emulate.cxx

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//==========================================================================
//
//      io/watchdog/emulate.cxx
//
//      Watchdog implementation emulation
//
//==========================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):   nickg
// Contributors:        nickg
// Date:        1998-07-29
// Purpose:     Watchdog class implementation
// Description: Contains an implementation of the Watchdog class for use
//              when there is no hardware watchdog timer. Instead it is
//              emulated using an Alarm object.
//
//####DESCRIPTIONEND####
//
//==========================================================================

#include <pkgconf/watchdog.h>           // watchdog configuration file
#include <pkgconf/kernel.h>             // Kernel config

#include <cyg/kernel/ktypes.h>          // base kernel types
#include <cyg/infra/cyg_trac.h>         // tracing macros
#include <cyg/infra/cyg_ass.h>          // assertion macros
#include <cyg/kernel/instrmnt.h>        // instrumentation

#include <cyg/kernel/clock.hxx>         // clock and alarm
#include <cyg/kernel/sched.hxx>         // scheduler

#include <cyg/io/watchdog.hxx>          // watchdog API

#include <cyg/kernel/sched.inl>         // scheduler inlines

// -------------------------------------------------------------------------
// Forward definitions

static cyg_alarm_fn    watchdog_alarm;

// -------------------------------------------------------------------------
// Statics

static Cyg_Alarm alarm( Cyg_Clock::real_time_clock, watchdog_alarm, 0 );

// One second's worth of ticks.
static cyg_tick_count one_sec;

// -------------------------------------------------------------------------
// HW init

void
Cyg_Watchdog::init_hw(void)
{
    CYG_REPORT_FUNCTION();

    Cyg_Clock::cyg_resolution res = Cyg_Clock::real_time_clock->get_resolution();

    one_sec             = ( res.divisor * 1000000000LL ) / res.dividend ;

    resolution          = 1000000000LL;

    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// Start the watchdog running.

void Cyg_Watchdog::start()
{
    CYG_REPORT_FUNCTION();
    
    Cyg_Clock::cyg_resolution res = Cyg_Clock::real_time_clock->get_resolution();

    // Set alarm to a one second single-shot trigger
    alarm.initialize( Cyg_Clock::real_time_clock->current_value() + one_sec, 0 );

    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// Reset watchdog timer. This needs to be called regularly to prevent
// the watchdog firing.

void Cyg_Watchdog::reset()
{    
    CYG_REPORT_FUNCTION();
    
    Cyg_Clock::cyg_resolution res = Cyg_Clock::real_time_clock->get_resolution();

    Cyg_Scheduler::lock();
    
    // Set alarm to a one second single-shot trigger
    alarm.initialize( Cyg_Clock::real_time_clock->current_value() + one_sec, 0 );    

    Cyg_Scheduler::unlock();    

    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// Alarm function

void watchdog_alarm( Cyg_Alarm *a, CYG_ADDRWORD data)
{
    CYG_REPORT_FUNCTION();
    
    // Disable alarm just in case
    alarm.disable();

    Cyg_Watchdog::watchdog.trigger();
}

// -------------------------------------------------------------------------
// EOF watchdog/emulate.cxx