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_rng_configure(struct exynos_rng * exynos_rng)56 static int exynos_rng_configure(struct exynos_rng *exynos_rng)
57 {
58 int i;
59 int ret = 0;
60
61 for (i = 0 ; i < 5 ; i++)
62 exynos_rng_writel(exynos_rng, jiffies,
63 EXYNOS_PRNG_SEED_OFFSET + 4*i);
64
65 if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET)
66 & SEED_SETTING_DONE))
67 ret = -EIO;
68
69 return ret;
70 }
71
exynos_init(struct hwrng * rng)72 static int exynos_init(struct hwrng *rng)
73 {
74 struct exynos_rng *exynos_rng = container_of(rng,
75 struct exynos_rng, rng);
76 int ret = 0;
77
78 pm_runtime_get_sync(exynos_rng->dev);
79 ret = exynos_rng_configure(exynos_rng);
80 pm_runtime_put_noidle(exynos_rng->dev);
81
82 return ret;
83 }
84
exynos_read(struct hwrng * rng,void * buf,size_t max,bool wait)85 static int exynos_read(struct hwrng *rng, void *buf,
86 size_t max, bool wait)
87 {
88 struct exynos_rng *exynos_rng = container_of(rng,
89 struct exynos_rng, rng);
90 u32 *data = buf;
91 int retry = 100;
92 int ret = 4;
93
94 pm_runtime_get_sync(exynos_rng->dev);
95
96 exynos_rng_writel(exynos_rng, PRNG_START, 0);
97
98 while (!(exynos_rng_readl(exynos_rng,
99 EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE) && --retry)
100 cpu_relax();
101 if (!retry) {
102 ret = -ETIMEDOUT;
103 goto out;
104 }
105
106 exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
107
108 *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
109
110 out:
111 pm_runtime_mark_last_busy(exynos_rng->dev);
112 pm_runtime_put_sync_autosuspend(exynos_rng->dev);
113
114 return ret;
115 }
116
exynos_rng_probe(struct platform_device * pdev)117 static int exynos_rng_probe(struct platform_device *pdev)
118 {
119 struct exynos_rng *exynos_rng;
120 struct resource *res;
121 int ret;
122
123 exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng),
124 GFP_KERNEL);
125 if (!exynos_rng)
126 return -ENOMEM;
127
128 exynos_rng->dev = &pdev->dev;
129 exynos_rng->rng.name = "exynos";
130 exynos_rng->rng.init = exynos_init;
131 exynos_rng->rng.read = exynos_read;
132 exynos_rng->clk = devm_clk_get(&pdev->dev, "secss");
133 if (IS_ERR(exynos_rng->clk)) {
134 dev_err(&pdev->dev, "Couldn't get clock.\n");
135 return -ENOENT;
136 }
137
138 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
139 exynos_rng->mem = devm_ioremap_resource(&pdev->dev, res);
140 if (IS_ERR(exynos_rng->mem))
141 return PTR_ERR(exynos_rng->mem);
142
143 platform_set_drvdata(pdev, exynos_rng);
144
145 pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY);
146 pm_runtime_use_autosuspend(&pdev->dev);
147 pm_runtime_enable(&pdev->dev);
148
149 ret = devm_hwrng_register(&pdev->dev, &exynos_rng->rng);
150 if (ret) {
151 pm_runtime_dont_use_autosuspend(&pdev->dev);
152 pm_runtime_disable(&pdev->dev);
153 }
154
155 return ret;
156 }
157
exynos_rng_remove(struct platform_device * pdev)158 static int exynos_rng_remove(struct platform_device *pdev)
159 {
160 pm_runtime_dont_use_autosuspend(&pdev->dev);
161 pm_runtime_disable(&pdev->dev);
162
163 return 0;
164 }
165
exynos_rng_runtime_suspend(struct device * dev)166 static int __maybe_unused exynos_rng_runtime_suspend(struct device *dev)
167 {
168 struct platform_device *pdev = to_platform_device(dev);
169 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
170
171 clk_disable_unprepare(exynos_rng->clk);
172
173 return 0;
174 }
175
exynos_rng_runtime_resume(struct device * dev)176 static int __maybe_unused exynos_rng_runtime_resume(struct device *dev)
177 {
178 struct platform_device *pdev = to_platform_device(dev);
179 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
180
181 return clk_prepare_enable(exynos_rng->clk);
182 }
183
exynos_rng_suspend(struct device * dev)184 static int __maybe_unused exynos_rng_suspend(struct device *dev)
185 {
186 return pm_runtime_force_suspend(dev);
187 }
188
exynos_rng_resume(struct device * dev)189 static int __maybe_unused exynos_rng_resume(struct device *dev)
190 {
191 struct platform_device *pdev = to_platform_device(dev);
192 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
193 int ret;
194
195 ret = pm_runtime_force_resume(dev);
196 if (ret)
197 return ret;
198
199 return exynos_rng_configure(exynos_rng);
200 }
201
202 static const struct dev_pm_ops exynos_rng_pm_ops = {
203 SET_SYSTEM_SLEEP_PM_OPS(exynos_rng_suspend, exynos_rng_resume)
204 SET_RUNTIME_PM_OPS(exynos_rng_runtime_suspend,
205 exynos_rng_runtime_resume, NULL)
206 };
207
208 static const struct of_device_id exynos_rng_dt_match[] = {
209 {
210 .compatible = "samsung,exynos4-rng",
211 },
212 { },
213 };
214 MODULE_DEVICE_TABLE(of, exynos_rng_dt_match);
215
216 static struct platform_driver exynos_rng_driver = {
217 .driver = {
218 .name = "exynos-rng",
219 .pm = &exynos_rng_pm_ops,
220 .of_match_table = exynos_rng_dt_match,
221 },
222 .probe = exynos_rng_probe,
223 .remove = exynos_rng_remove,
224 };
225
226 module_platform_driver(exynos_rng_driver);
227
228 MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver");
229 MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
230 MODULE_LICENSE("GPL");
231