///////////////////////////////////////////////////////////////////////////////////
// File      : bdv_driver.c
// Date      : 23/05/2013
// Author    : alain greiner
// Maintainer: cesar fuguet
// Copyright (c) UPMC-LIP6
///////////////////////////////////////////////////////////////////////////////////
// Implementation notes:
// 1. In order to share code, the two _bdv_read() and _bdv_write() functions
//    call the same _bdv_access() function.
// 2. All accesses to BDV registers are done by the two
//    _bdv_set_register() and _bdv_get_register() low-level functions,
//    that are handling virtual / physical extended addressing.
///////////////////////////////////////////////////////////////////////////////////

#include <giet_config.h>
#include <hard_config.h>
#include <bdv_driver.h>
#include <xcu_driver.h>
#include <ioc_driver.h>
#include <utils.h>
#include <tty0.h>
#include <ctx_handler.h>

///////////////////////////////////////////////////////////////////////////////
// BDV global variables
///////////////////////////////////////////////////////////////////////////////

spin_lock_t  _bdv_lock __attribute__((aligned(64)));
unsigned int _bdv_status;
unsigned int _bdv_gtid;

///////////////////////////////////////////////////////////////////////////////
// This low_level function returns the value contained in register (index).
///////////////////////////////////////////////////////////////////////////////
unsigned int _bdv_get_register( unsigned int index )
{
    unsigned int* vaddr = (unsigned int*)SEG_IOC_BASE + index;
    return _io_extended_read( vaddr );
}

///////////////////////////////////////////////////////////////////////////////
// This low-level function set a new value in register (index).
///////////////////////////////////////////////////////////////////////////////
void _bdv_set_register( unsigned int index,
                        unsigned int value ) 
{
    unsigned int* vaddr = (unsigned int*)SEG_IOC_BASE + index;
    _io_extended_write( vaddr, value );
}

///////////////////////////////////////////////////////////////////////////////
// This function transfer data between a memory buffer and the block device.
// The buffer lentgth is (count*block_size) bytes.
// Arguments are:
// - to_mem     : from external storage to memory when non 0.
// - mode       : BOOT / KERNEL / USER
// - lba        : first block index on the external storage.
// - buf_paddr  : physical base address of the memory buffer.
// - count      : number of blocks to be transfered.
// Returns 0 if success, > 0 if error.
///////////////////////////////////////////////////////////////////////////////
static unsigned int _bdv_access( unsigned int       to_mem,
                                 unsigned int       mode,
                                 unsigned int       lba,
                                 unsigned long long buf_paddr,
                                 unsigned int       count) 
{
    unsigned int procid  = _get_procid();
    unsigned int x       = procid >> (Y_WIDTH + P_WIDTH);
    unsigned int y       = (procid >> P_WIDTH) & ((1<<Y_WIDTH) - 1);
    unsigned int p       = procid & ((1<<P_WIDTH)-1);

#if GIET_DEBUG_IOC_DRIVER
_puts("\n[BDV DEBUG] _bdv_access() : P[");
_putd( x );
_puts(",");
_putd( y );
_puts(",");
_putd( p );
_puts("] enters at cycle ");
_putd( _get_proctime() );
_puts("\n - to_mem  = ");
_putd( to_mem );
_puts("\n - mode    = ");
_putd( mode );
_puts("\n - paddr   = ");
_putl( buf_paddr );
_puts("\n - sectors = ");
_putd( count );
_puts("\n - lba     = ");
_putx( lba );
_puts("\n");
#endif

    unsigned int       error = 0;

    // get the lock protecting BDV
    _spin_lock_acquire( &_bdv_lock );

#if GIET_DEBUG_IOC_DRIVER
_puts("\n[BDV DEBUG] _bdv_access() : P[");
_putd( x );
_puts(",");
_putd( y );
_puts(",");
_putd( p );
_puts("] get _bdv_lock at cycle ");
_putd( _get_proctime() );
_puts("\n");
#endif

    // set device registers
    _bdv_set_register( BLOCK_DEVICE_BUFFER    , (unsigned int)buf_paddr );
    _bdv_set_register( BLOCK_DEVICE_BUFFER_EXT, (unsigned int)(buf_paddr>>32) );
    _bdv_set_register( BLOCK_DEVICE_COUNT     , count );
    _bdv_set_register( BLOCK_DEVICE_LBA       , lba );

    // In BOOT mode, we launch transfer, and poll the BDV_STATUS 
    // register because IRQs are masked.
    if ( mode == IOC_BOOT_MODE ) 
    {
        // Launch transfert
        if (to_mem == 0) _bdv_set_register( BLOCK_DEVICE_OP, BLOCK_DEVICE_WRITE );
        else             _bdv_set_register( BLOCK_DEVICE_OP, BLOCK_DEVICE_READ );

#if GIET_DEBUG_IOC_DRIVER
_puts("\n[BDV DEBUG] _bdv_access() : P[");
_putd( x );
_puts(",");
_putd( y );
_puts(",");
_putd( p );
_puts("] launch transfer in polling mode\n");
#endif
        unsigned int status;
        do
        {
            status = _bdv_get_register( BLOCK_DEVICE_STATUS );

#if GIET_DEBUG_IOC_DRIVER
_puts("\n[BDV DEBUG] _bdv_access() : P[");
_putd( x );
_puts(",");
_putd( y );
_puts(",");
_putd( p );
_puts("] wait on BDV_STATUS register ...\n");
#endif
        }
        while( (status != BLOCK_DEVICE_READ_SUCCESS)  &&
               (status != BLOCK_DEVICE_READ_ERROR)    &&
               (status != BLOCK_DEVICE_WRITE_SUCCESS) &&
               (status != BLOCK_DEVICE_WRITE_ERROR)   );      // busy waiting

        // analyse status
        error = ( (status == BLOCK_DEVICE_READ_ERROR) ||
                  (status == BLOCK_DEVICE_WRITE_ERROR) );

        // release lock
        _spin_lock_release( &_bdv_lock );      
    }
    // in USER or KERNEL mode, we deschedule the task.
    // When the task is rescheduled, we check the _bdv_status variable, 
    // and release the lock.
    // We need a critical section, because we must reset the RUN bit
	// before to launch the transfer, and we don't want to be descheduled
	// between these two operations. 
    else
    {
        unsigned int save_sr;
        unsigned int ltid = _get_current_task_id();

        // activates BDV interrupts
        _bdv_set_register( BLOCK_DEVICE_IRQ_ENABLE, 1 );

        // set the _bdv_status variable
        _bdv_status = BLOCK_DEVICE_BUSY;

        // enters critical section
        _it_disable( &save_sr ); 

        // set _bdv_gtid and reset runnable 
        _bdv_gtid = (procid<<16) + ltid;
        _set_task_slot( x, y, p, ltid, CTX_RUN_ID, 0 );  
        
        // launch transfer
        if (to_mem == 0) _bdv_set_register( BLOCK_DEVICE_OP, BLOCK_DEVICE_WRITE );
        else             _bdv_set_register( BLOCK_DEVICE_OP, BLOCK_DEVICE_READ  );

#if GIET_DEBUG_IOC_DRIVER
_puts("\n[BDV DEBUG] _bdv_access() : P[");
_putd( x );
_puts(",");
_putd( y );
_puts(",");
_putd( p );
_puts("] launch transfer in nterrupt mode\n");
#endif

        // deschedule task
        _ctx_switch();                      

#if GIET_DEBUG_IOC_DRIVER
_puts("\n[BDV DEBUG] _bdv_access() : P[");
_putd( x );
_puts(",");
_putd( y );
_puts(",");
_putd( p );
_puts("] resume execution after descheduling\n");
#endif
        // restore SR
        _it_restore( &save_sr );

        // analyse status
        error = ( (_bdv_status == BLOCK_DEVICE_READ_ERROR) ||
                  (_bdv_status == BLOCK_DEVICE_WRITE_ERROR) );

        // reset _bdv_status and release lock
        _bdv_status = BLOCK_DEVICE_IDLE; 
        _spin_lock_release( &_bdv_lock );      
    }

#if GIET_DEBUG_IOC_DRIVER
_puts("\n[BDV DEBUG] _bdv_access() : P[");
_putd( x );
_puts(",");
_putd( y );
_puts(",");
_putd( p );
_puts("] exit at cycle ");
_putd( _get_proctime() );
_puts(" / error = ");
_putd( error );
_puts("\n");
#endif

    return error;
} // end _bdv_access()

///////////////////////////////////////////////////////////////////////////////
//      External functions
///////////////////////////////////////////////////////////////////////////////

////////////////////////
unsigned int _bdv_init()
{
    if ( _bdv_get_register( BLOCK_DEVICE_BLOCK_SIZE ) != 512 )
    {
        _puts("\n[GIET ERROR] in _bdv_init() : block size must be 512 bytes\n");
        return 1; 
    }

    _bdv_set_register( BLOCK_DEVICE_IRQ_ENABLE, 0 );
    return 0;
}

////////////////////////////////////////////////
unsigned int _bdv_read( unsigned int       mode,  
                        unsigned int       lba, 
                        unsigned long long buffer, 
                        unsigned int       count) 
{
    return _bdv_access( 1,        // read access
                        mode,  
                        lba,
                        buffer,
                        count );
}

/////////////////////////////////////////////////
unsigned int _bdv_write( unsigned int       mode,  
                         unsigned int       lba, 
                         unsigned long long buffer, 
                         unsigned int       count ) 
{
    return _bdv_access( 0,        // write access
                        mode,  
                        lba,
                        buffer,
                        count );
}

//////////////////////////////
unsigned int _bdv_get_status()
{
    return _bdv_get_register( BLOCK_DEVICE_STATUS );
}

//////////////////////////////////
unsigned int _bdv_get_block_size()
{
    return _bdv_get_register( BLOCK_DEVICE_BLOCK_SIZE );
}

/////////////////////////////////////
void _bdv_isr( unsigned int irq_type,   // HWI / WTI
               unsigned int irq_id,     // index returned by ICU
               unsigned int channel )   // unused 
{
    // get BDV status (and reset IRQ)
    unsigned int status =  _bdv_get_register( BLOCK_DEVICE_STATUS ); 

    // check status: does nothing if IDLE or BUSY
    if ( (status == BLOCK_DEVICE_IDLE) ||
         (status == BLOCK_DEVICE_BUSY) )   return;
 
    // save status in kernel buffer _bdv_status
    _bdv_status = status; 

    // identify task waiting on BDV
    unsigned int remote_procid  = _bdv_gtid>>16;
    unsigned int ltid           = _bdv_gtid & 0xFFFF;
    unsigned int remote_cluster = remote_procid >> P_WIDTH;
    unsigned int remote_x       = remote_cluster >> Y_WIDTH;
    unsigned int remote_y       = remote_cluster & ((1<<Y_WIDTH)-1);
    unsigned int remote_p       = remote_procid & ((1<<P_WIDTH)-1);

    // re-activates sleeping task
    _set_task_slot( remote_x,
                    remote_y,
                    remote_p,
                    ltid,        
                    CTX_RUN_ID,  // CTX_RUN slot 
                    1 );         // running

    // requires a context switch for remote processor running the waiting task 
    _xcu_send_wti( remote_cluster,   
                   remote_p, 
                   0 );          // don't force context switch if not idle

#if GIET_DEBUG_IRQS  // we don't take the TTY lock to avoid deadlock
unsigned int procid  = _get_procid();
unsigned int x       = procid >> (Y_WIDTH + P_WIDTH);
unsigned int y       = (procid >> P_WIDTH) & ((1<<Y_WIDTH)-1);
unsigned int p       = procid & ((1<<P_WIDTH)-1);

_puts("\n[IRQS DEBUG] Processor[");
_putd(x );
_puts(",");
_putd(y );
_puts(",");
_putd(p );
_puts("] enters _bdv_isr() at cycle ");
_putd(_get_proctime() );
_puts("\n  for task ");
_putd(ltid );
_puts(" running on processor[");
_putd(remote_x );
_puts(",");
_putd(remore_y );
_puts(",");
_putd(remote_p );
_puts(" / bdv status = ");
_putx(_bdv_status );
_puts("\n");
#endif

}


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