1 /*
2 * Copyright (C) 2016 HiSilicon Co., Ltd.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9 #include <linux/err.h>
10 #include <linux/kernel.h>
11 #include <linux/hw_random.h>
12 #include <linux/io.h>
13 #include <linux/module.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/random.h>
17
18 #define RNG_SEED 0x0
19 #define RNG_CTRL 0x4
20 #define RNG_SEED_SEL BIT(2)
21 #define RNG_RING_EN BIT(1)
22 #define RNG_EN BIT(0)
23 #define RNG_RAN_NUM 0x10
24 #define RNG_PHY_SEED 0x14
25
26 #define to_hisi_rng(p) container_of(p, struct hisi_rng, rng)
27
28 static int seed_sel;
29 module_param(seed_sel, int, S_IRUGO);
30 MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
31
32 struct hisi_rng {
33 void __iomem *base;
34 struct hwrng rng;
35 };
36
hisi_rng_init(struct hwrng * rng)37 static int hisi_rng_init(struct hwrng *rng)
38 {
39 struct hisi_rng *hrng = to_hisi_rng(rng);
40 int val = RNG_EN;
41 u32 seed;
42
43 /* get a random number as initial seed */
44 get_random_bytes(&seed, sizeof(seed));
45
46 writel_relaxed(seed, hrng->base + RNG_SEED);
47
48 /**
49 * The seed is reload periodically, there are two choice
50 * of seeds, default seed using the value from LFSR, or
51 * will use seed generated by ring oscillator.
52 */
53 if (seed_sel == 1)
54 val |= RNG_RING_EN | RNG_SEED_SEL;
55
56 writel_relaxed(val, hrng->base + RNG_CTRL);
57 return 0;
58 }
59
hisi_rng_cleanup(struct hwrng * rng)60 static void hisi_rng_cleanup(struct hwrng *rng)
61 {
62 struct hisi_rng *hrng = to_hisi_rng(rng);
63
64 writel_relaxed(0, hrng->base + RNG_CTRL);
65 }
66
hisi_rng_read(struct hwrng * rng,void * buf,size_t max,bool wait)67 static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
68 {
69 struct hisi_rng *hrng = to_hisi_rng(rng);
70 u32 *data = buf;
71
72 *data = readl_relaxed(hrng->base + RNG_RAN_NUM);
73 return 4;
74 }
75
hisi_rng_probe(struct platform_device * pdev)76 static int hisi_rng_probe(struct platform_device *pdev)
77 {
78 struct hisi_rng *rng;
79 struct resource *res;
80 int ret;
81
82 rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
83 if (!rng)
84 return -ENOMEM;
85
86 platform_set_drvdata(pdev, rng);
87
88 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
89 rng->base = devm_ioremap_resource(&pdev->dev, res);
90 if (IS_ERR(rng->base))
91 return PTR_ERR(rng->base);
92
93 rng->rng.name = pdev->name;
94 rng->rng.init = hisi_rng_init;
95 rng->rng.cleanup = hisi_rng_cleanup;
96 rng->rng.read = hisi_rng_read;
97
98 ret = devm_hwrng_register(&pdev->dev, &rng->rng);
99 if (ret) {
100 dev_err(&pdev->dev, "failed to register hwrng\n");
101 return ret;
102 }
103
104 return 0;
105 }
106
107 static const struct of_device_id hisi_rng_dt_ids[] = {
108 { .compatible = "hisilicon,hip04-rng" },
109 { .compatible = "hisilicon,hip05-rng" },
110 { }
111 };
112 MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
113
114 static struct platform_driver hisi_rng_driver = {
115 .probe = hisi_rng_probe,
116 .driver = {
117 .name = "hisi-rng",
118 .of_match_table = of_match_ptr(hisi_rng_dt_ids),
119 },
120 };
121
122 module_platform_driver(hisi_rng_driver);
123
124 MODULE_LICENSE("GPL");
125 MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
126 MODULE_DESCRIPTION("Hisilicon random number generator driver");
127