1 /*
2 * Driver for Mediatek Hardware Random Number Generator
3 *
4 * Copyright (C) 2017 Sean Wang <sean.wang@mediatek.com>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation; either version 2 of
9 * the License, or (at your option) any later version.
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 #define MTK_RNG_DEV KBUILD_MODNAME
17
18 #include <linux/clk.h>
19 #include <linux/delay.h>
20 #include <linux/err.h>
21 #include <linux/hw_random.h>
22 #include <linux/io.h>
23 #include <linux/iopoll.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/of.h>
27 #include <linux/platform_device.h>
28 #include <linux/pm_runtime.h>
29
30 /* Runtime PM autosuspend timeout: */
31 #define RNG_AUTOSUSPEND_TIMEOUT 100
32
33 #define USEC_POLL 2
34 #define TIMEOUT_POLL 20
35
36 #define RNG_CTRL 0x00
37 #define RNG_EN BIT(0)
38 #define RNG_READY BIT(31)
39
40 #define RNG_DATA 0x08
41
42 #define to_mtk_rng(p) container_of(p, struct mtk_rng, rng)
43
44 struct mtk_rng {
45 void __iomem *base;
46 struct clk *clk;
47 struct hwrng rng;
48 };
49
mtk_rng_init(struct hwrng * rng)50 static int mtk_rng_init(struct hwrng *rng)
51 {
52 struct mtk_rng *priv = to_mtk_rng(rng);
53 u32 val;
54 int err;
55
56 err = clk_prepare_enable(priv->clk);
57 if (err)
58 return err;
59
60 val = readl(priv->base + RNG_CTRL);
61 val |= RNG_EN;
62 writel(val, priv->base + RNG_CTRL);
63
64 return 0;
65 }
66
mtk_rng_cleanup(struct hwrng * rng)67 static void mtk_rng_cleanup(struct hwrng *rng)
68 {
69 struct mtk_rng *priv = to_mtk_rng(rng);
70 u32 val;
71
72 val = readl(priv->base + RNG_CTRL);
73 val &= ~RNG_EN;
74 writel(val, priv->base + RNG_CTRL);
75
76 clk_disable_unprepare(priv->clk);
77 }
78
mtk_rng_wait_ready(struct hwrng * rng,bool wait)79 static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait)
80 {
81 struct mtk_rng *priv = to_mtk_rng(rng);
82 int ready;
83
84 ready = readl(priv->base + RNG_CTRL) & RNG_READY;
85 if (!ready && wait)
86 readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready,
87 ready & RNG_READY, USEC_POLL,
88 TIMEOUT_POLL);
89 return !!ready;
90 }
91
mtk_rng_read(struct hwrng * rng,void * buf,size_t max,bool wait)92 static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
93 {
94 struct mtk_rng *priv = to_mtk_rng(rng);
95 int retval = 0;
96
97 pm_runtime_get_sync((struct device *)priv->rng.priv);
98
99 while (max >= sizeof(u32)) {
100 if (!mtk_rng_wait_ready(rng, wait))
101 break;
102
103 *(u32 *)buf = readl(priv->base + RNG_DATA);
104 retval += sizeof(u32);
105 buf += sizeof(u32);
106 max -= sizeof(u32);
107 }
108
109 pm_runtime_mark_last_busy((struct device *)priv->rng.priv);
110 pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv);
111
112 return retval || !wait ? retval : -EIO;
113 }
114
mtk_rng_probe(struct platform_device * pdev)115 static int mtk_rng_probe(struct platform_device *pdev)
116 {
117 struct resource *res;
118 int ret;
119 struct mtk_rng *priv;
120
121 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
122 if (!res) {
123 dev_err(&pdev->dev, "no iomem resource\n");
124 return -ENXIO;
125 }
126
127 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
128 if (!priv)
129 return -ENOMEM;
130
131 priv->rng.name = pdev->name;
132 #ifndef CONFIG_PM
133 priv->rng.init = mtk_rng_init;
134 priv->rng.cleanup = mtk_rng_cleanup;
135 #endif
136 priv->rng.read = mtk_rng_read;
137 priv->rng.priv = (unsigned long)&pdev->dev;
138 priv->rng.quality = 900;
139
140 priv->clk = devm_clk_get(&pdev->dev, "rng");
141 if (IS_ERR(priv->clk)) {
142 ret = PTR_ERR(priv->clk);
143 dev_err(&pdev->dev, "no clock for device: %d\n", ret);
144 return ret;
145 }
146
147 priv->base = devm_ioremap_resource(&pdev->dev, res);
148 if (IS_ERR(priv->base))
149 return PTR_ERR(priv->base);
150
151 ret = devm_hwrng_register(&pdev->dev, &priv->rng);
152 if (ret) {
153 dev_err(&pdev->dev, "failed to register rng device: %d\n",
154 ret);
155 return ret;
156 }
157
158 dev_set_drvdata(&pdev->dev, priv);
159 pm_runtime_set_autosuspend_delay(&pdev->dev, RNG_AUTOSUSPEND_TIMEOUT);
160 pm_runtime_use_autosuspend(&pdev->dev);
161 pm_runtime_enable(&pdev->dev);
162
163 dev_info(&pdev->dev, "registered RNG driver\n");
164
165 return 0;
166 }
167
168 #ifdef CONFIG_PM
mtk_rng_runtime_suspend(struct device * dev)169 static int mtk_rng_runtime_suspend(struct device *dev)
170 {
171 struct mtk_rng *priv = dev_get_drvdata(dev);
172
173 mtk_rng_cleanup(&priv->rng);
174
175 return 0;
176 }
177
mtk_rng_runtime_resume(struct device * dev)178 static int mtk_rng_runtime_resume(struct device *dev)
179 {
180 struct mtk_rng *priv = dev_get_drvdata(dev);
181
182 return mtk_rng_init(&priv->rng);
183 }
184
185 static UNIVERSAL_DEV_PM_OPS(mtk_rng_pm_ops, mtk_rng_runtime_suspend,
186 mtk_rng_runtime_resume, NULL);
187 #define MTK_RNG_PM_OPS (&mtk_rng_pm_ops)
188 #else /* CONFIG_PM */
189 #define MTK_RNG_PM_OPS NULL
190 #endif /* CONFIG_PM */
191
192 static const struct of_device_id mtk_rng_match[] = {
193 { .compatible = "mediatek,mt7623-rng" },
194 {},
195 };
196 MODULE_DEVICE_TABLE(of, mtk_rng_match);
197
198 static struct platform_driver mtk_rng_driver = {
199 .probe = mtk_rng_probe,
200 .driver = {
201 .name = MTK_RNG_DEV,
202 .pm = MTK_RNG_PM_OPS,
203 .of_match_table = mtk_rng_match,
204 },
205 };
206
207 module_platform_driver(mtk_rng_driver);
208
209 MODULE_DESCRIPTION("Mediatek Random Number Generator Driver");
210 MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
211 MODULE_LICENSE("GPL");
212
