1/*-
2 * Copyright (c) 2013-2015 Mark R V Murray
3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer
11 *    in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 */
28
29#include <sys/param.h>
30#include <sys/kernel.h>
31#include <sys/conf.h>
32#include <sys/lock.h>
33#include <sys/malloc.h>
34#include <sys/module.h>
35#include <sys/random.h>
36#include <sys/systm.h>
37
38#include <machine/segments.h>
39#include <machine/pcb.h>
40#include <machine/md_var.h>
41#include <machine/specialreg.h>
42
43#include <dev/random/randomdev.h>
44
45static u_int random_nehemiah_read(void *, u_int);
46
47static struct random_source random_nehemiah = {
48	.rs_ident = "VIA Nehemiah Padlock RNG",
49	.rs_source = RANDOM_PURE_NEHEMIAH,
50	.rs_read = random_nehemiah_read
51};
52
53/* This H/W source never stores more than 8 bytes in one go */
54/* ARGSUSED */
55static __inline size_t
56VIA_RNG_store(void *buf)
57{
58	uint32_t retval = 0;
59	uint32_t rate = 0;
60
61	__asm __volatile(
62		"movl	$0,%%edx\n\t"
63		".byte 0x0f, 0xa7, 0xc0"
64			: "=a" (retval), "+d" (rate), "+D" (buf)
65			:
66			: "memory"
67	);
68	if (rate == 0)
69		return (retval&0x1f);
70	return (0);
71}
72
73/* It is specifically allowed that buf is a multiple of sizeof(long) */
74static u_int
75random_nehemiah_read(void *buf, u_int c)
76{
77	uint8_t *b;
78	size_t count, ret;
79	uint64_t tmp;
80
81	fpu_kern_enter(curthread, NULL, FPU_KERN_NORMAL | FPU_KERN_NOCTX);
82	b = buf;
83	for (count = c; count > 0; count -= ret) {
84		ret = MIN(VIA_RNG_store(&tmp), count);
85		memcpy(b, &tmp, ret);
86		b += ret;
87	}
88	fpu_kern_leave(curthread, NULL);
89
90	return (c);
91}
92
93static int
94nehemiah_modevent(module_t mod, int type, void *unused)
95{
96	int error = 0;
97
98	switch (type) {
99	case MOD_LOAD:
100		if (via_feature_rng & VIA_HAS_RNG) {
101			random_source_register(&random_nehemiah);
102			printf("random: fast provider: \"%s\"\n", random_nehemiah.rs_ident);
103		}
104		break;
105
106	case MOD_UNLOAD:
107		if (via_feature_rng & VIA_HAS_RNG) {
108			random_source_deregister(&random_nehemiah);
109		}
110		break;
111
112	case MOD_SHUTDOWN:
113		break;
114
115	default:
116		error = EOPNOTSUPP;
117		break;
118
119	}
120
121	return (error);
122}
123
124static moduledata_t nehemiah_mod = {
125	"nehemiah",
126	nehemiah_modevent,
127	0
128};
129
130DECLARE_MODULE(nehemiah, nehemiah_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH);
131MODULE_VERSION(nehemiah, 1);
132MODULE_DEPEND(nehemiah, random_harvestq, 1, 1, 1);
133