mtd: expose ecc_strength through sysfs

ecc_strength element of struct mtd_info is exposed as a read-only variable in
sysfs.

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Documentation/ABI/testing/sysfs-class-mtd

@@ -123,3 +123,15 @@ Description:
 		half page, or a quarter page).
 
 		In the case of ECC NOR, it is the ECC block size.
+
+What:		/sys/class/mtd/mtdX/ecc_strength
+Date:		April 2012
+KernelVersion:	3.4
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Maximum number of bit errors that the device is capable of
+		correcting within each region covering an ecc step.  This will
+		always be a non-negative integer.  Note that some devices will
+		have multiple ecc steps within each writesize region.
+
+		In the case of devices lacking any ECC capability, it is 0.

drivers/mtd/mtdcore.c

@@ -250,6 +250,15 @@ static ssize_t mtd_name_show(struct device *dev,
 }
 static DEVICE_ATTR(name, S_IRUGO, mtd_name_show, NULL);
 
+static ssize_t mtd_ecc_strength_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", mtd->ecc_strength);
+}
+static DEVICE_ATTR(ecc_strength, S_IRUGO, mtd_ecc_strength_show, NULL);
+
 static struct attribute *mtd_attrs[] = {
 	&dev_attr_type.attr,
 	&dev_attr_flags.attr,
@@ -260,6 +269,7 @@ static struct attribute *mtd_attrs[] = {
 	&dev_attr_oobsize.attr,
 	&dev_attr_numeraseregions.attr,
 	&dev_attr_name.attr,
+	&dev_attr_ecc_strength.attr,
 	NULL,
 };