LXR linux/drivers/char/hw_random/hisi-rng.c

   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
  28static int seed_sel;
  29module_param(seed_sel, int, S_IRUGO);
  30MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
  31
  32struct hisi_rng {
  33        void __iomem *base;
  34        struct hwrng rng;
  35};
  36
  37static 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
  60static 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
  67static 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
  76static 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
 107static const struct of_device_id hisi_rng_dt_ids[] = {
 108        { .compatible = "hisilicon,hip04-rng" },
 109        { .compatible = "hisilicon,hip05-rng" },
 110        { }
 111};
 112MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
 113
 114static 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
 122module_platform_driver(hisi_rng_driver);
 123
 124MODULE_LICENSE("GPL");
 125MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
 126MODULE_DESCRIPTION("Hisilicon random number generator driver");
 127