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Commit f9b0080e authored by Artem Bityutskiy's avatar Artem Bityutskiy
Browse files

UBI: support attaching by MTD character device name 



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: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
parent 9e0c7ef3

drivers/mtd/ubi/build.c

+55 −11
Original line number Diff line number Diff line
@@ -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.");