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);
  55static void ccount_timer_set_mode(enum clock_event_mode mode,
  56                struct clock_event_device *evt);
  57struct ccount_timer {
  58        struct clock_event_device evt;
  59        int irq_enabled;
  60        char name[24];
  61};
  62static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
  63
  64static int ccount_timer_set_next_event(unsigned long delta,
  65                struct clock_event_device *dev)
  66{
  67        unsigned long flags, next;
  68        int ret = 0;
  69
  70        local_irq_save(flags);
  71        next = get_ccount() + delta;
  72        set_linux_timer(next);
  73        if (next - get_ccount() > delta)
  74                ret = -ETIME;
  75        local_irq_restore(flags);
  76
  77        return ret;
  78}
  79
  80static void ccount_timer_set_mode(enum clock_event_mode mode,
  81                struct clock_event_device *evt)
  82{
  83        struct ccount_timer *timer =
  84                container_of(evt, struct ccount_timer, evt);
  85
  86        /*
  87         * There is no way to disable the timer interrupt at the device level,
  88         * only at the intenable register itself. Since enable_irq/disable_irq
  89         * calls are nested, we need to make sure that these calls are
  90         * balanced.
  91         */
  92        switch (mode) {
  93        case CLOCK_EVT_MODE_SHUTDOWN:
  94        case CLOCK_EVT_MODE_UNUSED:
  95                if (timer->irq_enabled) {
  96                        disable_irq(evt->irq);
  97                        timer->irq_enabled = 0;
  98                }
  99                break;
 100        case CLOCK_EVT_MODE_RESUME:
 101        case CLOCK_EVT_MODE_ONESHOT:
 102                if (!timer->irq_enabled) {
 103                        enable_irq(evt->irq);
 104                        timer->irq_enabled = 1;
 105                }
 106        default:
 107                break;
 108        }
 109}
 110
 111static irqreturn_t timer_interrupt(int irq, void *dev_id);
 112static struct irqaction timer_irqaction = {
 113        .handler =      timer_interrupt,
 114        .flags =        IRQF_TIMER,
 115        .name =         "timer",
 116};
 117
 118void local_timer_setup(unsigned cpu)
 119{
 120        struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
 121        struct clock_event_device *clockevent = &timer->evt;
 122
 123        timer->irq_enabled = 1;
 124        clockevent->name = timer->name;
 125        snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
 126        clockevent->features = CLOCK_EVT_FEAT_ONESHOT;
 127        clockevent->rating = 300;
 128        clockevent->set_next_event = ccount_timer_set_next_event;
 129        clockevent->set_mode = ccount_timer_set_mode;
 130        clockevent->cpumask = cpumask_of(cpu);
 131        clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
 132        if (WARN(!clockevent->irq, "error: can't map timer irq"))
 133                return;
 134        clockevents_config_and_register(clockevent, ccount_freq,
 135                                        0xf, 0xffffffff);
 136}
 137
 138void __init time_init(void)
 139{
 140#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
 141        printk("Calibrating CPU frequency ");
 142        platform_calibrate_ccount();
 143        printk("%d.%02d MHz\n", (int)ccount_freq/1000000,
 144                        (int)(ccount_freq/10000)%100);
 145#else
 146        ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
 147#endif
 148        clocksource_register_hz(&ccount_clocksource, ccount_freq);
 149        local_timer_setup(0);
 150        setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction);
 151        sched_clock_register(ccount_sched_clock_read, 32, ccount_freq);
 152        clocksource_of_init();
 153}
 154
 155/*
 156 * The timer interrupt is called HZ times per second.
 157 */
 158
 159irqreturn_t timer_interrupt(int irq, void *dev_id)
 160{
 161        struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt;
 162
 163        set_linux_timer(get_linux_timer());
 164        evt->event_handler(evt);
 165
 166        /* Allow platform to do something useful (Wdog). */
 167        platform_heartbeat();
 168
 169        return IRQ_HANDLED;
 170}
 171
 172#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
 173void calibrate_delay(void)
 174{
 175        loops_per_jiffy = ccount_freq / HZ;
 176        printk("Calibrating delay loop (skipped)... "
 177               "%lu.%02lu BogoMIPS preset\n",
 178               loops_per_jiffy/(1000000/HZ),
 179               (loops_per_jiffy/(10000/HZ)) % 100);
 180}
 181#endif
 182