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
|
/*
* drivers/char/hw_random/timeriomem-rng.c
*
* Copyright (C) 2009 Alexander Clouter <alex@digriz.org.uk>
*
* Derived from drivers/char/hw_random/omap-rng.c
* Copyright 2005 (c) MontaVista Software, Inc.
* Author: Deepak Saxena <dsaxena@plexity.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Overview:
* This driver is useful for platforms that have an IO range that provides
* periodic random data from a single IO memory address. All the platform
* has to do is provide the address and 'wait time' that new data becomes
* available.
*
* TODO: add support for reading sizes other than 32bits and masking
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/timeriomem-rng.h>
#include <linux/jiffies.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/completion.h>
static struct timeriomem_rng_data *timeriomem_rng_data;
static void timeriomem_rng_trigger(unsigned long);
static DEFINE_TIMER(timeriomem_rng_timer, timeriomem_rng_trigger, 0, 0);
/*
* have data return 1, however return 0 if we have nothing
*/
static int timeriomem_rng_data_present(struct hwrng *rng, int wait)
{
if (rng->priv == 0)
return 1;
if (!wait || timeriomem_rng_data->present)
return timeriomem_rng_data->present;
wait_for_completion(&timeriomem_rng_data->completion);
return 1;
}
static int timeriomem_rng_data_read(struct hwrng *rng, u32 *data)
{
unsigned long cur;
s32 delay;
*data = readl(timeriomem_rng_data->address);
if (rng->priv != 0) {
cur = jiffies;
delay = cur - timeriomem_rng_timer.expires;
delay = rng->priv - (delay % rng->priv);
timeriomem_rng_timer.expires = cur + delay;
timeriomem_rng_data->present = 0;
init_completion(&timeriomem_rng_data->completion);
add_timer(&timeriomem_rng_timer);
}
return 4;
}
static void timeriomem_rng_trigger(unsigned long dummy)
{
timeriomem_rng_data->present = 1;
complete(&timeriomem_rng_data->completion);
}
static struct hwrng timeriomem_rng_ops = {
.name = "timeriomem",
.data_present = timeriomem_rng_data_present,
.data_read = timeriomem_rng_data_read,
.priv = 0,
};
static int __init timeriomem_rng_probe(struct platform_device *pdev)
{
int ret;
timeriomem_rng_data = pdev->dev.platform_data;
if (timeriomem_rng_data->period != 0
&& usecs_to_jiffies(timeriomem_rng_data->period) > 0) {
timeriomem_rng_timer.expires = jiffies;
timeriomem_rng_ops.priv = usecs_to_jiffies(
timeriomem_rng_data->period);
}
timeriomem_rng_data->present = 1;
ret = hwrng_register(&timeriomem_rng_ops);
if (ret) {
dev_err(&pdev->dev, "problem registering\n");
return ret;
}
dev_info(&pdev->dev, "32bits from 0x%p @ %dus\n",
timeriomem_rng_data->address,
timeriomem_rng_data->period);
return 0;
}
static int __devexit timeriomem_rng_remove(struct platform_device *pdev)
{
del_timer_sync(&timeriomem_rng_timer);
hwrng_unregister(&timeriomem_rng_ops);
return 0;
}
static struct platform_driver timeriomem_rng_driver = {
.driver = {
.name = "timeriomem_rng",
.owner = THIS_MODULE,
},
.probe = timeriomem_rng_probe,
.remove = __devexit_p(timeriomem_rng_remove),
};
static int __init timeriomem_rng_init(void)
{
return platform_driver_register(&timeriomem_rng_driver);
}
static void __exit timeriomem_rng_exit(void)
{
platform_driver_unregister(&timeriomem_rng_driver);
}
module_init(timeriomem_rng_init);
module_exit(timeriomem_rng_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
MODULE_DESCRIPTION("Timer IOMEM H/W RNG driver");
|
