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/*
* Carsten Langgaard, carstenl@mips.com
* Copyright (C) 2002 MIPS Technologies, Inc. All rights reserved.
* Copyright (C) 2003 Ralf Baechle (ralf@linux-mips.org)
* Copyright (C) 2004 Maciej W. Rozycki
*
* 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.
*
* Routines for generic manipulation of the interrupts found on the MIPS
* Sead board.
*/
#include <linux/init.h>
#include <linux/interrupt.h>
#include <asm/irq_cpu.h>
#include <asm/mipsregs.h>
#include <asm/system.h>
#include <asm/mips-boards/seadint.h>
static inline int clz(unsigned long x)
{
__asm__ (
" .set push \n"
" .set mips32 \n"
" clz %0, %1 \n"
" .set pop \n"
: "=r" (x)
: "r" (x));
return x;
}
/*
* Version of ffs that only looks at bits 12..15.
*/
static inline unsigned int irq_ffs(unsigned int pending)
{
#if defined(CONFIG_CPU_MIPS32) || defined(CONFIG_CPU_MIPS64)
return -clz(pending) + 31 - CAUSEB_IP;
#else
unsigned int a0 = 7;
unsigned int t0;
t0 = s0 & 0xf000;
t0 = t0 < 1;
t0 = t0 << 2;
a0 = a0 - t0;
s0 = s0 << t0;
t0 = s0 & 0xc000;
t0 = t0 < 1;
t0 = t0 << 1;
a0 = a0 - t0;
s0 = s0 << t0;
t0 = s0 & 0x8000;
t0 = t0 < 1;
//t0 = t0 << 2;
a0 = a0 - t0;
//s0 = s0 << t0;
return a0;
#endif
}
/*
* IRQs on the SEAD board look basically are combined together on hardware
* interrupt 0 (MIPS IRQ 2)) like:
*
* MIPS IRQ Source
* -------- ------
* 0 Software (ignored)
* 1 Software (ignored)
* 2 UART0 (hw0)
* 3 UART1 (hw1)
* 4 Hardware (ignored)
* 5 Hardware (ignored)
* 6 Hardware (ignored)
* 7 R4k timer (what we use)
*
* 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.
*/
asmlinkage void plat_irq_dispatch(void)
{
unsigned int pending = read_c0_cause() & read_c0_status() & ST0_IM;
int irq;
irq = irq_ffs(pending);
if (irq >= 0)
do_IRQ(MIPS_CPU_IRQ_BASE + irq);
else
spurious_interrupt();
}
void __init arch_init_irq(void)
{
mips_cpu_irq_init();
}
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