/*
|
* include/asm-mips/i8259.h
|
*
|
* i8259A interrupt definitions.
|
*
|
* Copyright (C) 2003 Maciej W. Rozycki
|
* Copyright (C) 2003 Ralf Baechle <ralf@linux-mips.org>
|
*
|
* This program is free software; you can redistribute it and/or
|
* modify it under the terms of the GNU General Public License
|
* as published by the Free Software Foundation; either version
|
* 2 of the License, or (at your option) any later version.
|
*/
|
#ifndef _ASM_I8259_H
|
#define _ASM_I8259_H
|
|
#include <linux/compiler.h>
|
#include <linux/spinlock.h>
|
|
#include <asm/io.h>
|
#include <irq.h>
|
|
/* i8259A PIC registers */
|
#define PIC_MASTER_CMD 0x20
|
#define PIC_MASTER_IMR 0x21
|
#define PIC_MASTER_ISR PIC_MASTER_CMD
|
#define PIC_MASTER_POLL PIC_MASTER_ISR
|
#define PIC_MASTER_OCW3 PIC_MASTER_ISR
|
#define PIC_SLAVE_CMD 0xa0
|
#define PIC_SLAVE_IMR 0xa1
|
|
/* i8259A PIC related value */
|
#define PIC_CASCADE_IR 2
|
#define MASTER_ICW4_DEFAULT 0x01
|
#define SLAVE_ICW4_DEFAULT 0x01
|
#define PIC_ICW4_AEOI 2
|
|
extern raw_spinlock_t i8259A_lock;
|
|
extern void make_8259A_irq(unsigned int irq);
|
|
extern void init_i8259_irqs(void);
|
|
/**
|
* i8159_set_poll() - Override the i8259 polling function
|
* @poll: pointer to platform-specific polling function
|
*
|
* Call this to override the generic i8259 polling function, which directly
|
* accesses i8259 registers, with a platform specific one which may be faster
|
* in cases where hardware provides a more optimal means of polling for an
|
* interrupt.
|
*/
|
extern void i8259_set_poll(int (*poll)(void));
|
|
/*
|
* Do the traditional i8259 interrupt polling thing. This is for the few
|
* cases where no better interrupt acknowledge method is available and we
|
* absolutely must touch the i8259.
|
*/
|
static inline int i8259_irq(void)
|
{
|
int irq;
|
|
raw_spin_lock(&i8259A_lock);
|
|
/* Perform an interrupt acknowledge cycle on controller 1. */
|
outb(0x0C, PIC_MASTER_CMD); /* prepare for poll */
|
irq = inb(PIC_MASTER_CMD) & 7;
|
if (irq == PIC_CASCADE_IR) {
|
/*
|
* Interrupt is cascaded so perform interrupt
|
* acknowledge on controller 2.
|
*/
|
outb(0x0C, PIC_SLAVE_CMD); /* prepare for poll */
|
irq = (inb(PIC_SLAVE_CMD) & 7) + 8;
|
}
|
|
if (unlikely(irq == 7)) {
|
/*
|
* This may be a spurious interrupt.
|
*
|
* Read the interrupt status register (ISR). If the most
|
* significant bit is not set then there is no valid
|
* interrupt.
|
*/
|
outb(0x0B, PIC_MASTER_ISR); /* ISR register */
|
if(~inb(PIC_MASTER_ISR) & 0x80)
|
irq = -1;
|
}
|
|
raw_spin_unlock(&i8259A_lock);
|
|
return likely(irq >= 0) ? irq + I8259A_IRQ_BASE : irq;
|
}
|
|
#endif /* _ASM_I8259_H */
|
