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/*

 * Copyright (c) 2007 Jan Hudecek

 * Copyright (c) 2006 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.

 */

/** @addtogroup genericddi

 * @{

 */

/** @file tasklet.c

 *  @brief Tasklet implementation

 */

#include <arch.h>

#include <config.h>

#include <arch/types.h>

#include <arch/asm.h>

#include <proc/tasklet.h>

#include <synch/spinlock.h>

#include <time/delay.h>

#include <proc/thread.h>

#include <panic.h>

#include <print.h>

#include <synch/waitq.h>

#include <cpu.h>

#include <proc/scheduler.h>

/** Timeout length in the tasklet thread */

#define TASKLET_THREAD_SLEEPDELAY 10000

///** Priority of the tasklet thread */

#define TASKLET_THREAD_PRIORITY 1

/** Tasklet state enum */

typedef enum  {

TASKLET_STATE_NOTACTIVE = 0,

TASKLET_STATE_SCHEDULED = 1,

TASKLET_STATE_RUNNING = 2,

TASKLET_STATE_DISABLED = 4

} tasklet_state_enum;

/** Spinlock protecting list of tasklets */

SPINLOCK_INITIALIZE(tasklet_lock);

/** array of tasklet lists for every CPU */

tasklet_descriptor_t** tasklet_list;

/** Initializes tasklets - except for the tasklet thread */

void tasklet_init(void)

{

    int i;

    tasklet_list=malloc(sizeof(tasklet_descriptor_t*)*config.cpu_count,0);

    if (tasklet_list==0)

        panic_printf("tasklet list mem not allocated\n");

    for(i=0;i<config.cpu_count;i++) {

        tasklet_list[i]=0;

    }

    spinlock_initialize(&tasklet_lock, "tasklet_lock");

}

/**

* Creates and runs the tasklet thread

*

*  @param kernel_task Pointer to the kernel task - for create_thread

*/

void tasklet_run_tasklet_thread(task_t * kernel_task)

{

    //create the tasklet_thread, it's wired to the current cpu, we'll migrate it ourselves

    thread_t* t= thread_create(&tasklet_thread, NULL, kernel_task, THREAD_FLAG_WIRED, "tasklet_thread", false);

    if (t==NULL) {

        panic_printf("tasklet thread not created\n");

    } else {

        spinlock_lock(&t->lock);   

        //we'll default on the first CPU

        t->cpu = &cpus[0];

        t->priority = TASKLET_THREAD_PRIORITY;

        spinlock_unlock(&t->lock);

        thread_ready(t);

    }

}

/** Thread which keeps executing scheduled enabled tasklets

* @param data not used

*/

void tasklet_thread(void* data)

{

#ifdef CONFIG_SMP

    int current_cpu, new_cpu ;

    cpu_t *cpu;

#endif

    waitq_t  wq;

    waitq_initialize(&wq);

    //the infinite loop

    while (true) {

        //execute any scheduled tasklets

        tasklet_do();

#ifdef CONFIG_SMP

        //check whether other CPUs have tasklets to execute

        if (config.cpu_active>1) {

            current_cpu = CPU->id;

            //find the first cpu with nonempty tasklet_list 

            for (new_cpu = (current_cpu + 1) % config.cpu_count; new_cpu!=current_cpu && tasklet_list[new_cpu]==0 ;

                    new_cpu=(new_cpu + 1)% config.cpu_count);

            //if we found a CPU with unsatisfied tasklet schedule to run there. It must be active!

            if (new_cpu!=current_cpu && cpus[new_cpu].active) {

                //we need to migrate this thread to CPU with id new_cpu

                cpu = &cpus[new_cpu];

                spinlock_lock(&THREAD->lock);

                //move tasklet_thread on the new_cpu 

                THREAD->cpu = cpu;

                spinlock_unlock(&THREAD->lock);

            }

        }

#endif

        waitq_sleep_timeout(&wq, (uint32_t)TASKLET_THREAD_SLEEPDELAY, 0);

    }

}

/** Initializes tasklet structure

* @param func tasklet callback function to be called

* @param data pointer to be passed to the tasklet function

*/

tasklet_descriptor_t* tasklet_register(void (*func)(void* data), void* data)

{

    tasklet_descriptor_t* tasklet=malloc(sizeof(tasklet_descriptor_t),0);

    tasklet->data = data;

    tasklet->func = func;

    tasklet->state = TASKLET_STATE_NOTACTIVE;

    tasklet->next = 0;

    return tasklet;

}

/** Schedules the tasklet for execution on current CPU

* @param t tasklet to be scheduled

*/

void tasklet_schedule(tasklet_descriptor_t* t)

{

    tasklet_schedule_SMP(t, CPU->id);

}

/** Schedules the tasklet for execution on id CPU

* @param t tasklet to be scheduled

* @param id CPU id on which the tasklet will be scheduled

*/

void tasklet_schedule_SMP(tasklet_descriptor_t* t, uint32_t id)

{

    spinlock_lock(&tasklet_lock);

    //clear notactive, running and scheduled flags

    t->state &= TASKLET_STATE_DISABLED;

    //set the scheduled flag

    t->state |= TASKLET_STATE_SCHEDULED;

    t->next=tasklet_list[id];

    tasklet_list[id]=t;

    spinlock_unlock(&tasklet_lock);

}

/** Tasklet will not be run, even if scheduled

* @param t tasklet to be disabled

*/

void tasklet_disable(tasklet_descriptor_t* t)

{

    spinlock_lock(&tasklet_lock);

    //set the disabled flag

    t->state |= TASKLET_STATE_DISABLED;

    spinlock_unlock(&tasklet_lock);

}

/** Tasklet will be run if scheduled

* @param t tasklet to be enabled

*/

void tasklet_enable(tasklet_descriptor_t* t)

{

    spinlock_lock(&tasklet_lock);

    //clear the disabled flag

    t->state &= ~TASKLET_STATE_DISABLED;

    spinlock_unlock(&tasklet_lock);

}

/** Executes scheduled enabled tasklets on current CPU

* this function could be called from other parts of kernel */

void tasklet_do(void)

{

    spinlock_lock(&tasklet_lock);

    tasklet_descriptor_t* t = tasklet_list[CPU->id];

    if (t) {

        //empty the tasklet_list

        tasklet_list[CPU->id]=0;

        spinlock_unlock(&tasklet_lock);

        do {

            if (!(t->state & TASKLET_STATE_DISABLED)) {

                if (t->func) {

                    t->state = TASKLET_STATE_RUNNING;

                    t->func(t->data);

                    //clear running flag, set not active 

                    t->state &= ~TASKLET_STATE_RUNNING;

                    t->state |= TASKLET_STATE_NOTACTIVE;

                } else

                    panic_printf("tasklet func NULL\n");

            } else {  

                //return it back to the queue of scheduled tasklets

                spinlock_lock(&tasklet_lock);  

                t->next = tasklet_list[CPU->id];

                tasklet_list[CPU->id] = t;

                spinlock_unlock(&tasklet_lock);

            }

            t=t->next;

        }

        while (t);

    }

    else

        spinlock_unlock(&tasklet_lock);

}

/** Frees the tasklet structure when no longer needed. The function doesn't provide

*   any synchronization, the caller must be sure, that the tasklet is not scheduled.

*

* @param tasklet to be freed

*/

void tasklet_free(tasklet_descriptor_t* t)

{

    spinlock_lock(&tasklet_lock);

    if (t->state == TASKLET_STATE_NOTACTIVE)

        free(t);

    else

        panic_printf("attempting to free an active tasklet");

    spinlock_unlock(&tasklet_lock);

}