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mtd: part: Add sysfs variable for offset of partition

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This patch makes a sysfs variable called 'offset' on each partition
which contains the offset in bytes from the beginning of the master
device that the partition starts.

Signed-off-by: Dan Ehrenberg <dehrenberg@chromium.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Dan Ehrenberg 2015-04-02 15:15:11 -07:00 committed by Brian Norris
parent 727dc612c4
commit a62c24d755
2 changed files with 39 additions and 0 deletions
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10
Documentation/ABI/testing/sysfs-class-mtd
View file

@ -222,3 +222,13 @@ Description:
The number of blocks that are marked as reserved, if any, in
this partition. These are typically used to store the in-flash
bad block table (BBT).
What: /sys/class/mtd/mtdX/offset
Date: March 2015
KernelVersion: 4.1
Contact: linux-mtd@lists.infradead.org
Description:
For a partition, the offset of that partition from the start
of the master device in bytes. This attribute is absent on
main devices, so it can be used to distinguish between
partitions and devices that aren't partitions.

29
drivers/mtd/mtdpart.c
View file

@ -554,6 +554,30 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
return slave;
}
static ssize_t mtd_partition_offset_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct mtd_info *mtd = dev_get_drvdata(dev);
struct mtd_part *part = PART(mtd);
return snprintf(buf, PAGE_SIZE, "%lld\n", part->offset);
}
static DEVICE_ATTR(offset, S_IRUGO, mtd_partition_offset_show, NULL);
static const struct attribute *mtd_partition_attrs[] = {
&dev_attr_offset.attr,
NULL
};
static int mtd_add_partition_attrs(struct mtd_part *new)
{
int ret = sysfs_create_files(&new->mtd.dev.kobj, mtd_partition_attrs);
if (ret)
printk(KERN_WARNING
"mtd: failed to create partition attrs, err=%d\n", ret);
return ret;
}
int mtd_add_partition(struct mtd_info *master, const char *name,
long long offset, long long length)
{
@ -603,6 +627,8 @@ int mtd_add_partition(struct mtd_info *master, const char *name,
add_mtd_device(&new->mtd);
mtd_add_partition_attrs(new);
return ret;
err_inv:
mutex_unlock(&mtd_partitions_mutex);
@ -620,6 +646,8 @@ int mtd_del_partition(struct mtd_info *master, int partno)
list_for_each_entry_safe(slave, next, &mtd_partitions, list)
if ((slave->master == master) &&
(slave->mtd.index == partno)) {
sysfs_remove_files(&slave->mtd.dev.kobj,
mtd_partition_attrs);
ret = del_mtd_device(&slave->mtd);
if (ret < 0)
break;
@ -663,6 +691,7 @@ int add_mtd_partitions(struct mtd_info *master,
mutex_unlock(&mtd_partitions_mutex);
add_mtd_device(&slave->mtd);
mtd_add_partition_attrs(slave);
cur_offset = slave->offset + slave->mtd.size;
}