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/*
* Carsten Langgaard, carstenl@mips.com
* Copyright (C) 1999, 2000 MIPS Technologies, Inc. All rights reserved.
*
* ########################################################################
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope 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 this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* ########################################################################
*
* Interrupt exception dispatch code.
*
*/
#include <linux/config.h>
#include <asm/asm.h>
#include <asm/mipsregs.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
#ifdef CONFIG_MIPS_ATLAS
#include <asm/mips-boards/atlasint.h>
#define CASCADE_IRQ MIPSCPU_INT_ATLAS
#define CASCADE_DISPATCH atlas_hw0_irqdispatch
#endif
#ifdef CONFIG_MIPS_MALTA
#include <asm/mips-boards/maltaint.h>
#define CASCADE_IRQ MIPSCPU_INT_I8259A
#define CASCADE_DISPATCH malta_hw0_irqdispatch
#endif
#ifdef CONFIG_MIPS_SEAD
#include <asm/mips-boards/seadint.h>
#endif
/* 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 MIPS board look basically (barring software
* IRQs which we don't use at all and all external interrupt sources are
* combined together on hardware interrupt 0 (MIPS IRQ 2)) like:
*
* MIPS IRQ Source
* -------- ------
* 0 Software (ignored)
* 1 Software (ignored)
* 2 Combined hardware interrupt (hw0)
* 3 Hardware (ignored)
* 4 Hardware (ignored)
* 5 Hardware (ignored)
* 6 Hardware (ignored)
* 7 R4k timer (what we use)
*
* Note: On the SEAD board thing are a little bit different.
* Here IRQ 2 (hw0) is wired to the UART0 and IRQ 3 (hw1) is wired
* wired to UART1.
*
* We handle the IRQ according to _our_ priority which is:
*
* Highest ---- R4k Timer
* Lowest ---- Combined hardware interrupt
*
* then we just return, if multiple IRQs are pending then we will just take
* another exception, big deal.
*/
.text
.set noreorder
.set noat
.align 5
NESTED(mipsIRQ, PT_SIZE, sp)
SAVE_ALL
CLI
.set at
mfc0 s0, CP0_CAUSE # get irq bits
mfc0 s1, CP0_STATUS # get irq mask
andi s0, ST0_IM # CAUSE.CE may be non-zero!
and s0, s1
#if defined(CONFIG_CPU_MIPS32) || defined(CONFIG_CPU_MIPS64)
.set mips32
clz a0, s0
.set mips0
negu a0
addu a0, 31-CAUSEB_IP
bltz a0, spurious
#else
beqz s0, spurious
li a0, 7
and t0, s0, 0xf000
sltiu t0, t0, 1
sll t0, 2
subu a0, t0
sll s0, t0
and t0, s0, 0xc000
sltiu t0, t0, 1
sll t0, 1
subu a0, t0
sll s0, t0
and t0, s0, 0x8000
sltiu t0, t0, 1
# sll t0, 0
subu a0, t0
# sll s0, t0
#endif
#ifdef CASCADE_IRQ
li a1, CASCADE_IRQ
bne a0, a1, 1f
addu a0, MIPSCPU_INT_BASE
jal CASCADE_DISPATCH
move a0, sp
j ret_from_irq
nop
1:
#else
addu a0, MIPSCPU_INT_BASE
#endif
jal do_IRQ
move a1, sp
j ret_from_irq
nop
spurious:
jal spurious_interrupt
nop
j ret_from_irq
nop
END(mipsIRQ)
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