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 #include <linux/irqdomain.h> 26 27 #include <asm/timex.h> 28 #include <asm/platform.h> 29 30 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 31 unsigned long ccount_per_jiffy; /* per 1/HZ */ 32 unsigned long nsec_per_ccount; /* nsec per ccount increment */ 33 #endif 34 35 static cycle_t ccount_read(struct clocksource *cs) 36 { 37 return (cycle_t)get_ccount(); 38 } 39 40 static struct clocksource ccount_clocksource = { 41 .name = "ccount", 42 .rating = 200, 43 .read = ccount_read, 44 .mask = CLOCKSOURCE_MASK(32), 45 }; 46 47 static irqreturn_t timer_interrupt(int irq, void *dev_id); 48 static struct irqaction timer_irqaction = { 49 .handler = timer_interrupt, 50 .flags = IRQF_DISABLED, 51 .name = "timer", 52 }; 53 54 void __init time_init(void) 55 { 56 unsigned int irq; 57 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 58 printk("Calibrating CPU frequency "); 59 platform_calibrate_ccount(); 60 printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ), 61 (int)(ccount_per_jiffy/(10000/HZ))%100); 62 #endif 63 clocksource_register_hz(&ccount_clocksource, CCOUNT_PER_JIFFY * HZ); 64 65 /* Initialize the linux timer interrupt. */ 66 67 irq = irq_create_mapping(NULL, LINUX_TIMER_INT); 68 setup_irq(irq, &timer_irqaction); 69 set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY); 70 } 71 72 /* 73 * The timer interrupt is called HZ times per second. 74 */ 75 76 irqreturn_t timer_interrupt (int irq, void *dev_id) 77 { 78 79 unsigned long next; 80 81 next = get_linux_timer(); 82 83 again: 84 while ((signed long)(get_ccount() - next) > 0) { 85 86 profile_tick(CPU_PROFILING); 87 #ifndef CONFIG_SMP 88 update_process_times(user_mode(get_irq_regs())); 89 #endif 90 91 xtime_update(1); /* Linux handler in kernel/time/timekeeping */ 92 93 /* Note that writing CCOMPARE clears the interrupt. */ 94 95 next += CCOUNT_PER_JIFFY; 96 set_linux_timer(next); 97 } 98 99 /* Allow platform to do something useful (Wdog). */ 100 101 platform_heartbeat(); 102 103 /* Make sure we didn't miss any tick... */ 104 105 if ((signed long)(get_ccount() - next) > 0) 106 goto again; 107 108 return IRQ_HANDLED; 109 } 110 111 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 112 void __cpuinit calibrate_delay(void) 113 { 114 loops_per_jiffy = CCOUNT_PER_JIFFY; 115 printk("Calibrating delay loop (skipped)... " 116 "%lu.%02lu BogoMIPS preset\n", 117 loops_per_jiffy/(1000000/HZ), 118 (loops_per_jiffy/(10000/HZ)) % 100); 119 } 120 #endif 121