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 | |
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(buf: &seed, len: 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 | |
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 | |
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 | |
73 | static int hisi_rng_probe(struct platform_device *pdev) |
74 | { |
75 | struct hisi_rng *rng; |
76 | int ret; |
77 | |
78 | rng = devm_kzalloc(dev: &pdev->dev, size: sizeof(*rng), GFP_KERNEL); |
79 | if (!rng) |
80 | return -ENOMEM; |
81 | |
82 | rng->base = devm_platform_ioremap_resource(pdev, index: 0); |
83 | if (IS_ERR(ptr: rng->base)) |
84 | return PTR_ERR(ptr: 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(dev: &pdev->dev, rng: &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 | |