160 lines
3.9 KiB
Groff
160 lines
3.9 KiB
Groff
.\" Copyright (c) 2003 Poul-Henning Kamp <phk@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 23, 2003
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.Dt CPU_ELAN 4 i386
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.Os
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.Sh NAME
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.Nm CPU_ELAN
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.Nd AMD Elan 520 CPU support
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.Sh SYNOPSIS
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.Cd "options CPU_ELAN"
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.Cd "options CPU_ELAN_PPS"
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.Cd "options CPU_ELAN_XTAL"
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.Bl -item -compact
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.It
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.Va machdep.elan_gpio_config
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.It
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.Va machdep.elan_freq
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.El
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.Cd "options CPU_SOEKRIS"
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.Sh DESCRIPTION
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The
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.Cd "options CPU_ELAN"
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enables support for the AMD Elan 520 CPU.
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.Pp
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A device
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.Pa /dev/elan-mmcr
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exports the MMCR register bank to userland
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using
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.Xr mmap 2 .
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.Pp
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The
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.Tn i8254
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timer will be adjusted to the slightly unorthodox
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frequency 1189161 Hz (32768 * 45 * 25 / 31) employed by the Elan.
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.Pp
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A timecounter named
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.Dq Li ELAN
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is implemented using the general purpose timer 2,
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but it will not be usable unless HZ is configured at 150 or higher.
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This timecounter is much better than the
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.Dq Li i8254
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timecounter and should be
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used at all times.
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.Pp
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The
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.Va machdep.elan_gpio_config
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.Xr sysctl 8
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variable
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enables configuration of the GPIO pins of the CPU.
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The string must be exactly 32 characters long.
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A
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.Ql -
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means the GPIO is unavailable.
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A
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.Ql l
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(lower-case ell) configures a
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.Xr led 4
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device (active low).
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A
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.Ql L
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configures a
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.Xr led 4
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device (active high).
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A
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.Ql \&.
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means no configuration for this GPIO.
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These
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.Xr led 4
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devices will be named
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.Pa /dev/led/gpio%d .
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For meaning of
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.Ql P ,
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.Ql e
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and
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.Ql E ,
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see under
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.Cd "options CPU_ELAN_PPS" .
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.Pp
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The
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.Cd "options CPU_ELAN_XTAL"
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and the
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.Va machdep.elan_freq
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.Xr sysctl 8
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variable
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can be used to set the CPU clock crystal frequency in Hz.
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The default is 33333333 Hz.
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.Pp
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The
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.Cd "options CPU_ELAN_PPS"
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enables precision timestamping using the RFC2783 PPS-API via the
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.Pa /dev/elan-mmcr
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device.
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The resolution will be approximately 125 nsec
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and the precision \(+- 125 nsec.
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(For 125 nsec read
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.Dq "4 / CPU clock crystal frequency" . )
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.Pp
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The input signal must be connected to the TMR1IN pin and
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a GPIO pin.
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The GPIO pin must be configured with a
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.Ql P
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in
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.Va machdep.elan_gpio_config .
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.Pp
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In addition, one GPIO pin can be configured with either
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.Ql e
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(active low)
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or
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.Ql E
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(active high) to become a
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.Dq echo
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output of the input signal.
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Please notice that this signal is not suitable for calibration.
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.Pp
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If the
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.Cd "options CPU_SOEKRIS"
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is given, the support will additionally be tailored to the
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Soekris Engineering 45xx series of embedded computers.
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The
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.Dq error
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led will be configured (as
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.Pa /dev/led/error )
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and the GPIO pins which are not
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available will be disabled.
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.Sh SEE ALSO
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.Xr led 4 ,
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.Xr timecounters 4 ,
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.Xr sysctl 8
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.Sh HISTORY
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The
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.Nm
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code first appeared in
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.Fx 4.7 .
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.Sh AUTHORS
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.An "Poul-Henning Kamp" Aq phk@FreeBSD.org
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