1/*
2 * RNG driver for Moschip MCS814x SoC
3 *
4 * Copyright 2012 (C), Florian Fainelli <florian@openwrt.org>
5 *
6 * This file is licensed under  the terms of the GNU General Public
7 * License version 2. This program is licensed "as is" without any
8 * warranty of any kind, whether express or implied.
9 */
10
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/module.h>
14#include <linux/types.h>
15#include <linux/platform_device.h>
16#include <linux/hw_random.h>
17#include <linux/io.h>
18#include <linux/of.h>
19
20#define STAT	0x00
21#define RND	0x04
22
23struct mcs814x_rng_priv {
24	void __iomem	*regs;
25};
26
27static int mcs814x_rng_data_read(struct hwrng *rng, u32 *buffer)
28{
29	struct mcs814x_rng_priv *priv = (struct mcs814x_rng_priv *)rng->priv;
30
31	*buffer = readl_relaxed(priv->regs + RND);
32
33	return 4;
34}
35
36static int mcs814x_rng_probe(struct platform_device *pdev)
37{
38	struct resource *res;
39	struct mcs814x_rng_priv *priv;
40	struct hwrng *rng;
41	int ret;
42
43	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
44	if (!res)
45		return -ENODEV;
46
47	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
48	if (!priv) {
49		ret = -ENOMEM;
50		goto out;
51	}
52
53	rng = kzalloc(sizeof(*rng), GFP_KERNEL);
54	if (!rng) {
55		ret = -ENOMEM;
56		goto out_priv;
57	}
58
59	platform_set_drvdata(pdev, rng);
60	rng->priv = (unsigned long)priv;
61	rng->name = pdev->name;
62	rng->data_read = mcs814x_rng_data_read;
63
64	priv->regs = devm_ioremap_resource(&pdev->dev, res);
65	if (!priv->regs) {
66		ret = -ENOMEM;
67		goto out_rng;
68	}
69
70	ret = hwrng_register(rng);
71	if (ret) {
72		dev_err(&pdev->dev, "failed to register hwrng driver\n");
73		goto out;
74	}
75
76	dev_info(&pdev->dev, "registered\n");
77
78	return ret;
79
80out_rng:
81	platform_set_drvdata(pdev, NULL);
82	kfree(rng);
83out_priv:
84	kfree(priv);
85out:
86	return ret;
87}
88
89static int mcs814x_rng_remove(struct platform_device *pdev)
90{
91	struct hwrng *rng = platform_get_drvdata(pdev);
92	struct mcs814x_rng_priv *priv = (struct mcs814x_rng_priv *)rng->priv;
93
94	hwrng_unregister(rng);
95	kfree(priv);
96	kfree(rng);
97	platform_set_drvdata(pdev, NULL);
98
99	return 0;
100}
101
102static const struct of_device_id mcs814x_rng_ids[] = {
103	{ .compatible = "moschip,mcs814x-rng", },
104	{ /* sentinel */ },
105};
106
107static struct platform_driver mcs814x_rng_driver = {
108	.driver	= {
109		.name	= "mcs814x-rng",
110		.owner	= THIS_MODULE,
111		.of_match_table = mcs814x_rng_ids,
112	},
113	.probe	= mcs814x_rng_probe,
114	.remove	= mcs814x_rng_remove,
115};
116
117module_platform_driver(mcs814x_rng_driver);
118
119MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
120MODULE_DESCRIPTION("H/W Random Number Generator (RNG) for Moschip MCS814x");
121MODULE_LICENSE("GPL");
122