/*
 * Definition of the scheduler plugin interface.
 *
 */
#ifndef _LINUX_SCHED_PLUGIN_H_
#define _LINUX_SCHED_PLUGIN_H_

#include <linux/sched.h>

/* struct for semaphore with priority inheritance */
struct pi_semaphore {
	atomic_t count;
	int sleepers;
	wait_queue_head_t wait;
	union {
		/* highest-prio holder/waiter */
		struct task_struct *task;
		struct task_struct* cpu_task[NR_CPUS];
	} hp;
	/* current lock holder */
	struct task_struct *holder;
};

/************************ setup/tear down ********************/

typedef long (*activate_plugin_t) (void);
typedef long (*deactivate_plugin_t) (void);



/********************* scheduler invocation ******************/

/*  Plugin-specific realtime tick handler */
typedef void (*scheduler_tick_t) (struct task_struct *cur);
/* Novell make sched decision function */
typedef struct task_struct* (*schedule_t)(struct task_struct * prev);
/* Clean up after the task switch has occured.
 * This function is called after every (even non-rt) task switch.
 */
typedef void (*finish_switch_t)(struct task_struct *prev);


/********************* task state changes ********************/

/* Called to setup a new real-time task.
 * Release the first job, enqueue, etc.
 * Task may already be running.
 */
typedef void (*task_new_t) (struct task_struct *task,
			    int on_rq,
			    int running);

/* Called to re-introduce a task after blocking.
 * Can potentially be called multiple times.
 */
typedef void (*task_wake_up_t) (struct task_struct *task);
/* called to notify the plugin of a blocking real-time task
 * it will only be called for real-time tasks and before schedule is called */
typedef void (*task_block_t)  (struct task_struct *task);
/* Called when a real-time task exits or changes to a different scheduling
 * class.
 * Free any allocated resources
 */
typedef void (*task_exit_t)    (struct task_struct *);

/* Called when the new_owner is released from the wait queue
 * it should now inherit the priority from sem, _before_ it gets readded
 * to any queue
 */
typedef long (*inherit_priority_t) (struct pi_semaphore *sem,
				    struct task_struct *new_owner);

/* Called when the current task releases a semahpore where it might have
 * inherited a piority from
 */
typedef long (*return_priority_t) (struct pi_semaphore *sem);

/* Called when a task tries to acquire a semaphore and fails. Check if its
 * priority is higher than that of the current holder.
 */
typedef long (*pi_block_t) (struct pi_semaphore *sem, struct task_struct *t);




/********************* sys call backends  ********************/
/* This function causes the caller to sleep until the next release */
typedef long (*complete_job_t) (void);

typedef long (*admit_task_t)(struct task_struct* tsk);

typedef void (*release_at_t)(struct task_struct *t, lt_t start);

struct sched_plugin {
	struct list_head	list;
	/* 	basic info 		*/
	char 			*plugin_name;

	/*	setup			*/
	activate_plugin_t	activate_plugin;
	deactivate_plugin_t	deactivate_plugin;

#ifdef CONFIG_SRP
	unsigned int		srp_active;
#endif

	/* 	scheduler invocation 	*/
	scheduler_tick_t        tick;
	schedule_t 		schedule;
	finish_switch_t 	finish_switch;

	/*	syscall backend 	*/
	complete_job_t 		complete_job;
	release_at_t		release_at;

	/*	task state changes 	*/
	admit_task_t		admit_task;

        task_new_t 		task_new;
	task_wake_up_t		task_wake_up;
	task_block_t		task_block;
	task_exit_t 		task_exit;

#ifdef CONFIG_FMLP
	/*     priority inheritance 	*/
	unsigned int		fmlp_active;
	inherit_priority_t	inherit_priority;
	return_priority_t	return_priority;
	pi_block_t		pi_block;
#endif
} __attribute__ ((__aligned__(SMP_CACHE_BYTES)));


extern struct sched_plugin *litmus;

int register_sched_plugin(struct sched_plugin* plugin);
struct sched_plugin* find_sched_plugin(const char* name);
int print_sched_plugins(char* buf, int max);

static inline int srp_active(void)
{
#ifdef CONFIG_SRP
	return litmus->srp_active;
#else
	return 0;
#endif
}
static inline int fmlp_active(void)
{
#ifdef CONFIG_FMLP
	return litmus->fmlp_active;
#else
	return 0;
#endif
}

extern struct sched_plugin linux_sched_plugin;

#endif