1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2016 HiSilicon Co., Ltd. 4 */ 5 6 #include <linux/err.h> 7 #include <linux/kernel.h> 8 #include <linux/hw_random.h> 9 #include <linux/io.h> 10 #include <linux/module.h> 11 #include <linux/of.h> 12 #include <linux/platform_device.h> 13 #include <linux/random.h> 14 15 #define RNG_SEED 0x0 16 #define RNG_CTRL 0x4 17 #define RNG_SEED_SEL BIT(2) 18 #define RNG_RING_EN BIT(1) 19 #define RNG_EN BIT(0) 20 #define RNG_RAN_NUM 0x10 21 #define RNG_PHY_SEED 0x14 22 23 #define to_hisi_rng(p) container_of(p, struct hisi_rng, rng) 24 25 static int seed_sel; 26 module_param(seed_sel, int, S_IRUGO); 27 MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator."); 28 29 struct hisi_rng { 30 void __iomem *base; 31 struct hwrng rng; 32 }; 33 34 static int hisi_rng_init(struct hwrng *rng) 35 { 36 struct hisi_rng *hrng = to_hisi_rng(rng); 37 int val = RNG_EN; 38 u32 seed; 39 40 /* get a random number as initial seed */ 41 get_random_bytes(&seed, sizeof(seed)); 42 43 writel_relaxed(seed, hrng->base + RNG_SEED); 44 45 /** 46 * The seed is reload periodically, there are two choice 47 * of seeds, default seed using the value from LFSR, or 48 * will use seed generated by ring oscillator. 49 */ 50 if (seed_sel == 1) 51 val |= RNG_RING_EN | RNG_SEED_SEL; 52 53 writel_relaxed(val, hrng->base + RNG_CTRL); 54 return 0; 55 } 56 57 static void hisi_rng_cleanup(struct hwrng *rng) 58 { 59 struct hisi_rng *hrng = to_hisi_rng(rng); 60 61 writel_relaxed(0, hrng->base + RNG_CTRL); 62 } 63 64 static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) 65 { 66 struct hisi_rng *hrng = to_hisi_rng(rng); 67 u32 *data = buf; 68 69 *data = readl_relaxed(hrng->base + RNG_RAN_NUM); 70 return 4; 71 } 72 73 static int hisi_rng_probe(struct platform_device *pdev) 74 { 75 struct hisi_rng *rng; 76 struct resource *res; 77 int ret; 78 79 rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); 80 if (!rng) 81 return -ENOMEM; 82 83 platform_set_drvdata(pdev, rng); 84 85 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 86 rng->base = devm_ioremap_resource(&pdev->dev, res); 87 if (IS_ERR(rng->base)) 88 return PTR_ERR(rng->base); 89 90 rng->rng.name = pdev->name; 91 rng->rng.init = hisi_rng_init; 92 rng->rng.cleanup = hisi_rng_cleanup; 93 rng->rng.read = hisi_rng_read; 94 95 ret = devm_hwrng_register(&pdev->dev, &rng->rng); 96 if (ret) { 97 dev_err(&pdev->dev, "failed to register hwrng\n"); 98 return ret; 99 } 100 101 return 0; 102 } 103 104 static const struct of_device_id hisi_rng_dt_ids[] = { 105 { .compatible = "hisilicon,hip04-rng" }, 106 { .compatible = "hisilicon,hip05-rng" }, 107 { } 108 }; 109 MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids); 110 111 static struct platform_driver hisi_rng_driver = { 112 .probe = hisi_rng_probe, 113 .driver = { 114 .name = "hisi-rng", 115 .of_match_table = of_match_ptr(hisi_rng_dt_ids), 116 }, 117 }; 118 119 module_platform_driver(hisi_rng_driver); 120 121 MODULE_LICENSE("GPL"); 122 MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>"); 123 MODULE_DESCRIPTION("Hisilicon random number generator driver"); 124