/*
 * soclib_mty.c - soclib mty driver implementation.
 *
 * Author  Alain Greiner (2016,2017,2018)
 *
 * Copyright (c)  UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-MKH..
 *
 * ALMOS-MKH. 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; version 2.0 of the License.
 *
 * ALMOS-MKH. 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 ALMOS-MKH.; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */


#include <hal_kernel_types.h>
#include <dev_txt.h>
#include <chdev.h>
#include <soclib_mty.h>
#include <thread.h>
#include <printk.h>
#include <hal_special.h>

extern   chdev_directory_t    chdev_dir;  // allocated in the kernel_init.c file.

////////////////////////////////////////////////////////////////////////////////////
// These global variables implement the MTY_RX  FIFOs (one per channel)
////////////////////////////////////////////////////////////////////////////////////
// Implementation note:
// We allocate - in each cluster - two arrays of FIFOs containing as many entries
// as the total number of TXT channels, but all entries are not used in all
// clusters: for a given cluster K, a given entry corresponding to a given channel
// and a given direction is only used if the associated chdev is in cluster K.
// With this policy, the driver can ignore the actual placement of chdevs.
////////////////////////////////////////////////////////////////////////////////////

__attribute__((section(".kdata")))
mty_fifo_t  mty_rx_fifo[CONFIG_MAX_TXT_CHANNELS];

__attribute__((section(".kdata")))
mty_fifo_t  mty_tx_fifo[CONFIG_MAX_TXT_CHANNELS];

////////////////////////////////////////////////////////////////////////////////////
// These global variables define the physical channel RX and TX state,
// as required by the virtual channels handling.
////////////////////////////////////////////////////////////////////////////////////
// Implementation note:
// These state variables are required, because the ISR is called twice for each
// character on the physical channel (for index and value), and does not the same
// actions for index and value. They are also used to implement the round-robin
// policy between TX_FIFOs.
////////////////////////////////////////////////////////////////////////////////////

__attribute__((section(".kdata")))
bool_t      mty_rx_not_new;                // RX first byte if false

__attribute__((section(".kdata")))
uint32_t    mty_rx_channel;                // RX virtual channel index

__attribute__((section(".kdata")))
bool_t      mty_tx_not_new;                // TX first byte if false

__attribute__((section(".kdata")))
uint32_t    mty_tx_value;                  // TX character ascii value

__attribute__((section(".kdata")))
uint32_t    mty_tx_last;                   // TX last selected virtual channel

///////////////////////////////////////
void soclib_mty_init( chdev_t * chdev )
{
    xptr_t reg_xp;

    // initialise function pointers in chdev
    chdev->cmd = &soclib_mty_cmd;
    chdev->isr = &soclib_mty_isr;
    chdev->aux = &soclib_mty_aux;

    // get MTY channel and extended pointer on MTY peripheral base address
    xptr_t   mty_xp  = chdev->base;
    uint32_t channel = chdev->channel;
    bool_t   is_rx   = chdev->is_rx;

    // get SOCLIB_MTY device cluster and local pointer
    cxy_t      mty_cxy = GET_CXY( mty_xp );
    uint32_t * mty_ptr = GET_PTR( mty_xp );

    // enable interruptions for RX 
    reg_xp = XPTR( mty_cxy , mty_ptr + MTY_CONFIG );
    hal_remote_s32( reg_xp , MTY_CONFIG_RX_ENABLE );

    // reset relevant FIFO
    if( is_rx )
    {
        mty_rx_fifo[channel].sts = 0;
        mty_rx_fifo[channel].ptr = 0;
        mty_rx_fifo[channel].ptw = 0;
    }
    else
    {
        mty_tx_fifo[channel].sts = 0;
        mty_tx_fifo[channel].ptr = 0;
        mty_tx_fifo[channel].ptw = 0;
    }
}  // end soclib_mty_init()

//////////////////////////////////////////////////////////////
void __attribute__ ((noinline)) soclib_mty_cmd( xptr_t th_xp )
{
    mty_fifo_t * fifo;     // MTY_RX or MTY_TX FIFO
    char         byte;     // byte value
    uint32_t     done;     // number of bytes moved

    // get client thread cluster and local pointer
    cxy_t      th_cxy = GET_CXY( th_xp );
    thread_t * th_ptr = GET_PTR( th_xp );

    // get command arguments
    uint32_t type     = hal_remote_l32 ( XPTR( th_cxy , &th_ptr->txt_cmd.type   ) );
    xptr_t   buf_xp   = hal_remote_l64( XPTR( th_cxy , &th_ptr->txt_cmd.buf_xp ) );
    uint32_t count    = hal_remote_l32 ( XPTR( th_cxy , &th_ptr->txt_cmd.count  ) );
    xptr_t   error_xp = XPTR( th_cxy , &th_ptr->txt_cmd.error );

    // get TXT device cluster and pointers
    xptr_t     dev_xp = (xptr_t)hal_remote_l64( XPTR( th_cxy , &th_ptr->txt_cmd.dev_xp ) );
    cxy_t      dev_cxy = GET_CXY( dev_xp );
    chdev_t  * dev_ptr = GET_PTR( dev_xp );

    // get MTY channel index and channel base address
    uint32_t   channel = hal_remote_l32( XPTR( dev_cxy , &dev_ptr->channel ) );

    ///////////////////////
    if( type == TXT_WRITE )         // write bytes to MTY_TX FIFO
    {
        fifo = &mty_tx_fifo[channel];

        done = 0;

        while( done < count )
        {
            if( fifo->sts < MTY_FIFO_DEPTH )   // put one byte to FIFO if TX_FIFO not full
            {
                // get one byte from command buffer
                byte = hal_remote_lb( buf_xp + done );

#if DEBUG_HAL_TXT_TX
uint32_t tx_cycle = (uint32_t)hal_get_cycles();
if( DEBUG_HAL_TXT_TX < tx_cycle )
printk("\n[DBG] %s : thread %x put character <%c> to TXT%d_TX fifo / cycle %d\n",
__FUNCTION__, CURRENT_THREAD, byte, channel, tx_cycle );
#endif
                // write byte to FIFO
                fifo->data[fifo->ptw] = byte;

                // prevent race
                hal_fence();

                // update FIFO state
                fifo->ptw = (fifo->ptw + 1) % MTY_FIFO_DEPTH;
                hal_atomic_add( &fifo->sts , 1 );

                // udate number of bytes moved
                done++;
            }
            else                                // block & deschedule if TX_FIFO full
            {
                // block on ISR
                thread_block( XPTR( local_cxy , CURRENT_THREAD ) , THREAD_BLOCKED_ISR );

                // deschedule
                sched_yield( "MTY_TX_FIFO full" ); 
            }
        }

        // set error status in command and return
        hal_remote_s32( error_xp , 0 );
    }
    ///////////////////////////
    else if( type == TXT_READ )       // read bytes from MTY_RX FIFO   
    {
        fifo = &mty_rx_fifo[channel];

        done = 0;

        while( done < count )
        {
            if( fifo->sts > 0 )               // get byte from FIFO if not empty
            {
                // get one byte from FIFO
                char byte = fifo->data[fifo->ptr];

#if DEBUG_HAL_TXT_RX
uint32_t rx_cycle = (uint32_t)hal_get_cycles();
if( DEBUG_HAL_TXT_RX < rx_cycle )
printk("\n[DBG] %s : thread %x get character <%c> from TXT%d_RX fifo / cycle %d\n",
__FUNCTION__, CURRENT_THREAD, byte, channel, rx_cycle );
#endif
                // update FIFO state
                fifo->ptr = (fifo->ptr + 1) % MTY_FIFO_DEPTH;
                hal_atomic_add( &fifo->sts , -1 );

                // set byte to command buffer
                hal_remote_sb( buf_xp + done , byte );

                // udate number of bytes
                done++;
            }
            else                             //  deschedule if FIFO empty
            {
                // block on ISR
                thread_block( XPTR( local_cxy , CURRENT_THREAD ) , THREAD_BLOCKED_ISR );
    
                // deschedule
                sched_yield( "MTY_RX_FIFO empty" );
            }
        }  // end while

        // set error status in command
        hal_remote_s32( error_xp , 0 );
    }
    else
    {
        assert( false , __FUNCTION__ , "illegal TXT command\n" );
    }

}  // end soclib_mty_cmd()

/////////////////////////////////////////////////////////////////
void __attribute__ ((noinline)) soclib_mty_isr( chdev_t * chdev )
{
    thread_t   * server;            // pointer on TXT chdev server thread
    lid_t        server_lid;        // local index of core running the server thread
    uint32_t     channel;           // TXT chdev channel (virtual channel index)
    bool_t       is_rx;             // TXT chdev direction
    char         byte;              // byte value
    xptr_t       owner_xp;          // extended pointer on TXT owner process
    cxy_t        owner_cxy;         // TXT owner process cluster
    process_t  * owner_ptr;         // local pointer on TXT owner process
    pid_t        owner_pid;         // TXT owner process identifier
    mty_fifo_t * fifo;              // pointer on MTY_TX or MTY_RX FIFO
    cxy_t        mty_cxy;           // soclib_mty cluster
    uint32_t   * mty_ptr;           // soclib_mty segment base address
    xptr_t       status_xp;         // extended pointer on MTY_STATUS register
    xptr_t       write_xp;          // extended pointer on MTY_WRITE register
    xptr_t       read_xp;           // extended pointer on MTY_READ register
    xptr_t       parent_xp;         // extended pointer on parent process
    cxy_t        parent_cxy;        // parent process cluster
    process_t  * parent_ptr;        // local pointer on parent process
    thread_t   * parent_main_ptr;   // extended pointer on parent process main thread
    xptr_t       parent_main_xp;    // local pointer on parent process main thread
    uint32_t     n;                 // index in loop
    bool_t       found;

#if DEBUG_HAL_TXT_RX
uint32_t rx_cycle = (uint32_t)hal_get_cycles();
#endif

#if DEBUG_HAL_TXT_TX
uint32_t tx_cycle = (uint32_t)hal_get_cycles();
#endif

    // get TXT chdev channel, direction and server thread
    is_rx      = chdev->is_rx;
    server     = chdev->server;
    server_lid = server->core->lid;

    // get SOCLIB_MTY peripheral cluster and local pointer
    mty_cxy = GET_CXY( chdev->base );
    mty_ptr = GET_PTR( chdev->base );

    // get extended pointer on MTY registers
    status_xp = XPTR( mty_cxy , mty_ptr + MTY_STATUS );
    write_xp  = XPTR( mty_cxy , mty_ptr + MTY_WRITE );
    read_xp   = XPTR( mty_cxy , mty_ptr + MTY_READ );

    /////////////////////////// handle RX //////////////////////
    if( is_rx )
    {
        // check one byte available in MTY_READ register
        if( hal_remote_l32( status_xp ) & MTY_STATUS_RX_FULL )   
        {
            // get one byte from MTY_READ register & acknowledge RX_IRQ
            byte = (char)hal_remote_lb( read_xp );

            // test physical RX channel state
            if( mty_rx_not_new == false )      // get first byte (virtual channel index)
            {
                // register virtual channel index
                mty_rx_channel = (uint32_t)byte;

                // update physical RX channel state
                mty_rx_not_new = true;
            }
            else                               // get second byte (character value)
            {
                // get virtual channel index registered
                channel = mty_rx_channel;

                // get destination TX_FIFO
                fifo = &mty_rx_fifo[channel];

                // filter special character ^Z  => block TXT owner process
                if( byte == 0x1A ) 
                {

#if DEBUG_HAL_TXT_RX
if( DEBUG_HAL_TXT_RX < rx_cycle )
printk("\n[DBG] %s : read ^Z character from TXT%d\n", __FUNCTION__, channel );
#endif
                    // get pointers on TXT owner process in owner cluster
                    owner_xp  = process_txt_get_owner( channel );
               
                    // check process exist
                    assert( (owner_xp != XPTR_NULL) , __FUNCTION__, 
                    "TXT owner process not found\n" );

                    // get relevant infos on TXT owner process
                    owner_cxy = GET_CXY( owner_xp );
                    owner_ptr = GET_PTR( owner_xp );
                    owner_pid = hal_remote_l32( XPTR( owner_cxy , &owner_ptr->pid ) );

                    // block TXT owner process only if it is not the INIT process 
                    if( owner_pid != 1 )
                    {
                        // get parent process descriptor pointers
                        parent_xp = hal_remote_l64( XPTR( owner_cxy , 
                                                    &owner_ptr->parent_xp ) );
                        parent_cxy = GET_CXY( parent_xp );
                        parent_ptr = GET_PTR( parent_xp );

                        // get pointers on the parent process main thread
                        parent_main_ptr = hal_remote_lpt( XPTR(parent_cxy,
                                                          &parent_ptr->th_tbl[0])); 
                        parent_main_xp  = XPTR( parent_cxy , parent_main_ptr );

                        // transfer TXT ownership 
                        process_txt_transfer_ownership( owner_xp );

                        // block all threads in all clusters, but the main thread
                        process_sigaction( owner_pid , BLOCK_ALL_THREADS );

                        // block the main thread
                        xptr_t main_xp = XPTR( owner_cxy , &owner_ptr->th_tbl[0] );
                        thread_block( main_xp , THREAD_BLOCKED_GLOBAL );

                        // atomically update owner process termination state
                        hal_remote_atomic_or( XPTR( owner_cxy , &owner_ptr->term_state ) ,
                                              PROCESS_TERM_STOP );

                        // take the children lock and unblock the parent process main thread 
                        thread_unblock( parent_main_xp , THREAD_BLOCKED_WAIT );

                        return;
                    }
                }

                // filter special character ^C  => kill TXT owner process
                if( byte == 0x03 )
                {

#if DEBUG_HAL_TXT_RX
if( DEBUG_HAL_TXT_RX < rx_cycle )
printk("\n[DBG] %s : read ^C character from TXT%d\n", __FUNCTION__, channel );
#endif
                    // get pointer on TXT owner process in owner cluster
                    owner_xp  = process_txt_get_owner( channel );

                    // check process exist
                    assert( (owner_xp != XPTR_NULL) , __FUNCTION__,
                    "TXT owner process not found\n" );

                    // get relevant infos on TXT owner process
                    owner_cxy = GET_CXY( owner_xp );
                    owner_ptr = GET_PTR( owner_xp );
                    owner_pid = hal_remote_l32( XPTR( owner_cxy , &owner_ptr->pid ) );

                    // kill TXT owner process only if it is not the INIT process
                    if( owner_pid != 1 )
                    {
                        // get parent process descriptor pointers
                        parent_xp  = hal_remote_l64( XPTR( owner_cxy,
                                                     &owner_ptr->parent_xp ) );
                        parent_cxy = GET_CXY( parent_xp );
                        parent_ptr = GET_PTR( parent_xp );

                        // get pointers on the parent process main thread
                        parent_main_ptr = hal_remote_lpt( XPTR( parent_cxy,
                                                          &parent_ptr->th_tbl[0])); 
                        parent_main_xp  = XPTR( parent_cxy , parent_main_ptr );

                        // remove process from TXT list
                        process_txt_detach( owner_xp );

                        // mark for delete all thread in all clusters, but the main
                        process_sigaction( owner_pid , DELETE_ALL_THREADS );
                
                        // block main thread
                        xptr_t main_xp = XPTR( owner_cxy , &owner_ptr->th_tbl[0] );
                        thread_block( main_xp , THREAD_BLOCKED_GLOBAL );

                        // atomically update owner process termination state
                        hal_remote_atomic_or( XPTR( owner_cxy , &owner_ptr->term_state ) ,
                                              PROCESS_TERM_KILL );

                        // take the children lock and unblock the parent process main thread 
                        thread_unblock( parent_main_xp , THREAD_BLOCKED_WAIT );

                        return;
                    }
                }

                // write byte in RX FIFO if not full / discard byte if full
                if ( fifo->sts < MTY_FIFO_DEPTH )
                {

#if DEBUG_HAL_TXT_RX
if( DEBUG_HAL_TXT_RX < rx_cycle )
printk("\n[DBG] %s : put character <%c> to TXT%d_RX fifo\n",
__FUNCTION__, byte, channel );
#endif
                    // store byte into FIFO 
                    fifo->data[fifo->ptw] = (char)byte; 

                    // avoid race 
                    hal_fence();

                    // update RX_FIFO state
                    fifo->ptw = (fifo->ptw + 1) % MTY_FIFO_DEPTH;
                    hal_atomic_add( &fifo->sts , 1 );

                    // unblock TXT_RX server thread 
                    thread_unblock( XPTR( local_cxy , server ) , THREAD_BLOCKED_ISR );

                    // send IPI to core running server thread
                    dev_pic_send_ipi( local_cxy , server_lid );
                }
                else
                {
                    printk("\n[WARNING] %s : MTY_RX_FIFO[%d] full => discard char <%x>\n",
                    __FUNCTION__, channel, (uint32_t)byte );
                }

                // update physical RX channel state
                mty_rx_not_new = true;

            }  // end get character value
        }  // end if byte available in MTY_READ register
    }  // end RX

    ///////////////////////  handle TX  /////////////////////////////
    else
    {
        // test physical TX channel state
        if( mty_tx_not_new == false )      // send first byte (virtual channel index)
        {
            // scan the set of the TX_FIFO
            for( n = 0 , found = false ; n < CONFIG_MAX_TXT_CHANNELS ; n++ )
            {
                // implement round-robin policy
                channel = (n + mty_tx_last + 1) % CONFIG_MAX_TXT_CHANNELS;

                // get pointer on TX_FIFO[channel]
                fifo = &mty_tx_fifo[channel];

                if( fifo->sts > 0 )
                {
                    found = true;
                    break;
                }
            }

            // get one byte from TX_FIFO if found and send channel index
            if( found ) 
            {
                // get one byte from selected TX_FIFO
                byte = fifo->data[fifo->ptr];

#if DEBUG_HAL_TXT_TX
if( DEBUG_HAL_TXT_TX < tx_cycle )
printk("\n[DBG] %s : get character <%c> from TXT%d_TX fifo\n",
__FUNCTION__, byte, channel );
#endif
                // update TX_FIFO state
                fifo->ptr = (fifo->ptr + 1) % MTY_FIFO_DEPTH;
                hal_atomic_add( &fifo->sts , -1 );

                // update TX physical channel state
                mty_tx_value   = (uint32_t)byte;
                mty_tx_not_new = true;
                mty_tx_last    = channel;

                // write virtual channel index to TX_WRITE register
                hal_remote_sb( write_xp , (uint8_t)channel );

                // unblock TXT_TX server thread
                thread_unblock( XPTR( local_cxy , server ) , THREAD_BLOCKED_ISR );

                // send IPI to core running server thread
                dev_pic_send_ipi( local_cxy , server_lid );
            }
        }
        else                             // send second byte (character value) 
        {
            // write registered character value to TX_WRITE register
            hal_remote_sb( write_xp , (uint8_t)mty_tx_value );

            // update TX physical channel state
            mty_tx_not_new = false;
        }  // end if MTY_WRITE register empty
    }  // end TX

    hal_fence();

}  // end soclib_mty_isr()

/////////////////////////////////////////////////////////////
void __attribute__ ((noinline)) soclib_mty_aux( void * args )
{
    uint32_t   i;

    xptr_t       dev_xp  = ((txt_sync_args_t *)args)->dev_xp;
    const char * buffer  = ((txt_sync_args_t *)args)->buffer;
    uint32_t     count   = ((txt_sync_args_t *)args)->count;
    uint32_t     channel = ((txt_sync_args_t *)args)->channel;
    
    // get chdev cluster and local pointer
    cxy_t     dev_cxy = GET_CXY( dev_xp );
    chdev_t * dev_ptr = GET_PTR( dev_xp );

    // get extended pointer on MTY channel base address
    xptr_t mty_xp = (xptr_t)hal_remote_l64( XPTR( dev_cxy , &dev_ptr->base ) );

    // get MTY channel segment cluster and local pointer
    cxy_t      mty_cxy = GET_CXY( mty_xp );
    uint32_t * mty_ptr = GET_PTR( mty_xp );

    // get extended pointers on MTY_WRITE & MTY_STATUS registers
    xptr_t write_xp  = XPTR( mty_cxy , mty_ptr + MTY_WRITE );
    xptr_t status_xp = XPTR( mty_cxy , mty_ptr + MTY_STATUS );

    // loop on characters (two bytes per character)
    for( i = 0 ; i < count ; i++ )
    {
        // write virtual channel index to MTY_WRITE register
        hal_remote_sb( write_xp , (uint8_t)channel );

        // write character value to MTY_WRITE register
        hal_remote_sb( write_xp , buffer[i] );
    }
}  // end soclib_mty_aux()



