#ifndef _LINUX_KDEV_T_H
#define _LINUX_KDEV_T_H
#ifdef __KERNEL__
-/*
-As a preparation for the introduction of larger device numbers,
-we introduce a type kdev_t to hold them. No information about
-this type is known outside of this include file.
-
-Objects of type kdev_t designate a device. Outside of the kernel
-the corresponding things are objects of type dev_t - usually an
-integral type with the device major and minor in the high and low
-bits, respectively. Conversion is done by
-
-extern kdev_t to_kdev_t(int);
-
-It is up to the various file systems to decide how objects of type
-dev_t are stored on disk.
-The only other point of contact between kernel and outside world
-are the system calls stat and mknod, new versions of which will
-eventually have to be used in libc.
-
-[Unfortunately, the floppy control ioctls fail to hide the internal
-kernel structures, and the fd_device field of a struct floppy_drive_struct
-is user-visible. So, it remains a dev_t for the moment, with some ugly
-conversions in floppy.c.]
-
-Inside the kernel, we aim for a kdev_t type that is a pointer
-to a structure with information about the device (like major,
-minor, size, blocksize, sectorsize, name, read-only flag,
-struct file_operations etc.).
-
-However, for the time being we let kdev_t be almost the same as dev_t:
-
-typedef struct { unsigned short major, minor; } kdev_t;
-
-Admissible operations on an object of type kdev_t:
-- passing it along
-- comparing it for equality with another such object
-- storing it in inode->i_rdev or tty->device
-- using its bit pattern as argument in a hash function
-- finding its major and minor
-- complaining about it
-
-An object of type kdev_t is created only by the function MKDEV(),
-with the single exception of the constant 0 (no device).
-
-Right now the other information mentioned above is usually found
-in static arrays indexed by major or major,minor.
-
-An obstacle to immediately using
- typedef struct { ... (* lots of information *) } *kdev_t
-is the case of mknod used to create a block device that the
-kernel doesn't know about at present (but first learns about
-when some module is inserted).
-
-aeb - 950811
-*/
-
-
-/*
- * NOTE NOTE NOTE!
- *
- * The kernel-internal "kdev_t" will eventually have
- * 20 bits for minor numbers, and 12 bits for majors.
- *
- * HOWEVER, the external representation is still 8+8
- * bits, and there is no way to generate the extended
- * "kdev_t" format yet. Which is just as well, since
- * we still use "minor" as an index into various
- * static arrays, and they are sized for a 8-bit index.
- */
-typedef struct {
- unsigned short value;
-} kdev_t;
-
-#define KDEV_MINOR_BITS 8
-#define KDEV_MAJOR_BITS 8
-
-#define __mkdev(major,minor) (((major) << KDEV_MINOR_BITS) + (minor))
-
-#define mk_kdev(major, minor) ((kdev_t) { __mkdev(major,minor) } )
-
-#define NODEV (mk_kdev(0,0))
-
-/* Mask off the high bits for now.. */
-#define minor(dev) ((dev).value & 0xff)
-#define major(dev) (((dev).value >> KDEV_MINOR_BITS) & 0xff)
-
/* These are for user-level "dev_t" */
#define MINORBITS 8
#define MINORMASK ((1U << MINORBITS) - 1)
#define MINOR(dev) ((unsigned int) ((dev) & MINORMASK))
#define MKDEV(ma,mi) (((ma) << MINORBITS) | (mi))
-/*
- * Conversion functions
- */
-
-static inline int kdev_t_to_nr(kdev_t dev)
-{
- return MKDEV(major(dev), minor(dev));
-}
-
-static inline kdev_t to_kdev_t(int dev)
-{
- return mk_kdev(MAJOR(dev),MINOR(dev));
-}
-
#define print_dev_t(buffer, dev) \
sprintf((buffer), "%u:%u\n", MAJOR(dev), MINOR(dev))
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