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 <asm/thread_info.h> 29 #include <asm/sched_clock.h> 30 #include <asm/stacktrace.h> 31 #include <asm/mach/arch.h> 32 #include <asm/mach/time.h> 33 34 /* 35 * Our system timer. 36 */ 37 static struct sys_timer *system_timer; 38 39 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \ 40 defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE) 41 /* this needs a better home */ 42 DEFINE_SPINLOCK(rtc_lock); 43 EXPORT_SYMBOL(rtc_lock); 44 #endif /* pc-style 'CMOS' RTC support */ 45 46 /* change this if you have some constant time drift */ 47 #define USECS_PER_JIFFY (1000000/HZ) 48 49 #ifdef CONFIG_SMP 50 unsigned long profile_pc(struct pt_regs *regs) 51 { 52 struct stackframe frame; 53 54 if (!in_lock_functions(regs->ARM_pc)) 55 return regs->ARM_pc; 56 57 frame.fp = regs->ARM_fp; 58 frame.sp = regs->ARM_sp; 59 frame.lr = regs->ARM_lr; 60 frame.pc = regs->ARM_pc; 61 do { 62 int ret = unwind_frame(&frame); 63 if (ret < 0) 64 return 0; 65 } while (in_lock_functions(frame.pc)); 66 67 return frame.pc; 68 } 69 EXPORT_SYMBOL(profile_pc); 70 #endif 71 72 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET 73 u32 arch_gettimeoffset(void) 74 { 75 if (system_timer->offset != NULL) 76 return system_timer->offset() * 1000; 77 78 return 0; 79 } 80 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */ 81 82 #ifndef CONFIG_GENERIC_CLOCKEVENTS 83 /* 84 * Kernel system timer support. 85 */ 86 void timer_tick(void) 87 { 88 profile_tick(CPU_PROFILING); 89 xtime_update(1); 90 #ifndef CONFIG_SMP 91 update_process_times(user_mode(get_irq_regs())); 92 #endif 93 } 94 #endif 95 96 static void dummy_clock_access(struct timespec *ts) 97 { 98 ts->tv_sec = 0; 99 ts->tv_nsec = 0; 100 } 101 102 static clock_access_fn __read_persistent_clock = dummy_clock_access; 103 static clock_access_fn __read_boot_clock = dummy_clock_access;; 104 105 void read_persistent_clock(struct timespec *ts) 106 { 107 __read_persistent_clock(ts); 108 } 109 110 void read_boot_clock(struct timespec *ts) 111 { 112 __read_boot_clock(ts); 113 } 114 115 int __init register_persistent_clock(clock_access_fn read_boot, 116 clock_access_fn read_persistent) 117 { 118 /* Only allow the clockaccess functions to be registered once */ 119 if (__read_persistent_clock == dummy_clock_access && 120 __read_boot_clock == dummy_clock_access) { 121 if (read_boot) 122 __read_boot_clock = read_boot; 123 if (read_persistent) 124 __read_persistent_clock = read_persistent; 125 126 return 0; 127 } 128 129 return -EINVAL; 130 } 131 132 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS) 133 static int timer_suspend(void) 134 { 135 if (system_timer->suspend) 136 system_timer->suspend(); 137 138 return 0; 139 } 140 141 static void timer_resume(void) 142 { 143 if (system_timer->resume) 144 system_timer->resume(); 145 } 146 #else 147 #define timer_suspend NULL 148 #define timer_resume NULL 149 #endif 150 151 static struct syscore_ops timer_syscore_ops = { 152 .suspend = timer_suspend, 153 .resume = timer_resume, 154 }; 155 156 static int __init timer_init_syscore_ops(void) 157 { 158 register_syscore_ops(&timer_syscore_ops); 159 160 return 0; 161 } 162 163 device_initcall(timer_init_syscore_ops); 164 165 void __init time_init(void) 166 { 167 system_timer = machine_desc->timer; 168 system_timer->init(); 169 sched_clock_postinit(); 170 } 171 172