/*
 * linux/arch/ppc/kernel/traps.c
 *
 * Copyright (C) 1995-1996  Gary Thomas (gdt@linuxppc.org)
 *
 * Modified by Cort Dougan (cort@cs.nmt.edu)
 * and Paul Mackerras (paulus@cs.anu.edu.au)
 *
 * (C) Copyright 2000
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program 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; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

/*
 * This file handles the architecture-dependent parts of hardware exceptions
 */

#include <ppcboot.h>
#include <command.h>
#include <asm/processor.h>

#if (CONFIG_COMMANDS & CFG_CMD_KGDB)
int (*debugger_exception_handler)(struct pt_regs *) = 0;
#endif

/* Returns 0 if exception not found and fixup otherwise.  */
extern unsigned long search_exception_table(unsigned long);

/* THIS NEEDS CHANGING to use the board info structure.
*/
#define END_OF_MEM	0x00400000


static __inline__ void set_tsr(unsigned long val)
{
    asm volatile("mttsr %0" : : "r" (val));
}

static __inline__ unsigned long get_esr(void)
{
    unsigned long val;

    asm volatile("mfesr %0" : "=r" (val) :);
    return val;
}

#define ESR_MCI 0x80000000
#define ESR_PIL 0x08000000
#define ESR_PPR 0x04000000
#define ESR_PTR 0x02000000
#define ESR_DST 0x00800000
#define ESR_DIZ 0x00400000
#define ESR_U0F 0x00008000

#if (CONFIG_COMMANDS & CFG_CMD_BEDBUG)
extern void do_bedbug_breakpoint(struct pt_regs *);
#endif

/*
 * Trap & Exception support
 */

void
print_backtrace(unsigned long *sp)
{
	int cnt = 0;
	unsigned long i;

	printf("Call backtrace: ");
	while (sp) {
		if ((uint)sp > END_OF_MEM)
			break;

		i = sp[1];
		if (cnt++ % 7 == 0)
			printf("\n");
		printf("%08lX ", i);
		if (cnt > 32) break;
		sp = (unsigned long *)*sp;
	}
	printf("\n");
}

void show_regs(struct pt_regs * regs)
{
	int i;

	printf("NIP: %08lX XER: %08lX LR: %08lX REGS: %p TRAP: %04lx DAR: %08lX\n",
	       regs->nip, regs->xer, regs->link, regs, regs->trap, regs->dar);
	printf("MSR: %08lx EE: %01x PR: %01x FP: %01x ME: %01x IR/DR: %01x%01x\n",
	       regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
	       regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
	       regs->msr&MSR_IR ? 1 : 0,
	       regs->msr&MSR_DR ? 1 : 0);

	printf("\n");
	for (i = 0;  i < 32;  i++) {
		if ((i % 8) == 0)
		{
			printf("GPR%02d: ", i);
		}

		printf("%08lX ", regs->gpr[i]);
		if ((i % 8) == 7)
		{
			printf("\n");
		}
	}
}


void
_exception(int signr, struct pt_regs *regs)
{
	show_regs(regs);
	print_backtrace((unsigned long *)regs->gpr[1]);
	panic("Exception in kernel pc %lx signal %d",regs->nip,signr);
}

void
MachineCheckException(struct pt_regs *regs)
{
	unsigned long fixup;

	/* Probing PCI using config cycles cause this exception
	 * when a device is not present.  Catch it and return to
	 * the PCI exception handler.
	 */
	if ((fixup = search_exception_table(regs->nip)) != 0) {
		regs->nip = fixup;
		return;
	}

#if (CONFIG_COMMANDS & CFG_CMD_KGDB)
	if (debugger_exception_handler && (*debugger_exception_handler)(regs))
		return;
#endif

	printf("Machine check in kernel mode.\n");
	printf("Caused by (from msr): ");
	printf("regs %p ",regs);
	switch( regs->msr & 0x0000F000)
	{
	case (1<<12) :
		printf("Machine check signal - probably due to mm fault\n"
			"with mmu off\n");
		break;
	case (1<<13) :
		printf("Transfer error ack signal\n");
		break;
	case (1<<14) :
		printf("Data parity signal\n");
		break;
	case (1<<15) :
		printf("Address parity signal\n");
		break;
	default:
		printf("Unknown values in msr\n");
	}
	show_regs(regs);
	print_backtrace((unsigned long *)regs->gpr[1]);
	panic("machine check");
}

void
AlignmentException(struct pt_regs *regs)
{
#if (CONFIG_COMMANDS & CFG_CMD_KGDB)
	if (debugger_exception_handler && (*debugger_exception_handler)(regs))
		return;
#endif

	show_regs(regs);
	print_backtrace((unsigned long *)regs->gpr[1]);
	panic("Alignment Exception");
}

void
ProgramCheckException(struct pt_regs *regs)
{
        long esr_val;
  
#if (CONFIG_COMMANDS & CFG_CMD_KGDB)
	if (debugger_exception_handler && (*debugger_exception_handler)(regs))
		return;
#endif

	show_regs(regs);

        esr_val = get_esr();
        if( esr_val & ESR_PIL )
          printf( "** Illegal Instruction **\n" );
        else if( esr_val & ESR_PPR )
          printf( "** Privileged Instruction **\n" );
        else if( esr_val & ESR_PTR )
          printf( "** Trap Instruction **\n" );

	print_backtrace((unsigned long *)regs->gpr[1]);
	panic("Program Check Exception");
}

void
PITException(struct pt_regs *regs)
{
        /*
         * Reset PIT interrupt
         */
        set_tsr(0x08000000);

        /*
         * Call timer_interrupt routine in interrupts.c
         */
        timer_interrupt(NULL);
}


void
UnknownException(struct pt_regs *regs)
{
#if (CONFIG_COMMANDS & CFG_CMD_KGDB)
	if (debugger_exception_handler && (*debugger_exception_handler)(regs))
		return;
#endif

	printf("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
	       regs->nip, regs->msr, regs->trap);
	_exception(0, regs);
}

void
DebugException(struct pt_regs *regs)
{
  printf("Debugger trap at @ %lx\n", regs->nip );
  show_regs(regs);
#if (CONFIG_COMMANDS & CFG_CMD_BEDBUG)
  do_bedbug_breakpoint( regs );
#endif
}

/* Probe an address by reading.  If not present, return -1, otherwise
 * return 0.
 */
int
addr_probe(uint *addr)
{
#if 0
	int	retval;

	__asm__ __volatile__(			\
		"1:	lwz %0,0(%1)\n"		\
		"	eieio\n"		\
		"	li %0,0\n"		\
		"2:\n"				\
		".section .fixup,\"ax\"\n"	\
		"3:	li %0,-1\n"		\
		"	b 2b\n"			\
		".section __ex_table,\"a\"\n"	\
		"	.align 2\n"		\
		"	.long 1b,3b\n"		\
		".text"				\
		: "=r" (retval) : "r"(addr));

	return (retval);
#endif
	return 0;
}
