1.\" $OpenBSD: dfs.4,v 1.2 2011/05/25 18:13:54 jmc Exp $ 2.\" 3.\" Copyright (c) 2011 Martin Pieuchot <mpi@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: May 25 2011 $ 18.Dt DFS 4 macppc 19.Os 20.Sh NAME 21.Nm dfs 22.Nd Dynamic Frequency Switching 23.Sh SYNOPSIS 24.Cd "dfs* at macgpio?" 25.Sh DESCRIPTION 26The 27.Nm 28driver provides support for the Dynamic Frequency Switching 29feature found on some PowerPC microprocessors. 30.Pp 31It conserves power by lowering the processor operating frequency. 32Depending on the processor model, the processor-to-system bus ratio can 33be divided by two or four. 34.Sh HARDWARE 35Processors supported by the 36.Nm 37driver are part of the PowerPC G4 family and are found on various iBook 38and PowerBook machines: 39.Bd -literal -offset indent 40MPC7447A PowerPC 7447 "Apollo 7" 41MPC7448 PowerPC 7448 "Apollo 8" 42.Ed 43.Sh SEE ALSO 44.Xr macgpio 4 , 45.Xr sysctl 8 46.Rs 47.%T MPC7450 RISC Microprocessor Family Reference Manual 48.Re 49.Sh HISTORY 50Support for the 51.Nm 52driver first appeared in 53.Ox 5.0 . 54