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      1 /*	$NetBSD: ping.c,v 1.5 2020/04/30 10:55:32 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2015 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(0, "$NetBSD: ping.c,v 1.5 2020/04/30 10:55:32 christos Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/conf.h>
     34 #include <sys/device.h>
     35 #include <sys/kernel.h>
     36 #include <sys/module.h>
     37 
     38 #include "ping.h"
     39 
     40 /*
     41  * Create a device /dev/ping in order to test this module.
     42  *
     43  * To use this device you need to do:
     44  *     mknod /dev/ping c 351 0
     45  *
     46  */
     47 
     48 dev_type_open(ping_open);
     49 dev_type_close(ping_close);
     50 dev_type_ioctl(ping_ioctl);
     51 
     52 static struct cdevsw ping_cdevsw = {
     53 	.d_open = ping_open,
     54 	.d_close = ping_close,
     55 	.d_read = noread,
     56 	.d_write = nowrite,
     57 	.d_ioctl = ping_ioctl,
     58 	.d_stop = nostop,
     59 	.d_tty = notty,
     60 	.d_poll = nopoll,
     61 	.d_mmap = nommap,
     62 	.d_kqfilter = nokqfilter,
     63 	.d_discard = nodiscard,
     64 	.d_flag = D_OTHER
     65 };
     66 
     67 
     68 struct ping_softc {
     69 	int		refcnt;
     70 };
     71 
     72 static struct ping_softc sc;
     73 
     74 int
     75 ping_open(dev_t self __unused, int flag __unused, int mode __unused,
     76           struct lwp *l __unused)
     77 {
     78 	if (sc.refcnt > 0)
     79 		return EBUSY;
     80 
     81 	++sc.refcnt;
     82 
     83 	return 0;
     84 }
     85 
     86 int
     87 ping_close(dev_t self __unused, int flag __unused, int mode __unused,
     88            struct lwp *l __unused)
     89 {
     90 	--sc.refcnt;
     91 
     92 	return 0;
     93 }
     94 
     95 int
     96 ping_ioctl(dev_t self __unused, u_long cmd, void *data, int flag,
     97            struct lwp *l __unused)
     98 {
     99 	switch(cmd) {
    100 	case CMD_PING:
    101 		printf("ping: pong!\n");
    102 		return 0;
    103 	default:
    104 		return ENOTTY;
    105 	}
    106 }
    107 
    108 MODULE(MODULE_CLASS_MISC, ping, NULL);
    109 
    110 static int
    111 ping_modcmd(modcmd_t cmd, void *arg __unused)
    112 {
    113 	/* The major should be verified and changed if needed to avoid
    114 	 * conflicts with other devices. */
    115 	int cmajor = 351, bmajor = -1;
    116 
    117 	switch (cmd) {
    118 	case MODULE_CMD_INIT:
    119 		if (devsw_attach("ping", NULL, &bmajor, &ping_cdevsw, &cmajor))
    120 			return ENXIO;
    121 		return 0;
    122 	case MODULE_CMD_FINI:
    123 		if (sc.refcnt > 0)
    124 			return EBUSY;
    125 
    126 		devsw_detach(NULL, &ping_cdevsw);
    127 		return 0;
    128 	default:
    129 		return ENOTTY;
    130 	}
    131 }
    132