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/* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
/* Much of this ripped from drivers/char/hw_random.c, see there for other
* copyright.
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*/
#include <linux/sched/signal.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/miscdevice.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <init.h>
#include <irq_kern.h>
#include <os.h>
/*
* core module information
*/
#define RNG_MODULE_NAME "hw_random"
/* Changed at init time, in the non-modular case, and at module load
* time, in the module case. Presumably, the module subsystem
* protects against a module being loaded twice at the same time.
*/
static int random_fd = -1;
static struct hwrng hwrng;
static DECLARE_COMPLETION(have_data);
static int rng_dev_read(struct hwrng *rng, void *buf, size_t max, bool block)
{
int ret;
for (;;) {
ret = os_read_file(random_fd, buf, max);
if (block && ret == -EAGAIN) {
add_sigio_fd(random_fd);
ret = wait_for_completion_killable(&have_data);
ignore_sigio_fd(random_fd);
deactivate_fd(random_fd, RANDOM_IRQ);
if (ret < 0)
break;
} else {
break;
}
}
return ret != -EAGAIN ? ret : 0;
}
static irqreturn_t random_interrupt(int irq, void *data)
{
complete(&have_data);
return IRQ_HANDLED;
}
/*
* rng_init - initialize RNG module
*/
static int __init rng_init (void)
{
int err;
err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
if (err < 0)
goto out;
random_fd = err;
err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
0, "random", NULL);
if (err < 0)
goto err_out_cleanup_hw;
sigio_broken(random_fd);
hwrng.name = RNG_MODULE_NAME;
hwrng.read = rng_dev_read;
hwrng.quality = 1024;
err = hwrng_register(&hwrng);
if (err) {
pr_err(RNG_MODULE_NAME " registering failed (%d)\n", err);
goto err_out_cleanup_hw;
}
out:
return err;
err_out_cleanup_hw:
os_close_file(random_fd);
random_fd = -1;
goto out;
}
/*
* rng_cleanup - shutdown RNG module
*/
static void cleanup(void)
{
free_irq_by_fd(random_fd);
os_close_file(random_fd);
}
static void __exit rng_cleanup(void)
{
hwrng_unregister(&hwrng);
os_close_file(random_fd);
}
module_init (rng_init);
module_exit (rng_cleanup);
__uml_exitcall(cleanup);
MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
MODULE_LICENSE("GPL");
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