hisi-rng.c

  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	rng->base = devm_platform_ioremap_resource(pdev, 0);
 83	if (IS_ERR(rng->base))
 84		return PTR_ERR(rng->base);
 85
 86	rng->rng.name = pdev->name;
 87	rng->rng.init = hisi_rng_init;
 88	rng->rng.cleanup = hisi_rng_cleanup;
 89	rng->rng.read = hisi_rng_read;
 90
 91	ret = devm_hwrng_register(&pdev->dev, &rng->rng);
 92	if (ret)
 93		return dev_err_probe(&pdev->dev, ret, "failed to register hwrng\n");
 94
 95	return 0;
 96}
 97
 98static const struct of_device_id hisi_rng_dt_ids[] __maybe_unused = {
 99	{ .compatible = "hisilicon,hip04-rng" },
100	{ .compatible = "hisilicon,hip05-rng" },
101	{ }
102};
103MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
104
105static struct platform_driver hisi_rng_driver = {
106	.probe		= hisi_rng_probe,
107	.driver		= {
108		.name	= "hisi-rng",
109		.of_match_table = of_match_ptr(hisi_rng_dt_ids),
110	},
111};
112
113module_platform_driver(hisi_rng_driver);
114
115MODULE_LICENSE("GPL");
116MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
117MODULE_DESCRIPTION("Hisilicon random number generator driver");