time.c

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/*
 *  Port on Texas Instruments TMS320C6x architecture
 *
 *  Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
 *  Author: Aurelien Jacquiot ([email protected])
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/clocksource.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/profile.h>

#include <asm/special_insns.h>
#include <asm/timer64.h>

static u32 sched_clock_multiplier;
#define SCHED_CLOCK_SHIFT 16

static cycle_t tsc_read(struct clocksource *cs)
{
    return get_cycles();
}

static struct clocksource clocksource_tsc = {
    .name       = "timestamp",
    .rating     = 300,
    .read       = tsc_read,
    .mask       = CLOCKSOURCE_MASK(64),
    .flags      = CLOCK_SOURCE_IS_CONTINUOUS,
};

/*
 * scheduler clock - returns current time in nanoseconds.
 */
u64 sched_clock(void)
{
    u64 tsc = get_cycles();

    return (tsc * sched_clock_multiplier) >> SCHED_CLOCK_SHIFT;
}

void time_init(void)
{
    u64 tmp = (u64)NSEC_PER_SEC << SCHED_CLOCK_SHIFT;

    do_div(tmp, c6x_core_freq);
    sched_clock_multiplier = tmp;

    clocksource_register_hz(&clocksource_tsc, c6x_core_freq);

    /* write anything into TSCL to enable counting */
    set_creg(TSCL, 0);

    /* probe for timer64 event timer */
    timer64_init();
}