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.\" $FreeBSD$ 27.\" 28.Dd April 9, 2018 29.Dt OF_NODE_FROM_XREF 9 30.Os 31.Sh NAME 32.Nm OF_node_from_xref , 33.Nm OF_xref_from_node 34.Nd convert between kernel phandle and effective phandle 35.Sh SYNOPSIS 36.In dev/ofw/ofw_bus.h 37.In dev/ofw/ofw_bus_subr.h 38.Ft phandle_t 39.Fn OF_node_from_xref "phandle_t xref" 40.Ft phandle_t 41.Fn OF_xref_from_node "phandle_t node" 42.Sh DESCRIPTION 43.Pp 44Some OpenFirmware implementations (FDT, IBM) have a concept 45of effective phandle or xrefs. 46They are used to cross-reference device tree nodes. 47For instance, a framebuffer controller may refer to a GPIO 48controller and pin that controls the backlight. 49In this example, the GPIO node would have a cell (32-bit integer) 50property with a reserved name like "phandle" or "linux,phandle" 51whose value uniquely identifies the node. 52The actual name depends on the implementation. 53The framebuffer node would have a property with the name 54described by device bindings (device-specific set of properties). 55It can be a cell property or a combined property with one part 56of it being a cell. 57The value of the framebuffer node's property would be the same 58as the value of the GPIO "phandle" property so it can be said 59that the framebuffer node refers to the GPIO node. 60The kernel uses internal logic to assign unique identifiers 61to the device tree nodes, and these values do not match 62the values of "phandle" properties. 63.Fn OF_node_from_xref 64and 65.Fn OF_xref_from_node 66are used to perform conversion between these two kinds of node 67identifiers. 68.Pp 69.Fn OF_node_from_xref 70returns the kernel phandle for the effective phandle 71.Fa xref . 72If one cannot be found or the OpenFirmware implementation 73does not support effective phandles, the function returns 74the input value. 75.Pp 76.Fn OF_xref_from_xref 77returns the effective phandle for the kernel phandle 78.Fa xref . 79If one cannot be found or the OpenFirmware implementation 80does not support effective phandles, the function returns 81the input value. 82.Sh EXAMPLES 83.Bd -literal 84 phandle_t panelnode, panelxref; 85 char *model; 86 87 if (OF_getencprop(node, "lcd-panel", &panelxref) <= 0) 88 return; 89 90 panelnode = OF_node_from_xref(panelxref); 91 if (OF_getprop_alloc(hdminode, "model", (void **)&model) <= 0) 92 return; 93.Ed 94.Sh SEE ALSO 95.Xr OF_device_from_xref 9 96.Xr OF_device_register_xref 9 97.Sh AUTHORS 98.An -nosplit 99This manual page was written by 100.An Oleksandr Tymoshenko Aq Mt gonzo@FreeBSD.org . 101