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 
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 
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 
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 
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