///////////////////////////////////////////////////////////////////////////////////
// File     : kernel_init.c
// Date     : 26/05/2012
// Authors  : alain greiner & mohamed karaoui
// Copyright (c) UPMC-LIP6
////////////////////////////////////////////////////////////////////////////////////
// The kernel_init.c files is part of the GIET-VM nano-kernel.
// It contains the kernel entry point for the last step of system initialisation. 
// All procs in this phase have their MMU activated, and are running in parallel.
// Each processor perform the following actions:
// 1/ contributes to _schedulers_paddr[] initialisation
// 2/ contributes to _ptabs_paddr[] and _ptabs_vaddr arrays initialisation 
// 3/ computes and set the ICU mask for its private ICU channel
// 4/ initialises its private TICK timer (if required)
// 5/ initialises the "idle" task context in its private scheduler
// 6/ initialises the SP, SR, PTPR, EPC registers
// 7/ jumps to the user code with an eret. 
////////////////////////////////////////////////////////////////////////////////////

#include <common.h>
#include <irq_handler.h>
#include <ctx_handler.h>
#include <sys_handler.h>
#include <mapping_info.h>
#include <giet_config.h>
#include <mips32_registers.h>
#include <irq_handler.h>
#include <vm_handler.h>
#include <hwr_mapping.h>
#include <mwmr_channel.h>
#include <barrier.h>
#include <drivers.h>

///////////////////////////////////////////////////////////////////////////////////
// array of pointers on the page tables (both virtual and physical addresses)
///////////////////////////////////////////////////////////////////////////////////

__attribute__((section (".kdata"))) 
unsigned int _ptabs_paddr[GIET_NB_VSPACE_MAX]; 

__attribute__((section (".kdata"))) 
unsigned int _ptabs_vaddr[GIET_NB_VSPACE_MAX]; 

///////////////////////////////////////////////////////////////////////////////////
// array of pointers on the schedulers (physical addresses)
///////////////////////////////////////////////////////////////////////////////////

__attribute__((section (".kdata"))) 
static_scheduler_t * _schedulers_paddr[NB_CLUSTERS * NB_PROCS_MAX]; 

///////////////////////////////////////////////////////////////////////////////////
// staks for the "idle" tasks (256 bytes for each processor)
///////////////////////////////////////////////////////////////////////////////////

__attribute__((section (".kdata"))) 
unsigned int _idle_stack[NB_CLUSTERS*NB_PROCS_MAX * 64]; 

void _sys_exit() {
    while (1);
}


//////////////////////////////////////////////////////////////////////////////////
// This function is the entry point for the last step of the boot sequence.
//////////////////////////////////////////////////////////////////////////////////
__attribute__((section (".kinit"))) void _kernel_init() {
    // compute cluster and local processor index
    unsigned int global_pid = _procid();
    unsigned int cluster_id = global_pid / NB_PROCS_MAX;
    unsigned int proc_id = global_pid % NB_PROCS_MAX;

    // Step 0 : Compute number of tasks allocated to proc

    unsigned int tasks = _get_tasks_number();

#if GIET_DEBUG_INIT
    _get_lock(&_tty_put_lock);
    _puts("\n[GIET DEBUG] step 0 for processor ");
    _putd(global_pid);
    _puts(" : tasks = ");
    _putd(tasks);
    _puts("\n");
    _release_lock(&_tty_put_lock);
#endif

    // step 1 : Initialise scheduler physical addresses array
    //          get scheduler physical address (from CP0 register)

    static_scheduler_t * psched = (static_scheduler_t *) _get_sched();
    _schedulers_paddr[global_pid] = psched;

#if GIET_DEBUG_INIT
    _get_lock(&_tty_put_lock);
    _puts("\n[GIET DEBUG] step 1 for processor ");
    _putd(global_pid);
    _puts(" / scheduler pbase = ");
    _putx((unsigned int) psched);
    _puts("\n");
    _release_lock(&_tty_put_lock);
#endif

    // step 2 : initialise page table addresse arrays
    //          each processor scans all tasks contexts in its
    //          private scheduler and get VSID, PTAB and PTPR values

    unsigned int ltid;

    for (ltid = 0; ltid < tasks; ltid++) {
        unsigned int vspace_id = _get_context_slot(ltid , CTX_VSID_ID); 
        unsigned int ptab_vaddr = _get_context_slot(ltid , CTX_PTAB_ID); 
        unsigned int ptab_paddr = _get_context_slot(ltid , CTX_PTPR_ID) << 13; 

        _ptabs_vaddr[vspace_id] = ptab_vaddr;
        _ptabs_paddr[vspace_id] = ptab_paddr;

#if GIET_DEBUG_INIT
        _get_lock(&_tty_put_lock);
        _puts("\n[GIET DEBUG] step 2 for processor ");
        _putd(global_pid);
        _puts(" / vspace ");
        _putd(vspace_id);
        _puts("\n- ptab vbase = ");
        _putx(ptab_vaddr);
        _puts("\n- ptab pbase = ");
        _putx(ptab_paddr);
        _puts("\n");
        _release_lock(&_tty_put_lock);
#endif

    }

    unsigned int isr_switch_channel = 0xFFFFFFFF;

    // step 3 : compute and set ICU masks
    //          there is at most 32 interrupts per processor
    //          software interrupts are not supported yet

    unsigned int irq_id;
    unsigned int hwi_mask = 0;
    unsigned int pti_mask = 0;

    for (irq_id = 0; irq_id < 32; irq_id++) {
        unsigned int entry = _get_interrupt_vector_entry(irq_id);
        unsigned int isr = entry & 0x000000FF;

        if ((isr == ISR_DMA) || (isr == ISR_IOC) || (isr == ISR_TTY)) {
            hwi_mask = hwi_mask | 0x1 << irq_id;
        }
        else if ((isr == ISR_SWITCH)) { 
            pti_mask = pti_mask | 0x1 << irq_id;
            isr_switch_channel = irq_id;
        }
        else if ((isr == ISR_TIMER)) {
            pti_mask = pti_mask | 0x1 << irq_id;
        }
    }
    _icu_set_mask(cluster_id, proc_id, hwi_mask, 0); // set HWI_MASK
    _icu_set_mask(cluster_id, proc_id, pti_mask, 1); // set PTI_MASK

#if GIET_DEBUG_INIT
    _get_lock(&_tty_put_lock);
    _puts("\n[GIET DEBUG] step 3 for processor ");
    _putd(global_pid);
    _puts("\n - ICU HWI_MASK = ");
    _putx(hwi_mask);
    _puts("\n - ICU PTI_MASK = ");
    _putx(pti_mask);
    _puts("\n");
    _release_lock(&_tty_put_lock);
#endif

    // step 4 : start TICK timer if more than one task
    if (tasks > 1) {
        if (isr_switch_channel == 0xFFFFFFFF) {
            _get_lock(&_tty_put_lock);
            _puts("\n[GIET ERROR] ISR_SWITCH not found on proc ");
            _putd(proc_id);
            _puts("\n");
            _release_lock(&_tty_put_lock);
            _sys_exit();
        }

        if (_timer_start( cluster_id, isr_switch_channel, GIET_TICK_VALUE)) {
            _get_lock(&_tty_put_lock);
            _puts("\n[GIET ERROR] ISR_SWITCH init error for proc ");
            _putd(proc_id);
            _puts("\n");
            _release_lock(&_tty_put_lock);
            _sys_exit();
        }

#if GIET_DEBUG_INIT
        _get_lock(&_tty_put_lock);
        _puts("\n[GIET DEBUG] Step 4 for processor ");
        _putd(global_pid);
        _puts(" / context switch activated\n");
        _release_lock(&_tty_put_lock);
#endif

    } 

    // step 5 : initialise, for each processor, the "idle" task context:
    //          the SR initialisation value is 0xFF03 because
    //          the task _ctx_idle() executes in kernel mode.
    //          it uses the page table of vspace[0]
    //          the stack size is 256 bytes

    _set_context_slot( IDLE_TASK_INDEX, CTX_RUN_ID, 1);
    _set_context_slot( IDLE_TASK_INDEX, CTX_SR_ID,  0xFF03);
    _set_context_slot( IDLE_TASK_INDEX, CTX_SP_ID,  (unsigned int) _idle_stack + ((global_pid + 1) << 8));
    _set_context_slot( IDLE_TASK_INDEX, CTX_RA_ID,  (unsigned int) &_ctx_eret);
    _set_context_slot( IDLE_TASK_INDEX, CTX_EPC_ID, (unsigned int) &_ctx_idle);
    _set_context_slot( IDLE_TASK_INDEX, CTX_LTID_ID, IDLE_TASK_INDEX);
    _set_context_slot( IDLE_TASK_INDEX, CTX_PTPR_ID, _ptabs_paddr[0] >> 13);

#if GIET_DEBUG_INIT
    _get_lock(&_tty_put_lock);
    _puts("\n[GIET DEBUG] Step 5 for processor ");
    _putd(global_pid);
    _puts(" / idle task context set\n");
    _release_lock(&_tty_put_lock);
#endif

    // step 6 : each processor initialises SP, SR, PTPR, EPC, registers
    //          with the values corresponding to the first allocated task,
    //          and starts the "idle" task if there is no task allocated.

    unsigned int task_id;

    if (tasks == 0) {
        task_id = IDLE_TASK_INDEX;

        _get_lock(&_tty_put_lock);
        _puts("\n[GIET WARNING] No task allocated to processor ");
        _putd(global_pid);
        _puts(" => idle\n");
        _release_lock (&_tty_put_lock);
    }
    else {
        task_id = 0;
    }

    unsigned int sp_value = _get_context_slot(task_id, CTX_SP_ID);
    unsigned int sr_value = _get_context_slot(task_id, CTX_SR_ID);
    unsigned int ptpr_value = _get_context_slot(task_id, CTX_PTPR_ID);
    unsigned int epc_value = _get_context_slot(task_id, CTX_EPC_ID);

#if GIET_DEBUG_INIT
    _get_lock(&_tty_put_lock);
    _puts("\n[GIET DEBUG] step 6 for processor ");
    _putd(global_pid);
    _puts(" / registers initialised \n");
    _puts("- sp   = ");
    _putx(sp_value);
    _puts("\n");
    _puts("- sr   = ");
    _putx(sr_value);
    _puts("\n");
    _puts("- ptpr = ");
    _putx(ptpr_value << 13);
    _puts("\n");
    _puts("- epc  = ");
    _putx(epc_value);
    _puts("\n");
    _release_lock(&_tty_put_lock);
#endif

    // set  registers and jump to user code
    asm volatile (
            "move    $29,       %0    \n"        /* SP <= ctx[CTX_SP_ID] */
            "mtc0    %1,        $12   \n"        /* SR <= ctx[CTX_SR_ID] */
            "mtc2    %2,        $0    \n"        /* PTPR <= ctx[CTX_PTPR_ID] */
            "mtc0    %3,        $14   \n"        /* EPC <= ctx[CTX_EPC_ID] */
            "eret                     \n"        /* jump to user code */
            "nop                      \n"
            :
            : "r" (sp_value), "r" (sr_value), "r" (ptpr_value), "r" (epc_value));

} // end _kernel_init()

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