2 * Driver for Mediatek Hardware Random Number Generator
4 * Copyright (C) 2017 Sean Wang <sean.wang@mediatek.com>
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.
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.
16 #define MTK_RNG_DEV KBUILD_MODNAME
18 #include <linux/clk.h>
19 #include <linux/delay.h>
20 #include <linux/err.h>
21 #include <linux/hw_random.h>
23 #include <linux/iopoll.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
27 #include <linux/platform_device.h>
28 #include <linux/pm_runtime.h>
30 /* Runtime PM autosuspend timeout: */
31 #define RNG_AUTOSUSPEND_TIMEOUT 100
34 #define TIMEOUT_POLL 20
38 #define RNG_READY BIT(31)
42 #define to_mtk_rng(p) container_of(p, struct mtk_rng, rng)
50 static int mtk_rng_init(struct hwrng *rng)
52 struct mtk_rng *priv = to_mtk_rng(rng);
56 err = clk_prepare_enable(priv->clk);
60 val = readl(priv->base + RNG_CTRL);
62 writel(val, priv->base + RNG_CTRL);
67 static void mtk_rng_cleanup(struct hwrng *rng)
69 struct mtk_rng *priv = to_mtk_rng(rng);
72 val = readl(priv->base + RNG_CTRL);
74 writel(val, priv->base + RNG_CTRL);
76 clk_disable_unprepare(priv->clk);
79 static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait)
81 struct mtk_rng *priv = to_mtk_rng(rng);
84 ready = readl(priv->base + RNG_CTRL) & RNG_READY;
86 readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready,
87 ready & RNG_READY, USEC_POLL,
92 static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
94 struct mtk_rng *priv = to_mtk_rng(rng);
97 pm_runtime_get_sync((struct device *)priv->rng.priv);
99 while (max >= sizeof(u32)) {
100 if (!mtk_rng_wait_ready(rng, wait))
103 *(u32 *)buf = readl(priv->base + RNG_DATA);
104 retval += sizeof(u32);
109 pm_runtime_mark_last_busy((struct device *)priv->rng.priv);
110 pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv);
112 return retval || !wait ? retval : -EIO;
115 static int mtk_rng_probe(struct platform_device *pdev)
117 struct resource *res;
119 struct mtk_rng *priv;
121 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
123 dev_err(&pdev->dev, "no iomem resource\n");
127 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
131 priv->rng.name = pdev->name;
133 priv->rng.init = mtk_rng_init;
134 priv->rng.cleanup = mtk_rng_cleanup;
136 priv->rng.read = mtk_rng_read;
137 priv->rng.priv = (unsigned long)&pdev->dev;
138 priv->rng.quality = 900;
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);
147 priv->base = devm_ioremap_resource(&pdev->dev, res);
148 if (IS_ERR(priv->base))
149 return PTR_ERR(priv->base);
151 ret = devm_hwrng_register(&pdev->dev, &priv->rng);
153 dev_err(&pdev->dev, "failed to register rng device: %d\n",
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);
163 dev_info(&pdev->dev, "registered RNG driver\n");
169 static int mtk_rng_runtime_suspend(struct device *dev)
171 struct mtk_rng *priv = dev_get_drvdata(dev);
173 mtk_rng_cleanup(&priv->rng);
178 static int mtk_rng_runtime_resume(struct device *dev)
180 struct mtk_rng *priv = dev_get_drvdata(dev);
182 return mtk_rng_init(&priv->rng);
185 static const struct dev_pm_ops mtk_rng_pm_ops = {
186 SET_RUNTIME_PM_OPS(mtk_rng_runtime_suspend,
187 mtk_rng_runtime_resume, NULL)
188 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
189 pm_runtime_force_resume)
192 #define MTK_RNG_PM_OPS (&mtk_rng_pm_ops)
193 #else /* CONFIG_PM */
194 #define MTK_RNG_PM_OPS NULL
195 #endif /* CONFIG_PM */
197 static const struct of_device_id mtk_rng_match[] = {
198 { .compatible = "mediatek,mt7623-rng" },
201 MODULE_DEVICE_TABLE(of, mtk_rng_match);
203 static struct platform_driver mtk_rng_driver = {
204 .probe = mtk_rng_probe,
207 .pm = MTK_RNG_PM_OPS,
208 .of_match_table = mtk_rng_match,
212 module_platform_driver(mtk_rng_driver);
214 MODULE_DESCRIPTION("Mediatek Random Number Generator Driver");
215 MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
216 MODULE_LICENSE("GPL");