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 device_is_suspended() function to check DF_SUSPENDED.
- 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.

Reviewed by:	imp (parts)
Requested by:	imp (changing PCI location string)
Relnotes:	yes

17 files changed, 1328 insertions, 4 deletions

diff --git a/contrib/mdocml/lib.in b/contrib/mdocml/lib.in
index a5522ef..a1ce062 100644
--- a/contrib/mdocml/lib.in
+++ b/contrib/mdocml/lib.in
@@ -41,6 +41,7 @@ LINE("libcrypt",	"Crypt Library (libcrypt, \\-lcrypt)")
 LINE("libcurses",	"Curses Library (libcurses, \\-lcurses)")
 LINE("libcuse", 	"Userland Character Device Library (libcuse, \\-lcuse)")
 LINE("libdevattr",	"Device attribute and event library (libdevattr, \\-ldevattr)")
+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 c00af75..fdab453 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -41,6 +41,7 @@ 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..be869f9
--- /dev/null
+++ b/lib/libdevctl/devctl.3
@@ -0,0 +1,295 @@
+.\"
+.\" 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 ,
+.Nm devctl_resume ,
+.Nm devctl_suspend
+.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_resume "const char *device"
+.Ft int
+.Fn devctl_suspend "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_suspend
+function suspends a device.
+This may include placing the device in a reduced power state,
+but any device driver currently attached to the device will remain attached.
+.Pp
+The
+.Fn devctl_resume
+function resumes a suspended device to a fully working state.
+.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_suspend devctl_resume 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_suspend
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er EBUSY
+The device is already suspended.
+.It Bq Er EINVAL
+The device to be suspended is the root bus device.
+.El
+.Pp
+The
+.Fn devctl_resume
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The device is not suspended.
+.It Bq Er EINVAL
+The device to be resumed is the root bus device.
+.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 .
+.Sh BUGS
+If a device is suspended individually via
+.Fn devctl_suspend
+and the entire machine is subsequently suspended,
+the device will be resumed when the machine resumes.
diff --git a/lib/libdevctl/devctl.c b/lib/libdevctl/devctl.c
new file mode 100644
index 0000000..7be431e
--- /dev/null
+++ b/lib/libdevctl/devctl.c
@@ -0,0 +1,124 @@
+/*-
+ * 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_suspend(const char *device)
+{
+
+	return (devctl_simple_request(DEV_SUSPEND, device, 0));
+}
+
+int
+devctl_resume(const char *device)
+{
+
+	return (devctl_simple_request(DEV_RESUME, device, 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..f773b11
--- /dev/null
+++ b/lib/libdevctl/devctl.h
@@ -0,0 +1,42 @@
+/*-
+ * 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_suspend(const char *device);
+int	devctl_resume(const char *device);
+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 00f0a0a..d84747e 100644
--- a/share/mk/bsd.libnames.mk
+++ b/share/mk/bsd.libnames.mk
@@ -39,6 +39,7 @@ 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/share/mk/src.libnames.mk b/share/mk/src.libnames.mk
index b8570ed..a688089 100644
--- a/share/mk/src.libnames.mk
+++ b/share/mk/src.libnames.mk
@@ -72,6 +72,7 @@ _LIBRARIES=	\
 		ctf \
 		cuse \
 		cxxrt \
+		devctl \
 		devinfo \
 		devstat \
 		dialog \
diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
index a4732c4..bf2cc54 100644
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -101,6 +101,7 @@ 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);
@@ -671,8 +672,10 @@ 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();
@@ -3401,6 +3404,31 @@ 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 8f87851..263904b 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>
@@ -4824,8 +4825,8 @@ 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);
 }
 
@@ -4855,10 +4856,60 @@ 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:
@@ -4867,9 +4918,13 @@ 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 269be94..1c7b21c 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>
@@ -139,6 +140,8 @@ 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;
@@ -423,6 +426,7 @@ 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
@@ -2639,6 +2643,15 @@ device_is_attached(device_t dev)
 }
 
 /**
+ * @brief Return non-zero if the device is currently suspended.
+ */
+int
+device_is_suspended(device_t dev)
+{
+	return ((dev->flags & DF_SUSPENDED) != 0);
+}
+
+/**
  * @brief Set the devclass of a device
  * @see devclass_add_device().
  */
@@ -5022,3 +5035,253 @@ 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_SUSPEND:
+	case DEV_RESUME:
+	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_SUSPEND:
+		if (device_is_suspended(dev)) {
+			error = EBUSY;
+			break;
+		}
+		if (device_get_parent(dev) == NULL) {
+			error = EINVAL;
+			break;
+		}
+		error = BUS_SUSPEND_CHILD(device_get_parent(dev), dev);
+		break;
+	case DEV_RESUME:
+		if (!device_is_suspended(dev)) {
+			error = EINVAL;
+			break;
+		}
+		if (device_get_parent(dev) == NULL) {
+			error = EINVAL;
+			break;
+		}
+		error = BUS_RESUME_CHILD(device_get_parent(dev), 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 25838ee..00cfbf1 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 (kern_unsetenv(varname));
+}
diff --git a/sys/sys/bus.h b/sys/sys/bus.h
index f15dd34..d6dc535 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
@@ -86,9 +87,45 @@ struct u_device {
 #define	DF_REBID	0x80		/* Can rebid after attach */
 #define	DF_SUSPENDED	0x100		/* Device is suspended. */
 
+/**
+ * @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_SUSPEND	_IOW('D', 5, struct devreq)
+#define	DEV_RESUME	_IOW('D', 6, 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>
 
 /**
@@ -105,6 +142,14 @@ 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).
  */
@@ -465,6 +510,7 @@ 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);
@@ -528,6 +574,8 @@ 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 918678b..30d843d 100644
--- a/usr.sbin/Makefile
+++ b/usr.sbin/Makefile
@@ -19,6 +19,7 @@ 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..5a6e19d
--- /dev/null
+++ b/usr.sbin/devctl/Makefile
@@ -0,0 +1,9 @@
+# $FreeBSD$
+
+PROG=	devctl
+MAN=	devctl.8
+MAN=
+
+LIBADD=	devctl
+
+.include <bsd.prog.mk>
diff --git a/usr.sbin/devctl/devctl.8 b/usr.sbin/devctl/devctl.8
new file mode 100644
index 0000000..77c803a
--- /dev/null
+++ b/usr.sbin/devctl/devctl.8
@@ -0,0 +1,137 @@
+.\"
+.\" 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 suspend
+.Ar device
+.Nm
+.Cm resume
+.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 Cm suspend Ar device
+Suspend a device.
+This may include placing the device in a reduced power state.
+.It Cm resume device
+Resume a suspended device to a fully working state.
+.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..076c650
--- /dev/null
+++ b/usr.sbin/devctl/devctl.c
@@ -0,0 +1,282 @@
+/*-
+ * 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%s\n%s\n",
+	    "usage: devctl attach device",
+	    "       devctl detach [-f] device",
+	    "       devctl disable [-f] device",
+	    "       devctl enable device",
+	    "       devctl suspend device",
+	    "       devctl resume 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 int
+suspend(int ac, char **av)
+{
+
+	if (ac != 2)
+		usage();
+	if (devctl_suspend(av[1]) < 0)
+		err(1, "Failed to suspend %s", av[1]);
+	return (0);
+}
+DEVCTL_COMMAND(top, suspend, suspend);
+
+static int
+resume(int ac, char **av)
+{
+
+	if (ac != 2)
+		usage();
+	if (devctl_resume(av[1]) < 0)
+		err(1, "Failed to resume %s", av[1]);
+	return (0);
+}
+DEVCTL_COMMAND(top, resume, resume);
+
+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);
+}