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/of_device.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_RDY_CLR					BIT(12)
26 #define CFG_INT_MASK				BIT(11)
27 #define CFG_GEN_EN					BIT(0)
28 
29 /* bits within the STATUS register */
30 #define STATUS_RANDOM_RDY			BIT(0)
31 
32 struct ingenic_trng {
33 	void __iomem *base;
34 	struct clk *clk;
35 	struct hwrng rng;
36 };
37 
38 static int ingenic_trng_init(struct hwrng *rng)
39 {
40 	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
41 	unsigned int ctrl;
42 
43 	ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
44 	ctrl |= CFG_GEN_EN;
45 	writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
46 
47 	return 0;
48 }
49 
50 static void ingenic_trng_cleanup(struct hwrng *rng)
51 {
52 	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
53 	unsigned int ctrl;
54 
55 	ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
56 	ctrl &= ~CFG_GEN_EN;
57 	writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
58 }
59 
60 static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
61 {
62 	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
63 	u32 *data = buf;
64 	u32 status;
65 	int ret;
66 
67 	ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
68 				 status & STATUS_RANDOM_RDY, 10, 1000);
69 	if (ret == -ETIMEDOUT) {
70 		pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
71 		return ret;
72 	}
73 
74 	*data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
75 
76 	return 4;
77 }
78 
79 static int ingenic_trng_probe(struct platform_device *pdev)
80 {
81 	struct ingenic_trng *trng;
82 	int ret;
83 
84 	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
85 	if (!trng)
86 		return -ENOMEM;
87 
88 	trng->base = devm_platform_ioremap_resource(pdev, 0);
89 	if (IS_ERR(trng->base)) {
90 		pr_err("%s: Failed to map DTRNG registers\n", __func__);
91 		ret = PTR_ERR(trng->base);
92 		return PTR_ERR(trng->base);
93 	}
94 
95 	trng->clk = devm_clk_get(&pdev->dev, NULL);
96 	if (IS_ERR(trng->clk)) {
97 		ret = PTR_ERR(trng->clk);
98 		pr_crit("%s: Cannot get DTRNG clock\n", __func__);
99 		return PTR_ERR(trng->clk);
100 	}
101 
102 	ret = clk_prepare_enable(trng->clk);
103 	if (ret) {
104 		pr_crit("%s: Unable to enable DTRNG clock\n", __func__);
105 		return ret;
106 	}
107 
108 	trng->rng.name = pdev->name;
109 	trng->rng.init = ingenic_trng_init;
110 	trng->rng.cleanup = ingenic_trng_cleanup;
111 	trng->rng.read = ingenic_trng_read;
112 
113 	ret = hwrng_register(&trng->rng);
114 	if (ret) {
115 		dev_err(&pdev->dev, "Failed to register hwrng\n");
116 		return ret;
117 	}
118 
119 	platform_set_drvdata(pdev, trng);
120 
121 	dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
122 	return 0;
123 }
124 
125 static int ingenic_trng_remove(struct platform_device *pdev)
126 {
127 	struct ingenic_trng *trng = platform_get_drvdata(pdev);
128 	unsigned int ctrl;
129 
130 	hwrng_unregister(&trng->rng);
131 
132 	ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
133 	ctrl &= ~CFG_GEN_EN;
134 	writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
135 
136 	clk_disable_unprepare(trng->clk);
137 
138 	return 0;
139 }
140 
141 static const struct of_device_id ingenic_trng_of_match[] = {
142 	{ .compatible = "ingenic,x1830-dtrng" },
143 	{ /* sentinel */ }
144 };
145 MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
146 
147 static struct platform_driver ingenic_trng_driver = {
148 	.probe		= ingenic_trng_probe,
149 	.remove		= ingenic_trng_remove,
150 	.driver		= {
151 		.name	= "ingenic-trng",
152 		.of_match_table = ingenic_trng_of_match,
153 	},
154 };
155 
156 module_platform_driver(ingenic_trng_driver);
157 
158 MODULE_LICENSE("GPL");
159 MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
160 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
161 MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");
162