mirror of https://gitee.com/openkylin/linux.git
59 lines
1.5 KiB
C
59 lines
1.5 KiB
C
/*
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* linux/arch/arm/kernel/arch_timer.c
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*
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* Copyright (C) 2011 ARM Ltd.
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <asm/delay.h>
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#include <asm/sched_clock.h>
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#include <clocksource/arm_arch_timer.h>
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static unsigned long arch_timer_read_counter_long(void)
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{
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return arch_timer_read_counter();
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}
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static u32 sched_clock_mult __read_mostly;
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static unsigned long long notrace arch_timer_sched_clock(void)
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{
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return arch_timer_read_counter() * sched_clock_mult;
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}
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static struct delay_timer arch_delay_timer;
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static void __init arch_timer_delay_timer_register(void)
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{
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/* Use the architected timer for the delay loop. */
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arch_delay_timer.read_current_timer = arch_timer_read_counter_long;
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arch_delay_timer.freq = arch_timer_get_rate();
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register_current_timer_delay(&arch_delay_timer);
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}
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int __init arch_timer_arch_init(void)
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{
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u32 arch_timer_rate = arch_timer_get_rate();
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if (arch_timer_rate == 0)
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return -ENXIO;
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arch_timer_delay_timer_register();
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/* Cache the sched_clock multiplier to save a divide in the hot path. */
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sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
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sched_clock_func = arch_timer_sched_clock;
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pr_info("sched_clock: ARM arch timer >56 bits at %ukHz, resolution %uns\n",
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arch_timer_rate / 1000, sched_clock_mult);
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return 0;
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}
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