///////////////////////////////////////////////////////////////////////////////////
// File      : bdv_driver.c
// Date      : 23/05/2013
// Author    : alain greiner
// Maintainer: cesar fuguet
// Copyright (c) UPMC-LIP6
///////////////////////////////////////////////////////////////////////////////////
// The bdv_driver.c and bdv_driver.h files are part ot the GIET-VM kernel.
// This driver supports the SocLib vci_block_device component, that is
// a single channel, block oriented, external storage contrôler.
//
// The _bdv_read() and _bdv_write() functions are always blocking.
// They can be called in 3 modes:
//
// - In BOOT mode, these functions use a polling policy on the BDV STATUS 
//   register to detect transfer completion, as interrupts are not activated. 
//   This mode is used by the boot code to load the map.bin file into memory
//   (before MMU activation), or to load the .elf files (after MMU activation). 
//
// - In KERNEL mode, these functions use a descheduling strategy:
//   The ISR executed when transfer completes should restart the calling task.
//   There is no checking of user access right to the memory buffer. 
//   This mode must be used, for an "open" system call.
//
// - In USER mode, these functions use a descheduling strategy:
//   The ISR executed when transfer completes should restart the calling task, 
//   The user access right to the memory buffer must be checked.
//   This mode must be used for a "read/write" system call.
//
// As the BDV component can be used by several programs running in parallel,
// the _bdv_lock variable guaranties exclusive access to the device.  The
// _bdv_read() and _bdv_write() functions use atomic LL/SC to get the lock.
//
// Finally, the memory buffer must fulfill the following conditions:
// - The buffer must be word aligned, 
// - The buffer must be mapped in user space for an user access, 
// - The buffer must be writable in case of (to_mem) access,
// - The total number of physical pages occupied by the user buffer cannot
//   be larger than 512 pages if the IOMMU is activated,
// - All physical pages occupied by the user buffer must be contiguous
//   if the IOMMU is not activated.
// An error code is returned if these conditions are not verified.
//
// The "seg_ioc_base" must be defined in giet_vsegs.ld file.
///////////////////////////////////////////////////////////////////////////////////
// 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 <bdv_driver.h>
#include <xcu_driver.h>
#include <ioc_driver.h>
#include <utils.h>
#include <tty_driver.h>
#include <ctx_handler.h>

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

#define in_unckdata __attribute__((section (".unckdata")))

in_unckdata unsigned int          _bdv_lock = 0;
in_unckdata volatile unsigned int _bdv_status = 0;
in_unckdata volatile 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) 
{

#if GIET_DEBUG_BDV_DRIVER
unsigned int procid  = _get_procid();
unsigned int cxy     = procid / NB_PROCS_MAX;
unsigned int lpid    = procid % NB_PROCS_MAX;
unsigned int x       = cxy >> Y_WIDTH;
unsigned int y       = cxy & ((1<<Y_WIDTH) - 1);

_printf("\n[BDV DEBUG] Processor[%d,%d,%d] enters _bdv_access() at cycle %d\n"
        " - mode    = %d\n"
        " - paddr   = %l\n"
        " - sectors = %x\n"
        " - lba     = %x\n",
        x, y, lpid, _get_proctime(), mode, buf_paddr, count, lba );
#endif

    unsigned int       error = 0;

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

    // 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 );

        unsigned int status;
        do
        {
            status = _bdv_get_register( BLOCK_DEVICE_STATUS );

#if GIET_DEBUG_BDV_DRIVER
_printf("\n[BDV DEBUG] _bdv_access() : ... waiting 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
        _release_lock(&_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();
        unsigned int gpid = _get_procid();

        // 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 = (gpid<<16) + ltid;
        _set_task_slot( gpid, 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  );

        // deschedule task
        _ctx_switch();                      

        // 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; 
        _release_lock(&_bdv_lock);      
    }

#if GIET_DEBUG_BDV_DRIVER
_printf("\n[BDV DEBUG] Processor[%d,%d,%d] exit _bdv_access() at cycle %d\n",
        x, y, lpid, _get_proctime() );
#endif

    return error;
} // end _bdv_access()

///////////////////////////////////////////////////////////////////////////////
// This function cheks block size, and desactivates the interrupts.
// Return 0 for success, > 0 if error
///////////////////////////////////////////////////////////////////////////////
unsigned int _bdv_init()
{
    if ( _bdv_get_register( BLOCK_DEVICE_BLOCK_SIZE ) != 512 )
    {
        _printf("\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;
}

///////////////////////////////////////////////////////////////////////////////
// Transfer data from the block device to a memory buffer. 
// - mode     : BOOT / KERNEL / USER
// - lba      : first block index on the block device
// - buffer   : base address of the memory buffer (must be word aligned)
// - count    : number of blocks to be transfered.
// Returns 0 if success, > 0 if error.
///////////////////////////////////////////////////////////////////////////////
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 );
}

///////////////////////////////////////////////////////////////////////////////
// Transfer data from a memory buffer to the block device. 
// - mode     : BOOT / KERNEL / USER
// - lba      : first block index on the block device
// - buffer   : base address of the memory buffer (must be word aligned)
// - count    : number of blocks to be transfered.
// Returns 0 if success, > 0 if error.
///////////////////////////////////////////////////////////////////////////////
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 );
}

///////////////////////////////////////////////////////////////////////////////
// Returns device status.
///////////////////////////////////////////////////////////////////////////////
unsigned int _bdv_get_status()
{
    return _bdv_get_register( BLOCK_DEVICE_STATUS );
}

///////////////////////////////////////////////////////////////////////////////
// Returns block size.
///////////////////////////////////////////////////////////////////////////////
unsigned int _bdv_get_block_size()
{
    return _bdv_get_register( BLOCK_DEVICE_BLOCK_SIZE );
}

///////////////////////////////////////////////////////////////////////////////////
// This ISR save the status, acknowledge the IRQ,
// and activates the task waiting on IO transfer.
// It can be an HWI or a SWI.
//
// 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 _bdv_isr( unsigned int irq_type,   // HWI / WTI
               unsigned int irq_id,     // index returned by ICU
               unsigned int channel )   // unused 
{
    unsigned int procid     = _get_procid();
    unsigned int cluster_xy = procid / NB_PROCS_MAX;
    unsigned int lpid       = procid % NB_PROCS_MAX;

    // acknowledge WTI in local XCU if required 
    unsigned int value;
    if ( irq_type == IRQ_TYPE_WTI ) _xcu_get_wti_value( cluster_xy, irq_id, &value );

    // save status in _bdv_status variable and reset IRQ
    _bdv_status = _bdv_get_register( BLOCK_DEVICE_STATUS ); 

    // identify task waiting on BDV
    unsigned int rprocid    = _bdv_gtid>>16;
    unsigned int ltid       = _bdv_gtid & 0xFFFF;
    unsigned int remote_xy  = rprocid / NB_PROCS_MAX;

#if GIET_DEBUG_IRQS  // we don't take the TTY lock to avoid deadlock
unsigned int x              = cluster_xy >> Y_WIDTH;
unsigned int y              = cluster_xy & ((1<<Y_WIDTH)-1);
unsigned int rx             = remote_xy >> Y_WIDTH;
unsigned int ry             = remote_xy & ((1<<Y_WIDTH)-1);
unsigned int rlpid          = rprocid % NB_PROCS_MAX;
_puts("\n[IRQS DEBUG] Processor[");
_putd(x );
_puts(",");
_putd(y );
_puts(",");
_putd(lpid );
_puts("] enters _bdv_isr() at cycle ");
_putd(_get_proctime() );
_puts("\n  for task ");
_putd(ltid );
_puts(" running on processor[");
_putd(rx );
_puts(",");
_putd(ry );
_puts(",");
_putd(rlpid );
_puts(" / bdv status = ");
_putx(_bdv_status );
_puts("\n");
#endif

    // re-activates sleeping task
    _set_task_slot( rprocid,     // global processor index
                    ltid,        // local task index on processor
                    CTX_RUN_ID,  // CTX_RUN slot 
                    1 );         // running

    // requires a context switch for remote processor running the waiting task 
    _xcu_send_wti( remote_xy,    // cluster index
                   lpid,         // local processor index
                   0 );          // don't force context switch if not idle
}


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