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

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  Port on Texas Instruments TMS320C6x architecture
   4 *
   5 *  Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
   6 *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
   7 */
   8
   9#include <linux/kernel.h>
  10#include <linux/clocksource.h>
  11#include <linux/errno.h>
  12#include <linux/sched.h>
  13#include <linux/param.h>
  14#include <linux/string.h>
  15#include <linux/mm.h>
  16#include <linux/interrupt.h>
  17#include <linux/timex.h>
  18#include <linux/profile.h>
  19
  20#include <asm/special_insns.h>
  21#include <asm/timer64.h>
  22
  23static u32 sched_clock_multiplier;
  24#define SCHED_CLOCK_SHIFT 16
  25
  26static u64 tsc_read(struct clocksource *cs)
  27{
  28        return get_cycles();
  29}
  30
  31static struct clocksource clocksource_tsc = {
  32        .name           = "timestamp",
  33        .rating         = 300,
  34        .read           = tsc_read,
  35        .mask           = CLOCKSOURCE_MASK(64),
  36        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  37};
  38
  39/*
  40 * scheduler clock - returns current time in nanoseconds.
  41 */
  42u64 sched_clock(void)
  43{
  44        u64 tsc = get_cycles();
  45
  46        return (tsc * sched_clock_multiplier) >> SCHED_CLOCK_SHIFT;
  47}
  48
  49void __init time_init(void)
  50{
  51        u64 tmp = (u64)NSEC_PER_SEC << SCHED_CLOCK_SHIFT;
  52
  53        do_div(tmp, c6x_core_freq);
  54        sched_clock_multiplier = tmp;
  55
  56        clocksource_register_hz(&clocksource_tsc, c6x_core_freq);
  57
  58        /* write anything into TSCL to enable counting */
  59        set_creg(TSCL, 0);
  60
  61        /* probe for timer64 event timer */
  62        timer64_init();
  63}
  64