1/*
2 * drivers/char/hw_random/omap-rng.c
3 *
4 * RNG driver for TI OMAP CPU family
5 *
6 * Author: Deepak Saxena <dsaxena@plexity.net>
7 *
8 * Copyright 2005 (c) MontaVista Software, Inc.
9 *
10 * Mostly based on original driver:
11 *
12 * Copyright (C) 2005 Nokia Corporation
13 * Author: Juha Yrj������<juha.yrjola@nokia.com>
14 *
15 * This file is licensed under  the terms of the GNU General Public
16 * License version 2. This program is licensed "as is" without any
17 * warranty of any kind, whether express or implied.
18 *
19 * TODO:
20 *
21 * - Make status updated be interrupt driven so we don't poll
22 *
23 */
24
25#include <linux/module.h>
26#include <linux/init.h>
27#include <linux/random.h>
28#include <linux/clk.h>
29#include <linux/err.h>
30#include <linux/platform_device.h>
31#include <linux/hw_random.h>
32
33#include <asm/io.h>
34
35#define RNG_OUT_REG		0x00		/* Output register */
36#define RNG_STAT_REG		0x04		/* Status register
37							[0] = STAT_BUSY */
38#define RNG_ALARM_REG		0x24		/* Alarm register
39							[7:0] = ALARM_COUNTER */
40#define RNG_CONFIG_REG		0x28		/* Configuration register
41							[11:6] = RESET_COUNT
42							[5:3]  = RING2_DELAY
43							[2:0]  = RING1_DELAY */
44#define RNG_REV_REG		0x3c		/* Revision register
45							[7:0] = REV_NB */
46#define RNG_MASK_REG		0x40		/* Mask and reset register
47							[2] = IT_EN
48							[1] = SOFTRESET
49							[0] = AUTOIDLE */
50#define RNG_SYSSTATUS		0x44		/* System status
51							[0] = RESETDONE */
52
53static void __iomem *rng_base;
54static struct clk *rng_ick;
55static struct platform_device *rng_dev;
56
57static u32 omap_rng_read_reg(int reg)
58{
59	return __raw_readl(rng_base + reg);
60}
61
62static void omap_rng_write_reg(int reg, u32 val)
63{
64	__raw_writel(val, rng_base + reg);
65}
66
67/* REVISIT: Does the status bit really work on 16xx? */
68static int omap_rng_data_present(struct hwrng *rng)
69{
70	return omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
71}
72
73static int omap_rng_data_read(struct hwrng *rng, u32 *data)
74{
75	*data = omap_rng_read_reg(RNG_OUT_REG);
76
77	return 4;
78}
79
80static struct hwrng omap_rng_ops = {
81	.name		= "omap",
82	.data_present	= omap_rng_data_present,
83	.data_read	= omap_rng_data_read,
84};
85
86static int __init omap_rng_probe(struct platform_device *pdev)
87{
88	struct resource *res, *mem;
89	int ret;
90
91	/*
92	 * A bit ugly, and it will never actually happen but there can
93	 * be only one RNG and this catches any bork
94	 */
95	BUG_ON(rng_dev);
96
97	if (cpu_is_omap24xx()) {
98		rng_ick = clk_get(NULL, "rng_ick");
99		if (IS_ERR(rng_ick)) {
100			dev_err(&pdev->dev, "Could not get rng_ick\n");
101			ret = PTR_ERR(rng_ick);
102			return ret;
103		} else
104			clk_enable(rng_ick);
105	}
106
107	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
108
109	if (!res)
110		return -ENOENT;
111
112	mem = request_mem_region(res->start, res->end - res->start + 1,
113				 pdev->name);
114	if (mem == NULL)
115		return -EBUSY;
116
117	dev_set_drvdata(&pdev->dev, mem);
118	rng_base = (u32 __iomem *)io_p2v(res->start);
119
120	ret = hwrng_register(&omap_rng_ops);
121	if (ret) {
122		release_resource(mem);
123		rng_base = NULL;
124		return ret;
125	}
126
127	dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
128		omap_rng_read_reg(RNG_REV_REG));
129	omap_rng_write_reg(RNG_MASK_REG, 0x1);
130
131	rng_dev = pdev;
132
133	return 0;
134}
135
136static int __exit omap_rng_remove(struct platform_device *pdev)
137{
138	struct resource *mem = dev_get_drvdata(&pdev->dev);
139
140	hwrng_unregister(&omap_rng_ops);
141
142	omap_rng_write_reg(RNG_MASK_REG, 0x0);
143
144	if (cpu_is_omap24xx()) {
145		clk_disable(rng_ick);
146		clk_put(rng_ick);
147	}
148
149	release_resource(mem);
150	rng_base = NULL;
151
152	return 0;
153}
154
155#ifdef CONFIG_PM
156
157static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message)
158{
159	omap_rng_write_reg(RNG_MASK_REG, 0x0);
160	return 0;
161}
162
163static int omap_rng_resume(struct platform_device *pdev)
164{
165	omap_rng_write_reg(RNG_MASK_REG, 0x1);
166	return 0;
167}
168
169#else
170
171#define	omap_rng_suspend	NULL
172#define	omap_rng_resume		NULL
173
174#endif
175
176
177static struct platform_driver omap_rng_driver = {
178	.driver = {
179		.name		= "omap_rng",
180		.owner		= THIS_MODULE,
181	},
182	.probe		= omap_rng_probe,
183	.remove		= __exit_p(omap_rng_remove),
184	.suspend	= omap_rng_suspend,
185	.resume		= omap_rng_resume
186};
187
188static int __init omap_rng_init(void)
189{
190	if (!cpu_is_omap16xx() && !cpu_is_omap24xx())
191		return -ENODEV;
192
193	return platform_driver_register(&omap_rng_driver);
194}
195
196static void __exit omap_rng_exit(void)
197{
198	platform_driver_unregister(&omap_rng_driver);
199}
200
201module_init(omap_rng_init);
202module_exit(omap_rng_exit);
203
204MODULE_AUTHOR("Deepak Saxena (and others)");
205MODULE_LICENSE("GPL");
206