/*      $NetBSD: cpufunc_asm.S,v 1.12 2003/09/06 09:14:52 rearnsha Exp $        */

/*-
 * Copyright (c) 1997,1998 Mark Brinicombe.
 * Copyright (c) 1997 Causality Limited
 * All rights reserved.
 *
 * 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 Causality Limited.
 * 4. The name of Causality Limited may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CAUSALITY LIMITED ``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 CAUSALITY LIMITED 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.
 *
 * RiscBSD kernel project
 *
 * cpufunc.S
 *
 * Assembly functions for CPU / MMU / TLB specific operations
 *
 * Created      : 30/01/97
 *
 */

#include <machine/asm.h>
#include <machine/sysreg.h>

        .text
        .align  2

ENTRY(cpufunc_nullop)
        RET
END(cpufunc_nullop)

/*
 * Generic functions to read/modify/write the internal coprocessor registers
 *
 *
 * Currently these registers are
 *  c1 - CPU Control
 *
 * All other registers are CPU architecture specific
 */

ENTRY(cpufunc_control)
        mrc     CP15_SCTLR(r3)          /* Read the control register */
        bic     r2, r3, r0              /* Clear bits */
        eor     r2, r2, r1              /* XOR bits */


        teq     r2, r3                  /* Only write if there is a change */
        mcrne   CP15_SCTLR(r2)          /* Write new control register */
        mov     r0, r3                  /* Return old value */

        RET
END(cpufunc_control)