Subversion Repositories openrisc

##==========================================================================

##

##      vectors.S

##

##      PowerPC exception vectors

##

##==========================================================================

#####ECOSGPLCOPYRIGHTBEGIN####

## -------------------------------------------

## This file is part of eCos, the Embedded Configurable Operating System.

## Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

## Copyright (C) 2002 Gary Thomas

##

## 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, jskov

## Contributors: nickg, jskov

## Date:         1999-02-20

## Purpose:      PowerPC 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####

##

##==========================================================================

#===========================================================================

#

#       The PowerPC exception handling has changed as of version 1.3.1.

#       The primary motivation for rewriting the code was to bring it more

#       in line with the other HALs, in particular to allow a RAM application

#       to cleanly take over only a subset of vectors from a running ROM

#       monitor.

#

#       GDB stubs (and CygMon, should it be ported to PPC) copies

#       exception vector entry handler code to address 0. These vector entry

#       handlers (defined by the exception_vector macro below) compute

#       a vector index into the hal_vsr_table, fetch the pointer, and

#       jump to the HAL vector service routine (VSR).

#

#       The hal_vsr_table is located immediately after the vector

#       handlers (at address 0x3000), allowing RAM applications to

#       change VSRs as necessary, while still keeping desired ROM

#       monitor functionality available for debugging.

#

#       ROM applications can still be configured to leave the vector entry

#       handlers at 0xff000000, but there is at the moment no

#       provision for reclaiming the reserved vector space in RAM to

#       application usage.

#

#       RAM applications can also be configured to provide exception

#       handlers which are copied to address 0 on startup, thus taking

#       full control of the target.

#

#

#       Default configuration is for RAM applications to rely on an

#       existing ROM monitor to provide debugging functionality, and

#       for ROM applications to copy vectors to address 0.

#

#

#       Unfortunately the new exception scheme is not compatible with the

#       old scheme. Stubs and applications must be compiled using the same

#       scheme (i.e., old binaries will not run with new stubs, and new

#       binaries will not run with old stubs).

#

#===========================================================================

#include 

#ifdef CYGPKG_KERNEL

#include      // CYGPKG_KERNEL_INSTRUMENT

#endif

#define CYGARC_HAL_COMMON_EXPORT_CPU_MACROS

#include 

#===========================================================================

//        .file   "vectors.S"

        .extern hal_interrupt_data

        .extern hal_interrupt_handlers

        .extern hal_interrupt_objects

        .extern hal_vsr_table

        .extern cyg_hal_invoke_constructors

        .extern cyg_instrument

        .extern cyg_start

        .extern hal_IRQ_init

        .extern hal_MMU_init

        .extern hal_enable_caches

        .extern hal_hardware_init

        .extern initialize_stub

        .extern __bss_start

        .extern __bss_end

        .extern __sbss_start

        .extern __sbss_end

#===========================================================================

# MSR initialization value

# zero all bits except:

# FP = floating point available

# ME = machine check enabled

# IP = vectors at 0xFFFxxxxx (ROM startup only)

# IR = instruction address translation

# DR = data address translation

# RI = recoverable interrupt

#define CYG_MSR_COMMON (MSR_FP | MSR_ME | MSR_RI)

#if (CYGHWR_HAL_POWERPC_VECTOR_BASE == 0xfff00000)

# define IP_BIT MSR_IP

#else

# define IP_BIT 0

#endif

#ifdef CYGHWR_HAL_POWERPC_ENABLE_MMU

# define IR_DR_BITS (MSR_IR | MSR_DR)

#else

# define IR_DR_BITS 0

#endif

#define CYG_MSR (CYG_MSR_COMMON | IP_BIT | IR_DR_BITS)

# Include variant macros after MSR definition.

#include 

#include 

#===========================================================================

# If the following option is enabled, we only save registers up to R12.

# The PowerPC ABI defines registers 13..31 as callee saved and thus we do

# not need to save them when calling C functions.

#ifdef CYGDBG_HAL_COMMON_INTERRUPTS_SAVE_MINIMUM_CONTEXT

# define MAX_SAVE_REG    12

#else

# define MAX_SAVE_REG    31

#endif

#if defined(CYGHWR_HAL_POWERPC_NEED_VECTORS)

#===========================================================================

# Start by defining the exceptions vectors that must be placed at

# locations 0xFFF00000 or 0x00000000. The following code will normally

# be located at 0xFFF00000 in the ROM. It may optionally be copied out

# to 0x00000000 if we want to use the RAM vectors. For this reason this code

# MUST BE POSITION INDEPENDENT.

        .section ".vectors","ax"

#---------------------------------------------------------------------------

# Macros for generating an exception vector service routine

# Reset vector macro

        .macro  reset_vector name

        .p2align 8

        .globl  __exception_\name

__exception_\name:

#ifdef CYGSEM_HAL_POWERPC_RESET_USES_JUMP

        bl      _start

#else

        lwi     r3,_start

        mtlr    r3

        blr

#endif

        .endm

# Generic vector macro

        .macro  exception_vector name

        .p2align 8

        .globl  __exception_\name

__exception_\name:

        mtspr   SPRG1,r3                     # stash some work registers away

        mtspr   SPRG2,r4

        mtspr   SPRG3,r5

        mfcr    r4                           # stash CR

        li      r5,__exception_\name-rom_vectors       # load low half of vector addr

        srwi    r5,r5,6                      # shift right by 6

        lwi     r3,hal_vsr_table             # table base

        lwzx    r3,r3,r5                     # address of vsr

        mflr    r5                           # save link register

        mtlr    r3                           # put vsr address into it

        li      r3,__exception_\name-rom_vectors       # reload low half of vector addr

        blr                                  # go to common code

        .endm

#---------------------------------------------------------------------------

# Define the exception vectors.

// Some platforms won't let us put the vector code just where we want

// This macro introduces some lattitude in vector placement

#ifdef CYG_HAL_FUDGE_VECTOR_ALIGNMENT

        hal_fudge_vector_alignment

#endif

rom_vectors:

        # These are the architecture defined vectors that

        # are always present.

#ifdef CYG_HAL_RESERVED_VECTOR_00000

        hal_reserved_vector_00000

#else

        exception_vector        reserved_00000

#endif

        reset_vector            reset

        exception_vector        machine_check

        exception_vector        data_storage

        exception_vector        instruction_storage

        exception_vector        external

        exception_vector        alignment

        exception_vector        program

        exception_vector        floatingpoint_unavailable

        exception_vector        decrementer

        exception_vector        reserved_00a00

        exception_vector        reserved_00b00

        exception_vector        system_call

        exception_vector        trace

        exception_vector        floatingpoint_assist

        exception_vector        reserved_00f00

        # Variants may define extra vectors.

        hal_extra_vectors

rom_vectors_end:

#else //  CYGHWR_HAL_POWERPC_NEED_VECTORS

        # When vectors are not included this is the primary entry point.

        .globl  __exception_reset

__exception_reset:

        lwi     r3,_start

        mtlr    r3

        blr

#endif //  CYGHWR_HAL_POWERPC_NEED_VECTORS

#===========================================================================

# Real startup code. We jump here from the various reset vectors to set up

# the world.

        .text

        .globl  _start

_start:

        # Initialize CPU to a post-reset state, ensuring the ground doesn''t

        # shift under us while we try to set things up.

        hal_cpu_init

        # Set up global offset table

        lwi     r2,_GLOBAL_OFFSET_TABLE_

        # set up time base register to zero

        xor     r3,r3,r3

        mtspr   TBL_W,r3

        xor     r4,r4,r4

        mtspr   TBU_W,r4

        # Call platform specific hardware initialization

        # This may include memory controller initialization. It is not

        # safe to access RAM until after this point.

        bl      hal_hardware_init       # this is platform dependent

        .globl  _hal_hardware_init_done

_hal_hardware_init_done:

#if !defined(CYG_HAL_STARTUP_ROM) && defined(CYGSEM_HAL_POWERPC_COPY_VECTORS)

        lwi     r3,rom_vectors-4

        lwi     r4,(CYGHWR_HAL_POWERPC_VECTOR_BASE - 4)

        lwi     r5,rom_vectors_end-4

0:      lwzu    r0,4(r3)

        stwu    r0,4(r4)

        cmplw   r3,r5

        bne     0b

#endif

        # set up stack

        lwi     sp,__interrupt_stack

        mtspr   SPRG0,sp        # save in sprg0 for later use

        # Set up exception handlers and VSR table, taking care not to

        # step on any ROM monitor''s toes.

        hal_mon_init

#if defined(CYG_HAL_STARTUP_ROM)

        # Copy data from ROM to ram

        lwi     r3,__rom_data_start     # r3 = rom start

        lwi     r4,__ram_data_start     # r4 = ram start

        lwi     r5,__ram_data_end       # r5 = ram end

        cmplw   r4,r5                   # skip if no data

        beq     2f

1:

        lwz     r0,0(r3)                # get word from ROM

        stw     r0,0(r4)                # store in RAM

        addi    r3,r3,4                 # increment by 1 word

        addi    r4,r4,4                 # increment by 1 word

        cmplw   r4,r5                   # compare

        blt     1b                      # loop if not yet done

2:

#endif

        # clear BSS

        lwi     r3,__bss_start  # r3 = start

        lwi     r4,__bss_end    # r4 = end

        li      r0,0            # r0 = 0

        cmplw   r3,r4           # skip if no bss

        beq     2f

1:      stw     r0,0(r3)        # store zero

        addi    r3,r3,4         # increment by 1 word

        cmplw   r3,r4           # compare

        blt     1b              # loop if not yet done

2:

        # clear SBSS

        lwi     r3,__sbss_start # r3 = start

        lwi     r4,__sbss_end   # r4 = end

        cmplw   r3,r4           # skip if no sbss

        beq     2f

1:      stw     r0,0(r3)        # store zero

        addi    r3,r3,4         # increment by 1 word

        cmplw   r3,r4           # compare

        blt     1b              # loop if not yet done

2:

        # It is now safe to call C functions which may rely on initialized

        # data.

        # Set up stack for calls to C code.

        subi    sp,sp,12                        # make space on stack

        li      r0,0

        stw     r0,0(sp)                        # clear back chain

        stw     r0,8(sp)                        # zero return pc

        stwu    sp,-CYGARC_PPC_STACK_FRAME_SIZE(sp) # create new stack frame

        # Variant HALs may need to do something special before we continue

        bl      hal_variant_init

        # Platform initialization

        bl      hal_platform_init

        # MMU and cache are controlled by the same option since caching

        # on the PPC does not make sense without the MMU to mark regions

        # which should not be cached.

#ifdef CYGHWR_HAL_POWERPC_ENABLE_MMU

        # Initialize MMU.

        bl      hal_MMU_init

        # Enable MMU so we can safely enable caches.

        lwi     r3,CYG_MSR              # interrupts enabled later

        sync

        mtmsr   r3

        sync

        # Enable caches

        bl      hal_enable_caches

#endif // CYGHWR_HAL_POWERPC_ENABLE_MMU

        # set up platform specific interrupt environment

        bl      hal_IRQ_init

        # call c++ constructors

        bl      cyg_hal_invoke_constructors

#ifdef CYGDBG_HAL_DEBUG_GDB_INCLUDE_STUBS

        bl      initialize_stub

#endif

#if defined(CYGDBG_HAL_DEBUG_GDB_CTRLC_SUPPORT) \

    || defined(CYGDBG_HAL_DEBUG_GDB_BREAK_SUPPORT)

        .extern hal_ctrlc_isr_init

        bl     hal_ctrlc_isr_init

#endif

        bl      cyg_start                       # call cyg_start

9:

        b       9b              # if we return, loop

#---------------------------------------------------------------------------

# This code handles the common part of all exception handlers.

# It saves the machine state onto the stack  and then calls

# a "C" routine to do the rest of the work. This work may result

# in thread switches, and changes to the saved state. When we return

# here the saved state is restored and execution is continued.

        .text

        .globl cyg_hal_default_exception_vsr

cyg_hal_default_exception_vsr:

        # We come here with all register containing their

        # pre-exception values except:

        # R3    = ls 16 bits of vector address

        # R4    = saved CR

        # R5    = saved LR

        # LR    = VSR address

        # SPRG1 = old R3

        # SPRG2 = old R4

        # SPRG3 = old R5

        # SRR0  = old PC

        # SRR1  = old MSR and the exception cause (the POW state is lost!)

        subi    sp,sp,CYGARC_PPC_EXCEPTION_DECREMENT

                                        # leave space for registers and

                                        # a safety margin

#ifdef CYGPKG_HAL_POWERPC_PPC40x

// The caches on this processor are always enabled when the MMU is on

// (and disabled when off).  Thus we need to be careful about cache

// polution and staleness when changing the MMU state.

// At this point, the MMU is off due to the exception.  We need to

// flush the part of the cache which may be touched before the MMU

// is reenabled so that memory will be consistent when that happens.

// Of course, this is complicated by the fact that there are no "free"

// registers at this point in the code.

        dcbf    0,sp                    // Flushes first line

        stw     r3,0(sp)                // This is now safe

        li      r3,CYGARC_PPCREG_VECTOR // Flush lines which will be changed

        dcbf    r3,sp

        li      r3,CYGARC_PPCREG_CR

        dcbf    r3,sp

        li      r3,CYGARC_PPCREG_LR

        dcbf    r3,sp

        lwz     r3,0(sp)                // Restore register

#endif

        # First, save away some registers

        stw     r3,CYGARC_PPCREG_VECTOR(sp)    # stash vector

        stw     r4,CYGARC_PPCREG_CR(sp)        # stash CR

        stw     r5,CYGARC_PPCREG_LR(sp)        # stash LR

#ifdef CYGDBG_HAL_POWERPC_FRAME_WALLS

        # Mark this fram as an Exception frame

        lwi     r3,0xDDDDDDE0

        stw     r3,CYGARC_PPCREG_WALL_HEAD(sp)

        lwi     r3,0xDDDDDDE1

        stw     r3,CYGARC_PPCREG_WALL_TAIL(sp)

#endif

        # Enable MMU.

        lwi     r3,CYG_MSR

        sync

        mtmsr   r3

        sync

        mfspr   r3,SPRG1                # save original R3

        stw     r3,CYGARC_PPCREG_REGS+3*4(sp)

        mfspr   r4,SPRG2                # save original R4

        stw     r4,CYGARC_PPCREG_REGS+4*4(sp)

        mfspr   r5,SPRG3                # save original R5

        stw     r5,CYGARC_PPCREG_REGS+5*4(sp)

        stw     r0,CYGARC_PPCREG_REGS+0*4(sp)  # save R0

        stw     r2,CYGARC_PPCREG_REGS+2*4(sp)  # save R2

        mr      r3,sp                   # recreate original SP

        addi    r3,r3,CYGARC_PPC_EXCEPTION_DECREMENT

        stw     r3,CYGARC_PPCREG_REGS+1*4(sp)  # and save it in state

        # Save registers r6..r12/r31

        .set    _reg,6

        .rept   MAX_SAVE_REG+1-6

        stw     _reg,(CYGARC_PPCREG_REGS+_reg*4)(sp)

        .set    _reg,_reg+1

        .endr

        # Save registers used in vsr (r14+r15)

        stw     r14,(CYGARC_PPCREG_REGS+14*4)(sp)

        stw     r15,(CYGARC_PPCREG_REGS+15*4)(sp)

        # get remaining family CPU registers

        mfxer   r3

        mfctr   r4

        mfsrr0  r5

        mfsrr1  r6

        # and store them

        stw     r3,CYGARC_PPCREG_XER(sp)

        stw     r4,CYGARC_PPCREG_CTR(sp)

        stw     r5,CYGARC_PPCREG_PC(sp)

        stw     r6,CYGARC_PPCREG_MSR(sp)

        # Save variant registers

        hal_variant_save sp

        # Save FPU registers

        hal_fpu_save sp

        # The entire CPU state is now stashed on the stack,

        # call into C to do something with it.

        mr      r3,sp                           # R3 = register dump

        subi    sp,sp,CYGARC_PPC_STACK_FRAME_SIZE # make a null frame

        li      r0,0                            # R0 = 0

        stw     r0,0(sp)                        # backchain = 0

        stw     r0,8(sp)                        # return pc = 0

        stwu    sp,-CYGARC_PPC_STACK_FRAME_SIZE(sp) # create new stack frame

                                                # where C code can save LR

        lwi     r5,restore_state                # get return link

        mtlr    r5                              # to link register

        .extern cyg_hal_exception_handler

        b       cyg_hal_exception_handler       # call C code, r3 = registers

        # When the call returns it will go to restore_state below.

##--------------------------------------------------------------------------

## The following macros are defined depending on whether the Interrupt

## system is using isr tables or chaining, and depending on the interrupt

## controller in the system.

#ifndef CYGPKG_HAL_POWERPC_INTC_DEFINED

## This is the simple version. No interrupt controller, CYGARC_PPCREG_VECTOR

## is updated with the decoded interrupt vector. Isr tables/chaining

## use same interrupt decoder.

## Bit 21 biffers between decrementer (0) and external (1).

        # decode the interrupt

        .macro  hal_intc_decode dreg,state

        lwz     \dreg,CYGARC_PPCREG_VECTOR(\state) # retrieve vector number,

        rlwinm  \dreg,\dreg,22,31,31               # isolate bit 21 and update

        stw     \dreg,CYGARC_PPCREG_VECTOR(\state) # vector in state frame.

        slwi    \dreg,\dreg,2                      # convert to word offset.

        .endm

#endif // CYGPKG_HAL_POWERPC_INTC_DEFINED

#---------------------------------------------------------------------------

# Common interrupt handling code.

        .globl cyg_hal_default_interrupt_vsr

cyg_hal_default_interrupt_vsr:

        # We come here with all register containing their

        # pre-exception values except:

        # R3    = ls 16 bits of vector address

        # R4    = saved CR

        # R5    = saved LR

        # LR    = VSR address

        # SPRG1 = old R3

        # SPRG2 = old R4

        # SPRG3 = old R5

        # SRR0  = old PC

        # SRR1  = old MSR

        subi    sp,sp,CYGARC_PPC_EXCEPTION_DECREMENT

                                        # leave space for registers and

                                        # a safety margin

#ifdef CYGPKG_HAL_POWERPC_PPC40x

// The caches on this processor are always enabled when the MMU is on

// (and disabled when off).  Thus we need to be careful about cache

// polution and staleness when changing the MMU state.

// At this point, the MMU is off due to the exception.  We need to

// flush the part of the cache which may be touched before the MMU

// is reenabled so that memory will be consistent when that happens.

// Of course, this is complicated by the fact that there are no "free"

// registers at this point in the code.

        dcbf    0,sp                    // Flushes first line

        stw     r3,0(sp)                // This is now safe

        li      r3,CYGARC_PPCREG_VECTOR // Flush lines which will be changed

        dcbf    r3,sp

        li      r3,CYGARC_PPCREG_CR

        dcbf    r3,sp

        li      r3,CYGARC_PPCREG_LR

        dcbf    r3,sp

        lwz     r3,0(sp)                // Restore register

#endif

        stw     r3,CYGARC_PPCREG_VECTOR(sp)    # stash vector

        stw     r4,CYGARC_PPCREG_CR(sp)        # stash CR

        stw     r5,CYGARC_PPCREG_LR(sp)        # stash LR

#ifdef CYGDBG_HAL_POWERPC_FRAME_WALLS

        # Mark this fram as an 1nterrupt frame

        lwi     r3,0xDDDDDD10

        stw     r3,CYGARC_PPCREG_WALL_HEAD(sp)

        lwi     r3,0xDDDDDD11

        stw     r3,CYGARC_PPCREG_WALL_TAIL(sp)

#endif

        # Enable MMU.

        lwi     r3,CYG_MSR

        sync

        mtmsr   r3

        sync

        mfspr   r3,SPRG1                # save original R3

        stw     r3,CYGARC_PPCREG_REGS+3*4(sp)

        mfspr   r4,SPRG2                # save original R4

        stw     r4,CYGARC_PPCREG_REGS+4*4(sp)

        mfspr   r5,SPRG3                # save original R5

        stw     r5,CYGARC_PPCREG_REGS+5*4(sp)

        stw     r0,CYGARC_PPCREG_REGS+0*4(sp)  # save R0

        stw     r2,CYGARC_PPCREG_REGS+2*4(sp)  # save R2

        mr      r3,sp                   # recreate original SP

        addi    r3,r3,CYGARC_PPC_EXCEPTION_DECREMENT

        stw     r3,CYGARC_PPCREG_REGS+1*4(sp)  # and save it in state

        # Save registers r6..r12/r31

        .set    _reg,6

        .rept   MAX_SAVE_REG+1-6

        stw     _reg,(CYGARC_PPCREG_REGS+_reg*4)(sp)

        .set    _reg,_reg+1

        .endr

        # Save registers used in vsr (r14+r15)

        stw     r14,CYGARC_PPCREG_REGS+14*4(sp)

        stw     r15,CYGARC_PPCREG_REGS+15*4(sp)

        # get remaining family CPU registers

        mfxer   r3

        mfctr   r4

        mfsrr0  r5

        mfsrr1  r6

        # and store them

        stw     r3,CYGARC_PPCREG_XER(sp)

        stw     r4,CYGARC_PPCREG_CTR(sp)

        stw     r5,CYGARC_PPCREG_PC(sp)

        stw     r6,CYGARC_PPCREG_MSR(sp)

        # Save variant registers

        hal_variant_save sp

        # Save FPU registers

        hal_fpu_save sp

        # The entire CPU state is now stashed on the stack,

        # increment the scheduler lock and call the ISR

        # for this vector.

#ifdef CYGFUN_HAL_COMMON_KERNEL_SUPPORT

        .extern cyg_scheduler_sched_lock

        lwi     r3,cyg_scheduler_sched_lock

        lwz     r4,0(r3)

        addi    r4,r4,1

        stw     r4,0(r3)

#endif

        mr      r14,sp                          # r14 = register dump

#ifdef CYGIMP_HAL_COMMON_INTERRUPTS_USE_INTERRUPT_STACK

        lwi     r3,__interrupt_stack            # stack top

        lwi     r4,__interrupt_stack_base       # stack base

        sub.    r5,sp,r4                        # sp - base

        blt     1f                              # if < 0 - not on istack

        sub.    r5,r3,sp                        # top - sp

        bgt     2f                              # if > 0 - already on istack

1:      mr      sp,r3                           # switch to istack

2:      stwu    r14,-4(sp)                      # save old SP on stack

#endif

        subi    sp,sp,CYGARC_PPC_STACK_FRAME_SIZE # make a null frame

        li      r0,0                            # R0 = 0

        stw     r0,0(sp)                        # backchain = 0

        stw     r0,8(sp)                        # return pc = 0

        stwu    sp,-CYGARC_PPC_STACK_FRAME_SIZE(sp) # create new stack frame

                                                # where C code can save LR

#if defined(CYGPKG_KERNEL_INSTRUMENT) && defined(CYGDBG_KERNEL_INSTRUMENT_INTR)

        lwi     r3,0x0301                       # r3 = type = INTR,RAISE

        lwz     r4,CYGARC_PPCREG_VECTOR(r14)    # arg1 = vector address

        srwi    r4,r4,8                         # arg1 = vector number

        xor     r5,r5,r5                        # arg2 = 0

        bl      cyg_instrument                  # call instrument function

#endif

        hal_intc_decode r15,r14                # get table index

#if defined(CYGDBG_HAL_DEBUG_GDB_CTRLC_SUPPORT) \

    || defined(CYGDBG_HAL_DEBUG_GDB_BREAK_SUPPORT)

        # If we are supporting Ctrl-C interrupts from GDB, we must squirrel

        # away a pointer to the save interrupt state here so that we can

        # plant a breakpoint at some later time.

        .extern hal_saved_interrupt_state

        lwi     r3,hal_saved_interrupt_state

        stw     r14,0(r3)

#endif

#ifdef CYGSEM_HAL_COMMON_INTERRUPTS_ALLOW_NESTING

#ifdef CYGPKG_HAL_POWERPC_MPC8xx

        # The CPM controller allows nested interrupts. However,

        # it sits on the back of the SIU controller which has no

        # HW support for this. In effect, SW masking of lower

        # priority IRQs in the SIU would be required for this to work.

#endif

#endif

        lwz     r3,CYGARC_PPCREG_VECTOR(r14)    # retrieve decoded vector #

        lwi     r6,hal_interrupt_handlers       # get interrupt handler table

        lwzx    r6,r6,r15                       # load routine pointer

        lwi     r4,hal_interrupt_data           # get interrupt data table

        lwzx    r4,r4,r15                       # load data pointer

                                                # R4 = data argument

        mr      r5,r14                          # R5 = saved registers

        mtctr   r6                              # put isr address in ctr

        bctrl                                   # branch to ctr reg and link

#ifdef CYGIMP_HAL_COMMON_INTERRUPTS_USE_INTERRUPT_STACK

        # If we are returning from the last nested interrupt, move back

        # to the thread stack. interrupt_end() must be called on the

        # thread stack since it potentially causes a context switch.

        # 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.

        lwz     sp,CYGARC_PPC_STACK_FRAME_SIZE*2(sp) # sp = *sp

        subi    sp,sp,CYGARC_PPC_STACK_FRAME_SIZE # make a null frame

        li      r0,0                            # R0 = 0

        stw     r0,0(sp)                        # backchain = 0

        stw     r0,8(sp)                        # return pc = 0

        stwu    sp,-CYGARC_PPC_STACK_FRAME_SIZE(sp) # create new stack frame

                                                # where C code can save LR

#endif

#ifdef CYGFUN_HAL_COMMON_KERNEL_SUPPORT

        # We only need to call _interrupt_end() when there is a kernel

        # present to do any tidying up.

        # on return r3 bit 1 will indicate whether a DSR is

        # to be posted. Pass this together with a pointer to

        # the interrupt object we have just used to the

        # interrupt tidy up routine.

        # Note that r14 and r15 are defined to be preserved across

        # calls by the calling convention, so they still contain

        # the register dump and the vector number respectively.

        lwi     r4,hal_interrupt_objects        # get interrupt object table

        lwzx    r4,r4,r15                       # load object pointer

        mr      r5,r14                          # arg3 = saved register dump

        .extern interrupt_end

        bl      interrupt_end                   # call into C to finish off

#endif

restore_state:

        # All done, restore CPU state and continue

        # retrieve CPU state pointer

        addi    sp,sp,CYGARC_PPC_STACK_FRAME_SIZE*2

        # Restore FPU registers

        hal_fpu_load sp

        # Restore variant registers

        hal_variant_load sp

        # get sprs we want to restore

        # stuff some of them into the CPU

        lwz     r3,CYGARC_PPCREG_XER(sp)

        lwz     r4,CYGARC_PPCREG_LR(sp)

        lwz     r5,CYGARC_PPCREG_CTR(sp)

        mtxer   r3

        mtlr    r4

        mtctr   r5

        # Restore registers used in vsr (r14+r15)

        lwz     r14,CYGARC_PPCREG_REGS+14*4(r1)

        lwz     r15,CYGARC_PPCREG_REGS+15*4(r1)

        # restore registers r6..r12/r31

        .set    _reg,6

        .rept   MAX_SAVE_REG+1-6

        lwz     _reg,(CYGARC_PPCREG_REGS+_reg*4)(sp)

        .set    _reg,_reg+1

        .endr

        hal_cpu_int_disable

        # restore R0 and R2

        lwz     r0,CYGARC_PPCREG_REGS+0*4(sp)

        lwz     r2,CYGARC_PPCREG_REGS+2*4(sp)

        # Here all the registers are loaded except

        # sp = HAL_SavedRegisters

        # r3 = ccr

        # r4 = srr0 = pc

        # r5 = srr1 = msr

        #

        # We have to disable interrupts while srr0 and

        # srr1 are loaded, since another interrupt will

        # destroy them.

        lwz     r3,CYGARC_PPCREG_CR(sp)

        lwz     r4,CYGARC_PPCREG_PC(sp)

        lwz     r5,CYGARC_PPCREG_MSR(sp)

        mtcr    r3                      # set ccr

        mtsrr0  r4                      # load old pc

        mtsrr1  r5                      # load old msr

#ifdef CYGDBG_HAL_POWERPC_FRAME_WALLS

        # Mark this frame as (almost) dead.

        lwi     r3,0xDDDDDDD0

        stw     r3,CYGARC_PPCREG_WALL_HEAD(sp)

        lwi     r3,0xDDDDDDD1

        stw     r3,CYGARC_PPCREG_WALL_TAIL(sp)

#endif

        lwz     r3,CYGARC_PPCREG_REGS+3*4(sp)  # load r3 value

        lwz     r4,CYGARC_PPCREG_REGS+4*4(sp)  # load r4 value

        lwz     r5,CYGARC_PPCREG_REGS+5*4(sp)  # load r5 value

        lwz     sp,CYGARC_PPCREG_REGS+1*4(sp)  # restore sp

        sync                            # settle things down

        isync

        rfi                             # and return

##-----------------------------------------------------------------------------

## Execute pending DSRs on the interrupt stack with interrupts enabled.

## Note: this can only be called from code running on a thread stack

#ifdef CYGIMP_HAL_COMMON_INTERRUPTS_USE_INTERRUPT_STACK

        .extern cyg_interrupt_call_pending_DSRs

FUNC_START(hal_interrupt_stack_call_pending_DSRs)

        # Change to interrupt stack, save state and set up stack for

        # calls to C code.

        mr      r3,sp

        lwi     r4,__interrupt_stack

        subi    r4,r4,24                        # make space on stack

        mr      sp,r4

        stw     r3,12(sp)                       # save old sp

        mfmsr   r3

        stw     r3,16(sp)                       # save old MSR

        mflr    r3

        stw     r3,20(sp)                       # save old LR

        li      r0,0

        stw     r0,0(sp)                        # clear back chain

        stw     r0,8(sp)                        # zero return pc

        hal_cpu_int_enable

        # Call into kernel which will execute DSRs

        stwu    sp,-CYGARC_PPC_STACK_FRAME_SIZE(sp)

        bl      cyg_interrupt_call_pending_DSRs

        addi    sp,sp,CYGARC_PPC_STACK_FRAME_SIZE

        lwz     r3,20(sp)                       # restore LR

        mtlr    r3

        lwz     r5,12(sp)                       # get SP from saved state

        lwz     r3,16(sp)                       # restore interrupt setting

        hal_cpu_int_merge r3

        mr      sp,r5                           # restore stack pointer

        blr                                     # and return to caller

#endif

#---------------------------------------------------------------------------

## Temporary interrupt stack

        .section ".bss"

        .balign 16

        .global cyg_interrupt_stack_base

cyg_interrupt_stack_base:

__interrupt_stack_base:

        .rept CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE

        .byte 0

        .endr

        .balign 16

        .global cyg_interrupt_stack

cyg_interrupt_stack:

__interrupt_stack:

        .long   0,0,0,0,0,0,0,0

#---------------------------------------------------------------------------

# end of vectors.S