2 * arch/xtensa/kernel/time.c
4 * Timer and clock support.
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
10 * Copyright (C) 2005 Tensilica Inc.
12 * Chris Zankel <chris@zankel.net>
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>
27 #include <asm/timex.h>
28 #include <asm/platform.h>
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 */
35 static cycle_t ccount_read(struct clocksource *cs)
37 return (cycle_t)get_ccount();
40 static struct clocksource ccount_clocksource = {
44 .mask = CLOCKSOURCE_MASK(32),
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,
54 void __init time_init(void)
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);
63 clocksource_register_hz(&ccount_clocksource, CCOUNT_PER_JIFFY * HZ);
65 /* Initialize the linux timer interrupt. */
67 irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
68 setup_irq(irq, &timer_irqaction);
69 set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
73 * The timer interrupt is called HZ times per second.
76 irqreturn_t timer_interrupt (int irq, void *dev_id)
81 next = get_linux_timer();
84 while ((signed long)(get_ccount() - next) > 0) {
86 profile_tick(CPU_PROFILING);
88 update_process_times(user_mode(get_irq_regs()));
91 xtime_update(1); /* Linux handler in kernel/time/timekeeping */
93 /* Note that writing CCOMPARE clears the interrupt. */
95 next += CCOUNT_PER_JIFFY;
96 set_linux_timer(next);
99 /* Allow platform to do something useful (Wdog). */
101 platform_heartbeat();
103 /* Make sure we didn't miss any tick... */
105 if ((signed long)(get_ccount() - next) > 0)
111 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
112 void __cpuinit calibrate_delay(void)
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);