///////////////////////////////////////////////////////////////////////////////////
// File     : irq_handler.c
// Date     : 01/04/2012
// Author   : alain greiner 
// Copyright (c) UPMC-LIP6
///////////////////////////////////////////////////////////////////////////////////
// The irq_handler.c and irq_handler.h files are part of the GIET-VM nano-kernel.
// They contain the code of the _irq_demux() function that access the XICU or
// ICU component (Interupt Controler Unit), and the various ISRs (Interrupt
// Service Routine) associated to the peripherals. 
///////////////////////////////////////////////////////////////////////////////////

#include <giet_config.h>
#include <irq_handler.h>
#include <sys_handler.h>
#include <ctx_handler.h>
#include <tim_driver.h>
#include <icu_driver.h>
#include <xcu_driver.h>
#include <tty_driver.h>
#include <ioc_driver.h>
#include <dma_driver.h>
#include<mapping_info.h>
#include <utils.h>

#if !defined( USE_XICU )
# error: You must define USE_XICU in the hard_config.h file
#endif

#if NB_TIM_CHANNELS
extern volatile unsigned char _user_timer_event[NB_CLUSTERS * NB_TIM_CHANNELS] ;
#endif

///////////////////////////////////////////////////////////////////////////////////
// This function uses the ICU or XICU component (Interrupt Controler Unit)
// to get the interrupt vector entry. There is one ICU or XICU component per
// cluster, and this component can support up to NB_PROCS_MAX output IRQs.
// It returns the highest priority active interrupt index (smaller
// indexes have the highest priority).
// Any value larger than 31 means "no active interrupt", and no ISR is executed.
//
// There is one interrupt vector per processor (stored in the scheduler associated
// to the processor. Each interrupt vector entry contains four bits fields:
// - isr_id     bits[7:0]   : defines the type of ISR to be executed.
// - type_id    bits[15:8]  : IRQ_TYPE_HWI / IRQ_TYPE_SWI / IRQ_TYPE_PTI
// - channel_id bits[30:16] : defines the channel for multi-channels peripherals.
// - valid      bit 31      : valid interrupt vector entry
// If the peripheral is replicated in clusters (TIMER or DMA), the channel_id is 
// a global index : channel_id = cluster_id * NB_CHANNELS_MAX + loc_id   
///////////////////////////////////////////////////////////////////////////////////
void _irq_demux() 
{
    unsigned int gpid       = _get_procid();
    unsigned int cluster_id = gpid / NB_PROCS_MAX;
    unsigned int local_id   = gpid % NB_PROCS_MAX;
    unsigned int irq_id;
    unsigned int ko;

    // get the highest priority active IRQ index 

#if USE_XICU
    ko = _xcu_get_index( cluster_id, local_id, &irq_id );
#else
    ko = _icu_get_index( cluster_id, local_id, &irq_id );
#endif

    if ( ko )
    {
        _tty_get_lock( 0 );
        _puts("\n[GIET ERROR] Wrong _icu_read in _irq_demux()\n");
        _tty_release_lock( 0 );
    }

    // do nothing if no interrupt active, or 
    if (irq_id < 32) 
    {
        static_scheduler_t* psched     = (static_scheduler_t*)_get_sched();
        unsigned int        entry      = psched->interrupt_vector[irq_id];
        unsigned int        isr_id     = (entry    ) & 0x000000FF;
        unsigned int        type_id    = (entry>> 8) & 0x000000FF;
        unsigned int        channel_id = (entry>>16) & 0x00007FFF;

        if(type_id == IRQ_TYPE_HWI)      // HWI
        {
            if      ( isr_id == ISR_SWITCH) _isr_switch(channel_id);
            else if ( isr_id == ISR_IOC   ) _isr_ioc();
            else if ( isr_id == ISR_TTY   ) _isr_tty(channel_id);
            else if ( isr_id == ISR_TIMER ) _isr_timer(channel_id);
            else if ( isr_id == ISR_WAKUP ) _isr_timer(channel_id);
            else                            _isr_default( irq_id, isr_id, type_id );
        }
        else if(type_id == IRQ_TYPE_PTI) // PTI
        {
            if      ( isr_id == ISR_SWITCH) _isr_switch(irq_id);
            else if ( isr_id == ISR_TIMER ) _isr_timer(irq_id);
            else                            _isr_default( irq_id, isr_id, type_id );
        }
        else if(type_id == IRQ_TYPE_SWI) // SWI
        {
            if      ( isr_id == ISR_WAKUP ) return;
            else                            _isr_default( irq_id, isr_id, type_id );
        }
    }
}

///////////////////////////////////////////////////////////////////////////////////
// The default ISR is called when no specific ISR has been installed in the
// interrupt vector. It simply displays an error message on kernel TTY[0].
///////////////////////////////////////////////////////////////////////////////////
void _isr_default( unsigned int irq_id,
                   unsigned int isr_id,
                   unsigned int type_id ) 
{
    _tty_get_lock( 0 );
    _puts("\n[GIET ERROR] Undefined ISR index = ");
    _putd( isr_id );
    if(type_id == IRQ_TYPE_HWI) _puts(" / type = HWI ");
    if(type_id == IRQ_TYPE_SWI) _puts(" / type = SWI ");
    if(type_id == IRQ_TYPE_PTI) _puts(" / type = PTI ");
    _puts(" / IRQ index = ");
    _putd( irq_id );
    _puts(" / processor = ");
    _putd( _get_procid() );
    _puts("\n");
    _tty_release_lock( 0 );
    _exit();
}


///////////////////////////////////////////////////////////////////////////////////
// This ISR is executed when a processor wakes up after a SWI interrup.
///////////////////////////////////////////////////////////////////////////////////
void _isr_wakup() 
{
    _tty_get_lock( 0 );
    _puts("\n  Processor ");
    _putd( _get_procid() );
    _puts(" wake up\n");
    _tty_release_lock( 0 );
}

///////////////////////////////////////////////////////////////////////////////////
// There is only one IOC controler shared by all tasks. 
// This ISR save the status, acknowledge the IRQ.
// and activates the task waiting on IO transfer.
//
// TODO the _set_task_slot access should be replaced by an atomic LL/SC
//      when the CTX_RUN bool will be replaced by a bit_vector. 
///////////////////////////////////////////////////////////////////////////////////
void _isr_ioc() 
{
    // save status in _ioc_status variable and reset IRQ 
    _ioc_status = _ioc_get_status(); 

    // reactivate task waiting on IOC
    unsigned int gpid = _ioc_gtid>>16;
    unsigned int ltid = _ioc_gtid & 0xFFFF;

    _set_task_slot( gpid,        // global processor index
                    ltid,        // local task index (on processor)
                    CTX_RUN_ID,  // CTX_RUN slot 
                    1 );         // running
}

///////////////////////////////////////////////////////////////////////////////////
// This ISR handles the IRQs generated by the "user" timers (the IRQs generated
// by the "system" timers should be handled by the _isr_switch().
// These timers are distributed in all clusters, and can be implemented
// in a vci_multi_timer component, or in a vci_xicu component.
// The timer_id argument is the user timer local index.
//     timer_globa_id = cluster_id*(NB_TIM_CHANNELS) + timer_id 
// The ISR acknowledges the IRQ and registers the event in the proper entry
// of the _timer_event[] array, and a log message is displayed on kernel terminal.
///////////////////////////////////////////////////////////////////////////////////
void _isr_timer(unsigned int timer_id) 
{
    // compute cluster_id 
    unsigned int cluster_id = _get_procid() / NB_PROCS_MAX;

    // aknowledge IRQ 
    if (_timer_reset_irq( cluster_id, timer_id)) 
    {
        _tty_get_lock( 0 );
        _puts("[GIET ERROR] illegal timer index detected by _isr_timer\n");
        _tty_release_lock( 0 );
        return;
    }

#if NB_TIM_CHANNELS
    // register the event
    unsigned int timer_global_id = cluster_id * NB_TIM_CHANNELS + timer_id;
    _user_timer_event[timer_global_id] = 1;
#endif

    // display a message on TTY 0 
    _tty_get_lock( 0 );
    _puts("\n[GIET] User Timer IRQ at cycle ");
    _putd(_get_proctime());
    _puts("\n - cluster_id = ");
    _putd(cluster_id);
    _puts("\n - timer_id   = ");
    _putd(timer_id);
    _puts("\n");
    _tty_release_lock( 0 );
}


///////////////////////////////////////////////////////////////////////////////////
// This ISR handles the IRQs generated by the multi_tty controler,
// signaling that a character is available.
// There is one single multi_tty component controling all TTYs, 
// and the tty_id argument is the global TTY index.
// There is one communication buffer _tty_buf[tty_id] per terminal.
// The sychronisation variable _tty_full[tty_id], is set by the ISR,
// and reset by the OS.
// A character is lost if the buffer is full when the ISR is executed.
///////////////////////////////////////////////////////////////////////////////////
void _isr_tty(unsigned int tty_id) 
{
    // read character and reset IRQ in one read access
    _tty_get_buf[tty_id] = _tty_read_data( tty_id ); 

    // signals character available 
    _tty_get_full[tty_id] = 1;
}


/////////////////////////////////////////////////////////////////////////////////////
// This ISR is in charge of context switch, and handle the IRQs generated by
// the "system" timers. 
// The IRQs can be generated by the MULTI_TIMER component or by the XICU component,
// that are distributed in all clusters.
// The ISR acknowledges the IRQ and calls the _ctx_switch() function.
/////////////////////////////////////////////////////////////////////////////////////
void _isr_switch( unsigned int timer_id) 
{
    // get cluster index 
    unsigned int cluster_id = _get_procid() / NB_PROCS_MAX;

    // acknowledge IRQ

#if USE_XICU
    if ( _xcu_timer_reset_irq( cluster_id, timer_id) ) 
    {
        _tty_get_lock( 0 );
        _puts("[GIET ERROR] illegal proc index detected by _isr_switch\n");
        _tty_release_lock( 0 );
        return;
    }
#else
    if (_timer_reset_irq(cluster_id, timer_id)) 
    {
        _tty_get_lock( 0 );
        _puts("[GIET ERROR] illegal proc index detected by _isr_switch\n");
        _tty_release_lock( 0 );
        return;
    }
#endif

    // performs the context switch
    _ctx_switch();
}


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