/*
* 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.
*
* ########################################################################
*
* Routines for generic manipulation of the interrupts found on the MIPS
* Atlas board.
*
*/
#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/mips-boards/atlas.h>
#include <asm/mips-boards/atlasint.h>
#include <asm/gdb-stub.h>
static struct atlas_ictrl_regs *atlas_hw0_icregs;
#if 0
#define DEBUG_INT(x...) printk(x)
#else
#define DEBUG_INT(x...)
#endif
void disable_atlas_irq(unsigned int irq_nr)
{
atlas_hw0_icregs->intrsten = (1 << (irq_nr-ATLASINT_BASE));
iob();
}
void enable_atlas_irq(unsigned int irq_nr)
{
atlas_hw0_icregs->intseten = (1 << (irq_nr-ATLASINT_BASE));
iob();
}
static unsigned int startup_atlas_irq(unsigned int irq)
{
enable_atlas_irq(irq);
return 0; /* never anything pending */
}
#define shutdown_atlas_irq disable_atlas_irq
#define mask_and_ack_atlas_irq disable_atlas_irq
static void end_atlas_irq(unsigned int irq)
{
if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
enable_atlas_irq(irq);
}
static struct hw_interrupt_type atlas_irq_type = {
.typename = "Atlas",
.startup = startup_atlas_irq,
.shutdown = shutdown_atlas_irq,
.enable = enable_atlas_irq,
.disable = disable_atlas_irq,
.ack = mask_and_ack_atlas_irq,
.end = end_atlas_irq,
};
static inline int ls1bit32(unsigned int x)
{
int b = 31, s;
s = 16; if (x << 16 == 0) s = 0; b -= s; x <<= s;
s = 8; if (x << 8 == 0) s = 0; b -= s; x <<= s;
s = 4; if (x << 4 == 0) s = 0; b -= s; x <<= s;
s = 2; if (x << 2 == 0) s = 0; b -= s; x <<= s;
s = 1; if (x << 1 == 0) s = 0; b -= s;
return b;
}
static inline void atlas_hw0_irqdispatch(struct pt_regs *regs)
{
unsigned long int_status;
int irq;
int_status = atlas_hw0_icregs->intstatus;
/* if int_status == 0, then the interrupt has already been cleared */
if (unlikely(int_status == 0))
return;
irq = ATLASINT_BASE + ls1bit32(int_status);
DEBUG_INT("atlas_hw0_irqdispatch: irq=%d\n", irq);
do_IRQ(irq, regs);
}
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 Atlas 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)
*
* 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(struct pt_regs *regs)
{
unsigned int pending = read_c0_cause() & read_c0_status() & ST0_IM;
int irq;
irq = irq_ffs(pending);
if (irq == MIPSCPU_INT_ATLAS)
atlas_hw0_irqdispatch(regs);
else if (irq > 0)
do_IRQ(MIPSCPU_INT_BASE + irq, regs);
else
spurious_interrupt(regs);
}
void __init arch_init_irq(void)
{
int i;
atlas_hw0_icregs = (struct atlas_ictrl_regs *)ioremap (ATLAS_ICTRL_REGS_BASE, sizeof(struct atlas_ictrl_regs *));
/*
* Mask out all interrupt by writing "1" to all bit position in
* the interrupt reset reg.
*/
atlas_hw0_icregs->intrsten = 0xffffffff;
for (i = ATLASINT_BASE; i <= ATLASINT_END; i++) {
irq_desc[i].status = IRQ_DISABLED;
irq_desc[i].action = 0;
irq_desc[i].depth = 1;
irq_desc[i].chip = &atlas_irq_type;
spin_lock_init(&irq_desc[i].lock);
}
}
