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
|
/*
* Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
* http://www.linux-sunxi.org
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* This driver exposes the Allwinner security ID, efuses exported in byte-
* sized chunks.
*/
#include <linux/compiler.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/sysfs.h>
#include <linux/types.h>
#define DRV_NAME "sunxi-sid"
struct sunxi_sid_data {
void __iomem *reg_base;
unsigned int keysize;
};
/* We read the entire key, due to a 32 bit read alignment requirement. Since we
* want to return the requested byte, this results in somewhat slower code and
* uses 4 times more reads as needed but keeps code simpler. Since the SID is
* only very rarely probed, this is not really an issue.
*/
static u8 sunxi_sid_read_byte(const struct sunxi_sid_data *sid_data,
const unsigned int offset)
{
u32 sid_key;
if (offset >= sid_data->keysize)
return 0;
sid_key = ioread32be(sid_data->reg_base + round_down(offset, 4));
sid_key >>= (offset % 4) * 8;
return sid_key; /* Only return the last byte */
}
static ssize_t sid_read(struct file *fd, struct kobject *kobj,
struct bin_attribute *attr, char *buf,
loff_t pos, size_t size)
{
struct platform_device *pdev;
struct sunxi_sid_data *sid_data;
int i;
pdev = to_platform_device(kobj_to_dev(kobj));
sid_data = platform_get_drvdata(pdev);
if (pos < 0 || pos >= sid_data->keysize)
return 0;
if (size > sid_data->keysize - pos)
size = sid_data->keysize - pos;
for (i = 0; i < size; i++)
buf[i] = sunxi_sid_read_byte(sid_data, pos + i);
return i;
}
static struct bin_attribute sid_bin_attr = {
.attr = { .name = "eeprom", .mode = S_IRUGO, },
.read = sid_read,
};
static int sunxi_sid_remove(struct platform_device *pdev)
{
device_remove_bin_file(&pdev->dev, &sid_bin_attr);
dev_dbg(&pdev->dev, "driver unloaded\n");
return 0;
}
static const struct of_device_id sunxi_sid_of_match[] = {
{ .compatible = "allwinner,sun4i-sid", .data = (void *)16},
{ .compatible = "allwinner,sun7i-a20-sid", .data = (void *)512},
{/* sentinel */},
};
MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
static int sunxi_sid_probe(struct platform_device *pdev)
{
struct sunxi_sid_data *sid_data;
struct resource *res;
const struct of_device_id *of_dev_id;
u8 *entropy;
unsigned int i;
sid_data = devm_kzalloc(&pdev->dev, sizeof(struct sunxi_sid_data),
GFP_KERNEL);
if (!sid_data)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
sid_data->reg_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(sid_data->reg_base))
return PTR_ERR(sid_data->reg_base);
of_dev_id = of_match_device(sunxi_sid_of_match, &pdev->dev);
if (!of_dev_id)
return -ENODEV;
sid_data->keysize = (int)of_dev_id->data;
platform_set_drvdata(pdev, sid_data);
sid_bin_attr.size = sid_data->keysize;
if (device_create_bin_file(&pdev->dev, &sid_bin_attr))
return -ENODEV;
entropy = kzalloc(sizeof(u8) * sid_data->keysize, GFP_KERNEL);
for (i = 0; i < sid_data->keysize; i++)
entropy[i] = sunxi_sid_read_byte(sid_data, i);
add_device_randomness(entropy, sid_data->keysize);
kfree(entropy);
dev_dbg(&pdev->dev, "loaded\n");
return 0;
}
static struct platform_driver sunxi_sid_driver = {
.probe = sunxi_sid_probe,
.remove = sunxi_sid_remove,
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
.of_match_table = sunxi_sid_of_match,
},
};
module_platform_driver(sunxi_sid_driver);
MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
MODULE_DESCRIPTION("Allwinner sunxi security id driver");
MODULE_LICENSE("GPL");
|
