/* * Timer Manager - rtems_timer_initiate_server directive along with * the Timer Server Body and support routines * * COPYRIGHT (c) 1989-2002. * 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.OARcorp.com/rtems/license.html. * * $Id$ */ #include #include #include #include #include #include #include #include #include #include #include /* * The following chains contain the list of interval timers that are * executed in the context of the Timer Server. * * NOTE: These are prototyped in rtems/timer/timer.h but since we * do not actually use them until after the Timer Server is * initiated, we can actually declare them here and avoid forcing * them into the minimum footprint. */ Chain_Control _Timer_Ticks_chain; Chain_Control _Timer_Seconds_chain; /* * The timer used to control when the Timer Server wakes up to service * "when" timers. * * NOTE: This should NOT be used outside this file. */ Watchdog_Control _Timer_Seconds_timer; /*PAGE * * _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. * * Input parameters: * Ignored - the task argument is ignored * * Output parameters: NONE */ Thread _Timer_Server_body( unsigned32 ignored ) { Watchdog_Interval snapshot; Watchdog_Interval ticks_last_time; Watchdog_Interval seconds_last_time; Watchdog_Interval ticks; /* * Initialize the "last time" markers to indicate the timer that * the server was initiated. */ ticks_last_time = _Watchdog_Ticks_since_boot; seconds_last_time = _TOD_Seconds_since_epoch; _Thread_Disable_dispatch(); while(1) { /* * Block until there is something to do. */ _Thread_Set_state( _Timer_Server, STATES_DELAYING ); _Timer_Server_reset( TIMER_SERVER_RESET_TICKS ); _Timer_Server_reset( TIMER_SERVER_RESET_SECONDS ); _Thread_Enable_dispatch(); /* * Disable dispatching while processing the timers since we want * to mimic the environment that non-task-based TSRs execute in. * This ensures that the primary difference is that _ISR_Nest_level * is 0 for task-based timers and non-zero for the others. */ _Thread_Disable_dispatch(); /* * Process the ticks chain */ snapshot = _Watchdog_Ticks_since_boot; ticks = snapshot - ticks_last_time; ticks_last_time = snapshot; _Watchdog_Adjust( &_Timer_Ticks_chain, WATCHDOG_FORWARD, 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 > seconds_last_time ) { /* * This path is for normal forward movement and cases where the * TOD has been set forward. */ ticks = snapshot - seconds_last_time; _Watchdog_Adjust( &_Timer_Seconds_chain, WATCHDOG_FORWARD, ticks ); } else if ( snapshot < seconds_last_time ) { /* * The current TOD is before the last TOD which indicates that * TOD has been set backwards. */ ticks = seconds_last_time - snapshot; _Watchdog_Adjust( &_Timer_Seconds_chain, WATCHDOG_BACKWARD, ticks ); } seconds_last_time = snapshot; } } /*PAGE * * 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. * * Input parameters: * stack_size - stack size in bytes * attribute_set - thread attributes * * Output parameters: * RTEMS_SUCCESSFUL - if successful * error code - if unsuccessful */ rtems_status_code rtems_timer_initiate_server( unsigned32 stack_size, rtems_attribute attribute_set ) { rtems_id id; rtems_status_code status; /* * Just to make sure the test versus create/start operation are atomic. */ _Thread_Disable_dispatch(); if ( _Timer_Server ) { _Thread_Enable_dispatch(); return RTEMS_INCORRECT_STATE; } /* * Create the Timer Server with the name the name of "TIME". The priority * is always "0" which makes it higher than any other task in the system. * It is also always NO_PREEMPT so it looks like an interrupt to other tasks. */ status = rtems_task_create( rtems_build_name( 'T', 'I', 'M', 'E' ), 1, /* create with priority 1 since 0 is illegal */ stack_size, /* let user specify stack size */ RTEMS_NO_PREEMPT, /* no preempt is like an interrupt */ attribute_set, /* user may want floating point */ &id /* get the id back */ ); if (status) { _Thread_Enable_dispatch(); return status; } 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. */ _Thread_Enable_dispatch(); return status; } /* * 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) ); /* * A priority of 0, higher than any user task, combined with no preemption * makes this task the highest priority in any application. It can be * viewed as a low priority interrupt. The FALSE argument indicates * that the task is to be appended (not prepended) to its priority * chain at the end of this operation. */ _Thread_Change_priority( _Timer_Server, 0, FALSE ); /* * 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 ); _Thread_Enable_dispatch(); return RTEMS_SUCCESSFUL; } /*PAGE * * _Timer_Server_reset * * This routine resets the timers which determine when the Timer Server * will wake up next to service task-based timers. * * Input parameters: * do_ticks - TRUE indicates to process the ticks list * FALSE indicates to process the seconds list * * Output parameters: NONE */ void _Timer_Server_reset( Timer_Server_reset_mode reset_mode ) { Watchdog_Interval units; switch ( reset_mode ) { case TIMER_SERVER_RESET_TICKS: _Watchdog_Remove( &_Timer_Server->Timer ); units = ((Watchdog_Control *)_Timer_Ticks_chain.first)->delta_interval; _Watchdog_Insert_ticks( &_Timer_Server->Timer, units ); break; case TIMER_SERVER_RESET_SECONDS: _Watchdog_Remove( &_Timer_Seconds_timer ); units = ((Watchdog_Control *)_Timer_Seconds_chain.first)->delta_interval; _Watchdog_Insert_seconds( &_Timer_Seconds_timer, units ); break; } }