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
32struct ingenic_trng {
33	void __iomem *base;
34	struct clk *clk;
35	struct hwrng rng;
36};
37
38static 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
50static 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
60static 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
79static 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
124err_unprepare_clk:
125	clk_disable_unprepare(trng->clk);
126	return ret;
127}
128
129static 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
145static const struct of_device_id ingenic_trng_of_match[] = {
146	{ .compatible = "ingenic,x1830-dtrng" },
147	{ /* sentinel */ }
148};
149MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
150
151static 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
160module_platform_driver(ingenic_trng_driver);
161
162MODULE_LICENSE("GPL");
163MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
164MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
165MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");
166