Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 662 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
new file mode 100644
index 000000000..b108e1f04
--- /dev/null
+++ b/drivers/mtd/ubi/debug.c
@@ -0,0 +1,662 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#include "ubi.h"
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+
+
+/**
+ * ubi_dump_flash - dump a region of flash.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to dump
+ * @offset: the starting offset within the physical eraseblock to dump
+ * @len: the length of the region to dump
+ */
+void ubi_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len)
+{
+	int err;
+	size_t read;
+	void *buf;
+	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
+
+	buf = vmalloc(len);
+	if (!buf)
+		return;
+	err = mtd_read(ubi->mtd, addr, len, &read, buf);
+	if (err && err != -EUCLEAN) {
+		ubi_err(ubi, "err %d while reading %d bytes from PEB %d:%d, read %zd bytes",
+			err, len, pnum, offset, read);
+		goto out;
+	}
+
+	ubi_msg(ubi, "dumping %d bytes of data from PEB %d, offset %d",
+		len, pnum, offset);
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
+out:
+	vfree(buf);
+	return;
+}
+
+/**
+ * ubi_dump_ec_hdr - dump an erase counter header.
+ * @ec_hdr: the erase counter header to dump
+ */
+void ubi_dump_ec_hdr(const struct ubi_ec_hdr *ec_hdr)
+{
+	pr_err("Erase counter header dump:\n");
+	pr_err("\tmagic          %#08x\n", be32_to_cpu(ec_hdr->magic));
+	pr_err("\tversion        %d\n", (int)ec_hdr->version);
+	pr_err("\tec             %llu\n", (long long)be64_to_cpu(ec_hdr->ec));
+	pr_err("\tvid_hdr_offset %d\n", be32_to_cpu(ec_hdr->vid_hdr_offset));
+	pr_err("\tdata_offset    %d\n", be32_to_cpu(ec_hdr->data_offset));
+	pr_err("\timage_seq      %d\n", be32_to_cpu(ec_hdr->image_seq));
+	pr_err("\thdr_crc        %#08x\n", be32_to_cpu(ec_hdr->hdr_crc));
+	pr_err("erase counter header hexdump:\n");
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+		       ec_hdr, UBI_EC_HDR_SIZE, 1);
+}
+
+/**
+ * ubi_dump_vid_hdr - dump a volume identifier header.
+ * @vid_hdr: the volume identifier header to dump
+ */
+void ubi_dump_vid_hdr(const struct ubi_vid_hdr *vid_hdr)
+{
+	pr_err("Volume identifier header dump:\n");
+	pr_err("\tmagic     %08x\n", be32_to_cpu(vid_hdr->magic));
+	pr_err("\tversion   %d\n",  (int)vid_hdr->version);
+	pr_err("\tvol_type  %d\n",  (int)vid_hdr->vol_type);
+	pr_err("\tcopy_flag %d\n",  (int)vid_hdr->copy_flag);
+	pr_err("\tcompat    %d\n",  (int)vid_hdr->compat);
+	pr_err("\tvol_id    %d\n",  be32_to_cpu(vid_hdr->vol_id));
+	pr_err("\tlnum      %d\n",  be32_to_cpu(vid_hdr->lnum));
+	pr_err("\tdata_size %d\n",  be32_to_cpu(vid_hdr->data_size));
+	pr_err("\tused_ebs  %d\n",  be32_to_cpu(vid_hdr->used_ebs));
+	pr_err("\tdata_pad  %d\n",  be32_to_cpu(vid_hdr->data_pad));
+	pr_err("\tsqnum     %llu\n",
+		(unsigned long long)be64_to_cpu(vid_hdr->sqnum));
+	pr_err("\thdr_crc   %08x\n", be32_to_cpu(vid_hdr->hdr_crc));
+	pr_err("Volume identifier header hexdump:\n");
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+		       vid_hdr, UBI_VID_HDR_SIZE, 1);
+}
+
+/**
+ * ubi_dump_vol_info - dump volume information.
+ * @vol: UBI volume description object
+ */
+void ubi_dump_vol_info(const struct ubi_volume *vol)
+{
+	pr_err("Volume information dump:\n");
+	pr_err("\tvol_id          %d\n", vol->vol_id);
+	pr_err("\treserved_pebs   %d\n", vol->reserved_pebs);
+	pr_err("\talignment       %d\n", vol->alignment);
+	pr_err("\tdata_pad        %d\n", vol->data_pad);
+	pr_err("\tvol_type        %d\n", vol->vol_type);
+	pr_err("\tname_len        %d\n", vol->name_len);
+	pr_err("\tusable_leb_size %d\n", vol->usable_leb_size);
+	pr_err("\tused_ebs        %d\n", vol->used_ebs);
+	pr_err("\tused_bytes      %lld\n", vol->used_bytes);
+	pr_err("\tlast_eb_bytes   %d\n", vol->last_eb_bytes);
+	pr_err("\tcorrupted       %d\n", vol->corrupted);
+	pr_err("\tupd_marker      %d\n", vol->upd_marker);
+
+	if (vol->name_len <= UBI_VOL_NAME_MAX &&
+	    strnlen(vol->name, vol->name_len + 1) == vol->name_len) {
+		pr_err("\tname            %s\n", vol->name);
+	} else {
+		pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
+		       vol->name[0], vol->name[1], vol->name[2],
+		       vol->name[3], vol->name[4]);
+	}
+}
+
+/**
+ * ubi_dump_vtbl_record - dump a &struct ubi_vtbl_record object.
+ * @r: the object to dump
+ * @idx: volume table index
+ */
+void ubi_dump_vtbl_record(const struct ubi_vtbl_record *r, int idx)
+{
+	int name_len = be16_to_cpu(r->name_len);
+
+	pr_err("Volume table record %d dump:\n", idx);
+	pr_err("\treserved_pebs   %d\n", be32_to_cpu(r->reserved_pebs));
+	pr_err("\talignment       %d\n", be32_to_cpu(r->alignment));
+	pr_err("\tdata_pad        %d\n", be32_to_cpu(r->data_pad));
+	pr_err("\tvol_type        %d\n", (int)r->vol_type);
+	pr_err("\tupd_marker      %d\n", (int)r->upd_marker);
+	pr_err("\tname_len        %d\n", name_len);
+
+	if (r->name[0] == '\0') {
+		pr_err("\tname            NULL\n");
+		return;
+	}
+
+	if (name_len <= UBI_VOL_NAME_MAX &&
+	    strnlen(&r->name[0], name_len + 1) == name_len) {
+		pr_err("\tname            %s\n", &r->name[0]);
+	} else {
+		pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
+			r->name[0], r->name[1], r->name[2], r->name[3],
+			r->name[4]);
+	}
+	pr_err("\tcrc             %#08x\n", be32_to_cpu(r->crc));
+}
+
+/**
+ * ubi_dump_av - dump a &struct ubi_ainf_volume object.
+ * @av: the object to dump
+ */
+void ubi_dump_av(const struct ubi_ainf_volume *av)
+{
+	pr_err("Volume attaching information dump:\n");
+	pr_err("\tvol_id         %d\n", av->vol_id);
+	pr_err("\thighest_lnum   %d\n", av->highest_lnum);
+	pr_err("\tleb_count      %d\n", av->leb_count);
+	pr_err("\tcompat         %d\n", av->compat);
+	pr_err("\tvol_type       %d\n", av->vol_type);
+	pr_err("\tused_ebs       %d\n", av->used_ebs);
+	pr_err("\tlast_data_size %d\n", av->last_data_size);
+	pr_err("\tdata_pad       %d\n", av->data_pad);
+}
+
+/**
+ * ubi_dump_aeb - dump a &struct ubi_ainf_peb object.
+ * @aeb: the object to dump
+ * @type: object type: 0 - not corrupted, 1 - corrupted
+ */
+void ubi_dump_aeb(const struct ubi_ainf_peb *aeb, int type)
+{
+	pr_err("eraseblock attaching information dump:\n");
+	pr_err("\tec       %d\n", aeb->ec);
+	pr_err("\tpnum     %d\n", aeb->pnum);
+	if (type == 0) {
+		pr_err("\tlnum     %d\n", aeb->lnum);
+		pr_err("\tscrub    %d\n", aeb->scrub);
+		pr_err("\tsqnum    %llu\n", aeb->sqnum);
+	}
+}
+
+/**
+ * ubi_dump_mkvol_req - dump a &struct ubi_mkvol_req object.
+ * @req: the object to dump
+ */
+void ubi_dump_mkvol_req(const struct ubi_mkvol_req *req)
+{
+	char nm[17];
+
+	pr_err("Volume creation request dump:\n");
+	pr_err("\tvol_id    %d\n",   req->vol_id);
+	pr_err("\talignment %d\n",   req->alignment);
+	pr_err("\tbytes     %lld\n", (long long)req->bytes);
+	pr_err("\tvol_type  %d\n",   req->vol_type);
+	pr_err("\tname_len  %d\n",   req->name_len);
+
+	memcpy(nm, req->name, 16);
+	nm[16] = 0;
+	pr_err("\t1st 16 characters of name: %s\n", nm);
+}
+
+/*
+ * Root directory for UBI stuff in debugfs. Contains sub-directories which
+ * contain the stuff specific to particular UBI devices.
+ */
+static struct dentry *dfs_rootdir;
+
+/**
+ * ubi_debugfs_init - create UBI debugfs directory.
+ *
+ * Create UBI debugfs directory. Returns zero in case of success and a negative
+ * error code in case of failure.
+ */
+int ubi_debugfs_init(void)
+{
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
+
+	dfs_rootdir = debugfs_create_dir("ubi", NULL);
+	if (IS_ERR_OR_NULL(dfs_rootdir)) {
+		int err = dfs_rootdir ? PTR_ERR(dfs_rootdir) : -ENODEV;
+
+		pr_err("UBI error: cannot create \"ubi\" debugfs directory, error %d\n",
+		       err);
+		return err;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_debugfs_exit - remove UBI debugfs directory.
+ */
+void ubi_debugfs_exit(void)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		debugfs_remove(dfs_rootdir);
+}
+
+/* Read an UBI debugfs file */
+static ssize_t dfs_file_read(struct file *file, char __user *user_buf,
+			     size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	char buf[8];
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = &ubi->dbg;
+
+	if (dent == d->dfs_chk_gen)
+		val = d->chk_gen;
+	else if (dent == d->dfs_chk_io)
+		val = d->chk_io;
+	else if (dent == d->dfs_chk_fastmap)
+		val = d->chk_fastmap;
+	else if (dent == d->dfs_disable_bgt)
+		val = d->disable_bgt;
+	else if (dent == d->dfs_emulate_bitflips)
+		val = d->emulate_bitflips;
+	else if (dent == d->dfs_emulate_io_failures)
+		val = d->emulate_io_failures;
+	else if (dent == d->dfs_emulate_power_cut) {
+		snprintf(buf, sizeof(buf), "%u\n", d->emulate_power_cut);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} else if (dent == d->dfs_power_cut_min) {
+		snprintf(buf, sizeof(buf), "%u\n", d->power_cut_min);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} else if (dent == d->dfs_power_cut_max) {
+		snprintf(buf, sizeof(buf), "%u\n", d->power_cut_max);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	}
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (val)
+		buf[0] = '1';
+	else
+		buf[0] = '0';
+	buf[1] = '\n';
+	buf[2] = 0x00;
+
+	count = simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+/* Write an UBI debugfs file */
+static ssize_t dfs_file_write(struct file *file, const char __user *user_buf,
+			      size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	size_t buf_size;
+	char buf[8] = {0};
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = &ubi->dbg;
+
+	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
+	if (copy_from_user(buf, user_buf, buf_size)) {
+		count = -EFAULT;
+		goto out;
+	}
+
+	if (dent == d->dfs_power_cut_min) {
+		if (kstrtouint(buf, 0, &d->power_cut_min) != 0)
+			count = -EINVAL;
+		goto out;
+	} else if (dent == d->dfs_power_cut_max) {
+		if (kstrtouint(buf, 0, &d->power_cut_max) != 0)
+			count = -EINVAL;
+		goto out;
+	} else if (dent == d->dfs_emulate_power_cut) {
+		if (kstrtoint(buf, 0, &val) != 0)
+			count = -EINVAL;
+		else
+			d->emulate_power_cut = val;
+		goto out;
+	}
+
+	if (buf[0] == '1')
+		val = 1;
+	else if (buf[0] == '0')
+		val = 0;
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (dent == d->dfs_chk_gen)
+		d->chk_gen = val;
+	else if (dent == d->dfs_chk_io)
+		d->chk_io = val;
+	else if (dent == d->dfs_chk_fastmap)
+		d->chk_fastmap = val;
+	else if (dent == d->dfs_disable_bgt)
+		d->disable_bgt = val;
+	else if (dent == d->dfs_emulate_bitflips)
+		d->emulate_bitflips = val;
+	else if (dent == d->dfs_emulate_io_failures)
+		d->emulate_io_failures = val;
+	else
+		count = -EINVAL;
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+/* File operations for all UBI debugfs files except
+ * detailed_erase_block_info
+ */
+static const struct file_operations dfs_fops = {
+	.read   = dfs_file_read,
+	.write  = dfs_file_write,
+	.open	= simple_open,
+	.llseek = no_llseek,
+	.owner  = THIS_MODULE,
+};
+
+/* As long as the position is less then that total number of erase blocks,
+ * we still have more to print.
+ */
+static void *eraseblk_count_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct ubi_device *ubi = s->private;
+
+	if (*pos < ubi->peb_count)
+		return pos;
+
+	return NULL;
+}
+
+/* Since we are using the position as the iterator, we just need to check if we
+ * are done and increment the position.
+ */
+static void *eraseblk_count_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct ubi_device *ubi = s->private;
+
+	(*pos)++;
+
+	if (*pos < ubi->peb_count)
+		return pos;
+
+	return NULL;
+}
+
+static void eraseblk_count_seq_stop(struct seq_file *s, void *v)
+{
+}
+
+static int eraseblk_count_seq_show(struct seq_file *s, void *iter)
+{
+	struct ubi_device *ubi = s->private;
+	struct ubi_wl_entry *wl;
+	int *block_number = iter;
+	int erase_count = -1;
+	int err;
+
+	/* If this is the start, print a header */
+	if (*block_number == 0)
+		seq_puts(s, "physical_block_number\terase_count\n");
+
+	err = ubi_io_is_bad(ubi, *block_number);
+	if (err)
+		return err;
+
+	spin_lock(&ubi->wl_lock);
+
+	wl = ubi->lookuptbl[*block_number];
+	if (wl)
+		erase_count = wl->ec;
+
+	spin_unlock(&ubi->wl_lock);
+
+	if (erase_count < 0)
+		return 0;
+
+	seq_printf(s, "%-22d\t%-11d\n", *block_number, erase_count);
+
+	return 0;
+}
+
+static const struct seq_operations eraseblk_count_seq_ops = {
+	.start = eraseblk_count_seq_start,
+	.next = eraseblk_count_seq_next,
+	.stop = eraseblk_count_seq_stop,
+	.show = eraseblk_count_seq_show
+};
+
+static int eraseblk_count_open(struct inode *inode, struct file *f)
+{
+	struct seq_file *s;
+	int err;
+
+	err = seq_open(f, &eraseblk_count_seq_ops);
+	if (err)
+		return err;
+
+	s = f->private_data;
+	s->private = ubi_get_device((unsigned long)inode->i_private);
+
+	if (!s->private)
+		return -ENODEV;
+	else
+		return 0;
+}
+
+static int eraseblk_count_release(struct inode *inode, struct file *f)
+{
+	struct seq_file *s = f->private_data;
+	struct ubi_device *ubi = s->private;
+
+	ubi_put_device(ubi);
+
+	return seq_release(inode, f);
+}
+
+static const struct file_operations eraseblk_count_fops = {
+	.owner = THIS_MODULE,
+	.open = eraseblk_count_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = eraseblk_count_release,
+};
+
+/**
+ * ubi_debugfs_init_dev - initialize debugfs for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function creates all debugfs files for UBI device @ubi. Returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+int ubi_debugfs_init_dev(struct ubi_device *ubi)
+{
+	int err, n;
+	unsigned long ubi_num = ubi->ubi_num;
+	const char *fname;
+	struct dentry *dent;
+	struct ubi_debug_info *d = &ubi->dbg;
+
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
+
+	n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN + 1, UBI_DFS_DIR_NAME,
+		     ubi->ubi_num);
+	if (n == UBI_DFS_DIR_LEN) {
+		/* The array size is too small */
+		fname = UBI_DFS_DIR_NAME;
+		dent = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	fname = d->dfs_dir_name;
+	dent = debugfs_create_dir(fname, dfs_rootdir);
+	if (IS_ERR_OR_NULL(dent))
+		goto out;
+	d->dfs_dir = dent;
+
+	fname = "chk_gen";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_gen = dent;
+
+	fname = "chk_io";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_io = dent;
+
+	fname = "chk_fastmap";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_fastmap = dent;
+
+	fname = "tst_disable_bgt";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_disable_bgt = dent;
+
+	fname = "tst_emulate_bitflips";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_emulate_bitflips = dent;
+
+	fname = "tst_emulate_io_failures";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_emulate_io_failures = dent;
+
+	fname = "tst_emulate_power_cut";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_emulate_power_cut = dent;
+
+	fname = "tst_emulate_power_cut_min";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_power_cut_min = dent;
+
+	fname = "tst_emulate_power_cut_max";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_power_cut_max = dent;
+
+	fname = "detailed_erase_block_info";
+	dent = debugfs_create_file(fname, S_IRUSR, d->dfs_dir, (void *)ubi_num,
+				   &eraseblk_count_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+
+	return 0;
+
+out_remove:
+	debugfs_remove_recursive(d->dfs_dir);
+out:
+	err = dent ? PTR_ERR(dent) : -ENODEV;
+	ubi_err(ubi, "cannot create \"%s\" debugfs file or directory, error %d\n",
+		fname, err);
+	return err;
+}
+
+/**
+ * dbg_debug_exit_dev - free all debugfs files corresponding to device @ubi
+ * @ubi: UBI device description object
+ */
+void ubi_debugfs_exit_dev(struct ubi_device *ubi)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		debugfs_remove_recursive(ubi->dbg.dfs_dir);
+}
+
+/**
+ * ubi_dbg_power_cut - emulate a power cut if it is time to do so
+ * @ubi: UBI device description object
+ * @caller: Flags set to indicate from where the function is being called
+ *
+ * Returns non-zero if a power cut was emulated, zero if not.
+ */
+int ubi_dbg_power_cut(struct ubi_device *ubi, int caller)
+{
+	unsigned int range;
+
+	if ((ubi->dbg.emulate_power_cut & caller) == 0)
+		return 0;
+
+	if (ubi->dbg.power_cut_counter == 0) {
+		ubi->dbg.power_cut_counter = ubi->dbg.power_cut_min;
+
+		if (ubi->dbg.power_cut_max > ubi->dbg.power_cut_min) {
+			range = ubi->dbg.power_cut_max - ubi->dbg.power_cut_min;
+			ubi->dbg.power_cut_counter += prandom_u32() % range;
+		}
+		return 0;
+	}
+
+	ubi->dbg.power_cut_counter--;
+	if (ubi->dbg.power_cut_counter)
+		return 0;
+
+	ubi_msg(ubi, "XXXXXXXXXXXXXXX emulating a power cut XXXXXXXXXXXXXXXX");
+	ubi_ro_mode(ubi);
+	return 1;
+}