CPU Fan control for 3C5000+7A2000

fanctl.c

/*
 ============================================================================
 Name        : fanctl.c
 Author      : hev <r@hev.cc>
 Copyright   : Copyright (c) 2023 hev
 Description : CPU Fan control for 3C5000+7A2000
 ============================================================================
 */

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

static FILE *fp;
static void *pwm;

static int
temp_init (void)
{
    fp = fopen ("/sys/class/hwmon/hwmon0/temp1_input", "r");
    if (!fp)
        return -1;

    return 0;
}

static void
temp_fini (void)
{
    fclose (fp);
}

static int
temp_read (void)
{
    char buf[32];
    int res;

    res = fseek (fp, 0, SEEK_SET);
    if (res < 0)
        return -1;

    res = fread (buf, sizeof (char), sizeof (buf) - 1, fp);
    if (res <= 0)
        return -1;

    buf[res] = '\0';
    return atoi (buf) / 1000;
}

static int
pwm_init (void)
{
    int fd;

    fd = open ("/dev/mem", O_RDWR | O_DSYNC);
    if (fd < 0)
        return -1;

    pwm = mmap (NULL, 16384, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
                0x100a0000UL);
    if (pwm == MAP_FAILED)
        return -2;

    close (fd);

    return 0;
}

static void
pwm_fini (void)
{
    munmap (pwm, 16384);
}

static void
pwm_set (int low, int full)
{
    /* disable */
    *(volatile unsigned int *)(pwm + 0xC) = 0;
    /* set low */
    *(volatile unsigned int *)(pwm + 0x4) = low;
    /* set full */
    *(volatile unsigned int *)(pwm + 0x8) = full;
    /* enable */
    *(volatile unsigned int *)(pwm + 0xC) = 1;
}

int
main (int argc, char *argv[])
{
    int res;

    res = pwm_init ();
    if (res < 0)
        return -1;

    res = temp_init ();
    if (res < 0)
        return -2;

    for (;;) {
        int temp;

        temp = temp_read ();

        switch (temp)
        {
        case 0 ... 15:
            pwm_set (9000, 10000);
            break;
        case 16 ... 20:
            pwm_set (8500, 10000);
            break;
        case 21 ... 25:
            pwm_set (8000, 10000);
            break;
        case 26 ... 30:
            pwm_set (7500, 10000);
            break;
        case 31 ... 35:
            pwm_set (7000, 10000);
            break;
        case 36 ... 40:
            pwm_set (6500, 10000);
            break;
        case 41 ... 45:
            pwm_set (6000, 10000);
            break;
        case 46 ... 50:
            pwm_set (5000, 10000);
            break;
        case 51 ... 55:
            pwm_set (4000, 10000);
            break;
        case 56 ... 60:
            pwm_set (3000, 10000);
            break;
        case 61 ... 65:
            pwm_set (2000, 10000);
            break;
        case 66 ... 70:
            pwm_set (1000, 10000);
            break;
        default:
            pwm_set (100, 10000);
            break;
        }

        sleep (1);
    }

    temp_fini ();
    pwm_fini ();

    return 0;
}