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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* PPS dummy generator
*
* Copyright (C) 2024 Rodolfo Giometti <giometti@enneenne.com>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/timer.h>
#include <linux/random.h>
#include <linux/pps_gen_kernel.h>
static struct pps_gen_device *pps_gen;
static struct timer_list ktimer;
static unsigned int get_random_delay(void)
{
unsigned int delay = get_random_u8() & 0x0f;
return (delay + 1) * HZ;
}
/*
* The kernel timer
*/
static void pps_gen_ktimer_event(struct timer_list *unused)
{
pps_gen_event(pps_gen, PPS_GEN_EVENT_MISSEDPULSE, NULL);
}
/*
* PPS Generator methods
*/
static int pps_gen_dummy_get_time(struct pps_gen_device *pps_gen,
struct timespec64 *time)
{
struct system_time_snapshot snap;
ktime_get_snapshot(&snap);
*time = ktime_to_timespec64(snap.real);
return 0;
}
static int pps_gen_dummy_enable(struct pps_gen_device *pps_gen, bool enable)
{
if (enable)
mod_timer(&ktimer, jiffies + get_random_delay());
else
timer_delete_sync(&ktimer);
return 0;
}
/*
* The PPS info struct
*/
static const struct pps_gen_source_info pps_gen_dummy_info = {
.use_system_clock = true,
.get_time = pps_gen_dummy_get_time,
.enable = pps_gen_dummy_enable,
};
/*
* Module staff
*/
static void __exit pps_gen_dummy_exit(void)
{
timer_delete_sync(&ktimer);
pps_gen_unregister_source(pps_gen);
}
static int __init pps_gen_dummy_init(void)
{
pps_gen = pps_gen_register_source(&pps_gen_dummy_info);
if (IS_ERR(pps_gen))
return PTR_ERR(pps_gen);
timer_setup(&ktimer, pps_gen_ktimer_event, 0);
return 0;
}
module_init(pps_gen_dummy_init);
module_exit(pps_gen_dummy_exit);
MODULE_AUTHOR("Rodolfo Giometti <giometti@enneenne.com>");
MODULE_DESCRIPTION("LinuxPPS dummy generator");
MODULE_LICENSE("GPL");
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