mtd: Add sysfs attribute for mtd OOB available size

Expose mtd OOB available size by sysfs file. Then users can get available
OOB size by accessing /sys/class/mtd/mtdX/oobavail.

Signed-off-by: Xiaolei Li <xiaolei.li@mediatek.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

diff --git a/Documentation/ABI/testing/sysfs-class-mtd b/Documentation/ABI/testing/sysfs-class-mtd
index f34e592301d1dbd9190d8557e43fd05bcde08f80..3bc7c0a95c927896fdee10193108ba802d45c2e3 100644 (file)
--- a/Documentation/ABI/testing/sysfs-class-mtd
+++ b/Documentation/ABI/testing/sysfs-class-mtd
@@ -232,3 +232,11 @@ Description:
                of the parent (another partition or a flash device) in bytes.
                This attribute is absent on flash devices, so it can be used
                to distinguish them from partitions.
+
+What:          /sys/class/mtd/mtdX/oobavail
+Date:          April 2018
+KernelVersion: 4.16
+Contact:       linux-mtd@lists.infradead.org
+Description:
+               Number of bytes available for a client to place data into
+               the out of band area.

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 807d17d863b3e9736c51c920f8e7456fe8e7ec17..adf18b0d22b599dc3f40d39d71107ca13f9595f2 100644 (file)
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -210,6 +210,15 @@ static ssize_t mtd_oobsize_show(struct device *dev,
 }
 static DEVICE_ATTR(oobsize, S_IRUGO, mtd_oobsize_show, NULL);
 
+static ssize_t mtd_oobavail_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->oobavail);
+}
+static DEVICE_ATTR(oobavail, S_IRUGO, mtd_oobavail_show, NULL);
+
 static ssize_t mtd_numeraseregions_show(struct device *dev,
                struct device_attribute *attr, char *buf)
 {
@@ -327,6 +336,7 @@ static struct attribute *mtd_attrs[] = {
        &dev_attr_writesize.attr,
        &dev_attr_subpagesize.attr,
        &dev_attr_oobsize.attr,
+       &dev_attr_oobavail.attr,
        &dev_attr_numeraseregions.attr,
        &dev_attr_name.attr,
        &dev_attr_ecc_strength.attr,