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/io.h>
26 #include <linux/platform_device.h>
27 #include <linux/clk.h>
28 #include <linux/pm_runtime.h>
29 #include <linux/err.h>
30
31 #define EXYNOS_PRNG_STATUS_OFFSET 0x10
32 #define EXYNOS_PRNG_SEED_OFFSET 0x140
33 #define EXYNOS_PRNG_OUT1_OFFSET 0x160
34 #define SEED_SETTING_DONE BIT(1)
35 #define PRNG_START 0x18
36 #define PRNG_DONE BIT(5)
37 #define EXYNOS_AUTOSUSPEND_DELAY 100
38
39 struct exynos_rng {
40 struct device *dev;
41 struct hwrng rng;
42 void __iomem *mem;
43 struct clk *clk;
44 };
45
exynos_rng_readl(struct exynos_rng * rng,u32 offset)46 static u32 exynos_rng_readl(struct exynos_rng *rng, u32 offset)
47 {
48 return __raw_readl(rng->mem + offset);
49 }
50
exynos_rng_writel(struct exynos_rng * rng,u32 val,u32 offset)51 static void exynos_rng_writel(struct exynos_rng *rng, u32 val, u32 offset)
52 {
53 __raw_writel(val, rng->mem + offset);
54 }
55
exynos_init(struct hwrng * rng)56 static int exynos_init(struct hwrng *rng)
57 {
58 struct exynos_rng *exynos_rng = container_of(rng,
59 struct exynos_rng, rng);
60 int i;
61 int ret = 0;
62
63 pm_runtime_get_sync(exynos_rng->dev);
64
65 for (i = 0 ; i < 5 ; i++)
66 exynos_rng_writel(exynos_rng, jiffies,
67 EXYNOS_PRNG_SEED_OFFSET + 4*i);
68
69 if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET)
70 & SEED_SETTING_DONE))
71 ret = -EIO;
72
73 pm_runtime_put_noidle(exynos_rng->dev);
74
75 return ret;
76 }
77
exynos_read(struct hwrng * rng,void * buf,size_t max,bool wait)78 static int exynos_read(struct hwrng *rng, void *buf,
79 size_t max, bool wait)
80 {
81 struct exynos_rng *exynos_rng = container_of(rng,
82 struct exynos_rng, rng);
83 u32 *data = buf;
84
85 pm_runtime_get_sync(exynos_rng->dev);
86
87 exynos_rng_writel(exynos_rng, PRNG_START, 0);
88
89 while (!(exynos_rng_readl(exynos_rng,
90 EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE))
91 cpu_relax();
92
93 exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
94
95 *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
96
97 pm_runtime_mark_last_busy(exynos_rng->dev);
98 pm_runtime_autosuspend(exynos_rng->dev);
99
100 return 4;
101 }
102
exynos_rng_probe(struct platform_device * pdev)103 static int exynos_rng_probe(struct platform_device *pdev)
104 {
105 struct exynos_rng *exynos_rng;
106 struct resource *res;
107
108 exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng),
109 GFP_KERNEL);
110 if (!exynos_rng)
111 return -ENOMEM;
112
113 exynos_rng->dev = &pdev->dev;
114 exynos_rng->rng.name = "exynos";
115 exynos_rng->rng.init = exynos_init;
116 exynos_rng->rng.read = exynos_read;
117 exynos_rng->clk = devm_clk_get(&pdev->dev, "secss");
118 if (IS_ERR(exynos_rng->clk)) {
119 dev_err(&pdev->dev, "Couldn't get clock.\n");
120 return -ENOENT;
121 }
122
123 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
124 exynos_rng->mem = devm_ioremap_resource(&pdev->dev, res);
125 if (IS_ERR(exynos_rng->mem))
126 return PTR_ERR(exynos_rng->mem);
127
128 platform_set_drvdata(pdev, exynos_rng);
129
130 pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY);
131 pm_runtime_use_autosuspend(&pdev->dev);
132 pm_runtime_enable(&pdev->dev);
133
134 return hwrng_register(&exynos_rng->rng);
135 }
136
exynos_rng_remove(struct platform_device * pdev)137 static int exynos_rng_remove(struct platform_device *pdev)
138 {
139 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
140
141 hwrng_unregister(&exynos_rng->rng);
142
143 return 0;
144 }
145
146 #if defined(CONFIG_PM_SLEEP) || defined(CONFIG_PM_RUNTIME)
exynos_rng_runtime_suspend(struct device * dev)147 static 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
exynos_rng_runtime_resume(struct device * dev)157 static 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 #endif
165
166 static UNIVERSAL_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_runtime_suspend,
167 exynos_rng_runtime_resume, NULL);
168
169 static 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
179 module_platform_driver(exynos_rng_driver);
180
181 MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver");
182 MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
183 MODULE_LICENSE("GPL");
184