1 /* 2 * Copyright (C) 2016 HiSilicon Co., Ltd. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9 #include <linux/err.h> 10 #include <linux/kernel.h> 11 #include <linux/hw_random.h> 12 #include <linux/io.h> 13 #include <linux/module.h> 14 #include <linux/of.h> 15 #include <linux/platform_device.h> 16 #include <linux/random.h> 17 18 #define RNG_SEED 0x0 19 #define RNG_CTRL 0x4 20 #define RNG_SEED_SEL BIT(2) 21 #define RNG_RING_EN BIT(1) 22 #define RNG_EN BIT(0) 23 #define RNG_RAN_NUM 0x10 24 #define RNG_PHY_SEED 0x14 25 26 #define to_hisi_rng(p) container_of(p, struct hisi_rng, rng) 27 28 static int seed_sel; 29 module_param(seed_sel, int, S_IRUGO); 30 MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator."); 31 32 struct hisi_rng { 33 void __iomem *base; 34 struct hwrng rng; 35 }; 36 37 static int hisi_rng_init(struct hwrng *rng) 38 { 39 struct hisi_rng *hrng = to_hisi_rng(rng); 40 int val = RNG_EN; 41 u32 seed; 42 43 /* get a random number as initial seed */ 44 get_random_bytes(&seed, sizeof(seed)); 45 46 writel_relaxed(seed, hrng->base + RNG_SEED); 47 48 /** 49 * The seed is reload periodically, there are two choice 50 * of seeds, default seed using the value from LFSR, or 51 * will use seed generated by ring oscillator. 52 */ 53 if (seed_sel == 1) 54 val |= RNG_RING_EN | RNG_SEED_SEL; 55 56 writel_relaxed(val, hrng->base + RNG_CTRL); 57 return 0; 58 } 59 60 static void hisi_rng_cleanup(struct hwrng *rng) 61 { 62 struct hisi_rng *hrng = to_hisi_rng(rng); 63 64 writel_relaxed(0, hrng->base + RNG_CTRL); 65 } 66 67 static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) 68 { 69 struct hisi_rng *hrng = to_hisi_rng(rng); 70 u32 *data = buf; 71 72 *data = readl_relaxed(hrng->base + RNG_RAN_NUM); 73 return 4; 74 } 75 76 static int hisi_rng_probe(struct platform_device *pdev) 77 { 78 struct hisi_rng *rng; 79 struct resource *res; 80 int ret; 81 82 rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); 83 if (!rng) 84 return -ENOMEM; 85 86 platform_set_drvdata(pdev, rng); 87 88 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 89 rng->base = devm_ioremap_resource(&pdev->dev, res); 90 if (IS_ERR(rng->base)) 91 return PTR_ERR(rng->base); 92 93 rng->rng.name = pdev->name; 94 rng->rng.init = hisi_rng_init; 95 rng->rng.cleanup = hisi_rng_cleanup; 96 rng->rng.read = hisi_rng_read; 97 98 ret = devm_hwrng_register(&pdev->dev, &rng->rng); 99 if (ret) { 100 dev_err(&pdev->dev, "failed to register hwrng\n"); 101 return ret; 102 } 103 104 return 0; 105 } 106 107 static const struct of_device_id hisi_rng_dt_ids[] = { 108 { .compatible = "hisilicon,hip04-rng" }, 109 { .compatible = "hisilicon,hip05-rng" }, 110 { } 111 }; 112 MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids); 113 114 static struct platform_driver hisi_rng_driver = { 115 .probe = hisi_rng_probe, 116 .driver = { 117 .name = "hisi-rng", 118 .of_match_table = of_match_ptr(hisi_rng_dt_ids), 119 }, 120 }; 121 122 module_platform_driver(hisi_rng_driver); 123 124 MODULE_LICENSE("GPL"); 125 MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>"); 126 MODULE_DESCRIPTION("Hisilicon random number generator driver"); 127