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 platform_device *pdev;
22	struct hwrng rng;
23	struct clk *core_clk;
24};
25
26static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
27{
28	struct meson_rng_data *data =
29			container_of(rng, struct meson_rng_data, rng);
30
31	*(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
32
33	return sizeof(u32);
34}
35
36static void meson_rng_clk_disable(void *data)
37{
38	clk_disable_unprepare(data);
39}
40
41static int meson_rng_probe(struct platform_device *pdev)
42{
43	struct device *dev = &pdev->dev;
44	struct meson_rng_data *data;
45	int ret;
46
47	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
48	if (!data)
49		return -ENOMEM;
50
51	data->pdev = pdev;
52
53	data->base = devm_platform_ioremap_resource(pdev, 0);
54	if (IS_ERR(data->base))
55		return PTR_ERR(data->base);
56
57	data->core_clk = devm_clk_get(dev, "core");
58	if (IS_ERR(data->core_clk))
59		data->core_clk = NULL;
60
61	if (data->core_clk) {
62		ret = clk_prepare_enable(data->core_clk);
63		if (ret)
64			return ret;
65		ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
66					       data->core_clk);
67		if (ret)
68			return ret;
69	}
70
71	data->rng.name = pdev->name;
72	data->rng.read = meson_rng_read;
73
74	platform_set_drvdata(pdev, data);
75
76	return devm_hwrng_register(dev, &data->rng);
77}
78
79static const struct of_device_id meson_rng_of_match[] = {
80	{ .compatible = "amlogic,meson-rng", },
81	{},
82};
83MODULE_DEVICE_TABLE(of, meson_rng_of_match);
84
85static struct platform_driver meson_rng_driver = {
86	.probe	= meson_rng_probe,
87	.driver	= {
88		.name = "meson-rng",
89		.of_match_table = meson_rng_of_match,
90	},
91};
92
93module_platform_driver(meson_rng_driver);
94
95MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
96MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
97MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
98MODULE_LICENSE("Dual BSD/GPL");
99