register char device and prepare mknod script

2 files changed, 32 insertions, 0 deletions

diff --git a/load.sh b/load.sh
new file mode 100755
index 0000000..41266bc
--- /dev/null
+++ b/load.sh
@@ -0,0 +1,24 @@
+#!/bin/bash
+
+MODULE=hello
+DEVICE=skull
+MODE=664
+
+# invoke insmod with all arguments and use a pathname
+# as newer modutils don't look into . by default
+/usr/bin/insmod ./${MODULE}.ko $* || exit 1
+
+# remove stale nodes
+rm -f /dev/${DEVICE}[0]
+
+MAJOR=$(awk "\$2 == \"$DEVICE\" {print \$1}" /proc/devices)
+
+mknod /dev/${DEVICE}0 c $MAJOR 0
+
+# give appriopriate permissions
+GROUP=staff
+grep -q '^staff' /etc/group || GROUP=wheel
+
+chgrp $GROUP /dev/${DEVICE}0
+chmod $MODE  /dev/${DEVICE}0
+
diff --git a/main.c b/main.c
index 6a65f3c..b6975a4 100644
--- a/main.c
+++ b/main.c
@@ -5,6 +5,7 @@
 #include <linux/string.h>
 /* used for kmalloc */
 #include <linux/slab.h>
+#include <linux/fs.h>
 
 #include <debug.h>
 
@@ -12,6 +13,8 @@ char *debugmsg = "Tesla coil is a hi freq transformer";
 struct dentry *debug_dir = NULL;
 struct dentry *debug_file = NULL;
 
+dev_t devnum;
+
 /* __init is a hint that the func is only used at initialization time, then module
  * loader drops the function after module is loaded making its memory available for other uses
  */
@@ -25,6 +28,10 @@ static int __init hello_init(void)
     printk("%s\n", msg);
     kfree(msg);
 
+    /* device numbers, major will be picked for us */
+    err = alloc_chrdev_region(&devnum, 0 /* first minor */, 1, "skull");
+    printk("major: %d, minor: %d\n", MAJOR(devnum), MINOR(devnum));
+
     /* modifies passed in ptrs */
     err = debug_init(&debug_dir, &debug_file);
     if (err)
@@ -35,6 +42,7 @@ static int __init hello_init(void)
  
 static void __exit hello_exit(void)
 {
+    unregister_chrdev_region(devnum, 1);
     debug_destroy(debug_dir, debug_file);
     printk("module named hello removed\n");
 }