LXR linux/include/linux/kdev

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_KDEV_T_H
   3#define _LINUX_KDEV_T_H
   4
   5#include <uapi/linux/kdev_t.h>
   6
   7#define MINORBITS       20
   8#define MINORMASK       ((1U << MINORBITS) - 1)
   9
  10#define MAJOR(dev)      ((unsigned int) ((dev) >> MINORBITS))
  11#define MINOR(dev)      ((unsigned int) ((dev) & MINORMASK))
  12#define MKDEV(ma,mi)    (((ma) << MINORBITS) | (mi))
  13
  14#define print_dev_t(buffer, dev)                                        \
  15        sprintf((buffer), "%u:%u\n", MAJOR(dev), MINOR(dev))
  16
  17#define format_dev_t(buffer, dev)                                       \
  18        ({                                                              \
  19                sprintf(buffer, "%u:%u", MAJOR(dev), MINOR(dev));       \
  20                buffer;                                                 \
  21        })
  22
  23/* acceptable for old filesystems */
  24static inline bool old_valid_dev(dev_t dev)
  25{
  26        return MAJOR(dev) < 256 && MINOR(dev) < 256;
  27}
  28
  29static inline u16 old_encode_dev(dev_t dev)
  30{
  31        return (MAJOR(dev) << 8) | MINOR(dev);
  32}
  33
  34static inline dev_t old_decode_dev(u16 val)
  35{
  36        return MKDEV((val >> 8) & 255, val & 255);
  37}
  38
  39static inline u32 new_encode_dev(dev_t dev)
  40{
  41        unsigned major = MAJOR(dev);
  42        unsigned minor = MINOR(dev);
  43        return (minor & 0xff) | (major << 8) | ((minor & ~0xff) << 12);
  44}
  45
  46static inline dev_t new_decode_dev(u32 dev)
  47{
  48        unsigned major = (dev & 0xfff00) >> 8;
  49        unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
  50        return MKDEV(major, minor);
  51}
  52
  53static inline u64 huge_encode_dev(dev_t dev)
  54{
  55        return new_encode_dev(dev);
  56}
  57
  58static inline dev_t huge_decode_dev(u64 dev)
  59{
  60        return new_decode_dev(dev);
  61}
  62
  63static inline int sysv_valid_dev(dev_t dev)
  64{
  65        return MAJOR(dev) < (1<<14) && MINOR(dev) < (1<<18);
  66}
  67
  68static inline u32 sysv_encode_dev(dev_t dev)
  69{
  70        return MINOR(dev) | (MAJOR(dev) << 18);
  71}
  72
  73static inline unsigned sysv_major(u32 dev)
  74{
  75        return (dev >> 18) & 0x3fff;
  76}
  77
  78static inline unsigned sysv_minor(u32 dev)
  79{
  80        return dev & 0x3ffff;
  81}
  82
  83#endif
  84