aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/hw_random/pasemi-rng.c
blob: c66279bb6ef372823afea9a6d36be798c3cb744c (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
153
154
155
156
/*
 * Copyright (C) 2006-2007 PA Semi, Inc
 *
 * Maintained by: Olof Johansson <olof@lixom.net>
 *
 * Driver for the PWRficient onchip rng
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <asm/io.h>

#define SDCRNG_CTL_REG			0x00
#define   SDCRNG_CTL_FVLD_M		0x0000f000
#define   SDCRNG_CTL_FVLD_S		12
#define   SDCRNG_CTL_KSZ		0x00000800
#define   SDCRNG_CTL_RSRC_CRG		0x00000010
#define   SDCRNG_CTL_RSRC_RRG		0x00000000
#define   SDCRNG_CTL_CE			0x00000004
#define   SDCRNG_CTL_RE			0x00000002
#define   SDCRNG_CTL_DR			0x00000001
#define   SDCRNG_CTL_SELECT_RRG_RNG	(SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
#define   SDCRNG_CTL_SELECT_CRG_RNG	(SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
#define SDCRNG_VAL_REG			0x20

#define MODULE_NAME "pasemi_rng"

static int pasemi_rng_data_present(struct hwrng *rng, int wait)
{
	void __iomem *rng_regs = (void __iomem *)rng->priv;
	int data, i;

	for (i = 0; i < 20; i++) {
		data = (in_le32(rng_regs + SDCRNG_CTL_REG)
			& SDCRNG_CTL_FVLD_M) ? 1 : 0;
		if (data || !wait)
			break;
		udelay(10);
	}
	return data;
}

static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
{
	void __iomem *rng_regs = (void __iomem *)rng->priv;
	*data = in_le32(rng_regs + SDCRNG_VAL_REG);
	return 4;
}

static int pasemi_rng_init(struct hwrng *rng)
{
	void __iomem *rng_regs = (void __iomem *)rng->priv;
	u32 ctl;

	ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
	out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
	out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);

	return 0;
}

static void pasemi_rng_cleanup(struct hwrng *rng)
{
	void __iomem *rng_regs = (void __iomem *)rng->priv;
	u32 ctl;

	ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
	out_le32(rng_regs + SDCRNG_CTL_REG,
		 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
}

static struct hwrng pasemi_rng = {
	.name		= MODULE_NAME,
	.init		= pasemi_rng_init,
	.cleanup	= pasemi_rng_cleanup,
	.data_present	= pasemi_rng_data_present,
	.data_read	= pasemi_rng_data_read,
};

static int rng_probe(struct platform_device *ofdev)
{
	void __iomem *rng_regs;
	struct device_node *rng_np = ofdev->dev.of_node;
	struct resource res;
	int err = 0;

	err = of_address_to_resource(rng_np, 0, &res);
	if (err)
		return -ENODEV;

	rng_regs = ioremap(res.start, 0x100);

	if (!rng_regs)
		return -ENOMEM;

	pasemi_rng.priv = (unsigned long)rng_regs;

	printk(KERN_INFO "Registering PA Semi RNG\n");

	err = hwrng_register(&pasemi_rng);

	if (err)
		iounmap(rng_regs);

	return err;
}

static int rng_remove(struct platform_device *dev)
{
	void __iomem *rng_regs = (void __iomem *)pasemi_rng.priv;

	hwrng_unregister(&pasemi_rng);
	iounmap(rng_regs);

	return 0;
}

static struct of_device_id rng_match[] = {
	{ .compatible      = "1682m-rng", },
	{ .compatible      = "pasemi,pwrficient-rng", },
	{ },
};

static struct platform_driver rng_driver = {
	.driver = {
		.name = "pasemi-rng",
		.owner = THIS_MODULE,
		.of_match_table = rng_match,
	},
	.probe		= rng_probe,
	.remove		= rng_remove,
};

module_platform_driver(rng_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");