kernel-ark/arch/arm/plat-iop/cp6.c

/*
 * IOP Coprocessor-6 access handler
 * Copyright (c) 2006, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * 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., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 */
#include <linux/init.h>
#include <asm/traps.h>
#include <asm/ptrace.h>

static int cp6_trap(struct pt_regs *regs, unsigned int instr)
{
	u32 temp;

        /* enable cp6 access */
        asm volatile (
		"mrc	p15, 0, %0, c15, c1, 0\n\t"
		"orr	%0, %0, #(1 << 6)\n\t"
		"mcr	p15, 0, %0, c15, c1, 0\n\t"
		: "=r"(temp));

	return 0;
}

/* permit kernel space cp6 access
 * deny user space cp6 access
 */
static struct undef_hook cp6_hook = {
	.instr_mask     = 0x0f000ff0,
	.instr_val      = 0x0e000610,
	.cpsr_mask      = MODE_MASK,
	.cpsr_val       = SVC_MODE,
	.fn             = cp6_trap,
};

void __init iop_init_cp6_handler(void)
{
	register_undef_hook(&cp6_hook);
}