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Subject[PATCH 5/5] mtd: nand: nandsim: add support for power-cut emulation
Date
Add support for power-cut emulation on program and erase operations.

This power-cut emulation is configurable through the nandsim/powercut file
exposed in debugfs and can be triggered on erase or program operations.
The user can also specify a specific block and/or page (relative to a
block) at which he wants the power-cut to occur.

Here are some configuration examples:

disabled => the power-cut emulation is disabled
on-erase => power-cut emulation is active and triggered on all erase
operations
on-erase:12 => power-cut emulation is active and triggered each time block
12 is accessed
on-program => power-cut emulation is active and triggered each time a page
is programmed
on-program::5 => power-cut emulation is active and triggered each time page
5 of any block is programmed
on-program:12:5 => power-cut emulation is active and triggered each time
page 5 of block 12 is programmed

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
drivers/mtd/nand/nandsim.c | 172 ++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 162 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c
index efd8763..2f3f674 100644
--- a/drivers/mtd/nand/nandsim.c
+++ b/drivers/mtd/nand/nandsim.c
@@ -289,6 +289,7 @@ MODULE_PARM_DESC(bch, "Enable BCH ecc and set how many bits should "
struct nandsim_debug_info {
struct dentry *dfs_root;
struct dentry *dfs_wear_report;
+ struct dentry *dfs_powercut;
};

/*
@@ -299,6 +300,24 @@ union ns_mem {
uint16_t *word; /* for 16-bit word access */
};

+enum ns_powercut_status {
+ NS_POWER_CUT_DISABLED,
+ NS_POWER_CUT_ON_ERASE,
+ NS_POWER_CUT_ON_PROGRAM,
+};
+
+struct ns_powercut {
+ enum ns_powercut_status status;
+ int block;
+ int page;
+};
+
+static struct ns_powercut powercut_info = {
+ .status = NS_POWER_CUT_DISABLED,
+ .block = -1,
+ .page = -1,
+};
+
/*
* The structure which describes all the internal simulator data.
*/
@@ -369,6 +388,7 @@ struct nandsim {
void *file_buf;
struct page *held_pages[NS_MAX_HELD_PAGES];
int held_cnt;
+ bool powercut;

struct nandsim_debug_info dbg;
};
@@ -514,6 +534,78 @@ static const struct file_operations dfs_fops = {
.release = single_release,
};

+static ssize_t read_file_powercut(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ char buf[32];
+ int size = 0;
+
+ switch (powercut_info.status) {
+ case NS_POWER_CUT_DISABLED:
+ size = snprintf(buf, sizeof(buf), "disabled\n");
+ break;
+ case NS_POWER_CUT_ON_ERASE:
+ size = snprintf(buf, sizeof(buf), "on-erase:%d\n",
+ powercut_info.block);
+ break;
+ case NS_POWER_CUT_ON_PROGRAM:
+ size = snprintf(buf, sizeof(buf), "on-program:%d:%d\n",
+ powercut_info.block, powercut_info.page);
+ break;
+ default:
+ break;
+ }
+
+ return simple_read_from_buffer(user_buf, size, ppos, buf, size);
+}
+
+static ssize_t write_file_powercut(struct file *file,
+ const char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ char buf[32];
+ size_t buf_size;
+ char *ptr = buf;
+ long block = -1, page = -1;
+ int ret;
+
+ buf_size = min(count, (sizeof(buf) - 1));
+ if (copy_from_user(buf, user_buf, buf_size))
+ return -EFAULT;
+
+ buf[buf_size] = '\0';
+
+ if (!strncmp(buf, "disabled", sizeof("disabled") - 1)) {
+ powercut_info.status = NS_POWER_CUT_DISABLED;
+ } else if (!strncmp(buf, "on-erase", sizeof("on-erase") - 1)) {
+ strsep(&ptr, ":");
+ if (ptr)
+ ret = kstrtol(ptr, 0, &block);
+ powercut_info.status = NS_POWER_CUT_ON_ERASE;
+ } else if (!strncmp(buf, "on-program", sizeof("on-program") - 1)) {
+ strsep(&ptr, ":");
+ if (ptr) {
+ ret = kstrtol(ptr, 0, &block);
+ strsep(&ptr, ":");
+ if (ptr)
+ ret = kstrtol(ptr, 0, &page);
+ }
+ powercut_info.status = NS_POWER_CUT_ON_PROGRAM;
+ }
+
+ powercut_info.block = block;
+ powercut_info.page = page;
+
+ return count;
+}
+
+static const struct file_operations powercut_fops = {
+ .read = read_file_powercut,
+ .write = write_file_powercut,
+ .open = simple_open,
+ .llseek = default_llseek,
+};
+
/**
* nandsim_debugfs_create - initialize debugfs
* @dev: nandsim device description object
@@ -546,6 +638,12 @@ static int nandsim_debugfs_create(struct nandsim *dev)
goto out_remove;
dbg->dfs_wear_report = dent;

+ dent = debugfs_create_file("powercut", S_IWUSR | S_IRUSR,
+ dbg->dfs_root, dev, &powercut_fops);
+ if (IS_ERR_OR_NULL(dent))
+ goto out_remove;
+ dbg->dfs_powercut = dent;
+
return 0;

out_remove:
@@ -1206,6 +1304,10 @@ static inline void switch_to_ready_state(struct nandsim *ns, u_char status)
ns->regs.row = 0;
ns->regs.column = 0;
ns->regs.status = status;
+ if (ns->powercut) {
+ ns->powercut = false;
+ ns->regs.status |= NAND_STATUS_POWER_CUT;
+ }
}

/*
@@ -1509,29 +1611,60 @@ static void read_page(struct nandsim *ns, int num)
/*
* Erase all pages in the specified sector.
*/
-static void erase_sector(struct nandsim *ns)
+static int erase_sector(struct nandsim *ns)
{
union ns_mem *mypage;
int i;

+ if (powercut_info.status == NS_POWER_CUT_ON_ERASE) {
+ long block = ns->regs.row / ns->geom.pgsec;
+
+ if (powercut_info.block < 0 ||
+ powercut_info.block == block)
+ ns->powercut = true;
+ }
+
if (ns->cfile) {
- for (i = 0; i < ns->geom.pgsec; i++)
- if (__test_and_clear_bit(ns->regs.row + i,
- ns->pages_written)) {
- NS_DBG("erase_sector: freeing page %d\n", ns->regs.row + i);
+ for (i = 0; i < ns->geom.pgsec; i++) {
+ if (ns->powercut) {
+ loff_t pos = (loff_t)(ns->regs.row + i) *
+ ns->geom.pgszoob;
+
+ /*
+ * Corrupt all pages of the block if a
+ * power-cut occurs in the middle of a
+ * program operation.
+ */
+ prandom_bytes(ns->file_buf, ns->geom.pgszoob);
+ write_file(ns, ns->cfile, ns->file_buf,
+ ns->geom.pgszoob, pos);
+ set_bit(ns->regs.row + i, ns->pages_written);
+ NS_DBG("erase_sector (power-cut emulation): corrupting page %d\n",
+ ns->regs.row + i);
+ } else if (__test_and_clear_bit(ns->regs.row + i,
+ ns->pages_written)) {
+ NS_DBG("erase_sector: freeing page %d\n",
+ ns->regs.row + i);
}
- return;
+ }
+
+ return ns->powercut ? -1 : 0;
}

mypage = NS_GET_PAGE(ns);
for (i = 0; i < ns->geom.pgsec; i++) {
- if (mypage->byte != NULL) {
+ if (ns->powercut) {
+ if (mypage->byte)
+ prandom_bytes(mypage->byte, ns->geom.pgszoob);
+ } else if (mypage->byte != NULL) {
NS_DBG("erase_sector: freeing page %d\n", ns->regs.row+i);
kmem_cache_free(ns->nand_pages_slab, mypage->byte);
mypage->byte = NULL;
}
mypage++;
}
+
+ return ns->powercut ? -1 : 0;
}

/*
@@ -1543,6 +1676,24 @@ static int prog_page(struct nandsim *ns, int num)
union ns_mem *mypage;
u_char *pg_off;

+ if (powercut_info.status == NS_POWER_CUT_ON_PROGRAM) {
+ long block = ns->regs.row / ns->geom.pgsec;
+ long page = ns->regs.row % ns->geom.pgsec;
+
+ if (powercut_info.block < 0 ||
+ powercut_info.block == block) {
+ if (powercut_info.page < 0 ||
+ powercut_info.page == page) {
+ /*
+ * Corrupt the page if a power-cut occurs in
+ * the middle of a program operation.
+ */
+ prandom_bytes(ns->buf.byte, ns->geom.pgszoob);
+ ns->powercut = true;
+ }
+ }
+ }
+
if (ns->cfile) {
loff_t off;
ssize_t tx;
@@ -1579,7 +1730,7 @@ static int prog_page(struct nandsim *ns, int num)
return -1;
}
}
- return 0;
+ return ns->powercut ? -1 : 0;
}

mypage = NS_GET_PAGE(ns);
@@ -1603,7 +1754,7 @@ static int prog_page(struct nandsim *ns, int num)
for (i = 0; i < num; i++)
pg_off[i] &= ns->buf.byte[i];

- return 0;
+ return ns->powercut ? -1 : 0;
}

/*
@@ -1681,7 +1832,8 @@ static int do_state_action(struct nandsim *ns, uint32_t action)
ns->regs.row, NS_RAW_OFFSET(ns));
NS_LOG("erase sector %u\n", erase_block_no);

- erase_sector(ns);
+ if (erase_sector(ns) == -1)
+ return -1;

NS_MDELAY(erase_delay);

--
1.9.1


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