// SPDX-License-Identifier: GPL-2.0
#include <math.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/timeb.h>
#include <sched.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include "kselftest.h"

#define MSEC_PER_SEC    1000L
#define NSEC_PER_MSEC   1000000L

void usage(char *name) {
        printf ("Usage: %s cpunum\n", name);
}

int main(int argc, char **argv) {
        unsigned int i, cpu, fd;
        char msr_file_name[64];
        long long tsc, old_tsc, new_tsc;
        long long aperf, old_aperf, new_aperf;
        long long mperf, old_mperf, new_mperf;
        struct timespec before, after;
        long long int start, finish, total;
        cpu_set_t cpuset;

        if (argc != 2) {
                usage(argv[0]);
                return 1;
        }

        errno = 0;
        cpu = strtol(argv[1], (char **) NULL, 10);

        if (errno) {
                usage(argv[0]);
                return 1;
        }

        sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
        fd = open(msr_file_name, O_RDONLY);

        if (fd == -1) {
                printf("/dev/cpu/%d/msr: %s\n", cpu, strerror(errno));
                return KSFT_SKIP;
        }

        CPU_ZERO(&cpuset);
        CPU_SET(cpu, &cpuset);

        if (sched_setaffinity(0, sizeof(cpu_set_t), &cpuset)) {
                perror("Failed to set cpu affinity");
                return 1;
        }

        if (clock_gettime(CLOCK_MONOTONIC, &before) < 0) {
                perror("clock_gettime");
                return 1;
        }
        pread(fd, &old_tsc,  sizeof(old_tsc), 0x10);
        pread(fd, &old_aperf,  sizeof(old_mperf), 0xe7);
        pread(fd, &old_mperf,  sizeof(old_aperf), 0xe8);

        for (i=0; i<0x8fffffff; i++) {
                sqrt(i);
        }

        if (clock_gettime(CLOCK_MONOTONIC, &after) < 0) {
                perror("clock_gettime");
                return 1;
        }
        pread(fd, &new_tsc,  sizeof(new_tsc), 0x10);
        pread(fd, &new_aperf,  sizeof(new_mperf), 0xe7);
        pread(fd, &new_mperf,  sizeof(new_aperf), 0xe8);

        tsc = new_tsc-old_tsc;
        aperf = new_aperf-old_aperf;
        mperf = new_mperf-old_mperf;

        start = before.tv_sec*MSEC_PER_SEC + before.tv_nsec/NSEC_PER_MSEC;
        finish = after.tv_sec*MSEC_PER_SEC + after.tv_nsec/NSEC_PER_MSEC;
        total = finish - start;

        printf("runTime: %4.2f\n", 1.0*total/MSEC_PER_SEC);
        printf("freq: %7.0f\n", tsc / (1.0*aperf / (1.0 * mperf)) / total);
        return 0;
}