1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Ingenic Random Number Generator driver 4 * Copyright (c) 2017 PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> 5 * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> 6 */ 7 8 #include <linux/err.h> 9 #include <linux/kernel.h> 10 #include <linux/hw_random.h> 11 #include <linux/io.h> 12 #include <linux/iopoll.h> 13 #include <linux/module.h> 14 #include <linux/of_device.h> 15 #include <linux/platform_device.h> 16 #include <linux/slab.h> 17 18 /* RNG register offsets */ 19 #define RNG_REG_ERNG_OFFSET 0x0 20 #define RNG_REG_RNG_OFFSET 0x4 21 22 /* bits within the ERND register */ 23 #define ERNG_READY BIT(31) 24 #define ERNG_ENABLE BIT(0) 25 26 enum ingenic_rng_version { 27 ID_JZ4780, 28 ID_X1000, 29 }; 30 31 /* Device associated memory */ 32 struct ingenic_rng { 33 enum ingenic_rng_version version; 34 35 void __iomem *base; 36 struct hwrng rng; 37 }; 38 39 static int ingenic_rng_init(struct hwrng *rng) 40 { 41 struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng); 42 43 writel(ERNG_ENABLE, priv->base + RNG_REG_ERNG_OFFSET); 44 45 return 0; 46 } 47 48 static void ingenic_rng_cleanup(struct hwrng *rng) 49 { 50 struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng); 51 52 writel(0, priv->base + RNG_REG_ERNG_OFFSET); 53 } 54 55 static int ingenic_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) 56 { 57 struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng); 58 u32 *data = buf; 59 u32 status; 60 int ret; 61 62 if (priv->version >= ID_X1000) { 63 ret = readl_poll_timeout(priv->base + RNG_REG_ERNG_OFFSET, status, 64 status & ERNG_READY, 10, 1000); 65 if (ret == -ETIMEDOUT) { 66 pr_err("%s: Wait for RNG data ready timeout\n", __func__); 67 return ret; 68 } 69 } else { 70 /* 71 * A delay is required so that the current RNG data is not bit shifted 72 * version of previous RNG data which could happen if random data is 73 * read continuously from this device. 74 */ 75 udelay(20); 76 } 77 78 *data = readl(priv->base + RNG_REG_RNG_OFFSET); 79 80 return 4; 81 } 82 83 static int ingenic_rng_probe(struct platform_device *pdev) 84 { 85 struct ingenic_rng *priv; 86 int ret; 87 88 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); 89 if (!priv) 90 return -ENOMEM; 91 92 priv->base = devm_platform_ioremap_resource(pdev, 0); 93 if (IS_ERR(priv->base)) { 94 pr_err("%s: Failed to map RNG registers\n", __func__); 95 return PTR_ERR(priv->base); 96 } 97 98 priv->version = (enum ingenic_rng_version)of_device_get_match_data(&pdev->dev); 99 100 priv->rng.name = pdev->name; 101 priv->rng.init = ingenic_rng_init; 102 priv->rng.cleanup = ingenic_rng_cleanup; 103 priv->rng.read = ingenic_rng_read; 104 105 ret = hwrng_register(&priv->rng); 106 if (ret) { 107 dev_err(&pdev->dev, "Failed to register hwrng\n"); 108 return ret; 109 } 110 111 platform_set_drvdata(pdev, priv); 112 113 dev_info(&pdev->dev, "Ingenic RNG driver registered\n"); 114 return 0; 115 } 116 117 static int ingenic_rng_remove(struct platform_device *pdev) 118 { 119 struct ingenic_rng *priv = platform_get_drvdata(pdev); 120 121 hwrng_unregister(&priv->rng); 122 123 writel(0, priv->base + RNG_REG_ERNG_OFFSET); 124 125 return 0; 126 } 127 128 static const struct of_device_id ingenic_rng_of_match[] = { 129 { .compatible = "ingenic,jz4780-rng", .data = (void *) ID_JZ4780 }, 130 { .compatible = "ingenic,x1000-rng", .data = (void *) ID_X1000 }, 131 { /* sentinel */ } 132 }; 133 MODULE_DEVICE_TABLE(of, ingenic_rng_of_match); 134 135 static struct platform_driver ingenic_rng_driver = { 136 .probe = ingenic_rng_probe, 137 .remove = ingenic_rng_remove, 138 .driver = { 139 .name = "ingenic-rng", 140 .of_match_table = ingenic_rng_of_match, 141 }, 142 }; 143 144 module_platform_driver(ingenic_rng_driver); 145 146 MODULE_LICENSE("GPL"); 147 MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>"); 148 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>"); 149 MODULE_DESCRIPTION("Ingenic Random Number Generator driver"); 150