// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2016 HiSilicon Co., Ltd.
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*/
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/hw_random.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/random.h>
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#define RNG_SEED 0x0
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#define RNG_CTRL 0x4
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#define RNG_SEED_SEL BIT(2)
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#define RNG_RING_EN BIT(1)
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#define RNG_EN BIT(0)
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#define RNG_RAN_NUM 0x10
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#define RNG_PHY_SEED 0x14
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#define to_hisi_rng(p) container_of(p, struct hisi_rng, rng)
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static int seed_sel;
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module_param(seed_sel, int, S_IRUGO);
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MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
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struct hisi_rng {
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void __iomem *base;
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struct hwrng rng;
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};
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static int hisi_rng_init(struct hwrng *rng)
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{
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struct hisi_rng *hrng = to_hisi_rng(rng);
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int val = RNG_EN;
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u32 seed;
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/* get a random number as initial seed */
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get_random_bytes(&seed, sizeof(seed));
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writel_relaxed(seed, hrng->base + RNG_SEED);
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/**
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* The seed is reload periodically, there are two choice
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* of seeds, default seed using the value from LFSR, or
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* will use seed generated by ring oscillator.
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*/
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if (seed_sel == 1)
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val |= RNG_RING_EN | RNG_SEED_SEL;
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writel_relaxed(val, hrng->base + RNG_CTRL);
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return 0;
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}
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static void hisi_rng_cleanup(struct hwrng *rng)
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{
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struct hisi_rng *hrng = to_hisi_rng(rng);
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writel_relaxed(0, hrng->base + RNG_CTRL);
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}
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static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
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{
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struct hisi_rng *hrng = to_hisi_rng(rng);
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u32 *data = buf;
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*data = readl_relaxed(hrng->base + RNG_RAN_NUM);
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return 4;
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}
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static int hisi_rng_probe(struct platform_device *pdev)
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{
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struct hisi_rng *rng;
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int ret;
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rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
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if (!rng)
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return -ENOMEM;
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platform_set_drvdata(pdev, rng);
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rng->base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(rng->base))
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return PTR_ERR(rng->base);
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rng->rng.name = pdev->name;
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rng->rng.init = hisi_rng_init;
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rng->rng.cleanup = hisi_rng_cleanup;
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rng->rng.read = hisi_rng_read;
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ret = devm_hwrng_register(&pdev->dev, &rng->rng);
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if (ret) {
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dev_err(&pdev->dev, "failed to register hwrng\n");
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return ret;
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}
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return 0;
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}
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static const struct of_device_id hisi_rng_dt_ids[] __maybe_unused = {
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{ .compatible = "hisilicon,hip04-rng" },
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{ .compatible = "hisilicon,hip05-rng" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
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static struct platform_driver hisi_rng_driver = {
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.probe = hisi_rng_probe,
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.driver = {
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.name = "hisi-rng",
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.of_match_table = of_match_ptr(hisi_rng_dt_ids),
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},
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};
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module_platform_driver(hisi_rng_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
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MODULE_DESCRIPTION("Hisilicon random number generator driver");
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