kernel/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 EXPORT_SYMBOL(ccount_freq);
  34
  35 static cycle_t ccount_read(struct clocksource *cs)
  36 {
  37         return (cycle_t)get_ccount();
  38 }
  39
  40 static u64 notrace ccount_sched_clock_read(void)
  41 {
  42         return get_ccount();
  43 }
  44
  45 static 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
  53 static int ccount_timer_set_next_event(unsigned long delta,
  54                 struct clock_event_device *dev);
  55 static void ccount_timer_set_mode(enum clock_event_mode mode,
  56                 struct clock_event_device *evt);
  57 struct ccount_timer {
  58         struct clock_event_device evt;
  59         int irq_enabled;
  60         char name[24];
  61 };
  62 static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
  63
  64 static 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
  80 static 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
 111 static irqreturn_t timer_interrupt(int irq, void *dev_id);
 112 static struct irqaction timer_irqaction = {
 113         .handler =      timer_interrupt,
 114         .flags =        IRQF_TIMER,
 115         .name =         "timer",
 116 };
 117
 118 void 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
 138 void __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
 159 irqreturn_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
 173 void 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