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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/random.h>
#include <linux/hw_random.h>
static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
unsigned long *buf;
int i, len;
/* We rely on rng_buffer_size() being >= sizeof(unsigned long) */
len = max / sizeof(unsigned long);
buf = (unsigned long *)data;
for (i = 0; i < len; i++)
powernv_get_random_long(buf++);
return len * sizeof(unsigned long);
}
static struct hwrng powernv_hwrng = {
.name = "powernv-rng",
.read = powernv_rng_read,
};
static int powernv_rng_remove(struct platform_device *pdev)
{
hwrng_unregister(&powernv_hwrng);
return 0;
}
static int powernv_rng_probe(struct platform_device *pdev)
{
int rc;
rc = hwrng_register(&powernv_hwrng);
if (rc) {
/* We only register one device, ignore any others */
if (rc == -EEXIST)
rc = -ENODEV;
return rc;
}
pr_info("Registered powernv hwrng.\n");
return 0;
}
static const struct of_device_id powernv_rng_match[] = {
{ .compatible = "ibm,power-rng",},
{},
};
MODULE_DEVICE_TABLE(of, powernv_rng_match);
static struct platform_driver powernv_rng_driver = {
.driver = {
.name = "powernv_rng",
.of_match_table = powernv_rng_match,
},
.probe = powernv_rng_probe,
.remove = powernv_rng_remove,
};
module_platform_driver(powernv_rng_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above");
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