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/*
* Copyright (c) 2016 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* derived from Linux kernel drivers/char/hw_random/core.c
*/
#include <common.h>
#include <linux/hw_random.h>
#include <malloc.h>
static LIST_HEAD(hwrngs);
#define RNG_BUFFER_SIZE 32
int hwrng_get_data(struct hwrng *rng, void *buffer, size_t size, int wait)
{
return rng->read(rng, buffer, size, wait);
}
static int hwrng_init(struct hwrng *rng)
{
int ret = 0;
if (rng->init)
ret = rng->init(rng);
if (!ret)
list_add_tail(&rng->list, &hwrngs);
return ret;
}
static ssize_t rng_dev_read(struct cdev *cdev, void *buf, size_t size,
loff_t offset, unsigned long flags)
{
struct hwrng *rng = container_of(cdev, struct hwrng, cdev);
size_t count = size;
ssize_t cur = 0;
int len;
memset(buf, 0, size);
while (count) {
int max = min(count, (size_t)RNG_BUFFER_SIZE);
len = hwrng_get_data(rng, rng->buf, max, true);
if (len < 0) {
cur = len;
break;
}
memcpy(buf + cur, rng->buf, len);
count -= len;
cur += len;
}
return cur;
}
static struct cdev_operations rng_chrdev_ops = {
.read = rng_dev_read,
};
static int hwrng_register_cdev(struct hwrng *rng)
{
struct device_d *dev = rng->dev;
const char *alias;
char *devname;
int err;
alias = of_alias_get(dev->device_node);
if (alias) {
devname = xstrdup(alias);
} else {
err = cdev_find_free_index("hwrng");
if (err < 0) {
dev_err(dev, "no index found to name device\n");
return err;
}
devname = xasprintf("hwrng%d", err);
}
rng->cdev.name = devname;
rng->cdev.flags = DEVFS_IS_CHARACTER_DEV;
rng->cdev.ops = &rng_chrdev_ops;
rng->cdev.dev = rng->dev;
return devfs_create(&rng->cdev);
}
static void hwrng_unregister_cdev(struct hwrng *rng)
{
devfs_remove(&rng->cdev);
free(rng->cdev.name);
}
struct hwrng *hwrng_get_first(void)
{
if (list_empty(&hwrngs))
return ERR_PTR(-ENODEV);
else
return list_first_entry(&hwrngs, struct hwrng, list);
}
int hwrng_register(struct device_d *dev, struct hwrng *rng)
{
int err;
if (rng->name == NULL || rng->read == NULL)
return -EINVAL;
rng->buf = xzalloc(RNG_BUFFER_SIZE);
rng->dev = dev;
err = hwrng_init(rng);
if (err) {
free(rng->buf);
return err;
}
err = hwrng_register_cdev(rng);
if (err)
free(rng->buf);
return err;
}
void hwrng_unregister(struct hwrng *rng)
{
hwrng_unregister_cdev(rng);
free(rng->buf);
}
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