LXR linux/arch/c6x/kernel/time.c

   1/*
   2 *  Port on Texas Instruments TMS320C6x architecture
   3 *
   4 *  Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
   5 *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
   6 *
   7 *  This program is free software; you can redistribute it and/or modify
   8 *  it under the terms of the GNU General Public License version 2 as
   9 *  published by the Free Software Foundation.
  10 */
  11
  12#include <linux/kernel.h>
  13#include <linux/clocksource.h>
  14#include <linux/errno.h>
  15#include <linux/sched.h>
  16#include <linux/param.h>
  17#include <linux/string.h>
  18#include <linux/mm.h>
  19#include <linux/interrupt.h>
  20#include <linux/timex.h>
  21#include <linux/profile.h>
  22
  23#include <asm/special_insns.h>
  24#include <asm/timer64.h>
  25
  26static u32 sched_clock_multiplier;
  27#define SCHED_CLOCK_SHIFT 16
  28
  29static u64 tsc_read(struct clocksource *cs)
  30{
  31        return get_cycles();
  32}
  33
  34static struct clocksource clocksource_tsc = {
  35        .name           = "timestamp",
  36        .rating         = 300,
  37        .read           = tsc_read,
  38        .mask           = CLOCKSOURCE_MASK(64),
  39        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  40};
  41
  42/*
  43 * scheduler clock - returns current time in nanoseconds.
  44 */
  45u64 sched_clock(void)
  46{
  47        u64 tsc = get_cycles();
  48
  49        return (tsc * sched_clock_multiplier) >> SCHED_CLOCK_SHIFT;
  50}
  51
  52void __init time_init(void)
  53{
  54        u64 tmp = (u64)NSEC_PER_SEC << SCHED_CLOCK_SHIFT;
  55
  56        do_div(tmp, c6x_core_freq);
  57        sched_clock_multiplier = tmp;
  58
  59        clocksource_register_hz(&clocksource_tsc, c6x_core_freq);
  60
  61        /* write anything into TSCL to enable counting */
  62        set_creg(TSCL, 0);
  63
  64        /* probe for timer64 event timer */
  65        timer64_init();
  66}
  67