1.\" 2.\" Copyright (c) 2018 Oleksandr Tymoshenko <gonzo@FreeBSD.org> 3.\" 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.Dd April 9, 2018 27.Dt OF_NODE_FROM_XREF 9 28.Os 29.Sh NAME 30.Nm OF_node_from_xref , 31.Nm OF_xref_from_node 32.Nd convert between kernel phandle and effective phandle 33.Sh SYNOPSIS 34.In dev/ofw/ofw_bus.h 35.In dev/ofw/ofw_bus_subr.h 36.Ft phandle_t 37.Fn OF_node_from_xref "phandle_t xref" 38.Ft phandle_t 39.Fn OF_xref_from_node "phandle_t node" 40.Sh DESCRIPTION 41Some OpenFirmware implementations (FDT, IBM) have a concept 42of effective phandle or xrefs. 43They are used to cross-reference device tree nodes. 44For instance, a framebuffer controller may refer to a GPIO 45controller and pin that controls the backlight. 46In this example, the GPIO node would have a cell (32-bit integer) 47property with a reserved name like "phandle" or "linux,phandle" 48whose value uniquely identifies the node. 49The actual name depends on the implementation. 50The framebuffer node would have a property with the name 51described by device bindings (device-specific set of properties). 52It can be a cell property or a combined property with one part 53of it being a cell. 54The value of the framebuffer node's property would be the same 55as the value of the GPIO "phandle" property so it can be said 56that the framebuffer node refers to the GPIO node. 57The kernel uses internal logic to assign unique identifiers 58to the device tree nodes, and these values do not match 59the values of "phandle" properties. 60.Fn OF_node_from_xref 61and 62.Fn OF_xref_from_node 63are used to perform conversion between these two kinds of node 64identifiers. 65.Pp 66.Fn OF_node_from_xref 67returns the kernel phandle for the effective phandle 68.Fa xref . 69If one cannot be found or the OpenFirmware implementation 70does not support effective phandles, the function returns 71the input value. 72.Pp 73.Fn OF_xref_from_xref 74returns the effective phandle for the kernel phandle 75.Fa xref . 76If one cannot be found or the OpenFirmware implementation 77does not support effective phandles, the function returns 78the input value. 79.Sh EXAMPLES 80.Bd -literal 81 phandle_t panelnode, panelxref; 82 char *model; 83 84 if (OF_getencprop(node, "lcd-panel", &panelxref) <= 0) 85 return; 86 87 panelnode = OF_node_from_xref(panelxref); 88 if (OF_getprop_alloc(hdminode, "model", (void **)&model) <= 0) 89 return; 90.Ed 91.Sh SEE ALSO 92.Xr OF_device_from_xref 9 , 93.Xr OF_device_register_xref 9 94.Sh AUTHORS 95.An -nosplit 96This manual page was written by 97.An Oleksandr Tymoshenko Aq Mt gonzo@FreeBSD.org . 98