Root/drivers/char/hw_random/exynos-rng.c

1/*
2 * exynos-rng.c - Random Number Generator driver for the exynos
3 *
4 * Copyright (C) 2012 Samsung Electronics
5 * Jonghwa Lee <jonghwa3.lee@smasung.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation;
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 *
20 */
21
22#include <linux/hw_random.h>
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/init.h>
26#include <linux/io.h>
27#include <linux/platform_device.h>
28#include <linux/clk.h>
29#include <linux/pm_runtime.h>
30#include <linux/err.h>
31
32#define EXYNOS_PRNG_STATUS_OFFSET 0x10
33#define EXYNOS_PRNG_SEED_OFFSET 0x140
34#define EXYNOS_PRNG_OUT1_OFFSET 0x160
35#define SEED_SETTING_DONE BIT(1)
36#define PRNG_START 0x18
37#define PRNG_DONE BIT(5)
38#define EXYNOS_AUTOSUSPEND_DELAY 100
39
40struct exynos_rng {
41    struct device *dev;
42    struct hwrng rng;
43    void __iomem *mem;
44    struct clk *clk;
45};
46
47static u32 exynos_rng_readl(struct exynos_rng *rng, u32 offset)
48{
49    return __raw_readl(rng->mem + offset);
50}
51
52static void exynos_rng_writel(struct exynos_rng *rng, u32 val, u32 offset)
53{
54    __raw_writel(val, rng->mem + offset);
55}
56
57static int exynos_init(struct hwrng *rng)
58{
59    struct exynos_rng *exynos_rng = container_of(rng,
60                        struct exynos_rng, rng);
61    int i;
62    int ret = 0;
63
64    pm_runtime_get_sync(exynos_rng->dev);
65
66    for (i = 0 ; i < 5 ; i++)
67        exynos_rng_writel(exynos_rng, jiffies,
68                EXYNOS_PRNG_SEED_OFFSET + 4*i);
69
70    if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET)
71                         & SEED_SETTING_DONE))
72        ret = -EIO;
73
74    pm_runtime_put_noidle(exynos_rng->dev);
75
76    return ret;
77}
78
79static int exynos_read(struct hwrng *rng, void *buf,
80                    size_t max, bool wait)
81{
82    struct exynos_rng *exynos_rng = container_of(rng,
83                        struct exynos_rng, rng);
84    u32 *data = buf;
85
86    pm_runtime_get_sync(exynos_rng->dev);
87
88    exynos_rng_writel(exynos_rng, PRNG_START, 0);
89
90    while (!(exynos_rng_readl(exynos_rng,
91            EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE))
92        cpu_relax();
93
94    exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
95
96    *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
97
98    pm_runtime_mark_last_busy(exynos_rng->dev);
99    pm_runtime_autosuspend(exynos_rng->dev);
100
101    return 4;
102}
103
104static int exynos_rng_probe(struct platform_device *pdev)
105{
106    struct exynos_rng *exynos_rng;
107    struct resource *res;
108
109    exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng),
110                    GFP_KERNEL);
111    if (!exynos_rng)
112        return -ENOMEM;
113
114    exynos_rng->dev = &pdev->dev;
115    exynos_rng->rng.name = "exynos";
116    exynos_rng->rng.init = exynos_init;
117    exynos_rng->rng.read = exynos_read;
118    exynos_rng->clk = devm_clk_get(&pdev->dev, "secss");
119    if (IS_ERR(exynos_rng->clk)) {
120        dev_err(&pdev->dev, "Couldn't get clock.\n");
121        return -ENOENT;
122    }
123
124    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
125    exynos_rng->mem = devm_ioremap_resource(&pdev->dev, res);
126    if (IS_ERR(exynos_rng->mem))
127        return PTR_ERR(exynos_rng->mem);
128
129    platform_set_drvdata(pdev, exynos_rng);
130
131    pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY);
132    pm_runtime_use_autosuspend(&pdev->dev);
133    pm_runtime_enable(&pdev->dev);
134
135    return hwrng_register(&exynos_rng->rng);
136}
137
138static int exynos_rng_remove(struct platform_device *pdev)
139{
140    struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
141
142    hwrng_unregister(&exynos_rng->rng);
143
144    return 0;
145}
146
147static int exynos_rng_runtime_suspend(struct device *dev)
148{
149    struct platform_device *pdev = to_platform_device(dev);
150    struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
151
152    clk_disable_unprepare(exynos_rng->clk);
153
154    return 0;
155}
156
157static int exynos_rng_runtime_resume(struct device *dev)
158{
159    struct platform_device *pdev = to_platform_device(dev);
160    struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
161
162    return clk_prepare_enable(exynos_rng->clk);
163}
164
165
166static UNIVERSAL_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_runtime_suspend,
167                    exynos_rng_runtime_resume, NULL);
168
169static struct platform_driver exynos_rng_driver = {
170    .driver = {
171        .name = "exynos-rng",
172        .owner = THIS_MODULE,
173        .pm = &exynos_rng_pm_ops,
174    },
175    .probe = exynos_rng_probe,
176    .remove = exynos_rng_remove,
177};
178
179module_platform_driver(exynos_rng_driver);
180
181MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver");
182MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
183MODULE_LICENSE("GPL");
184

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive