vectors.s

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##=============================================================================
##
##	vectors.S
##
##	MIPS exception vectors
##
##=============================================================================
#####ECOSGPLCOPYRIGHTBEGIN####
## -------------------------------------------
## This file is part of eCos, the Embedded Configurable Operating System.
## Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
##
## eCos 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 or (at your option) any later version.
##
## eCos 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 eCos; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
##
## As a special exception, if other files instantiate templates or use macros
## or inline functions from this file, or you compile this file and link it
## with other works to produce a work based on this file, this file does not
## by itself cause the resulting work to be covered by the GNU General Public
## License. However the source code for this file must still be made available
## in accordance with section (3) of the GNU General Public License.
##
## This exception does not invalidate any other reasons why a work based on
## this file might be covered by the GNU General Public License.
##
## Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
## at http://sources.redhat.com/ecos/ecos-license/
## -------------------------------------------
#####ECOSGPLCOPYRIGHTEND####
##=============================================================================
#######DESCRIPTIONBEGIN####
##
## Author(s): 	nickg
## Contributors:	nickg, dmoseley
## Date:	1998-02-04
## Purpose:	MIPS exception vectors
## Description:	This file defines the code placed into the exception
##              vectors. It also contains the first level default VSRs
##		that save and restore state for both exceptions and
##		interrupts.
##
######DESCRIPTIONEND####
##
##=============================================================================

#include <pkgconf/system.h>	
#include <pkgconf/hal.h>

#ifdef CYGPKG_KERNEL
# include <pkgconf/kernel.h>	
#endif
			
#include <cyg/hal/arch.inc>	
#include <cyg/hal/hal_arch.h>	
	
#ifdef at
#undef at
#endif
	.extern cyg_instrument

##-----------------------------------------------------------------------------
## Hardware supplied vectors
	
	.set	noreorder

	.section ".reset_vector","ax"

	# Reset vector at 0xBFC00000

FUNC_START(reset_vector)

#ifndef CYG_HAL_STARTUP_RAM
#  if defined(CYGPKG_HAL_RESET_VECTOR_FIRST_CODE)
	hal_reset_vector_first_code
#  endif
#  if defined(CYGPKG_HAL_EARLY_INIT)
	hal_early_init
#  endif
	# Decide whether this is an NMI, cold or warm boot.

	mfc0	k0,status		# get status reg
	lui	k1,0x0008		# isolate NMI bit
	and	k1,k1,k0		
	beqz	k1,1f			# skip if zero
	nop

	lar	k1,__nmi_entry		# jump to ROM nmi code
	jalr	k1
	nop
1:
	lui	k1,0x0010		# isolate soft reset bit
	and	k1,k1,k0		
	beqz	k1,2f			# skip if zero
	nop

	lar	k1,__warm_start		# jump to ROM warm_start code
	jr	k1
	nop
2:
	la	k0,INITIAL_CONFIG0	# Set up config0 register
	mtc0	k0,config0		# to disable cache
#endif	
	lar	v0,_start		# jump to start
#ifdef CYGARC_START_FUNC_UNCACHED
	CYGARC_ADDRESS_REG_UNCACHED(v0)
#endif

	jr	v0
	nop				# (delay slot)

FUNC_END(reset_vector)
	
	.section ".debug_vector","ax"
		
	# Debug vector at 0xBFC00200
	
FUNC_START(debug_vector)
	la	k0,32*4
	la	k1,hal_vsr_table	# Get VSR table
	lw	k1,32*4(k1)		# load debug vector
	jr	k1			# go there
	nop				# (delay slot)
FUNC_END(debug_vector)

	.section ".other_vector","ax"

	# Common vector at 0x80000080 or 0xBFC00180
	
FUNC_START(other_vector)
	mfc0	k0,cause		# K0 = exception cause
	nop
	andi	k0,k0,0x7F		# isolate exception code
	la	k1,hal_vsr_table	# address of VSR table
	add	k1,k1,k0		# offset of VSR entry
	lw	k1,0(k1)		# k1 = pointer to VSR
	jr	k1			# go there
	nop				# (delay slot)
FUNC_END(other_vector)
	
	.section ".utlb_vector","ax"

FUNC_START(utlb_vector)
	mfc0	k0,cause		# K0 = exception cause
	nop
	andi	k0,k0,0x7F		# isolate exception code
	la	k1,hal_vsr_table	# address of VSR table
	add	k1,k1,k0		# offset of VSR entry
	lw	k1,0(k1)		# k1 = pointer to VSR
	jr	k1			# go there
	nop				# (delay slot)
FUNC_END(utlb_vector)

##-----------------------------------------------------------------------------
## Startup code

	.text
	
FUNC_START(_start)

	# Initialize hardware
	hal_cpu_init
	hal_diag_init
	hal_mmu_init
	hal_fpu_init
	hal_memc_init
	hal_intc_init
	hal_cache_init
	hal_timer_init
			
#ifdef CYGARC_START_FUNC_UNCACHED
	# switch to cached execution address if necessary
	# assumption is that hal_cache_init makes this safe
	lar	v0,1f
	jr	v0
	nop
   1:
#endif
	
	# Load Global Pointer register.
	la	gp,_gp

	# load initial stack pointer
	la	a0,__interrupt_stack
	move	sp,a0

	hal_mon_init
		
#ifdef CYG_HAL_STARTUP_ROM
	# Copy data from ROM to RAM

	.extern	hal_copy_data
	jal	hal_copy_data
	nop

#endif

	# Zero BSS

	.extern hal_zero_bss
	jal	hal_zero_bss
	nop

	# Call variant and platform HAL
	# initialization routines.

	.extern	hal_variant_init
	jal	hal_variant_init
	nop

	.extern	hal_platform_init
	jal	hal_platform_init
	nop

	# Call constructors
	.extern cyg_hal_invoke_constructors
	jal     cyg_hal_invoke_constructors
	nop

#if defined(CYGDBG_HAL_DEBUG_GDB_INCLUDE_STUBS)
        .extern initialize_stub
        jal     initialize_stub
        nop
#endif
#if defined(CYGDBG_HAL_MIPS_DEBUG_GDB_CTRLC_SUPPORT)
        .extern hal_ctrlc_isr_init
        jal     hal_ctrlc_isr_init
        nop
#endif

	# Call cyg_start	
	
	.extern	cyg_start
	j	cyg_start
        lui     ra,0
	
FUNC_END(_start	)


##-----------------------------------------------------------------------------
		
FUNC_START(__warm_start)

	## The following is debug code left in here for now in case it
	## proves useful in the near future.	
#if 0
	move	s0,t0
	move	s1,a1
	
#	hal_diag_init

	hal_diag_writec '$'
	mvafc0	a0,$30			# get ErrorEPC
	lar	k0,hal_diag_ai_write_hex8
	jalr	k0
	nop
	hal_diag_writec '-'	
	move	a0,s0
	jalr	k0
	nop
	hal_diag_writec '-'	
	move	a0,s1
	jalr	k0
	nop
1:	
	b	1b
	nop
#endif

	# Treat a warm-start either as a cold-start or an NMI
#if defined(CYGHWR_HAL_MIPS_WARMSTART_COLDSTART)
	lar	v0,_start		# jump to start
	jr	v0
	nop				# (delay slot)
#else
        # Defaults to NMI
	b	__nmi_entry
	nop
#endif        

FUNC_END(__warm_start)		

##-----------------------------------------------------------------------------
	
FUNC_START(__nmi_entry)		

	# Clear exception state
	hal_cpu_except_enable
	
	# Move the ErrorEPC register to the EPC register so that the
	# default exception handler saves the right PC value.
	mvafc0	k0,$30
	nop; nop; nop;
	mvatc0	k0,epc
	nop; nop; nop;	

#if (INITIAL_SR & 0x00400000) == 0
	# Taking this exception will have set the BEV bit to 1.
	# If we normally run with it zero, we must clear it here.
	mfc0	k0,status	
	la	k1,0xFFBFFFFF
	and	k0,k0,k1
	mtc0	k0,status
#endif	

	la	k0,34*4
	la	k1,hal_vsr_table	# Get VSR table
	lw	k1,34*4(k1)		# load NMI vector
	jr	k1			# go there
	nop				# (delay slot)
	
FUNC_END(__nmi_entry)

##-----------------------------------------------------------------------------
## Default exception VSR.
## Saves machine state and calls external handling code.
	
FUNC_START(__default_exception_vsr)

	# We enter here with all of the CPU state still
	# in its registers except:
	# K0 = vector index
	# K1 = address of this function

	move	k1,sp			# K1 = original SP
	
	addi	sp,sp,-mips_exception_decrement
				# space for registers + safety margin

	sw	k0,mipsreg_vector(sp)	# store vector

	# store GPRs
	.set	noat
	sgpr	0,sp
	sgpr	1,sp
	sgpr	2,sp
	sgpr	3,sp
	sgpr	4,sp
	sgpr	5,sp
	sgpr	6,sp
	sgpr	7,sp
	sgpr	8,sp
	sgpr	9,sp
	sgpr	10,sp
	sgpr	11,sp
	sgpr	12,sp
	sgpr	13,sp
	sgpr	14,sp
	sgpr	15,sp
	sgpr	16,sp
	sgpr	17,sp
	sgpr	18,sp
	sgpr	19,sp
	sgpr	20,sp
	sgpr	21,sp
	sgpr	22,sp
	sgpr	23,sp
	sgpr	24,sp
	sgpr	25,sp
#	sgpr	26,sp	# == K0
#	sgpr	27,sp	# == K1
	sgpr	28,sp	# == GP
#	sgpr	29,sp	# == SP
	sgpr	30,sp	# == FP
	sgpr	31,sp	# == RA
	.set	at
	
	mfhi	a0
	mflo	a1
	shi	a0,sp
	slo	a1,sp

	# K1 contains original SP
	ssp	k1,sp			# store in reg dump	
	
	# save remaining machine state registers	
	mfc0	t0,cause
	mfc0	t1,status
	mfc0	t2,cachectrl
	mvafc0	t3,badvr
	mfc0	t4,config
	mfc0	t5,prid
	mvafc0	t6,epc
	
	sw	t0,mipsreg_cause(sp)
	sw	t1,mipsreg_sr(sp)
	sw	t2,mipsreg_cachectrl(sp)
	sva	t3,mipsreg_badvr(sp)
	sw	t4,mipsreg_config(sp)
	sw	t5,mipsreg_prid(sp)
	sva	t6,mipsreg_pc(sp)

	hal_fpu_save sp
	
	# The machine state is now all saved on the stack.

	hal_diag_excpt_start
	
	# Load Global Pointer register.
	la	gp,_gp
	
	move	s0,sp				# save pointer to saved state

#if defined(CYGSEM_HAL_ROM_MONITOR) && \
    defined(CYGIMP_HAL_COMMON_INTERRUPTS_USE_INTERRUPT_STACK)

	la	a0,__interrupt_stack		# a0 = stack top
	la	a1,__interrupt_stack_base	# a1 = stack base
	sub	a3,sp,a1			# a3 = sp - base
	bltz	a3,1f				# not on istack if < 0 
	nop					# delay slot
	sub	t0,a0,sp			# t0 = top - sp
	bgtz	t0,8f				# already on istack if > 0 
	nop					# delay slot
1:	
	move	sp,a0				# switch to istack
8:
	addi	sp,sp,-8			# space for old SP 
						# (8 to keep dword alignment!)
	sw	s0,0(sp)			# save old SP on stack
	
#endif		
	addi	sp,sp,-mips_stack_frame_size	# make a null frame	

	# Need to set up back pointers etc. ???

	hal_cpu_except_enable			# reenable exceptions

	.extern	cyg_hal_exception_handler
	jal	cyg_hal_exception_handler	# call C code
	move	a0,s0				# arg0 = register dump (delay slot)
		
#if defined(CYGSEM_HAL_ROM_MONITOR) && \
    defined(CYGIMP_HAL_COMMON_INTERRUPTS_USE_INTERRUPT_STACK)

	# If we are returning from the last nested exception, move back
	# to the thread stack.
	# Since we have arranged for the top of stack location to
	# contain the sp we need to go back to here, just pop it off
	# and put it in SP.

	lw	sp,mips_stack_frame_size(sp)	# sp = *sp
	subu	sp,sp,mips_stack_frame_size	# make a null frame		
#endif
	
	j	restore_state
	nop
				
FUNC_END(__default_exception_vsr)

##------------------------------------------------------------------------------
## Default interrupt VSR.
## Saves machine state and calls appropriate ISR. When done, calls
## interrupt_end() to finish up and possibly reschedule.	

FUNC_START(__default_interrupt_vsr)

	
	# We enter here with all of the CPU state still
	# in its registers except:
	# K0 = vector index
	# K1 = address of this function

	move	k1,sp			# K1 = original SP
		
	addi	sp,sp,-mips_exception_decrement
				# space for registers + safety margin

	sw	k0,mipsreg_vector(sp)	# store vector

	# store GPRs
	.set	noat
	sgpr	0,sp
	sgpr	1,sp
	sgpr	2,sp
	sgpr	3,sp
	sgpr	4,sp
	sgpr	5,sp
	sgpr	6,sp
	sgpr	7,sp
	sgpr	8,sp
	sgpr	9,sp
	sgpr	10,sp
	sgpr	11,sp
	sgpr	12,sp
	sgpr	13,sp
	sgpr	14,sp
	sgpr	15,sp
	sgpr	16,sp
	sgpr	17,sp
	sgpr	18,sp
	sgpr	19,sp
	sgpr	20,sp
	sgpr	21,sp
	sgpr	22,sp
	sgpr	23,sp
	sgpr	24,sp
	sgpr	25,sp
#	sgpr	26,sp	# == K0
#	sgpr	27,sp	# == K1
	sgpr	28,sp	# == GP
#	sgpr	29,sp	# == SP
	sgpr	30,sp	# == FP