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/clk-provider.h> 15 #include <linux/clocksource.h> 16 #include <linux/errno.h> 17 #include <linux/export.h> 18 #include <linux/init.h> 19 #include <linux/interrupt.h> 20 #include <linux/irq.h> 21 #include <linux/kernel.h> 22 #include <linux/profile.h> 23 #include <linux/sched.h> 24 #include <linux/sched_clock.h> 25 #include <linux/smp.h> 26 #include <linux/time.h> 27 #include <linux/timex.h> 28 #include <linux/timer.h> 29 30 #include <asm/mach/arch.h> 31 #include <asm/mach/time.h> 32 #include <asm/stacktrace.h> 33 #include <asm/thread_info.h> 34 35 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \ 36 defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE) 37 /* this needs a better home */ 38 DEFINE_SPINLOCK(rtc_lock); 39 EXPORT_SYMBOL(rtc_lock); 40 #endif /* pc-style 'CMOS' RTC support */ 41 42 /* change this if you have some constant time drift */ 43 #define USECS_PER_JIFFY (1000000/HZ) 44 45 #ifdef CONFIG_SMP 46 unsigned long profile_pc(struct pt_regs *regs) 47 { 48 struct stackframe frame; 49 50 if (!in_lock_functions(regs->ARM_pc)) 51 return regs->ARM_pc; 52 53 arm_get_current_stackframe(regs, &frame); 54 do { 55 int ret = unwind_frame(&frame); 56 if (ret < 0) 57 return 0; 58 } while (in_lock_functions(frame.pc)); 59 60 return frame.pc; 61 } 62 EXPORT_SYMBOL(profile_pc); 63 #endif 64 65 #ifndef CONFIG_GENERIC_CLOCKEVENTS 66 /* 67 * Kernel system timer support. 68 */ 69 void timer_tick(void) 70 { 71 profile_tick(CPU_PROFILING); 72 xtime_update(1); 73 #ifndef CONFIG_SMP 74 update_process_times(user_mode(get_irq_regs())); 75 #endif 76 } 77 #endif 78 79 static void dummy_clock_access(struct timespec64 *ts) 80 { 81 ts->tv_sec = 0; 82 ts->tv_nsec = 0; 83 } 84 85 static clock_access_fn __read_persistent_clock = dummy_clock_access; 86 87 void read_persistent_clock64(struct timespec64 *ts) 88 { 89 __read_persistent_clock(ts); 90 } 91 92 int __init register_persistent_clock(clock_access_fn read_persistent) 93 { 94 /* Only allow the clockaccess functions to be registered once */ 95 if (__read_persistent_clock == dummy_clock_access) { 96 if (read_persistent) 97 __read_persistent_clock = read_persistent; 98 return 0; 99 } 100 101 return -EINVAL; 102 } 103 104 void __init time_init(void) 105 { 106 if (machine_desc->init_time) { 107 machine_desc->init_time(); 108 } else { 109 #ifdef CONFIG_COMMON_CLK 110 of_clk_init(NULL); 111 #endif 112 timer_probe(); 113 } 114 } 115