdev->size)
+			/* First part goes into this subdev */
+			size = subdev->size - from;
+		else
+			/* Entire transaction goes into this subdev */
+			size = len;
+
+		if (subdev->read_oob)
+			err = subdev->read_oob(subdev, from, size,
+					       &retsize, buf);
+		else
+			err = -EINVAL;
+
+		if (err)
+			break;
+
+		*retlen += retsize;
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		buf += size;
+		from = 0;
+	}
+	return err;
+}
+
+static int
+concat_write_oob(struct mtd_info *mtd, loff_t to, size_t len,
+		 size_t * retlen, const u_char * buf)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int err = -EINVAL;
+	int i;
+
+	if (!(mtd->flags & MTD_WRITEABLE))
+		return -EROFS;
+
+	*retlen = 0;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size, retsize;
+
+		if (to >= subdev->size) {
+			size = 0;
+			to -= subdev->size;
+			continue;
+		}
+		if (to + len > subdev->size)
+			size = subdev->size - to;
+		else
+			size = len;
+
+		if (!(subdev->flags & MTD_WRITEABLE))
+			err = -EROFS;
+		else if (subdev->write_oob)
+			err = subdev->write_oob(subdev, to, size, &retsize,
+						buf);
+		else
+			err = -EINVAL;
+
+		if (err)
+			break;
+
+		*retlen += retsize;
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		buf += size;
+		to = 0;
+	}
+	return err;
+}
+
+static void concat_erase_callback(struct erase_info *instr)
+{
+	wake_up((wait_queue_head_t *) instr->priv);
+}
+
+static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
+{
+	int err;
+	wait_queue_head_t waitq;
+	DECLARE_WAITQUEUE(wait, current);
+
+	/*
+	 * This code was stol^H^H^H^Hinspired by mtdchar.c
+	 */
+	init_waitqueue_head(&waitq);
+
+	erase->mtd = mtd;
+	erase->callback = concat_erase_callback;
+	erase->priv = (unsigned long) &waitq;
+
+	/*
+	 * FIXME: Allow INTERRUPTIBLE. Which means
+	 * not having the wait_queue head on the stack.
+	 */
+	err = mtd->erase(mtd, erase);
+	if (!err) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		add_wait_queue(&waitq, &wait);
+		if (erase->state != MTD_ERASE_DONE
+		    && erase->state != MTD_ERASE_FAILED)
+			schedule();
+		remove_wait_queue(&waitq, &wait);
+		set_current_state(TASK_RUNNING);
+
+		err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
+	}
+	return err;
+}
+
+static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	struct mtd_info *subdev;
+	int i, err;
+	u_int32_t length, offset = 0;
+	struct erase_info *erase;
+
+	if (!(mtd->flags & MTD_WRITEABLE))
+		return -EROFS;
+
+	if (instr->addr > concat->mtd.size)
+		return -EINVAL;
+
+	if (instr->len + instr->addr > concat->mtd.size)
+		return -EINVAL;
+
+	/*
+	 * Check for proper erase block alignment of the to-be-erased area.
+	 * It is easier to do this based on the super device's erase
+	 * region info rather than looking at each particular sub-device
+	 * in turn.
+	 */
+	if (!concat->mtd.numeraseregions) {
+		/* the easy case: device has uniform erase block size */
+		if (instr->addr & (concat->mtd.erasesize - 1))
+			return -EINVAL;
+		if (instr->len & (concat->mtd.erasesize - 1))
+			return -EINVAL;
+	} else {
+		/* device has variable erase size */
+		struct mtd_erase_region_info *erase_regions =
+		    concat->mtd.eraseregions;
+
+		/*
+		 * Find the erase region where the to-be-erased area begins:
+		 */
+		for (i = 0; i < concat->mtd.numeraseregions &&
+		     instr->addr >= erase_regions[i].offset; i++) ;
+		--i;
+
+		/*
+		 * Now erase_regions[i] is the region in which the
+		 * to-be-erased area begins. Verify that the starting
+		 * offset is aligned to this region's erase size:
+		 */
+		if (instr->addr & (erase_regions[i].erasesize - 1))
+			return -EINVAL;
+
+		/*
+		 * now find the erase region where the to-be-erased area ends:
+		 */
+		for (; i < concat->mtd.numeraseregions &&
+		     (instr->addr + instr->len) >= erase_regions[i].offset;
+		     ++i) ;
+		--i;
+		/*
+		 * check if the ending offset is aligned to this region's erase size
+		 */
+		if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
+						  1))
+			return -EINVAL;
+	}
+
+	instr->fail_addr = 0xffffffff;
+
+	/* make a local copy of instr to avoid modifying the caller's struct */
+	erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
+
+	if (!erase)
+		return -ENOMEM;
+
+	*erase = *instr;
+	length = instr->len;
+
+	/*
+	 * find the subdevice where the to-be-erased area begins, adjust
+	 * starting offset to be relative to the subdevice start
+	 */
+	for (i = 0; i < concat->num_subdev; i++) {
+		subdev = concat->subdev[i];
+		if (subdev->size <= erase->addr) {
+			erase->addr -= subdev->size;
+			offset += subdev->size;
+		} else {
+			break;
+		}
+	}
+
+	/* must never happen since size limit has been verified above */
+	if (i >= concat->num_subdev)
+		BUG();
+
+	/* now do the erase: */
+	err = 0;
+	for (; length > 0; i++) {
+		/* loop for all subdevices affected by this request */
+		subdev = concat->subdev[i];	/* get current subdevice */
+
+		/* limit length to subdevice's size: */
+		if (erase->addr + length > subdev->size)
+			erase->len = subdev->size - erase->addr;
+		else
+			erase->len = length;
+
+		if (!(subdev->flags & MTD_WRITEABLE)) {
+			err = -EROFS;
+			break;
+		}
+		length -= erase->len;
+		if ((err = concat_dev_erase(subdev, erase))) {
+			/* sanity check: should never happen since
+			 * block alignment has been checked above */
+			if (err == -EINVAL)
+				BUG();
+			if (erase->fail_addr != 0xffffffff)
+				instr->fail_addr = erase->fail_addr + offset;
+			break;
+		}
+		/*
+		 * erase->addr specifies the offset of the area to be
+		 * erased *within the current subdevice*. It can be
+		 * non-zero only the first time through this loop, i.e.
+		 * for the first subdevice where blocks need to be erased.
+		 * All the following erases must begin at the start of the
+		 * current subdevice, i.e. at offset zero.
+		 */
+		erase->addr = 0;
+		offset += subdev->size;
+	}
+	instr->state = erase->state;
+	kfree(erase);
+	if (err)
+		return err;
+
+	if (instr->callback)
+		instr->callback(instr);
+	return 0;
+}
+
+static int concat_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int i, err = -EINVAL;
+
+	if ((len + ofs) > mtd->size)
+		return -EINVAL;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size;
+
+		if (ofs >= subdev->size) {
+			size = 0;
+			ofs -= subdev->size;
+			continue;
+		}
+		if (ofs + len > subdev->size)
+			size = subdev->size - ofs;
+		else
+			size = len;
+
+		err = subdev->lock(subdev, ofs, size);
+
+		if (err)
+			break;
+
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		ofs = 0;
+	}
+
+	return err;
+}
+
+static int concat_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int i, err = 0;
+
+	if ((len + ofs) > mtd->size)
+		return -EINVAL;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size;
+
+		if (ofs >= subdev->size) {
+			size = 0;
+			ofs -= subdev->size;
+			continue;
+		}
+		if (ofs + len > subdev->size)
+			size = subdev->size - ofs;
+		else
+			size = len;
+
+		err = subdev->unlock(subdev, ofs, size);
+
+		if (err)
+			break;
+
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		ofs = 0;
+	}
+
+	return err;
+}
+
+static void concat_sync(struct mtd_info *mtd)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int i;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		subdev->sync(subdev);
+	}
+}
+
+static int concat_suspend(struct mtd_info *mtd)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int i, rc = 0;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		if ((rc = subdev->suspend(subdev)) < 0)
+			return rc;
+	}
+	return rc;
+}
+
+static void concat_resume(struct mtd_info *mtd)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int i;
+
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		subdev->resume(subdev);
+	}
+}
+
+/*
+ * This function constructs a virtual MTD device by concatenating
+ * num_devs MTD devices. A pointer to the new device object is
+ * stored to *new_dev upon success. This function does _not_
+ * register any devices: this is the caller's responsibility.
+ */
+struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to concatenate */
+				   int num_devs,	/* number of subdevices      */
+				   char *name)
+{				/* name for the new device   */
+	int i;
+	size_t size;
+	struct mtd_concat *concat;
+	u_int32_t max_erasesize, curr_erasesize;
+	int num_erase_region;
+
+	printk(KERN_NOTICE "Concatenating MTD devices:\n");
+	for (i = 0; i < num_devs; i++)
+		printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
+	printk(KERN_NOTICE "into device \"%s\"\n", name);
+
+	/* allocate the device structure */
+	size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
+	concat = kmalloc(size, GFP_KERNEL);
+	if (!concat) {
+		printk
+		    ("memory allocation error while creating concatenated device \"%s\"\n",
+		     name);
+		return NULL;
+	}
+	memset(concat, 0, size);
+	concat->subdev = (struct mtd_info **) (concat + 1);
+
+	/*
+	 * Set up the new "super" device's MTD object structure, check for
+	 * incompatibilites between the subdevices.
+	 */
+	concat->mtd.type = subdev[0]->type;
+	concat->mtd.flags = subdev[0]->flags;
+	concat->mtd.size = subdev[0]->size;
+	concat->mtd.erasesize = subdev[0]->erasesize;
+	concat->mtd.oobblock = subdev[0]->oobblock;
+	concat->mtd.oobsize = subdev[0]->oobsize;
+	concat->mtd.ecctype = subdev[0]->ecctype;
+	concat->mtd.eccsize = subdev[0]->eccsize;
+	if (subdev[0]->read_ecc)
+		concat->mtd.read_ecc = concat_read_ecc;
+	if (subdev[0]->write_ecc)
+		concat->mtd.write_ecc = concat_write_ecc;
+	if (subdev[0]->read_oob)
+		concat->mtd.read_oob = concat_read_oob;
+	if (subdev[0]->write_oob)
+		concat->mtd.write_oob = concat_write_oob;
+
+	concat->subdev[0] = subdev[0];
+
+	for (i = 1; i < num_devs; i++) {
+		if (concat->mtd.type != subdev[i]->type) {
+			kfree(concat);
+			printk("Incompatible device type on \"%s\"\n",
+			       subdev[i]->name);
+			return NULL;
+		}
+		if (concat->mtd.flags != subdev[i]->flags) {
+			/*
+			 * Expect all flags except MTD_WRITEABLE to be
+			 * equal on all subdevices.
+			 */
+			if ((concat->mtd.flags ^ subdev[i]->
+			     flags) & ~MTD_WRITEABLE) {
+				kfree(concat);
+				printk("Incompatible device flags on \"%s\"\n",
+				       subdev[i]->name);
+				return NULL;
+			} else
+				/* if writeable attribute differs,
+				   make super device writeable */
+				concat->mtd.flags |=
+				    subdev[i]->flags & MTD_WRITEABLE;
+		}
+		concat->mtd.size += subdev[i]->size;
+		if (concat->mtd.oobblock   !=  subdev[i]->oobblock ||
+		    concat->mtd.oobsize    !=  subdev[i]->oobsize ||
+		    concat->mtd.ecctype    !=  subdev[i]->ecctype ||
+		    concat->mtd.eccsize    !=  subdev[i]->eccsize ||
+		    !concat->mtd.read_ecc  != !subdev[i]->read_ecc ||
+		    !concat->mtd.write_ecc != !subdev[i]->write_ecc ||
+		    !concat->mtd.read_oob  != !subdev[i]->read_oob ||
+		    !concat->mtd.write_oob != !subdev[i]->write_oob) {
+			kfree(concat);
+			printk("Incompatible OOB or ECC data on \"%s\"\n",
+			       subdev[i]->name);
+			return NULL;
+		}
+		concat->subdev[i] = subdev[i];
+
+	}
+
+	concat->num_subdev = num_devs;
+	concat->mtd.name = name;
+
+	/*
+	 * NOTE: for now, we do not provide any readv()/writev() methods
+	 *       because they are messy to implement and they are not
+	 *       used to a great extent anyway.
+	 */
+	concat->mtd.erase = concat_erase;
+	concat->mtd.read = concat_read;
+	concat->mtd.write = concat_write;
+	concat->mtd.sync = concat_sync;
+	concat->mtd.lock = concat_lock;
+	concat->mtd.unlock = concat_unlock;
+	concat->mtd.suspend = concat_suspend;
+	concat->mtd.resume = concat_resume;
+
+	/*
+	 * Combine the erase block size info of the subdevices:
+	 *
+	 * first, walk the map of the new device and see how
+	 * many changes in erase size we have
+	 */
+	max_erasesize = curr_erasesize = subdev[0]->erasesize;
+	num_erase_region = 1;
+	for (i = 0; i < num_devs; i++) {
+		if (subdev[i]->numeraseregions == 0) {
+			/* current subdevice has uniform erase size */
+			if (subdev[i]->erasesize != curr_erasesize) {
+				/* if it differs from the last subdevice's erase size, count it */
+				++num_erase_region;
+				curr_erasesize = subdev[i]->erasesize;
+				if (curr_erasesize > max_erasesize)
+					max_erasesize = curr_erasesize;
+			}
+		} else {
+			/* current subdevice has variable erase size */
+			int j;
+			for (j = 0; j < subdev[i]->numeraseregions; j++) {
+
+				/* walk the list of erase regions, count any changes */
+				if (subdev[i]->eraseregions[j].erasesize !=
+				    curr_erasesize) {
+					++num_erase_region;
+					curr_erasesize =
+					    subdev[i]->eraseregions[j].
+					    erasesize;
+					if (curr_erasesize > max_erasesize)
+						max_erasesize = curr_erasesize;
+				}
+			}
+		}
+	}
+
+	if (num_erase_region == 1) {
+		/*
+		 * All subdevices have the same uniform erase size.
+		 * This is easy:
+		 */
+		concat->mtd.erasesize = curr_erasesize;
+		concat->mtd.numeraseregions = 0;
+	} else {
+		/*
+		 * erase block size varies across the subdevices: allocate
+		 * space to store the data describing the variable erase regions
+		 */
+		struct mtd_erase_region_info *erase_region_p;
+		u_int32_t begin, position;
+
+		concat->mtd.erasesize = max_erasesize;
+		concat->mtd.numeraseregions = num_erase_region;
+		concat->mtd.eraseregions = erase_region_p =
+		    kmalloc(num_erase_region *
+			    sizeof (struct mtd_erase_region_info), GFP_KERNEL);
+		if (!erase_region_p) {
+			kfree(concat);
+			printk
+			    ("memory allocation error while creating erase region list"
+			     " for device \"%s\"\n", name);
+			return NULL;
+		}
+
+		/*
+		 * walk the map of the new device once more and fill in
+		 * in erase region info:
+		 */
+		curr_erasesize = subdev[0]->erasesize;
+		begin = position = 0;
+		for (i = 0; i < num_devs; i++) {
+			if (subdev[i]->numeraseregions == 0) {
+				/* current subdevice has uniform erase size */
+				if (subdev[i]->erasesize != curr_erasesize) {
+					/*
+					 *  fill in an mtd_erase_region_info structure for the area
+					 *  we have walked so far:
+					 */
+					erase_region_p->offset = begin;
+					erase_region_p->erasesize =
+					    curr_erasesize;
+					erase_region_p->numblocks =
+					    (position - begin) / curr_erasesize;
+					begin = position;
+
+					curr_erasesize = subdev[i]->erasesize;
+					++erase_region_p;
+				}
+				position += subdev[i]->size;
+			} else {
+				/* current subdevice has variable erase size */
+				int j;
+				for (j = 0; j < subdev[i]->numeraseregions; j++) {
+					/* walk the list of erase regions, count any changes */
+					if (subdev[i]->eraseregions[j].
+					    erasesize != curr_erasesize) {
+						erase_region_p->offset = begin;
+						erase_region_p->erasesize =
+						    curr_erasesize;
+						erase_region_p->numblocks =
+						    (position -
+						     begin) / curr_erasesize;
+						begin = position;
+
+						curr_erasesize =
+						    subdev[i]->eraseregions[j].
+						    erasesize;
+						++erase_region_p;
+					}
+					position +=
+					    subdev[i]->eraseregions[j].
+					    numblocks * curr_erasesize;
+				}
+			}
+		}
+		/* Now write the final entry */
+		erase_region_p->offset = begin;
+		erase_region_p->erasesize = curr_erasesize;
+		erase_region_p->numblocks = (position - begin) / curr_erasesize;
+	}
+
+	return &concat->mtd;
+}
+
+/* 
+ * This function destroys an MTD object obtained from concat_mtd_devs()
+ */
+
+void mtd_concat_destroy(struct mtd_info *mtd)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	if (concat->mtd.numeraseregions)
+		kfree(concat->mtd.eraseregions);
+	kfree(concat);
+}
+
+EXPORT_SYMBOL(mtd_concat_create);
+EXPORT_SYMBOL(mtd_concat_destroy);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
+MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");