xref: /src/sys/arch/hpcmips/vr/vr_idle.S

/*	$NetBSD: vr_idle.S,v 1.6.24.1 2002/12/18 05:00:58 gmcgarry Exp $	*/

/*
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Digital Equipment Corporation and Ralph Campbell.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 *
 * Copyright (C) 1989 Digital Equipment Corporation.
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby granted,
 * provided that the above copyright notice appears in all copies.
 * Digital Equipment Corporation makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 */

#include <mips/asm.h>
#include <mips/cpuregs.h>
#include <hpcmips/vr/vr_asm.h>

#include "opt_lockdebug.h"

#include "assym.h"

	.set	noreorder

/*
 * When no processes are on the runq, cpu_switch branches to idle
 * to wait for something to come ready.
 * Note: this is really a part of cpu_switch() but defined here for kernel
 * profiling.
 */
NESTED(vr_idle, CALLFRAME_SIZ, ra)
	.mask	0x80000000, -4
	subu	sp, sp, CALLFRAME_SIZ
	sw	ra, CALLFRAME_RA(sp)
	nop
1:
	lw	t0, _C_LABEL(sched_whichqs)	# look for non-empty queue
	bne	t0, zero, 2f
	nop
	.word	VR_OPCODE_STANDBY
	nop
	nop
	nop
	nop
	bne	t0, zero, 2f
	nop

	/* Try to zero some free pages. */
	lw	t0, _C_LABEL(uvm) + UVM_PAGE_IDLE_ZERO
	nop
	beq	t0, zero, 1b
	nop
	la	ra, 1b
	j	_C_LABEL(uvm_pageidlezero)
	nop
2:
	lw	ra, CALLFRAME_RA(sp)
	nop
	j	ra
	addu	sp, sp, CALLFRAME_SIZ
END(vr_idle)