1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
2/*
3 * Copyright (c) 2016 BayLibre, SAS.
4 * Author: Neil Armstrong <narmstrong@baylibre.com>
5 * Copyright (C) 2014 Amlogic, Inc.
6 */
7#include <linux/err.h>
8#include <linux/module.h>
9#include <linux/io.h>
10#include <linux/platform_device.h>
11#include <linux/hw_random.h>
12#include <linux/slab.h>
13#include <linux/types.h>
14#include <linux/of.h>
15#include <linux/clk.h>
16
17#define RNG_DATA 0x00
18
19struct meson_rng_data {
20	void __iomem *base;
21	struct hwrng rng;
22};
23
24static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
25{
26	struct meson_rng_data *data =
27			container_of(rng, struct meson_rng_data, rng);
28
29	*(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
30
31	return sizeof(u32);
32}
33
34static int meson_rng_probe(struct platform_device *pdev)
35{
36	struct device *dev = &pdev->dev;
37	struct meson_rng_data *data;
38	struct clk *core_clk;
39
40	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
41	if (!data)
42		return -ENOMEM;
43
44	data->base = devm_platform_ioremap_resource(pdev, 0);
45	if (IS_ERR(data->base))
46		return PTR_ERR(data->base);
47
48	core_clk = devm_clk_get_optional_enabled(dev, "core");
49	if (IS_ERR(core_clk))
50		return dev_err_probe(dev, PTR_ERR(core_clk),
51				     "Failed to get core clock\n");
52
53	data->rng.name = pdev->name;
54	data->rng.read = meson_rng_read;
55
56	return devm_hwrng_register(dev, &data->rng);
57}
58
59static const struct of_device_id meson_rng_of_match[] = {
60	{ .compatible = "amlogic,meson-rng", },
61	{},
62};
63MODULE_DEVICE_TABLE(of, meson_rng_of_match);
64
65static struct platform_driver meson_rng_driver = {
66	.probe	= meson_rng_probe,
67	.driver	= {
68		.name = "meson-rng",
69		.of_match_table = meson_rng_of_match,
70	},
71};
72
73module_platform_driver(meson_rng_driver);
74
75MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
76MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
77MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
78MODULE_LICENSE("Dual BSD/GPL");
79