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