alarm.c

xenomai 很好的linux实时补丁

    xeno_mark_deleted(alarm);

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

/**
 * @fn int rt_alarm_start(RT_ALARM *alarm,RTIME value,RTIME interval)
 * @brief Start an alarm.
 *
 * Program the trigger date of an alarm object. An alarm can be either
 * periodic or oneshot, depending on the reload value passed to this
 * routine. The given alarm must have been previously created by a
 * call to rt_alarm_create().
 *
 * Alarm handlers are always called on behalf of Xenomai's internal timer
 * tick handler, so the Xenomai services which can be called from such
 * handlers are restricted to the set of services available on behalf
 * of any ISR.
 *
 * This service overrides any previous setup of the expiry date and
 * reload interval for the given alarm.
 *
 * @param alarm The descriptor address of the affected alarm.
 *
 * @param value The relative date of the initial alarm shot, expressed
 * in clock ticks (see note).
 *
 * @param interval The reload value of the alarm. It is a periodic
 * interval value to be used for reprogramming the next alarm shot,
 * expressed in clock ticks (see note). If @a interval is equal to
 * TM_INFINITE, the alarm will not be reloaded after it has expired.
 *
 * @return 0 is returned upon success. Otherwise:
 *
 * - -EINVAL is returned if @a alarm is not a alarm descriptor.
 *
 * Environments:
 *
 * This service can be called from:
 *
 * - Kernel module initialization/cleanup code
 * - Interrupt service routine
 * - Kernel-based task
 * - User-space task
 *
 * Rescheduling: never.
 *
 * @note This service is sensitive to the current operation mode of
 * the system timer, as defined by the rt_timer_start() service. In
 * periodic mode, clock ticks are interpreted as periodic jiffies. In
 * oneshot mode, clock ticks are interpreted as nanoseconds.
 */

int rt_alarm_start (RT_ALARM *alarm,
		    RTIME value,
		    RTIME interval)
{
    int err = 0;
    spl_t s;

    xnlock_get_irqsave(&nklock,s);

    alarm = xeno_h2obj_validate(alarm,XENO_ALARM_MAGIC,RT_ALARM);

    if (!alarm)
        {
        err = xeno_handle_error(alarm,XENO_ALARM_MAGIC,RT_ALARM);
        goto unlock_and_exit;
        }

    xntimer_start(&alarm->timer_base,value,interval);

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

/**
 * @fn int rt_alarm_stop(RT_ALARM *alarm)
 * @brief Stop an alarm.
 *
 * Disarm an alarm object previously armed using rt_alarm_start() so
 * that it will not trigger until is is re-armed.
 *
 * @param alarm The descriptor address of the released alarm.
 *
 * @return 0 is returned upon success. Otherwise:
 *
 * - -EINVAL is returned if @a alarm is not a alarm descriptor.
 *
 * - -EIDRM is returned if @a alarm is a deleted alarm descriptor.
 *
 * Environments:
 *
 * This service can be called from:
 *
 * - Kernel module initialization/cleanup code
 * - Interrupt service routine
 * - Kernel-based task
 * - User-space task
 *
 * Rescheduling: never.
 */

int rt_alarm_stop (RT_ALARM *alarm)

{
    int err = 0;
    spl_t s;

    xnlock_get_irqsave(&nklock,s);

    alarm = xeno_h2obj_validate(alarm,XENO_ALARM_MAGIC,RT_ALARM);

    if (!alarm)
        {
        err = xeno_handle_error(alarm,XENO_ALARM_MAGIC,RT_ALARM);
        goto unlock_and_exit;
        }

    xntimer_stop(&alarm->timer_base);

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

/**
 * @fn int rt_alarm_inquire(RT_ALARM *alarm, RT_ALARM_INFO *info)
 * @brief Inquire about an alarm.
 *
 * Return various information about the status of a given alarm.
 *
 * @param alarm The descriptor address of the inquired alarm.
 *
 * @param info The address of a structure the alarm information will
 * be written to.
 *
 * The expiration date returned in the information block is converted
 * to the current time unit. The special value TM_INFINITE is returned
 * if @a alarm is currently inactive/stopped. In single-shot mode, it
 * might happen that the alarm has already expired when this service
 * is run (even if the associated handler has not been fired yet); in
 * such a case, 1 is returned.
 *
 * @return 0 is returned and status information is written to the
 * structure pointed at by @a info upon success. Otherwise:
 *
 * - -EINVAL is returned if @a alarm is not a alarm descriptor.
 *
 * - -EIDRM is returned if @a alarm is a deleted alarm descriptor.
 *
 * Environments:
 *
 * This service can be called from:
 *
 * - Kernel module initialization/cleanup code
 * - Interrupt service routine
 * - Kernel-based task
 * - User-space task
 *
 * Rescheduling: never.
 */

int rt_alarm_inquire (RT_ALARM *alarm,
                      RT_ALARM_INFO *info)
{
    int err = 0;
    spl_t s;

    xnlock_get_irqsave(&nklock,s);

    alarm = xeno_h2obj_validate(alarm,XENO_ALARM_MAGIC,RT_ALARM);

    if (!alarm)
        {
        err = xeno_handle_error(alarm,XENO_ALARM_MAGIC,RT_ALARM);
        goto unlock_and_exit;
        }
    
    strcpy(info->name,alarm->name);
    info->expiration = xntimer_get_timeout(&alarm->timer_base);
    info->expiries = alarm->expiries;

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

/**
 * @fn int rt_alarm_create(RT_ALARM *alarm,const char *name)
 * @brief Create an alarm object from user-space.
 *
 * Initializes an alarm object from a user-space application.  Alarms
 * can be made periodic or oneshot, depending on the reload interval
 * value passed to rt_alarm_start() for them. In this mode, the basic
 * principle is to define some alarm server task which routinely waits
 * for the next incoming alarm event through the rt_alarm_wait()
 * syscall.
 *
 * @param alarm The address of an alarm descriptor Xenomai will use to
 * store the alarm-related data.  This descriptor must always be valid
 * while the alarm is active therefore it must be allocated in
 * permanent memory.
 *
 * @param name An ASCII string standing for the symbolic name of the
 * alarm. When non-NULL and non-empty, this string is copied to a safe
 * place into the descriptor, and passed to the registry package if
 * enabled for indexing the created alarm.
 *
 * @return 0 is returned upon success. Otherwise:
 *
 * - -ENOMEM is returned if the system fails to get enough dynamic
 * memory from the global real-time heap in order to register the
 * alarm.
 *
 * - -EEXIST is returned if the @a name is already in use by some
 * registered object.
 *
 * - -EPERM is returned if this service was called from an
 * asynchronous context.
 *
 * Environments:
 *
 * This service can be called from:
 *
 * - User-space task
 *
 * Rescheduling: possible.
 *
 * @note It is possible to combine kernel-based alarm handling with
 * waiter threads pending on the same alarm object from user-space
 * through the rt_alarm_wait() service. For this purpose, the
 * rt_alarm_handler() routine which is internally invoked to wake up
 * alarm servers in user-space is accessible to user-provided alarm
 * handlers in kernel space, and should be called from there in order
 * to unblock any thread sleeping on the rt_alarm_wait() service.
 */

/**
 * @fn int rt_alarm_wait(RT_ALARM *alarm)
 * @brief Wait for the next alarm shot.
 *
 * This user-space only call allows the current task to suspend
 * execution until the specified alarm triggers. The priority of the
 * current task is raised above all other Xenomai tasks - except those
 * also undergoing an alarm or interrupt wait (see rt_intr_wait()) -
 * so that it would preempt any of them under normal circumstances
 * (i.e. no scheduler lock).
 *
 * @param alarm The descriptor address of the awaited alarm.
 *
 * @return 0 is returned upon success. Otherwise:
 *
 * - -EINVAL is returned if @a alarm is not an alarm descriptor.
 *
 * - -EPERM is returned if this service was called from a context
 * which cannot sleep (e.g. interrupt, non-realtime or scheduler
 * locked).
 *
 * - -EIDRM is returned if @a alarm is a deleted alarm descriptor,
 * including if the deletion occurred while the caller was waiting for
 * its next shot.
 *
 * - -EINTR is returned if rt_task_unblock() has been called for the
 * current task before the next alarm shot.
 *
 * Environments:
 *
 * This service can be called from:
 *
 * - User-space task
 *
 * Rescheduling: always.
 */

/*@}*/

EXPORT_SYMBOL(rt_alarm_create);
EXPORT_SYMBOL(rt_alarm_delete);
EXPORT_SYMBOL(rt_alarm_start);
EXPORT_SYMBOL(rt_alarm_stop);
EXPORT_SYMBOL(rt_alarm_inquire);