Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial
[linux-2.6] / drivers / char / hw_random / omap-rng.c
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
53 static void __iomem *rng_base;
54 static struct clk *rng_ick;
55 static struct platform_device *rng_dev;
56
57 static u32 omap_rng_read_reg(int reg)
58 {
59         return __raw_readl(rng_base + reg);
60 }
61
62 static 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? */
68 static int omap_rng_data_present(struct hwrng *rng)
69 {
70         return omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
71 }
72
73 static 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
80 static struct hwrng omap_rng_ops = {
81         .name           = "omap",
82         .data_present   = omap_rng_data_present,
83         .data_read      = omap_rng_data_read,
84 };
85
86 static 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
136 static 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
157 static 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
163 static 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
177 static 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
188 static 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
196 static void __exit omap_rng_exit(void)
197 {
198         platform_driver_unregister(&omap_rng_driver);
199 }
200
201 module_init(omap_rng_init);
202 module_exit(omap_rng_exit);
203
204 MODULE_AUTHOR("Deepak Saxena (and others)");
205 MODULE_LICENSE("GPL");