1 files changed, 49 insertions, 0 deletions
diff --git a/kernel/include/drivers/dev.h b/kernel/include/drivers/dev.h
new file mode 100644
index 0000000..883dcba
--- /dev/null
+++ b/kernel/include/drivers/dev.h
@@ -0,0 +1,49 @@
+#pragma once
+
+#include "types.h"
+
+/*
+ * A Weenix "device identifier" is the concatenation of:
+ *     - a "driver number" or "device type" (major number)
+ *     - a "device number" (minor number)
+ *
+ * The device identifiers for block devices and character devices are
+ * independent. That is, you could have both a block device and a char device
+ * with major 3, minor 5 (for example). They would be distinct.
+ *
+ * Weenix's device number allocation/assignment scheme is as follows:
+ *
+ *     - major 0 (byte or block), minor 0: reserved as an analogue of NULL
+ *       for device id's
+ *
+ *     - char major 1:         Memory devices (mem)
+ *         - minor 0:          /dev/null       The null device
+ *         - minor 1:          /dev/zero       The zero device
+ *
+ *     - char major 2:         TTY devices (tty)
+ *         - minor 0:          /dev/tty0       First TTY device
+ *         - minor 1:          /dev/tty1       Second TTY device
+ *         - and so on...
+ *
+ *     - block major 1:        Disk devices
+ *         - minor 0:          first disk device
+ *         - minor 1:          second disk device
+ *         - and so on...
+ */
+
+#define MINOR_BITS 8
+#define MINOR_MASK ((1U << MINOR_BITS) - 1)
+#define MAJOR(devid) ((unsigned)((devid) >> MINOR_BITS))
+#define MINOR(devid) ((unsigned)((devid)&MINOR_MASK))
+#define MKDEVID(major, minor) ((devid_t)(((major) << MINOR_BITS) | (minor)))
+
+/* convenience definition: the NULL device id: */
+#define NULL_DEVID (MKDEVID(0, 0))
+#define MEM_NULL_DEVID (MKDEVID(1, 0))
+#define MEM_ZERO_DEVID (MKDEVID(1, 1))
+
+#define DISK_MAJOR 1
+
+#define MEM_MAJOR 1
+#define MEM_NULL_MINOR 0
+#define MEM_ZERO_MINOR 1