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