xref: /freebsd/share/examples/modules/skel.c (revision 0044e9124e474b5d45a77df328d0d7b00ec7e57b)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2023 George V. Neville-Neil
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  *
27  */
28 
29 /*
30  * SKEL Loadable Kernel Module for the FreeBSD Operating System
31  *
32  * The SKEL module is meant to act as a skeleton for creating new
33  * kernel modules.
34  *
35  * This module can be loaded and unloaded from * FreeBSD and is for
36  * use in teaching as well.
37  *
38  */
39 
40 #include <sys/param.h>
41 #include <sys/kernel.h>
42 #include <sys/systm.h>
43 #include <sys/module.h>
44 
45 /*
46  * Every module can have a module specific piece of code that is
47  * executed whenever the module is loaded or unloaded.  The following
48  * is a trivial example that prints a message on the console whenever
49  * the module is loaded or unloaded.
50  */
51 
52 static int
skel_mod_event(module_t mod,int type,void * data)53 skel_mod_event(module_t mod, int type, void *data)
54 {
55 
56 	switch (type) {
57 	case MOD_LOAD:
58 		printf("SKEL module loading.\n");
59 		return (0);
60 	case MOD_UNLOAD:
61 		printf("SKEL module unloading.\n");
62 		return (0);
63 	}
64 	return (EOPNOTSUPP);
65 }
66 
67 /*
68  * Modules can have associated data and the module data also contains
69  * an entry for the function called by the kernel on load and unload.
70  */
71 
72 static moduledata_t skel_mod = {
73 	"skel",
74 	skel_mod_event,
75 	NULL,
76 };
77 
78 /*
79  * Each module is declared with its name and module data.  The
80  * ordering arguments at the end put this module into the device
81  * driver class, which is sufficient for our needs.  The complete list
82  * of modules types and ording can be found in sys/kernel.h
83  */
84 
85 DECLARE_MODULE(skel, skel_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
86 
87