OF_DEVICE_FROM_XREF(9)                       FreeBSD Kernel Developer's Manual

NAME
     OF_device_from_xref, OF_xref_from_device, OF_device_register_xref -
     manage mappings between xrefs and devices

SYNOPSIS
     #include <dev/ofw/ofw_bus.h>
     #include <dev/ofw/ofw_bus_subr.h>

     int
     OF_device_register_xref(phandle_t xref, device_t dev);

     device_t
     OF_device_from_xref(phandle_t xref);

     phandle_t
     OF_xref_from_device(device_t dev);

DESCRIPTION
     When a device tree node references another node, the driver may need to
     get a device_t instance associated with the referenced node.  For
     instance, an Ethernet driver accessing a PHY device.  To make this
     possible, the kernel maintains a table that maps effective handles to
     device_t instances.

     OF_device_register_xref() adds a map entry from the effective phandle
     xref to device dev.  If a mapping entry for xref already exists, it is
     replaced with the new one.  The function always returns 0.

     OF_device_from_xref() returns a device_t instance associated with the
     effective phandle xref.  If no such mapping exists, the function returns
     NULL.

     OF_xref_from_device() returns the effective phandle associated with the
     device dev.  If no such mapping exists, the function returns 0.

EXAMPLES
         static int
         acmephy_attach(device_t dev)
         {
             phandle_t node;

             /* PHY node is referenced from eth device, register it */
             node = ofw_bus_get_node(dev);
             OF_device_register_xref(OF_xref_from_node(node), dev);

             return (0);
         }

SEE ALSO
     OF_node_to_xref(9)

AUTHORS
     This manual page was written by Oleksandr Tymoshenko <gonzo@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6          April 9, 2018         FreeBSD 13.1-RELEASE-p6