/* * irq_asm.S * * 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. * * * MPC5xx port sponsored by Defence Research and Development Canada - Suffield * Copyright (C) 2004, Real-Time Systems Inc. (querbach@realtime.bc.ca) * * Derived from libbsp/powerpc/mbx8xx/irq/irq_asm.S: * * Modified to support the MCP750. * Modifications Copyright (C) 1999 Eric Valette. valette@crf.canon.fr * * Till Straumann , 2003/7: * - store isr nesting level in _ISR_Nest_level rather than * SPRG0 - RTEMS relies on that variable. * * $Id$ */ #include #include #include #include #define SYNC \ sync; \ isync /* * Common handler for interrupt exceptions. * * The function CPU_rtems_irq_mng_init() initializes the decrementer and * external interrupt entries in the exception handler table with pointers * to this routine, which saves the remainder of the interrupted code's * state, then calls C_dispatch_irq_handler(). * * On entry, R1 points to a new exception stack frame in which R3, R4, and * LR have been saved. R4 holds the exception number. */ PUBLIC_VAR(C_dispatch_irq_handler) PUBLIC_VAR(dispatch_irq_handler) SYM (dispatch_irq_handler): /* * Save SRR0/SRR1 As soon As possible as it is the minimal needed * to re-enable exception processing. * * Note that R2 should never change (it's the EABI pointer to * .sdata2), but we save it just in case. */ stw r0, GPR0_OFFSET(r1) stw r2, GPR2_OFFSET(r1) mfsrr0 r0 mfsrr1 r3 stw r0, SRR0_FRAME_OFFSET(r1) stw r3, SRR1_FRAME_OFFSET(r1) /* * Enable exception recovery. Also enable FP so that FP context * can be saved and restored (using FP instructions). */ mfmsr r3 ori r3, r3, MSR_RI | MSR_FP 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 stw r5, EXC_CR_OFFSET(r1) stw r6, EXC_CTR_OFFSET(r1) stw r7, EXC_XER_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 /* * Retrieve current nesting level from _ISR_Nest_level */ lis r7, _ISR_Nest_level@ha lwz r3, _ISR_Nest_level@l(r7) /* * Check if stack switch is necessary */ cmpwi r3, 0 bne nested mfspr r1, SPRG1 /* switch to interrupt stack */ nested: /* * Start Incrementing nesting level in R3 */ addi r3, r3, 1 /* * Start Incrementing _Thread_Dispatch_disable_level R4 = _Thread_Dispatch_disable_level */ lwz r6, _Thread_Dispatch_disable_level@l(r15) /* store new nesting level in _ISR_Nest_level */ stw r3, _ISR_Nest_level@l(r7) addi r6, r6, 1 /* * 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 or external interrupt. * Pass frame along just in case.. * * C_dispatch_irq_handler(cpu_interrupt_frame* r3, vector r4) */ addi r3, r14, 0x8 bl C_dispatch_irq_handler /* * 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 */ lis r7, _ISR_Nest_level@ha lwz r4, _ISR_Nest_level@l(r7) /* * start decrementing _Thread_Dispatch_disable_level */ lwz r3,_Thread_Dispatch_disable_level@l(r15) addi r4, r4, -1 /* Continue decrementing nesting level */ addi r3, r3, -1 /* Continue decrementing _Thread_Dispatch_disable_level */ stw r4, _ISR_Nest_level@l(r7) /* 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 r4, r1, EXCEPTION_FRAME_END /* * store it at the right place */ stw r4, 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) /* * Make path non recoverable... */ mtspr nri, r0 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: 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. */ mtspr nri, r0 SYNC /* * Restore rfi related settings */ lwz r4, SRR1_FRAME_OFFSET(r1) lwz r3, SRR0_FRAME_OFFSET(r1) lwz r2, GPR2_OFFSET(r1) lwz r0, GPR0_OFFSET(r1) mtsrr1 r4 mtsrr0 r3 lwz r4, GPR4_OFFSET(r1) lwz r3, GPR3_OFFSET(r1) addi r1,r1, EXCEPTION_FRAME_END SYNC rfi