include/linux/kdev_t.h

   1 #ifndef _LINUX_KDEV_T_H
   2 #define _LINUX_KDEV_T_H
   3 #ifdef __KERNEL__
   4 #define MINORBITS       20
   5 #define MINORMASK       ((1U << MINORBITS) - 1)
   6
   7 #define MAJOR(dev)      ((unsigned int) ((dev) >> MINORBITS))
   8 #define MINOR(dev)      ((unsigned int) ((dev) & MINORMASK))
   9 #define MKDEV(ma,mi)    (((ma) << MINORBITS) | (mi))
  10
  11 #define print_dev_t(buffer, dev)                                        \
  12         sprintf((buffer), "%u:%u\n", MAJOR(dev), MINOR(dev))
  13
  14 #define format_dev_t(buffer, dev)                                       \
  15         ({                                                              \
  16                 sprintf(buffer, "%u:%u", MAJOR(dev), MINOR(dev));       \
  17                 buffer;                                                 \
  18         })
  19
  20 /* acceptable for old filesystems */
  21 static inline int old_valid_dev(dev_t dev)
  22 {
  23         return MAJOR(dev) < 256 && MINOR(dev) < 256;
  24 }
  25
  26 static inline u16 old_encode_dev(dev_t dev)
  27 {
  28         return (MAJOR(dev) << 8) | MINOR(dev);
  29 }
  30
  31 static inline dev_t old_decode_dev(u16 val)
  32 {
  33         return MKDEV((val >> 8) & 255, val & 255);
  34 }
  35
  36 static inline int new_valid_dev(dev_t dev)
  37 {
  38         return 1;
  39 }
  40
  41 static inline u32 new_encode_dev(dev_t dev)
  42 {
  43         unsigned major = MAJOR(dev);
  44         unsigned minor = MINOR(dev);
  45         return (minor & 0xff) | (major << 8) | ((minor & ~0xff) << 12);
  46 }
  47
  48 static inline dev_t new_decode_dev(u32 dev)
  49 {
  50         unsigned major = (dev & 0xfff00) >> 8;
  51         unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
  52         return MKDEV(major, minor);
  53 }
  54
  55 static inline int huge_valid_dev(dev_t dev)
  56 {
  57         return 1;
  58 }
  59
  60 static inline u64 huge_encode_dev(dev_t dev)
  61 {
  62         return new_encode_dev(dev);
  63 }
  64
  65 static inline dev_t huge_decode_dev(u64 dev)
  66 {
  67         return new_decode_dev(dev);
  68 }
  69
  70 static inline int sysv_valid_dev(dev_t dev)
  71 {
  72         return MAJOR(dev) < (1<<14) && MINOR(dev) < (1<<18);
  73 }
  74
  75 static inline u32 sysv_encode_dev(dev_t dev)
  76 {
  77         return MINOR(dev) | (MAJOR(dev) << 18);
  78 }
  79
  80 static inline unsigned sysv_major(u32 dev)
  81 {
  82         return (dev >> 18) & 0x3fff;
  83 }
  84
  85 static inline unsigned sysv_minor(u32 dev)
  86 {
  87         return dev & 0x3ffff;
  88 }
  89
  90
  91 #else /* __KERNEL__ */
  92
  93 /*
  94 Some programs want their definitions of MAJOR and MINOR and MKDEV
  95 from the kernel sources. These must be the externally visible ones.
  96 */
  97 #define MAJOR(dev)      ((dev)>>8)
  98 #define MINOR(dev)      ((dev) & 0xff)
  99 #define MKDEV(ma,mi)    ((ma)<<8 | (mi))
 100 #endif /* __KERNEL__ */
 101 #endif