Patchwork [v2] MTD: expose subpage size via sysfs

mail settings
Submitter Artem Bityutskiy
Date April 17, 2009, 3:27 p.m.
Message ID <1239982072.14298.1.camel@localhost.localdomain>
Download mbox | patch
Permalink /patch/26126/
State New, archived
Headers show


Artem Bityutskiy - April 17, 2009, 3:27 p.m.
And the same patch with a better commit message.

From: Artem Bityutskiy <>
Subject: [PATCH v2] MTD: expose subpage size via sysfs

MTD has got sysfs support in 2.6.30-rc1. But subpage size is not
exposed there - do this.

UBI utilities badly need this parameter. At the moment there is
no way to get subpage size - ioctls do not return it. And we
just got sysfs support, so we can easilly extend it with this
additional parameter.

This can be merged late in the development cycle because:
1. sysfs support has been just added - there are no users for
   it so far, even.
2. UBI utilities really need this parameter, and it is better
   not to delay this.

Signed-off-by: Artem Bityutskiy <>
 drivers/mtd/mtdcore.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)


diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index fdd6ae8..ae6f15e 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -132,6 +132,17 @@  static ssize_t mtd_writesize_show(struct device *dev,
 static DEVICE_ATTR(writesize, S_IRUGO, mtd_writesize_show, NULL);
+static ssize_t mtd_subpage_size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+	struct mtd_info *mtd = dev_to_mtd(dev);
+	unsigned int subpage_size = mtd->writesize >> mtd->subpage_sft;
+	return snprintf(buf, PAGE_SIZE, "%u\n", subpage_size);
+static DEVICE_ATTR(subpage_size, S_IRUGO, mtd_subpage_size_show, NULL);
 static ssize_t mtd_oobsize_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -169,6 +180,7 @@  static struct attribute *mtd_attrs[] = {
+	&dev_attr_subpage_size.attr,