tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
147#if defined(CONFIG_PM_SLEEP) || defined(CONFIG_PM_RUNTIME)
148static int exynos_rng_runtime_suspend(struct device *dev)
149{
150 struct platform_device *pdev = to_platform_device(dev);
151 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
152
153 clk_disable_unprepare(exynos_rng->clk);
154
155 return 0;
156}
157
158static int exynos_rng_runtime_resume(struct device *dev)
159{
160 struct platform_device *pdev = to_platform_device(dev);
161 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
162
163 return clk_prepare_enable(exynos_rng->clk);
164}
165#endif
166
167static UNIVERSAL_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_runtime_suspend,
168 exynos_rng_runtime_resume, NULL);
169
170static struct platform_driver exynos_rng_driver = {
171 .driver = {
172 .name = "exynos-rng",
173 .owner = THIS_MODULE,
174 .pm = &exynos_rng_pm_ops,
175 },
176 .probe = exynos_rng_probe,
177 .remove = exynos_rng_remove,
178};
179
180module_platform_driver(exynos_rng_driver);
181
182MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver");
183MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
184MODULE_LICENSE("GPL");