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/mod_devicetable.h>
15 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/slab.h>
18
19 /* DTRNG register offsets */
20 #define TRNG_REG_CFG_OFFSET 0x00
21 #define TRNG_REG_RANDOMNUM_OFFSET 0x04
22 #define TRNG_REG_STATUS_OFFSET 0x08
23
24 /* bits within the CFG register */
25 #define CFG_GEN_EN BIT(0)
26
27 /* bits within the STATUS register */
28 #define STATUS_RANDOM_RDY BIT(0)
29
30 struct ingenic_trng {
31 void __iomem *base;
32 struct hwrng rng;
33 };
34
ingenic_trng_init(struct hwrng * rng)35 static int ingenic_trng_init(struct hwrng *rng)
36 {
37 struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
38 unsigned int ctrl;
39
40 ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
41 ctrl |= CFG_GEN_EN;
42 writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
43
44 return 0;
45 }
46
ingenic_trng_cleanup(struct hwrng * rng)47 static void ingenic_trng_cleanup(struct hwrng *rng)
48 {
49 struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
50 unsigned int ctrl;
51
52 ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
53 ctrl &= ~CFG_GEN_EN;
54 writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
55 }
56
ingenic_trng_read(struct hwrng * rng,void * buf,size_t max,bool wait)57 static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
58 {
59 struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
60 u32 *data = buf;
61 u32 status;
62 int ret;
63
64 ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
65 status & STATUS_RANDOM_RDY, 10, 1000);
66 if (ret == -ETIMEDOUT) {
67 pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
68 return ret;
69 }
70
71 *data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
72
73 return 4;
74 }
75
ingenic_trng_probe(struct platform_device * pdev)76 static int ingenic_trng_probe(struct platform_device *pdev)
77 {
78 struct ingenic_trng *trng;
79 struct clk *clk;
80 int ret;
81
82 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
83 if (!trng)
84 return -ENOMEM;
85
86 trng->base = devm_platform_ioremap_resource(pdev, 0);
87 if (IS_ERR(trng->base))
88 return dev_err_probe(&pdev->dev, PTR_ERR(trng->base),
89 "%s: Failed to map DTRNG registers\n", __func__);
90
91 clk = devm_clk_get_enabled(&pdev->dev, NULL);
92 if (IS_ERR(clk))
93 return dev_err_probe(&pdev->dev, PTR_ERR(clk),
94 "%s: Cannot get and enable DTRNG clock\n", __func__);
95
96 trng->rng.name = pdev->name;
97 trng->rng.init = ingenic_trng_init;
98 trng->rng.cleanup = ingenic_trng_cleanup;
99 trng->rng.read = ingenic_trng_read;
100
101 ret = devm_hwrng_register(&pdev->dev, &trng->rng);
102 if (ret)
103 return dev_err_probe(&pdev->dev, ret, "Failed to register hwrng\n");
104
105 platform_set_drvdata(pdev, trng);
106
107 dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
108 return 0;
109 }
110
111 static const struct of_device_id ingenic_trng_of_match[] = {
112 { .compatible = "ingenic,x1830-dtrng" },
113 { /* sentinel */ }
114 };
115 MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
116
117 static struct platform_driver ingenic_trng_driver = {
118 .probe = ingenic_trng_probe,
119 .driver = {
120 .name = "ingenic-trng",
121 .of_match_table = ingenic_trng_of_match,
122 },
123 };
124
125 module_platform_driver(ingenic_trng_driver);
126
127 MODULE_LICENSE("GPL");
128 MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
129 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
130 MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");
131