1 files changed, 101 insertions, 0 deletions
diff --git a/include/linux/kdev_t.h b/include/linux/kdev_t.h
new file mode 100644
index 000000000000..bceea527dd37
--- /dev/null
+++ b/include/linux/kdev_t.h
@@ -0,0 +1,101 @@
+#ifndef _LINUX_KDEV_T_H
+#define _LINUX_KDEV_T_H
+#ifdef __KERNEL__
+#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;
+}
+
+
+#else /* __KERNEL__ */
+
+/*
+Some programs want their definitions of MAJOR and MINOR and MKDEV
+from the kernel sources. These must be the externally visible ones.
+*/
+#define MAJOR(dev)	((dev)>>8)
+#define MINOR(dev)	((dev) & 0xff)
+#define MKDEV(ma,mi)	((ma)<<8 | (mi))
+#endif /* __KERNEL__ */
+#endif