/* * arch/mips/dec/int-handler.S * * Copyright (C) 1995, 1996, 1997 Paul M. Antoine and Harald Koerfgen * Copyright (C) 2000, 2001, 2002 Maciej W. Rozycki * * Written by Ralf Baechle and Andreas Busse, modified for DECStation * support by Paul Antoine and Harald Koerfgen. * * completly rewritten: * Copyright (C) 1998 Harald Koerfgen * * Rewritten extensively for controller-driven IRQ support * by Maciej W. Rozycki. */ #include #include #include #include #include #include #include #include #include #include #include #include .text .set noreorder /* * decstation_handle_int: Interrupt handler for DECStations * * We follow the model in the Indy interrupt code by David Miller, where he * says: a lot of complication here is taken away because: * * 1) We handle one interrupt and return, sitting in a loop * and moving across all the pending IRQ bits in the cause * register is _NOT_ the answer, the common case is one * pending IRQ so optimize in that direction. * * 2) We need not check against bits in the status register * IRQ mask, that would make this routine slow as hell. * * 3) Linux only thinks in terms of all IRQs on or all IRQs * off, nothing in between like BSD spl() brain-damage. * * Furthermore, the IRQs on the DECStations look basically (barring * software IRQs which we don't use at all) like... * * DS2100/3100's, aka kn01, aka Pmax: * * MIPS IRQ Source * -------- ------ * 0 Software (ignored) * 1 Software (ignored) * 2 SCSI * 3 Lance Ethernet * 4 DZ11 serial * 5 RTC * 6 Memory Controller * 7 FPU * * DS5000/200, aka kn02, aka 3max: * * MIPS IRQ Source * -------- ------ * 0 Software (ignored) * 1 Software (ignored) * 2 TurboChannel * 3 RTC * 4 Reserved * 5 Memory Controller * 6 Reserved * 7 FPU * * DS5000/1xx's, aka kn02ba, aka 3min: * * MIPS IRQ Source * -------- ------ * 0 Software (ignored) * 1 Software (ignored) * 2 TurboChannel Slot 0 * 3 TurboChannel Slot 1 * 4 TurboChannel Slot 2 * 5 TurboChannel Slot 3 (ASIC) * 6 Halt button * 7 FPU/R4k timer * * DS5000/2x's, aka kn02ca, aka maxine: * * MIPS IRQ Source * -------- ------ * 0 Software (ignored) * 1 Software (ignored) * 2 Periodic Interrupt (100usec) * 3 RTC * 4 I/O write timeout * 5 TurboChannel (ASIC) * 6 Halt Keycode from Access.Bus keyboard (CTRL-ALT-ENTER) * 7 FPU/R4k timer * * DS5000/2xx's, aka kn03, aka 3maxplus: * * MIPS IRQ Source * -------- ------ * 0 Software (ignored) * 1 Software (ignored) * 2 System Board (ASIC) * 3 RTC * 4 Reserved * 5 Memory * 6 Halt Button * 7 FPU/R4k timer * * We handle the IRQ according to _our_ priority (see setup.c), * then we just return. If multiple IRQs are pending then we will * just take another exception, big deal. */ .align 5 NESTED(decstation_handle_int, PT_SIZE, ra) .set noat SAVE_ALL CLI # TEST: interrupts should be off .set at .set noreorder /* * Get pending Interrupts */ mfc0 t0,CP0_CAUSE # get pending interrupts mfc0 t1,CP0_STATUS #ifdef CONFIG_MIPS32 lw t2,cpu_fpu_mask #endif andi t0,ST0_IM # CAUSE.CE may be non-zero! and t0,t1 # isolate allowed ones beqz t0,spurious #ifdef CONFIG_MIPS32 and t2,t0 bnez t2,fpu # handle FPU immediately #endif /* * Find irq with highest priority */ PTR_LA t1,cpu_mask_nr_tbl 1: lw t2,(t1) nop and t2,t0 beqz t2,1b addu t1,2*PTRSIZE # delay slot /* * Do the low-level stuff */ lw a0,(-PTRSIZE)(t1) nop bgez a0,handle_it # irq_nr >= 0? # irq_nr < 0: it is an address nop jr a0 # a trick to save a branch: lui t2,(KN03_IOASIC_BASE>>16)&0xffff # upper part of IOASIC Address /* * Handle "IRQ Controller" Interrupts * Masked Interrupts are still visible and have to be masked "by hand". */ FEXPORT(kn02_io_int) # 3max lui t0,(KN02_CSR_ADDR>>16)&0xffff # get interrupt status and mask lw t0,(t0) nop andi t1,t0,KN02_IRQ_ALL b 1f srl t0,16 # shift interrupt mask FEXPORT(kn02xa_io_int) # 3min/maxine lui t2,(KN02XA_IOASIC_BASE>>16)&0xffff # upper part of IOASIC Address FEXPORT(kn03_io_int) # 3max+ (t2 loaded earlier) lw t0,SIR(t2) # get status: IOASIC isr lw t1,SIMR(t2) # get mask: IOASIC isrm nop 1: and t0,t1 # mask out allowed ones beqz t0,spurious /* * Find irq with highest priority */ PTR_LA t1,asic_mask_nr_tbl 2: lw t2,(t1) nop and t2,t0 beq zero,t2,2b addu t1,2*PTRSIZE # delay slot /* * Do the low-level stuff */ lw a0,%lo(-PTRSIZE)(t1) nop bgez a0,handle_it # irq_nr >= 0? # irq_nr < 0: it is an address nop jr a0 nop # delay slot /* * Dispatch low-priority interrupts. We reconsider all status * bits again, which looks like a lose, but it makes the code * simple and O(log n), so it gets compensated. */ FEXPORT(cpu_all_int) # HALT, timers, software junk li a0,DEC_CPU_IRQ_BASE srl t0,CAUSEB_IP li t1,CAUSEF_IP>>CAUSEB_IP # mask b 1f li t2,4 # nr of bits / 2 FEXPORT(kn02_all_int) # impossible ? li a0,KN02_IRQ_BASE li t1,KN02_IRQ_ALL # mask b 1f li t2,4 # nr of bits / 2 FEXPORT(asic_all_int) # various I/O ASIC junk li a0,IO_IRQ_BASE li t1,IO_IRQ_ALL # mask b 1f li t2,8 # nr of bits / 2 /* * Dispatch DMA interrupts -- O(log n). */ FEXPORT(asic_dma_int) # I/O ASIC DMA events li a0,IO_IRQ_BASE+IO_INR_DMA srl t0,IO_INR_DMA li t1,IO_IRQ_DMA>>IO_INR_DMA # mask li t2,8 # nr of bits / 2 /* * Find irq with highest priority. * Highest irq number takes precedence. */ 1: srlv t3,t1,t2 2: xor t1,t3 and t3,t0,t1 beqz t3,3f nop move t0,t3 addu a0,t2 3: srl t2,1 bnez t2,2b srlv t3,t1,t2 handle_it: jal do_IRQ move a1,sp j ret_from_irq nop #ifdef CONFIG_MIPS32 fpu: j handle_fpe_int nop #endif spurious: j spurious_interrupt nop END(decstation_handle_int) /* * Generic unimplemented interrupt routines -- cpu_mask_nr_tbl * and asic_mask_nr_tbl are initialized to point all interrupts here. * The tables are then filled in by machine-specific initialisation * in dec_setup(). */ FEXPORT(dec_intr_unimplemented) move a1,t0 # cheats way of printing an arg! PANIC("Unimplemented cpu interrupt! CP0_CAUSE: 0x%08x"); FEXPORT(asic_intr_unimplemented) move a1,t0 # cheats way of printing an arg! PANIC("Unimplemented asic interrupt! ASIC ISR: 0x%08x");