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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ingenic-rng.c (3731B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Ingenic Random Number Generator driver
      4 * Copyright (c) 2017 PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
      5 * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
      6 */
      7
      8#include <linux/err.h>
      9#include <linux/kernel.h>
     10#include <linux/hw_random.h>
     11#include <linux/io.h>
     12#include <linux/iopoll.h>
     13#include <linux/module.h>
     14#include <linux/of_device.h>
     15#include <linux/platform_device.h>
     16#include <linux/slab.h>
     17
     18/* RNG register offsets */
     19#define RNG_REG_ERNG_OFFSET		0x0
     20#define RNG_REG_RNG_OFFSET		0x4
     21
     22/* bits within the ERND register */
     23#define ERNG_READY				BIT(31)
     24#define ERNG_ENABLE				BIT(0)
     25
     26enum ingenic_rng_version {
     27	ID_JZ4780,
     28	ID_X1000,
     29};
     30
     31/* Device associated memory */
     32struct ingenic_rng {
     33	enum ingenic_rng_version version;
     34
     35	void __iomem *base;
     36	struct hwrng rng;
     37};
     38
     39static int ingenic_rng_init(struct hwrng *rng)
     40{
     41	struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
     42
     43	writel(ERNG_ENABLE, priv->base + RNG_REG_ERNG_OFFSET);
     44
     45	return 0;
     46}
     47
     48static void ingenic_rng_cleanup(struct hwrng *rng)
     49{
     50	struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
     51
     52	writel(0, priv->base + RNG_REG_ERNG_OFFSET);
     53}
     54
     55static int ingenic_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
     56{
     57	struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
     58	u32 *data = buf;
     59	u32 status;
     60	int ret;
     61
     62	if (priv->version >= ID_X1000) {
     63		ret = readl_poll_timeout(priv->base + RNG_REG_ERNG_OFFSET, status,
     64					 status & ERNG_READY, 10, 1000);
     65		if (ret == -ETIMEDOUT) {
     66			pr_err("%s: Wait for RNG data ready timeout\n", __func__);
     67			return ret;
     68		}
     69	} else {
     70		/*
     71		 * A delay is required so that the current RNG data is not bit shifted
     72		 * version of previous RNG data which could happen if random data is
     73		 * read continuously from this device.
     74		 */
     75		udelay(20);
     76	}
     77
     78	*data = readl(priv->base + RNG_REG_RNG_OFFSET);
     79
     80	return 4;
     81}
     82
     83static int ingenic_rng_probe(struct platform_device *pdev)
     84{
     85	struct ingenic_rng *priv;
     86	int ret;
     87
     88	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
     89	if (!priv)
     90		return -ENOMEM;
     91
     92	priv->base = devm_platform_ioremap_resource(pdev, 0);
     93	if (IS_ERR(priv->base)) {
     94		pr_err("%s: Failed to map RNG registers\n", __func__);
     95		return PTR_ERR(priv->base);
     96	}
     97
     98	priv->version = (enum ingenic_rng_version)of_device_get_match_data(&pdev->dev);
     99
    100	priv->rng.name = pdev->name;
    101	priv->rng.init = ingenic_rng_init;
    102	priv->rng.cleanup = ingenic_rng_cleanup;
    103	priv->rng.read = ingenic_rng_read;
    104
    105	ret = hwrng_register(&priv->rng);
    106	if (ret) {
    107		dev_err(&pdev->dev, "Failed to register hwrng\n");
    108		return ret;
    109	}
    110
    111	platform_set_drvdata(pdev, priv);
    112
    113	dev_info(&pdev->dev, "Ingenic RNG driver registered\n");
    114	return 0;
    115}
    116
    117static int ingenic_rng_remove(struct platform_device *pdev)
    118{
    119	struct ingenic_rng *priv = platform_get_drvdata(pdev);
    120
    121	hwrng_unregister(&priv->rng);
    122
    123	writel(0, priv->base + RNG_REG_ERNG_OFFSET);
    124
    125	return 0;
    126}
    127
    128static const struct of_device_id ingenic_rng_of_match[] = {
    129	{ .compatible = "ingenic,jz4780-rng", .data = (void *) ID_JZ4780 },
    130	{ .compatible = "ingenic,x1000-rng", .data = (void *) ID_X1000 },
    131	{ /* sentinel */ }
    132};
    133MODULE_DEVICE_TABLE(of, ingenic_rng_of_match);
    134
    135static struct platform_driver ingenic_rng_driver = {
    136	.probe		= ingenic_rng_probe,
    137	.remove		= ingenic_rng_remove,
    138	.driver		= {
    139		.name	= "ingenic-rng",
    140		.of_match_table = ingenic_rng_of_match,
    141	},
    142};
    143
    144module_platform_driver(ingenic_rng_driver);
    145
    146MODULE_LICENSE("GPL");
    147MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>");
    148MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
    149MODULE_DESCRIPTION("Ingenic Random Number Generator driver");