diff options
Diffstat (limited to 'cpukit/rtems/src/timerserver.c')
| -rw-r--r-- | cpukit/rtems/src/timerserver.c | 317 |
1 files changed, 317 insertions, 0 deletions
diff --git a/cpukit/rtems/src/timerserver.c b/cpukit/rtems/src/timerserver.c new file mode 100644 index 0000000000..a92a828423 --- /dev/null +++ b/cpukit/rtems/src/timerserver.c @@ -0,0 +1,317 @@ +/* + * 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.rtems.com/license/LICENSE. + * + * $Id$ + */ + +#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/rtems/support.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; + +/* + * These variables keep track of the last time the Timer Server actually + * processed the chain. + */ + +Watchdog_Interval _Timer_Server_seconds_last_time; +Watchdog_Interval _Timer_Server_ticks_last_time; + +/* + * The timer used to control when the Timer Server wakes up to service + * "when" timers. + */ + +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( + uint32_t ignored +) +{ + /* + * 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; + + _Thread_Disable_dispatch(); + while(1) { + + /* + * Block until there is something to do. + */ + + _Thread_Set_state( _Timer_Server, STATES_DELAYING ); + _Timer_Server_reset_ticks_timer(); + _Timer_Server_reset_seconds_timer(); + _Thread_Enable_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(); + + /* + * 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(); + _Timer_Server_process_ticks_chain(); + _Timer_Server_process_seconds_chain(); + } + + return 0; /* unreached - only to remove warnings */ +} + +/*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: + * priority - timer server priority + * stack_size - stack size in bytes + * attribute_set - timer server attributes + * + * Output parameters: + * RTEMS_SUCCESSFUL - if successful + * error code - if unsuccessful + */ + + +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; + + /* + * Make sure the requested priority is valid. + */ + + _priority = priority; + if ( priority == RTEMS_TIMER_SERVER_DEFAULT_PRIORITY ) + _priority = 0; + else if ( !_RTEMS_tasks_Priority_is_valid( priority ) ) + return RTEMS_INVALID_PRIORITY; + + /* + * 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 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( + 0x4954454d, /* "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) { + _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) + ); + + /* + * 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_process_ticks_chain + * + * This routine is responsible for adjusting the list of task-based + * interval timers to reflect the passage of time. + * + * Input parameters: NONE + * + * Output parameters: NONE + */ + +void _Timer_Server_process_ticks_chain(void) +{ + 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( &_Timer_Ticks_chain, WATCHDOG_FORWARD, ticks ); +} + +/*PAGE + * + * _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. + * + * Input parameters: NONE + * + * Output parameters: NONE + */ + +void _Timer_Server_process_seconds_chain(void) +{ + 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( &_Timer_Seconds_chain, WATCHDOG_FORWARD, ticks ); + + } 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; +} |