/*
* 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/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;
/*
* 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;
}
}
