Implement devctl(8) command 'reset', using DEV_RESET /dev/devctl2 ioctl.

Reviewed by:	imp (previous version), jhb (previous version)
Sponsored by:	Mellanox Technologies
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D19646

lib/libdevctl/devctl.3

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 22, 2018
+.Dd April 4, 2019
 .Dt DEVCTL 3
 .Os
 .Sh NAME
@@ -37,6 +37,7 @@
 .Nm devctl_enable ,
 .Nm devctl_freeze ,
 .Nm devctl_rescan ,
+.Nm devctl_reset ,
 .Nm devctl_resume ,
 .Nm devctl_set_driver ,
 .Nm devctl_suspend ,
@@ -63,6 +64,8 @@
 .Ft int
 .Fn devctl_rescan "const char *device"
 .Ft int
+.Fn devctl_reset "const char *device" "bool detach"
+.Ft int
 .Fn devctl_resume "const char *device"
 .Ft int
 .Fn devctl_set_driver "const char *device" "const char *driver" "bool force"
@@ -204,6 +207,15 @@ The
 .Fn devctl_thaw
 function resumes (thaws the freeze) probe and attach processing
 initiated in response to drivers being loaded.
+.Pp
+The
+.Fn devctl_reset
+function resets the specified device using bus-specific reset method.
+The
+.Fa detach
+argument, if true, specifies that the device driver is detached before
+the reset, and re-attached afterwards.
+If false, the device is suspended before the reset, and resumed after.
 .Sh RETURN VALUES
 .Rv -std devctl_attach devctl_clear_driver devctl_delete devctl_detach \
 devctl_disable devctl_enable devctl_suspend devctl_rescan devctl_resume \
@@ -377,6 +389,21 @@ is false.
 .Fa dev
 is the root device of the device tree.
 .El
+.Pp
+The
+.Fn devctl_reset
+function may fail if:
+.Bl -tag -width Er
+.It Bq Er ENXIO
+The bus does not implement the reset method.
+.It Bq Er ETIMEDOUT
+The device failed to respond after the reset in the time limits
+specific to the bus.
+.El
+The
+.Fn devctl_reset
+function may also return errors caused by the attach, detach, suspend,
+and resume methods of the device driver.
 .Sh SEE ALSO
 .Xr devinfo 3 ,
 .Xr devstat 3 ,
@@ -391,3 +418,20 @@ 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.
+.Pp
+Similarly, if the device is suspended, and
+.Fn devctl_reset
+is called on the device with
+.Fa detach
+set to
+.Va false ,
+the device is resumed by the
+.Fn devctl_reset
+call.
+Or, if the driver for the device is detached manually, and
+.Fn devctl_reset
+is called on the device with
+.Fa detach
+set to
+.Va true ,
+device reset re-attaches the driver.

lib/libdevctl/devctl.c

@@ -158,3 +158,11 @@ devctl_thaw(void)
 
 	return (devctl_simple_request(DEV_THAW, "", 0));
 }
+
+int
+devctl_reset(const char *device, bool detach)
+{
+
+	return (devctl_simple_request(DEV_RESET, device, detach ?
+	    DEVF_RESET_DETACH : 0));
+}

lib/libdevctl/devctl.h

@@ -43,6 +43,7 @@ int	devctl_rescan(const char *device);
 int	devctl_delete(const char *device, bool force);
 int	devctl_freeze(void);
 int	devctl_thaw(void);
+int	devctl_reset(const char *device, bool detach);
 __END_DECLS
 
 #endif /* !__DEVCTL_H__ */

usr.sbin/devctl/devctl.8

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 29, 2016
+.Dd April 4, 2019
 .Dt DEVCTL 8
 .Os
 .Sh NAME
@@ -66,6 +66,10 @@
 .Cm delete
 .Op Fl f
 .Ar device
+.Nm
+.Cm reset
+.Op Fl d
+.Ar device
 .Sh DESCRIPTION
 The
 .Nm
@@ -166,7 +170,35 @@ the device will be deleted even if it is physically present.
 This command should be used with care as a device that is deleted but present
 can no longer be used unless the parent bus device rediscovers the device via
 a rescan request.
+.It Xo Cm reset
+.Op Fl d
+.Ar device
+.Xc
+Reset the device, using bus-specific reset method.
+Drivers for the devices being reset are suspended around the reset.
+If the
+.Fl d
+option is specified, drivers are detached instead.
+.Pp
+Currently, resets are implemented for PCIe buses and PCI devices.
+For PCIe bus, the link is disabled and then re-trained, causing all
+children of the bus to reset.
+Use
+.Fl p
+option of
+.Xr devinfo 8
+tool to report parent bus for the device.
+For PCI device, if Function-Level Reset is implemented by it, FLR is
+tried first; if failed or not implemented, power reset is tried.
+.Pp
+If you have detached or suspended a child device explicitly and then
+do a reset, the child device will end up attached.
 .El
+.Sh BUGS
+Currently there is no administrative flag to prevent re-attach or resume
+of the manually detached or suspended devices after reset.
+Similarly, there is no flag to prevent un-suspending of the the manually
+suspended devices after system resume.
 .Sh SEE ALSO
 .Xr devctl 3 ,
 .Xr devinfo 8

usr.sbin/devctl/devctl.c

@@ -82,7 +82,9 @@ usage(void)
 	    "       devctl rescan device\n"
 	    "       devctl delete [-f] device\n"
 	    "       devctl freeze\n"
-	    "       devctl thaw\n");
+	    "       devctl thaw\n"
+	    "       devctl reset [-d] device\n"
+	    );
 	exit(1);
 }
 
@@ -384,6 +386,40 @@ thaw(int ac, char **av __unused)
 }
 DEVCTL_COMMAND(top, thaw, thaw);
 
+static void
+reset_usage(void)
+{
+
+	fprintf(stderr, "usage: devctl reset [-d] device\n");
+	exit(1);
+}
+
+static int
+reset(int ac, char **av)
+{
+	bool detach;
+	int ch;
+
+	detach = false;
+	while ((ch = getopt(ac, av, "d")) != -1)
+		switch (ch) {
+		case 'd':
+			detach = true;
+			break;
+		default:
+			reset_usage();
+		}
+	ac -= optind;
+	av += optind;
+
+	if (ac != 1)
+		reset_usage();
+	if (devctl_reset(av[0], detach) < 0)
+		err(1, "Failed to reset %s", av[0]);
+	return (0);
+}
+DEVCTL_COMMAND(top, reset, reset);
+
 int
 main(int ac, char *av[])
 {