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 #include <linux/clk.h>
66 
67 #define RNG_DATA 0x00
68 
69 struct meson_rng_data {
70 	void __iomem *base;
71 	struct platform_device *pdev;
72 	struct hwrng rng;
73 	struct clk *core_clk;
74 };
75 
76 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
77 {
78 	struct meson_rng_data *data =
79 			container_of(rng, struct meson_rng_data, rng);
80 
81 	*(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
82 
83 	return sizeof(u32);
84 }
85 
86 static void meson_rng_clk_disable(void *data)
87 {
88 	clk_disable_unprepare(data);
89 }
90 
91 static int meson_rng_probe(struct platform_device *pdev)
92 {
93 	struct device *dev = &pdev->dev;
94 	struct meson_rng_data *data;
95 	struct resource *res;
96 	int ret;
97 
98 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
99 	if (!data)
100 		return -ENOMEM;
101 
102 	data->pdev = pdev;
103 
104 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
105 	data->base = devm_ioremap_resource(dev, res);
106 	if (IS_ERR(data->base))
107 		return PTR_ERR(data->base);
108 
109 	data->core_clk = devm_clk_get(dev, "core");
110 	if (IS_ERR(data->core_clk))
111 		data->core_clk = NULL;
112 
113 	if (data->core_clk) {
114 		ret = clk_prepare_enable(data->core_clk);
115 		if (ret)
116 			return ret;
117 		ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
118 					       data->core_clk);
119 		if (ret)
120 			return ret;
121 	}
122 
123 	data->rng.name = pdev->name;
124 	data->rng.read = meson_rng_read;
125 
126 	platform_set_drvdata(pdev, data);
127 
128 	return devm_hwrng_register(dev, &data->rng);
129 }
130 
131 static const struct of_device_id meson_rng_of_match[] = {
132 	{ .compatible = "amlogic,meson-rng", },
133 	{},
134 };
135 MODULE_DEVICE_TABLE(of, meson_rng_of_match);
136 
137 static struct platform_driver meson_rng_driver = {
138 	.probe	= meson_rng_probe,
139 	.driver	= {
140 		.name = "meson-rng",
141 		.of_match_table = meson_rng_of_match,
142 	},
143 };
144 
145 module_platform_driver(meson_rng_driver);
146 
147 MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
148 MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
149 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
150 MODULE_LICENSE("Dual BSD/GPL");
151