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/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32#include <sys/param.h>
33#include <sys/kernel.h>
34#include <sys/conf.h>
35#include <sys/lock.h>
36#include <sys/malloc.h>
37#include <sys/module.h>
38#include <sys/random.h>
39#include <sys/systm.h>
40
41#include <machine/segments.h>
42#include <machine/pcb.h>
43#include <machine/md_var.h>
44#include <machine/specialreg.h>
45
46#include <dev/random/randomdev.h>
47
48static void random_nehemiah_init(void);
49static void random_nehemiah_deinit(void);
50static u_int random_nehemiah_read(void *, u_int);
51
52static struct random_source random_nehemiah = {
53	.rs_ident = "VIA Nehemiah Padlock RNG",
54	.rs_source = RANDOM_PURE_NEHEMIAH,
55	.rs_read = random_nehemiah_read
56};
57
58static struct fpu_kern_ctx *fpu_ctx_save;
59
60/* This H/W source never stores more than 8 bytes in one go */
61/* ARGSUSED */
62static __inline size_t
63VIA_RNG_store(void *buf)
64{
65	uint32_t retval = 0;
66	uint32_t rate = 0;
67
68#ifdef __GNUCLIKE_ASM
69	__asm __volatile(
70		"movl	$0,%%edx\n\t"
71		"xstore"
72			: "=a" (retval), "+d" (rate), "+D" (buf)
73			:
74			: "memory"
75	);
76#endif
77	if (rate == 0)
78		return (retval&0x1f);
79	return (0);
80}
81
82static void
83random_nehemiah_init(void)
84{
85
86	fpu_ctx_save = fpu_kern_alloc_ctx(FPU_KERN_NORMAL);
87}
88
89static void
90random_nehemiah_deinit(void)
91{
92
93	fpu_kern_free_ctx(fpu_ctx_save);
94}
95
96/* It is specifically allowed that buf is a multiple of sizeof(long) */
97static u_int
98random_nehemiah_read(void *buf, u_int c)
99{
100	uint8_t *b;
101	size_t count, ret;
102	uint64_t tmp;
103
104	fpu_kern_enter(curthread, fpu_ctx_save, FPU_KERN_NORMAL);
105	b = buf;
106	for (count = c; count > 0; count -= ret) {
107		ret = MIN(VIA_RNG_store(&tmp), count);
108		memcpy(b, &tmp, ret);
109		b += ret;
110	}
111	fpu_kern_leave(curthread, fpu_ctx_save);
112
113	return (c);
114}
115
116static int
117nehemiah_modevent(module_t mod, int type, void *unused)
118{
119	int error = 0;
120
121	switch (type) {
122	case MOD_LOAD:
123		if (via_feature_rng & VIA_HAS_RNG) {
124			random_source_register(&random_nehemiah);
125			printf("random: fast provider: \"%s\"\n", random_nehemiah.rs_ident);
126			random_nehemiah_init();
127		}
128		break;
129
130	case MOD_UNLOAD:
131		if (via_feature_rng & VIA_HAS_RNG) {
132			random_nehemiah_deinit();
133			random_source_deregister(&random_nehemiah);
134		}
135		break;
136
137	case MOD_SHUTDOWN:
138		break;
139
140	default:
141		error = EOPNOTSUPP;
142		break;
143
144	}
145
146	return (error);
147}
148
149DEV_MODULE(nehemiah, nehemiah_modevent, NULL);
150MODULE_VERSION(nehemiah, 1);
151MODULE_DEPEND(nehemiah, random_device, 1, 1, 1);
152