xref: /freebsd/share/man/man9/device_get_softc.9 (revision 06c3fb27)
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29.Dd January 21, 2015
30.Dt DEVICE_GET_SOFTC 9
31.Os
32.Sh NAME
33.Nm device_get_softc
34.Nd access driver private instance variables
35.Sh SYNOPSIS
36.In sys/param.h
37.In sys/bus.h
38.Ft void *
39.Fn device_get_softc "device_t dev"
40.Sh DESCRIPTION
41Return the driver-specific software context of
42.Fa dev .
43The softc is automatically allocated and zeroed when the device is
44attached.
45The softc is also initialized and present when a device is probed,
46but is subject to caveats as described in
47.Xr DEVICE_PROBE 9 .
48The size of the allocation is determined by the device's
49.Vt driver_t
50information used to define the driver.
51The softc typically encapsulates the state of this instance of the
52device.
53.Pp
54Driver writers are discouraged from using their own softc management
55mechanisms.
56Driver writers should not copy such mechanisms found in drivers in the
57tree that predate this function.
58.Sh RETURN VALUES
59The pointer to the driver-specific instance variable is returned.
60.Sh SEE ALSO
61.Xr device 9 ,
62.Xr DEVICE_PROBE 9 ,
63.Xr device_set_softc 9 ,
64.Xr driver 9
65.Sh AUTHORS
66This manual page was written by
67.An Doug Rabson .
68