MFC 278320,278336,278830,285621:

Add devctl(8): a utility for manipulating new-bus devices.  Note that
this version does not include the 'suspend' and 'resume' commands
present in HEAD as those depend on larger changes to the suspend and
resume code in the kernel.

278320:
Add a new device control utility for new-bus devices called devctl.  This
allows the user to request administrative changes to individual devices
such as attach or detaching drivers or disabling and re-enabling devices.
- Add a new /dev/devctl2 character device which uses ioctls for device
  requests.  The ioctls use a common 'struct devreq' which is somewhat
  similar to 'struct ifreq'.
- The ioctls identify the device to operate on via a string.  This
  string can either by the device's name, or it can be a bus-specific
  address.  (For unattached devices, a bus address is the only way to
  locate a device.)  Bus drivers register an eventhandler to claim
  unrecognized device names that the driver recognizes as a valid address.
  Two buses currently support addresses: ACPI recognizes any device
  in the ACPI namespace via its full path starting with "\" and
  the PCI bus driver recognizes an address specification of
  'pci[<domain>:]<bus>:<slot>:<func>' (identical to the PCI selector
  strings supported by pciconf).
- To make it easier to cut and paste, change the PnP location string
  in the PCI bus driver to output a full PCI selector string rather
  than 'slot=<slot> function=<func>'.
- Add a devctl(3) interface in libdevctl which provides a wrapper around
  the ioctls and is the preferred interface for other userland code.
- Add a devctl(8) program which is a simple wrapper around the requests
  supported by devctl(3).
- Add a resource_unset_value() function that can be used to remove a
  hint from the kernel environment.  This is used to clear a
  hint.<driver>.<unit>.disabled hint when re-enabling a boot-time
  disabled device.

278336:
Unbreak the build (memchr is explicitly required by devctl(9) after r278320)

278830:
install the man page...

285621:
Fix formatting.

Approved by:	re (marius)

17 files changed, 1199 insertions, 5 deletions

diff --git a/contrib/mdocml/lib.in b/contrib/mdocml/lib.in
index 0e3162f..76bd313 100644
--- a/contrib/mdocml/lib.in
+++ b/contrib/mdocml/lib.in
@@ -37,6 +37,7 @@ LINE("libcipher",	"FreeSec Crypt Library (libcipher, \\-lcipher)")
 LINE("libcompat",	"Compatibility Library (libcompat, \\-lcompat)")
 LINE("libcrypt",	"Crypt Library (libcrypt, \\-lcrypt)")
 LINE("libcurses",	"Curses Library (libcurses, \\-lcurses)")
+LINE("libdevctl",	"Device Control Library (libdevctl, \\-ldevctl)")
 LINE("libdevinfo",	"Device and Resource Information Utility Library (libdevinfo, \\-ldevinfo)")
 LINE("libdevstat",	"Device Statistics Library (libdevstat, \\-ldevstat)")
 LINE("libdisk",		"Interface to Slice and Partition Labels Library (libdisk, \\-ldisk)")
diff --git a/lib/Makefile b/lib/Makefile
index 742bd5e..d2cda1e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -37,6 +37,7 @@ SUBDIR=	${SUBDIR_ORDERED} \
 	${_libcom_err} \
 	libcompat \
 	libcrypt \
+	libdevctl \
 	libdevinfo \
 	libdevstat \
 	libdpv \
diff --git a/lib/libdevctl/Makefile b/lib/libdevctl/Makefile
new file mode 100644
index 0000000..74687ec
--- /dev/null
+++ b/lib/libdevctl/Makefile
@@ -0,0 +1,8 @@
+# $FreeBSD$
+
+LIB=	devctl
+SRCS=	devctl.c
+INCS=	devctl.h
+MAN=	devctl.3
+
+.include <bsd.lib.mk>
diff --git a/lib/libdevctl/devctl.3 b/lib/libdevctl/devctl.3
new file mode 100644
index 0000000..b8a84d4
--- /dev/null
+++ b/lib/libdevctl/devctl.3
@@ -0,0 +1,254 @@
+.\"
+.\" Copyright (c) 2014 John Baldwin <jhb@FreeBSD.org>
+.\" 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.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd December 26, 2014
+.Dt DEVCTL 3
+.Os
+.Sh NAME
+.Nm devctl ,
+.Nm devctl_attach ,
+.Nm devctl_detach ,
+.Nm devctl_disable ,
+.Nm devctl_enable
+.Nd device control library
+.Sh LIBRARY
+.Lb libdevctl
+.Sh SYNOPSIS
+.In devctl.h
+.Ft int
+.Fn devctl_attach "const char *device"
+.Ft int
+.Fn devctl_detach "const char *device" "bool force"
+.Ft int
+.Fn devctl_disable "const char *device" "bool force_detach"
+.Ft int
+.Fn devctl_enable "const char *device"
+.Ft int
+.Fn devctl_set_driver "const char *device" "const char *driver" "bool force"
+.Sh DESCRIPTION
+The
+.Nm
+library adjusts the state of devices in the kernel's internal device
+hierarchy.
+Each control operation accepts a
+.Fa device
+argument that identifies the device to adjust.
+The
+.Fa device
+may be specified as either the name of an existing device or as a
+bus-specific address.
+The following bus-specific address formats are currently supported:
+.Bl -tag -offset indent
+.It Sy pci Ns Fa domain Ns : Ns Fa bus Ns : Ns Fa slot Ns : Ns Fa function
+A PCI device with the specified
+.Fa domain ,
+.Fa bus ,
+.Fa slot ,
+and
+.Fa function .
+.It Sy pci Ns Fa bus Ns : Ns Fa slot Ns : Ns Fa function
+A PCI device in domain zero with the specified
+.Fa bus ,
+.Fa slot ,
+and
+.Fa function .
+.It Fa handle
+A device with an ACPI handle of
+.Fa handle .
+The handle must be specified as an absolute path and must begin with a
+.Dq \e .
+.El
+.Pp
+The
+.Fn devctl_attach
+function probes a device and attaches a suitable device driver if one is
+found.
+.Pp
+The
+.Fn devctl_detach
+function detaches a device from its current device driver.
+The device is left detached until either a new driver for its parent
+bus is loaded or the device is explicitly probed via
+.Fn devctl_attach .
+If
+.Fa force
+is true,
+the current device driver will be detached even if the device is busy.
+.Pp
+The
+.Fn devctl_disable
+function disables a device.
+If the device is currently attached to a device driver,
+the device driver will be detached from the device,
+but the device will retain its current name.
+If
+.Fa force_detach
+is true,
+the current device driver will be detached even if the device is busy.
+The device will remain disabled and detached until it is explicitly enabled
+via
+.Fn devctl_enable .
+.Pp
+The
+.Fn devctl_enable
+function re-enables a disabled device.
+The device will probe and attach if a suitable device driver is found.
+.Pp
+The
+.Fn devctl_set_driver
+function attaches a device driver named
+.Fa driver
+to a device.
+If the device is already attached and
+.Fa force
+is false,
+the request will fail.
+If the device is already attached and
+.Fa force
+is true,
+the device will be detached from its current device driver before it is
+attached to the new device driver.
+.Sh RETURN VALUES
+.Rv -std devctl_attach devctl_detach devctl_disable devctl_enable \
+devctl_set_driver
+.Sh ERRORS
+In addition to specific errors noted below,
+all of the
+.Nm
+functions may fail for any of the errors described in
+.Xr open 2
+as well as:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The device name is too long.
+.It Bq Er ENOENT
+No existing device matches the specified name or location.
+.It Bq Er EPERM
+The current process is not permitted to adjust the state of
+.Fa device .
+.El
+.Pp
+The
+.Fn devctl_attach
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er EBUSY
+The device is already attached.
+.It Bq Er ENOMEM
+An internal memory allocation request failed.
+.It Bq Er ENXIO
+The device is disabled.
+.It Bq Er ENXIO
+No suitable driver for the device could be found,
+or the driver failed to attach.
+.El
+.Pp
+The
+.Fn devctl_detach
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er EBUSY
+The current device driver for
+.Fa device
+is busy and cannot detach at this time.
+Note that some drivers may return this even if
+.Fa force
+is true.
+.It Bq Er ENXIO
+The device is not attached to a driver.
+.It Bq Er ENXIO
+The current device driver for
+.Fa device
+does not support detaching.
+.El
+.Pp
+The
+.Fn devctl_enable
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er EBUSY
+The device is already enabled.
+.It Bq Er ENOMEM
+An internal memory allocation request failed.
+.It Bq Er ENXIO
+No suitable driver for the device could be found,
+or the driver failed to attach.
+.El
+.Pp
+The
+.Fn devctl_disable
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er EBUSY
+The current device driver for
+.Fa device
+is busy and cannot detach at this time.
+Note that some drivers may return this even if
+.Fa force_detach
+is true.
+.It Bq Er ENXIO
+The device is already disabled.
+.It Bq Er ENXIO
+The current device driver for
+.Fa device
+does not support detaching.
+.El
+.Pp
+The
+.Fn devctl_set_driver
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er EBUSY
+The device is currently attached to a device driver and
+.Fa force
+is false.
+.It Bq Er EBUSY
+The current device driver for
+.Fa device
+is busy and cannot detach at this time.
+.It Bq Er EFAULT
+The
+.Fa driver
+argument points outside the process' allocated address space.
+.It Bq Er ENOENT
+No device driver with the requested name exists.
+.It Bq Er ENOMEM
+An internal memory allocation request failed.
+.It Bq Er ENXIO
+The device is disabled.
+.It Bq Er ENXIO
+The new device driver failed to attach.
+.El
+.Sh SEE ALSO
+.Xr devinfo 3 ,
+.Xr devstat 3 ,
+.Xr devctl 8
+.Sh HISTORY
+The
+.Nm
+library first appeared in
+.Fx 11.0 .
diff --git a/lib/libdevctl/devctl.c b/lib/libdevctl/devctl.c
new file mode 100644
index 0000000..fa0e6a5
--- /dev/null
+++ b/lib/libdevctl/devctl.c
@@ -0,0 +1,110 @@
+/*-
+ * Copyright (c) 2014 John Baldwin <jhb@FreeBSD.org>
+ * 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/bus.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include "devctl.h"
+
+static int
+devctl_request(u_long cmd, struct devreq *req)
+{
+	static int devctl2_fd = -1;
+
+	if (devctl2_fd == -1) {
+		devctl2_fd = open("/dev/devctl2", O_RDONLY);
+		if (devctl2_fd == -1)
+			return (-1);
+	}
+	return (ioctl(devctl2_fd, cmd, req));
+}
+
+static int
+devctl_simple_request(u_long cmd, const char *name, int flags)
+{
+	struct devreq req;
+
+	memset(&req, 0, sizeof(req));
+	if (strlcpy(req.dr_name, name, sizeof(req.dr_name)) >=
+	    sizeof(req.dr_name)) {
+		errno = EINVAL;
+		return (-1);
+	}
+	req.dr_flags = flags;
+	return (devctl_request(cmd, &req));
+}
+
+int
+devctl_attach(const char *device)
+{
+
+	return (devctl_simple_request(DEV_ATTACH, device, 0));
+}
+
+int
+devctl_detach(const char *device, bool force)
+{
+
+	return (devctl_simple_request(DEV_DETACH, device, force ?
+	    DEVF_FORCE_DETACH : 0));
+}
+
+int
+devctl_enable(const char *device)
+{
+
+	return (devctl_simple_request(DEV_ENABLE, device, 0));
+}
+
+int
+devctl_disable(const char *device, bool force_detach)
+{
+
+	return (devctl_simple_request(DEV_DISABLE, device, force_detach ?
+	    DEVF_FORCE_DETACH : 0));
+}
+
+int
+devctl_set_driver(const char *device, const char *driver, bool force)
+{
+	struct devreq req;
+
+	memset(&req, 0, sizeof(req));
+	if (strlcpy(req.dr_name, device, sizeof(req.dr_name)) >=
+	    sizeof(req.dr_name)) {
+		errno = EINVAL;
+		return (-1);
+	}
+	req.dr_data = __DECONST(char *, driver);
+	if (force)
+		req.dr_flags |= DEVF_SET_DRIVER_DETACH;
+	return (devctl_request(DEV_SET_DRIVER, &req));
+}
diff --git a/lib/libdevctl/devctl.h b/lib/libdevctl/devctl.h
new file mode 100644
index 0000000..3426cce
--- /dev/null
+++ b/lib/libdevctl/devctl.h
@@ -0,0 +1,40 @@
+/*-
+ * Copyright (c) 2014 John Baldwin <jhb@FreeBSD.org>
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef __DEVCTL_H__
+#define	__DEVCTL_H__
+
+#include <stdbool.h>
+
+int	devctl_attach(const char *device);
+int	devctl_detach(const char *device, bool force);
+int	devctl_enable(const char *device);
+int	devctl_disable(const char *device, bool force_detach);
+int	devctl_set_driver(const char *device, const char *driver, bool force);
+
+#endif /* !__DEVCTL_H__ */
diff --git a/share/mk/bsd.libnames.mk b/share/mk/bsd.libnames.mk
index 096b08c..3f30264 100644
--- a/share/mk/bsd.libnames.mk
+++ b/share/mk/bsd.libnames.mk
@@ -38,6 +38,7 @@ LIBCRYPT?=	${DESTDIR}${LIBDIR}/libcrypt.a
 LIBCRYPTO?=	${DESTDIR}${LIBDIR}/libcrypto.a
 LIBCTF?=	${DESTDIR}${LIBDIR}/libctf.a
 LIBCURSES?=	${DESTDIR}${LIBDIR}/libcurses.a
+LIBDEVCTL?=	${DESTDIR}${LIBDIR}/libdevctl.a
 LIBDEVINFO?=	${DESTDIR}${LIBDIR}/libdevinfo.a
 LIBDEVSTAT?=	${DESTDIR}${LIBDIR}/libdevstat.a
 LIBDIALOG?=	${DESTDIR}${LIBDIR}/libdialog.a
diff --git a/sys/conf/files b/sys/conf/files
index 143e863..9d8a183 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -3238,7 +3238,7 @@ libkern/jenkins_hash.c		standard
 libkern/murmur3_32.c		standard
 libkern/mcount.c		optional profiling-routine
 libkern/memcchr.c		standard
-libkern/memchr.c		optional fdt
+libkern/memchr.c		standard
 libkern/memcmp.c		standard
 libkern/qsort.c			standard
 libkern/qsort_r.c		standard
diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
index 55b0dd2..08a967f 100644
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -100,6 +100,7 @@ int		acpi_quirks;
 /* Supported sleep states. */
 static BOOLEAN	acpi_sleep_states[ACPI_S_STATE_COUNT];
 
+static void	acpi_lookup(void *arg, const char *name, device_t *dev);
 static int	acpi_modevent(struct module *mod, int event, void *junk);
 static int	acpi_probe(device_t dev);
 static int	acpi_attach(device_t dev);
@@ -670,8 +671,10 @@ acpi_attach(device_t dev)
     /* Register ACPI again to pass the correct argument of pm_func. */
     power_pm_register(POWER_PM_TYPE_ACPI, acpi_pm_func, sc);
 
-    if (!acpi_disabled("bus"))
+    if (!acpi_disabled("bus")) {
+	EVENTHANDLER_REGISTER(dev_lookup, acpi_lookup, NULL, 1000);
 	acpi_probe_children(dev);
+    }
 
     /* Update all GPEs and enable runtime GPEs. */
     status = AcpiUpdateAllGpes();
@@ -3404,6 +3407,31 @@ acpi_disabled(char *subsys)
     return (0);
 }
 
+static void
+acpi_lookup(void *arg, const char *name, device_t *dev)
+{
+    ACPI_HANDLE handle;
+
+    if (*dev != NULL)
+	return;
+
+    /*
+     * Allow any handle name that is specified as an absolute path and
+     * starts with '\'.  We could restrict this to \_SB and friends,
+     * but see acpi_probe_children() for notes on why we scan the entire
+     * namespace for devices.
+     *
+     * XXX: The pathname argument to AcpiGetHandle() should be fixed to
+     * be const.
+     */
+    if (name[0] != '\\')
+	return;
+    if (ACPI_FAILURE(AcpiGetHandle(ACPI_ROOT_OBJECT, __DECONST(char *, name),
+	&handle)))
+	return;
+    *dev = acpi_get_device(handle);
+}
+
 /*
  * Control interface.
  *
diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c
index cef2db4..bf41b8e 100644
--- a/sys/dev/pci/pci.c
+++ b/sys/dev/pci/pci.c
@@ -35,6 +35,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/malloc.h>
 #include <sys/module.h>
+#include <sys/limits.h>
 #include <sys/linker.h>
 #include <sys/fcntl.h>
 #include <sys/conf.h>
@@ -4924,8 +4925,8 @@ pci_child_location_str_method(device_t dev, device_t child, char *buf,
     size_t buflen)
 {
 
-	snprintf(buf, buflen, "slot=%d function=%d", pci_get_slot(child),
-	    pci_get_function(child));
+	snprintf(buf, buflen, "pci%d:%d:%d:%d", pci_get_domain(child),
+	    pci_get_bus(child), pci_get_slot(child), pci_get_function(child));
 	return (0);
 }
 
@@ -4955,10 +4956,60 @@ pci_assign_interrupt_method(device_t dev, device_t child)
 	    cfg->intpin));
 }
 
+static void
+pci_lookup(void *arg, const char *name, device_t *dev)
+{
+	long val;
+	char *end;
+	int domain, bus, slot, func;
+
+	if (*dev != NULL)
+		return;
+
+	/*
+	 * Accept pciconf-style selectors of either pciD:B:S:F or
+	 * pciB:S:F.  In the latter case, the domain is assumed to
+	 * be zero.
+	 */
+	if (strncmp(name, "pci", 3) != 0)
+		return;
+	val = strtol(name + 3, &end, 10);
+	if (val < 0 || val > INT_MAX || *end != ':')
+		return;
+	domain = val;
+	val = strtol(end + 1, &end, 10);
+	if (val < 0 || val > INT_MAX || *end != ':')
+		return;
+	bus = val;
+	val = strtol(end + 1, &end, 10);
+	if (val < 0 || val > INT_MAX)
+		return;
+	slot = val;
+	if (*end == ':') {
+		val = strtol(end + 1, &end, 10);
+		if (val < 0 || val > INT_MAX || *end != '\0')
+			return;
+		func = val;
+	} else if (*end == '\0') {
+		func = slot;
+		slot = bus;
+		bus = domain;
+		domain = 0;
+	} else
+		return;
+
+	if (domain > PCI_DOMAINMAX || bus > PCI_BUSMAX || slot > PCI_SLOTMAX ||
+	    func > PCIE_ARI_FUNCMAX || (slot != 0 && func > PCI_FUNCMAX))
+		return;
+
+	*dev = pci_find_dbsf(domain, bus, slot, func);
+}
+
 static int
 pci_modevent(module_t mod, int what, void *arg)
 {
 	static struct cdev *pci_cdev;
+	static eventhandler_tag tag;
 
 	switch (what) {
 	case MOD_LOAD:
@@ -4967,9 +5018,13 @@ pci_modevent(module_t mod, int what, void *arg)
 		pci_cdev = make_dev(&pcicdev, 0, UID_ROOT, GID_WHEEL, 0644,
 		    "pci");
 		pci_load_vendor_data();
+		tag = EVENTHANDLER_REGISTER(dev_lookup, pci_lookup, NULL,
+		    1000);
 		break;
 
 	case MOD_UNLOAD:
+		if (tag != NULL)
+			EVENTHANDLER_DEREGISTER(dev_lookup, tag);
 		destroy_dev(pci_cdev);
 		break;
 	}
diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index bb6806c..faf4aa0 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -41,6 +41,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/module.h>
 #include <sys/mutex.h>
 #include <sys/poll.h>
+#include <sys/priv.h>
 #include <sys/proc.h>
 #include <sys/condvar.h>
 #include <sys/queue.h>
@@ -147,6 +148,8 @@ struct device {
 static MALLOC_DEFINE(M_BUS, "bus", "Bus data structures");
 static MALLOC_DEFINE(M_BUS_SC, "bus-sc", "Bus data structures, softc");
 
+static void devctl2_init(void);
+
 #ifdef BUS_DEBUG
 
 static int bus_debug = 1;
@@ -434,6 +437,7 @@ devinit(void)
 	cv_init(&devsoftc.cv, "dev cv");
 	TAILQ_INIT(&devsoftc.devq);
 	knlist_init_mtx(&devsoftc.sel.si_note, &devsoftc.mtx);
+	devctl2_init();
 }
 
 static int
@@ -4998,3 +5002,229 @@ bus_free_resource(device_t dev, int type, struct resource *r)
 		return (0);
 	return (bus_release_resource(dev, type, rman_get_rid(r), r));
 }
+
+/*
+ * /dev/devctl2 implementation.  The existing /dev/devctl device has
+ * implicit semantics on open, so it could not be reused for this.
+ * Another option would be to call this /dev/bus?
+ */
+static int
+find_device(struct devreq *req, device_t *devp)
+{
+	device_t dev;
+
+	/*
+	 * First, ensure that the name is nul terminated.
+	 */
+	if (memchr(req->dr_name, '\0', sizeof(req->dr_name)) == NULL)
+		return (EINVAL);
+
+	/*
+	 * Second, try to find an attached device whose name matches
+	 * 'name'.
+	 */
+	TAILQ_FOREACH(dev, &bus_data_devices, devlink) {
+		if (dev->nameunit != NULL &&
+		    strcmp(dev->nameunit, req->dr_name) == 0) {
+			*devp = dev;
+			return (0);
+		}
+	}
+
+	/* Finally, give device enumerators a chance. */
+	dev = NULL;
+	EVENTHANDLER_INVOKE(dev_lookup, req->dr_name, &dev);
+	if (dev == NULL)
+		return (ENOENT);
+	*devp = dev;
+	return (0);
+}
+
+static bool
+driver_exists(struct device *bus, const char *driver)
+{
+	devclass_t dc;
+
+	for (dc = bus->devclass; dc != NULL; dc = dc->parent) {
+		if (devclass_find_driver_internal(dc, driver) != NULL)
+			return (true);
+	}
+	return (false);
+}
+
+static int
+devctl2_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag,
+    struct thread *td)
+{
+	struct devreq *req;
+	device_t dev;
+	int error, old;
+
+	/* Locate the device to control. */
+	mtx_lock(&Giant);
+	req = (struct devreq *)data;
+	switch (cmd) {
+	case DEV_ATTACH:
+	case DEV_DETACH:
+	case DEV_ENABLE:
+	case DEV_DISABLE:
+	case DEV_SET_DRIVER:
+		error = priv_check(td, PRIV_DRIVER);
+		if (error == 0)
+			error = find_device(req, &dev);
+		break;
+	default:
+		error = ENOTTY;
+		break;
+	}
+	if (error) {
+		mtx_unlock(&Giant);
+		return (error);
+	}
+
+	/* Perform the requested operation. */
+	switch (cmd) {
+	case DEV_ATTACH:
+		if (device_is_attached(dev) && (dev->flags & DF_REBID) == 0)
+			error = EBUSY;
+		else if (!device_is_enabled(dev))
+			error = ENXIO;
+		else
+			error = device_probe_and_attach(dev);
+		break;
+	case DEV_DETACH:
+		if (!device_is_attached(dev)) {
+			error = ENXIO;
+			break;
+		}
+		if (!(req->dr_flags & DEVF_FORCE_DETACH)) {
+			error = device_quiesce(dev);
+			if (error)
+				break;
+		}
+		error = device_detach(dev);
+		break;
+	case DEV_ENABLE:
+		if (device_is_enabled(dev)) {
+			error = EBUSY;
+			break;
+		}
+
+		/*
+		 * If the device has been probed but not attached (e.g.
+		 * when it has been disabled by a loader hint), just
+		 * attach the device rather than doing a full probe.
+		 */
+		device_enable(dev);
+		if (device_is_alive(dev)) {
+			/*
+			 * If the device was disabled via a hint, clear
+			 * the hint.
+			 */
+			if (resource_disabled(dev->driver->name, dev->unit))
+				resource_unset_value(dev->driver->name,
+				    dev->unit, "disabled");
+			error = device_attach(dev);
+		} else
+			error = device_probe_and_attach(dev);
+		break;
+	case DEV_DISABLE:
+		if (!device_is_enabled(dev)) {
+			error = ENXIO;
+			break;
+		}
+
+		if (!(req->dr_flags & DEVF_FORCE_DETACH)) {
+			error = device_quiesce(dev);
+			if (error)
+				break;
+		}
+
+		/*
+		 * Force DF_FIXEDCLASS on around detach to preserve
+		 * the existing name.
+		 */
+		old = dev->flags;
+		dev->flags |= DF_FIXEDCLASS;
+		error = device_detach(dev);
+		if (!(old & DF_FIXEDCLASS))
+			dev->flags &= ~DF_FIXEDCLASS;
+		if (error == 0)
+			device_disable(dev);
+		break;
+	case DEV_SET_DRIVER: {
+		devclass_t dc;
+		char driver[128];
+
+		error = copyinstr(req->dr_data, driver, sizeof(driver), NULL);
+		if (error)
+			break;
+		if (driver[0] == '\0') {
+			error = EINVAL;
+			break;
+		}
+		if (dev->devclass != NULL &&
+		    strcmp(driver, dev->devclass->name) == 0)
+			/* XXX: Could possibly force DF_FIXEDCLASS on? */
+			break;
+
+		/*
+		 * Scan drivers for this device's bus looking for at
+		 * least one matching driver.
+		 */
+		if (dev->parent == NULL) {
+			error = EINVAL;
+			break;
+		}
+		if (!driver_exists(dev->parent, driver)) {
+			error = ENOENT;
+			break;
+		}
+		dc = devclass_create(driver);
+		if (dc == NULL) {
+			error = ENOMEM;
+			break;
+		}
+
+		/* Detach device if necessary. */
+		if (device_is_attached(dev)) {
+			if (req->dr_flags & DEVF_SET_DRIVER_DETACH)
+				error = device_detach(dev);
+			else
+				error = EBUSY;
+			if (error)
+				break;
+		}
+
+		/* Clear any previously-fixed device class and unit. */
+		if (dev->flags & DF_FIXEDCLASS)
+			devclass_delete_device(dev->devclass, dev);
+		dev->flags |= DF_WILDCARD;
+		dev->unit = -1;
+
+		/* Force the new device class. */
+		error = devclass_add_device(dc, dev);
+		if (error)
+			break;
+		dev->flags |= DF_FIXEDCLASS;
+		error = device_probe_and_attach(dev);
+		break;
+	}
+	}
+	mtx_unlock(&Giant);
+	return (error);
+}
+
+static struct cdevsw devctl2_cdevsw = {
+	.d_version =	D_VERSION,
+	.d_ioctl =	devctl2_ioctl,
+	.d_name =	"devctl2",
+};
+
+static void
+devctl2_init(void)
+{
+
+	make_dev_credf(MAKEDEV_ETERNAL, &devctl2_cdevsw, 0, NULL,
+	    UID_ROOT, GID_WHEEL, 0600, "devctl2");
+}
diff --git a/sys/kern/subr_hints.c b/sys/kern/subr_hints.c
index f9085b2..08f8e8c 100644
--- a/sys/kern/subr_hints.c
+++ b/sys/kern/subr_hints.c
@@ -461,3 +461,31 @@ resource_disabled(const char *name, int unit)
 	       return (0);
 	return (value);
 }
+
+/*
+ * Clear a value associated with a device by removing it from
+ * the kernel environment.  This only removes a hint for an
+ * exact unit.
+ */
+int
+resource_unset_value(const char *name, int unit, const char *resname)
+{
+	char varname[128];
+	const char *retname, *retvalue;
+	int error, line;
+	size_t len;
+
+	line = 0;
+	error = resource_find(&line, NULL, name, &unit, resname, NULL,
+	    &retname, NULL, NULL, NULL, NULL, &retvalue);
+	if (error)
+		return (error);
+
+	retname -= strlen("hint.");
+	len = retvalue - retname - 1;
+	if (len > sizeof(varname) - 1)
+		return (ENAMETOOLONG);
+	memcpy(varname, retname, len);
+	varname[len] = '\0';
+	return (unsetenv(varname));
+}
diff --git a/sys/sys/bus.h b/sys/sys/bus.h
index fd858ca..4ab8249 100644
--- a/sys/sys/bus.h
+++ b/sys/sys/bus.h
@@ -31,6 +31,7 @@
 
 #include <machine/_limits.h>
 #include <sys/_bus_dma.h>
+#include <sys/ioccom.h>
 
 /**
  * @defgroup NEWBUS newbus - a generic framework for managing devices
@@ -75,9 +76,43 @@ struct u_device {
 	/* XXX more driver info? */
 };
 
+/**
+ * @brief Device request structure used for ioctl's.
+ *
+ * Used for ioctl's on /dev/devctl2.  All device ioctl's
+ * must have parameter definitions which begin with dr_name.
+ */
+struct devreq_buffer {
+	void	*buffer;
+	size_t	length;
+};
+
+struct devreq {
+	char		dr_name[128];
+	int		dr_flags;		/* request-specific flags */
+	union {
+		struct devreq_buffer dru_buffer;
+		void	*dru_data;
+	} dr_dru;
+#define	dr_buffer	dr_dru.dru_buffer	/* variable-sized buffer */
+#define	dr_data		dr_dru.dru_data		/* fixed-size buffer */
+};
+
+#define	DEV_ATTACH	_IOW('D', 1, struct devreq)
+#define	DEV_DETACH	_IOW('D', 2, struct devreq)
+#define	DEV_ENABLE	_IOW('D', 3, struct devreq)
+#define	DEV_DISABLE	_IOW('D', 4, struct devreq)
+#define	DEV_SET_DRIVER	_IOW('D', 7, struct devreq)
+
+/* Flags for DEV_DETACH and DEV_DISABLE. */
+#define	DEVF_FORCE_DETACH	0x0000001
+
+/* Flags for DEV_SET_DRIVER. */
+#define	DEVF_SET_DRIVER_DETACH	0x0000001	/* Detach existing driver. */
+
 #ifdef _KERNEL
 
-#include <sys/queue.h>
+#include <sys/eventhandler.h>
 #include <sys/kobj.h>
 
 /**
@@ -94,6 +129,14 @@ void devctl_queue_data_f(char *__data, int __flags);
 void devctl_queue_data(char *__data);
 
 /**
+ * Device name parsers.  Hook to allow device enumerators to map
+ * scheme-specific names to a device.
+ */
+typedef void (*dev_lookup_fn)(void *arg, const char *name,
+    device_t *result);
+EVENTHANDLER_DECLARE(dev_lookup, dev_lookup_fn);
+
+/**
  * @brief A device driver (included mainly for compatibility with
  * FreeBSD 4.x).
  */
@@ -454,6 +497,7 @@ struct sysctl_oid *device_get_sysctl_tree(device_t dev);
 int	device_is_alive(device_t dev);	/* did probe succeed? */
 int	device_is_attached(device_t dev);	/* did attach succeed? */
 int	device_is_enabled(device_t dev);
+int	device_is_suspended(device_t dev);
 int	device_is_quiet(device_t dev);
 int	device_print_prettyname(device_t dev);
 int	device_printf(device_t dev, const char *, ...) __printflike(2, 3);
@@ -517,6 +561,8 @@ int	resource_set_long(const char *name, int unit, const char *resname,
 			  long value);
 int	resource_set_string(const char *name, int unit, const char *resname,
 			    const char *value);
+int	resource_unset_value(const char *name, int unit, const char *resname);
+
 /*
  * Functions for maintaining and checking consistency of
  * bus information exported to userspace.
diff --git a/usr.sbin/Makefile b/usr.sbin/Makefile
index 7d58988..c6d4b6e 100644
--- a/usr.sbin/Makefile
+++ b/usr.sbin/Makefile
@@ -20,6 +20,7 @@ SUBDIR=	adduser \
 	ctld \
 	daemon \
 	dconschat \
+	devctl \
 	devinfo \
 	digictl \
 	diskinfo \
diff --git a/usr.sbin/devctl/Makefile b/usr.sbin/devctl/Makefile
new file mode 100644
index 0000000..6193100
--- /dev/null
+++ b/usr.sbin/devctl/Makefile
@@ -0,0 +1,9 @@
+# $FreeBSD$
+
+PROG=	devctl
+MAN=	devctl.8
+
+DPADD=	${LIBDEVCTL}
+LDADD=	-ldevctl
+
+.include <bsd.prog.mk>
diff --git a/usr.sbin/devctl/devctl.8 b/usr.sbin/devctl/devctl.8
new file mode 100644
index 0000000..add170d
--- /dev/null
+++ b/usr.sbin/devctl/devctl.8
@@ -0,0 +1,126 @@
+.\"
+.\" Copyright (c) 2015 John Baldwin <jhb@FreeBSD.org>
+.\" 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.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd February 5, 2015
+.Dt DEVCTL 8
+.Os
+.Sh NAME
+.Nm devctl
+.Nd device control utility
+.Sh SYNOPSIS
+.Nm
+.Cm attach
+.Ar device
+.Nm
+.Cm detach
+.Op Fl f
+.Ar device
+.Nm
+.Cm disable
+.Op Fl f
+.Ar device
+.Nm
+.Cm enable
+.Ar device
+.Nm
+.Cm set driver
+.Op Fl f
+.Ar device driver
+.Sh DESCRIPTION
+The
+.Nm
+utility adjusts the state of individual devices in the kernel's
+internal device hierarchy.
+Each invocation of
+.Nm
+consists of a single command followed by command-specific arguments.
+Each command operates on a single device specified via the
+.Ar device
+argument.
+The
+.Ar device
+may be specified either as the name of an existing device or as a
+bus-specific address.
+More details on supported address formats can be found in
+.Xr devctl 3 .
+.Pp
+The following commands are supported:
+.Bl -tag -width indent
+.It Cm attach Ar device
+Force the kernel to re-probe the device.
+If a suitable driver is found,
+it is attached to the device.
+.It Xo Cm detach
+.Op Fl f
+.Ar device
+.Xc
+Detach the device from its current device driver.
+If the
+.Fl f
+flag is specified,
+the device driver will be detached even if the device is busy.
+.It Xo Cm disable
+.Op Fl f
+.Ar device
+.Xc
+Disable a device.
+If the device is currently attached to a device driver,
+the device driver will be detached from the device,
+but the device will retain its current name.
+If the
+.Fl f
+flag is specified,
+the device driver will be detached even if the device is busy.
+.It Cm enable Ar device
+Enable a device.
+The device will probe and attach if a suitable device driver is found.
+Note that this can re-enable a device disabled at boot time via a
+loader tunable.
+.It Xo Cm set driver
+.Op Fl f
+.Ar device driver
+.Xc
+Force the device to use a device driver named
+.Ar driver .
+If the device is already attached to a device driver and the
+.Fl f
+flag is specified,
+the device will be detached from its current device driver before it is
+attached to the new device driver.
+If the device is already attached to a device driver and the
+.Fl f
+flag is not specified,
+the device will not be changed.
+.El
+.Sh SEE ALSO
+.Xr devctl 3 ,
+.Xr devinfo 8
+.Sh HISTORY
+The
+.Nm
+utility first appeared in
+.Fx 11.0 .
diff --git a/usr.sbin/devctl/devctl.c b/usr.sbin/devctl/devctl.c
new file mode 100644
index 0000000..fdabd4f
--- /dev/null
+++ b/usr.sbin/devctl/devctl.c
@@ -0,0 +1,256 @@
+/*-
+ * Copyright (c) 2014 John Baldwin <jhb@FreeBSD.org>
+ * 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/linker_set.h>
+#include <devctl.h>
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <unistd.h>
+
+struct devctl_command {
+	const char *name;
+	int (*handler)(int ac, char **av);
+};
+
+#define	DEVCTL_DATASET(name)	devctl_ ## name ## _table
+
+#define	DEVCTL_COMMAND(set, name, function)				\
+	static struct devctl_command function ## _devctl_command =	\
+	{ #name, function };						\
+	DATA_SET(DEVCTL_DATASET(set), function ## _devctl_command)
+
+#define	DEVCTL_TABLE(set, name)						\
+	SET_DECLARE(DEVCTL_DATASET(name), struct devctl_command);	\
+									\
+	static int							\
+	devctl_ ## name ## _table_handler(int ac, char **av)		\
+	{								\
+		return (devctl_table_handler(SET_BEGIN(DEVCTL_DATASET(name)), \
+		    SET_LIMIT(DEVCTL_DATASET(name)), ac, av));		\
+	}								\
+	DEVCTL_COMMAND(set, name, devctl_ ## name ## _table_handler)
+
+static int	devctl_table_handler(struct devctl_command **start,
+    struct devctl_command **end, int ac, char **av);
+
+SET_DECLARE(DEVCTL_DATASET(top), struct devctl_command);
+
+DEVCTL_TABLE(top, set);
+
+static void
+usage(void)
+{
+	fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n",
+	    "usage: devctl attach device",
+	    "       devctl detach [-f] device",
+	    "       devctl disable [-f] device",
+	    "       devctl enable device",
+	    "       devctl set driver [-f] device driver");
+	exit(1);
+}
+
+static int
+devctl_table_handler(struct devctl_command **start,
+    struct devctl_command **end, int ac, char **av)
+{
+	struct devctl_command **cmd;
+
+	if (ac < 2) {
+		warnx("The %s command requires a sub-command.", av[0]);
+		return (EINVAL);
+	}
+	for (cmd = start; cmd < end; cmd++) {
+		if (strcmp((*cmd)->name, av[1]) == 0)
+			return ((*cmd)->handler(ac - 1, av + 1));
+	}
+
+	warnx("%s is not a valid sub-command of %s.", av[1], av[0]);
+	return (ENOENT);
+}
+
+static int
+help(int ac __unused, char **av __unused)
+{
+
+	usage();
+	return (0);
+}
+DEVCTL_COMMAND(top, help, help);
+
+static int
+attach(int ac, char **av)
+{
+
+	if (ac != 2)
+		usage();
+	if (devctl_attach(av[1]) < 0)
+		err(1, "Failed to attach %s", av[1]);
+	return (0);
+}
+DEVCTL_COMMAND(top, attach, attach);
+
+static void
+detach_usage(void)
+{
+
+	fprintf(stderr, "usage: devctl detach [-f] device\n");
+	exit(1);
+}
+
+static int
+detach(int ac, char **av)
+{
+	bool force;
+	int ch;
+
+	force = false;
+	while ((ch = getopt(ac, av, "f")) != -1)
+		switch (ch) {
+		case 'f':
+			force = true;
+			break;
+		default:
+			detach_usage();
+		}
+	ac -= optind;
+	av += optind;
+
+	if (ac != 1)
+		detach_usage();
+	if (devctl_detach(av[0], force) < 0)
+		err(1, "Failed to detach %s", av[0]);
+	return (0);
+}
+DEVCTL_COMMAND(top, detach, detach);
+
+static void
+disable_usage(void)
+{
+
+	fprintf(stderr, "usage: devctl disable [-f] device\n");
+	exit(1);
+}
+
+static int
+disable(int ac, char **av)
+{
+	bool force;
+	int ch;
+
+	force = false;
+	while ((ch = getopt(ac, av, "f")) != -1)
+		switch (ch) {
+		case 'f':
+			force = true;
+			break;
+		default:
+			disable_usage();
+		}
+	ac -= optind;
+	av += optind;
+
+	if (ac != 1)
+		disable_usage();
+	if (devctl_disable(av[0], force) < 0)
+		err(1, "Failed to disable %s", av[0]);
+	return (0);
+}
+DEVCTL_COMMAND(top, disable, disable);
+
+static int
+enable(int ac, char **av)
+{
+
+	if (ac != 2)
+		usage();
+	if (devctl_enable(av[1]) < 0)
+		err(1, "Failed to enable %s", av[1]);
+	return (0);
+}
+DEVCTL_COMMAND(top, enable, enable);
+
+static void
+set_driver_usage(void)
+{
+
+	fprintf(stderr, "usage: devctl set driver [-f] device driver\n");
+	exit(1);
+}
+
+static int
+set_driver(int ac, char **av)
+{
+	bool force;
+	int ch;
+
+	force = false;
+	while ((ch = getopt(ac, av, "f")) != -1)
+		switch (ch) {
+		case 'f':
+			force = true;
+			break;
+		default:
+			set_driver_usage();
+		}
+	ac -= optind;
+	av += optind;
+
+	if (ac != 2)
+		set_driver_usage();
+	if (devctl_set_driver(av[0], av[1], force) < 0)
+		err(1, "Failed to set %s driver to %s", av[0], av[1]);
+	return (0);
+}
+DEVCTL_COMMAND(set, driver, set_driver);
+
+int
+main(int ac, char *av[])
+{
+	struct devctl_command **cmd;
+
+	if (ac == 1)
+		usage();
+	ac--;
+	av++;
+
+	SET_FOREACH(cmd, DEVCTL_DATASET(top)) {
+		if (strcmp((*cmd)->name, av[0]) == 0) {
+			if ((*cmd)->handler(ac, av) != 0)
+				return (1);
+			else
+				return (0);
+		}
+	}
+	warnx("Unknown command %s.", av[0]);
+	return (1);
+}