1 /* 2 * linux/arch/arm/kernel/time.c 3 * 4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds 5 * Modifications for ARM (C) 1994-2001 Russell King 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 * This file contains the ARM-specific time handling details: 12 * reading the RTC at bootup, etc... 13 */ 14 #include <linux/export.h> 15 #include <linux/kernel.h> 16 #include <linux/interrupt.h> 17 #include <linux/time.h> 18 #include <linux/init.h> 19 #include <linux/sched.h> 20 #include <linux/smp.h> 21 #include <linux/timex.h> 22 #include <linux/errno.h> 23 #include <linux/profile.h> 24 #include <linux/syscore_ops.h> 25 #include <linux/timer.h> 26 #include <linux/irq.h> 27 28 #include <linux/mc146818rtc.h> 29 30 #include <asm/leds.h> 31 #include <asm/thread_info.h> 32 #include <asm/sched_clock.h> 33 #include <asm/stacktrace.h> 34 #include <asm/mach/arch.h> 35 #include <asm/mach/time.h> 36 37 /* 38 * Our system timer. 39 */ 40 static struct sys_timer *system_timer; 41 42 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \ 43 defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE) 44 /* this needs a better home */ 45 DEFINE_SPINLOCK(rtc_lock); 46 EXPORT_SYMBOL(rtc_lock); 47 #endif /* pc-style 'CMOS' RTC support */ 48 49 /* change this if you have some constant time drift */ 50 #define USECS_PER_JIFFY (1000000/HZ) 51 52 #ifdef CONFIG_SMP 53 unsigned long profile_pc(struct pt_regs *regs) 54 { 55 struct stackframe frame; 56 57 if (!in_lock_functions(regs->ARM_pc)) 58 return regs->ARM_pc; 59 60 frame.fp = regs->ARM_fp; 61 frame.sp = regs->ARM_sp; 62 frame.lr = regs->ARM_lr; 63 frame.pc = regs->ARM_pc; 64 do { 65 int ret = unwind_frame(&frame); 66 if (ret < 0) 67 return 0; 68 } while (in_lock_functions(frame.pc)); 69 70 return frame.pc; 71 } 72 EXPORT_SYMBOL(profile_pc); 73 #endif 74 75 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET 76 u32 arch_gettimeoffset(void) 77 { 78 if (system_timer->offset != NULL) 79 return system_timer->offset() * 1000; 80 81 return 0; 82 } 83 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */ 84 85 #ifdef CONFIG_LEDS_TIMER 86 static inline void do_leds(void) 87 { 88 static unsigned int count = HZ/2; 89 90 if (--count == 0) { 91 count = HZ/2; 92 leds_event(led_timer); 93 } 94 } 95 #else 96 #define do_leds() 97 #endif 98 99 100 #ifndef CONFIG_GENERIC_CLOCKEVENTS 101 /* 102 * Kernel system timer support. 103 */ 104 void timer_tick(void) 105 { 106 profile_tick(CPU_PROFILING); 107 do_leds(); 108 xtime_update(1); 109 #ifndef CONFIG_SMP 110 update_process_times(user_mode(get_irq_regs())); 111 #endif 112 } 113 #endif 114 115 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS) 116 static int timer_suspend(void) 117 { 118 if (system_timer->suspend) 119 system_timer->suspend(); 120 121 return 0; 122 } 123 124 static void timer_resume(void) 125 { 126 if (system_timer->resume) 127 system_timer->resume(); 128 } 129 #else 130 #define timer_suspend NULL 131 #define timer_resume NULL 132 #endif 133 134 static struct syscore_ops timer_syscore_ops = { 135 .suspend = timer_suspend, 136 .resume = timer_resume, 137 }; 138 139 static int __init timer_init_syscore_ops(void) 140 { 141 register_syscore_ops(&timer_syscore_ops); 142 143 return 0; 144 } 145 146 device_initcall(timer_init_syscore_ops); 147 148 void __init time_init(void) 149 { 150 system_timer = machine_desc->timer; 151 system_timer->init(); 152 #ifdef CONFIG_HAVE_SCHED_CLOCK 153 sched_clock_postinit(); 154 #endif 155 } 156 157