1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Driver for Mediatek Hardware Random Number Generator
4 *
5 * Copyright (C) 2017 Sean Wang <sean.wang@mediatek.com>
6 */
7 #define MTK_RNG_DEV KBUILD_MODNAME
8
9 #include <linux/clk.h>
10 #include <linux/delay.h>
11 #include <linux/err.h>
12 #include <linux/hw_random.h>
13 #include <linux/io.h>
14 #include <linux/iopoll.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/pm_runtime.h>
20
21 /* Runtime PM autosuspend timeout: */
22 #define RNG_AUTOSUSPEND_TIMEOUT 100
23
24 #define USEC_POLL 2
25 #define TIMEOUT_POLL 20
26
27 #define RNG_CTRL 0x00
28 #define RNG_EN BIT(0)
29 #define RNG_READY BIT(31)
30
31 #define RNG_DATA 0x08
32
33 #define to_mtk_rng(p) container_of(p, struct mtk_rng, rng)
34
35 struct mtk_rng {
36 void __iomem *base;
37 struct clk *clk;
38 struct hwrng rng;
39 };
40
mtk_rng_init(struct hwrng * rng)41 static int mtk_rng_init(struct hwrng *rng)
42 {
43 struct mtk_rng *priv = to_mtk_rng(rng);
44 u32 val;
45 int err;
46
47 err = clk_prepare_enable(priv->clk);
48 if (err)
49 return err;
50
51 val = readl(priv->base + RNG_CTRL);
52 val |= RNG_EN;
53 writel(val, priv->base + RNG_CTRL);
54
55 return 0;
56 }
57
mtk_rng_cleanup(struct hwrng * rng)58 static void mtk_rng_cleanup(struct hwrng *rng)
59 {
60 struct mtk_rng *priv = to_mtk_rng(rng);
61 u32 val;
62
63 val = readl(priv->base + RNG_CTRL);
64 val &= ~RNG_EN;
65 writel(val, priv->base + RNG_CTRL);
66
67 clk_disable_unprepare(priv->clk);
68 }
69
mtk_rng_wait_ready(struct hwrng * rng,bool wait)70 static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait)
71 {
72 struct mtk_rng *priv = to_mtk_rng(rng);
73 int ready;
74
75 ready = readl(priv->base + RNG_CTRL) & RNG_READY;
76 if (!ready && wait)
77 readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready,
78 ready & RNG_READY, USEC_POLL,
79 TIMEOUT_POLL);
80 return !!ready;
81 }
82
mtk_rng_read(struct hwrng * rng,void * buf,size_t max,bool wait)83 static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
84 {
85 struct mtk_rng *priv = to_mtk_rng(rng);
86 int retval = 0;
87
88 pm_runtime_get_sync((struct device *)priv->rng.priv);
89
90 while (max >= sizeof(u32)) {
91 if (!mtk_rng_wait_ready(rng, wait))
92 break;
93
94 *(u32 *)buf = readl(priv->base + RNG_DATA);
95 retval += sizeof(u32);
96 buf += sizeof(u32);
97 max -= sizeof(u32);
98 }
99
100 pm_runtime_mark_last_busy((struct device *)priv->rng.priv);
101 pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv);
102
103 return retval || !wait ? retval : -EIO;
104 }
105
mtk_rng_probe(struct platform_device * pdev)106 static int mtk_rng_probe(struct platform_device *pdev)
107 {
108 int ret;
109 struct mtk_rng *priv;
110
111 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
112 if (!priv)
113 return -ENOMEM;
114
115 priv->rng.name = pdev->name;
116 #ifndef CONFIG_PM
117 priv->rng.init = mtk_rng_init;
118 priv->rng.cleanup = mtk_rng_cleanup;
119 #endif
120 priv->rng.read = mtk_rng_read;
121 priv->rng.priv = (unsigned long)&pdev->dev;
122 priv->rng.quality = 900;
123
124 priv->clk = devm_clk_get(&pdev->dev, "rng");
125 if (IS_ERR(priv->clk)) {
126 ret = PTR_ERR(priv->clk);
127 dev_err(&pdev->dev, "no clock for device: %d\n", ret);
128 return ret;
129 }
130
131 priv->base = devm_platform_ioremap_resource(pdev, 0);
132 if (IS_ERR(priv->base))
133 return PTR_ERR(priv->base);
134
135 ret = devm_hwrng_register(&pdev->dev, &priv->rng);
136 if (ret) {
137 dev_err(&pdev->dev, "failed to register rng device: %d\n",
138 ret);
139 return ret;
140 }
141
142 dev_set_drvdata(&pdev->dev, priv);
143 pm_runtime_set_autosuspend_delay(&pdev->dev, RNG_AUTOSUSPEND_TIMEOUT);
144 pm_runtime_use_autosuspend(&pdev->dev);
145 pm_runtime_enable(&pdev->dev);
146
147 dev_info(&pdev->dev, "registered RNG driver\n");
148
149 return 0;
150 }
151
152 #ifdef CONFIG_PM
mtk_rng_runtime_suspend(struct device * dev)153 static int mtk_rng_runtime_suspend(struct device *dev)
154 {
155 struct mtk_rng *priv = dev_get_drvdata(dev);
156
157 mtk_rng_cleanup(&priv->rng);
158
159 return 0;
160 }
161
mtk_rng_runtime_resume(struct device * dev)162 static int mtk_rng_runtime_resume(struct device *dev)
163 {
164 struct mtk_rng *priv = dev_get_drvdata(dev);
165
166 return mtk_rng_init(&priv->rng);
167 }
168
169 static UNIVERSAL_DEV_PM_OPS(mtk_rng_pm_ops, mtk_rng_runtime_suspend,
170 mtk_rng_runtime_resume, NULL);
171 #define MTK_RNG_PM_OPS (&mtk_rng_pm_ops)
172 #else /* CONFIG_PM */
173 #define MTK_RNG_PM_OPS NULL
174 #endif /* CONFIG_PM */
175
176 static const struct of_device_id mtk_rng_match[] = {
177 { .compatible = "mediatek,mt7623-rng" },
178 {},
179 };
180 MODULE_DEVICE_TABLE(of, mtk_rng_match);
181
182 static struct platform_driver mtk_rng_driver = {
183 .probe = mtk_rng_probe,
184 .driver = {
185 .name = MTK_RNG_DEV,
186 .pm = MTK_RNG_PM_OPS,
187 .of_match_table = mtk_rng_match,
188 },
189 };
190
191 module_platform_driver(mtk_rng_driver);
192
193 MODULE_DESCRIPTION("Mediatek Random Number Generator Driver");
194 MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
195 MODULE_LICENSE("GPL");
196
