Support for PC Engines ALIX2 reset pushbutton.

Hello,

I've just written an user-space utility for handling the PC Enginges ALIX'
reset-pushbutton. It's a quick-and-dirty prototype and does the same what
"shutdown -h now" does. I'll do a clean rewrite later.

Any comments or suggestions appreciated.


Here is the prototype:

----- BEGIN -----

/*
 * User-space reset-button support for PC Engines ALIX boards.
 * This is a prototype.
 *
 * Usage:
 * Use from rc(8).
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/cdefs.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <machine/cpufunc.h>
#include <unistd.h>
#include <signal.h>
#include <sys/time.h>
#include <paths.h>
#include <syslog.h>

// MY_NAME is the process name used in syslog.
#define MY_NAME "resetguard"

// GPIO_RESET
u_int32_t switchAddr = 0x61b0;
int switchBit = 8;

// GPIO_LED3
u_int32_t ledAddr = 0x6180;
int ledBit = 11;


// Blink GPIO_LED3.
void blinkLed(int times)
{
	int i;

	for (i=0; i<times; i++)
	{
		outl(ledAddr, 1 << (ledBit + 16));
		usleep(80000);
		outl(ledAddr, 1 << ledBit);
		usleep(80000);
	}
}

// Return GPIO_RESET state.
char isResetPressed() {
    return ((inl(switchAddr) & (1 << switchBit)) == 0);
}

int main() {
    int fd;				// Define our file descriptor
    char *empty_environ[] = { NULL };	// Environment for halt(8)

    if(geteuid())
    {
	errx(1, "You're not super-user.");  // Show error and exit.
    }


    fd = open("/dev/io", O_RDONLY);	// Read-only file descriptor for /dev/io

    if (fd == -1) {			// On error (e.g. wrong permissions)
        perror("Cannot open /dev/io.");	// Print error message
        exit(1);			// and exit with status 1
    }

    /*
     *  At this point we'll be polling the GPIO-Pin of the Reset-button
     *  at the front of the PC Engines Alix board every 450ms.
     *  If the pin is HIGH, resetBoard() will be called.
     */

    while(1)			// Infinite loop
    {
        usleep(4000000);	// Wait ca. 450ms before probing again
	if(isResetPressed()) {	// If resetPressed() returns 1..
		blinkLed(4);		// Blink GPIO_LED3 4 times

		setlogmask(LOG_UPTO (LOG_NOTICE)); // LOG_NOTICE
		
		// We'll be logging to LOG_LOCAL1
		openlog(MY_NAME, LOG_CONS | LOG_NDELAY, LOG_LOCAL1);

		// Write message to syslog
		syslog(LOG_NOTICE, "Event detected on GPIO_RESET (UID %d)", getuid());

		// Close Log
		closelog();

		// Halt system (like "shutdown -h now" does)
		execle(_PATH_HALT, "halt", "-l", sync, (char *)NULL, empty_environ);

		// Exit with status 0
		exit(0);
	}
    }

    exit(0);			// This should never be reached (exit 0)
}


----- END -----