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677d3e2f PK |
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 | ||
24 | struct atmel_trng { | |
25 | struct clk *clk; | |
26 | void __iomem *base; | |
27 | struct hwrng rng; | |
28 | }; | |
29 | ||
30 | static 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? */ | |
c475c06f | 37 | if (readl(trng->base + TRNG_ISR) & 1) { |
677d3e2f | 38 | *data = readl(trng->base + TRNG_ODATA); |
121daad8 PK |
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); | |
677d3e2f PK |
46 | return 4; |
47 | } else | |
48 | return 0; | |
49 | } | |
50 | ||
51 | static int atmel_trng_probe(struct platform_device *pdev) | |
52 | { | |
53 | struct atmel_trng *trng; | |
54 | struct resource *res; | |
55 | int ret; | |
56 | ||
677d3e2f PK |
57 | trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL); |
58 | if (!trng) | |
59 | return -ENOMEM; | |
60 | ||
bfaff75b JH |
61 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
62 | trng->base = devm_ioremap_resource(&pdev->dev, res); | |
63 | if (IS_ERR(trng->base)) | |
64 | return PTR_ERR(trng->base); | |
677d3e2f PK |
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 | ||
86 | err_register: | |
87 | clk_disable(trng->clk); | |
88 | err_enable: | |
89 | clk_put(trng->clk); | |
90 | ||
91 | return ret; | |
92 | } | |
93 | ||
39af33fc | 94 | static int atmel_trng_remove(struct platform_device *pdev) |
677d3e2f PK |
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 | ||
677d3e2f PK |
104 | return 0; |
105 | } | |
106 | ||
107 | #ifdef CONFIG_PM | |
108 | static int atmel_trng_suspend(struct device *dev) | |
109 | { | |
110 | struct atmel_trng *trng = dev_get_drvdata(dev); | |
111 | ||
112 | clk_disable(trng->clk); | |
113 | ||
114 | return 0; | |
115 | } | |
116 | ||
117 | static int atmel_trng_resume(struct device *dev) | |
118 | { | |
119 | struct atmel_trng *trng = dev_get_drvdata(dev); | |
120 | ||
121 | return clk_enable(trng->clk); | |
122 | } | |
123 | ||
124 | static const struct dev_pm_ops atmel_trng_pm_ops = { | |
125 | .suspend = atmel_trng_suspend, | |
126 | .resume = atmel_trng_resume, | |
127 | }; | |
128 | #endif /* CONFIG_PM */ | |
129 | ||
130 | static struct platform_driver atmel_trng_driver = { | |
131 | .probe = atmel_trng_probe, | |
bcd2982a | 132 | .remove = atmel_trng_remove, |
677d3e2f PK |
133 | .driver = { |
134 | .name = "atmel-trng", | |
135 | .owner = THIS_MODULE, | |
136 | #ifdef CONFIG_PM | |
137 | .pm = &atmel_trng_pm_ops, | |
138 | #endif /* CONFIG_PM */ | |
139 | }, | |
140 | }; | |
141 | ||
b21cb324 | 142 | module_platform_driver(atmel_trng_driver); |
677d3e2f PK |
143 | |
144 | MODULE_LICENSE("GPL"); | |
145 | MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>"); | |
146 | MODULE_DESCRIPTION("Atmel true random number generator driver"); |