1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Ingenic True Random Number Generator driver
4 * Copyright (c) 2019 ��������� (Qi Pengzhen) <aric.pzqi@ingenic.com>
5 * Copyright (c) 2020 ��������� (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/mod_devicetable.h>
15#include <linux/module.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_GEN_EN					BIT(0)
26
27/* bits within the STATUS register */
28#define STATUS_RANDOM_RDY			BIT(0)
29
30struct ingenic_trng {
31	void __iomem *base;
32	struct hwrng rng;
33};
34
35static int ingenic_trng_init(struct hwrng *rng)
36{
37	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
38	unsigned int ctrl;
39
40	ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
41	ctrl |= CFG_GEN_EN;
42	writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
43
44	return 0;
45}
46
47static void ingenic_trng_cleanup(struct hwrng *rng)
48{
49	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
50	unsigned int ctrl;
51
52	ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
53	ctrl &= ~CFG_GEN_EN;
54	writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
55}
56
57static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
58{
59	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
60	u32 *data = buf;
61	u32 status;
62	int ret;
63
64	ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
65				 status & STATUS_RANDOM_RDY, 10, 1000);
66	if (ret == -ETIMEDOUT) {
67		pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
68		return ret;
69	}
70
71	*data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
72
73	return 4;
74}
75
76static int ingenic_trng_probe(struct platform_device *pdev)
77{
78	struct ingenic_trng *trng;
79	struct clk *clk;
80	int ret;
81
82	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
83	if (!trng)
84		return -ENOMEM;
85
86	trng->base = devm_platform_ioremap_resource(pdev, 0);
87	if (IS_ERR(trng->base))
88		return dev_err_probe(&pdev->dev, PTR_ERR(trng->base),
89				     "%s: Failed to map DTRNG registers\n", __func__);
90
91	clk = devm_clk_get_enabled(&pdev->dev, NULL);
92	if (IS_ERR(clk))
93		return dev_err_probe(&pdev->dev, PTR_ERR(clk),
94				     "%s: Cannot get and enable DTRNG clock\n", __func__);
95
96	trng->rng.name = pdev->name;
97	trng->rng.init = ingenic_trng_init;
98	trng->rng.cleanup = ingenic_trng_cleanup;
99	trng->rng.read = ingenic_trng_read;
100
101	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
102	if (ret)
103		return dev_err_probe(&pdev->dev, ret, "Failed to register hwrng\n");
104
105	platform_set_drvdata(pdev, trng);
106
107	dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
108	return 0;
109}
110
111static const struct of_device_id ingenic_trng_of_match[] = {
112	{ .compatible = "ingenic,x1830-dtrng" },
113	{ /* sentinel */ }
114};
115MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
116
117static struct platform_driver ingenic_trng_driver = {
118	.probe		= ingenic_trng_probe,
119	.driver		= {
120		.name	= "ingenic-trng",
121		.of_match_table = ingenic_trng_of_match,
122	},
123};
124
125module_platform_driver(ingenic_trng_driver);
126
127MODULE_LICENSE("GPL");
128MODULE_AUTHOR("��������� (Qi Pengzhen) <aric.pzqi@ingenic.com>");
129MODULE_AUTHOR("��������� (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
130MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");
131