1 /*
2  * This file is provided under a dual BSD/GPLv2 license.  When using or
3  * redistributing this file, you may do so under either license.
4  *
5  * GPL LICENSE SUMMARY
6  *
7  * Copyright (c) 2016 BayLibre, SAS.
8  * Author: Neil Armstrong <narmstrong@baylibre.com>
9  * Copyright (C) 2014 Amlogic, Inc.
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of version 2 of the GNU General Public License as
13  * published by the Free Software Foundation.
14  *
15  * This program is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, see <http://www.gnu.org/licenses/>.
22  * The full GNU General Public License is included in this distribution
23  * in the file called COPYING.
24  *
25  * BSD LICENSE
26  *
27  * Copyright (c) 2016 BayLibre, SAS.
28  * Author: Neil Armstrong <narmstrong@baylibre.com>
29  * Copyright (C) 2014 Amlogic, Inc.
30  *
31  * Redistribution and use in source and binary forms, with or without
32  * modification, are permitted provided that the following conditions
33  * are met:
34  *
35  *   * Redistributions of source code must retain the above copyright
36  *     notice, this list of conditions and the following disclaimer.
37  *   * Redistributions in binary form must reproduce the above copyright
38  *     notice, this list of conditions and the following disclaimer in
39  *     the documentation and/or other materials provided with the
40  *     distribution.
41  *   * Neither the name of Intel Corporation nor the names of its
42  *     contributors may be used to endorse or promote products derived
43  *     from this software without specific prior written permission.
44  *
45  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
46  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
47  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
48  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
49  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
50  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
51  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
52  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
53  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
54  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
55  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
56  */
57 #include <linux/err.h>
58 #include <linux/module.h>
59 #include <linux/io.h>
60 #include <linux/platform_device.h>
61 #include <linux/hw_random.h>
62 #include <linux/slab.h>
63 #include <linux/types.h>
64 #include <linux/of.h>
65 
66 #define RNG_DATA 0x00
67 
68 struct meson_rng_data {
69 	void __iomem *base;
70 	struct platform_device *pdev;
71 	struct hwrng rng;
72 };
73 
74 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
75 {
76 	struct meson_rng_data *data =
77 			container_of(rng, struct meson_rng_data, rng);
78 
79 	*(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
80 
81 	return sizeof(u32);
82 }
83 
84 static int meson_rng_probe(struct platform_device *pdev)
85 {
86 	struct device *dev = &pdev->dev;
87 	struct meson_rng_data *data;
88 	struct resource *res;
89 
90 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
91 	if (!data)
92 		return -ENOMEM;
93 
94 	data->pdev = pdev;
95 
96 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
97 	data->base = devm_ioremap_resource(dev, res);
98 	if (IS_ERR(data->base))
99 		return PTR_ERR(data->base);
100 
101 	data->rng.name = pdev->name;
102 	data->rng.read = meson_rng_read;
103 
104 	platform_set_drvdata(pdev, data);
105 
106 	return devm_hwrng_register(dev, &data->rng);
107 }
108 
109 static const struct of_device_id meson_rng_of_match[] = {
110 	{ .compatible = "amlogic,meson-rng", },
111 	{},
112 };
113 
114 static struct platform_driver meson_rng_driver = {
115 	.probe	= meson_rng_probe,
116 	.driver	= {
117 		.name = "meson-rng",
118 		.of_match_table = meson_rng_of_match,
119 	},
120 };
121 
122 module_platform_driver(meson_rng_driver);
123 
124 MODULE_ALIAS("platform:meson-rng");
125 MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
126 MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
127 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
128 MODULE_LICENSE("Dual BSD/GPL");
129