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
ingenic_trng_init(struct hwrng * rng)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
ingenic_trng_cleanup(struct hwrng * rng)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
ingenic_trng_read(struct hwrng * rng,void * buf,size_t max,bool wait)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
ingenic_trng_probe(struct platform_device * pdev)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 goto err_unprepare_clk;
117 }
118
119 platform_set_drvdata(pdev, trng);
120
121 dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
122 return 0;
123
124 err_unprepare_clk:
125 clk_disable_unprepare(trng->clk);
126 return ret;
127 }
128
ingenic_trng_remove(struct platform_device * pdev)129 static int ingenic_trng_remove(struct platform_device *pdev)
130 {
131 struct ingenic_trng *trng = platform_get_drvdata(pdev);
132 unsigned int ctrl;
133
134 hwrng_unregister(&trng->rng);
135
136 ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
137 ctrl &= ~CFG_GEN_EN;
138 writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
139
140 clk_disable_unprepare(trng->clk);
141
142 return 0;
143 }
144
145 static const struct of_device_id ingenic_trng_of_match[] = {
146 { .compatible = "ingenic,x1830-dtrng" },
147 { /* sentinel */ }
148 };
149 MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
150
151 static struct platform_driver ingenic_trng_driver = {
152 .probe = ingenic_trng_probe,
153 .remove = ingenic_trng_remove,
154 .driver = {
155 .name = "ingenic-trng",
156 .of_match_table = ingenic_trng_of_match,
157 },
158 };
159
160 module_platform_driver(ingenic_trng_driver);
161
162 MODULE_LICENSE("GPL");
163 MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
164 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
165 MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");
166