1c45456fbSAlexander Motin.\" Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org> 2c45456fbSAlexander Motin.\" All rights reserved. 3c45456fbSAlexander Motin.\" 4c45456fbSAlexander Motin.\" Redistribution and use in source and binary forms, with or without 5c45456fbSAlexander Motin.\" modification, are permitted provided that the following conditions 6c45456fbSAlexander Motin.\" are met: 7c45456fbSAlexander Motin.\" 1. Redistributions of source code must retain the above copyright 8c45456fbSAlexander Motin.\" notice, this list of conditions and the following disclaimer. 9c45456fbSAlexander Motin.\" 2. Redistributions in binary form must reproduce the above copyright 10c45456fbSAlexander Motin.\" notice, this list of conditions and the following disclaimer in the 11c45456fbSAlexander Motin.\" documentation and/or other materials provided with the distribution. 12c45456fbSAlexander Motin.\" 13c45456fbSAlexander Motin.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14c45456fbSAlexander Motin.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15c45456fbSAlexander Motin.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16c45456fbSAlexander Motin.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17c45456fbSAlexander Motin.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18c45456fbSAlexander Motin.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19c45456fbSAlexander Motin.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20c45456fbSAlexander Motin.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21c45456fbSAlexander Motin.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22c45456fbSAlexander Motin.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23c45456fbSAlexander Motin.\" SUCH DAMAGE. 24c45456fbSAlexander Motin.\" 25*224f3a53SMichael Gmelin.Dd December 15, 2022 26a6d11f71SRuslan Ermilov.Dt ATRTC 4 27c45456fbSAlexander Motin.Os 28c45456fbSAlexander Motin.Sh NAME 29c45456fbSAlexander Motin.Nm atrtc 30c45456fbSAlexander Motin.Nd AT Real-Time Clock (RTC) driver 31c45456fbSAlexander Motin.Sh SYNOPSIS 32c45456fbSAlexander MotinThis driver is a mandatory part of i386/amd64 kernels. 33c45456fbSAlexander Motin.Pp 344a6d4e7bSRoger Pau MonnéThe following tunables are settable from the 35c45456fbSAlexander Motin.Xr loader 8 : 36c45456fbSAlexander Motin.Bl -ohang 37c45456fbSAlexander Motin.It Va hint.atrtc. Ns Ar X Ns Va .clock 3825972509SEdward Tomasz Napieralacontrols event timers functionality support. 3925972509SEdward Tomasz NapieralaSetting to 0, disables it. 40c45456fbSAlexander MotinDefault value is 1. 41*224f3a53SMichael Gmelin.It Va hw.atrtc.enabled 424a6d4e7bSRoger Pau MonnéForces enabling or disabling of the device(s). 434a6d4e7bSRoger Pau MonnéSetting to 0 disables it, setting to 1 enables it, bypassing any platform 444a6d4e7bSRoger Pau Monnéconfiguration hints. 454a6d4e7bSRoger Pau MonnéDefault value is -1 (autodetect). 46c45456fbSAlexander Motin.El 47c45456fbSAlexander Motin.Sh DESCRIPTION 48c45456fbSAlexander MotinThis driver uses RTC hardware to supply kernel with time-of-day clock 49c45456fbSAlexander Motinwith 1 second resolution and one event timer. 50c45456fbSAlexander MotinThis hardware uses base frequency of 32768Hz for advancing time-of-day clock 51c45456fbSAlexander Motinand generating periodic interrupts. 52c45456fbSAlexander MotinInterrupts could be generated with fixed number of frequencies, from 2Hz to 53c45456fbSAlexander Motin8192Hz, obtained by dividing base frequency by one of supported power-of-2 54c45456fbSAlexander Motindivisors. 55c45456fbSAlexander Motin.Pp 56c45456fbSAlexander MotinEvent timer provided by the driver is irrelevant to CPU power states. 57c45456fbSAlexander Motin.Sh SEE ALSO 5873889c80SAlexander Motin.Xr apic 4 , 59c45456fbSAlexander Motin.Xr attimer 4 , 6073889c80SAlexander Motin.Xr eventtimers 4 , 6173889c80SAlexander Motin.Xr hpet 4 62