/*
 * Apple Macbook Pro LCD backlight control
 *
 * Copyright (C) 2006 Nicolas Boichat <nicolas@boichat.ch>
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <stdio.h>
#include <sys/io.h>
#include <stdlib.h>

int main(int argc, char** argv) {
	int value = -1;

	if (argc > 2) {
		printf("Usage:\n");
		printf("%s : read current value\n", argv[0]);
		printf("%s value : write value [0-15]\n", argv[0]);
	}
	
	if (argc == 2) {
		value = atoi(argv[1]);
		if ((value < 0) || (value > 15)) {
			printf("Invalid value (should be between 0 and 15).\n");
			exit(0);
		}
	}
	
	if (ioperm(0xB2, 0xB3, 1) < 0) {
		perror("ioperm failed (you should be root).");
		exit(1);
	}

	if (value < 0) {
		outb(0x03, 0xB3);
		outb(0xBF, 0xB2);
		char t = inb(0xB3) >> 4;
		printf("Current value : %d\n", t);
	}
	else {
		outb(0x04 | (value << 4), 0xB3);
		outb(0xBF, 0xB2);
	}

	return 0;
}