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_optional(dev, "core");
58	if (IS_ERR(data->core_clk))
59		return dev_err_probe(dev, PTR_ERR(data->core_clk),
60				     "Failed to get core clock\n");
61
62	if (data->core_clk) {
63		ret = clk_prepare_enable(data->core_clk);
64		if (ret)
65			return ret;
66		ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
67					       data->core_clk);
68		if (ret)
69			return ret;
70	}
71
72	data->rng.name = pdev->name;
73	data->rng.read = meson_rng_read;
74
75	platform_set_drvdata(pdev, data);
76
77	return devm_hwrng_register(dev, &data->rng);
78}
79
80static const struct of_device_id meson_rng_of_match[] = {
81	{ .compatible = "amlogic,meson-rng", },
82	{},
83};
84MODULE_DEVICE_TABLE(of, meson_rng_of_match);
85
86static struct platform_driver meson_rng_driver = {
87	.probe	= meson_rng_probe,
88	.driver	= {
89		.name = "meson-rng",
90		.of_match_table = meson_rng_of_match,
91	},
92};
93
94module_platform_driver(meson_rng_driver);
95
96MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
97MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
98MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
99MODULE_LICENSE("Dual BSD/GPL");