target/linux/ubicom32/files/arch/ubicom32/kernel/timer_tick.c

   1 /*
   2  * arch/ubicom32/kernel/timer_tick.c
   3  *      Impelemets a perodic timer.
   4  *
   5  * (C) Copyright 2009, Ubicom, Inc.
   6  * Copyright (C) 1991, 1992, 1995  Linus Torvalds
   7  *
   8  * This file is part of the Ubicom32 Linux Kernel Port.
   9  *
  10  * The Ubicom32 Linux Kernel Port is free software: you can redistribute
  11  * it and/or modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation, either version 2 of the
  13  * License, or (at your option) any later version.
  14  *
  15  * The Ubicom32 Linux Kernel Port is distributed in the hope that it
  16  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  17  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  18  * the GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with the Ubicom32 Linux Kernel Port.  If not,
  22  * see <http://www.gnu.org/licenses/>.
  23  *
  24  * Ubicom32 implementation derived from (with many thanks):
  25  *   arch/m68knommu
  26  *   arch/blackfin
  27  *   arch/parisc
  28  */
  29
  30 #include <linux/profile.h>
  31
  32 #include <asm/ip5000.h>
  33 #include <asm/machdep.h>
  34 #if defined(CONFIG_SMP)
  35 #include <asm/smp.h>
  36 #endif
  37
  38 static unsigned int timervector;
  39 static unsigned int frequency;
  40
  41 /*
  42  * timer_tick()
  43  *      Kernel system timer support. Needs to keep up the real-time clock,
  44  *      as well as call the "do_timer()" routine every clocktick.
  45  */
  46 static irqreturn_t timer_tick(int irq, void *dummy)
  47 {
  48         int ticks;
  49
  50         BUG_ON(!irqs_disabled());
  51         ticks = timer_reset(timervector, frequency);
  52
  53         write_seqlock(&xtime_lock);
  54         do_timer(ticks);
  55         write_sequnlock(&xtime_lock);
  56
  57         update_process_times(user_mode(get_irq_regs()));
  58         profile_tick(CPU_PROFILING);
  59
  60 #if defined(CONFIG_SMP)
  61         smp_send_timer_all();
  62 #endif
  63         return(IRQ_HANDLED);
  64 }
  65
  66 /*
  67  * Data used by setup_irq for the timer.
  68  */
  69 static struct irqaction timer_irq = {
  70         .name    = "timer",
  71         .flags   = IRQF_DISABLED | IRQF_TIMER,
  72         .handler = timer_tick,
  73 };
  74
  75 /*
  76  * timer_tick_init()
  77  *      Implements a periodic timer
  78  *
  79  * This implementation directly calls the timer_tick() and move
  80  * the Linux kernel forward.  This is used when the user has not
  81  * selected GENERIC_CLOCKEVENTS.
  82  */
  83 void timer_tick_init(void)
  84 {
  85         /*
  86          * Now allocate a timer to ourselves.
  87          */
  88         timervector = timer_alloc();
  89         if (timervector == -1) {
  90                 printk(KERN_WARNING "where did the timer go?\n");
  91                 return;
  92         }
  93
  94         setup_irq(timervector, &timer_irq);
  95
  96         /*
  97          * Get the frequency from the processor device tree node or use
  98          * the default if not available. We will store this as the frequency
  99          * of the timer to avoid future calculations.
 100          */
 101         frequency = processor_frequency();
 102         if (frequency == 0) {
 103                 frequency = CLOCK_TICK_RATE;
 104         }
 105         frequency /= CONFIG_HZ;
 106
 107         printk(KERN_NOTICE "timer will interrupt every: %d cycles\n", frequency);
 108         timer_set(timervector, frequency);
 109 }