Patchwork [v3] MTD: expose subpage size via sysfs

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Submitter Artem Bityutskiy
Date April 18, 2009, 9:29 a.m.
Message ID <1240046982.14298.3.camel@localhost.localdomain>
Download mbox | patch
Permalink /patch/26158/
State Accepted
Commit e7693548950ea5801d5d8b00414aed37033cf972
Headers show


Artem Bityutskiy - April 18, 2009, 9:29 a.m.
And yet another version. Make subpage file name "subpagesize",
not "subpage_size", just for consistency, because we already
have "erasesize" and "writesize" files.

From: Artem Bityutskiy <>
Subject: [PATCH v3] 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..68e3846 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_subpagesize_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+	struct mtd_info *mtd = dev_to_mtd(dev);
+	unsigned int subpagesize = mtd->writesize >> mtd->subpage_sft;
+	return snprintf(buf, PAGE_SIZE, "%u\n", subpagesize);
+static DEVICE_ATTR(subpagesize, S_IRUGO, mtd_subpagesize_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_subpagesize.attr,