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1 | /** |
2 | * Copyright (c) 2010-2012 Broadcom. All rights reserved. | |
3 | * Copyright (c) 2013 Lubomir Rintel | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU General Public License ("GPL") | |
7 | * version 2, as published by the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/hw_random.h> | |
8c4196a2 LR |
11 | #include <linux/io.h> |
12 | #include <linux/kernel.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/of_address.h> | |
15 | #include <linux/of_platform.h> | |
16 | #include <linux/platform_device.h> | |
17 | #include <linux/printk.h> | |
18 | ||
19 | #define RNG_CTRL 0x0 | |
20 | #define RNG_STATUS 0x4 | |
21 | #define RNG_DATA 0x8 | |
22 | ||
23 | /* enable rng */ | |
24 | #define RNG_RBGEN 0x1 | |
25 | ||
26 | /* the initial numbers generated are "less random" so will be discarded */ | |
27 | #define RNG_WARMUP_COUNT 0x40000 | |
28 | ||
29 | static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, | |
30 | bool wait) | |
31 | { | |
32 | void __iomem *rng_base = (void __iomem *)rng->priv; | |
33 | ||
34 | while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) { | |
35 | if (!wait) | |
36 | return 0; | |
37 | cpu_relax(); | |
38 | } | |
39 | ||
40 | *(u32 *)buf = __raw_readl(rng_base + RNG_DATA); | |
41 | return sizeof(u32); | |
42 | } | |
43 | ||
44 | static struct hwrng bcm2835_rng_ops = { | |
45 | .name = "bcm2835", | |
46 | .read = bcm2835_rng_read, | |
47 | }; | |
48 | ||
49 | static int bcm2835_rng_probe(struct platform_device *pdev) | |
50 | { | |
51 | struct device *dev = &pdev->dev; | |
52 | struct device_node *np = dev->of_node; | |
53 | void __iomem *rng_base; | |
54 | int err; | |
55 | ||
56 | /* map peripheral */ | |
57 | rng_base = of_iomap(np, 0); | |
58 | if (!rng_base) { | |
59 | dev_err(dev, "failed to remap rng regs"); | |
60 | return -ENODEV; | |
61 | } | |
62 | bcm2835_rng_ops.priv = (unsigned long)rng_base; | |
63 | ||
eb4a5346 MP |
64 | /* set warm-up count & enable */ |
65 | __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS); | |
66 | __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL); | |
67 | ||
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68 | /* register driver */ |
69 | err = hwrng_register(&bcm2835_rng_ops); | |
70 | if (err) { | |
71 | dev_err(dev, "hwrng registration failed\n"); | |
72 | iounmap(rng_base); | |
eb4a5346 | 73 | } else |
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74 | dev_info(dev, "hwrng registered\n"); |
75 | ||
8c4196a2 LR |
76 | return err; |
77 | } | |
78 | ||
79 | static int bcm2835_rng_remove(struct platform_device *pdev) | |
80 | { | |
81 | void __iomem *rng_base = (void __iomem *)bcm2835_rng_ops.priv; | |
82 | ||
83 | /* disable rng hardware */ | |
84 | __raw_writel(0, rng_base + RNG_CTRL); | |
85 | ||
86 | /* unregister driver */ | |
87 | hwrng_unregister(&bcm2835_rng_ops); | |
88 | iounmap(rng_base); | |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | static const struct of_device_id bcm2835_rng_of_match[] = { | |
94 | { .compatible = "brcm,bcm2835-rng", }, | |
95 | {}, | |
96 | }; | |
97 | MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match); | |
98 | ||
99 | static struct platform_driver bcm2835_rng_driver = { | |
100 | .driver = { | |
101 | .name = "bcm2835-rng", | |
8c4196a2 LR |
102 | .of_match_table = bcm2835_rng_of_match, |
103 | }, | |
104 | .probe = bcm2835_rng_probe, | |
105 | .remove = bcm2835_rng_remove, | |
106 | }; | |
107 | module_platform_driver(bcm2835_rng_driver); | |
108 | ||
109 | MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); | |
110 | MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver"); | |
22e8099f | 111 | MODULE_LICENSE("GPL v2"); |