root/i2c-tools/trunk/eeprom/decode-edid

#!/usr/bin/perl -w
#
# Copyright (C) 2003-2006 Jean Delvare <khali@linux-fr.org>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#    MA 02110-1301 USA.
#
# Version 0.1  2003-07-17  Jean Delvare <khali@linux-fr.org>
# Version 0.2  2003-07-22  Jean Delvare <khali@linux-fr.org>
#  Use print instead of syswrite.
# Version 0.3  2003-08-24  Jean Delvare <khali@linux-fr.org>
#  Fix data block length (128 bytes instead of 256).
# Version 1.0  2004-02-08  Jean Delvare <khali@linux-fr.org>
#  Added support for Linux 2.5/2.6 (i.e. sysfs).
# Version 1.1  2006-09-01  Jean Delvare <khali@linux-fr.org>
#  Append /usr/sbin or /usr/local/sbin to $PATH if needed.
#
# EEPROM data decoding for EDID. EDID (Extended Display Identification
# Data) is a VESA standard which allows storing (on manufacturer's side)
# and retrieving (on user's side) of configuration information about
# displays, such as manufacturer, serial number, physical dimensions and
# allowed horizontal and vertical refresh rates.
#
# Using the eeprom kernel driver, you have two possibilities to
# make use of these data:
#  1* The ddcmon script.
#  2* This script.
# Both solutions will return a different kind of information. The first
# method will report user-interesting information, such as the model number
# or the year of manufacturing. The second method will report video-card-
# interesting information, such as video modes and refresh rates.
#
# Note that this script does almost nothing by itself. It simply converts
# what it finds in /proc to binary data to feed the parse-edid program.
# The parse-edid program was written by John Fremlin and is available at
# the following address:
#   http://john.fremlin.de/programs/linux/read-edid/

use strict;
use Fcntl qw(:DEFAULT :seek);
use vars qw($bus $address);
use constant PROCFS => 1;
use constant SYSFS  => 2;

# parse-edid will typically be installed in /usr/sbin or /usr/local/sbin
# even though regular users can run it
$ENV{PATH} .= ':/usr/local/sbin'
        if $ENV{PATH} !~ m,(^|:)/usr/local/sbin/?(:|$),
        && -x '/usr/local/sbin/parse-edid';
$ENV{PATH} .= ':/usr/sbin'
        if $ENV{PATH} !~ m,(^|:)/usr/sbin/?(:|$),
        && -x '/usr/sbin/parse-edid';

sub edid_valid_procfs
{
        my ($bus, $addr) = @_;

        open EEDATA, "/proc/sys/dev/sensors/eeprom-i2c-$bus-$addr/00";
        my $line = <EEDATA>;
        close EEDATA;
        return 1
                if $line =~ m/^0 255 255 255 255 255 255 0 /;
        return 0;
}

# Only used for sysfs
sub rawread
{
        my ($filename, $length, $offset) = @_;
        my $bytes = '';

        sysopen(FH, $filename, O_RDONLY)
                or die "Can't open $filename";
        if ($offset)
        {
                sysseek(FH, $offset, SEEK_SET)
                        or die "Can't seek in $filename";
        }

        $offset = 0;
        while ($length)
        {
                my $r = sysread(FH, $bytes, $length, $offset);
                die "Can't read $filename"
                        unless defined($r);
                die "Unexpected EOF in $filename"
                        unless $r;
                $offset += $r;
                $length -= $r;
        }
        close(FH);

        return $bytes;
}

sub edid_valid_sysfs
{
        my ($bus, $addr) = @_;
        my $bytes = rawread("/sys/bus/i2c/devices/$bus-00$addr/eeprom", 8, 0);

        return 1
                if $bytes eq "\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00";
        return 0;
}

sub bus_detect
{
        my $max = shift;

        for (my $i=0; $i<$max; $i++)
        {
                if (-r "/proc/sys/dev/sensors/eeprom-i2c-$i-50/00")
                {
                        if (edid_valid_procfs($i, '50'))
                        {
                                print STDERR
                                        "decode-edid: using bus $i (autodetected)\n";
                                return $i;
                        }
                }
                elsif (-r "/sys/bus/i2c/devices/$i-0050/eeprom")
                {
                        if (edid_valid_sysfs($i, '50'))
                        {
                                print STDERR
                                        "decode-edid: using bus $i (autodetected)\n";
                                return $i;
                        }
                }
        }

        return; # default
}

sub edid_decode
{
        my ($bus, $addr, $mode) = @_;

        # Make sure it is an EDID EEPROM.

        unless (($mode == PROCFS && edid_valid_procfs ($bus, $addr))
             || ($mode == SYSFS  && edid_valid_sysfs  ($bus, $addr)))
        {
                print STDERR
                        "decode-edid: not an EDID EEPROM at $bus-$addr\n";
                return;
        }

        $SIG{__WARN__} = sub { };
        open PIPE, "| parse-edid"
                or die "Can't open parse-edid. Please install read-edid.\n";
        delete $SIG{__WARN__};
        binmode PIPE;

        if ($mode == PROCFS)
        {
                for (my $i=0; $i<=0x70; $i+=0x10)
                {
                        my $file = sprintf '%02x', $i;
                        my $output = '';
                        open EEDATA, "/proc/sys/dev/sensors/eeprom-i2c-$bus-$addr/$file"
                                or die "Can't read /proc/sys/dev/sensors/eeprom-i2c-$bus-$addr/$file";
                        while(<EEDATA>)
                        {
                                foreach my $item (split)
                                {
                                        $output .= pack "C", $item;
                                }
                        }
                        close EEDATA;
                        print PIPE $output;
                }
        }
        elsif ($mode == SYSFS)
        {
                print PIPE rawread("/sys/bus/i2c/devices/$bus-00$address/eeprom", 128, 0);
        }

        close PIPE;
}

# Get the address. Default to 0x50 if not given.
$address = $ARGV[1] || 0x50;
# Convert to decimal, whatever the value.
$address = oct $address if $address =~ m/^0/;
# Convert to an hexadecimal string.
$address = sprintf '%02x', $address;

# Get the bus. Try to autodetect if not given.
$bus = $ARGV[0] if defined $ARGV[0];
$bus = bus_detect(8) unless defined $bus;

if(defined $bus)
{
        print STDERR
                "decode-edid: decode-edid version 1.1\n";
        if (-r "/proc/sys/dev/sensors/eeprom-i2c-$bus-$address")
        {
                edid_decode ($bus, $address, PROCFS);
                exit 0;
        }
        elsif (-r "/sys/bus/i2c/devices/$bus-00$address")
        {
                edid_decode ($bus, $address, SYSFS);
                exit 0;
        }
}

print STDERR
        "EDID EEPROM not found.  Please make sure that the eeprom module is loaded.\n";
print STDERR
        "Maybe your EDID EEPROM is on another bus.  Try \"decode-edid ".($bus+1)."\".\n"
        if defined $bus;