/** * @file timerserver.c * * Timer Manager - rtems_timer_initiate_server directive along with * the Timer Server Body and support routines * * @note Data specific to the Timer Server is declared in this * file as the Timer Server so it does not have to be in the * minimum footprint. It is only really required when * task-based timers are used. Since task-based timers can * not be started until the server is initiated, this structure * does not have to be initialized until then. */ /* COPYRIGHT (c) 1989-2008. * On-Line Applications Research Corporation (OAR). * * The license and distribution terms for this file may be * found in the file LICENSE in this distribution or at * http://www.rtems.com/license/LICENSE. * * $Id$ */ #if HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include #include #include #include #include #include #include /** * This chain contains the list of interval timers that are * executed in the context of the Timer Server. */ Chain_Control _Timer_Ticks_chain; /** * This chain contains the list of time of day timers that are * executed in the context of the Timer Server. */ Chain_Control _Timer_Seconds_chain; /** * This chain holds the set of timers to be inserted when the * server runs again. */ Chain_Control _Timer_To_be_inserted; /** * This variables keeps track of the last time the Timer Server actually * processed the ticks chain. */ Watchdog_Interval _Timer_Server_ticks_last_time; /** * This variable keeps track of the last time the Timer Server actually * processed the seconds chain. */ Watchdog_Interval _Timer_Server_seconds_last_time; /** * This is the timer used to control when the Timer Server wakes up to * service "when" timers. * * @note The timer in the Timer Server TCB is used for ticks timer. */ Watchdog_Control _Timer_Seconds_timer; /** * This method is used to temporarily disable updates to the * Ticks Timer Chain managed by the Timer Server. */ #define _Timer_Server_stop_ticks_timer() \ _Watchdog_Remove( &_Timer_Server->Timer ) /** * This method is used to temporarily disable updates to the * Seconds Timer Chain managed by the Timer Server. */ #define _Timer_Server_stop_seconds_timer() \ _Watchdog_Remove( &_Timer_Seconds_timer ); /** * This method resets a timer and places it on the Ticks chain. It * is assumed that the timer has already been canceled. */ #define _Timer_Server_reset_ticks_timer() \ do { \ if ( !_Chain_Is_empty( &_Timer_Ticks_chain ) ) { \ _Watchdog_Insert_ticks( &_Timer_Server->Timer, \ ((Watchdog_Control *)_Timer_Ticks_chain.first)->delta_interval ); \ } \ } while (0) /** * This method resets a timer and places it on the Seconds chain. It * is assumed that the timer has already been canceled. */ #define _Timer_Server_reset_seconds_timer() \ do { \ if ( !_Chain_Is_empty( &_Timer_Seconds_chain ) ) { \ _Watchdog_Insert_seconds( &_Timer_Seconds_timer, \ ((Watchdog_Control *)_Timer_Seconds_chain.first)->delta_interval ); \ } \ } while (0) /** * @brief _Timer_Server_process_insertions * * This method processes the set of timers scheduled for insertion * onto one of the Timer Server chains. * * @note It is only to be called from the Timer Server task. */ static void _Timer_Server_process_insertions(void) { Timer_Control *the_timer; while ( 1 ) { the_timer = (Timer_Control *) _Chain_Get( &_Timer_To_be_inserted ); if ( the_timer == NULL ) break; if ( the_timer->the_class == TIMER_INTERVAL_ON_TASK ) { _Watchdog_Insert( &_Timer_Ticks_chain, &the_timer->Ticker ); } else if ( the_timer->the_class == TIMER_TIME_OF_DAY_ON_TASK ) { _Watchdog_Insert( &_Timer_Seconds_chain, &the_timer->Ticker ); } /* * Insert the timers that have been requested to be inserted. */ _Timer_Server_process_insertions(); } } /** * @brief _Timer_Server_process_ticks_chain * * This routine is responsible for adjusting the list of task-based * interval timers to reflect the passage of time. * * @param[in] to_fire will contain the set of timers that are to be fired. * * @note It is only to be called from the Timer Server task. */ static void _Timer_Server_process_ticks_chain( Chain_Control *to_fire ) { Watchdog_Interval snapshot; Watchdog_Interval ticks; snapshot = _Watchdog_Ticks_since_boot; if ( snapshot >= _Timer_Server_ticks_last_time ) ticks = snapshot - _Timer_Server_ticks_last_time; else ticks = (0xFFFFFFFF - _Timer_Server_ticks_last_time) + snapshot; _Timer_Server_ticks_last_time = snapshot; _Watchdog_Adjust_to_chain( &_Timer_Ticks_chain, ticks, to_fire ); } /** * @brief _Timer_Server_process_seconds_chain * * This routine is responsible for adjusting the list of task-based * time of day timers to reflect the passage of time. * * @param[in] to_fire will contain the set of timers that are to be fired. * * @note It is only to be called from the Timer Server task. */ static void _Timer_Server_process_seconds_chain( Chain_Control *to_fire ) { Watchdog_Interval snapshot; Watchdog_Interval ticks; /* * Process the seconds chain. Start by checking that the Time * of Day (TOD) has not been set backwards. If it has then * we want to adjust the _Timer_Seconds_chain to indicate this. */ snapshot = _TOD_Seconds_since_epoch; if ( snapshot > _Timer_Server_seconds_last_time ) { /* * This path is for normal forward movement and cases where the * TOD has been set forward. */ ticks = snapshot - _Timer_Server_seconds_last_time; _Watchdog_Adjust_to_chain( &_Timer_Seconds_chain, ticks, to_fire ); } else if ( snapshot < _Timer_Server_seconds_last_time ) { /* * The current TOD is before the last TOD which indicates that * TOD has been set backwards. */ ticks = _Timer_Server_seconds_last_time - snapshot; _Watchdog_Adjust( &_Timer_Seconds_chain, WATCHDOG_BACKWARD, ticks ); } _Timer_Server_seconds_last_time = snapshot; } /** * @brief _Timer_Server_body * * This is the server for task based timers. This task executes whenever * a task-based timer should fire. It services both "after" and "when" * timers. It is not created automatically but must be created explicitly * by the application before task-based timers may be initiated. * * @param[in] ignored is the the task argument that is ignored */ Thread _Timer_Server_body( uint32_t ignored ) { Chain_Control to_fire; _Chain_Initialize_empty( &to_fire ); /* * Initialize the "last time" markers to indicate the timer that * the server was initiated. */ _Timer_Server_ticks_last_time = _Watchdog_Ticks_since_boot; _Timer_Server_seconds_last_time = _TOD_Seconds_since_epoch; /* * Insert the timers that were inserted before we got to run. * This should be done with dispatching disabled. */ _Thread_Disable_dispatch(); _Timer_Server_process_insertions(); _Thread_Enable_dispatch(); while(1) { /* * Block until there is something to do. */ _Thread_Disable_dispatch(); _Thread_Set_state( _Timer_Server, STATES_DELAYING ); _Timer_Server_reset_ticks_timer(); _Timer_Server_reset_seconds_timer(); _Thread_Enable_dispatch(); /******************************************************************** ******************************************************************** **** TIMER SERVER BLOCKS HERE **** ******************************************************************** ********************************************************************/ /* * Disable dispatching while processing the timers since we want * the removal of the timers from the chain to be atomic. * * NOTE: Dispatching is disabled for interrupt based TSRs. * Dispatching is enabled for task based TSRs so they * can temporarily malloc memory or block. * _ISR_Nest_level is 0 for task-based TSRs and non-zero * for the others. */ _Thread_Disable_dispatch(); /* * At this point, at least one of the timers this task relies * upon has fired. Stop them both while we process any outstanding * timers. Before we block, we will restart them. */ _Timer_Server_stop_ticks_timer(); _Timer_Server_stop_seconds_timer(); /* * Remove all the timers that need to fire so we can invoke them * outside the critical section. */ _Timer_Server_process_ticks_chain( &to_fire ); _Timer_Server_process_seconds_chain( &to_fire ); /* * Insert the timers that have been requested to be inserted. */ _Timer_Server_process_insertions(); /* * Enable dispatching to process the set that are ready "to fire." */ _Thread_Enable_dispatch(); /* * Now we actually invoke the TSR for all the timers that fired. * This is done with dispatching */ while (1) { Watchdog_Control *watch; ISR_Level level; _ISR_Disable( level ); watch = (Watchdog_Control *) _Chain_Get_unprotected( &to_fire ); if ( watch == NULL ) { _ISR_Enable( level ); break; } watch->state = WATCHDOG_INACTIVE; _ISR_Enable( level ); (*watch->routine)( watch->id, watch->user_data ); } } return 0; /* unreached - only to remove warnings */ } /** * This method schedules the insertion of timers on the proper list. It * wakes up the Timer Server task to process the insertion. * * @param[in] the_timer is the timer to insert * * @note It is highly likely the executing task will be preempted after * the directive invoking this is executed. */ static void _Timer_Server_schedule_operation_method( Timer_Control *the_timer ) { _Chain_Append( &_Timer_To_be_inserted, &the_timer->Object.Node ); _Watchdog_Remove( &_Timer_Server->Timer ); _Thread_Delay_ended( _Timer_Server->Object.id, NULL ); } /** * @brief rtems_timer_initiate_server * * This directive creates and starts the server for task-based timers. * It must be invoked before any task-based timers can be initiated. * * @param[in] priority is the timer server priority * @param[in] stack_size is the stack size in bytes * @param[in] attribute_set is the timer server attributes * * @return This method returns RTEMS_SUCCESSFUL if successful and an * error code otherwise. */ rtems_status_code rtems_timer_initiate_server( uint32_t priority, uint32_t stack_size, rtems_attribute attribute_set ) { rtems_id id; rtems_status_code status; rtems_task_priority _priority; static bool initialized = false; bool tmpInitialized; /* * Make sure the requested priority is valid. The if is * structured so we check it is invalid before looking for * a specific invalid value as the default. */ _priority = priority; if ( !_RTEMS_tasks_Priority_is_valid( priority ) ) { if ( priority != RTEMS_TIMER_SERVER_DEFAULT_PRIORITY ) return RTEMS_INVALID_PRIORITY; _priority = 0; } /* * Just to make sure this is only called once. */ _Thread_Disable_dispatch(); tmpInitialized = initialized; initialized = true; _Thread_Enable_dispatch(); if ( tmpInitialized ) return RTEMS_INCORRECT_STATE; /* * Initialize the set of timers to be inserted by the server. */ _Chain_Initialize_empty( &_Timer_To_be_inserted ); /* * Create the Timer Server with the name the name of "TIME". The attribute * RTEMS_SYSTEM_TASK allows us to set a priority to 0 which will makes it * higher than any other task in the system. It can be viewed as a low * priority interrupt. It is also always NO_PREEMPT so it looks like * an interrupt to other tasks. * * We allow the user to override the default priority because the Timer * Server can invoke TSRs which must adhere to language run-time or * other library rules. For example, if using a TSR written in Ada the * Server should run at the same priority as the priority Ada task. * Otherwise, the priority ceiling for the mutex used to protect the * GNAT run-time is violated. */ status = rtems_task_create( _Objects_Build_name('T','I','M','E'), /* "TIME" */ _priority, /* create with priority 1 since 0 is illegal */ stack_size, /* let user specify stack size */ RTEMS_NO_PREEMPT, /* no preempt is like an interrupt */ /* user may want floating point but we need */ /* system task specified for 0 priority */ attribute_set | RTEMS_SYSTEM_TASK, &id /* get the id back */ ); if (status) { initialized = false; return status; } /* * Do all the data structure initialization before starting the * Timer Server so we do not have to have a critical section. */ /* * We work with the TCB pointer, not the ID, so we need to convert * to a TCB pointer from here out. * * NOTE: Setting the pointer to the Timer Server TCB to a value other than * NULL indicates that task-based timer support is initialized. */ _Timer_Server = (Thread_Control *)_Objects_Get_local_object( &_RTEMS_tasks_Information, _Objects_Get_index(id) ); /* * Initialize the timer lists that the server will manage. */ _Chain_Initialize_empty( &_Timer_Ticks_chain ); _Chain_Initialize_empty( &_Timer_Seconds_chain ); /* * Initialize the timers that will be used to control when the * Timer Server wakes up and services the task-based timers. */ _Watchdog_Initialize( &_Timer_Server->Timer, _Thread_Delay_ended, id, NULL ); _Watchdog_Initialize( &_Timer_Seconds_timer, _Thread_Delay_ended, id, NULL ); /* * Initialize the pointer to the timer reset method so applications * that do not use the Timer Server do not have to pull it in. */ _Timer_Server_schedule_operation = _Timer_Server_schedule_operation_method; /* * Start the timer server */ status = rtems_task_start( id, /* the id from create */ (rtems_task_entry) _Timer_Server_body, /* the timer server entry point */ 0 /* there is no argument */ ); if (status) { /* * One would expect a call to rtems_task_delete() here to clean up * but there is actually no way (in normal circumstances) that the * start can fail. The id and starting address are known to be * be good. If this service fails, something is weirdly wrong on the * target such as a stray write in an ISR or incorrect memory layout. */ initialized = false; } return status; }