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UBI: support attaching by MTD character device name

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This patch adds a capability to attach MTD devices by their character
device paths. For example, one can do:

$ modprobe ubi mtd=/dev/mtd0

to attach /dev/mtd0.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy 2010-01-05 16:48:40 +02:00
parent 9e0c7ef3f6
commit f9b0080e10
1 changed files with 55 additions and 11 deletions
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66
drivers/mtd/ubi/build.c
View file

@ -37,6 +37,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/stringify.h>
#include <linux/namei.h>
#include <linux/stat.h>
#include <linux/miscdevice.h>
#include <linux/log2.h>
@ -50,7 +51,8 @@
/**
* struct mtd_dev_param - MTD device parameter description data structure.
* @name: MTD device name or number string
* @name: MTD character device node path, MTD device name, or MTD device number
* string
* @vid_hdr_offs: VID header offset
*/
struct mtd_dev_param {
@ -1116,13 +1118,50 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
}
/**
* find_mtd_device - open an MTD device by its name or number.
* @mtd_dev: name or number of the device
* open_mtd_by_chdev - open an MTD device by its character device node path.
* @mtd_dev: MTD character device node path
*
* This helper function opens an MTD device by its character node device path.
* Returns MTD device description object in case of success and a negative
* error code in case of failure.
*/
static struct mtd_info * __init open_mtd_by_chdev(const char *mtd_dev)
{
int err, major, minor, mode;
struct path path;
/* Probably this is an MTD character device node path */
err = kern_path(mtd_dev, LOOKUP_FOLLOW, &path);
if (err)
return ERR_PTR(err);
/* MTD device number is defined by the major / minor numbers */
major = imajor(path.dentry->d_inode);
minor = iminor(path.dentry->d_inode);
mode = path.dentry->d_inode->i_mode;
path_put(&path);
if (major != MTD_CHAR_MAJOR || !S_ISCHR(mode))
return ERR_PTR(-EINVAL);
if (minor & 1)
/*
* Just do not think the "/dev/mtdrX" devices support is need,
* so do not support them to avoid doing extra work.
*/
return ERR_PTR(-EINVAL);
return get_mtd_device(NULL, minor / 2);
}
/**
* open_mtd_device - open MTD device by name, character device path, or number.
* @mtd_dev: name, character device node path, or MTD device device number
*
* This function tries to open and MTD device described by @mtd_dev string,
* which is first treated as an ASCII number, and if it is not true, it is
* treated as MTD device name. Returns MTD device description object in case of
* success and a negative error code in case of failure.
* which is first treated as ASCII MTD device number, and if it is not true, it
* is treated as MTD device name, and if that is also not true, it is treated
* as MTD character device node path. Returns MTD device description object in
* case of success and a negative error code in case of failure.
*/
static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
{
@ -1137,6 +1176,9 @@ static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
* MTD device name.
*/
mtd = get_mtd_device_nm(mtd_dev);
if (IS_ERR(mtd) && PTR_ERR(mtd) == -ENODEV)
/* Probably this is an MTD character device node path */
mtd = open_mtd_by_chdev(mtd_dev);
} else
mtd = get_mtd_device(NULL, mtd_num);
@ -1352,13 +1394,15 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: "
"mtd=<name|num>[,<vid_hdr_offs>].\n"
"mtd=<name|num|path>[,<vid_hdr_offs>].\n"
"Multiple \"mtd\" parameters may be specified.\n"
"MTD devices may be specified by their number or name.\n"
"MTD devices may be specified by their number, name, or "
"path to the MTD character device node.\n"
"Optional \"vid_hdr_offs\" parameter specifies UBI VID "
"header position and data starting position to be used "
"by UBI.\n"
"Example: mtd=content,1984 mtd=4 - attach MTD device"
"header position to be used by UBI.\n"
"Example 1: mtd=/dev/mtd0 - attach MTD device "
"/dev/mtd0.\n"
"Example 2: mtd=content,1984 mtd=4 - attach MTD device "
"with name \"content\" using VID header offset 1984, and "
"MTD device number 4 with default VID header offset.");