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Diffstat (limited to 'cpukit/rtems/src/timerserver.c')
| -rw-r--r-- | cpukit/rtems/src/timerserver.c | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/cpukit/rtems/src/timerserver.c b/cpukit/rtems/src/timerserver.c new file mode 100644 index 0000000000..76fa532e91 --- /dev/null +++ b/cpukit/rtems/src/timerserver.c @@ -0,0 +1,288 @@ +/* + * 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 <rtems/system.h> +#include <rtems/rtems/status.h> +#include <rtems/rtems/support.h> +#include <rtems/score/object.h> +#include <rtems/score/thread.h> +#include <rtems/rtems/timer.h> +#include <rtems/score/tod.h> +#include <rtems/score/watchdog.h> + +#include <rtems/rtems/tasks.h> +#include <rtems/score/thread.h> + +/* + * 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( + 0x4954454d, /* "TIME" */ + 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; + } +} + |