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/*
* Driver for Mediatek Hardware Random Number Generator
*
* Copyright (C) 2017 Sean Wang <sean.wang@mediatek.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define MTK_RNG_DEV KBUILD_MODNAME
#include <linux/clk.h>
#include <linux/delay.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/of.h>
#include <linux/platform_device.h>
#define USEC_POLL 2
#define TIMEOUT_POLL 20
#define RNG_CTRL 0x00
#define RNG_EN BIT(0)
#define RNG_READY BIT(31)
#define RNG_DATA 0x08
#define to_mtk_rng(p) container_of(p, struct mtk_rng, rng)
struct mtk_rng {
void __iomem *base;
struct clk *clk;
struct hwrng rng;
};
static int mtk_rng_init(struct hwrng *rng)
{
struct mtk_rng *priv = to_mtk_rng(rng);
u32 val;
int err;
err = clk_prepare_enable(priv->clk);
if (err)
return err;
val = readl(priv->base + RNG_CTRL);
val |= RNG_EN;
writel(val, priv->base + RNG_CTRL);
return 0;
}
static void mtk_rng_cleanup(struct hwrng *rng)
{
struct mtk_rng *priv = to_mtk_rng(rng);
u32 val;
val = readl(priv->base + RNG_CTRL);
val &= ~RNG_EN;
writel(val, priv->base + RNG_CTRL);
clk_disable_unprepare(priv->clk);
}
static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait)
{
struct mtk_rng *priv = to_mtk_rng(rng);
int ready;
ready = readl(priv->base + RNG_CTRL) & RNG_READY;
if (!ready && wait)
readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready,
ready & RNG_READY, USEC_POLL,
TIMEOUT_POLL);
return !!ready;
}
static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
struct mtk_rng *priv = to_mtk_rng(rng);
int retval = 0;
while (max >= sizeof(u32)) {
if (!mtk_rng_wait_ready(rng, wait))
break;
*(u32 *)buf = readl(priv->base + RNG_DATA);
retval += sizeof(u32);
buf += sizeof(u32);
max -= sizeof(u32);
}
return retval || !wait ? retval : -EIO;
}
static int mtk_rng_probe(struct platform_device *pdev)
{
struct resource *res;
int ret;
struct mtk_rng *priv;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "no iomem resource\n");
return -ENXIO;
}
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->rng.name = pdev->name;
priv->rng.init = mtk_rng_init;
priv->rng.cleanup = mtk_rng_cleanup;
priv->rng.read = mtk_rng_read;
priv->clk = devm_clk_get(&pdev->dev, "rng");
if (IS_ERR(priv->clk)) {
ret = PTR_ERR(priv->clk);
dev_err(&pdev->dev, "no clock for device: %d\n", ret);
return ret;
}
priv->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
ret = devm_hwrng_register(&pdev->dev, &priv->rng);
if (ret) {
dev_err(&pdev->dev, "failed to register rng device: %d\n",
ret);
return ret;
}
dev_info(&pdev->dev, "registered RNG driver\n");
return 0;
}
static const struct of_device_id mtk_rng_match[] = {
{ .compatible = "mediatek,mt7623-rng" },
{},
};
MODULE_DEVICE_TABLE(of, mtk_rng_match);
static struct platform_driver mtk_rng_driver = {
.probe = mtk_rng_probe,
.driver = {
.name = MTK_RNG_DEV,
.of_match_table = mtk_rng_match,
},
};
module_platform_driver(mtk_rng_driver);
MODULE_DESCRIPTION("Mediatek Random Number Generator Driver");
MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
MODULE_LICENSE("GPL");
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