source: trunk/boot/tsar_mips32/boot.c @ 665

/*
 * boot.c - TSAR bootloader implementation.
 * 
 * Authors :   Vu Son  (2016)
 *             Alain Greiner (2016,2017,2018,2019)
 *
 * 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
 */

/****************************************************************************
 * This file contains the ALMOS-MKH. boot-loader for the TSAR architecture. *
 * that is a clusterised, shared memory, multi-processor architecture,      *
 * where each processor core is identified by a composite index [cxy,lid]   *
 * with one physical memory bank per cluster.                               *
 *                                                                          *
 * The 'boot.elf' file (containing the boot-loader binary code) is stored   *
 * on disk (not in the FAT file system), and must be loaded into memory     *
 * by the generic (OS undependant) preloader.                               *
 *                                                                          *
 * The main task of the boot-loader is to load in the first physical page   *
 * of each cluster a copy of the kernel code (segments "kcode" and "kdata") *
 * and to build - in each cluster - a cluster specific description of the   *
 * hardware archtecture, stored in the "kdata" segment as the boot_info_t   *
 * structure. These "kernel.elf" and "arch_info.bin" files are supposed     *
 * to be stored on disk in a FAT32 file system.                             *
 *                                                                          *
 * All cores contribute to the boot procedure, but all cores are not        *
 * simultaneously active:                                                   *
 * - in a first phase, only core[0][0] is running (core 0 in cluster 0).    * 
 * - in a second phase, only core[cxy][0] is running in each cluster.       *
 * - in last phase, all core[cxy][lid] are running.                         *
 *                                                                          *
 * Finally, all cores jump to the kernel_init() function that makes the     *                 
 * actual kernel initialisation.                                            *
 *                                                                          *
 * Implementation note:                                                     *
 *                                                                          *
 * To allows each core to use the local copy of both the boot code and the  *
 * kernel code, the boot-loader builds a minimal and temporary BPT (Boot    *
 * Page Table) containing only two big pages: page[0] maps the kernel code, *
 * and page 1 maps the boot code.                                           *
 ****************************************************************************/

#include <elf-types.h>
#include <hal_kernel_types.h>

#include <kernel_config.h>
#include <boot_config.h>

#include <arch_info.h>
#include <boot_info.h>

#include <boot_utils.h>
#include <boot_fat32.h>
#include <boot_bdv_driver.h>
#include <boot_hba_driver.h>
#include <boot_tty_driver.h>

/*****************************************************************************
 *                                 Macros.                              
 ****************************************************************************/

#define PAGE_ROUND_DOWN(x)  ((x) & (~PPM_PAGE_SIZE -1))
#define PAGE_ROUND_UP(x)    (((x) + PPM_PAGE_SIZE-1) &   \
                            (~(PPM_PAGE_SIZE-1)))

/*****************************************************************************
 *                             Global variables.                            
 ****************************************************************************/

// the Boot Page Table contains two PTE1, and should be aligned on 8 Kbytes 

uint32_t                        boot_pt[2] __attribute__((aligned(0x2000)));

// synchronization variables. 

volatile boot_remote_spinlock_t tty0_lock;        // protect TTY0 access
volatile boot_remote_barrier_t  global_barrier;   // synchronize CP0 cores
volatile boot_remote_barrier_t  local_barrier;    // synchronize cores in one cluster
uint32_t                        active_cores_nr;  // number of expected CP0s
 
// kernel segments layout variables

uint32_t                        seg_kcode_base;   // kcode segment base address
uint32_t                        seg_kcode_size;   // kcode segment size (bytes) 
uint32_t                        seg_kdata_base;   // kdata segment base address
uint32_t                        seg_kdata_size;   // kdata segment size (bytes) 

uint32_t                        kernel_entry;     // kernel_init() function

// Functions 

extern void boot_entry( void );    // boot_loader entry point
extern void boot_loader( lid_t lid, cxy_t cxy );


#if DEBUG_BOOT_INFO
/*********************************************************************************
 * This debug function returns the printable string for each device type.
 ********************************************************************************/
static char * device_type_str( enum device_types_e dev_type ) 
{
    switch ( dev_type ) 
    {
        case DEV_TYPE_RAM_SCL: return "RAM_SCL";
        case DEV_TYPE_ROM_SCL: return "ROM_SCL";
        case DEV_TYPE_FBF_SCL: return "FBF_SCL";
        case DEV_TYPE_IOB_TSR: return "IOB_TSR";
        case DEV_TYPE_IOC_BDV: return "IOC_BDV";
        case DEV_TYPE_IOC_HBA: return "IOC_HBA";
        case DEV_TYPE_IOC_SDC: return "IOC_SDC";
        case DEV_TYPE_IOC_SPI: return "IOC_SPI";
        case DEV_TYPE_IOC_RDK: return "IOC_RDK";
        case DEV_TYPE_MMC_TSR: return "MMC_TSR";
        case DEV_TYPE_DMA_SCL: return "DMA_SCL";
        case DEV_TYPE_NIC_CBF: return "NIC_CBF";
        case DEV_TYPE_TIM_SCL: return "TIM_SCL";
        case DEV_TYPE_TXT_TTY: return "TXT_TTY";
        case DEV_TYPE_TXT_MTY: return "TXT_MTY";
        case DEV_TYPE_ICU_XCU: return "ICU_XCU";
        case DEV_TYPE_PIC_TSR: return "PIC_TSR";
        default:               return "undefined";
    }
}
#endif

/************************************************************************************
 * This function loads the arch_info.bin file into the boot cluster memory.
 ***********************************************************************************/
static void boot_archinfo_load( void )
{
    archinfo_header_t * header = (archinfo_header_t*)ARCHINFO_BASE;  
    
    // Load file into memory
    if (boot_fat32_load(ARCHINFO_PATHNAME, ARCHINFO_BASE, ARCHINFO_MAX_SIZE))
    {
        boot_printf("\n[BOOT ERROR]in %s : <%s> file not found\n",
        __FUNCTION__, ARCHINFO_PATHNAME);
        boot_exit();
    }

    if (header->signature != ARCHINFO_SIGNATURE)
    {
        boot_printf("\n[BOOT_ERROR]: boot_archinfo_load(): "
        "<%s> file signature should be %x\n",
        ARCHINFO_PATHNAME, ARCHINFO_SIGNATURE);
        boot_exit();
    }

#if DEBUG_BOOT_INFO
boot_printf("\n[BOOT INFO] in %s : file %s loaded at address = %x\n",
__FUNCTION__ , ARCHINFO_PATHNAME , ARCHINFO_BASE );
#endif

} // boot_archinfo_load()

/**************************************************************************************
 * This function loads the 'kernel.elf' file into the boot cluster memory buffer,
 * analyzes it, and places the kcode and kdata segments at their final physical
 * adresses (defined the .elf file), and set the kernel layout global variables.
 *************************************************************************************/
static void boot_kernel_load( void )
{
    Elf32_Ehdr * elf_header;      // pointer on kernel.elf header.  
    Elf32_Phdr * program_header;  // pointer on kernel.elf program header. 
    uint32_t     phdr_offset;     // program header offset in kernel.elf file. 
    uint32_t     segments_nb;     // number of segments in kernel.elf file. 
    uint32_t     seg_src_addr;    // segment address in kernel.elf file (source).
    uint32_t     seg_paddr;       // segment local physical address of segment 
    uint32_t     seg_offset;      // segment offset in kernel.elf file
    uint32_t     seg_filesz;      // segment size (bytes) in kernel.elf file 
    uint32_t     seg_memsz;       // segment size (bytes) in memory image.
    bool_t       kcode_found;     // kcode segment found.
    bool_t       kdata_found;     // kdata segment found.
    uint32_t     seg_id;          // iterator for segments loop.

#if DEBUG_BOOT_ELF 
boot_printf("\n[BOOT INFO] %s enters for file %s at cycle %d\n",
__FUNCTION__ , KERNEL_PATHNAME , boot_get_proctime() );
#endif

    // Load kernel.elf file into memory buffer
    if ( boot_fat32_load(KERNEL_PATHNAME, KERN_BASE, KERN_MAX_SIZE) )
    {
        boot_printf("\n[BOOT ERROR] in %s : <%s> file not found\n",
                    KERNEL_PATHNAME);
        boot_exit();
    }

    // get pointer to kernel.elf header  
    elf_header = (Elf32_Ehdr*)KERN_BASE;

    // check signature 
    if ((elf_header->e_ident[EI_MAG0] != ELFMAG0)   ||
        (elf_header->e_ident[EI_MAG1] != ELFMAG1)   ||
        (elf_header->e_ident[EI_MAG2] != ELFMAG2)   ||
        (elf_header->e_ident[EI_MAG3] != ELFMAG3))
    {
        boot_printf("\n[BOOT_ERROR]: boot_kernel_load(): "
                    "<%s> is not an ELF file\n",
                    KERNEL_PATHNAME);
        boot_exit();
    }

    // Get program header table offset and number of segments
    phdr_offset     = elf_header->e_phoff;
    segments_nb     = elf_header->e_phnum;

    // Get program header table pointer
    program_header  = (Elf32_Phdr*)(KERN_BASE + phdr_offset);

    // loop on segments
    kcode_found  = false;
    kdata_found  = false;
    for (seg_id = 0; seg_id < segments_nb; seg_id++) 
    {
        if (program_header[seg_id].p_type == PT_LOAD)   // Found one loadable segment
        {
            // Get segment attributes.
            seg_paddr    = program_header[seg_id].p_paddr;   
            seg_offset   = program_header[seg_id].p_offset;
            seg_filesz   = program_header[seg_id].p_filesz;
            seg_memsz    = program_header[seg_id].p_memsz;

            // get segment base address in buffer
            seg_src_addr = (uint32_t)KERN_BASE + seg_offset;

            // Load segment to its final physical memory address
            boot_memcpy( (void*)seg_paddr, 
                         (void*)seg_src_addr, 
                         seg_filesz );

#if DEBUG_BOOT_ELF 
boot_printf("\n[BOOT INFO] in %s for file %s : found loadable segment\n"
"   base = %x / size = %x\n",
__FUNCTION__ , KERNEL_PATHNAME , seg_paddr , seg_memsz );
#endif

            // Fill remaining memory with zero if (filesz < memsz).
            if( seg_memsz < seg_filesz )
            {
                boot_memset( (void*)(seg_paddr + seg_filesz), 0, seg_memsz - seg_filesz);
            }

            // Note: we suppose that the 'kernel.elf' file contains exactly
            // two loadable segments : kcode & kdata

            if( program_header[seg_id].p_paddr == KCODE_BASE )     // kcode segment
            {
                if( kcode_found )
                {
                    boot_printf("\n[BOOT_ERROR] in %s for file %s :\n"
                    "   two kcode segments found\n",
                    __FUNCTION__ , KERNEL_PATHNAME );
                    boot_exit();
                } 

                kcode_found     = true;
                seg_kcode_base = seg_paddr;
                seg_kcode_size = seg_memsz;
            }
            else                                                    // kdata segment
            {
                if( kdata_found )
                {
                    boot_printf("\n[BOOT_ERROR] in %s for file %s :\n"
                    "   two kdata segments found\n",
                    __FUNCTION__ , KERNEL_PATHNAME );
                    boot_exit();
                } 

                kdata_found     = true;
                seg_kdata_base = seg_paddr;
                seg_kdata_size = seg_memsz;
            }
        }
    }

    // check kcode & kdata segments found
    if( kcode_found == false )
    {
        boot_printf("\n[BOOT_ERROR] in %s for file %s : seg_kcode not found\n",
        __FUNCTION__ , KERNEL_PATHNAME );
        boot_exit();
    }
    if( kdata_found == false )
    {
        boot_printf("\n[BOOT_ERROR] in %s for file %s : seg_kdata not found\n",
        __FUNCTION__ , KERNEL_PATHNAME );
        boot_exit();
    }

    // check segments sizes
    if( (seg_kcode_size + seg_kdata_size) > KCODE_MAX_SIZE )
    {
        boot_printf("\n[BOOT_ERROR] in %s for file %s : seg_kcode + seg_kdata too large\n",
        __FUNCTION__ , KERNEL_PATHNAME );
    }

    // set entry point 
    kernel_entry = (uint32_t)elf_header->e_entry;

#if DEBUG_BOOT_ELF 
boot_printf("\n[BOOT INFO] %s completed for file %s at cycle %d\n",
__FUNCTION__ , KERNEL_PATHNAME , boot_get_proctime() );
#endif

} // boot_kernel_load()

/*************************************************************************************
 * This function initializes the  boot_info_t structure for a given cluster. 
 * @ boot_info  : pointer to local boot_info_t structure  
 * @ cxy        : cluster identifier                    
 ************************************************************************************/
static void boot_info_init( boot_info_t * boot_info,
                            cxy_t         cxy )
{
    archinfo_header_t  * header;
    archinfo_core_t    * core_base;     
    archinfo_cluster_t * cluster_base; 
    archinfo_device_t  * device_base;
    archinfo_irq_t     * irq_base;  

    archinfo_cluster_t * cluster; 
    archinfo_cluster_t * my_cluster = NULL;   // target cluster
    archinfo_cluster_t * io_cluster = NULL;   // external peripherals cluster 

    archinfo_core_t    * core;
    uint32_t             core_id; 
    archinfo_device_t  * device;
    uint32_t             device_id;
    archinfo_irq_t     * irq; 
    uint32_t             irq_id;
    uint32_t             end;
    boot_device_t      * boot_dev; 

 #if DEBUG_BOOT_INFO
boot_printf("\n[BOOT INFO] %s : enter at cycle %d\n",
__FUNCTION__ , boot_get_proctime() );
#endif

   // get pointer on ARCHINFO header  and on the four arch_info arrays
    header       = (archinfo_header_t*)ARCHINFO_BASE;
    core_base    = archinfo_get_core_base   (header);
    cluster_base = archinfo_get_cluster_base(header);
    device_base  = archinfo_get_device_base (header);
    irq_base     = archinfo_get_irq_base    (header);

    // Initialize global platform parameters
    boot_info->x_size       = header->x_size;
    boot_info->y_size       = header->y_size;
    boot_info->x_width      = header->x_width;
    boot_info->y_width      = header->y_width;
    boot_info->paddr_width  = header->paddr_width;
    boot_info->io_cxy       = header->io_cxy;

    // Initialize kernel segments from global variables
    boot_info->kcode_base  = seg_kcode_base;
    boot_info->kcode_size  = seg_kcode_size;
    boot_info->kdata_base  = seg_kdata_base;
    boot_info->kdata_size  = seg_kdata_size;

    // loop on arch_info clusters to build cluster_info[][] array
    // and get io_cluster and my_cluster pointers 
    for (cluster =  cluster_base;
         cluster < &cluster_base[header->x_size * header->y_size];
         cluster++)
    {
        int x = cluster->cxy >> Y_WIDTH;
        int y = cluster->cxy & ((1 << Y_WIDTH) - 1);
        boot_info->cluster_info[x][y] = (uint8_t)cluster->cores;

        if( cluster->cxy == cxy )            my_cluster = cluster;
        if( cluster->cxy == header->io_cxy ) io_cluster = cluster;
    }

    if( my_cluster == NULL ) 
    {
        boot_printf("\n[ERROR] in %s : cannot found cluster %x in arch_info\n",
        __FUNCTION__ , cxy );
        boot_exit();
    }

    if( io_cluster == NULL ) 
    {
        boot_printf("\n[ERROR] in %s : cannot found io_cluster %x in arch_info\n",
        __FUNCTION__ , cxy );
        boot_exit();
    }

    //////////////////////////////////////////////////////////
    // initialize the boot_info array of external peripherals

#if DEBUG_BOOT_INFO
boot_printf("\n[BOOT INFO] %s : external peripherals at cycle %d\n",
__FUNCTION__ , boot_get_proctime() );
#endif

    device_id = 0;
    for (device = &device_base[io_cluster->device_offset];
         device < &device_base[io_cluster->device_offset + io_cluster->devices];
         device++ )
    {
        if( device_id >= CONFIG_MAX_EXT_DEV ) 
        {
            boot_printf("\n[ERROR] in %s : too much external devices in arch_info\n",
            __FUNCTION__ );
            boot_exit();
        }
        
        // keep only external devices
        if( (device->type != DEV_TYPE_RAM_SCL) &&
            (device->type != DEV_TYPE_ICU_XCU) &&
            (device->type != DEV_TYPE_MMC_TSR) &&
            (device->type != DEV_TYPE_DMA_SCL) &&
            (device->type != DEV_TYPE_TXT_MTY) &&
            (device->type != DEV_TYPE_IOC_SPI) ) 
        {
            boot_dev = &boot_info->ext_dev[device_id];

            boot_dev->type     = device->type;
            boot_dev->base     = device->base;
            boot_dev->channels = device->channels;
            boot_dev->param0   = device->arg0;    
            boot_dev->param1   = device->arg1;    
            boot_dev->param2   = device->arg2;    
            boot_dev->param3   = device->arg3;    
            boot_dev->irqs     = device->irqs;    

            device_id++;

#if DEBUG_BOOT_INFO
boot_printf("  - %s : base = %l / size = %l / channels = %d / irqs = %d\n",
device_type_str(device->type), device->base, device->size, device->channels, device->irqs );
#endif
        }
    
        // handle IRQs for PIC
        if (device->type == DEV_TYPE_PIC_TSR) 
        {
            for (irq_id = 0; irq_id < CONFIG_MAX_EXTERNAL_IRQS ; irq_id++)
            {
                boot_dev->irq[irq_id].valid  = 0;
            }

            for (irq = &irq_base[device->irq_offset];
                 irq < &irq_base[device->irq_offset + device->irqs];
                 irq++)
            {
                boot_dev->irq[irq->port].valid    = 1;
                boot_dev->irq[irq->port].dev_type = irq->dev_type;
                boot_dev->irq[irq->port].channel  = irq->channel;
                boot_dev->irq[irq->port].is_rx    = irq->is_rx;

#if DEBUG_BOOT_INFO
boot_printf("    . irq_port = %d / source = %s / channel = %d / is_rx = %d\n",
irq->port , device_type_str( irq->dev_type ) , irq->channel , irq->is_rx );
#endif
            }
        }
    }   // end loop on io_cluster peripherals

    // initialize number of external peripherals
    boot_info->ext_dev_nr = device_id;

    // Initialize cluster specific resources
    boot_info->cxy  = my_cluster->cxy;

#if DEBUG_BOOT_INFO
boot_printf("\n[BOOT INFO] %s : cores in cluster %x\n", __FUNCTION__ , cxy );
#endif

    ////////////////////////////////////////
    // Initialize array of core descriptors
    core_id = 0;
    for (core = &core_base[my_cluster->core_offset];
         core < &core_base[my_cluster->core_offset + my_cluster->cores];
         core++ )
    {
        boot_info->core[core_id].gid = (gid_t)core->gid;
        boot_info->core[core_id].lid = (lid_t)core->lid; 
        boot_info->core[core_id].cxy = (cxy_t)core->cxy;

#if DEBUG_BOOT_INFO
boot_printf("  - core_gid = %x : cxy = %x / lid = %d\n", 
core->gid , core->cxy , core->lid );
#endif
        core_id++;
    }

    // Initialize number of cores in my_cluster
    boot_info->cores_nr = core_id;

    //////////////////////////////////////////////////////////////////////
    // initialise boot_info array of internal devices (RAM, ICU, MMC, DMA)

#if DEBUG_BOOT_INFO
boot_printf("\n[BOOT INFO] %s : internal peripherals in cluster %x\n",
__FUNCTION__ , cxy );
#endif

    device_id = 0;
    for (device = &device_base[my_cluster->device_offset];
         device < &device_base[my_cluster->device_offset + my_cluster->devices];
         device++ )
    {
        // keep only internal devices
        if( (device->type == DEV_TYPE_RAM_SCL) ||
            (device->type == DEV_TYPE_ICU_XCU) ||
            (device->type == DEV_TYPE_MMC_TSR) ||
            (device->type == DEV_TYPE_DMA_SCL) ||
            (device->type == DEV_TYPE_TXT_MTY) ||
            (device->type == DEV_TYPE_IOC_SPI) )
        {
            if (device->type == DEV_TYPE_RAM_SCL)   // RAM
            {
                // set number of physical memory pages
                boot_info->pages_nr   = device->size >> CONFIG_PPM_PAGE_SHIFT;

#if DEBUG_BOOT_INFO
boot_printf("  - RAM : %x pages\n", boot_info->pages_nr );
#endif
            }
            else                                    // ICU / MMC / DMA / MTY
            {
                if( device_id >= CONFIG_MAX_INT_DEV ) 
                {
                    boot_printf("\n[ERROR] in %s : too much internal devices in cluster %x\n",
                                __FUNCTION__ , cxy );
                    boot_exit();
                }
        
                boot_dev = &boot_info->int_dev[device_id];

                boot_dev->type     = device->type;
                boot_dev->base     = device->base;
                boot_dev->channels = device->channels;
                boot_dev->param0   = device->arg0;    
                boot_dev->param1   = device->arg1;    
                boot_dev->param2   = device->arg2;    
                boot_dev->param3   = device->arg3;    
                boot_dev->irqs     = device->irqs; 

                device_id++;

#if DEBUG_BOOT_INFO
boot_printf("  - %s : base = %l / size = %l / channels = %d / irqs = %d\n",
device_type_str( device->type ) , device->base , device->size ,
device->channels , device->irqs );   
#endif

                // handle IRQs for ICU
                if (device->type == DEV_TYPE_ICU_XCU) 
                {
                    for (irq_id = 0; irq_id < CONFIG_MAX_INTERNAL_IRQS ; irq_id++)
                    {
                        boot_dev->irq[irq_id].valid  = 0;
                    }

                    for (irq = &irq_base[device->irq_offset];
                         irq < &irq_base[device->irq_offset + device->irqs] ; irq++)
                    {
                        boot_dev->irq[irq->port].valid    = 1;
                        boot_dev->irq[irq->port].dev_type = irq->dev_type;
                        boot_dev->irq[irq->port].channel  = irq->channel;
                        boot_dev->irq[irq->port].is_rx    = irq->is_rx;

#if DEBUG_BOOT_INFO
boot_printf("    . irq_port = %d / source = %s / channel = %d / is_rx = %d\n",
irq->port , device_type_str( irq->dev_type ) , irq->channel , irq->is_rx );
#endif

                    }
                }
            }
        }
    }  // end loop on local peripherals

    // initialize number of internal peripherals
    boot_info->int_dev_nr = device_id;

   // Get the top address of the kernel segments
    end = boot_info->kdata_base + boot_info->kdata_size;

    // compute number of physical pages occupied by the kernel code 
    boot_info->pages_offset = ( (end & CONFIG_PPM_PAGE_MASK) == 0 ) ?
                 (end >> CONFIG_PPM_PAGE_SHIFT) : (end >> CONFIG_PPM_PAGE_SHIFT) + 1;

    // no reserved zones for TSAR architecture
    boot_info->rsvd_nr = 0;

    // set boot_info signature
    boot_info->signature = BOOT_INFO_SIGNATURE;

} // boot_info_init()

/***********************************************************************************
 * This function check the local boot_info_t structure for a given core.
 * @ boot_info  : pointer to local 'boot_info_t' structure to be checked.
 * @ lid        : core local identifier, index the core descriptor table.
 **********************************************************************************/
static void boot_check_core( boot_info_t * boot_info, 
                             lid_t         lid)
{
    gid_t         gid;        // global hardware identifier of this core
    boot_core_t * this;       // BOOT_INFO core descriptor of this core.  

    // Get core hardware identifier 
    gid = (gid_t)boot_get_procid();

    // get pointer on core descriptor
    this = &boot_info->core[lid];

    if ( (this->gid != gid) ||  (this->cxy != boot_info->cxy) )
    {
        boot_printf("\n[BOOT ERROR] in boot_check_core() :\n"
                    " - boot_info cxy = %x\n"
                    " - boot_info lid = %d\n"
                    " - boot_info gid = %x\n"
                    " - actual    gid = %x\n",
                    this->cxy , this->lid , this->gid , gid );
        boot_exit();
    }

} // boot_check_core()

/*********************************************************************************
 * This function is called by CP0 in cluster(0,0) to activate all other CP0s.
 * It returns the number of CP0s actually activated.
 ********************************************************************************/
static uint32_t boot_wake_all_cp0s( void )
{
    archinfo_header_t*  header;         // Pointer on ARCHINFO header
    archinfo_cluster_t* cluster_base;   // Pointer on ARCHINFO clusters base
    archinfo_cluster_t* cluster;        // Iterator for loop on clusters
    archinfo_device_t*  device_base;    // Pointer on ARCHINFO devices base
    archinfo_device_t*  device;         // Iterator for loop on devices
    uint32_t            cp0_nb = 0;     // CP0s counter

    header       = (archinfo_header_t*)ARCHINFO_BASE;
    cluster_base = archinfo_get_cluster_base(header);
    device_base  = archinfo_get_device_base (header); 

    // loop on all clusters 
    for (cluster = cluster_base;
         cluster < &cluster_base[header->x_size * header->y_size];
         cluster++)
    {
        // Skip boot cluster.
        if (cluster->cxy == BOOT_CORE_CXY)
            continue;
            
        // Skip clusters without core (thus without CP0).
        if (cluster->cores == 0)
            continue;

        // Skip clusters without device (thus without XICU).
        if (cluster->devices == 0)
            continue;

        // search XICU device associated to CP0, and send a WTI to activate it 
        for (device = &device_base[cluster->device_offset];
             device < &device_base[cluster->device_offset + cluster->devices];
             device++)
        {
            if (device->type == DEV_TYPE_ICU_XCU)
            {

#if DEBUG_BOOT_WAKUP
boot_printf("\n[BOOT] core[%x,0] activated at cycle %d\n",
cluster->cxy , boot_get_proctime );
#endif

                boot_remote_sw((xptr_t)device->base, (uint32_t)boot_entry);
                cp0_nb++;
            }
        }
    }
    return cp0_nb;

} // boot_wake_cp0()

/*********************************************************************************
 * This function is called by all CP0s to activate the other CPi cores. 
 * @ boot_info  : pointer to local 'boot_info_t' structure.
 *********************************************************************************/
static void boot_wake_local_cores(boot_info_t * boot_info)
{
    unsigned int     core_id;        

    // get pointer on XCU device descriptor in boot_info
    boot_device_t *  xcu = &boot_info->int_dev[0];
 
    // loop on cores
    for (core_id = 1; core_id < boot_info->cores_nr; core_id++)
    {

#if DEBUG_BOOT_WAKUP
boot_printf("\n[BOOT] core[%x,%d] activated at cycle %d\n",
boot_info->cxy , core_id , boot_get_proctime() );
#endif
        // send an IPI 
        boot_remote_sw( (xptr_t)(xcu->base + (core_id << 2)) , (uint32_t)boot_entry ); 
    }
} // boot_wake_local_cores()

/*********************************************************************************
 * This function is called by all core[cxy][0] to initialize the Boot Page Table:
 * map two local big pages for the boot code and kernel code.
 * @ cxy    : local cluster identifier.
 *********************************************************************************/
void boot_page_table_init( cxy_t  cxy )
{
    // set PTE1 in slot[0] for kernel code
    uint32_t kernel_attr  = 0x8A800000;                   // flagss : V,C,X,G
    uint32_t kernel_ppn1  = (cxy << 20) >> 9;             // big physical page index == 0
    boot_pt[0]            = kernel_attr | kernel_ppn1;

    // set PTE1 in slot[1] for boot code (no global flag)
    uint32_t boot_attr    = 0x8A000000;                   // flags : V,C,X
    uint32_t boot_ppn1    = ((cxy << 20) + 512) >> 9;     // big physical page index == 1
    boot_pt[1]            = boot_attr | boot_ppn1;
}

/*********************************************************************************
 * This function is called by all cores to activate the instruction MMU,
 * and use the local copy of boot code.
 *********************************************************************************/
void boot_activate_ins_mmu( cxy_t cxy )
{
    // set mmu_ptpr register
    uint32_t ptpr = ((uint32_t)boot_pt >> 13) | (cxy << 19);
    asm volatile ( "mtc2   %0,   $0         \n" : : "r" (ptpr) );

    // set ITLB bit in mmu_mode 
    asm volatile ( "mfc2   $26,  $1         \n"
                   "ori    $26,  $26,  0x8  \n" 
                   "mtc2   $26,  $1         \n" );
}

/*********************************************************************************
 * This main function of the boot-loader is called by the  boot_entry()  
 * function, and executed by all cores. 
 * The arguments values are computed by the boot_entry code.
 * @ lid    : core local identifier,
 * @ cxy    : cluster identifier,
 *********************************************************************************/
void boot_loader( lid_t lid,
                  cxy_t cxy )
{
    boot_info_t * boot_info;       // pointer on local boot_info_t structure

    if (lid == 0) 
    {
        /************************************i**********************
         * PHASE Sequencial : only core[0,0] executes it 
         **********************************************************/
        if (cxy == 0)
        {
            // Initialize IOC driver 
            if      (USE_IOC_BDV) boot_bdv_init();
            else if (USE_IOC_HBA) boot_hba_init();
            // else if (USE_IOC_SDC) boot_sdc_init();
            // else if (USE_IOC_SPI) boot_spi_init();
            else if (!USE_IOC_RDK)
            {
                boot_printf("\n[BOOT ERROR] in %s : no IOC driver\n");
                boot_exit();
            }

            // Initialize FAT32. 
            boot_fat32_init();

            // Load the 'kernel.elf' file into memory from IOC, and set   
            // the global variables defining the kernel layout      
            boot_kernel_load();

            boot_printf("\n[BOOT] core[%x,%d] loaded kernel at cycle %d\n",
            cxy , lid , boot_get_proctime() );

            // Load the arch_info.bin file into memory.
            boot_archinfo_load();

            boot_printf("\n[BOOT] core[%x,%d] loaded arch_info at cycle %d\n",
            cxy , lid , boot_get_proctime() );

            // Get local boot_info_t structure base address.
            // It is the first structure in the .kdata segment. 
            boot_info = (boot_info_t *)seg_kdata_base;

            // Initialize local boot_info_t structure.
            boot_info_init( boot_info , cxy );

            boot_printf("\n[BOOT] core[%x,%d] initialised boot_info at cycle %d\n",
            cxy , lid , boot_get_proctime() );

            // check boot_info signature
            if (boot_info->signature != BOOT_INFO_SIGNATURE)
            {
                boot_printf("\n[BOOT ERROR] in %s reported by core[%x,%d]\n"
                "  illegal boot_info signature / should be %x\n",
                __FUNCTION__ , cxy , lid , BOOT_INFO_SIGNATURE );
                boot_exit();
            }

            // Check core information.
            boot_check_core(boot_info, lid);

            // identity maps two big pages for the boot and kernel code,
            boot_page_table_init( 0 );

            // activate the instruction MMU to use the local copy of boot code
            boot_activate_ins_mmu( 0 );

            // Activate other core[cxy,0] / set number of activated cores
            active_cores_nr = boot_wake_all_cp0s() + 1;

            // Wait until all clusters (i.e all core[cxy,0]) ready to enter kernel.
            boot_remote_barrier( XPTR( BOOT_CORE_CXY , &global_barrier ) ,
                                 active_cores_nr );

            // activate other local cores
            boot_wake_local_cores( boot_info );

            // Wait until all local cores in cluster ready
            boot_remote_barrier( XPTR( cxy , &local_barrier ) , 
                                 boot_info->cores_nr );
        }
        /**************************************************************************
         * PHASE partially parallel : all core[cxy,0] with (cxy != 0) execute it
         **************************************************************************/
        else
        {
            // at this point, the DATA extension registers point
            // on the local cluster cxy to use the local stack, 
            // but all cores must access the code stored in cluster 0 

            // Each core[cxy,0] copies the boot code (data and instructions)
            // from the cluster 0 to the local cluster.
            boot_remote_memcpy( XPTR( cxy           , BOOT_BASE ),
                                XPTR( BOOT_CORE_CXY , BOOT_BASE ),
                                BOOT_MAX_SIZE );

            // from now, it is safe to refer to the boot global variables 

#if DEBUG_BOOT_MULTI
boot_printf("\n[BOOT] core[%x,%d] replicated boot code at cycle %d\n",
cxy , lid , boot_get_proctime() );
#endif
            // identity maps two big pages for the boot and kernel code,
            boot_page_table_init( cxy );

            // activate the instruction MMU to use the local copy of boot code
            boot_activate_ins_mmu( cxy );

            // Each core[cxy,0] copies the arch_info.bin into the local memory.
            boot_remote_memcpy(XPTR(cxy,           ARCHINFO_BASE),
                               XPTR(BOOT_CORE_CXY, ARCHINFO_BASE),
                               ARCHINFO_MAX_SIZE );
#if DEBUG_BOOT_MULTI
boot_printf("\n[BOOT] core[%x,%d] replicated arch_info at cycle %d\n",
cxy , lid , boot_get_proctime() );
#endif
            // copy the kcode segment into local memory 
            boot_remote_memcpy( XPTR( cxy           , seg_kcode_base ),
                                XPTR( BOOT_CORE_CXY , seg_kcode_base ),
                                seg_kcode_size );

            // Each core[cxy,0] copies the kdata segment into local memory
            boot_remote_memcpy( XPTR( cxy           , seg_kdata_base ),
                                XPTR( BOOT_CORE_CXY , seg_kdata_base ),
                                seg_kdata_size );
#if DEBUG_BOOT_MULTI
boot_printf("\n[BOOT] core[%x,%d] replicated kernel code at cycle %d\n",
cxy , lid , boot_get_proctime() );
#endif
            // Each core[cxy,0] get local boot_info_t structure base address.
            boot_info = (boot_info_t*)seg_kdata_base;

            // Each core[cxy,0] initializes local boot_info_t structure.
            boot_info_init( boot_info , cxy );

#if DEBUG_BOOT_MULTI
boot_printf("\n[BOOT] core[%x,%d] initialised boot_info at cycle %d\n",
cxy , lid , boot_get_proctime() );
#endif
            // Each core[cxy,0] checks core information.
            boot_check_core( boot_info , lid );

            // Each core[cxy,0] get number of active clusters from BOOT_CORE cluster
            uint32_t count = boot_remote_lw( XPTR( 0 , &active_cores_nr ) );

            // Wait until all clusters (i.e all CP0s) ready 
            boot_remote_barrier( XPTR( BOOT_CORE_CXY , &global_barrier ) , count );

            // activate other local cores
            boot_wake_local_cores( boot_info );

            // Wait until all local cores in cluster ready
            boot_remote_barrier( XPTR( cxy , &local_barrier ) , 
                                 boot_info->cores_nr );
        }
    }
    else
    {
        /***********************************************************************
         * PHASE fully parallel : all cores[cxy,lid] with (lid! = 0) execute it
         **********************************************************************/

        // activate the instruction MMU to use the local copy of the boot code
        boot_activate_ins_mmu( cxy );

        // Get local boot_info_t structure base address.
        boot_info = (boot_info_t *)seg_kdata_base;

        // Check core information
        boot_check_core(boot_info, lid);

        // Wait until all local cores in cluster ready
        boot_remote_barrier( XPTR( cxy , &local_barrier ) , boot_info->cores_nr );
    }

    // All cores enter the kernel_init() function. The address is contained in 
    // the "kernel_entry" global variable, set by boot_kernel_load() function.
    // Each core initialise the following registers before jumping to kernel: 
    // - gr_29    : stack pointer / kernel stack allocated in idle thread descriptor,
    // - c0_sr    : status register / reset BEV bit
    // - gr_04    : kernel_init() argument / pointer on boot_info structure
    // The array of idle-thread descriptors is allocated in the kdata segment,
    // just after the boot_info structure.

#if DEBUG_BOOT_MULTI
boot_printf("\n[BOOT] core[%x,%d] jump to kernel_init = %x at cycle %d\n",
cxy, lid, kernel_entry, boot_get_proctime() );
#endif

    uint32_t base;
    uint32_t offset = sizeof( boot_info_t );
    uint32_t pmask  = CONFIG_PPM_PAGE_MASK;
    uint32_t psize  = CONFIG_PPM_PAGE_SIZE;
    if( offset & pmask ) base = seg_kdata_base + (offset & ~pmask) + psize;
    else                 base = seg_kdata_base + offset;
    uint32_t sp = base + ((lid + 1) * CONFIG_THREAD_DESC_SIZE) - 16;

    asm volatile( "mfc0  $27,  $12           \n"
                  "lui   $26,  0xFFBF        \n"
                  "ori   $26,  $26,  0xFFFF  \n"
                  "and   $27,  $27,  $26     \n"
                  "mtc0  $27,  $12           \n"
                  "move  $4,   %0            \n"
                  "move  $29,  %1            \n"
                  "jr    %2                  \n"
                  :
                  : "r"(boot_info) ,
                    "r"(sp) ,
                    "r"(kernel_entry) 
                  : "$26" , "$27" , "$29" , "$4" );


} // boot_loader()