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_ISR) & 1) {
38 *data = readl(trng->base + TRNG_ODATA);
39 /*
40 ensure data ready is only set again AFTER the next data
41 word is ready in case it got set between checking ISR
42 and reading ODATA, so we don't risk re-reading the
43 same word
44 */
45 readl(trng->base + TRNG_ISR);
46 return 4;
47 } else
48 return 0;
49}
50
51static int atmel_trng_probe(struct platform_device *pdev)
52{
53 struct atmel_trng *trng;
54 struct resource *res;
55 int ret;
56
57 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
58 if (!res)
59 return -EINVAL;
60
61 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
62 if (!trng)
63 return -ENOMEM;
64
65 if (!devm_request_mem_region(&pdev->dev, res->start,
66 resource_size(res), pdev->name))
67 return -EBUSY;
68
69 trng->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
70 if (!trng->base)
71 return -EBUSY;
72
73 trng->clk = clk_get(&pdev->dev, NULL);
74 if (IS_ERR(trng->clk))
75 return PTR_ERR(trng->clk);
76
77 ret = clk_enable(trng->clk);
78 if (ret)
79 goto err_enable;
80
81 writel(TRNG_KEY | 1, trng->base + TRNG_CR);
82 trng->rng.name = pdev->name;
83 trng->rng.read = atmel_trng_read;
84
85 ret = hwrng_register(&trng->rng);
86 if (ret)
87 goto err_register;
88
89 platform_set_drvdata(pdev, trng);
90
91 return 0;
92
93err_register:
94 clk_disable(trng->clk);
95err_enable:
96 clk_put(trng->clk);
97
98 return ret;
99}
100
101static int atmel_trng_remove(struct platform_device *pdev)
102{
103 struct atmel_trng *trng = platform_get_drvdata(pdev);
104
105 hwrng_unregister(&trng->rng);
106
107 writel(TRNG_KEY, trng->base + TRNG_CR);
108 clk_disable(trng->clk);
109 clk_put(trng->clk);
110
111 return 0;
112}
113
114#ifdef CONFIG_PM
115static int atmel_trng_suspend(struct device *dev)
116{
117 struct atmel_trng *trng = dev_get_drvdata(dev);
118
119 clk_disable(trng->clk);
120
121 return 0;
122}
123
124static int atmel_trng_resume(struct device *dev)
125{
126 struct atmel_trng *trng = dev_get_drvdata(dev);
127
128 return clk_enable(trng->clk);
129}
130
131static const struct dev_pm_ops atmel_trng_pm_ops = {
132 .suspend = atmel_trng_suspend,
133 .resume = atmel_trng_resume,
134};
135#endif /* CONFIG_PM */
136
137static struct platform_driver atmel_trng_driver = {
138 .probe = atmel_trng_probe,
139 .remove = atmel_trng_remove,
140 .driver = {
141 .name = "atmel-trng",
142 .owner = THIS_MODULE,
143#ifdef CONFIG_PM
144 .pm = &atmel_trng_pm_ops,
145#endif /* CONFIG_PM */
146 },
147};
148
149module_platform_driver(atmel_trng_driver);
150
151MODULE_LICENSE("GPL");
152MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
153MODULE_DESCRIPTION("Atmel true random number generator driver");