kdev_t.h

Go to the documentation of this file.

#ifndef _LINUX_KDEV_T_H
#define _LINUX_KDEV_T_H

#include <uapi/linux/kdev_t.h>

#define MINORBITS   20
#define MINORMASK   ((1U << MINORBITS) - 1)

#define MAJOR(dev)  ((unsigned int) ((dev) >> MINORBITS))
#define MINOR(dev)  ((unsigned int) ((dev) & MINORMASK))
#define MKDEV(ma,mi)    (((ma) << MINORBITS) | (mi))

#define print_dev_t(buffer, dev)                    \
    sprintf((buffer), "%u:%u\n", MAJOR(dev), MINOR(dev))

#define format_dev_t(buffer, dev)                   \
    ({                              \
        sprintf(buffer, "%u:%u", MAJOR(dev), MINOR(dev));   \
        buffer;                         \
    })

/* acceptable for old filesystems */
static inline int old_valid_dev(dev_t dev)
{
    return MAJOR(dev) < 256 && MINOR(dev) < 256;
}

static inline u16 old_encode_dev(dev_t dev)
{
    return (MAJOR(dev) << 8) | MINOR(dev);
}

static inline dev_t old_decode_dev(u16 val)
{
    return MKDEV((val >> 8) & 255, val & 255);
}

static inline int new_valid_dev(dev_t dev)
{
    return 1;
}

static inline u32 new_encode_dev(dev_t dev)
{
    unsigned major = MAJOR(dev);
    unsigned minor = MINOR(dev);
    return (minor & 0xff) | (major << 8) | ((minor & ~0xff) << 12);
}

static inline dev_t new_decode_dev(u32 dev)
{
    unsigned major = (dev & 0xfff00) >> 8;
    unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
    return MKDEV(major, minor);
}

static inline int huge_valid_dev(dev_t dev)
{
    return 1;
}

static inline u64 huge_encode_dev(dev_t dev)
{
    return new_encode_dev(dev);
}

static inline dev_t huge_decode_dev(u64 dev)
{
    return new_decode_dev(dev);
}

static inline int sysv_valid_dev(dev_t dev)
{
    return MAJOR(dev) < (1<<14) && MINOR(dev) < (1<<18);
}

static inline u32 sysv_encode_dev(dev_t dev)
{
    return MINOR(dev) | (MAJOR(dev) << 18);
}

static inline unsigned sysv_major(u32 dev)
{
    return (dev >> 18) & 0x3fff;
}

static inline unsigned sysv_minor(u32 dev)
{
    return dev & 0x3ffff;
}

#endif