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// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
* Copyright (c) 2016 BayLibre, SAS.
* Author: Neil Armstrong <narmstrong@baylibre.com>
* Copyright (C) 2014 Amlogic, Inc.
*/
#include <linux/err.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/of.h>
#include <linux/clk.h>
#include <linux/iopoll.h>
#define RNG_DATA 0x00
#define RNG_S4_DATA 0x08
#define RNG_S4_CFG 0x00
#define RUN_BIT BIT(0)
#define SEED_READY_STS_BIT BIT(31)
struct meson_rng_priv {
int (*read)(struct hwrng *rng, void *buf, size_t max, bool wait);
};
struct meson_rng_data {
void __iomem *base;
struct hwrng rng;
struct device *dev;
};
static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
struct meson_rng_data *data =
container_of(rng, struct meson_rng_data, rng);
*(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
return sizeof(u32);
}
static int meson_rng_wait_status(void __iomem *cfg_addr, int bit)
{
u32 status = 0;
int ret;
ret = readl_relaxed_poll_timeout_atomic(cfg_addr,
status, !(status & bit),
10, 10000);
if (ret)
return -EBUSY;
return 0;
}
static int meson_s4_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
struct meson_rng_data *data =
container_of(rng, struct meson_rng_data, rng);
void __iomem *cfg_addr = data->base + RNG_S4_CFG;
int err;
writel_relaxed(readl_relaxed(cfg_addr) | SEED_READY_STS_BIT, cfg_addr);
err = meson_rng_wait_status(cfg_addr, SEED_READY_STS_BIT);
if (err) {
dev_err(data->dev, "Seed isn't ready, try again\n");
return err;
}
err = meson_rng_wait_status(cfg_addr, RUN_BIT);
if (err) {
dev_err(data->dev, "Can't get random number, try again\n");
return err;
}
*(u32 *)buf = readl_relaxed(data->base + RNG_S4_DATA);
return sizeof(u32);
}
static int meson_rng_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct meson_rng_data *data;
struct clk *core_clk;
const struct meson_rng_priv *priv;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
priv = device_get_match_data(&pdev->dev);
if (!priv)
return -ENODEV;
data->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(data->base))
return PTR_ERR(data->base);
core_clk = devm_clk_get_optional_enabled(dev, "core");
if (IS_ERR(core_clk))
return dev_err_probe(dev, PTR_ERR(core_clk),
"Failed to get core clock\n");
data->rng.name = pdev->name;
data->rng.read = priv->read;
data->dev = &pdev->dev;
return devm_hwrng_register(dev, &data->rng);
}
static const struct meson_rng_priv meson_rng_priv = {
.read = meson_rng_read,
};
static const struct meson_rng_priv meson_rng_priv_s4 = {
.read = meson_s4_rng_read,
};
static const struct of_device_id meson_rng_of_match[] = {
{
.compatible = "amlogic,meson-rng",
.data = (void *)&meson_rng_priv,
},
{
.compatible = "amlogic,meson-s4-rng",
.data = (void *)&meson_rng_priv_s4,
},
{},
};
MODULE_DEVICE_TABLE(of, meson_rng_of_match);
static struct platform_driver meson_rng_driver = {
.probe = meson_rng_probe,
.driver = {
.name = "meson-rng",
.of_match_table = meson_rng_of_match,
},
};
module_platform_driver(meson_rng_driver);
MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
MODULE_LICENSE("Dual BSD/GPL");
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