/*
 * remote_spinlock.c - kernel remote spinlock implementation.
 *
 * Authors   Alain   Greiner (2016,2017,2018)
 *
 * Copyright (c) UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-MKH.
 *
 * ALMOS-MKH is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-MKH is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <hal_kernel_types.h>
#include <hal_remote.h>
#include <hal_irqmask.h>
#include <thread.h>
#include <cluster.h>
#include <scheduler.h>
#include <remote_spinlock.h>

///////////////////////////////////////////
void remote_spinlock_init( xptr_t lock_xp )
{
	remote_spinlock_t * ptr = GET_PTR( lock_xp );
	cxy_t               cxy = GET_CXY( lock_xp );

	hal_remote_sw ( XPTR( cxy , &ptr->taken ) , 0 );

#if DEBUG_REMOTE_SPINLOCKS
hal_remote_swd( XPTR( cxy , &ptr->owner ) , XPTR_NULL );
xlist_entry_init( XPTR( cxy , &ptr->list ) );
#endif

}

/////////////////////////////////////////////////
error_t remote_spinlock_trylock( xptr_t lock_xp )
{
	reg_t               mode;
	bool_t              isAtomic = false;

	// get cluster and local pointer on remote_spinlock
	remote_spinlock_t * lock_ptr = GET_PTR( lock_xp );
	cxy_t               lock_cxy = GET_CXY( lock_xp );

	// get local pointer on local thread
	thread_t          * thread_ptr = CURRENT_THREAD;

	// disable interrupts
	hal_disable_irq( &mode );

	if( hal_remote_lw( XPTR( lock_cxy , &lock_ptr->taken ) ) == 0 )
	{
		isAtomic = hal_remote_atomic_cas( XPTR( lock_cxy , &lock_ptr->taken ) , 0 , 1 );
	}

	if( isAtomic == false )    // failure
	{
		hal_restore_irq( mode );
		return 1;
	}
	else                      // success : register lock in local thread
	{
		thread_ptr->remote_locks++;

#if DEBUG_REMOTE_SPINLOCKS
hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) ,
                XPTR( local_cxy , thread_ptr) );
xlist_add_first( XPTR( local_cxy , &thread_ptr->xlocks_root ) ,
		         XPTR( lock_cxy , &lock_ptr->list ) );
#endif

		hal_restore_irq(mode);
		return 0;
	}
}

///////////////////////////////////////////////////
void remote_spinlock_lock_busy( xptr_t     lock_xp,
                                uint32_t * irq_state )
{
	bool_t              isAtomic = false;
	reg_t               mode;
	volatile uint32_t   taken;

	// get cluster and local pointer on remote_spinlock
	remote_spinlock_t * lock_ptr = GET_PTR( lock_xp );
	cxy_t               lock_cxy = GET_CXY( lock_xp );

	// get local pointer on local thread
	thread_t          * thread_ptr = CURRENT_THREAD;

	// disable interrupts
	hal_disable_irq( &mode );

	// loop until success
	while( isAtomic == false )
	{
		taken = hal_remote_lw( XPTR( lock_cxy , &lock_ptr->taken ) );

		// try to take the lock if not already taken
		if( taken == 0 )
		{
			isAtomic = hal_remote_atomic_cas( XPTR( lock_cxy , &lock_ptr->taken ) , 0 , 1 );
		}
	}

	// register lock in thread
	thread_ptr->remote_locks++;

#if DEBUG_REMOTE_SPINLOCKS
hal_remote_swd( XPTR( lock_cxy  , &lock_ptr->owner ) ,
                XPTR( local_cxy , thread_ptr) );
xlist_add_first( XPTR( local_cxy , &thread_ptr->xlocks_root ) ,
                 XPTR( lock_cxy  , &lock_ptr->list ) );
#endif

	// irq_state must be restored when lock is released
	*irq_state = mode;

}  // end remote_spinlock_lock_busy()

////////////////////////////////////////////////////
void remote_spinlock_unlock_busy( xptr_t    lock_xp,
                                  uint32_t  irq_state )
{
	// get cluster and local pointer on remote_spinlock
	remote_spinlock_t * lock_ptr = GET_PTR( lock_xp );
	cxy_t               lock_cxy = GET_CXY( lock_xp );

	// get pointer on local thread
	thread_t          * thread_ptr = CURRENT_THREAD;

#if DEBUG_REMOTE_SPINLOCKS
hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) , XPTR_NULL );
xlist_unlink( XPTR( lock_cxy , &lock_ptr->list ) );
#endif

	hal_remote_sw ( XPTR( lock_cxy , &lock_ptr->taken ) , 0 );
	thread_ptr->remote_locks--;

    // deschedule if pending request
    thread_check_sched();
 
    // restore IRQs
	hal_restore_irq( irq_state );
}

///////////////////////////////////////////
void remote_spinlock_lock( xptr_t lock_xp )
{
	bool_t              isAtomic = false;
	reg_t               mode;
	volatile uint32_t   taken;

	// get cluster and local pointer on remote_spinlock
	remote_spinlock_t * lock_ptr = GET_PTR( lock_xp );
	cxy_t               lock_cxy = GET_CXY( lock_xp );

    // get local pointer on calling thread
    thread_t          * thread_ptr = CURRENT_THREAD;

	// disable interrupts
	hal_disable_irq( &mode );

	// loop until success
	while( isAtomic == false )
	{
		taken = hal_remote_lw( XPTR( lock_cxy , &lock_ptr->taken ) );

		// deschedule if possible when lock already taken
		if( taken != 0 )
		{
			hal_restore_irq( mode );
			if( thread_can_yield() ) sched_yield("waiting spinlock");
			hal_disable_irq( &mode );
			continue;
		}

		// try to take the lock if not already taken
		isAtomic = hal_remote_atomic_cas( XPTR( lock_cxy , &lock_ptr->taken ) , 0 , 1 );
	}

	// register lock in thread
	thread_ptr->remote_locks++;

#if DEBUG_REMOTE_SPINLOCKS
hal_remote_swd( XPTR( lock_cxy  , &lock_ptr->owner ),
                XPTR( local_cxy , thread_ptr) );
xlist_add_first( XPTR( local_cxy , &thread_ptr->xlocks_root ),
                 XPTR( lock_cxy  , &lock_ptr->list ) );
#endif

	// enable interrupts
	hal_restore_irq( mode );
}

/////////////////////////////////////////////
void remote_spinlock_unlock( xptr_t lock_xp )
{
	// get cluster and local pointer on remote_spinlock
	remote_spinlock_t * lock_ptr = GET_PTR( lock_xp );
	cxy_t               lock_cxy = GET_CXY( lock_xp );

	// get pointer on local thread
	thread_t          * thread_ptr = CURRENT_THREAD;

#if DEBUG_REMOTE_SPINLOCKS
hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) , XPTR_NULL );
xlist_unlink( XPTR( lock_cxy , &lock_ptr->list ) );
#endif

	hal_remote_sw ( XPTR( lock_cxy , &lock_ptr->taken ) , 0 );
	thread_ptr->remote_locks--;

    // deschedule if pending request
    thread_check_sched();
}