drv_api.c

eCos操作系统源码

//==========================================================================
//
//      drv_api.c
//
//      Driver API for non-kernel configurations
//
//==========================================================================
//####ECOSGPLCOPYRIGHTBEGIN####
// -------------------------------------------
// This file is part of eCos, the Embedded Configurable Operating System.
// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
//
// eCos is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 or (at your option) any later version.
//
// eCos is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with eCos; if not, write to the Free Software Foundation, Inc.,
// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
//
// As a special exception, if other files instantiate templates or use macros
// or inline functions from this file, or you compile this file and link it
// with other works to produce a work based on this file, this file does not
// by itself cause the resulting work to be covered by the GNU General Public
// License. However the source code for this file must still be made available
// in accordance with section (3) of the GNU General Public License.
//
// This exception does not invalidate any other reasons why a work based on
// this file might be covered by the GNU General Public License.
//
// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
// at http://sources.redhat.com/ecos/ecos-license/
// -------------------------------------------
//####ECOSGPLCOPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):   Nick Garnett
// Date:        1999-02-24
// Purpose:     Driver API for non-kernel configurations
// Description: These functions are used to support drivers when the kernel
//              is not present.
//              
//              
//
//####DESCRIPTIONEND####
//
//==========================================================================

#include <pkgconf/system.h>

#ifndef CYGPKG_KERNEL

#include <cyg/infra/cyg_type.h>
#include <cyg/infra/cyg_trac.h>
#include <cyg/infra/cyg_ass.h>

#include <pkgconf/hal.h>
#include <cyg/hal/drv_api.h>

#include <cyg/hal/hal_arch.h>
#include <cyg/hal/hal_intr.h>

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

static volatile cyg_int32 isr_disable_counter = 1;  // ISR disable counter

static CYG_INTERRUPT_STATE isr_disable_state;

volatile cyg_int32 dsr_disable_counter  // DSR disable counter
                      CYGBLD_ATTRIB_ASM_ALIAS( cyg_scheduler_sched_lock );

static cyg_interrupt* volatile dsr_list;        // List of pending DSRs

#ifdef CYGIMP_HAL_COMMON_INTERRUPTS_CHAIN

cyg_interrupt *chain_list[CYGNUM_HAL_ISR_COUNT];

#endif

//--------------------------------------------------------------------------
// DSR handling functions.
// post_dsr() places a DSR on the list of DSRs to be called.
// call_dsrs() calls the DSRs.

static void post_dsr( cyg_interrupt *intr )
{
    CYG_INTERRUPT_STATE old_intr;

    CYG_REPORT_FUNCTION();

    HAL_DISABLE_INTERRUPTS(old_intr);

    if( intr->dsr_count++ == 0 )
    {
        intr->next_dsr = dsr_list;
        dsr_list = intr;
    }

    HAL_RESTORE_INTERRUPTS(old_intr);

    CYG_REPORT_RETURN();    
}

static void call_dsrs(void)
{
    CYG_REPORT_FUNCTION();
    
    while( dsr_list != NULL )
    {
        cyg_interrupt *intr;
        cyg_int32 count;
        CYG_INTERRUPT_STATE old_intr;

        HAL_DISABLE_INTERRUPTS(old_intr);
        
        intr = dsr_list;
        dsr_list = intr->next_dsr;
        count = intr->dsr_count;
        intr->dsr_count = 0;
        
        HAL_RESTORE_INTERRUPTS(old_intr);

        intr->dsr( intr->vector, count, (CYG_ADDRWORD)intr->data );
    }

    CYG_REPORT_RETURN();
    
}

//--------------------------------------------------------------------------
// This is referenced from the HAL, although it does not actually get called.

externC void
cyg_interrupt_call_pending_DSRs(void)
{
    call_dsrs();
}

//--------------------------------------------------------------------------
// This is called from springboard ISRs in some HALs.

externC void
cyg_interrupt_post_dsr(CYG_ADDRWORD data)
{
  cyg_interrupt * intr = (cyg_interrupt *)data;
  post_dsr(intr);
}

//--------------------------------------------------------------------------
// Interrupt end function called from HAL VSR to tidy up. This is where
// DSRs will be called if necessary.

externC void
interrupt_end(
    cyg_uint32          isr_ret,
    cyg_interrupt       *intr,
    HAL_SavedRegisters  *regs
    )
{
    CYG_REPORT_FUNCTION();
    
#ifndef CYGIMP_HAL_COMMON_INTERRUPTS_CHAIN

    // Only do this if we are in a non-chained configuration.
    // If we are chained, then chain_isr will do the DSR
    // posting.
    
    if( isr_ret & CYG_ISR_CALL_DSR && intr != NULL ) post_dsr(intr);

#endif

    if( dsr_disable_counter == 0 ) call_dsrs();

    CYG_REPORT_RETURN();    
}

//--------------------------------------------------------------------------
// ISR for handling chained interrupts.

#ifdef CYGIMP_HAL_COMMON_INTERRUPTS_CHAIN

cyg_uint32 chain_isr(cyg_vector_t vector, CYG_ADDRWORD data)
{
    cyg_interrupt *p = *(cyg_interrupt **)data;
    register cyg_uint32 isr_ret = 0;
    register cyg_uint32 isr_chain_ret = 0;

    CYG_REPORT_FUNCTION();

    while( p != NULL )
    {
        if( p->vector == vector )
        {
            isr_ret = p->isr(vector, p->data);

            isr_chain_ret |= isr_ret;

            if( isr_ret & CYG_ISR_CALL_DSR ) post_dsr(p);

            if( isr_ret & CYG_ISR_HANDLED ) break;
        }

        p = p->next;
    }

#ifdef HAL_DEFAULT_ISR
    if( (isr_chain_ret & (CYG_ISR_CALL_DSR|CYG_ISR_HANDLED)) == 0 )
    {
        // If we finished the loop for some reason other than that an
        // ISR has handled the interrupt, call any default ISR to either
        // report the spurious interrupt, or do some other HAL level processing
        // such as GDB interrupt detection etc.

        HAL_DEFAULT_ISR( vector, 0 );
    }
#endif    

    CYG_REPORT_RETURN();
    
    return isr_ret & CYG_ISR_CALL_DSR;
}

#endif

//--------------------------------------------------------------------------
// ISR lock. This disables interrupts and keeps a count of the number
// times it has been called.

externC void cyg_drv_isr_lock()
{
    CYG_REPORT_FUNCTION();

    if( isr_disable_counter == 0 )
        HAL_DISABLE_INTERRUPTS(isr_disable_state);

    CYG_ASSERT( isr_disable_counter >= 0 , "Disable counter negative");
    
    isr_disable_counter++;
    
    CYG_REPORT_RETURN();    
}

//--------------------------------------------------------------------------
// Unlock ISRs. This decrements the count and re-enables interrupts if it
// goes zero.

externC void cyg_drv_isr_unlock()
{
    CYG_REPORT_FUNCTION();
        
    CYG_ASSERT( isr_disable_counter > 0 , "Disable counter not greater than zero");
    
    isr_disable_counter--;

    if ( isr_disable_counter == 0 )
    {
        HAL_RESTORE_INTERRUPTS(isr_disable_state);
    }

    CYG_REPORT_RETURN();
}

//--------------------------------------------------------------------------
// Lock DSR lock. Simply increment the counter.

externC void cyg_drv_dsr_lock()
{
    CYG_REPORT_FUNCTION();

    dsr_disable_counter++;

    CYG_REPORT_RETURN();
}

//--------------------------------------------------------------------------
// Unlock DSR lock. If the counter is about to go zero, call any pending
// DSRs and then zero the counter.

externC void cyg_drv_dsr_unlock()
{
    CYG_REPORT_FUNCTION();

    do
    {
        if( dsr_disable_counter == 1 )
        {
            call_dsrs();
        }

        HAL_REORDER_BARRIER();
        
        dsr_disable_counter = 0;

        HAL_REORDER_BARRIER();

        // Check that no DSRs have been posted between calling
        // call_dsrs() and zeroing dsr_disable_counter. If so,
        // loop back and call them.
        
        if( dsr_list != NULL )
        {
            dsr_disable_counter = 1;
            continue;
        }

        CYG_REPORT_RETURN();
        
        return;
        
    } while(1);

    CYG_FAIL( "Should not be executed" );
}

//--------------------------------------------------------------------------
// Initialize a mutex.

externC void cyg_drv_mutex_init( cyg_drv_mutex_t *mutex )
{
    CYG_REPORT_FUNCTION();
    
    mutex->lock = 0;

    CYG_REPORT_RETURN();    
}

//--------------------------------------------------------------------------
// Destroy a mutex.

externC void cyg_drv_mutex_destroy( cyg_drv_mutex_t *mutex )
{
    CYG_REPORT_FUNCTION();
    
    mutex->lock = -1;

    CYG_REPORT_RETURN();    
}

//--------------------------------------------------------------------------
// Lock a mutex. We check that we are not trying to lock a locked or
// destroyed mutex and if not, set it locked.

externC cyg_bool_t cyg_drv_mutex_lock( cyg_drv_mutex_t *mutex )
{
    CYG_REPORT_FUNCTION();
    
    CYG_ASSERT( mutex->lock == 0 , "Trying to lock locked mutex");

    mutex->lock = 1;

    CYG_REPORT_RETURN();

    return true;
}

//--------------------------------------------------------------------------
// Attempt to claim a mutex, and return if it cannot be.

externC cyg_bool_t cyg_drv_mutex_trylock( cyg_drv_mutex_t *mutex )
{
    cyg_bool_t result = true;
    
    CYG_REPORT_FUNCTION();

    if( mutex->lock == 1 ) result = false;

    mutex->lock = 1;
    
    CYG_REPORT_RETURN();

    return result;
}

//--------------------------------------------------------------------------
// Unlock a mutex. We check that the mutex is actually locked before doing
// this.

externC void cyg_drv_mutex_unlock( cyg_drv_mutex_t *mutex )
{
    CYG_REPORT_FUNCTION();

    CYG_ASSERT( mutex->lock == 1 , "Trying to unlock unlocked mutex");

    mutex->lock = 0;
    
    CYG_REPORT_RETURN();    
}
    
//--------------------------------------------------------------------------
// Release all threads waiting for the mutex.
// This is really for threads, so we do nothing here.

externC void cyg_drv_mutex_release( cyg_drv_mutex_t *mutex )
{
    CYG_REPORT_FUNCTION();


    
    CYG_REPORT_RETURN();    
}
    

//--------------------------------------------------------------------------
// Initialized a condition variable.

externC void cyg_drv_cond_init( cyg_drv_cond_t  *cond, cyg_drv_mutex_t *mutex )
{
    CYG_REPORT_FUNCTION();

    cond->wait = 0;
    cond->mutex = mutex;
    
    CYG_REPORT_RETURN();    
}
    

//--------------------------------------------------------------------------
// Destroy a condition variable.

externC void cyg_drv_cond_destroy( cyg_drv_cond_t  *cond )
{
    CYG_REPORT_FUNCTION();

    cond->wait = -1;
    cond->mutex = NULL;
    
    CYG_REPORT_RETURN();    
}
    
// -------------------------------------------------------------------------
// Wait for a condition variable to be signalled. We simply busy wait
// polling the condition variable's wait member until a DSR sets it to
// 0.  Note that the semantics of condition variables means that the
// wakeup only happens if there is a thread actually waiting on the CV
// when the signal is sent.

externC cyg_bool cyg_drv_cond_wait( cyg_drv_cond_t *cond )
{
    CYG_REPORT_FUNCTION();

    CYG_ASSERT( cond->mutex != NULL, "Uninitialized condition variable");
    CYG_ASSERT( cond->mutex->lock, "Mutex not locked");

    cyg_drv_dsr_lock();
    
    cond->wait = 1;
       
    while( cond->wait == 1 )
    {
        // While looping we call call_dsrs() to service any DSRs that
        // get posted. One of these will make the call to cond_signal
        // to break us out of this loop. If we do not have the DSR
        // lock claimed, then a race condition could occur and keep us
        // stuck here forever.
        
        call_dsrs();
    }

    cyg_drv_dsr_unlock();
    
    CYG_REPORT_RETURN();

    return true;
}

//--------------------------------------------------------------------------