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
 68struct meson_rng_data {
 69	void __iomem *base;
 70	struct platform_device *pdev;
 71	struct hwrng rng;
 72};
 73
 74static 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
 84static 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
109static const struct of_device_id meson_rng_of_match[] = {
110	{ .compatible = "amlogic,meson-rng", },
111	{},
112};
113MODULE_DEVICE_TABLE(of, meson_rng_of_match);
114
115static struct platform_driver meson_rng_driver = {
116	.probe	= meson_rng_probe,
117	.driver	= {
118		.name = "meson-rng",
119		.of_match_table = meson_rng_of_match,
120	},
121};
122
123module_platform_driver(meson_rng_driver);
124
125MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
126MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
127MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
128MODULE_LICENSE("Dual BSD/GPL");