/*
 * Copyright (c) 2004-2007 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2014 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * Copyright (c) 2015      Research Organization for Information Science
 *                         and Technology (RIST). All rights reserved.
 * $COPYRIGHT$
 * 
 * Additional copyrights may follow
 * 
 * $HEADER$
 */

#include "opal_config.h"

#ifdef HAVE_STRING_H
#include <string.h>
#endif

#include "opal/mca/timer/timer.h"
#include "opal/mca/timer/base/base.h"
#include "opal/mca/timer/linux/timer_linux.h"
#include "opal/constants.h"

static opal_timer_t opal_timer_base_get_cycles_sys_timer(void);
static opal_timer_t opal_timer_base_get_usec_sys_timer(void);

#if OPAL_HAVE_CLOCK_GETTIME
static opal_timer_t opal_timer_base_get_cycles_clock_gettime(void);
static opal_timer_t opal_timer_base_get_usec_clock_gettime(void);
opal_timer_t (*opal_timer_base_get_cycles)(void) = opal_timer_base_get_cycles_clock_gettime;
opal_timer_t (*opal_timer_base_get_usec)(void) = opal_timer_base_get_usec_clock_gettime;
#else
opal_timer_t (*opal_timer_base_get_cycles)(void) = opal_timer_base_get_cycles_sys_timer;
opal_timer_t (*opal_timer_base_get_usec)(void) = opal_timer_base_get_usec_sys_timer;
#endif  /* OPAL_HAVE_CLOCK_GETTIME */

opal_timer_t opal_timer_linux_freq;

static int opal_timer_linux_open(void);

const opal_timer_base_component_2_0_0_t mca_timer_linux_component = {
    /* First, the mca_component_t struct containing meta information
       about the component itself */
    {
        OPAL_TIMER_BASE_VERSION_2_0_0,

        /* Component name and version */
        "linux",
        OPAL_MAJOR_VERSION,
        OPAL_MINOR_VERSION,
        OPAL_RELEASE_VERSION,

        /* Component open and close functions */
        opal_timer_linux_open,
        NULL
    },
    {
        /* The component is checkpoint ready */
        MCA_BASE_METADATA_PARAM_CHECKPOINT
    },
};

static char *
find_info(FILE* fp, char *str, char *buf, size_t buflen)
{
    char *tmp;

    rewind(fp);
    while (NULL != fgets(buf, buflen, fp)) {
        if (strncmp(buf, str, strlen(str)) == 0) {
            /* we found the line.  Now eat everything up to,
               including, and one past the : */
            for (tmp = buf ; (*tmp != '\0') && (*tmp != ':') ; ++tmp) ;
            if (*tmp == '\0') {
                continue;
            }
            for ( ++tmp ; *tmp == ' ' ; ++tmp);
            if ('\0' != *tmp) {
                return tmp;
            }
        }
    }

    return NULL;
}

static int opal_timer_linux_find_freq(void)
{
    FILE *fp;
    char *loc;
    float cpu_f;
    int ret;
    char buf[1024];

    fp = fopen("/proc/cpuinfo", "r");
    if (NULL == fp) {
        return OPAL_ERR_IN_ERRNO;
    }

    opal_timer_linux_freq = 0;

    if (0 == opal_timer_linux_freq) {
        /* first, look for a timebase field.  probably only on PPC,
           but one never knows */
        loc = find_info(fp, "timebase", buf, 1024);
        if (NULL != loc) {
            int freq;
            ret = sscanf(loc, "%d", &freq);
            if (1 == ret) {
                opal_timer_linux_freq = freq;
            }
        }
    }

    if (0 == opal_timer_linux_freq) {
        /* find the CPU speed - most timers are 1:1 with CPU speed */
        loc = find_info(fp, "cpu MHz", buf, 1024);
        if (NULL != loc) {
            ret = sscanf(loc, "%f", &cpu_f);
            if (1 == ret) {
                /* numer is in MHz - convert to Hz and make an integer */
                opal_timer_linux_freq = (opal_timer_t) cpu_f * 1000000;
            }
        }
    }

    if (0 == opal_timer_linux_freq) {
        /* look for the sparc way of getting cpu frequency */
        loc = find_info(fp, "Cpu0ClkTck", buf, 1024);
        if (NULL != loc) {
            unsigned int freq;
            ret = sscanf(loc, "%x", &freq);
            if (1 == ret) {
                opal_timer_linux_freq = freq;
            }
        }
    }

    fclose(fp);

    return OPAL_SUCCESS;
}

int opal_timer_linux_open(void)
{
    int ret = OPAL_SUCCESS;

    if(mca_timer_base_monotonic) {
#if OPAL_HAVE_CLOCK_GETTIME
        struct timespec res;
        if( 0 == clock_getres(CLOCK_MONOTONIC, &res)) {
            opal_timer_linux_freq = 1.e9;
            opal_timer_base_get_cycles = opal_timer_base_get_cycles_clock_gettime;
            opal_timer_base_get_usec = opal_timer_base_get_usec_clock_gettime;
            return ret;
        }
#else
#if (0 == OPAL_TIMER_MONOTONIC)
        /* Monotonic time requested but cannot be found. Complain! */
        opal_show_help("help-opal-timer-linux.txt", "monotonic not supported", 1);
#endif  /* (0 == OPAL_TIMER_MONOTONIC) */
#endif
    }
    ret = opal_timer_linux_find_freq();
    opal_timer_base_get_cycles = opal_timer_base_get_cycles_sys_timer;
    opal_timer_base_get_usec = opal_timer_base_get_usec_sys_timer;
    return ret;
}

#if OPAL_HAVE_CLOCK_GETTIME
opal_timer_t opal_timer_base_get_usec_clock_gettime(void)
{
    struct timespec tp;

    if( 0 == clock_gettime(CLOCK_MONOTONIC, &tp) ) {
        return (tp.tv_sec * 1e6 + tp.tv_nsec/1000);
    }
    return 0;
}

opal_timer_t opal_timer_base_get_cycles_clock_gettime(void)
{
    struct timespec tp;

    if( 0 == clock_gettime(CLOCK_MONOTONIC, &tp) ) {
        return (tp.tv_sec * 1e9 + tp.tv_nsec);
    }
    return 0;
}
#endif  /* OPAL_HAVE_CLOCK_GETTIME */

opal_timer_t opal_timer_base_get_cycles_sys_timer(void)
{
#if OPAL_HAVE_SYS_TIMER_GET_CYCLES
    return opal_sys_timer_get_cycles();
#else
    return 0;
#endif
}


opal_timer_t opal_timer_base_get_usec_sys_timer(void)
{
#if OPAL_HAVE_SYS_TIMER_GET_CYCLES
    /* freq is in Hz, so this gives usec */
    return opal_sys_timer_get_cycles() * 1000000  / opal_timer_linux_freq;
#else
    return 0;
#endif
}

opal_timer_t opal_timer_base_get_freq(void)
{
    return opal_timer_linux_freq;
}