tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
3 *
4 * This file is licensed under the terms of the GNU General Public
5 * License version 2. This program is licensed "as is" without any
6 * warranty of any kind, whether express or implied.
7 */
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/slab.h>
12#include <linux/err.h>
13#include <linux/clk.h>
14#include <linux/io.h>
15#include <linux/hw_random.h>
16#include <linux/platform_device.h>
17
18#define TRNG_CR 0x00
19#define TRNG_ISR 0x1c
20#define TRNG_ODATA 0x50
21
22#define TRNG_KEY 0x524e4700 /* RNG */
23
24struct atmel_trng {
25 struct clk *clk;
26 void __iomem *base;
27 struct hwrng rng;
28};
29
30static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
31 bool wait)
32{
33 struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
34 u32 *data = buf;
35
36 /* data ready? */
37 if (readl(trng->base + TRNG_ODATA) & 1) {
38 *data = readl(trng->base + TRNG_ODATA);
39 return 4;
40 } else
41 return 0;
42}
43
44static int atmel_trng_probe(struct platform_device *pdev)
45{
46 struct atmel_trng *trng;
47 struct resource *res;
48 int ret;
49
50 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
51 if (!res)
52 return -EINVAL;
53
54 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
55 if (!trng)
56 return -ENOMEM;
57
58 if (!devm_request_mem_region(&pdev->dev, res->start,
59 resource_size(res), pdev->name))
60 return -EBUSY;
61
62 trng->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
63 if (!trng->base)
64 return -EBUSY;
65
66 trng->clk = clk_get(&pdev->dev, NULL);
67 if (IS_ERR(trng->clk))
68 return PTR_ERR(trng->clk);
69
70 ret = clk_enable(trng->clk);
71 if (ret)
72 goto err_enable;
73
74 writel(TRNG_KEY | 1, trng->base + TRNG_CR);
75 trng->rng.name = pdev->name;
76 trng->rng.read = atmel_trng_read;
77
78 ret = hwrng_register(&trng->rng);
79 if (ret)
80 goto err_register;
81
82 platform_set_drvdata(pdev, trng);
83
84 return 0;
85
86err_register:
87 clk_disable(trng->clk);
88err_enable:
89 clk_put(trng->clk);
90
91 return ret;
92}
93
94static int __devexit atmel_trng_remove(struct platform_device *pdev)
95{
96 struct atmel_trng *trng = platform_get_drvdata(pdev);
97
98 hwrng_unregister(&trng->rng);
99
100 writel(TRNG_KEY, trng->base + TRNG_CR);
101 clk_disable(trng->clk);
102 clk_put(trng->clk);
103
104 platform_set_drvdata(pdev, NULL);
105
106 return 0;
107}
108
109#ifdef CONFIG_PM
110static int atmel_trng_suspend(struct device *dev)
111{
112 struct atmel_trng *trng = dev_get_drvdata(dev);
113
114 clk_disable(trng->clk);
115
116 return 0;
117}
118
119static int atmel_trng_resume(struct device *dev)
120{
121 struct atmel_trng *trng = dev_get_drvdata(dev);
122
123 return clk_enable(trng->clk);
124}
125
126static const struct dev_pm_ops atmel_trng_pm_ops = {
127 .suspend = atmel_trng_suspend,
128 .resume = atmel_trng_resume,
129};
130#endif /* CONFIG_PM */
131
132static struct platform_driver atmel_trng_driver = {
133 .probe = atmel_trng_probe,
134 .remove = __devexit_p(atmel_trng_remove),
135 .driver = {
136 .name = "atmel-trng",
137 .owner = THIS_MODULE,
138#ifdef CONFIG_PM
139 .pm = &atmel_trng_pm_ops,
140#endif /* CONFIG_PM */
141 },
142};
143
144module_platform_driver(atmel_trng_driver);
145
146MODULE_LICENSE("GPL");
147MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
148MODULE_DESCRIPTION("Atmel true random number generator driver");