arch/mips/galileo-boards/ev96100/time.c

   1 /*
   2  * BRIEF MODULE DESCRIPTION
   3  *      Galileo EV96100 rtc routines.
   4  *
   5  * Copyright 2000 MontaVista Software Inc.
   6  * Author: MontaVista Software, Inc.
   7  *              ppopov@mvista.com or source@mvista.com
   8  *
   9  * This file was derived from Carsten Langgaard's
  10  * arch/mips/mips-boards/atlas/atlas_rtc.c.
  11  *
  12  * Carsten Langgaard, carstenl@mips.com
  13  * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
  14  *
  15  *  This program is free software; you can redistribute  it and/or modify it
  16  *  under  the terms of  the GNU General  Public License as published by the
  17  *  Free Software Foundation;  either version 2 of the  License, or (at your
  18  *  option) any later version.
  19  *
  20  *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
  21  *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
  22  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
  23  *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
  24  *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
  26  *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  27  *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
  28  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  29  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  *
  31  *  You should have received a copy of the  GNU General Public License along
  32  *  with this program; if not, write  to the Free Software Foundation, Inc.,
  33  *  675 Mass Ave, Cambridge, MA 02139, USA.
  34  */
  35 #include <linux/config.h>
  36 #include <linux/init.h>
  37 #include <linux/kernel_stat.h>
  38 #include <linux/module.h>
  39 #include <linux/sched.h>
  40 #include <linux/spinlock.h>
  41 #include <linux/timex.h>
  42
  43 #include <asm/mipsregs.h>
  44 #include <asm/ptrace.h>
  45 #include <asm/time.h>
  46
  47
  48 #define ALLINTS (IE_IRQ0 | IE_IRQ1 | IE_IRQ2 | IE_IRQ3 | IE_IRQ4 | IE_IRQ5)
  49
  50 extern volatile unsigned long wall_jiffies;
  51 unsigned long missed_heart_beats = 0;
  52
  53 static unsigned long r4k_offset; /* Amount to increment compare reg each time */
  54 static unsigned long r4k_cur;    /* What counter should be at next timer irq */
  55
  56 static inline void ack_r4ktimer(unsigned long newval)
  57 {
  58         write_c0_compare(newval);
  59 }
  60
  61 /*
  62  * There are a lot of conceptually broken versions of the MIPS timer interrupt
  63  * handler floating around.  This one is rather different, but the algorithm
  64  * is probably more robust.
  65  */
  66 void mips_timer_interrupt(struct pt_regs *regs)
  67 {
  68         int irq = 7; /* FIX ME */
  69
  70         if (r4k_offset == 0) {
  71             goto null;
  72         }
  73
  74         do {
  75                 kstat_this_cpu.irqs[irq]++;
  76                 do_timer(regs);
  77 #ifndef CONFIG_SMP
  78                 update_process_times(user_mode(regs));
  79 #endif
  80                 r4k_cur += r4k_offset;
  81                 ack_r4ktimer(r4k_cur);
  82
  83         } while (((unsigned long)read_c0_count()
  84                     - r4k_cur) < 0x7fffffff);
  85         return;
  86
  87 null:
  88         ack_r4ktimer(0);
  89 }