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	struct resource *res;
 46	int ret;
 47
 48	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 49	if (!data)
 50		return -ENOMEM;
 51
 52	data->pdev = pdev;
 53
 54	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 55	data->base = devm_ioremap_resource(dev, res);
 56	if (IS_ERR(data->base))
 57		return PTR_ERR(data->base);
 58
 59	data->core_clk = devm_clk_get(dev, "core");
 60	if (IS_ERR(data->core_clk))
 61		data->core_clk = NULL;
 62
 63	if (data->core_clk) {
 64		ret = clk_prepare_enable(data->core_clk);
 65		if (ret)
 66			return ret;
 67		ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
 68					       data->core_clk);
 69		if (ret)
 70			return ret;
 71	}
 72
 73	data->rng.name = pdev->name;
 74	data->rng.read = meson_rng_read;
 75
 76	platform_set_drvdata(pdev, data);
 77
 78	return devm_hwrng_register(dev, &data->rng);
 79}
 80
 81static const struct of_device_id meson_rng_of_match[] = {
 82	{ .compatible = "amlogic,meson-rng", },
 83	{},
 84};
 85MODULE_DEVICE_TABLE(of, meson_rng_of_match);
 86
 87static struct platform_driver meson_rng_driver = {
 88	.probe	= meson_rng_probe,
 89	.driver	= {
 90		.name = "meson-rng",
 91		.of_match_table = meson_rng_of_match,
 92	},
 93};
 94
 95module_platform_driver(meson_rng_driver);
 96
 97MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
 98MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
 99MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
100MODULE_LICENSE("Dual BSD/GPL");