1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Ingenic Random Number Generator driver
4 * Copyright (c) 2017 PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
5 * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
6 */
7
8 #include <linux/err.h>
9 #include <linux/kernel.h>
10 #include <linux/hw_random.h>
11 #include <linux/io.h>
12 #include <linux/iopoll.h>
13 #include <linux/module.h>
14 #include <linux/of_device.h>
15 #include <linux/platform_device.h>
16 #include <linux/slab.h>
17
18 /* RNG register offsets */
19 #define RNG_REG_ERNG_OFFSET 0x0
20 #define RNG_REG_RNG_OFFSET 0x4
21
22 /* bits within the ERND register */
23 #define ERNG_READY BIT(31)
24 #define ERNG_ENABLE BIT(0)
25
26 enum ingenic_rng_version {
27 ID_JZ4780,
28 ID_X1000,
29 };
30
31 /* Device associated memory */
32 struct ingenic_rng {
33 enum ingenic_rng_version version;
34
35 void __iomem *base;
36 struct hwrng rng;
37 };
38
ingenic_rng_init(struct hwrng * rng)39 static int ingenic_rng_init(struct hwrng *rng)
40 {
41 struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
42
43 writel(ERNG_ENABLE, priv->base + RNG_REG_ERNG_OFFSET);
44
45 return 0;
46 }
47
ingenic_rng_cleanup(struct hwrng * rng)48 static void ingenic_rng_cleanup(struct hwrng *rng)
49 {
50 struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
51
52 writel(0, priv->base + RNG_REG_ERNG_OFFSET);
53 }
54
ingenic_rng_read(struct hwrng * rng,void * buf,size_t max,bool wait)55 static int ingenic_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
56 {
57 struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
58 u32 *data = buf;
59 u32 status;
60 int ret;
61
62 if (priv->version >= ID_X1000) {
63 ret = readl_poll_timeout(priv->base + RNG_REG_ERNG_OFFSET, status,
64 status & ERNG_READY, 10, 1000);
65 if (ret == -ETIMEDOUT) {
66 pr_err("%s: Wait for RNG data ready timeout\n", __func__);
67 return ret;
68 }
69 } else {
70 /*
71 * A delay is required so that the current RNG data is not bit shifted
72 * version of previous RNG data which could happen if random data is
73 * read continuously from this device.
74 */
75 udelay(20);
76 }
77
78 *data = readl(priv->base + RNG_REG_RNG_OFFSET);
79
80 return 4;
81 }
82
ingenic_rng_probe(struct platform_device * pdev)83 static int ingenic_rng_probe(struct platform_device *pdev)
84 {
85 struct ingenic_rng *priv;
86 int ret;
87
88 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
89 if (!priv)
90 return -ENOMEM;
91
92 priv->base = devm_platform_ioremap_resource(pdev, 0);
93 if (IS_ERR(priv->base)) {
94 pr_err("%s: Failed to map RNG registers\n", __func__);
95 return PTR_ERR(priv->base);
96 }
97
98 priv->version = (enum ingenic_rng_version)(uintptr_t)of_device_get_match_data(&pdev->dev);
99
100 priv->rng.name = pdev->name;
101 priv->rng.init = ingenic_rng_init;
102 priv->rng.cleanup = ingenic_rng_cleanup;
103 priv->rng.read = ingenic_rng_read;
104
105 ret = hwrng_register(&priv->rng);
106 if (ret) {
107 dev_err(&pdev->dev, "Failed to register hwrng\n");
108 return ret;
109 }
110
111 platform_set_drvdata(pdev, priv);
112
113 dev_info(&pdev->dev, "Ingenic RNG driver registered\n");
114 return 0;
115 }
116
ingenic_rng_remove(struct platform_device * pdev)117 static int ingenic_rng_remove(struct platform_device *pdev)
118 {
119 struct ingenic_rng *priv = platform_get_drvdata(pdev);
120
121 hwrng_unregister(&priv->rng);
122
123 writel(0, priv->base + RNG_REG_ERNG_OFFSET);
124
125 return 0;
126 }
127
128 static const struct of_device_id ingenic_rng_of_match[] = {
129 { .compatible = "ingenic,jz4780-rng", .data = (void *) ID_JZ4780 },
130 { .compatible = "ingenic,x1000-rng", .data = (void *) ID_X1000 },
131 { /* sentinel */ }
132 };
133 MODULE_DEVICE_TABLE(of, ingenic_rng_of_match);
134
135 static struct platform_driver ingenic_rng_driver = {
136 .probe = ingenic_rng_probe,
137 .remove = ingenic_rng_remove,
138 .driver = {
139 .name = "ingenic-rng",
140 .of_match_table = ingenic_rng_of_match,
141 },
142 };
143
144 module_platform_driver(ingenic_rng_driver);
145
146 MODULE_LICENSE("GPL");
147 MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>");
148 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
149 MODULE_DESCRIPTION("Ingenic Random Number Generator driver");
150