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/*
 * Copyright (C) 2003-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <arch/exception.h>
#include <arch/interrupt.h>
#include <panic.h>
#include <arch/cp0.h>
#include <arch/types.h>
#include <arch.h>
#include <debug.h>
#include <proc/thread.h>
#include <symtab.h>
#include <print.h>
#include <interrupt.h>
#include <func.h>
#include <console/kconsole.h>
#include <arch/debugger.h>

static char * exctable[] = {
    "Interrupt","TLB Modified","TLB Invalid","TLB Invalid Store",
        "Address Error - load/instr. fetch",
        "Address Error - store",
        "Bus Error - fetch instruction",
        "Bus Error - data reference",
        "Syscall",
        "BreakPoint",
        "Reserved Instruction",
        "Coprocessor Unusable",
        "Arithmetic Overflow",
        "Trap",
        "Virtual Coherency - instruction",
        "Floating Point",
        NULL, NULL, NULL, NULL, NULL, NULL, NULL,
        "WatchHi/WatchLo", /* 23 */
        NULL, NULL, NULL, NULL, NULL, NULL, NULL,
        "Virtual Coherency - data",
};

static void print_regdump(struct exception_regdump *pstate)
{
    char *pcsymbol = "";
    char *rasymbol = "";

    char *s = get_symtab_entry(pstate->epc);
    if (s)
        pcsymbol = s;
    s = get_symtab_entry(pstate->ra);
    if (s)
        rasymbol = s;
    
    printf("PC: %X(%s) RA: %X(%s)\n",pstate->epc,pcsymbol,
           pstate->ra,rasymbol);
}

static void unhandled_exception(int n, void *data)
{
    struct exception_regdump *pstate = (struct exception_regdump *)data;

    print_regdump(pstate);
    panic("unhandled exception %s\n", exctable[n]);
}

static void breakpoint_exception(int n, void *data)
{
    struct exception_regdump *pstate = (struct exception_regdump *)data;

#ifdef CONFIG_DEBUG
    debugger_bpoint(pstate);
#else
    /* it is necessary to not re-execute BREAK instruction after 
       returning from Exception handler
       (see page 138 in R4000 Manual for more information) */
    pstate->epc += 4;
#endif
}

static void tlbmod_exception(int n, void *data)
{
    struct exception_regdump *pstate = (struct exception_regdump *)data;
    tlb_modified(pstate);
}

static void tlbinv_exception(int n, void *data)
{
    struct exception_regdump *pstate = (struct exception_regdump *)data;
    tlb_invalid(pstate);
}

#ifdef CONFIG_FPU_LAZY
static void cpuns_exception(int n, void *data)
{
    if (cp0_cause_coperr(cp0_cause_read()) == fpu_cop_id)
        scheduler_fpu_lazy_request();
    else
        panic("unhandled Coprocessor Unusable Exception\n");
}
#endif

static void interrupt_exception(int n, void *pstate)
{
    __u32 cause;
    int i;
    
    /* decode interrupt number and process the interrupt */
    cause = (cp0_cause_read() >> 8) &0xff;
    
    for (i = 0; i < 8; i++)
        if (cause & (1 << i))
            exc_dispatch(i+INT_OFFSET, pstate);
}


void exception(struct exception_regdump *pstate)
{
    int cause;
    int excno;

    ASSERT(CPU != NULL);

    /*
     * NOTE ON OPERATION ORDERING
     *
     * On entry, interrupts_disable() must be called before 
     * exception bit is cleared.
     */

    interrupts_disable();
    cp0_status_write(cp0_status_read() & ~ (cp0_status_exl_exception_bit |
                        cp0_status_um_bit));

    /* Save pstate so that the threads can access it */
    /* If THREAD->pstate is set, this is nested exception,
     * do not rewrite it
     */
    if (THREAD && !THREAD->pstate)
        THREAD->pstate = pstate;

    cause = cp0_cause_read();
    excno = cp0_cause_excno(cause);
    /* Dispatch exception */
    exc_dispatch(excno, pstate);

    /* Set to NULL, so that we can still support nested
     * exceptions
     * TODO: We should probably set EXL bit before this command,
     * nesting. On the other hand, if some exception occurs between
     * here and ERET, it won't set anything on the pstate anyway.
     */
    if (THREAD)
        THREAD->pstate = NULL;
}

void exception_init(void)
{
    int i;

    /* Clear exception table */
    for (i=0;i < IVT_ITEMS; i++)
        exc_register(i, "undef", unhandled_exception);
    exc_register(EXC_Bp, "bkpoint", breakpoint_exception);
    exc_register(EXC_Mod, "tlb_mod", tlbmod_exception);
    exc_register(EXC_TLBL, "tlbinvl", tlbinv_exception);
    exc_register(EXC_TLBS, "tlbinvl", tlbinv_exception);
    exc_register(EXC_Int, "interrupt", interrupt_exception);
#ifdef CONFIG_FPU_LAZY
    exc_register(EXC_CpU, "cpunus", cpuns_exception);
#endif
}