arch/arm64/kernel/time.c

   1 /*
   2  * Based on arch/arm/kernel/time.c
   3  *
   4  * Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  * Modifications for ARM (C) 1994-2001 Russell King
   6  * Copyright (C) 2012 ARM Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <linux/export.h>
  22 #include <linux/kernel.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/time.h>
  25 #include <linux/init.h>
  26 #include <linux/sched.h>
  27 #include <linux/smp.h>
  28 #include <linux/timex.h>
  29 #include <linux/errno.h>
  30 #include <linux/profile.h>
  31 #include <linux/syscore_ops.h>
  32 #include <linux/timer.h>
  33 #include <linux/irq.h>
  34 #include <linux/delay.h>
  35
  36 #include <clocksource/arm_arch_timer.h>
  37
  38 #include <asm/thread_info.h>
  39 #include <asm/stacktrace.h>
  40
  41 #ifdef CONFIG_SMP
  42 unsigned long profile_pc(struct pt_regs *regs)
  43 {
  44         struct stackframe frame;
  45
  46         if (!in_lock_functions(regs->pc))
  47                 return regs->pc;
  48
  49         frame.fp = regs->regs[29];
  50         frame.sp = regs->sp;
  51         frame.pc = regs->pc;
  52         do {
  53                 int ret = unwind_frame(&frame);
  54                 if (ret < 0)
  55                         return 0;
  56         } while (in_lock_functions(frame.pc));
  57
  58         return frame.pc;
  59 }
  60 EXPORT_SYMBOL(profile_pc);
  61 #endif
  62
  63 static u64 sched_clock_mult __read_mostly;
  64
  65 unsigned long long notrace sched_clock(void)
  66 {
  67         return arch_timer_read_counter() * sched_clock_mult;
  68 }
  69
  70 int read_current_timer(unsigned long *timer_value)
  71 {
  72         *timer_value = arch_timer_read_counter();
  73         return 0;
  74 }
  75
  76 void __init time_init(void)
  77 {
  78         u32 arch_timer_rate;
  79
  80         if (arch_timer_init())
  81                 panic("Unable to initialise architected timer.\n");
  82
  83         arch_timer_rate = arch_timer_get_rate();
  84
  85         /* Cache the sched_clock multiplier to save a divide in the hot path. */
  86         sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
  87
  88         /* Calibrate the delay loop directly */
  89         lpj_fine = arch_timer_rate / HZ;
  90 }