ben-blinkenlights/bbl/bbl.c

/*
 * bbl.c - Produce a "Knight Rider" effect on the LED board
 *
 * Written 2010-2011 by Werner Almesberger <werner@openmoko.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.
 */


#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/mman.h>


#define	GPIO_BASE		0x10010000

#define	REG(n)	(*(volatile uint32_t *) (mem+(n)-GPIO_BASE))

/*
 * The XBurst CPUs use an interesting concept for setting GPIOs: instead of
 * writing the value of a pin (0 or 1) directly to an output latch, the latch
 * is set by writing a 1 to a "set" register and cleared by writing a 1 to a
 * "clear" register. This way, only an atomic store but no atomic
 * read-modify-write operations are necessary for changing only part of the
 * bits on a port.
 *
 * The same set/clear mechanism is also used for the other writable registers
 * affecting GPIOs, e.g., the direction (input/output) and function (GPIO or
 * MMC) registers.
 */

#define	PDDATS	REG(0x10010314)	/* port D data set */
#define	PDDATC	REG(0x10010318)	/* port D data clear */
#define	PDFUNC	REG(0x10010348)	/* port D function clear */
#define	PDDIRS	REG(0x10010364)	/* port D direction set */
#define	PDDIRC	REG(0x10010368)	/* port D direction clear */

#define	LEDS		10	/* number of LEDs */

#define	GROUP_SEL	11	/* PD11, DAT1 - LED group selection */

#define	LED_MASK	0x3f00	/* all the LED groups and GROUP_SEL */

#define	DELAY_US	50000

#define PAGE_SIZE 4096

static volatile void *mem;


static int map(int group)
{
	switch (group) {
	case 0:
		return 12;	/* PD12, DAT2 */
	case 1:
		return 13;	/* PD13, DAT3/CD */
	case 2:
		return 8;	/* PD08, CMD */
	case 3:
		return 9;	/* PD09, CLK */
	case 4:
		return 10;	/* PD10, DAT0 */
	default:
		abort();
	}
}


static void set(int n)
{
	
	if (n & 1) {
		PDDATC = LED_MASK;
		PDDATS = 1 << map(n >> 1);
	} else {
		PDDATS = LED_MASK;
		PDDATC = 1 << map(n >> 1);
	}
}


static void die(int sig)
{
	PDDIRC = LED_MASK;	/* make all MMC pins inputs again */
	_exit(0);
}


int main(int argc, char **argv)
{
	int fd, i;

	fd = open("/dev/mem", O_RDWR | O_SYNC);
        if (fd < 0) {
		perror("/dev/mem");
		exit(1);
	}
	mem = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
	    GPIO_BASE);
	if (mem == MAP_FAILED) {
		perror("mmap");
		exit(1);
	}

	signal(SIGINT, die);

	PDFUNC = LED_MASK;	/* make all MMC pins GPIOs */
	PDDIRS = LED_MASK;	/* make all MMC pins outputs */

	while (1) {
		for (i = 0; i != LEDS-1; i++) {
			set(i);
			usleep(DELAY_US);
		}
		for (i = LEDS-1; i != 0; i--) {
			set(i);
			usleep(DELAY_US);
		}
	}
	return 0;
}