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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hisi-rng.c (2809B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2016 HiSilicon Co., Ltd.
      4 */
      5
      6#include <linux/err.h>
      7#include <linux/kernel.h>
      8#include <linux/hw_random.h>
      9#include <linux/io.h>
     10#include <linux/module.h>
     11#include <linux/of.h>
     12#include <linux/platform_device.h>
     13#include <linux/random.h>
     14
     15#define RNG_SEED	0x0
     16#define RNG_CTRL	0x4
     17  #define RNG_SEED_SEL	BIT(2)
     18  #define RNG_RING_EN	BIT(1)
     19  #define RNG_EN	BIT(0)
     20#define RNG_RAN_NUM	0x10
     21#define RNG_PHY_SEED	0x14
     22
     23#define to_hisi_rng(p)	container_of(p, struct hisi_rng, rng)
     24
     25static int seed_sel;
     26module_param(seed_sel, int, S_IRUGO);
     27MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
     28
     29struct hisi_rng {
     30	void __iomem *base;
     31	struct hwrng rng;
     32};
     33
     34static int hisi_rng_init(struct hwrng *rng)
     35{
     36	struct hisi_rng *hrng = to_hisi_rng(rng);
     37	int val = RNG_EN;
     38	u32 seed;
     39
     40	/* get a random number as initial seed */
     41	get_random_bytes(&seed, sizeof(seed));
     42
     43	writel_relaxed(seed, hrng->base + RNG_SEED);
     44
     45	/**
     46	 * The seed is reload periodically, there are two choice
     47	 * of seeds, default seed using the value from LFSR, or
     48	 * will use seed generated by ring oscillator.
     49	 */
     50	if (seed_sel == 1)
     51		val |= RNG_RING_EN | RNG_SEED_SEL;
     52
     53	writel_relaxed(val, hrng->base + RNG_CTRL);
     54	return 0;
     55}
     56
     57static void hisi_rng_cleanup(struct hwrng *rng)
     58{
     59	struct hisi_rng *hrng = to_hisi_rng(rng);
     60
     61	writel_relaxed(0, hrng->base + RNG_CTRL);
     62}
     63
     64static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
     65{
     66	struct hisi_rng *hrng = to_hisi_rng(rng);
     67	u32 *data = buf;
     68
     69	*data = readl_relaxed(hrng->base + RNG_RAN_NUM);
     70	return 4;
     71}
     72
     73static int hisi_rng_probe(struct platform_device *pdev)
     74{
     75	struct hisi_rng *rng;
     76	int ret;
     77
     78	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
     79	if (!rng)
     80		return -ENOMEM;
     81
     82	platform_set_drvdata(pdev, rng);
     83
     84	rng->base = devm_platform_ioremap_resource(pdev, 0);
     85	if (IS_ERR(rng->base))
     86		return PTR_ERR(rng->base);
     87
     88	rng->rng.name = pdev->name;
     89	rng->rng.init = hisi_rng_init;
     90	rng->rng.cleanup = hisi_rng_cleanup;
     91	rng->rng.read = hisi_rng_read;
     92
     93	ret = devm_hwrng_register(&pdev->dev, &rng->rng);
     94	if (ret) {
     95		dev_err(&pdev->dev, "failed to register hwrng\n");
     96		return ret;
     97	}
     98
     99	return 0;
    100}
    101
    102static const struct of_device_id hisi_rng_dt_ids[] __maybe_unused = {
    103	{ .compatible = "hisilicon,hip04-rng" },
    104	{ .compatible = "hisilicon,hip05-rng" },
    105	{ }
    106};
    107MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
    108
    109static struct platform_driver hisi_rng_driver = {
    110	.probe		= hisi_rng_probe,
    111	.driver		= {
    112		.name	= "hisi-rng",
    113		.of_match_table = of_match_ptr(hisi_rng_dt_ids),
    114	},
    115};
    116
    117module_platform_driver(hisi_rng_driver);
    118
    119MODULE_LICENSE("GPL");
    120MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
    121MODULE_DESCRIPTION("Hisilicon random number generator driver");