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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 | // SPDX-License-Identifier: GPL-2.0-only /* * PIC32 RNG driver * * Joshua Henderson <joshua.henderson@microchip.com> * Copyright (C) 2016 Microchip Technology Inc. All rights reserved. */ #include <linux/clk.h> #include <linux/clkdev.h> #include <linux/err.h> #include <linux/hw_random.h> #include <linux/io.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of.h> #include <linux/of_device.h> #include <linux/platform_device.h> #include <linux/slab.h> #define RNGCON 0x04 #define TRNGEN BIT(8) #define PRNGEN BIT(9) #define PRNGCONT BIT(10) #define TRNGMOD BIT(11) #define SEEDLOAD BIT(12) #define RNGPOLY1 0x08 #define RNGPOLY2 0x0C #define RNGNUMGEN1 0x10 #define RNGNUMGEN2 0x14 #define RNGSEED1 0x18 #define RNGSEED2 0x1C #define RNGRCNT 0x20 #define RCNT_MASK 0x7F struct pic32_rng { void __iomem *base; struct hwrng rng; }; /* * The TRNG can generate up to 24Mbps. This is a timeout that should be safe * enough given the instructions in the loop and that the TRNG may not always * be at maximum rate. */ #define RNG_TIMEOUT 500 static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) { struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng); u64 *data = buf; u32 t; unsigned int timeout = RNG_TIMEOUT; do { t = readl(priv->base + RNGRCNT) & RCNT_MASK; if (t == 64) { /* TRNG value comes through the seed registers */ *data = ((u64)readl(priv->base + RNGSEED2) << 32) + readl(priv->base + RNGSEED1); return 8; } } while (wait && --timeout); return -EIO; } static int pic32_rng_probe(struct platform_device *pdev) { struct pic32_rng *priv; struct clk *clk; u32 v; int ret; priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); if (!priv) return -ENOMEM; priv->base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(priv->base)) return PTR_ERR(priv->base); clk = devm_clk_get_enabled(&pdev->dev, NULL); if (IS_ERR(clk)) return PTR_ERR(clk); /* enable TRNG in enhanced mode */ v = TRNGEN | TRNGMOD; writel(v, priv->base + RNGCON); priv->rng.name = pdev->name; priv->rng.read = pic32_rng_read; ret = devm_hwrng_register(&pdev->dev, &priv->rng); if (ret) return ret; platform_set_drvdata(pdev, priv); return 0; } static int pic32_rng_remove(struct platform_device *pdev) { struct pic32_rng *rng = platform_get_drvdata(pdev); writel(0, rng->base + RNGCON); return 0; } static const struct of_device_id pic32_rng_of_match[] __maybe_unused = { { .compatible = "microchip,pic32mzda-rng", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, pic32_rng_of_match); static struct platform_driver pic32_rng_driver = { .probe = pic32_rng_probe, .remove = pic32_rng_remove, .driver = { .name = "pic32-rng", .of_match_table = of_match_ptr(pic32_rng_of_match), }, }; module_platform_driver(pic32_rng_driver); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>"); MODULE_DESCRIPTION("Microchip PIC32 RNG Driver"); |