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
|
/*
* RNG driver for TX4939 Random Number Generators (RNG)
*
* Copyright (C) 2009 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#define TX4939_RNG_RCSR 0x00000000
#define TX4939_RNG_ROR(n) (0x00000018 + (n) * 8)
#define TX4939_RNG_RCSR_INTE 0x00000008
#define TX4939_RNG_RCSR_RST 0x00000004
#define TX4939_RNG_RCSR_FIN 0x00000002
#define TX4939_RNG_RCSR_ST 0x00000001
struct tx4939_rng {
struct hwrng rng;
void __iomem *base;
u64 databuf[3];
unsigned int data_avail;
};
static void rng_io_start(void)
{
#ifndef CONFIG_64BIT
/*
* readq is reading a 64-bit register using a 64-bit load. On
* a 32-bit kernel however interrupts or any other processor
* exception would clobber the upper 32-bit of the processor
* register so interrupts need to be disabled.
*/
local_irq_disable();
#endif
}
static void rng_io_end(void)
{
#ifndef CONFIG_64BIT
local_irq_enable();
#endif
}
static u64 read_rng(void __iomem *base, unsigned int offset)
{
return ____raw_readq(base + offset);
}
static void write_rng(u64 val, void __iomem *base, unsigned int offset)
{
return ____raw_writeq(val, base + offset);
}
static int tx4939_rng_data_present(struct hwrng *rng, int wait)
{
struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
int i;
if (rngdev->data_avail)
return rngdev->data_avail;
for (i = 0; i < 20; i++) {
rng_io_start();
if (!(read_rng(rngdev->base, TX4939_RNG_RCSR)
& TX4939_RNG_RCSR_ST)) {
rngdev->databuf[0] =
read_rng(rngdev->base, TX4939_RNG_ROR(0));
rngdev->databuf[1] =
read_rng(rngdev->base, TX4939_RNG_ROR(1));
rngdev->databuf[2] =
read_rng(rngdev->base, TX4939_RNG_ROR(2));
rngdev->data_avail =
sizeof(rngdev->databuf) / sizeof(u32);
/* Start RNG */
write_rng(TX4939_RNG_RCSR_ST,
rngdev->base, TX4939_RNG_RCSR);
wait = 0;
}
rng_io_end();
if (!wait)
break;
/* 90 bus clock cycles by default for generation */
ndelay(90 * 5);
}
return rngdev->data_avail;
}
static int tx4939_rng_data_read(struct hwrng *rng, u32 *buffer)
{
struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
rngdev->data_avail--;
*buffer = *((u32 *)&rngdev->databuf + rngdev->data_avail);
return sizeof(u32);
}
static int __init tx4939_rng_probe(struct platform_device *dev)
{
struct tx4939_rng *rngdev;
struct resource *r;
int i;
r = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (!r)
return -EBUSY;
rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
if (!rngdev)
return -ENOMEM;
if (!devm_request_mem_region(&dev->dev, r->start, resource_size(r),
dev_name(&dev->dev)))
return -EBUSY;
rngdev->base = devm_ioremap(&dev->dev, r->start, resource_size(r));
if (!rngdev->base)
return -EBUSY;
rngdev->rng.name = dev_name(&dev->dev);
rngdev->rng.data_present = tx4939_rng_data_present;
rngdev->rng.data_read = tx4939_rng_data_read;
rng_io_start();
/* Reset RNG */
write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR);
write_rng(0, rngdev->base, TX4939_RNG_RCSR);
/* Start RNG */
write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR);
rng_io_end();
/*
* Drop first two results. From the datasheet:
* The quality of the random numbers generated immediately
* after reset can be insufficient. Therefore, do not use
* random numbers obtained from the first and second
* generations; use the ones from the third or subsequent
* generation.
*/
for (i = 0; i < 2; i++) {
rngdev->data_avail = 0;
if (!tx4939_rng_data_present(&rngdev->rng, 1))
return -EIO;
}
platform_set_drvdata(dev, rngdev);
return hwrng_register(&rngdev->rng);
}
static int __exit tx4939_rng_remove(struct platform_device *dev)
{
struct tx4939_rng *rngdev = platform_get_drvdata(dev);
hwrng_unregister(&rngdev->rng);
platform_set_drvdata(dev, NULL);
return 0;
}
static struct platform_driver tx4939_rng_driver = {
.driver = {
.name = "tx4939-rng",
.owner = THIS_MODULE,
},
.remove = tx4939_rng_remove,
};
static int __init tx4939rng_init(void)
{
return platform_driver_probe(&tx4939_rng_driver, tx4939_rng_probe);
}
static void __exit tx4939rng_exit(void)
{
platform_driver_unregister(&tx4939_rng_driver);
}
module_init(tx4939rng_init);
module_exit(tx4939rng_exit);
MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
MODULE_LICENSE("GPL");
|
