source: soft/giet_vm/giet_drivers/dma_driver.c @ 258

///////////////////////////////////////////////////////////////////////////////////
// File     : dma_driver.c
// Date     : 23/11/2013
// Author   : alain greiner
// Copyright (c) UPMC-LIP6
///////////////////////////////////////////////////////////////////////////////////
// The dma_driver.c and dma_driver.h files are part ot the GIET-VM nano-kernel.
// This driver supports the SoCLib vci_multi_dma component.
// 
// It can exist several DMA controlers in the architecture (one per cluster),
// and each controller can contain several channels.
// 
// There is  (NB_CLUSTERS * NB_DMA_CHANNELS) channels, indexed by a global index:
//        dma_id = cluster_id * NB_DMA_CHANNELS + loc_id
//
// A DMA channel is a private ressource allocated to a given processor.
// It is exclusively used by the kernet to speedup data transfers, and
// there is no lock protecting exclusive access to the channel.
// As the kernel uses a polling policy on the DMA_STATUS register to detect
// transfer completion, the DMA IRQ is not used, and there is no DMA_ISR.
////////////////////////////////////////////////////////////////////////////////////
// The virtual base address of the segment associated to a channel is:
//
//    seg_dma_base + cluster_id * vseg_cluster_increment + DMA_SPAN * channel_id
//
////////////////////////////////////////////////////////////////////////////////////

#include <giet_config.h>
#include <dma_driver.h>
#include <utils.h>
#include <tty_driver.h>
#include <vmem.h>

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

#if (NB_CLUSTERS > 256)
# error: NB_CLUSTERS cannot be larger than 256!
#endif

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

#if (NB_PROCS_MAX > 8)
# error: NB_PROCS_MAX cannot be larger than 8!
#endif

#if (NB_DMA_CHANNELS > 8)
# error: NB_DMA_CHANNELS cannot be larger than 8!
#endif

extern unsigned int _ptabs_vaddr[];

//////////////////////////////////////////////////////////////////////////////////
// AS the GIET-VM uses a polling policy to detect transfer completion,
// The DMA component initialisation must disable interrupts.
// This function disables interrupts for one DMA channel in one cluster.
// Returns 0 if success, returns > 0 if error.
//////////////////////////////////////////////////////////////////////////////////
unsigned int _dma_init( unsigned int cluster_id,
                        unsigned int channel_id )
{
#if NB_DMA_CHANNELS > 0
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)      return 1;
    if (channel_id >= NB_DMA_CHANNELS)  return 1; 

    // compute DMA base address
    unsigned int* dma_address = (unsigned int*) ((unsigned int)&seg_dma_base + 
                                (cluster_id * (unsigned int)&vseg_cluster_increment));

    // disable interrupt for selected channel
    dma_address[channel_id * DMA_SPAN + DMA_IRQ_DISABLE] = 1;            
    return 0;
#else
    return 1;
#endif
}

//////////////////////////////////////////////////////////////////////////////////
// This function re-initialises one DMA channel in one cluster after a transfer
// completion. It actually forces the channel to return in iDLE state.
//////////////////////////////////////////////////////////////////////////////////
unsigned int _dma_reset( unsigned int cluster_id, 
                         unsigned int channel_id ) 
{
#if NB_DMA_CHANNELS > 0
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)      return 1;
    if (channel_id >= NB_DMA_CHANNELS)  return 1; 

    // compute DMA base address
    unsigned int* dma_address = (unsigned int*) ((unsigned int)&seg_dma_base + 
                                (cluster_id * (unsigned int)&vseg_cluster_increment));

    // reset selected channel
    dma_address[channel_id * DMA_SPAN + DMA_RESET] = 0;            
    return 0;
#else
    return 1;
#endif
}

//////////////////////////////////////////////////////////////////////////////////
// This function returns the status of a DMA channel in a given cluster
//////////////////////////////////////////////////////////////////////////////////
unsigned int _dma_get_status( unsigned int cluster_id, 
                              unsigned int channel_id ) 
{
#if NB_DMA_CHANNELS > 0
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)      return 1;
    if (channel_id >= NB_DMA_CHANNELS)  return 1;

    // compute DMA base address
    unsigned int * dma_address = (unsigned int *) ((unsigned int)&seg_dma_base + 
                                 (cluster_id * (unsigned int)&vseg_cluster_increment));

    // get selected channel status
    return dma_address[channel_id * DMA_SPAN + DMA_LEN];
#else
    return DMA_ERROR;
#endif
}

//////////////////////////////////////////////////////////////////////////////////
// This function sets the physical address (including 64 bits extension)
// for the source and destination buffers in a DMA channel in a given cluster
// and sets the transfer size to lauch the transfer.
//////////////////////////////////////////////////////////////////////////////////
unsigned int _dma_start_transfer( unsigned int       cluster_id,
                                  unsigned int       channel_id,
                                  unsigned long long dst_paddr,   // physical address
                                  unsigned long long src_paddr,   // physical address
                                  unsigned int       size )       // bytes
{
#if NB_DMA_CHANNELS > 0
    // parameters checking 
    if (cluster_id >= NB_CLUSTERS)      return 1;
    if (channel_id >= NB_DMA_CHANNELS)  return 1;

    // compute DMA base address
    unsigned int * dma_address = (unsigned int *) ((unsigned int)&seg_dma_base + 
                                 (cluster_id * (unsigned int)&vseg_cluster_increment));

    // selected channel configuration and lauching
    dma_address[channel_id * DMA_SPAN + DMA_SRC]     = (unsigned int)(src_paddr);
    dma_address[channel_id * DMA_SPAN + DMA_SRC_EXT] = (unsigned int)(src_paddr>>32);
    dma_address[channel_id * DMA_SPAN + DMA_DST]     = (unsigned int)(dst_paddr);
    dma_address[channel_id * DMA_SPAN + DMA_DST_EXT] = (unsigned int)(dst_paddr>>32);
    dma_address[channel_id * DMA_SPAN + DMA_LEN]     = (unsigned int)size;
    return 0;
#else
    return 1;
#endif
}
///////////////////////////////////////////////////////////////////////////////////
// This function copies a source memory buffer to a destnation memory buffer, 
// using the distributed DMA. As it makes virtual to physical address translation, 
// the MMU should be activated. As there is one DMA channel per processor, 
// the DMA cluster and channel indexes are obtained from the processor index.
// The source and destination buffers base addresses must be word aligned, 
// and the buffer's size must be multiple of 4.
// In case of error (buffer unmapped, unaligned, or DMA_STATUS error), an error 
// message is displayed on TTY0, and the system crash.
///////////////////////////////////////////////////////////////////////////////////
// Note: this blocking function is supposed to be used by the kernel only, 
// and uses a polling policy on DMA_STATUS register to detect completion.
// Therefore, the DMA_IRQ is NOT used.
///////////////////////////////////////////////////////////////////////////////////
inline void  _dma_copy( unsigned int vspace_id, // vspace index for V2P
                        void*        dest,      // dest buffer vbase
                        const void*  source,    // source buffer vbase
                        unsigned int size )     // bytes
{
#if NB_DMA_CHANNELS > 0

    unsigned int procid    = _get_procid();
    unsigned int cluster_id = procid/NB_PROCS_MAX;
    unsigned int channel_id = procid%NB_PROCS_MAX;

    unsigned int ko;
    unsigned int ppn;
    unsigned int flags;

#if GIET_DEBUG_DMA_DRIVER
_tty_get_lock( 0 );
_puts("\n[DMA DEBUG] Enter _dma_copy() at cycle ");
_putd( _get_proctime() );
_puts("\n - vspace_id  = ");
_putx( vspace_id );
_puts("\n - cluster_id = ");
_putx( cluster_id );
_puts("\n - channel_id = ");
_putx( channel_id );
_puts("\n - dest       = ");
_putx( (unsigned int)dest );
_puts("\n - source     = ");
_putx( (unsigned int)source );
_puts("\n - bytes      = ");
_putd( size );
_tty_release_lock( 0 );
#endif

    // checking alignment constraints
    if ( (((unsigned int)dest) & 0x3)   ||
         (((unsigned int)source) & 0x3) ||
         (size & 0x3) )
    {
        _tty_get_lock( 0 );
        _puts("\n[GIET ERROR] in _dma_copy() : buffer unaligned\n");
        _tty_release_lock( 0 );
        _exit();
    }

    // get vspace 0 page table pointer 
    unsigned int pt =  _ptabs_vaddr[vspace_id];

    // get source buffer physical addresse
    ko = _v2p_translate( (page_table_t*)pt,              // page table pointer
                         ((unsigned int)source)>>12,     // vpn 
                         &ppn,                           // ppn
                         &flags );                       // flags
    if ( ko ) 
    {
        _tty_get_lock( 0 );
        _puts("\n[GIET ERROR] in _dma_copy() : source buffer unmapped\n");
        _tty_release_lock( 0 );
        _exit();
    }
    unsigned long long src_paddr = (((unsigned long long)ppn) << 12) | 
                                   ((unsigned int)source & 0x00000FFF);

    // get dest buffer physical addresse
    ko = _v2p_translate( (page_table_t*)pt,              // page table pointer
                         ((unsigned int)dest)>>12,       // vpn 
                         &ppn,                           // ppn
                         &flags );                       // flags
    if ( ko ) 
    {
        _tty_get_lock( 0 );
        _puts("\n[GIET ERROR] in _dma_copy() : dest buffer unmapped\n");
        _tty_release_lock( 0 );
        _exit();
    }
    unsigned long long dst_paddr = (((unsigned long long)ppn) << 12) | 
                                   ((unsigned int)dest & 0x00000FFF);

#if GIET_DEBUG_DMA_DRIVER
_tty_get_lock( 0 );
_puts("\n - src_paddr  = ");
_putl( src_paddr );
_puts("\n - dst_paddr  = ");
_putl( dst_paddr );
_puts("\n");
_tty_release_lock( 0 );
#endif

    // invalidate L1 cache if no hardware cache coherence
    if ( GIET_NO_HARD_CC ) _dcache_buf_invalidate( dest, size );

    // dma channel configuration & lauching
    ko = _dma_start_transfer(  cluster_id, channel_id, dst_paddr, src_paddr, size ); 
    if ( ko ) 
    {
        _tty_get_lock( 0 );
        _puts("\n[GIET ERROR] in _dma_copy() : cannot start transfer\n");
        _tty_release_lock( 0 );
        _exit();
    }

    // scan dma channel status 
    unsigned int status = _dma_get_status( cluster_id, channel_id );
    while( (status != DMA_SUCCESS) && 
           (status != DMA_READ_ERROR) &&
           (status != DMA_WRITE_ERROR) )
    {
        status = _dma_get_status( cluster_id, channel_id );

#if GIET_DEBUG_DMA_DRIVER
_tty_get_lock( 0 );
_puts("\n[DMA DEBUG] _dma_copy() : ... waiting on DMA_STATUS register ...\n");
_tty_release_lock( 0 );
#endif

    }
    
    // analyse status
    if( status != DMA_SUCCESS )
    {
        _tty_get_lock( 0 );
        _puts("\n[GIET ERROR] in _dma_copy() : DMA_STATUS error = ");
        _putd( status );
        _puts("\n");
        _tty_release_lock( 0 );
        _exit();
    }
    // reset dma channel
    _dma_reset( cluster_id, channel_id );

#if GIET_DEBUG_DMA_DRIVER
_tty_get_lock( 0 );
_puts("\n[DMA DEBUG] _dma_copy() completed at cycle ");
_putd( _get_proctime() );
_puts("\n");
_tty_release_lock( 0 );
#endif

#else // NB_DMA_CHANNELS == 0
    _tty_get_lock( 0 );
    _puts("\n[GIET ERROR] in _dma_copy() : NB_DMA_CHANNELS = 0 !\n");
    _tty_release_lock( 0 );
    _exit();
#endif
} // end _dma_copy




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