LXR linux/arch/xtensa/kernel/time.c

   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/clockchips.h>
  20#include <linux/interrupt.h>
  21#include <linux/module.h>
  22#include <linux/init.h>
  23#include <linux/irq.h>
  24#include <linux/profile.h>
  25#include <linux/delay.h>
  26#include <linux/irqdomain.h>
  27#include <linux/sched_clock.h>
  28
  29#include <asm/timex.h>
  30#include <asm/platform.h>
  31
  32unsigned long ccount_freq;              /* ccount Hz */
  33EXPORT_SYMBOL(ccount_freq);
  34
  35static cycle_t ccount_read(struct clocksource *cs)
  36{
  37        return (cycle_t)get_ccount();
  38}
  39
  40static u64 notrace ccount_sched_clock_read(void)
  41{
  42        return get_ccount();
  43}
  44
  45static struct clocksource ccount_clocksource = {
  46        .name = "ccount",
  47        .rating = 200,
  48        .read = ccount_read,
  49        .mask = CLOCKSOURCE_MASK(32),
  50        .flags = CLOCK_SOURCE_IS_CONTINUOUS,
  51};
  52
  53static int ccount_timer_set_next_event(unsigned long delta,
  54                struct clock_event_device *dev);
  55struct ccount_timer {
  56        struct clock_event_device evt;
  57        int irq_enabled;
  58        char name[24];
  59};
  60static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
  61
  62static int ccount_timer_set_next_event(unsigned long delta,
  63                struct clock_event_device *dev)
  64{
  65        unsigned long flags, next;
  66        int ret = 0;
  67
  68        local_irq_save(flags);
  69        next = get_ccount() + delta;
  70        set_linux_timer(next);
  71        if (next - get_ccount() > delta)
  72                ret = -ETIME;
  73        local_irq_restore(flags);
  74
  75        return ret;
  76}
  77
  78/*
  79 * There is no way to disable the timer interrupt at the device level,
  80 * only at the intenable register itself. Since enable_irq/disable_irq
  81 * calls are nested, we need to make sure that these calls are
  82 * balanced.
  83 */
  84static int ccount_timer_shutdown(struct clock_event_device *evt)
  85{
  86        struct ccount_timer *timer =
  87                container_of(evt, struct ccount_timer, evt);
  88
  89        if (timer->irq_enabled) {
  90                disable_irq(evt->irq);
  91                timer->irq_enabled = 0;
  92        }
  93        return 0;
  94}
  95
  96static int ccount_timer_set_oneshot(struct clock_event_device *evt)
  97{
  98        struct ccount_timer *timer =
  99                container_of(evt, struct ccount_timer, evt);
 100
 101        if (!timer->irq_enabled) {
 102                enable_irq(evt->irq);
 103                timer->irq_enabled = 1;
 104        }
 105        return 0;
 106}
 107
 108static irqreturn_t timer_interrupt(int irq, void *dev_id);
 109static struct irqaction timer_irqaction = {
 110        .handler =      timer_interrupt,
 111        .flags =        IRQF_TIMER,
 112        .name =         "timer",
 113};
 114
 115void local_timer_setup(unsigned cpu)
 116{
 117        struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
 118        struct clock_event_device *clockevent = &timer->evt;
 119
 120        timer->irq_enabled = 1;
 121        clockevent->name = timer->name;
 122        snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
 123        clockevent->features = CLOCK_EVT_FEAT_ONESHOT;
 124        clockevent->rating = 300;
 125        clockevent->set_next_event = ccount_timer_set_next_event;
 126        clockevent->set_state_shutdown = ccount_timer_shutdown;
 127        clockevent->set_state_oneshot = ccount_timer_set_oneshot;
 128        clockevent->tick_resume = ccount_timer_set_oneshot;
 129        clockevent->cpumask = cpumask_of(cpu);
 130        clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
 131        if (WARN(!clockevent->irq, "error: can't map timer irq"))
 132                return;
 133        clockevents_config_and_register(clockevent, ccount_freq,
 134                                        0xf, 0xffffffff);
 135}
 136
 137void __init time_init(void)
 138{
 139#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
 140        printk("Calibrating CPU frequency ");
 141        platform_calibrate_ccount();
 142        printk("%d.%02d MHz\n", (int)ccount_freq/1000000,
 143                        (int)(ccount_freq/10000)%100);
 144#else
 145        ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
 146#endif
 147        clocksource_register_hz(&ccount_clocksource, ccount_freq);
 148        local_timer_setup(0);
 149        setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction);
 150        sched_clock_register(ccount_sched_clock_read, 32, ccount_freq);
 151        clocksource_probe();
 152}
 153
 154/*
 155 * The timer interrupt is called HZ times per second.
 156 */
 157
 158irqreturn_t timer_interrupt(int irq, void *dev_id)
 159{
 160        struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt;
 161
 162        set_linux_timer(get_linux_timer());
 163        evt->event_handler(evt);
 164
 165        /* Allow platform to do something useful (Wdog). */
 166        platform_heartbeat();
 167
 168        return IRQ_HANDLED;
 169}
 170
 171#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
 172void calibrate_delay(void)
 173{
 174        loops_per_jiffy = ccount_freq / HZ;
 175        printk("Calibrating delay loop (skipped)... "
 176               "%lu.%02lu BogoMIPS preset\n",
 177               loops_per_jiffy/(1000000/HZ),
 178               (loops_per_jiffy/(10000/HZ)) % 100);
 179}
 180#endif
 181