1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2013, Michael Ellerman, IBM Corporation.
*/
#define pr_fmt(fmt) "powernv-rng: " fmt
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <asm/archrandom.h>
#include <asm/cputable.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/smp.h>
#include "powernv.h"
#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
struct powernv_rng {
void __iomem *regs;
void __iomem *regs_real;
unsigned long mask;
};
static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
int powernv_hwrng_present(void)
{
struct powernv_rng *rng;
rng = get_cpu_var(powernv_rng);
put_cpu_var(rng);
return rng != NULL;
}
static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
{
unsigned long parity;
/* Calculate the parity of the value */
asm (".machine push; \
.machine power7; \
popcntd %0,%1; \
.machine pop;"
: "=r" (parity) : "r" (val));
/* xor our value with the previous mask */
val ^= rng->mask;
/* update the mask based on the parity of this value */
rng->mask = (rng->mask << 1) | (parity & 1);
return val;
}
int powernv_get_random_real_mode(unsigned long *v)
{
struct powernv_rng *rng;
rng = raw_cpu_read(powernv_rng);
if (!rng)
return 0;
*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
return 1;
}
static int powernv_get_random_darn(unsigned long *v)
{
unsigned long val;
/* Using DARN with L=1 - 64-bit conditioned random number */
asm volatile(PPC_DARN(%0, 1) : "=r"(val));
if (val == DARN_ERR)
return 0;
*v = val;
return 1;
}
static int initialise_darn(void)
{
unsigned long val;
int i;
if (!cpu_has_feature(CPU_FTR_ARCH_300))
return -ENODEV;
for (i = 0; i < 10; i++) {
if (powernv_get_random_darn(&val)) {
ppc_md.get_random_seed = powernv_get_random_darn;
return 0;
}
}
return -EIO;
}
int powernv_get_random_long(unsigned long *v)
{
struct powernv_rng *rng;
rng = get_cpu_var(powernv_rng);
*v = rng_whiten(rng, in_be64(rng->regs));
put_cpu_var(rng);
return 1;
}
EXPORT_SYMBOL_GPL(powernv_get_random_long);
static __init void rng_init_per_cpu(struct powernv_rng *rng,
struct device_node *dn)
{
int chip_id, cpu;
chip_id = of_get_ibm_chip_id(dn);
if (chip_id == -1)
pr_warn("No ibm,chip-id found for %pOF.\n", dn);
for_each_possible_cpu(cpu) {
if (per_cpu(powernv_rng, cpu) == NULL ||
cpu_to_chip_id(cpu) == chip_id) {
per_cpu(powernv_rng, cpu) = rng;
}
}
}
static __init int rng_create(struct device_node *dn)
{
struct powernv_rng *rng;
struct resource res;
unsigned long val;
rng = kzalloc(sizeof(*rng), GFP_KERNEL);
if (!rng)
return -ENOMEM;
if (of_address_to_resource(dn, 0, &res)) {
kfree(rng);
return -ENXIO;
}
rng->regs_real = (void __iomem *)res.start;
rng->regs = of_iomap(dn, 0);
if (!rng->regs) {
kfree(rng);
return -ENXIO;
}
val = in_be64(rng->regs);
rng->mask = val;
rng_init_per_cpu(rng, dn);
ppc_md.get_random_seed = powernv_get_random_long;
return 0;
}
static int __init pnv_get_random_long_early(unsigned long *v)
{
struct device_node *dn;
if (!slab_is_available())
return 0;
if (cmpxchg(&ppc_md.get_random_seed, pnv_get_random_long_early,
NULL) != pnv_get_random_long_early)
return 0;
for_each_compatible_node(dn, NULL, "ibm,power-rng")
rng_create(dn);
if (!ppc_md.get_random_seed)
return 0;
return ppc_md.get_random_seed(v);
}
void __init pnv_rng_init(void)
{
struct device_node *dn;
/* Prefer darn over the rest. */
if (!initialise_darn())
return;
dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
if (dn)
ppc_md.get_random_seed = pnv_get_random_long_early;
of_node_put(dn);
}
static int __init pnv_rng_late_init(void)
{
struct device_node *dn;
unsigned long v;
/* In case it wasn't called during init for some other reason. */
if (ppc_md.get_random_seed == pnv_get_random_long_early)
pnv_get_random_long_early(&v);
if (ppc_md.get_random_seed == powernv_get_random_long) {
for_each_compatible_node(dn, NULL, "ibm,power-rng")
of_platform_device_create(dn, NULL, NULL);
}
return 0;
}
machine_subsys_initcall(powernv, pnv_rng_late_init);
|
