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 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
  33 unsigned long ccount_freq;              /* ccount Hz */
  34 #endif
  35
  36 static cycle_t ccount_read(struct clocksource *cs)
  37 {
  38         return (cycle_t)get_ccount();
  39 }
  40
  41 static u32 notrace ccount_sched_clock_read(void)
  42 {
  43         return get_ccount();
  44 }
  45
  46 static struct clocksource ccount_clocksource = {
  47         .name = "ccount",
  48         .rating = 200,
  49         .read = ccount_read,
  50         .mask = CLOCKSOURCE_MASK(32),
  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 static struct ccount_timer_t {
  58         struct clock_event_device evt;
  59         int irq_enabled;
  60 } ccount_timer = {
  61         .evt = {
  62                 .name           = "ccount_clockevent",
  63                 .features       = CLOCK_EVT_FEAT_ONESHOT,
  64                 .rating         = 300,
  65                 .set_next_event = ccount_timer_set_next_event,
  66                 .set_mode       = ccount_timer_set_mode,
  67         },
  68 };
  69
  70 static int ccount_timer_set_next_event(unsigned long delta,
  71                 struct clock_event_device *dev)
  72 {
  73         unsigned long flags, next;
  74         int ret = 0;
  75
  76         local_irq_save(flags);
  77         next = get_ccount() + delta;
  78         set_linux_timer(next);
  79         if (next - get_ccount() > delta)
  80                 ret = -ETIME;
  81         local_irq_restore(flags);
  82
  83         return ret;
  84 }
  85
  86 static void ccount_timer_set_mode(enum clock_event_mode mode,
  87                 struct clock_event_device *evt)
  88 {
  89         struct ccount_timer_t *timer =
  90                 container_of(evt, struct ccount_timer_t, evt);
  91
  92         /*
  93          * There is no way to disable the timer interrupt at the device level,
  94          * only at the intenable register itself. Since enable_irq/disable_irq
  95          * calls are nested, we need to make sure that these calls are
  96          * balanced.
  97          */
  98         switch (mode) {
  99         case CLOCK_EVT_MODE_SHUTDOWN:
 100         case CLOCK_EVT_MODE_UNUSED:
 101                 if (timer->irq_enabled) {
 102                         disable_irq(evt->irq);
 103                         timer->irq_enabled = 0;
 104                 }
 105                 break;
 106         case CLOCK_EVT_MODE_RESUME:
 107         case CLOCK_EVT_MODE_ONESHOT:
 108                 if (!timer->irq_enabled) {
 109                         enable_irq(evt->irq);
 110                         timer->irq_enabled = 1;
 111                 }
 112         default:
 113                 break;
 114         }
 115 }
 116
 117 static irqreturn_t timer_interrupt(int irq, void *dev_id);
 118 static struct irqaction timer_irqaction = {
 119         .handler =      timer_interrupt,
 120         .flags =        IRQF_TIMER,
 121         .name =         "timer",
 122         .dev_id =       &ccount_timer,
 123 };
 124
 125 void __init time_init(void)
 126 {
 127 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
 128         printk("Calibrating CPU frequency ");
 129         platform_calibrate_ccount();
 130         printk("%d.%02d MHz\n", (int)ccount_freq/1000000,
 131                         (int)(ccount_freq/10000)%100);
 132 #endif
 133         clocksource_register_hz(&ccount_clocksource, CCOUNT_PER_JIFFY * HZ);
 134
 135         ccount_timer.evt.cpumask = cpumask_of(0);
 136         ccount_timer.evt.irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
 137         if (WARN(!ccount_timer.evt.irq, "error: can't map timer irq"))
 138                 return;
 139         clockevents_config_and_register(&ccount_timer.evt, ccount_freq, 0xf,
 140                         0xffffffff);
 141         setup_irq(ccount_timer.evt.irq, &timer_irqaction);
 142         ccount_timer.irq_enabled = 1;
 143
 144         setup_sched_clock(ccount_sched_clock_read, 32, ccount_freq);
 145 }
 146
 147 /*
 148  * The timer interrupt is called HZ times per second.
 149  */
 150
 151 irqreturn_t timer_interrupt (int irq, void *dev_id)
 152 {
 153         struct ccount_timer_t *timer = dev_id;
 154         struct clock_event_device *evt = &timer->evt;
 155
 156         evt->event_handler(evt);
 157
 158         /* Allow platform to do something useful (Wdog). */
 159         platform_heartbeat();
 160
 161         return IRQ_HANDLED;
 162 }
 163
 164 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
 165 void calibrate_delay(void)
 166 {
 167         loops_per_jiffy = CCOUNT_PER_JIFFY;
 168         printk("Calibrating delay loop (skipped)... "
 169                "%lu.%02lu BogoMIPS preset\n",
 170                loops_per_jiffy/(1000000/HZ),
 171                (loops_per_jiffy/(10000/HZ)) % 100);
 172 }
 173 #endif