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 int ret; 77 78 rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); 79 if (!rng) 80 return -ENOMEM; 81 82 rng->base = devm_platform_ioremap_resource(pdev, 0); 83 if (IS_ERR(rng->base)) 84 return PTR_ERR(rng->base); 85 86 rng->rng.name = pdev->name; 87 rng->rng.init = hisi_rng_init; 88 rng->rng.cleanup = hisi_rng_cleanup; 89 rng->rng.read = hisi_rng_read; 90 91 ret = devm_hwrng_register(&pdev->dev, &rng->rng); 92 if (ret) 93 return dev_err_probe(&pdev->dev, ret, "failed to register hwrng\n"); 94 95 return 0; 96 } 97 98 static const struct of_device_id hisi_rng_dt_ids[] __maybe_unused = { 99 { .compatible = "hisilicon,hip04-rng" }, 100 { .compatible = "hisilicon,hip05-rng" }, 101 { } 102 }; 103 MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids); 104 105 static struct platform_driver hisi_rng_driver = { 106 .probe = hisi_rng_probe, 107 .driver = { 108 .name = "hisi-rng", 109 .of_match_table = of_match_ptr(hisi_rng_dt_ids), 110 }, 111 }; 112 113 module_platform_driver(hisi_rng_driver); 114 115 MODULE_LICENSE("GPL"); 116 MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>"); 117 MODULE_DESCRIPTION("Hisilicon random number generator driver"); 118