Enterprise Linux 6 - RHEL 6 (Santiago) - CentOS 6
remi-safe (only additonal packages for base repository)
remi (includes PHP 5.4, extensions and Software Collections)
Warning: some noarch packages may requires php 5.5 or greater (e.g. phpMyAdmin > 4.5)
so you may have to enable remi-php55 or remi-php56 to use these (but PHP 5.4 is EOL, so upgrade is recommended).