xref: /freebsd-10.0-release/sys/dev/random/nehemiah.c

/*-
 * Copyright (c) 2004 Mark R V Murray
 * 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
 *    in this position and unchanged.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
 *
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/sys/dev/random/nehemiah.c 128059 2004-04-09 15:47:10Z markm $");

#include <sys/types.h>
#include <sys/time.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/selinfo.h>

#include <dev/random/randomdev.h>

static int random_nehemiah_read(void *, int);

struct random_systat random_nehemiah = {
	.ident = "Hardware, VIA Nehemiah",
	.init = (random_init_func_t *)random_null_func,
	.deinit = (random_deinit_func_t *)random_null_func,
	.read = random_nehemiah_read,
	.write = (random_write_func_t *)random_null_func,
	.reseed = (random_reseed_func_t *)random_null_func,
	.seeded = 1,
};

/* ARGSUSED */
static int
random_nehemiah_read(void *buf, int c)
{
#if (defined(__GNUC__) || defined(__INTEL_COMPILER)) && defined(__i386__)
	int count = c;
	int rate = 0;

	/* VIA C3 Nehemiah "rep; xstore" */
	__asm __volatile("rep; .byte 0x0f, 0xa7, 0xc0"
				: "+D" (buf), "+c" (count), "=d" (rate)
				:
				: "memory");
#endif
	return (c);
}