cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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meson-rng.c (2343B)

      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");