.\"- .\" Copyright (c) 1992, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" This software was developed by the Computer Systems Engineering group .\" at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and .\" contributed to Berkeley. .\" .\" 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. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. .\" from: OpenBSD: openprom.4,v 1.9 2004/03/22 22:07:21 miod Exp .\" .\"- .\" Copyright (c) 2005 Marius Strobl .\" 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 ``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 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. .\" .Dd January 16, 2021 .Dt OPENFIRM 4 .Os .Sh NAME .Nm openfirm .Nd "Open Firmware interface" .Sh SYNOPSIS .In sys/types.h .In sys/ioctl.h .In dev/ofw/openfirmio.h .Sh DESCRIPTION The .Pa /dev/openfirm device is an interface to the .Tn Open Firmware device tree. This interface is highly stylized. It uses .Xr ioctl 2 calls for all operations. These calls refer to the nodes in the .Tn Open Firmware device tree. The nodes are represented by package handles, which are simply integer values describing data areas. Occasionally a package handle of 0 may be used or returned instead, as described below. .Pp The calls that only take and/or return the package handle of a node use a pointer to a .Vt phandle_t for this purpose. The others use a pointer to a .Vt "struct ofiocdesc" descriptor, which has the following definition: .Bd -literal struct ofiocdesc { phandle_t of_nodeid; int of_namelen; const char *of_name; int of_buflen; char *of_buf; }; .Ed .Pp The .Va of_nodeid member is the package handle of the node that is passed in or returned. Strings are passed in via the .Va of_name member of .Va of_namelen length. The maximum accepted length of .Va of_name is .Dv OFIOCMAXNAME . The .Va of_buf member is used to return strings except for the .Dv OFIOCSET call where it is also used to pass in a string. In the latter case the maximum accepted length of .Va of_buf is .Dv OFIOCMAXVALUE . Generally, .Va of_buf works in a value-result fashion. At entry to the .Xr ioctl 2 call, .Va of_buflen is expected to reflect the buffer size. On return, .Va of_buflen is updated to reflect the buffer contents. .Pp The following .Xr ioctl 2 calls are supported: .Bl -tag -width ".Dv OFIOCGETOPTNODE" .It Dv OFIOCGETOPTNODE Uses a .Vt phandle_t . Takes nothing and returns the package handle of the .Pa /options node. .It Dv OFIOCGETNEXT Uses a .Vt phandle_t . Takes the package handle of a node and returns the package handle of the next node in the .Tn Open Firmware device tree. The node following the last node has a package handle of 0. The node following the node with the package handle of 0 is the first node. .It Dv OFIOCGETCHILD Uses a .Vt phandle_t . Takes the package handle of a node and returns the package handle of the first child of that node. This child may have siblings. These can be determined by using .Dv OFIOCGETNEXT . If the node does not have a child, a package handle of 0 is returned. .It Dv OFIOCGET Uses a .Vt "struct ofiocdesc" . Takes the package handle of a node and the name of a property. Returns the property value and its length. If no such property is associated with that node, the length of the value is set to \-1. If the named property exists but has no value, the length of the value is set to 0. .It Dv OFIOCGETPROPLEN Uses a .Vt "struct ofiocdesc" . Takes the package handle of a node and the name of a property. Returns the length of the property value. This call is the same as .Dv OFIOCGET except that only the length of the property value is returned. It can be used to determine whether a node has a particular property or whether a property has a value without the need to provide memory for storing the value. .It Dv OFIOCSET Uses a .Vt "struct ofiocdesc" . Takes the package handle of a node, the name of a property and a property value. Returns the property value and the length that actually have been written. The .Tn Open Firmware may choose to truncate the value if it is too long or write a valid value instead if the given value is invalid for the particular property. Therefore the returned value should be checked. The .Tn Open Firmware may also completely refuse to write the given value to the property. In this case .Er EINVAL is returned. .It Dv OFIOCNEXTPROP Uses a .Vt "struct ofiocdesc" . Takes the package handle of a node and the name of a property. Returns the name and the length of the next property of the node. If the property referenced by the given name is the last property of the node, .Er ENOENT is returned. .It Dv OFIOCFINDDEVICE Uses a .Vt "struct ofiocdesc" . Takes the name or alias name of a device node. Returns package handle of the node. If no matching node is found, .Er ENOENT is returned. .El .Sh FILES .Bl -tag -width ".Pa /dev/openfirm" .It Pa /dev/openfirm Open Firmware interface node .El .Sh DIAGNOSTICS The following may result in rejection of an operation: .Bl -tag -width Er .It Bq Er EBADF The requested operation requires permissions not specified at the call to .Fn open . .It Bq Er EINVAL The given package handle is not 0 and does not correspond to any valid node, or the given package handle is 0 where 0 is not allowed. .It Bq Er ENAMETOOLONG The given name or value exceeds the maximum allowed length of .Dv OFIOCMAXNAME and .Dv OFIOCMAXVALUE bytes respectively. .El .Sh SEE ALSO .Xr ioctl 2 , .Xr ofwdump 8 .Rs .%Q "IEEE Standards Organization" .%B "IEEE Std 1275-1994:" .%B "IEEE Standard for Boot Firmware (Initialization Configuration) Firmware:" .%B Core Requirements and Practices" .%O ISBN 1-55937-426-8 .Re .Sh HISTORY The .Nm interface first appeared in .Nx 1.6 . The first .Fx version to include it was .Fx 5.0 . .Sh AUTHORS .An -nosplit The .Nm interface was ported to .Fx by .An Thomas Moestl Aq Mt tmm@FreeBSD.org . This manual page was written by .An Marius Strobl Aq Mt marius@FreeBSD.org based on the .Ox manual page for .Xr openprom 4 . .Sh CAVEATS Due to limitations within .Tn Open Firmware itself, these functions run at elevated priority and may adversely affect system performance. .Pp For at least the .Pa /options node the property value passed in to the .Dv OFIOCSET call has to be null-terminated and the value length passed in has to include the terminating .Ql \e0 . However, as with the .Dv OFIOCGET call, the returned value length does not include the terminating .Ql \e0 .