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// SPDX-License-Identifier: GPL-2.0
/*
* Ingenic Random Number Generator driver
* Copyright (c) 2017 PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
* Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
*/
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
/* RNG register offsets */
#define RNG_REG_ERNG_OFFSET 0x0
#define RNG_REG_RNG_OFFSET 0x4
/* bits within the ERND register */
#define ERNG_READY BIT(31)
#define ERNG_ENABLE BIT(0)
enum ingenic_rng_version {
ID_JZ4780,
ID_X1000,
};
/* Device associated memory */
struct ingenic_rng {
enum ingenic_rng_version version;
void __iomem *base;
struct hwrng rng;
};
static int ingenic_rng_init(struct hwrng *rng)
{
struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
writel(ERNG_ENABLE, priv->base + RNG_REG_ERNG_OFFSET);
return 0;
}
static void ingenic_rng_cleanup(struct hwrng *rng)
{
struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
writel(0, priv->base + RNG_REG_ERNG_OFFSET);
}
static int ingenic_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
u32 *data = buf;
u32 status;
int ret;
if (priv->version >= ID_X1000) {
ret = readl_poll_timeout(priv->base + RNG_REG_ERNG_OFFSET, status,
status & ERNG_READY, 10, 1000);
if (ret == -ETIMEDOUT) {
pr_err("%s: Wait for RNG data ready timeout\n", __func__);
return ret;
}
} else {
/*
* A delay is required so that the current RNG data is not bit shifted
* version of previous RNG data which could happen if random data is
* read continuously from this device.
*/
udelay(20);
}
*data = readl(priv->base + RNG_REG_RNG_OFFSET);
return 4;
}
static int ingenic_rng_probe(struct platform_device *pdev)
{
struct ingenic_rng *priv;
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)) {
pr_err("%s: Failed to map RNG registers\n", __func__);
return PTR_ERR(priv->base);
}
priv->version = (enum ingenic_rng_version)of_device_get_match_data(&pdev->dev);
priv->rng.name = pdev->name;
priv->rng.init = ingenic_rng_init;
priv->rng.cleanup = ingenic_rng_cleanup;
priv->rng.read = ingenic_rng_read;
ret = hwrng_register(&priv->rng);
if (ret) {
dev_err(&pdev->dev, "Failed to register hwrng\n");
return ret;
}
platform_set_drvdata(pdev, priv);
dev_info(&pdev->dev, "Ingenic RNG driver registered\n");
return 0;
}
static int ingenic_rng_remove(struct platform_device *pdev)
{
struct ingenic_rng *priv = platform_get_drvdata(pdev);
hwrng_unregister(&priv->rng);
writel(0, priv->base + RNG_REG_ERNG_OFFSET);
return 0;
}
static const struct of_device_id ingenic_rng_of_match[] = {
{ .compatible = "ingenic,jz4780-rng", .data = (void *) ID_JZ4780 },
{ .compatible = "ingenic,x1000-rng", .data = (void *) ID_X1000 },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, ingenic_rng_of_match);
static struct platform_driver ingenic_rng_driver = {
.probe = ingenic_rng_probe,
.remove = ingenic_rng_remove,
.driver = {
.name = "ingenic-rng",
.of_match_table = ingenic_rng_of_match,
},
};
module_platform_driver(ingenic_rng_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>");
MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
MODULE_DESCRIPTION("Ingenic Random Number Generator driver");
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