#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <machine/cpufunc.h>
#include <unistd.h>

#define VPERLSB 0.008
#define MAXDIG (VPERLSB * 256)

#define WB_ADR	0x5
#define WB_DATA	0x6

void
usage(char *name) {
    fprintf(stderr,
	    "Bad usage\n"
	    "\t%s [-b base]\n"
	    "\n"
	    "Read/write registers in Winbond SuperIO parts\n"
	    "base is the base address for the chip (default: 0x290)\n"
	    "adr is the register to read/write\n"
	    "data is the data to write to adr\n", name);
    exit(1);
}

int
readwb(int base, int adr) {
    /* Register to access */
    outb(base + WB_ADR, adr);

    return(inb(base + WB_DATA));
}

void
writewb(int base, int adr, int val) {
    /* Register to access */
    outb(base + WB_ADR, adr);

    outb(base + WB_DATA, val);
}

float
raw2volt(int val, float r1, float r2) {
    float digval, result;
    
    digval = val * VPERLSB;
    result = digval * ((r1 + r2) / r2);
    return(result);
}

float
raw2negvolt(int val, float r1, float r2) {
    return((val * 0.008 - 2.048)/(r2 / (r1 + r2))) + 2.048;
}

float
raw2rpm(int val, int divisor) {
    return(1360000 / (float)(val) / divisor);
}

int
raw2divisor(int val) {
    return(1 << val);
}

int
main(int argc, char **argv) {
    int	fd, base, ch, tmp;
    char *progname;
    
    base = 0x290;
    
    progname = argv[0];
    
    while ((ch = getopt(argc, argv, "b:")) != -1) {
	switch (ch) {
	    case 'b':
		base = strtol(optarg, NULL, 0) & 0xffff;
		break;
		    
	    default:
		usage(progname);
		break;
	}
    }
    argc -= optind;
    argv += optind;
	
    if ((fd = open("/dev/io", O_RDWR)) == -1) {
	fprintf(stderr, "Can't open /dev/io: %s\n", strerror(errno));
	exit(1);
    }

    printf("3V3 = %.2f V\n", raw2volt(readwb(base, 0x23), 34000, 34000));
    printf("-12V = %.2f V\n", raw2negvolt(readwb(base, 0x26), 232000, 10000));
    tmp = (readwb(base, 0x47) & 0xc0) >> 6;
    tmp |= (readwb(base, 0x5d) & 0x40) >> 4;
    tmp = raw2divisor(tmp);
    printf("CPU fan = %.0f rpm (divisor %d)\n", raw2rpm(readwb(base, 0x29), tmp), tmp);
    exit(0);
}