1 /* 2 * arch/xtensa/kernel/time.c 3 * 4 * Timer and clock support. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 * 10 * Copyright (C) 2005 Tensilica Inc. 11 * 12 * Chris Zankel <chris@zankel.net> 13 */ 14 15 #include <linux/errno.h> 16 #include <linux/sched.h> 17 #include <linux/time.h> 18 #include <linux/clocksource.h> 19 #include <linux/interrupt.h> 20 #include <linux/module.h> 21 #include <linux/init.h> 22 #include <linux/irq.h> 23 #include <linux/profile.h> 24 #include <linux/delay.h> 25 26 #include <asm/timex.h> 27 #include <asm/platform.h> 28 29 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 30 unsigned long ccount_per_jiffy; /* per 1/HZ */ 31 unsigned long nsec_per_ccount; /* nsec per ccount increment */ 32 #endif 33 34 static cycle_t ccount_read(void) 35 { 36 return (cycle_t)get_ccount(); 37 } 38 39 static struct clocksource ccount_clocksource = { 40 .name = "ccount", 41 .rating = 200, 42 .read = ccount_read, 43 .mask = CLOCKSOURCE_MASK(32), 44 }; 45 46 static irqreturn_t timer_interrupt(int irq, void *dev_id); 47 static struct irqaction timer_irqaction = { 48 .handler = timer_interrupt, 49 .flags = IRQF_DISABLED, 50 .name = "timer", 51 }; 52 53 void __init time_init(void) 54 { 55 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 56 printk("Calibrating CPU frequency "); 57 platform_calibrate_ccount(); 58 printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ), 59 (int)(ccount_per_jiffy/(10000/HZ))%100); 60 #endif 61 clocksource_register_hz(&ccount_clocksource, CCOUNT_PER_JIFFY * HZ); 62 63 /* Initialize the linux timer interrupt. */ 64 65 setup_irq(LINUX_TIMER_INT, &timer_irqaction); 66 set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY); 67 } 68 69 /* 70 * The timer interrupt is called HZ times per second. 71 */ 72 73 irqreturn_t timer_interrupt (int irq, void *dev_id) 74 { 75 76 unsigned long next; 77 78 next = get_linux_timer(); 79 80 again: 81 while ((signed long)(get_ccount() - next) > 0) { 82 83 profile_tick(CPU_PROFILING); 84 #ifndef CONFIG_SMP 85 update_process_times(user_mode(get_irq_regs())); 86 #endif 87 88 xtime_update(1); /* Linux handler in kernel/time/timekeeping */ 89 90 /* Note that writing CCOMPARE clears the interrupt. */ 91 92 next += CCOUNT_PER_JIFFY; 93 set_linux_timer(next); 94 } 95 96 /* Allow platform to do something useful (Wdog). */ 97 98 platform_heartbeat(); 99 100 /* Make sure we didn't miss any tick... */ 101 102 if ((signed long)(get_ccount() - next) > 0) 103 goto again; 104 105 return IRQ_HANDLED; 106 } 107 108 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 109 void __cpuinit calibrate_delay(void) 110 { 111 loops_per_jiffy = CCOUNT_PER_JIFFY; 112 printk("Calibrating delay loop (skipped)... " 113 "%lu.%02lu BogoMIPS preset\n", 114 loops_per_jiffy/(1000000/HZ), 115 (loops_per_jiffy/(10000/HZ)) % 100); 116 } 117 #endif 118