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 ��������� (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.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
26enum ingenic_rng_version {
27	ID_JZ4780,
28	ID_X1000,
29};
30
31/* Device associated memory */
32struct ingenic_rng {
33	enum ingenic_rng_version version;
34
35	void __iomem *base;
36	struct hwrng rng;
37};
38
39static 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
48static 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
55static 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
83static 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
117static void 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
126static const struct of_device_id ingenic_rng_of_match[] = {
127	{ .compatible = "ingenic,jz4780-rng", .data = (void *) ID_JZ4780 },
128	{ .compatible = "ingenic,x1000-rng", .data = (void *) ID_X1000 },
129	{ /* sentinel */ }
130};
131MODULE_DEVICE_TABLE(of, ingenic_rng_of_match);
132
133static struct platform_driver ingenic_rng_driver = {
134	.probe		= ingenic_rng_probe,
135	.remove_new	= ingenic_rng_remove,
136	.driver		= {
137		.name	= "ingenic-rng",
138		.of_match_table = ingenic_rng_of_match,
139	},
140};
141
142module_platform_driver(ingenic_rng_driver);
143
144MODULE_LICENSE("GPL");
145MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>");
146MODULE_AUTHOR("��������� (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
147MODULE_DESCRIPTION("Ingenic Random Number Generator driver");
148