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
|
/*
* Copyright (c) 2010-2011 Picochip Ltd., Jamie Iles
*
* 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.
*
* All enquiries to support@picochip.com
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#define DATA_REG_OFFSET 0x0200
#define CSR_REG_OFFSET 0x0278
#define CSR_OUT_EMPTY_MASK (1 << 24)
#define CSR_FAULT_MASK (1 << 1)
#define TRNG_BLOCK_RESET_MASK (1 << 0)
#define TAI_REG_OFFSET 0x0380
/*
* The maximum amount of time in microseconds to spend waiting for data if the
* core wants us to wait. The TRNG should generate 32 bits every 320ns so a
* timeout of 20us seems reasonable. The TRNG does builtin tests of the data
* for randomness so we can't always assume there is data present.
*/
#define PICO_TRNG_TIMEOUT 20
static void __iomem *rng_base;
static struct clk *rng_clk;
struct device *rng_dev;
static inline u32 picoxcell_trng_read_csr(void)
{
return __raw_readl(rng_base + CSR_REG_OFFSET);
}
static inline bool picoxcell_trng_is_empty(void)
{
return picoxcell_trng_read_csr() & CSR_OUT_EMPTY_MASK;
}
/*
* Take the random number generator out of reset and make sure the interrupts
* are masked. We shouldn't need to get large amounts of random bytes so just
* poll the status register. The hardware generates 32 bits every 320ns so we
* shouldn't have to wait long enough to warrant waiting for an IRQ.
*/
static void picoxcell_trng_start(void)
{
__raw_writel(0, rng_base + TAI_REG_OFFSET);
__raw_writel(0, rng_base + CSR_REG_OFFSET);
}
static void picoxcell_trng_reset(void)
{
__raw_writel(TRNG_BLOCK_RESET_MASK, rng_base + CSR_REG_OFFSET);
__raw_writel(TRNG_BLOCK_RESET_MASK, rng_base + TAI_REG_OFFSET);
picoxcell_trng_start();
}
/*
* Get some random data from the random number generator. The hw_random core
* layer provides us with locking.
*/
static int picoxcell_trng_read(struct hwrng *rng, void *buf, size_t max,
bool wait)
{
int i;
/* Wait for some data to become available. */
for (i = 0; i < PICO_TRNG_TIMEOUT && picoxcell_trng_is_empty(); ++i) {
if (!wait)
return 0;
udelay(1);
}
if (picoxcell_trng_read_csr() & CSR_FAULT_MASK) {
dev_err(rng_dev, "fault detected, resetting TRNG\n");
picoxcell_trng_reset();
return -EIO;
}
if (i == PICO_TRNG_TIMEOUT)
return 0;
*(u32 *)buf = __raw_readl(rng_base + DATA_REG_OFFSET);
return sizeof(u32);
}
static struct hwrng picoxcell_trng = {
.name = "picoxcell",
.read = picoxcell_trng_read,
};
static int picoxcell_trng_probe(struct platform_device *pdev)
{
int ret;
struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!mem) {
dev_warn(&pdev->dev, "no memory resource\n");
return -ENOMEM;
}
if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
"picoxcell_trng")) {
dev_warn(&pdev->dev, "unable to request io mem\n");
return -EBUSY;
}
rng_base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
if (!rng_base) {
dev_warn(&pdev->dev, "unable to remap io mem\n");
return -ENOMEM;
}
rng_clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(rng_clk)) {
dev_warn(&pdev->dev, "no clk\n");
return PTR_ERR(rng_clk);
}
ret = clk_enable(rng_clk);
if (ret) {
dev_warn(&pdev->dev, "unable to enable clk\n");
goto err_enable;
}
picoxcell_trng_start();
ret = hwrng_register(&picoxcell_trng);
if (ret)
goto err_register;
rng_dev = &pdev->dev;
dev_info(&pdev->dev, "pixoxcell random number generator active\n");
return 0;
err_register:
clk_disable(rng_clk);
err_enable:
clk_put(rng_clk);
return ret;
}
static int picoxcell_trng_remove(struct platform_device *pdev)
{
hwrng_unregister(&picoxcell_trng);
clk_disable(rng_clk);
clk_put(rng_clk);
return 0;
}
#ifdef CONFIG_PM
static int picoxcell_trng_suspend(struct device *dev)
{
clk_disable(rng_clk);
return 0;
}
static int picoxcell_trng_resume(struct device *dev)
{
return clk_enable(rng_clk);
}
static const struct dev_pm_ops picoxcell_trng_pm_ops = {
.suspend = picoxcell_trng_suspend,
.resume = picoxcell_trng_resume,
};
#endif /* CONFIG_PM */
static struct platform_driver picoxcell_trng_driver = {
.probe = picoxcell_trng_probe,
.remove = picoxcell_trng_remove,
.driver = {
.name = "picoxcell-trng",
.owner = THIS_MODULE,
#ifdef CONFIG_PM
.pm = &picoxcell_trng_pm_ops,
#endif /* CONFIG_PM */
},
};
module_platform_driver(picoxcell_trng_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamie Iles");
MODULE_DESCRIPTION("Picochip picoXcell TRNG driver");
|
