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/drivers/char/hw_random/pasemi-rng.c

https://bitbucket.org/cresqo/cm7-p500-kernel
C | 166 lines | 117 code | 29 blank | 20 comment | 6 complexity | 53cd5e848f2762a074bd3a5c76469231 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 * Copyright (C) 2006-2007 PA Semi, Inc
  3 *
  4 * Maintained by: Olof Johansson <olof@lixom.net>
  5 *
  6 * Driver for the PWRficient onchip rng
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License version 2 as
 10 * published by the Free Software Foundation.
 11 *
 12 * This program is distributed in the hope that it will be useful,
 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15 * GNU General Public License for more details.
 16 *
 17 * You should have received a copy of the GNU General Public License
 18 * along with this program; if not, write to the Free Software
 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 20 */
 21
 22#include <linux/module.h>
 23#include <linux/kernel.h>
 24#include <linux/platform_device.h>
 25#include <linux/hw_random.h>
 26#include <linux/delay.h>
 27#include <linux/of_platform.h>
 28#include <asm/io.h>
 29
 30#define SDCRNG_CTL_REG			0x00
 31#define   SDCRNG_CTL_FVLD_M		0x0000f000
 32#define   SDCRNG_CTL_FVLD_S		12
 33#define   SDCRNG_CTL_KSZ		0x00000800
 34#define   SDCRNG_CTL_RSRC_CRG		0x00000010
 35#define   SDCRNG_CTL_RSRC_RRG		0x00000000
 36#define   SDCRNG_CTL_CE			0x00000004
 37#define   SDCRNG_CTL_RE			0x00000002
 38#define   SDCRNG_CTL_DR			0x00000001
 39#define   SDCRNG_CTL_SELECT_RRG_RNG	(SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
 40#define   SDCRNG_CTL_SELECT_CRG_RNG	(SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
 41#define SDCRNG_VAL_REG			0x20
 42
 43#define MODULE_NAME "pasemi_rng"
 44
 45static int pasemi_rng_data_present(struct hwrng *rng, int wait)
 46{
 47	void __iomem *rng_regs = (void __iomem *)rng->priv;
 48	int data, i;
 49
 50	for (i = 0; i < 20; i++) {
 51		data = (in_le32(rng_regs + SDCRNG_CTL_REG)
 52			& SDCRNG_CTL_FVLD_M) ? 1 : 0;
 53		if (data || !wait)
 54			break;
 55		udelay(10);
 56	}
 57	return data;
 58}
 59
 60static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
 61{
 62	void __iomem *rng_regs = (void __iomem *)rng->priv;
 63	*data = in_le32(rng_regs + SDCRNG_VAL_REG);
 64	return 4;
 65}
 66
 67static int pasemi_rng_init(struct hwrng *rng)
 68{
 69	void __iomem *rng_regs = (void __iomem *)rng->priv;
 70	u32 ctl;
 71
 72	ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
 73	out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
 74	out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
 75
 76	return 0;
 77}
 78
 79static void pasemi_rng_cleanup(struct hwrng *rng)
 80{
 81	void __iomem *rng_regs = (void __iomem *)rng->priv;
 82	u32 ctl;
 83
 84	ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
 85	out_le32(rng_regs + SDCRNG_CTL_REG,
 86		 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
 87}
 88
 89static struct hwrng pasemi_rng = {
 90	.name		= MODULE_NAME,
 91	.init		= pasemi_rng_init,
 92	.cleanup	= pasemi_rng_cleanup,
 93	.data_present	= pasemi_rng_data_present,
 94	.data_read	= pasemi_rng_data_read,
 95};
 96
 97static int __devinit rng_probe(struct of_device *ofdev,
 98			       const struct of_device_id *match)
 99{
100	void __iomem *rng_regs;
101	struct device_node *rng_np = ofdev->dev.of_node;
102	struct resource res;
103	int err = 0;
104
105	err = of_address_to_resource(rng_np, 0, &res);
106	if (err)
107		return -ENODEV;
108
109	rng_regs = ioremap(res.start, 0x100);
110
111	if (!rng_regs)
112		return -ENOMEM;
113
114	pasemi_rng.priv = (unsigned long)rng_regs;
115
116	printk(KERN_INFO "Registering PA Semi RNG\n");
117
118	err = hwrng_register(&pasemi_rng);
119
120	if (err)
121		iounmap(rng_regs);
122
123	return err;
124}
125
126static int __devexit rng_remove(struct of_device *dev)
127{
128	void __iomem *rng_regs = (void __iomem *)pasemi_rng.priv;
129
130	hwrng_unregister(&pasemi_rng);
131	iounmap(rng_regs);
132
133	return 0;
134}
135
136static struct of_device_id rng_match[] = {
137	{ .compatible      = "1682m-rng", },
138	{ .compatible      = "pasemi,pwrficient-rng", },
139	{ },
140};
141
142static struct of_platform_driver rng_driver = {
143	.driver = {
144		.name = "pasemi-rng",
145		.owner = THIS_MODULE,
146		.of_match_table = rng_match,
147	},
148	.probe		= rng_probe,
149	.remove		= rng_remove,
150};
151
152static int __init rng_init(void)
153{
154	return of_register_platform_driver(&rng_driver);
155}
156module_init(rng_init);
157
158static void __exit rng_exit(void)
159{
160	of_unregister_platform_driver(&rng_driver);
161}
162module_exit(rng_exit);
163
164MODULE_LICENSE("GPL");
165MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
166MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");