1 files changed, 500 insertions, 0 deletions
diff --git a/drivers/mtd/ubi/gluebi.c b/drivers/mtd/ubi/gluebi.c
new file mode 100644
index 000000000..1b980d15d
--- /dev/null
+++ b/drivers/mtd/ubi/gluebi.c
@@ -0,0 +1,500 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
+ */
+
+/*
+ * This is a small driver which implements fake MTD devices on top of UBI
+ * volumes. This sounds strange, but it is in fact quite useful to make
+ * MTD-oriented software (including all the legacy software) work on top of
+ * UBI.
+ *
+ * Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
+ * size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
+ * eraseblock size is equivalent to the logical eraseblock size of the volume.
+ */
+
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/mtd/ubi.h>
+#include <linux/mtd/mtd.h>
+#include "ubi-media.h"
+
+#define err_msg(fmt, ...)                                   \
+	pr_err("gluebi (pid %d): %s: " fmt "\n",            \
+	       current->pid, __func__, ##__VA_ARGS__)
+
+/**
+ * struct gluebi_device - a gluebi device description data structure.
+ * @mtd: emulated MTD device description object
+ * @refcnt: gluebi device reference count
+ * @desc: UBI volume descriptor
+ * @ubi_num: UBI device number this gluebi device works on
+ * @vol_id: ID of UBI volume this gluebi device works on
+ * @list: link in a list of gluebi devices
+ */
+struct gluebi_device {
+	struct mtd_info mtd;
+	int refcnt;
+	struct ubi_volume_desc *desc;
+	int ubi_num;
+	int vol_id;
+	struct list_head list;
+};
+
+/* List of all gluebi devices */
+static LIST_HEAD(gluebi_devices);
+static DEFINE_MUTEX(devices_mutex);
+
+/**
+ * find_gluebi_nolock - find a gluebi device.
+ * @ubi_num: UBI device number
+ * @vol_id: volume ID
+ *
+ * This function seraches for gluebi device corresponding to UBI device
+ * @ubi_num and UBI volume @vol_id. Returns the gluebi device description
+ * object in case of success and %NULL in case of failure. The caller has to
+ * have the &devices_mutex locked.
+ */
+static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
+{
+	struct gluebi_device *gluebi;
+
+	list_for_each_entry(gluebi, &gluebi_devices, list)
+		if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
+			return gluebi;
+	return NULL;
+}
+
+/**
+ * gluebi_get_device - get MTD device reference.
+ * @mtd: the MTD device description object
+ *
+ * This function is called every time the MTD device is being opened and
+ * implements the MTD get_device() operation. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+static int gluebi_get_device(struct mtd_info *mtd)
+{
+	struct gluebi_device *gluebi;
+	int ubi_mode = UBI_READONLY;
+
+	if (mtd->flags & MTD_WRITEABLE)
+		ubi_mode = UBI_READWRITE;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	mutex_lock(&devices_mutex);
+	if (gluebi->refcnt > 0) {
+		/*
+		 * The MTD device is already referenced and this is just one
+		 * more reference. MTD allows many users to open the same
+		 * volume simultaneously and do not distinguish between
+		 * readers/writers/exclusive/meta openers as UBI does. So we do
+		 * not open the UBI volume again - just increase the reference
+		 * counter and return.
+		 */
+		gluebi->refcnt += 1;
+		mutex_unlock(&devices_mutex);
+		return 0;
+	}
+
+	/*
+	 * This is the first reference to this UBI volume via the MTD device
+	 * interface. Open the corresponding volume in read-write mode.
+	 */
+	gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
+				       ubi_mode);
+	if (IS_ERR(gluebi->desc)) {
+		mutex_unlock(&devices_mutex);
+		return PTR_ERR(gluebi->desc);
+	}
+	gluebi->refcnt += 1;
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_put_device - put MTD device reference.
+ * @mtd: the MTD device description object
+ *
+ * This function is called every time the MTD device is being put. Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+static void gluebi_put_device(struct mtd_info *mtd)
+{
+	struct gluebi_device *gluebi;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	mutex_lock(&devices_mutex);
+	gluebi->refcnt -= 1;
+	if (gluebi->refcnt == 0)
+		ubi_close_volume(gluebi->desc);
+	mutex_unlock(&devices_mutex);
+}
+
+/**
+ * gluebi_read - read operation of emulated MTD devices.
+ * @mtd: MTD device description object
+ * @from: absolute offset from where to read
+ * @len: how many bytes to read
+ * @retlen: count of read bytes is returned here
+ * @buf: buffer to store the read data
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
+		       size_t *retlen, unsigned char *buf)
+{
+	int err = 0, lnum, offs, bytes_left;
+	struct gluebi_device *gluebi;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	lnum = div_u64_rem(from, mtd->erasesize, &offs);
+	bytes_left = len;
+	while (bytes_left) {
+		size_t to_read = mtd->erasesize - offs;
+
+		if (to_read > bytes_left)
+			to_read = bytes_left;
+
+		err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
+		if (err)
+			break;
+
+		lnum += 1;
+		offs = 0;
+		bytes_left -= to_read;
+		buf += to_read;
+	}
+
+	*retlen = len - bytes_left;
+	return err;
+}
+
+/**
+ * gluebi_write - write operation of emulated MTD devices.
+ * @mtd: MTD device description object
+ * @to: absolute offset where to write
+ * @len: how many bytes to write
+ * @retlen: count of written bytes is returned here
+ * @buf: buffer with data to write
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
+			size_t *retlen, const u_char *buf)
+{
+	int err = 0, lnum, offs, bytes_left;
+	struct gluebi_device *gluebi;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	lnum = div_u64_rem(to, mtd->erasesize, &offs);
+
+	if (len % mtd->writesize || offs % mtd->writesize)
+		return -EINVAL;
+
+	bytes_left = len;
+	while (bytes_left) {
+		size_t to_write = mtd->erasesize - offs;
+
+		if (to_write > bytes_left)
+			to_write = bytes_left;
+
+		err = ubi_leb_write(gluebi->desc, lnum, buf, offs, to_write);
+		if (err)
+			break;
+
+		lnum += 1;
+		offs = 0;
+		bytes_left -= to_write;
+		buf += to_write;
+	}
+
+	*retlen = len - bytes_left;
+	return err;
+}
+
+/**
+ * gluebi_erase - erase operation of emulated MTD devices.
+ * @mtd: the MTD device description object
+ * @instr: the erase operation description
+ *
+ * This function calls the erase callback when finishes. Returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+	int err, i, lnum, count;
+	struct gluebi_device *gluebi;
+
+	if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
+		return -EINVAL;
+
+	lnum = mtd_div_by_eb(instr->addr, mtd);
+	count = mtd_div_by_eb(instr->len, mtd);
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+
+	for (i = 0; i < count - 1; i++) {
+		err = ubi_leb_unmap(gluebi->desc, lnum + i);
+		if (err)
+			goto out_err;
+	}
+	/*
+	 * MTD erase operations are synchronous, so we have to make sure the
+	 * physical eraseblock is wiped out.
+	 *
+	 * Thus, perform leb_erase instead of leb_unmap operation - leb_erase
+	 * will wait for the end of operations
+	 */
+	err = ubi_leb_erase(gluebi->desc, lnum + i);
+	if (err)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	instr->fail_addr = (long long)lnum * mtd->erasesize;
+	return err;
+}
+
+/**
+ * gluebi_create - create a gluebi device for an UBI volume.
+ * @di: UBI device description object
+ * @vi: UBI volume description object
+ *
+ * This function is called when a new UBI volume is created in order to create
+ * corresponding fake MTD device. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int gluebi_create(struct ubi_device_info *di,
+			 struct ubi_volume_info *vi)
+{
+	struct gluebi_device *gluebi, *g;
+	struct mtd_info *mtd;
+
+	gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
+	if (!gluebi)
+		return -ENOMEM;
+
+	mtd = &gluebi->mtd;
+	mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
+	if (!mtd->name) {
+		kfree(gluebi);
+		return -ENOMEM;
+	}
+
+	gluebi->vol_id = vi->vol_id;
+	gluebi->ubi_num = vi->ubi_num;
+	mtd->type = MTD_UBIVOLUME;
+	if (!di->ro_mode)
+		mtd->flags = MTD_WRITEABLE;
+	mtd->owner      = THIS_MODULE;
+	mtd->writesize  = di->min_io_size;
+	mtd->erasesize  = vi->usable_leb_size;
+	mtd->_read       = gluebi_read;
+	mtd->_write      = gluebi_write;
+	mtd->_erase      = gluebi_erase;
+	mtd->_get_device = gluebi_get_device;
+	mtd->_put_device = gluebi_put_device;
+
+	/*
+	 * In case of dynamic a volume, MTD device size is just volume size. In
+	 * case of a static volume the size is equivalent to the amount of data
+	 * bytes.
+	 */
+	if (vi->vol_type == UBI_DYNAMIC_VOLUME)
+		mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
+	else
+		mtd->size = vi->used_bytes;
+
+	/* Just a sanity check - make sure this gluebi device does not exist */
+	mutex_lock(&devices_mutex);
+	g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (g)
+		err_msg("gluebi MTD device %d form UBI device %d volume %d already exists",
+			g->mtd.index, vi->ubi_num, vi->vol_id);
+	mutex_unlock(&devices_mutex);
+
+	if (mtd_device_register(mtd, NULL, 0)) {
+		err_msg("cannot add MTD device");
+		kfree(mtd->name);
+		kfree(gluebi);
+		return -ENFILE;
+	}
+
+	mutex_lock(&devices_mutex);
+	list_add_tail(&gluebi->list, &gluebi_devices);
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_remove - remove a gluebi device.
+ * @vi: UBI volume description object
+ *
+ * This function is called when an UBI volume is removed and it removes
+ * corresponding fake MTD device. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int gluebi_remove(struct ubi_volume_info *vi)
+{
+	int err = 0;
+	struct mtd_info *mtd;
+	struct gluebi_device *gluebi;
+
+	mutex_lock(&devices_mutex);
+	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (!gluebi) {
+		err_msg("got remove notification for unknown UBI device %d volume %d",
+			vi->ubi_num, vi->vol_id);
+		err = -ENOENT;
+	} else if (gluebi->refcnt)
+		err = -EBUSY;
+	else
+		list_del(&gluebi->list);
+	mutex_unlock(&devices_mutex);
+	if (err)
+		return err;
+
+	mtd = &gluebi->mtd;
+	err = mtd_device_unregister(mtd);
+	if (err) {
+		err_msg("cannot remove fake MTD device %d, UBI device %d, volume %d, error %d",
+			mtd->index, gluebi->ubi_num, gluebi->vol_id, err);
+		mutex_lock(&devices_mutex);
+		list_add_tail(&gluebi->list, &gluebi_devices);
+		mutex_unlock(&devices_mutex);
+		return err;
+	}
+
+	kfree(mtd->name);
+	kfree(gluebi);
+	return 0;
+}
+
+/**
+ * gluebi_updated - UBI volume was updated notifier.
+ * @vi: volume info structure
+ *
+ * This function is called every time an UBI volume is updated. It does nothing
+ * if te volume @vol is dynamic, and changes MTD device size if the
+ * volume is static. This is needed because static volumes cannot be read past
+ * data they contain. This function returns zero in case of success and a
+ * negative error code in case of error.
+ */
+static int gluebi_updated(struct ubi_volume_info *vi)
+{
+	struct gluebi_device *gluebi;
+
+	mutex_lock(&devices_mutex);
+	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (!gluebi) {
+		mutex_unlock(&devices_mutex);
+		err_msg("got update notification for unknown UBI device %d volume %d",
+			vi->ubi_num, vi->vol_id);
+		return -ENOENT;
+	}
+
+	if (vi->vol_type == UBI_STATIC_VOLUME)
+		gluebi->mtd.size = vi->used_bytes;
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_resized - UBI volume was re-sized notifier.
+ * @vi: volume info structure
+ *
+ * This function is called every time an UBI volume is re-size. It changes the
+ * corresponding fake MTD device size. This function returns zero in case of
+ * success and a negative error code in case of error.
+ */
+static int gluebi_resized(struct ubi_volume_info *vi)
+{
+	struct gluebi_device *gluebi;
+
+	mutex_lock(&devices_mutex);
+	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (!gluebi) {
+		mutex_unlock(&devices_mutex);
+		err_msg("got update notification for unknown UBI device %d volume %d",
+			vi->ubi_num, vi->vol_id);
+		return -ENOENT;
+	}
+	gluebi->mtd.size = vi->used_bytes;
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_notify - UBI notification handler.
+ * @nb: registered notifier block
+ * @l: notification type
+ * @ns_ptr: pointer to the &struct ubi_notification object
+ */
+static int gluebi_notify(struct notifier_block *nb, unsigned long l,
+			 void *ns_ptr)
+{
+	struct ubi_notification *nt = ns_ptr;
+
+	switch (l) {
+	case UBI_VOLUME_ADDED:
+		gluebi_create(&nt->di, &nt->vi);
+		break;
+	case UBI_VOLUME_REMOVED:
+		gluebi_remove(&nt->vi);
+		break;
+	case UBI_VOLUME_RESIZED:
+		gluebi_resized(&nt->vi);
+		break;
+	case UBI_VOLUME_UPDATED:
+		gluebi_updated(&nt->vi);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block gluebi_notifier = {
+	.notifier_call	= gluebi_notify,
+};
+
+static int __init ubi_gluebi_init(void)
+{
+	return ubi_register_volume_notifier(&gluebi_notifier, 0);
+}
+
+static void __exit ubi_gluebi_exit(void)
+{
+	struct gluebi_device *gluebi, *g;
+
+	list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
+		int err;
+		struct mtd_info *mtd = &gluebi->mtd;
+
+		err = mtd_device_unregister(mtd);
+		if (err)
+			err_msg("error %d while removing gluebi MTD device %d, UBI device %d, volume %d - ignoring",
+				err, mtd->index, gluebi->ubi_num,
+				gluebi->vol_id);
+		kfree(mtd->name);
+		kfree(gluebi);
+	}
+	ubi_unregister_volume_notifier(&gluebi_notifier);
+}
+
+module_init(ubi_gluebi_init);
+module_exit(ubi_gluebi_exit);
+MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
+MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
+MODULE_LICENSE("GPL");