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

/*
 * BRIEF MODULE DESCRIPTION
 *	Galileo EV96100 rtc routines.
 *
 * Copyright 2000 MontaVista Software Inc.
 * Author: MontaVista Software, Inc.
 *         	ppopov@mvista.com or source@mvista.com
 *
 * This file was derived from Carsten Langgaard's
 * arch/mips/mips-boards/atlas/atlas_rtc.c.
 *
 * Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
 *
 *  This program is free software; you can redistribute  it and/or modify it
 *  under  the terms of  the GNU General  Public License as published by the
 *  Free Software Foundation;  either version 2 of the  License, or (at your
 *  option) any later version.
 *
 *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
 *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
 *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
 *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *  You should have received a copy of the  GNU General Public License along
 *  with this program; if not, write  to the Free Software Foundation, Inc.,
 *  675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/timex.h>

#include <asm/mipsregs.h>
#include <asm/ptrace.h>
#include <asm/time.h>


#define ALLINTS (IE_IRQ0 | IE_IRQ1 | IE_IRQ2 | IE_IRQ3 | IE_IRQ4 | IE_IRQ5)

extern volatile unsigned long wall_jiffies;
unsigned long missed_heart_beats = 0;

static unsigned long r4k_offset; /* Amount to increment compare reg each time */
static unsigned long r4k_cur;    /* What counter should be at next timer irq */

static inline void ack_r4ktimer(unsigned long newval)
{
	write_c0_compare(newval);
}

/*
 * There are a lot of conceptually broken versions of the MIPS timer interrupt
 * handler floating around.  This one is rather different, but the algorithm
 * is probably more robust.
 */
void mips_timer_interrupt(struct pt_regs *regs)
{
        int irq = 7; /* FIX ME */

	if (r4k_offset == 0) {
            goto null;
        }

	do {
		kstat_this_cpu.irqs[irq]++;
		do_timer(regs);
#ifndef CONFIG_SMP
		update_process_times(user_mode(regs));
#endif
		r4k_cur += r4k_offset;
		ack_r4ktimer(r4k_cur);

	} while (((unsigned long)read_c0_count()
                    - r4k_cur) < 0x7fffffff);
	return;

null:
	ack_r4ktimer(0);
}