Index: sys/sys/devio.h
===================================================================
RCS file: sys/sys/devio.h
diff -N sys/sys/devio.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ sys/sys/devio.h	27 Mar 2008 05:39:06 -0000
@@ -0,0 +1,19 @@
+#ifndef _SYS_DEVIO_H
+#define _SYS_DEVIO_H
+
+#ifndef _KERNEL
+#include <sys/types.h>
+#endif
+#include <sys/ioccom.h>
+
+#define MAXDEVNAME	32
+struct device_ioctl
+{
+	char	dio_devclass[MAXDEVNAME];
+	int	dio_unit;
+};
+
+#define	DEVIOC_SUSPEND	_IOW('d', 1, struct device_ioctl)
+#define	DEVIOC_RESUME	_IOW('d', 2, struct device_ioctl)
+
+#endif /* _SYS_DEVIO_H */
Index: sys/kern/subr_bus.c
===================================================================
RCS file: /cache/ncvs/src/sys/kern/subr_bus.c,v
retrieving revision 1.207
diff -u -r1.207 subr_bus.c
--- sys/kern/subr_bus.c	20 Mar 2008 21:24:32 -0000	1.207
+++ sys/kern/subr_bus.c	27 Mar 2008 06:26:12 -0000
@@ -31,6 +31,7 @@
 
 #include <sys/param.h>
 #include <sys/conf.h>
+#include <sys/devio.h>
 #include <sys/filio.h>
 #include <sys/lock.h>
 #include <sys/kernel.h>
@@ -403,8 +404,10 @@
 static int
 devopen(struct cdev *dev, int oflags, int devtype, d_thread_t *td)
 {
+#if 0
 	if (devsoftc.inuse)
 		return (EBUSY);
+#endif
 	/* move to init */
 	devsoftc.inuse = 1;
 	devsoftc.nonblock = 0;
@@ -479,6 +482,26 @@
 			devsoftc.async_proc = NULL;
 		return (0);
 
+	case DEVIOC_SUSPEND:
+	case DEVIOC_RESUME:
+	{
+		devclass_t dc;
+		device_t dev;
+		struct device_ioctl *dio = (struct device_ioctl *)data;
+		int err;
+
+		dc = devclass_find(dio->dio_devclass);
+		if (dc == NULL)
+			return (ENXIO);
+		dev = devclass_get_device(dc, dio->dio_unit);
+		if (dev == NULL)
+			return (ENXIO);
+		if (cmd == DEVIOC_SUSPEND)
+			err = DEVICE_SUSPEND(dev);
+		else
+			err = DEVICE_RESUME(dev);
+		return (err);
+	}
 		/* (un)Support for other fcntl() calls. */
 	case FIOCLEX:
 	case FIONCLEX:
Index: usr.bin/devctl/Makefile
===================================================================
RCS file: usr.bin/devctl/Makefile
diff -N usr.bin/devctl/Makefile
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ usr.bin/devctl/Makefile	27 Mar 2008 06:52:22 -0000
@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+PROG=	devctl
+
+.include <bsd.prog.mk>
Index: usr.bin/devctl/devctl.1
===================================================================
RCS file: usr.bin/devctl/devctl.1
diff -N usr.bin/devctl/devctl.1
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ usr.bin/devctl/devctl.1	27 Mar 2008 06:55:09 -0000
@@ -0,0 +1,40 @@
+.\"
+.\" Copyright (c) 2008 M. Warner Losh.
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD: src/sbin/devd/devd.8,v 1.17 2006/09/17 22:49:26 ru Exp $
+.\"
+.Dd March 27, 2008
+.Dt devctl 1
+.Os
+.Sh NAME
+.Nm devctl
+.Nd "device state change utility"
+.Sh SYNOPSIS
+.Nm
+.Op Fl rs
+.Sh DESCRIPTION
+The
+.Nm
+utility suspends and resumes devices.
Index: usr.bin/devctl/devctl.c
===================================================================
RCS file: usr.bin/devctl/devctl.c
diff -N usr.bin/devctl/devctl.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ usr.bin/devctl/devctl.c	27 Mar 2008 06:01:11 -0000
@@ -0,0 +1,54 @@
+#include <err.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/devio.h>
+
+void
+usage()
+{
+	fprintf(stderr, "devctl [-r] [-s] devname devunit\n");
+	exit(1);
+}
+
+int
+main(int argc, char **argv)
+{
+	int ch, fd;
+	int rflag = 0;
+	int sflag = 0;
+	struct device_ioctl dio;
+
+	while ((ch = getopt(argc, argv, "rs")) != -1) {
+		switch (ch) {
+		case 'r':
+			rflag++;
+			break;
+		case 's':
+			sflag++;
+			break;
+		default:
+			usage();
+		}
+	}
+	if (rflag + sflag != 1)
+		errx(1, "You must specify exactly one of -r and -s");
+	argv += optind;
+	argc -= optind;
+	if (argc < 2)
+		usage();
+	fd = open("/dev/devctl", O_RDWR);
+	if (fd == -1)
+		err(1, "Opening /dev/devctl");
+	strcpy(dio.dio_devclass, argv[0]);
+	dio.dio_unit = strtol(argv[1], NULL, 0);
+	if (rflag) {
+		if (ioctl(fd, DEVIOC_RESUME, &dio) == -1)
+			err(1, "DEVIOC_RESUME");
+	} else {
+		if (ioctl(fd, DEVIOC_SUSPEND, &dio) == -1)
+			err(1, "DEVIOC_RESUME");
+	}
+}