summaryrefslogtreecommitdiffstats
path: root/drivers/char/hw_random/meson-rng.c
blob: 75225eb9fef6265a03d72f62fa0a07a63b548a5f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
 * Copyright (c) 2016 BayLibre, SAS.
 * Author: Neil Armstrong <narmstrong@baylibre.com>
 * Copyright (C) 2014 Amlogic, Inc.
 */
#include <linux/err.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/of.h>
#include <linux/clk.h>
#include <linux/iopoll.h>

#define RNG_DATA	0x00
#define RNG_S4_DATA	0x08
#define RNG_S4_CFG	0x00

#define RUN_BIT		BIT(0)
#define SEED_READY_STS_BIT	BIT(31)

struct meson_rng_priv {
	int (*read)(struct hwrng *rng, void *buf, size_t max, bool wait);
};

struct meson_rng_data {
	void __iomem *base;
	struct hwrng rng;
	struct device *dev;
};

static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
	struct meson_rng_data *data =
			container_of(rng, struct meson_rng_data, rng);

	*(u32 *)buf = readl_relaxed(data->base + RNG_DATA);

	return sizeof(u32);
}

static int meson_rng_wait_status(void __iomem *cfg_addr, int bit)
{
	u32 status = 0;
	int ret;

	ret = readl_relaxed_poll_timeout_atomic(cfg_addr,
						status, !(status & bit),
						10, 10000);
	if (ret)
		return -EBUSY;

	return 0;
}

static int meson_s4_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
	struct meson_rng_data *data =
			container_of(rng, struct meson_rng_data, rng);

	void __iomem *cfg_addr = data->base + RNG_S4_CFG;
	int err;

	writel_relaxed(readl_relaxed(cfg_addr) | SEED_READY_STS_BIT, cfg_addr);

	err = meson_rng_wait_status(cfg_addr, SEED_READY_STS_BIT);
	if (err) {
		dev_err(data->dev, "Seed isn't ready, try again\n");
		return err;
	}

	err = meson_rng_wait_status(cfg_addr, RUN_BIT);
	if (err) {
		dev_err(data->dev, "Can't get random number, try again\n");
		return err;
	}

	*(u32 *)buf = readl_relaxed(data->base + RNG_S4_DATA);

	return sizeof(u32);
}

static int meson_rng_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct meson_rng_data *data;
	struct clk *core_clk;
	const struct meson_rng_priv *priv;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	priv = device_get_match_data(&pdev->dev);
	if (!priv)
		return -ENODEV;

	data->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(data->base))
		return PTR_ERR(data->base);

	core_clk = devm_clk_get_optional_enabled(dev, "core");
	if (IS_ERR(core_clk))
		return dev_err_probe(dev, PTR_ERR(core_clk),
				     "Failed to get core clock\n");

	data->rng.name = pdev->name;
	data->rng.read = priv->read;

	data->dev = &pdev->dev;

	return devm_hwrng_register(dev, &data->rng);
}

static const struct meson_rng_priv meson_rng_priv = {
	.read = meson_rng_read,
};

static const struct meson_rng_priv meson_rng_priv_s4 = {
	.read = meson_s4_rng_read,
};

static const struct of_device_id meson_rng_of_match[] = {
	{
		.compatible = "amlogic,meson-rng",
		.data = (void *)&meson_rng_priv,
	},
	{
		.compatible = "amlogic,meson-s4-rng",
		.data = (void *)&meson_rng_priv_s4,
	},
	{},
};
MODULE_DEVICE_TABLE(of, meson_rng_of_match);

static struct platform_driver meson_rng_driver = {
	.probe	= meson_rng_probe,
	.driver	= {
		.name = "meson-rng",
		.of_match_table = meson_rng_of_match,
	},
};

module_platform_driver(meson_rng_driver);

MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
MODULE_LICENSE("Dual BSD/GPL");