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26.\" $FreeBSD$
27.\"
28.Dd April 9, 2018
29.Dt OF_DEVICE_FROM_XREF 9
30.Os
31.Sh NAME
32.Nm OF_device_from_xref ,
33.Nm OF_xref_from_device ,
34.Nm OF_device_register_xref
35.Nd "manage mappings between xrefs and devices"
36.Sh SYNOPSIS
37.In dev/ofw/ofw_bus.h
38.In dev/ofw/ofw_bus_subr.h
39.Ft int
40.Fn OF_device_register_xref "phandle_t xref" "device_t dev"
41.Ft device_t
42.Fn OF_device_from_xref "phandle_t xref"
43.Ft phandle_t
44.Fn OF_xref_from_device "device_t dev"
45.Sh DESCRIPTION
46When a device tree node references another node, the driver may
47need to get a device_t instance associated with the referenced node.
48For instance, an Ethernet driver accessing a PHY device.
49To make this possible, the kernel maintains a table that
50maps effective handles to device_t instances.
51.Pp
52.Fn OF_device_register_xref
53adds a map entry from the effective phandle
54.Fa xref
55to device
56.Fa dev .
57If a mapping entry for
58.Fa xref
59already exists, it is replaced with the new one.
60The function always returns 0.
61.Pp
62.Fn OF_device_from_xref
63returns a device_t instance associated with the effective phandle
64.Fa xref .
65If no such mapping exists, the function returns NULL.
66.Pp
67.Fn OF_xref_from_device
68returns the effective phandle associated with the device
69.Fa dev .
70If no such mapping exists, the function returns 0.
71.Sh EXAMPLES
72.Bd -literal
73    static int
74    acmephy_attach(device_t dev)
75    {
76        phandle_t node;
77
78	/* PHY node is referenced from eth device, register it */
79        node = ofw_bus_get_node(dev);
80        OF_device_register_xref(OF_xref_from_node(node), dev);
81
82        return (0);
83    }
84.Ed
85.Sh SEE ALSO
86.Xr OF_node_to_xref 9
87.Sh AUTHORS
88.An -nosplit
89This manual page was written by
90.An Oleksandr Tymoshenko Aq Mt gonzo@FreeBSD.org .
91