1 /* 2 * Based on arch/arm/kernel/time.c 3 * 4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds 5 * Modifications for ARM (C) 1994-2001 Russell King 6 * Copyright (C) 2012 ARM Ltd. 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program. If not, see <http://www.gnu.org/licenses/>. 19 */ 20 21 #include <linux/export.h> 22 #include <linux/kernel.h> 23 #include <linux/interrupt.h> 24 #include <linux/time.h> 25 #include <linux/init.h> 26 #include <linux/sched.h> 27 #include <linux/smp.h> 28 #include <linux/timex.h> 29 #include <linux/errno.h> 30 #include <linux/profile.h> 31 #include <linux/syscore_ops.h> 32 #include <linux/timer.h> 33 #include <linux/irq.h> 34 #include <linux/delay.h> 35 #include <linux/clocksource.h> 36 37 #include <clocksource/arm_arch_timer.h> 38 39 #include <asm/thread_info.h> 40 #include <asm/stacktrace.h> 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->pc)) 48 return regs->pc; 49 50 frame.fp = regs->regs[29]; 51 frame.sp = regs->sp; 52 frame.pc = regs->pc; 53 do { 54 int ret = unwind_frame(&frame); 55 if (ret < 0) 56 return 0; 57 } while (in_lock_functions(frame.pc)); 58 59 return frame.pc; 60 } 61 EXPORT_SYMBOL(profile_pc); 62 #endif 63 64 static u64 sched_clock_mult __read_mostly; 65 66 unsigned long long notrace sched_clock(void) 67 { 68 return arch_timer_read_counter() * sched_clock_mult; 69 } 70 71 int read_current_timer(unsigned long *timer_value) 72 { 73 *timer_value = arch_timer_read_counter(); 74 return 0; 75 } 76 77 void __init time_init(void) 78 { 79 u32 arch_timer_rate; 80 81 clocksource_of_init(); 82 83 arch_timer_rate = arch_timer_get_rate(); 84 if (!arch_timer_rate) 85 panic("Unable to initialise architected timer.\n"); 86 87 /* Cache the sched_clock multiplier to save a divide in the hot path. */ 88 sched_clock_mult = NSEC_PER_SEC / arch_timer_rate; 89 90 /* Calibrate the delay loop directly */ 91 lpj_fine = arch_timer_rate / HZ; 92 } 93