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/*
* Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/atomic.h>
#include <sys/syslog.h>
#include <sys/spinlock.h>
#include <dev/timer.h>
#define pr_trace(fmt, ...) kprintf("synch: " fmt, ##__VA_ARGS__)
#define pr_error(...) pr_trace(__VA_ARGS__)
/* XXX: Be very careful with this */
static struct spinlock __syslock;
/*
* Returns 0 on success, returns non-zero value
* on timeout/failure.
*/
int
spinlock_usleep(struct spinlock *lock, size_t usec_max)
{
struct timer tmr;
size_t usec_start, usec_cur;
size_t usec_elap;
int err;
if ((err = req_timer(TIMER_GP, &tmr)) != 0) {
pr_error("spinlock_usleep: req_timer() returned %d\n", err);
pr_error("spinlock_usleep: Failed to request timer...\n");
return err;
}
if (tmr.get_time_usec == NULL) {
pr_error("spinlock_usleep: Timer does not have get_time_usec()\n");
return -ENOTSUP;
}
usec_start = tmr.get_time_usec();
while (__atomic_test_and_set(&lock->lock, __ATOMIC_ACQUIRE)) {
usec_cur = tmr.get_time_usec();
usec_elap = (usec_cur - usec_start);
if (usec_elap > usec_max) {
return -1;
}
}
return 0;
}
void
spinlock_acquire(struct spinlock *lock)
{
while (__atomic_test_and_set(&lock->lock, __ATOMIC_ACQUIRE));
}
/*
* Lazy acquire a spinlock
*
* spinlock_try_acquire() may only spin one thread
* at a time, threads that want to spin too must
* explicity do it on their own.
*
* This function returns 1 (a value that may be
* spinned on) when the lock is acquired and a
* thread is already spinning on it.
*/
int
spinlock_try_acquire(struct spinlock *lock)
{
volatile int locked;
locked = atomic_load_int(&lock->lock);
if (locked != 0) {
return 1;
}
while (__atomic_test_and_set(&lock->lock, __ATOMIC_ACQUIRE));
return 0;
}
void
spinlock_release(struct spinlock *lock)
{
__atomic_clear(&lock->lock, __ATOMIC_RELEASE);
}
/*
* Attempt to hold the system-wide lock, returns 1
* if already held.
*
* XXX: Only use for CRITICAL code sections.
*/
int
syslock(void)
{
return spinlock_try_acquire(&__syslock);
}
/*
* Release the system-wide lock
*
* XXX: Only use for CRITICAL code sections.
*/
void
sysrel(void)
{
spinlock_release(&__syslock);
}
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