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
|
/*
* Nomadik RNG support
* Copyright 2009 Alessandro Rubini
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/amba/bus.h>
#include <linux/hw_random.h>
#include <linux/io.h>
static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
void __iomem *base = (void __iomem *)rng->priv;
/*
* The register is 32 bits and gives 16 random bits (low half).
* A subsequent read will delay the core for 400ns, so we just read
* once and accept the very unlikely very small delay, even if wait==0.
*/
*(u16 *)data = __raw_readl(base + 8) & 0xffff;
return 2;
}
/* we have at most one RNG per machine, granted */
static struct hwrng nmk_rng = {
.name = "nomadik",
.read = nmk_rng_read,
};
static int nmk_rng_probe(struct amba_device *dev, struct amba_id *id)
{
void __iomem *base;
int ret;
ret = amba_request_regions(dev, dev->dev.init_name);
if (ret)
return ret;
ret = -ENOMEM;
base = ioremap(dev->res.start, resource_size(&dev->res));
if (!base)
goto out_release;
nmk_rng.priv = (unsigned long)base;
ret = hwrng_register(&nmk_rng);
if (ret)
goto out_unmap;
return 0;
out_unmap:
iounmap(base);
out_release:
amba_release_regions(dev);
return ret;
}
static int nmk_rng_remove(struct amba_device *dev)
{
void __iomem *base = (void __iomem *)nmk_rng.priv;
hwrng_unregister(&nmk_rng);
iounmap(base);
amba_release_regions(dev);
return 0;
}
static struct amba_id nmk_rng_ids[] = {
{
.id = 0x000805e1,
.mask = 0x000fffff, /* top bits are rev and cfg: accept all */
},
{0, 0},
};
static struct amba_driver nmk_rng_driver = {
.drv = {
.owner = THIS_MODULE,
.name = "rng",
},
.probe = nmk_rng_probe,
.remove = nmk_rng_remove,
.id_table = nmk_rng_ids,
};
static int __init nmk_rng_init(void)
{
return amba_driver_register(&nmk_rng_driver);
}
static void __devexit nmk_rng_exit(void)
{
amba_driver_unregister(&nmk_rng_driver);
}
module_init(nmk_rng_init);
module_exit(nmk_rng_exit);
MODULE_LICENSE("GPL");
|
