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/**
* Copyright (c) 2010-2012 Broadcom. All rights reserved.
* Copyright (c) 2013 Lubomir Rintel
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License ("GPL")
* version 2, as published by the Free Software Foundation.
*/
#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>
#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;
};
static void __init nsp_rng_init(void __iomem *base)
{
u32 val;
/* mask the interrupt */
val = readl(base + RNG_INT_MASK);
val |= RNG_INT_OFF;
writel(val, base + RNG_INT_MASK);
}
static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng)
{
return container_of(rng, struct bcm2835_rng_priv, rng);
}
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 ((__raw_readl(priv->base + RNG_STATUS) >> 24) == 0) {
if (!wait)
return 0;
cpu_relax();
}
num_words = readl(priv->base + RNG_STATUS) >> 24;
if (num_words > max_words)
num_words = max_words;
for (count = 0; count < num_words; count++)
((u32 *)buf)[count] = readl(priv->base + RNG_DATA);
return num_words * sizeof(u32);
}
static int bcm2835_rng_init(struct hwrng *rng)
{
struct bcm2835_rng_priv *priv = to_rng_priv(rng);
/* set warm-up count & enable */
__raw_writel(RNG_WARMUP_COUNT, priv->base + RNG_STATUS);
__raw_writel(RNG_RBGEN, priv->base + RNG_CTRL);
return 0;
}
static const struct of_device_id bcm2835_rng_of_match[] = {
{ .compatible = "brcm,bcm2835-rng"},
{ .compatible = "brcm,bcm-nsp-rng", .data = nsp_rng_init},
{ .compatible = "brcm,bcm5301x-rng", .data = nsp_rng_init},
{},
};
static int bcm2835_rng_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
void (*rng_setup)(void __iomem *base);
const struct of_device_id *rng_id;
struct bcm2835_rng_priv *priv;
struct resource *r;
int err;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
platform_set_drvdata(pdev, priv);
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
/* map peripheral */
priv->base = devm_ioremap_resource(dev, r);
if (IS_ERR(priv->base)) {
dev_err(dev, "failed to remap rng regs");
return PTR_ERR(priv->base);
}
priv->rng.name = "bcm2835-rng";
priv->rng.init = bcm2835_rng_init;
priv->rng.read = bcm2835_rng_read;
rng_id = of_match_node(bcm2835_rng_of_match, np);
if (!rng_id)
return -EINVAL;
/* Check for rng init function, execute it */
rng_setup = rng_id->data;
if (rng_setup)
rng_setup(priv->base);
/* register driver */
err = hwrng_register(&priv->rng);
if (err)
dev_err(dev, "hwrng registration failed\n");
else
dev_info(dev, "hwrng registered\n");
return err;
}
static int bcm2835_rng_remove(struct platform_device *pdev)
{
struct bcm2835_rng_priv *priv = platform_get_drvdata(pdev);
/* disable rng hardware */
__raw_writel(0, priv->base + RNG_CTRL);
/* unregister driver */
hwrng_unregister(&priv->rng);
return 0;
}
MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);
static struct platform_driver bcm2835_rng_driver = {
.driver = {
.name = "bcm2835-rng",
.of_match_table = bcm2835_rng_of_match,
},
.probe = bcm2835_rng_probe,
.remove = bcm2835_rng_remove,
};
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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