#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>

static int sys_cpu_setall(const char *control, const char *value);
static int sys_cpufreq_set(const char *control, const char *value);
static int sys_cpu_pstate(int min, int max, int turbo);

int
main(int argc, char *argv[])
{
   if (argc < 3)
     {
        fprintf(stderr, "Invalid command. Syntax:\n");
        fprintf(stderr, "\tcpuclock_sysfs <frequency|governor> <freq-level|governor-name>\n");
        fprintf(stderr, "\tcpuclock_sysfs <pstate> <min> <max> <turbo>\n");
        return 1;
     }

   if (seteuid(0))
     {
        fprintf(stderr, "%s %s\n", argv[0], argv[1]);
        fprintf(stderr, "Unable to assume root privileges\n");
        return 1;
     }
   if (!strcmp(argv[1], "frequency"))
     {
        if (sys_cpu_setall("scaling_setspeed", argv[2]) == 0)
          {
             fprintf(stderr, "Unable to open frequency interface for writing.\n");
             return 1;
          }

        return 0;
     }
   else if (!strcmp(argv[1], "governor"))
     {
        if (sys_cpu_setall("scaling_governor", argv[2]) == 0)
          {
             fprintf(stderr, "Unable to open governor interface for writing.\n");
             return 1;
          }
        if (!strcmp(argv[2], "ondemand"))
          sys_cpufreq_set("ondemand/ignore_nice_load", "0");
        else if (!strcmp(argv[2], "conservative"))
          sys_cpufreq_set("conservative/ignore_nice_load", "0");
        return 0;
     }
   else if (!strcmp(argv[1], "pstate"))
     {
        int min, max, turbo;

        if (argc < 5)
          {
             fprintf(stderr, "Invalid number of arguments.\n");
             return 1;
          }
        min = atoi(argv[2]);
        max = atoi(argv[3]);
        turbo = atoi(argv[4]);
        if ((min < 0) || (min > 100) ||
            (max < 0) || (max > 100) ||
            (turbo < 0) || (turbo > 1))
          {
             fprintf(stderr, "Invalid pstate values.\n");
             return 1;
          }
        sys_cpu_pstate(min, max, turbo);
        return 0;
     }
   else
     {
        fprintf(stderr, "Unknown command.\n");
        return 1;
     }

   return -1;
}

static int
sys_cpu_setall(const char *control, const char *value)
{
   int num = 0;
   char filename[4096];
   FILE *f;

   while (1)
     {
        snprintf(filename, sizeof(filename), "/sys/devices/system/cpu/cpu%i/cpufreq/%s", num, control);
        f = fopen(filename, "w");

        if (!f)
          {
             return num;
          }
        fprintf(f, "%s\n", value);
        fclose(f);
        num++;
     }
   return -1;
}

static int
sys_cpufreq_set(const char *control, const char *value)
{
   char filename[4096];
   FILE *f;

   snprintf(filename, sizeof(filename), "/sys/devices/system/cpu/cpufreq/%s", control);
   f = fopen(filename, "w");

   if (!f)
     {
        if (sys_cpu_setall(control, value) > 0)
          return 1;
        else
          return -1;
     }

   fprintf(f, "%s\n", value);
   fclose(f);

   return 1;
}

static int
sys_cpu_pstate(int min, int max, int turbo)
{
   FILE *f;

   f = fopen("/sys/devices/system/cpu/intel_pstate/min_perf_pct", "w");
   if (!f) return 0;
   fprintf(f, "%i\n", min);
   fclose(f);

   f = fopen("/sys/devices/system/cpu/intel_pstate/max_perf_pct", "w");
   if (!f) return 0;
   fprintf(f, "%i\n", max);
   fclose(f);

   f = fopen("/sys/devices/system/cpu/intel_pstate/no_turbo", "w");
   if (!f) return 0;
   fprintf(f, "%i\n", turbo ? 0 : 1);
   fclose(f);

   return 1;
}