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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2010-2012 Broadcom. All rights reserved.
* Copyright (c) 2013 Lubomir Rintel
*/
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/clk.h>
#define RNG_CTRL 0x0
#define RNG_STATUS 0x4
#define RNG_DATA 0x8
#define RNG_INT_MASK 0x10
/* enable rng */
#define RNG_RBGEN 0x1
/* the initial numbers generated are "less random" so will be discarded */
#define RNG_WARMUP_COUNT 0x40000
#define RNG_INT_OFF 0x1
struct bcm2835_rng_priv {
struct hwrng rng;
void __iomem *base;
bool mask_interrupts;
struct clk *clk;
};
static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng)
{
return container_of(rng, struct bcm2835_rng_priv, rng);
}
static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset)
{
/* MIPS chips strapped for BE will automagically configure the
* peripheral registers for CPU-native byte order.
*/
if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
return __raw_readl(priv->base + offset);
else
return readl(priv->base + offset);
}
static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val,
u32 offset)
{
if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
__raw_writel(val, priv->base + offset);
else
writel(val, priv->base + offset);
}
static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
bool wait)
{
struct bcm2835_rng_priv *priv = to_rng_priv(rng);
u32 max_words = max / sizeof(u32);
u32 num_words, count;
while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) {
if (!wait)
return 0;
cpu_relax();
}
num_words = rng_readl(priv, RNG_STATUS) >> 24;
if (num_words > max_words)
num_words = max_words;
for (count = 0; count < num_words; count++)
((u32 *)buf)[count] = rng_readl(priv, RNG_DATA);
return num_words * sizeof(u32);
}
static int bcm2835_rng_init(struct hwrng *rng)
{
struct bcm2835_rng_priv *priv = to_rng_priv(rng);
int ret = 0;
u32 val;
if (!IS_ERR(priv->clk)) {
ret = clk_prepare_enable(priv->clk);
if (ret)
return ret;
}
if (priv->mask_interrupts) {
/* mask the interrupt */
val = rng_readl(priv, RNG_INT_MASK);
val |= RNG_INT_OFF;
rng_writel(priv, val, RNG_INT_MASK);
}
/* set warm-up count & enable */
rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS);
rng_writel(priv, RNG_RBGEN, RNG_CTRL);
return ret;
}
static void bcm2835_rng_cleanup(struct hwrng *rng)
{
struct bcm2835_rng_priv *priv = to_rng_priv(rng);
/* disable rng hardware */
rng_writel(priv, 0, RNG_CTRL);
if (!IS_ERR(priv->clk))
clk_disable_unprepare(priv->clk);
}
struct bcm2835_rng_of_data {
bool mask_interrupts;
};
static const struct bcm2835_rng_of_data nsp_rng_of_data = {
.mask_interrupts = true,
};
static const struct of_device_id bcm2835_rng_of_match[] = {
{ .compatible = "brcm,bcm2835-rng"},
{ .compatible = "brcm,bcm-nsp-rng", .data = &nsp_rng_of_data },
{ .compatible = "brcm,bcm5301x-rng", .data = &nsp_rng_of_data },
{ .compatible = "brcm,bcm6368-rng"},
{},
};
static int bcm2835_rng_probe(struct platform_device *pdev)
{
const struct bcm2835_rng_of_data *of_data;
struct device *dev = &pdev->dev;
const struct of_device_id *rng_id;
struct bcm2835_rng_priv *priv;
int err;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
platform_set_drvdata(pdev, priv);
/* map peripheral */
priv->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
/* Clock is optional on most platforms */
priv->clk = devm_clk_get(dev, NULL);
if (PTR_ERR(priv->clk) == -EPROBE_DEFER)
return -EPROBE_DEFER;
priv->rng.name = pdev->name;
priv->rng.init = bcm2835_rng_init;
priv->rng.read = bcm2835_rng_read;
priv->rng.cleanup = bcm2835_rng_cleanup;
if (dev_of_node(dev)) {
rng_id = of_match_node(bcm2835_rng_of_match, dev->of_node);
if (!rng_id)
return -EINVAL;
/* Check for rng init function, execute it */
of_data = rng_id->data;
if (of_data)
priv->mask_interrupts = of_data->mask_interrupts;
}
/* register driver */
err = devm_hwrng_register(dev, &priv->rng);
if (err)
dev_err(dev, "hwrng registration failed\n");
else
dev_info(dev, "hwrng registered\n");
return err;
}
MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);
static const struct platform_device_id bcm2835_rng_devtype[] = {
{ .name = "bcm2835-rng" },
{ .name = "bcm63xx-rng" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, bcm2835_rng_devtype);
static struct platform_driver bcm2835_rng_driver = {
.driver = {
.name = "bcm2835-rng",
.of_match_table = bcm2835_rng_of_match,
},
.probe = bcm2835_rng_probe,
.id_table = bcm2835_rng_devtype,
};
module_platform_driver(bcm2835_rng_driver);
MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver");
MODULE_LICENSE("GPL v2");
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