1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/arch/arm/kernel/time.c 4 * 5 * Copyright (C) 1991, 1992, 1995 Linus Torvalds 6 * Modifications for ARM (C) 1994-2001 Russell King 7 * 8 * This file contains the ARM-specific time handling details: 9 * reading the RTC at bootup, etc... 10 */ 11 #include <linux/clk-provider.h> 12 #include <linux/clocksource.h> 13 #include <linux/errno.h> 14 #include <linux/export.h> 15 #include <linux/init.h> 16 #include <linux/interrupt.h> 17 #include <linux/irq.h> 18 #include <linux/kernel.h> 19 #include <linux/profile.h> 20 #include <linux/sched.h> 21 #include <linux/sched_clock.h> 22 #include <linux/smp.h> 23 #include <linux/time.h> 24 #include <linux/timex.h> 25 #include <linux/timer.h> 26 27 #include <asm/mach/arch.h> 28 #include <asm/mach/time.h> 29 #include <asm/stacktrace.h> 30 #include <asm/thread_info.h> 31 32 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \ 33 defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE) 34 /* this needs a better home */ 35 DEFINE_SPINLOCK(rtc_lock); 36 EXPORT_SYMBOL(rtc_lock); 37 #endif /* pc-style 'CMOS' RTC support */ 38 39 /* change this if you have some constant time drift */ 40 #define USECS_PER_JIFFY (1000000/HZ) 41 42 #ifdef CONFIG_SMP 43 unsigned long profile_pc(struct pt_regs *regs) 44 { 45 struct stackframe frame; 46 47 if (!in_lock_functions(regs->ARM_pc)) 48 return regs->ARM_pc; 49 50 arm_get_current_stackframe(regs, &frame); 51 do { 52 int ret = unwind_frame(&frame); 53 if (ret < 0) 54 return 0; 55 } while (in_lock_functions(frame.pc)); 56 57 return frame.pc; 58 } 59 EXPORT_SYMBOL(profile_pc); 60 #endif 61 62 #ifndef CONFIG_GENERIC_CLOCKEVENTS 63 /* 64 * Kernel system timer support. 65 */ 66 void timer_tick(void) 67 { 68 profile_tick(CPU_PROFILING); 69 xtime_update(1); 70 #ifndef CONFIG_SMP 71 update_process_times(user_mode(get_irq_regs())); 72 #endif 73 } 74 #endif 75 76 static void dummy_clock_access(struct timespec64 *ts) 77 { 78 ts->tv_sec = 0; 79 ts->tv_nsec = 0; 80 } 81 82 static clock_access_fn __read_persistent_clock = dummy_clock_access; 83 84 void read_persistent_clock64(struct timespec64 *ts) 85 { 86 __read_persistent_clock(ts); 87 } 88 89 int __init register_persistent_clock(clock_access_fn read_persistent) 90 { 91 /* Only allow the clockaccess functions to be registered once */ 92 if (__read_persistent_clock == dummy_clock_access) { 93 if (read_persistent) 94 __read_persistent_clock = read_persistent; 95 return 0; 96 } 97 98 return -EINVAL; 99 } 100 101 void __init time_init(void) 102 { 103 if (machine_desc->init_time) { 104 machine_desc->init_time(); 105 } else { 106 #ifdef CONFIG_COMMON_CLK 107 of_clk_init(NULL); 108 #endif 109 timer_probe(); 110 } 111 } 112