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
25 static int seed_sel;
26 module_param(seed_sel, int, S_IRUGO);
27 MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
28
29 struct hisi_rng {
30 void __iomem *base;
31 struct hwrng rng;
32 };
33
hisi_rng_init(struct hwrng * rng)34 static 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
hisi_rng_cleanup(struct hwrng * rng)57 static 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
hisi_rng_read(struct hwrng * rng,void * buf,size_t max,bool wait)64 static 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
hisi_rng_probe(struct platform_device * pdev)73 static 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 dev_err(&pdev->dev, "failed to register hwrng\n");
94 return ret;
95 }
96
97 return 0;
98 }
99
100 static const struct of_device_id hisi_rng_dt_ids[] __maybe_unused = {
101 { .compatible = "hisilicon,hip04-rng" },
102 { .compatible = "hisilicon,hip05-rng" },
103 { }
104 };
105 MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
106
107 static struct platform_driver hisi_rng_driver = {
108 .probe = hisi_rng_probe,
109 .driver = {
110 .name = "hisi-rng",
111 .of_match_table = of_match_ptr(hisi_rng_dt_ids),
112 },
113 };
114
115 module_platform_driver(hisi_rng_driver);
116
117 MODULE_LICENSE("GPL");
118 MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
119 MODULE_DESCRIPTION("Hisilicon random number generator driver");
120