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 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 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 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 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 } 105 106 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 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 } 161 162 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