b22750720f
.Sh "SEE ALSO" to: .Sh SEE ALSO The doc macros check for the latter (actually just for 'SEE' as the first argument to .Sh) to set the section header SEE ALSO flag, which modifies some behaviour (e.g. references done with .Rs/.Re).
119 lines
4.2 KiB
Groff
119 lines
4.2 KiB
Groff
.\" $NetBSD: leds.4,v 1.5 1999/04/06 04:54:20 cgd Exp $
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.\"
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.\" Copyright (c) 1997 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by der Mouse and Jeremy Cooper.
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd March 2, 1996
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.Dt LEDS 4 sun3
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.Os
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.Sh NAME
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.Nm leds
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.Nd sun3 diagnostic Light Emitting Diodes driver
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.Sh SYNOPSIS
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.nf
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.ft B
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#include <machine/leds.h>
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.ft R
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.fi
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.Sh DESCRIPTION
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With the exception of the Sun 3/80, all sun3 machines are equipped
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a diagnostic display of eight Light Emitting Diodes (LEDs), located
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on the back of the system unit.
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The Sun 3/80 has a single LED, which is located on the front panel.
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.Pp
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The kernel changes the display during periods of idle processor activity
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according to a stored sequential pattern list.
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The
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.Pa /dev/leds
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interface provides a way of manipulating the pattern list via simple file I/O.
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.Pp
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The structure of the file is as follows:
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.Bd -literal
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struct led_patterns {
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u_char divisor;
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u_char patlen;
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u_char pat[256];
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};
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.Ed
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.Bl -tag -width divisor
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.It Sy divisor
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The number of idle periods to wait before switching to the next pattern in
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the array.
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.It Sy patlen
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The number of patterns stored in the array.
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.It Sy pat
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The array of patterns to display.
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.El
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.Pp
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When a clock interrupt occurs while the processor is idle, a pattern
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countdown timer is decremented.
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When the countdown timer reaches zero
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it is reset with the
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.Sy divisor
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value and the next pattern in the array is selected and displayed.
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.Pp
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Each 8-bit pattern describes the state of the diagnostic LEDs.
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With the exception of the 3/80, a set bit in a pattern indicates that its
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corresponding LED should be be extinguished,
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while a reset bit indicates an LED to be illuminated.
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On the 3/80 the polarity of the bits is reversed and only the lowest order bit
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is used.
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.Sh EXAMPLES
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The following example uses
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.Xr awk 1
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to display the repeating animation of a single lit LED scrolling from one end
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of the display to the other, using six clock ticks between each update.
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.Bd -ragged -offset -ident
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# echo 5 8 254 253 250 247 239 223 191 127 |
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awk '{ for (i=1;i<=NF;i++) printf("%c",$i+0); }' > /dev/leds
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.Ed
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.Sh "ERRORS"
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An I/O transfer to
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.Pa /dev/leds
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will complete successfully unless:
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.Bl -tag -width Er
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.It Bq Er EIO
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A read or write starting beyond the end of the file was attempted.
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.El
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.Sh FILES
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.Bl -tag -width /dev/leds -compact
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.It Pa /dev/leds
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.El
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.Sh SEE ALSO
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.Xr ppt 6
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.Sh HISTORY
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.Pa /dev/leds
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first appeared in
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.Nx 1.2 .
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