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/timer64.h>
  24
  25 static u32 sched_clock_multiplier;
  26 #define SCHED_CLOCK_SHIFT 16
  27
  28 static cycle_t tsc_read(struct clocksource *cs)
  29 {
  30         return get_cycles();
  31 }
  32
  33 static struct clocksource clocksource_tsc = {
  34         .name           = "timestamp",
  35         .rating         = 300,
  36         .read           = tsc_read,
  37         .mask           = CLOCKSOURCE_MASK(64),
  38         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  39 };
  40
  41 /*
  42  * scheduler clock - returns current time in nanoseconds.
  43  */
  44 u64 sched_clock(void)
  45 {
  46         u64 tsc = get_cycles();
  47
  48         return (tsc * sched_clock_multiplier) >> SCHED_CLOCK_SHIFT;
  49 }
  50
  51 void time_init(void)
  52 {
  53         u64 tmp = (u64)NSEC_PER_SEC << SCHED_CLOCK_SHIFT;
  54
  55         do_div(tmp, c6x_core_freq);
  56         sched_clock_multiplier = tmp;
  57
  58         clocksource_register_hz(&clocksource_tsc, c6x_core_freq);
  59
  60         /* write anything into TSCL to enable counting */
  61         set_creg(TSCL, 0);
  62
  63         /* probe for timer64 event timer */
  64         timer64_init();
  65 }