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>.