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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2019 HiSilicon Limited. */
#include <linux/acpi.h>
#include <linux/err.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/random.h>
#define HISI_TRNG_REG 0x00F0
#define HISI_TRNG_BYTES 4
#define HISI_TRNG_QUALITY 512
#define SLEEP_US 10
#define TIMEOUT_US 10000
struct hisi_trng {
void __iomem *base;
struct hwrng rng;
};
static int hisi_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
struct hisi_trng *trng;
int currsize = 0;
u32 val = 0;
u32 ret;
trng = container_of(rng, struct hisi_trng, rng);
do {
ret = readl_poll_timeout(trng->base + HISI_TRNG_REG, val,
val, SLEEP_US, TIMEOUT_US);
if (ret)
return currsize;
if (max - currsize >= HISI_TRNG_BYTES) {
memcpy(buf + currsize, &val, HISI_TRNG_BYTES);
currsize += HISI_TRNG_BYTES;
if (currsize == max)
return currsize;
continue;
}
/* copy remaining bytes */
memcpy(buf + currsize, &val, max - currsize);
currsize = max;
} while (currsize < max);
return currsize;
}
static int hisi_trng_probe(struct platform_device *pdev)
{
struct hisi_trng *trng;
int ret;
trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
if (!trng)
return -ENOMEM;
trng->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(trng->base))
return PTR_ERR(trng->base);
trng->rng.name = pdev->name;
trng->rng.read = hisi_trng_read;
trng->rng.quality = HISI_TRNG_QUALITY;
ret = devm_hwrng_register(&pdev->dev, &trng->rng);
if (ret)
dev_err(&pdev->dev, "failed to register hwrng!\n");
return ret;
}
static const struct acpi_device_id hisi_trng_acpi_match[] = {
{ "HISI02B3", 0 },
{ }
};
MODULE_DEVICE_TABLE(acpi, hisi_trng_acpi_match);
static struct platform_driver hisi_trng_driver = {
.probe = hisi_trng_probe,
.driver = {
.name = "hisi-trng-v2",
.acpi_match_table = ACPI_PTR(hisi_trng_acpi_match),
},
};
module_platform_driver(hisi_trng_driver);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Weili Qian <qianweili@huawei.com>");
MODULE_AUTHOR("Zaibo Xu <xuzaibo@huawei.com>");
MODULE_DESCRIPTION("HiSilicon true random number generator V2 driver");
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