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");
122