NAND: Enhance nandsim optionally to report wear information

A new module parameter 'rptwear' specifies how many erases between reporting wear information. Zero means never.

---
drivers/mtd/nand/nandsim.c | 98 ++++++++++++++++++++++++++++++++++++++++++++

1 files changed, 98 insertions(+), 0 deletions(-)

index 05b4207..13c5927 100644
@@ -99,6 +99,7 @@ static char *weakblocks = NULL;

static char *weakpages = NULL;
static unsigned int bitflips = 0;
static char *gravepages = NULL;
+static unsigned int rptwear = 0;

module_param(first_id_byte, uint, 0400);
module_param(second_id_byte, uint, 0400);
@@ -119,6 +120,7 @@ module_param(weakblocks, charp, 0400

module_param(weakpages,      charp, 0400);
module_param(bitflips,       uint, 0400);
module_param(gravepages,     charp, 0400);

+module_param(rptwear, uint, 0400);

MODULE_PARM_DESC(first_id_byte, "The fist byte returned by NAND Flash 'read ID' command (manufaturer ID)"); MODULE_PARM_DESC(second_id_byte, "The second byte returned by NAND Flash 'read ID' command (chip ID)");
@@ -146,6 +148,7 @@ MODULE_PARM_DESC(bitflips, "Maximu
MODULE_PARM_DESC(gravepages, "Pages that lose data [: maximum reads (defaults to 3)]"

				 " separated by commas e.g. 1401:2 means page 1401"
				 " can be read only twice before failing");

+MODULE_PARM_DESC(rptwear, "Number of erases inbetween reporting wear, if not zero");

/* The largest possible page size */
#define NS_LARGEST_PAGE_SIZE 2048
@@ -162,6 +165,8 @@ #define NS_WARN(args...) \
do { printk(KERN_WARNING NS_OUTPUT_PREFIX " warning: " args); } while(0)
#define NS_ERR(args...) \
do { printk(KERN_ERR NS_OUTPUT_PREFIX " error: " args); } while(0)
+#define NS_INFO(args...) \
+ do { printk(KERN_INFO NS_OUTPUT_PREFIX " " args); } while(0)

/* Busy-wait delay macros (microseconds, milliseconds) */ #define NS_UDELAY(us) \
@@ -394,6 +399,11 @@ struct grave_page {

static LIST_HEAD(grave_pages);

+static unsigned long *erase_block_wear = NULL;
+static unsigned int wear_eb_count = 0;
+static unsigned long total_wear = 0;
+static unsigned int rptwear_cnt = 0;
+
/* MTD structure for NAND controller */
static struct mtd_info *nsmtd;

@@ -801,6 +811,88 @@ static void free_lists(void)

		list_del(pos);
		kfree(list_entry(pos, struct grave_page, list));
	}

+ kfree(erase_block_wear);
+}
+
+static int setup_wear_reporting(struct mtd_info *mtd) +{
+ size_t mem;
+
+ if (!rptwear)
+ return 0;
+ wear_eb_count = mtd->size / mtd->erasesize;
+ mem = wear_eb_count * sizeof(unsigned long);
+ if (mem / sizeof(unsigned long) != wear_eb_count) {
+ NS_ERR("Too many erase blocks for wear reporting\n");
+ return -ENOMEM;
+ }
+ erase_block_wear = kzalloc(mem, GFP_KERNEL);
+ if (!erase_block_wear) {
+ NS_ERR("Too many erase blocks for wear reporting\n");
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+static void update_wear(unsigned int erase_block_no) +{
+ unsigned long wmin = -1, wmax = 0, avg;
+ unsigned long deciles[10], decile_max[10], tot = 0;
+ unsigned int i;
+
+ if (!erase_block_wear)
+ return;
+ total_wear += 1;
+ if (total_wear == 0)
+ NS_ERR("Erase counter total overflow\n");
+ erase_block_wear[erase_block_no] += 1;
+ if (erase_block_wear[erase_block_no] == 0)
+ NS_ERR("Erase counter overflow for erase block %u\n", erase_block_no);
+ rptwear_cnt += 1;
+ if (rptwear_cnt < rptwear)
+ return;
+ rptwear_cnt = 0;
+ /* Calc wear stats */
+ for (i = 0; i < wear_eb_count; ++i) {
+ unsigned long wear = erase_block_wear[i];
+ if (wear < wmin)
+ wmin = wear;
+ if (wear > wmax)
+ wmax = wear;
+ tot += wear;
+ }
+ for (i = 0; i < 9; ++i) {
+ deciles[i] = 0;
+ decile_max[i] = (wmax * (i + 1) + 5) / 10;
+ }
+ decile_max[9] = wmax;
+ for (i = 0; i < wear_eb_count; ++i) {
+ int d;
+ unsigned long wear = erase_block_wear[i];
+ for (d = 0; d < 10; ++d)
+ if (wear <= decile_max[d]) {
+ deciles[d] += 1;
+ break;
+ }
+ }
+ avg = tot / wear_eb_count;
+ /* Output wear report */
+ NS_INFO("*** Wear Report ***\n");
+ NS_INFO("Total numbers of erases: %lu\n", tot);
+ NS_INFO("Number of erase blocks: %u\n", wear_eb_count);
+ NS_INFO("Average number of erases: %lu\n", avg);
+ NS_INFO("Maximum number of erases: %lu\n", wmax);
+ NS_INFO("Minimum number of erases: %lu\n", wmin);
+ for (i = 0; i < 10; ++i) {
+ unsigned long from = (i ? decile_max[i - 1] + 1 : 0);
+ if (from > decile_max[i])
+ continue;
+ NS_INFO("Number of ebs with erase counts from %lu to %lu : %lu\n", + from,
+ decile_max[i],
+ deciles[i]);
+ }
+ NS_INFO("*** End of Wear Report ***\n");
}

/*
@@ -1268,6 +1360,9 @@ static int do_state_action(struct nandsi

		NS_MDELAY(erase_delay);

+ if (erase_block_wear)
+ update_wear(erase_block_no);
+

		if (erase_error(erase_block_no)) {
			NS_WARN("simulating erase failure in erase block %u\n", erase_block_no);
			return -1;
@@ -1903,6 +1998,9 @@ static int __init ns_init_module(void)
		goto error;
	}

+ if ((retval = setup_wear_reporting(nsmtd)) != 0)
+ goto err_exit;
+

	if ((retval = init_nandsim(nsmtd)) != 0)
		goto err_exit;

1.4.3

....

ID' command (manufaturer ID)");

Typo in
MODULE_PARM_DESC(first_id_byte, "The fist byte returned by NAND Flash

should read "first" not "fist"

MikeW