use Text::CSV_XS; # which is maintained by jZed and well loved by all

# Read it as a handle w/ binary if newlines might be embedded in your data
my $csv = Text::CSV_XS->new( binary => 1 );
open my $fh, \ $your_string;
while ( my $columns = $csv->getline( $fh ) ) {
    ...
}

# Or just read it like a string if you never have newlines inside a value.
while ( $str =~ /(.+)/g ) {
    my $line = $1;
    my $columns = $csv->parse( $line );
}