1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Ingenic True Random Number Generator driver
4 * Copyright (c) 2019 漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>
5 * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
6 */
7
8 #include <linux/clk.h>
9 #include <linux/err.h>
10 #include <linux/kernel.h>
11 #include <linux/hw_random.h>
12 #include <linux/io.h>
13 #include <linux/iopoll.h>
14 #include <linux/module.h>
15 #include <linux/platform_device.h>
16 #include <linux/slab.h>
17
18 /* DTRNG register offsets */
19 #define TRNG_REG_CFG_OFFSET 0x00
20 #define TRNG_REG_RANDOMNUM_OFFSET 0x04
21 #define TRNG_REG_STATUS_OFFSET 0x08
22
23 /* bits within the CFG register */
24 #define CFG_GEN_EN BIT(0)
25
26 /* bits within the STATUS register */
27 #define STATUS_RANDOM_RDY BIT(0)
28
29 struct ingenic_trng {
30 void __iomem *base;
31 struct hwrng rng;
32 };
33
ingenic_trng_init(struct hwrng * rng)34 static int ingenic_trng_init(struct hwrng *rng)
35 {
36 struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
37 unsigned int ctrl;
38
39 ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
40 ctrl |= CFG_GEN_EN;
41 writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
42
43 return 0;
44 }
45
ingenic_trng_cleanup(struct hwrng * rng)46 static void ingenic_trng_cleanup(struct hwrng *rng)
47 {
48 struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
49 unsigned int ctrl;
50
51 ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
52 ctrl &= ~CFG_GEN_EN;
53 writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
54 }
55
ingenic_trng_read(struct hwrng * rng,void * buf,size_t max,bool wait)56 static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
57 {
58 struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
59 u32 *data = buf;
60 u32 status;
61 int ret;
62
63 ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
64 status & STATUS_RANDOM_RDY, 10, 1000);
65 if (ret == -ETIMEDOUT) {
66 pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
67 return ret;
68 }
69
70 *data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
71
72 return 4;
73 }
74
ingenic_trng_probe(struct platform_device * pdev)75 static int ingenic_trng_probe(struct platform_device *pdev)
76 {
77 struct ingenic_trng *trng;
78 struct clk *clk;
79 int ret;
80
81 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
82 if (!trng)
83 return -ENOMEM;
84
85 trng->base = devm_platform_ioremap_resource(pdev, 0);
86 if (IS_ERR(trng->base))
87 return dev_err_probe(&pdev->dev, PTR_ERR(trng->base),
88 "%s: Failed to map DTRNG registers\n", __func__);
89
90 clk = devm_clk_get_enabled(&pdev->dev, NULL);
91 if (IS_ERR(clk))
92 return dev_err_probe(&pdev->dev, PTR_ERR(clk),
93 "%s: Cannot get and enable DTRNG clock\n", __func__);
94
95 trng->rng.name = pdev->name;
96 trng->rng.init = ingenic_trng_init;
97 trng->rng.cleanup = ingenic_trng_cleanup;
98 trng->rng.read = ingenic_trng_read;
99
100 ret = devm_hwrng_register(&pdev->dev, &trng->rng);
101 if (ret)
102 return dev_err_probe(&pdev->dev, ret, "Failed to register hwrng\n");
103
104 platform_set_drvdata(pdev, trng);
105
106 dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
107 return 0;
108 }
109
110 static const struct of_device_id ingenic_trng_of_match[] = {
111 { .compatible = "ingenic,x1830-dtrng" },
112 { /* sentinel */ }
113 };
114 MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
115
116 static struct platform_driver ingenic_trng_driver = {
117 .probe = ingenic_trng_probe,
118 .driver = {
119 .name = "ingenic-trng",
120 .of_match_table = ingenic_trng_of_match,
121 },
122 };
123
124 module_platform_driver(ingenic_trng_driver);
125
126 MODULE_LICENSE("GPL");
127 MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
128 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
129 MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");
130