/*
* This file contains the assembly code for the PowerPC
* IRQ veneers for RTEMS.
*
* The license and distribution terms for this file may be
* found in found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* Modified to support the MCP750.
* Modifications Copyright (C) 1999 Eric Valette. valette@crf.canon.fr
*
* Modifications to store nesting level in global _ISR_Nest_level
* variable instead of SPRG0. Andy Dachs <a.dachs@sstl.co.uk>
*
* Till Straumann <strauman@slac.stanford.edu>, 2005/4:
* - DONT enable FP across user ISR since fpregs are never saved!!
*
* $Id$
*/
#include <bsp/vectors.h>
#include <rtems/score/cpuopts.h> /* for PPC_HAS_FPU */
#include <rtems/score/cpu.h>
#include <libcpu/raw_exception.h>
#include <rtems/asm.h>
#define SYNC \
sync; \
isync
.text
.p2align 5
PUBLIC_VAR(decrementer_exception_vector_prolog_code)
SYM (decrementer_exception_vector_prolog_code):
/*
* let room for exception frame
*/
stwu r1, - (EXCEPTION_FRAME_END)(r1)
stw r4, GPR4_OFFSET(r1)
li r4, ASM_DEC_VECTOR
ba shared_raw_irq_code_entry
PUBLIC_VAR (decrementer_exception_vector_prolog_code_size)
decrementer_exception_vector_prolog_code_size = . - decrementer_exception_vector_prolog_code
PUBLIC_VAR(external_exception_vector_prolog_code)
SYM (external_exception_vector_prolog_code):
/*
* let room for exception frame
*/
stwu r1, - (EXCEPTION_FRAME_END)(r1)
stw r4, GPR4_OFFSET(r1)
li r4, ASM_EXT_VECTOR
ba shared_raw_irq_code_entry
PUBLIC_VAR (external_exception_vector_prolog_code_size)
external_exception_vector_prolog_code_size = . - external_exception_vector_prolog_code
PUBLIC_VAR(shared_raw_irq_code_entry)
PUBLIC_VAR(C_dispatch_irq_handler)
.p2align 5
SYM (shared_raw_irq_code_entry):
/*
* Entry conditions :
* Registers already saved : R1, R4
* R1 : points to a location with enough room for the
* interrupt frame
* R4 : vector number
*/
/*
* Save SRR0/SRR1 As soon As possible as it is the minimal needed
* to reenable exception processing
*/
stw r0, GPR0_OFFSET(r1)
stw r2, GPR2_OFFSET(r1)
stw r3, GPR3_OFFSET(r1)
mfsrr0 r0
mfsrr1 r2
mfmsr r3
stw r0, SRR0_FRAME_OFFSET(r1)
stw r2, SRR1_FRAME_OFFSET(r1)
/*
* Enable data and instruction address translation, exception recovery
*
* also, on CPUs with FP, enable FP so that FP context can be
* saved and restored (using FP instructions)
*/
ori r3, r3, MSR_RI /*| MSR_IR | MSR_DR*/
mtmsr r3
SYNC
/*
* Push C scratch registers on the current stack. It may
* actually be the thread stack or the interrupt stack.
* Anyway we have to make it in order to be able to call C/C++
* functions. Depending on the nesting interrupt level, we will
* switch to the right stack later.
*/
stw r5, GPR5_OFFSET(r1)
stw r6, GPR6_OFFSET(r1)
stw r7, GPR7_OFFSET(r1)
stw r8, GPR8_OFFSET(r1)
stw r9, GPR9_OFFSET(r1)
stw r10, GPR10_OFFSET(r1)
stw r11, GPR11_OFFSET(r1)
stw r12, GPR12_OFFSET(r1)
stw r13, GPR13_OFFSET(r1)
mfcr r5
mfctr r6
mfxer r7
mflr r8
stw r5, EXC_CR_OFFSET(r1)
stw r6, EXC_CTR_OFFSET(r1)
stw r7, EXC_XER_OFFSET(r1)
stw r8, EXC_LR_OFFSET(r1)
/*
* Add some non volatile registers to store information
* that will be used when returning from C handler
*/
stw r14, GPR14_OFFSET(r1)
stw r15, GPR15_OFFSET(r1)
/*
* save current stack pointer location in R14
*/
addi r14, r1, 0
/*
* store part of _Thread_Dispatch_disable_level address in R15
*/
addis r15,0, _Thread_Dispatch_disable_level@ha
/*
* Get current nesting level in R2
*/
/* mfspr r2, SPRG0 */
addis r6, 0, _ISR_Nest_level@ha
lwz r2, _ISR_Nest_level@l( r6 )
/*
* Check if stack switch is necessary
*/
cmpwi r2,0
bne nested
mfspr r1, SPRG1
nested:
/*
* Start Incrementing nesting level in R2
*/
addi r2,r2,1
addis r6, 0, _ISR_Nest_level@ha
stw r2, _ISR_Nest_level@l( r6 )
/*
* Start Incrementing _Thread_Dispatch_disable_level R4 = _Thread_Dispatch_disable_level
*/
lwz r6,_Thread_Dispatch_disable_level@l(r15)
/*
* store new nesting level in SPRG0
*/
/* mtspr SPRG0, r2 */
addi r6, r6, 1
mfmsr r5
/*
* store new _Thread_Dispatch_disable_level value
*/
stw r6, _Thread_Dispatch_disable_level@l(r15)
/*
* We are now running on the interrupt stack. External and decrementer
* exceptions are still disabled. I see no purpose trying to optimize
* further assembler code.
*/
/*
* Call C exception handler for decrementer Interrupt frame is passed just
* in case...
*/
addi r3, r14, 0x8
bl C_dispatch_irq_handler /* C_dispatch_irq_handler(cpu_interrupt_frame* r3, vector r4) */
/*
* start decrementing nesting level. Note : do not test result against 0
* value as an easy exit condition because if interrupt nesting level > 1
* then _Thread_Dispatch_disable_level > 1
*/
/* mfspr r2, SPRG0 */
addis r6, 0, _ISR_Nest_level@ha
lwz r2, _ISR_Nest_level@l( r6 )
/*
* start decrementing _Thread_Dispatch_disable_level
*/
lwz r3,_Thread_Dispatch_disable_level@l(r15)
addi r2, r2, -1 /* Continue decrementing nesting level */
addi r3, r3, -1 /* Continue decrementing _Thread_Dispatch_disable_level */
stw r2, _ISR_Nest_level@l( r6 )
/* mtspr SPRG0, r2 */ /* End decrementing nesting level */
stw r3,_Thread_Dispatch_disable_level@l(r15) /* End decrementing _Thread_Dispatch_disable_level */
cmpwi r3, 0
/*
* switch back to original stack (done here just optimize registers
* contention. Could have been done before...)
*/
addi r1, r14, 0
bne easy_exit /* if (_Thread_Dispatch_disable_level != 0) goto easy_exit */
/*
* Here we are running again on the thread system stack.
* We have interrupt nesting level = _Thread_Dispatch_disable_level = 0.
* Interrupt are still disabled. Time to check if scheduler request to
* do something with the current thread...
*/
addis r4, 0, _Context_Switch_necessary@ha
lwz r5, _Context_Switch_necessary@l(r4)
cmpwi r5, 0
bne switch
addis r6, 0, _ISR_Signals_to_thread_executing@ha
lwz r7, _ISR_Signals_to_thread_executing@l(r6)
cmpwi r7, 0
li r8, 0
beq easy_exit
stw r8, _ISR_Signals_to_thread_executing@l(r6)
/*
* going to call _ThreadProcessSignalsFromIrq
* Push a complete exception like frame...
*/
stmw r16, GPR16_OFFSET(r1)
addi r3, r1, 0x8
/*
* compute SP at exception entry
*/
addi r2, r1, EXCEPTION_FRAME_END
/*
* store it at the right place
*/
stw r2, GPR1_OFFSET(r1)
/*
* Call High Level signal handling code
*/
bl _ThreadProcessSignalsFromIrq
/*
* start restoring exception like frame
*/
lwz r31, EXC_CTR_OFFSET(r1)
lwz r30, EXC_XER_OFFSET(r1)
lwz r29, EXC_CR_OFFSET(r1)
lwz r28, EXC_LR_OFFSET(r1)
mtctr r31
mtxer r30
mtcr r29
mtlr r28
lmw r4, GPR4_OFFSET(r1)
lwz r2, GPR2_OFFSET(r1)
lwz r0, GPR0_OFFSET(r1)
/*
* Disable data and instruction translation. Make path non recoverable...
*/
mfmsr r3
xori r3, r3, MSR_RI /*| MSR_IR | MSR_DR*/
mtmsr r3
SYNC
/*
* Restore rfi related settings
*/
lwz r3, SRR1_FRAME_OFFSET(r1)
mtsrr1 r3
lwz r3, SRR0_FRAME_OFFSET(r1)
mtsrr0 r3
lwz r3, GPR3_OFFSET(r1)
addi r1,r1, EXCEPTION_FRAME_END
SYNC
rfi
switch:
#if ( PPC_HAS_FPU != 0 )
#if ! defined( CPU_USE_DEFERRED_FP_SWITCH )
#error missing include file???
#endif
mfmsr r4
#if ( CPU_USE_DEFERRED_FP_SWITCH == TRUE )
/* if the executing thread has FP enabled propagate
* this now so _Thread_Dispatch can save/restore the FPREGS
* NOTE: it is *crucial* to disable the FPU across the
* user ISR [independent of using the 'deferred'
* strategy or not]. We don't save FP regs across
* the user ISR and hence we prefer an exception to
* be raised rather than experiencing corruption.
*/
lwz r3, SRR1_FRAME_OFFSET(r1)
rlwimi r4, r3, 0, 18, 18 /* MSR_FP */
#else
ori r4, r4, MSR_FP
#endif
mtmsr r4
#endif
bl SYM (_Thread_Dispatch)
easy_exit:
/*
* start restoring interrupt frame
*/
lwz r3, EXC_CTR_OFFSET(r1)
lwz r4, EXC_XER_OFFSET(r1)
lwz r5, EXC_CR_OFFSET(r1)
lwz r6, EXC_LR_OFFSET(r1)
mtctr r3
mtxer r4
mtcr r5
mtlr r6
lwz r15, GPR15_OFFSET(r1)
lwz r14, GPR14_OFFSET(r1)
lwz r13, GPR13_OFFSET(r1)
lwz r12, GPR12_OFFSET(r1)
lwz r11, GPR11_OFFSET(r1)
lwz r10, GPR10_OFFSET(r1)
lwz r9, GPR9_OFFSET(r1)
lwz r8, GPR8_OFFSET(r1)
lwz r7, GPR7_OFFSET(r1)
lwz r6, GPR6_OFFSET(r1)
lwz r5, GPR5_OFFSET(r1)
/*
* Disable nested exception processing, data and instruction
* translation.
*/
mfmsr r3
xori r3, r3, MSR_RI /*| MSR_IR | MSR_DR*/
mtmsr r3
SYNC
/*
* Restore rfi related settings
*/
lwz r4, SRR1_FRAME_OFFSET(r1)
lwz r2, SRR0_FRAME_OFFSET(r1)
lwz r3, GPR3_OFFSET(r1)
lwz r0, GPR0_OFFSET(r1)
mtsrr1 r4
mtsrr0 r2
lwz r4, GPR4_OFFSET(r1)
lwz r2, GPR2_OFFSET(r1)
addi r1,r1, EXCEPTION_FRAME_END
SYNC
rfi
