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
  32 unsigned long ccount_freq;              /* ccount Hz */
  33
  34 static cycle_t ccount_read(struct clocksource *cs)
  35 {
  36         return (cycle_t)get_ccount();
  37 }
  38
  39 static u64 notrace ccount_sched_clock_read(void)
  40 {
  41         return get_ccount();
  42 }
  43
  44 static struct clocksource ccount_clocksource = {
  45         .name = "ccount",
  46         .rating = 200,
  47         .read = ccount_read,
  48         .mask = CLOCKSOURCE_MASK(32),
  49         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
  50 };
  51
  52 static int ccount_timer_set_next_event(unsigned long delta,
  53                 struct clock_event_device *dev);
  54 static void ccount_timer_set_mode(enum clock_event_mode mode,
  55                 struct clock_event_device *evt);
  56 struct ccount_timer {
  57         struct clock_event_device evt;
  58         int irq_enabled;
  59         char name[24];
  60 };
  61 static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
  62
  63 static int ccount_timer_set_next_event(unsigned long delta,
  64                 struct clock_event_device *dev)
  65 {
  66         unsigned long flags, next;
  67         int ret = 0;
  68
  69         local_irq_save(flags);
  70         next = get_ccount() + delta;
  71         set_linux_timer(next);
  72         if (next - get_ccount() > delta)
  73                 ret = -ETIME;
  74         local_irq_restore(flags);
  75
  76         return ret;
  77 }
  78
  79 static void ccount_timer_set_mode(enum clock_event_mode mode,
  80                 struct clock_event_device *evt)
  81 {
  82         struct ccount_timer *timer =
  83                 container_of(evt, struct ccount_timer, evt);
  84
  85         /*
  86          * There is no way to disable the timer interrupt at the device level,
  87          * only at the intenable register itself. Since enable_irq/disable_irq
  88          * calls are nested, we need to make sure that these calls are
  89          * balanced.
  90          */
  91         switch (mode) {
  92         case CLOCK_EVT_MODE_SHUTDOWN:
  93         case CLOCK_EVT_MODE_UNUSED:
  94                 if (timer->irq_enabled) {
  95                         disable_irq(evt->irq);
  96                         timer->irq_enabled = 0;
  97                 }
  98                 break;
  99         case CLOCK_EVT_MODE_RESUME:
 100         case CLOCK_EVT_MODE_ONESHOT:
 101                 if (!timer->irq_enabled) {
 102                         enable_irq(evt->irq);
 103                         timer->irq_enabled = 1;
 104                 }
 105         default:
 106                 break;
 107         }
 108 }
 109
 110 static irqreturn_t timer_interrupt(int irq, void *dev_id);
 111 static struct irqaction timer_irqaction = {
 112         .handler =      timer_interrupt,
 113         .flags =        IRQF_TIMER,
 114         .name =         "timer",
 115 };
 116
 117 void local_timer_setup(unsigned cpu)
 118 {
 119         struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
 120         struct clock_event_device *clockevent = &timer->evt;
 121
 122         timer->irq_enabled = 1;
 123         clockevent->name = timer->name;
 124         snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
 125         clockevent->features = CLOCK_EVT_FEAT_ONESHOT;
 126         clockevent->rating = 300;
 127         clockevent->set_next_event = ccount_timer_set_next_event;
 128         clockevent->set_mode = ccount_timer_set_mode;
 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
 137 void __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_of_init();
 152 }
 153
 154 /*
 155  * The timer interrupt is called HZ times per second.
 156  */
 157
 158 irqreturn_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
 172 void 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