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int-handler.S
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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 1995, 1996, 1997 Paul M. Antoine and Harald Koerfgen
* Copyright (C) 2000, 2001, 2002, 2003, 2005 Maciej W. Rozycki
*
* Written by Ralf Baechle and Andreas Busse, modified for DECstation
* support by Paul Antoine and Harald Koerfgen.
*
* completely rewritten:
* Copyright (C) 1998 Harald Koerfgen
*
* Rewritten extensively for controller-driven IRQ support
* by Maciej W. Rozycki.
*/
#include <asm/addrspace.h>
#include <asm/asm.h>
#include <asm/mipsregs.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
#include <asm/dec/interrupts.h>
#include <asm/dec/ioasic_addrs.h>
#include <asm/dec/ioasic_ints.h>
#include <asm/dec/kn01.h>
#include <asm/dec/kn02.h>
#include <asm/dec/kn02xa.h>
#include <asm/dec/kn03.h>
#define KN02_CSR_BASE CKSEG1ADDR(KN02_SLOT_BASE + KN02_CSR)
#define KN02XA_IOASIC_BASE CKSEG1ADDR(KN02XA_SLOT_BASE + IOASIC_IOCTL)
#define KN03_IOASIC_BASE CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_IOCTL)
.text
.set noreorder
/*
* plat_irq_dispatch: 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 & Video
* 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(plat_irq_dispatch, PT_SIZE, ra)
.set noreorder
/*
* Get pending Interrupts
*/
mfc0 t0,CP0_CAUSE # get pending interrupts
mfc0 t1,CP0_STATUS
#ifdef CONFIG_32BIT
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_32BIT
and t2,t0
bnez t2,fpu # handle FPU immediately
#endif
/*
* Find irq with highest priority
*/
# open coded PTR_LA t1, cpu_mask_nr_tbl
#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
# open coded la t1, cpu_mask_nr_tbl
lui t1, %hi(cpu_mask_nr_tbl)
addiu t1, %lo(cpu_mask_nr_tbl)
#else
#error GCC `-msym32' option required for 64-bit DECstation builds
#endif
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_BASE>>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,IO_REG_SIR(t2) # get status: IOASIC sir
lw t1,IO_REG_SIMR(t2) # get mask: IOASIC simr
nop
1: and t0,t1 # mask out allowed ones
beqz t0,spurious
/*
* Find irq with highest priority
*/
# open coded PTR_LA t1,asic_mask_nr_tbl
#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
# open coded la t1, asic_mask_nr_tbl
lui t1, %hi(asic_mask_nr_tbl)
addiu t1, %lo(asic_mask_nr_tbl)
#else
#error GCC `-msym32' option required for 64-bit DECstation builds
#endif
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:
j dec_irq_dispatch
nop
#ifdef CONFIG_32BIT
fpu:
lw t0,fpu_kstat_irq
nop
lw t1,(t0)
nop
addu t1,1
j handle_fpe_int
sw t1,(t0)
#endif
spurious:
j spurious_interrupt
nop
END(plat_irq_dispatch)
/*
* 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");