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/timer.h> 25 #include <linux/irq.h> 26 27 #include <asm/thread_info.h> 28 #include <asm/sched_clock.h> 29 #include <asm/stacktrace.h> 30 #include <asm/mach/arch.h> 31 #include <asm/mach/time.h> 32 33 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \ 34 defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE) 35 /* this needs a better home */ 36 DEFINE_SPINLOCK(rtc_lock); 37 EXPORT_SYMBOL(rtc_lock); 38 #endif /* pc-style 'CMOS' RTC support */ 39 40 /* change this if you have some constant time drift */ 41 #define USECS_PER_JIFFY (1000000/HZ) 42 43 #ifdef CONFIG_SMP 44 unsigned long profile_pc(struct pt_regs *regs) 45 { 46 struct stackframe frame; 47 48 if (!in_lock_functions(regs->ARM_pc)) 49 return regs->ARM_pc; 50 51 frame.fp = regs->ARM_fp; 52 frame.sp = regs->ARM_sp; 53 frame.lr = regs->ARM_lr; 54 frame.pc = regs->ARM_pc; 55 do { 56 int ret = unwind_frame(&frame); 57 if (ret < 0) 58 return 0; 59 } while (in_lock_functions(frame.pc)); 60 61 return frame.pc; 62 } 63 EXPORT_SYMBOL(profile_pc); 64 #endif 65 66 #ifndef CONFIG_GENERIC_CLOCKEVENTS 67 /* 68 * Kernel system timer support. 69 */ 70 void timer_tick(void) 71 { 72 profile_tick(CPU_PROFILING); 73 xtime_update(1); 74 #ifndef CONFIG_SMP 75 update_process_times(user_mode(get_irq_regs())); 76 #endif 77 } 78 #endif 79 80 static void dummy_clock_access(struct timespec *ts) 81 { 82 ts->tv_sec = 0; 83 ts->tv_nsec = 0; 84 } 85 86 static clock_access_fn __read_persistent_clock = dummy_clock_access; 87 static clock_access_fn __read_boot_clock = dummy_clock_access;; 88 89 void read_persistent_clock(struct timespec *ts) 90 { 91 __read_persistent_clock(ts); 92 } 93 94 void read_boot_clock(struct timespec *ts) 95 { 96 __read_boot_clock(ts); 97 } 98 99 int __init register_persistent_clock(clock_access_fn read_boot, 100 clock_access_fn read_persistent) 101 { 102 /* Only allow the clockaccess functions to be registered once */ 103 if (__read_persistent_clock == dummy_clock_access && 104 __read_boot_clock == dummy_clock_access) { 105 if (read_boot) 106 __read_boot_clock = read_boot; 107 if (read_persistent) 108 __read_persistent_clock = read_persistent; 109 110 return 0; 111 } 112 113 return -EINVAL; 114 } 115 116 void __init time_init(void) 117 { 118 machine_desc->init_time(); 119 sched_clock_postinit(); 120 } 121