root/arch/c6x/kernel/time.c

DEFINITIONS

1. tsc_read
2. sched_clock
3. time_init

   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 
  23 static u32 sched_clock_multiplier;
  24 #define SCHED_CLOCK_SHIFT 16
  25 
  26 static u64 tsc_read(struct clocksource *cs)
  27 {
  28         return get_cycles();
  29 }
  30 
  31 static 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  */
  42 u64 sched_clock(void)
  43 {
  44         u64 tsc = get_cycles();
  45 
  46         return (tsc * sched_clock_multiplier) >> SCHED_CLOCK_SHIFT;
  47 }
  48 
  49 void __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 }