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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Code to handle x86 style IRQs plus some generic interrupt stuff.
*
* Copyright (C) 1992 Linus Torvalds
* Copyright (C) 1994 - 2000 Ralf Baechle
*/
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <asm/io.h>
void enable_8259A_irq(unsigned int irq);
void disable_8259A_irq(unsigned int irq);
/*
* This is the 'legacy' 8259A Programmable Interrupt Controller,
* present in the majority of PC/AT boxes.
* plus some generic x86 specific things if generic specifics makes
* any sense at all.
* this file should become arch/i386/kernel/irq.c when the old irq.c
* moves to arch independent land
*/
spinlock_t i8259A_lock = SPIN_LOCK_UNLOCKED;
static void end_8259A_irq (unsigned int irq)
{
if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
enable_8259A_irq(irq);
}
#define shutdown_8259A_irq disable_8259A_irq
void mask_and_ack_8259A(unsigned int);
static unsigned int startup_8259A_irq(unsigned int irq)
{
enable_8259A_irq(irq);
return 0; /* never anything pending */
}
static struct hw_interrupt_type i8259A_irq_type = {
"XT-PIC",
startup_8259A_irq,
shutdown_8259A_irq,
enable_8259A_irq,
disable_8259A_irq,
mask_and_ack_8259A,
end_8259A_irq,
NULL
};
/*
* 8259A PIC functions to handle ISA devices:
*/
/*
* This contains the irq mask for both 8259A irq controllers,
*/
static unsigned int cached_irq_mask = 0xffff;
#define __byte(x,y) (((unsigned char *)&(y))[x])
#define cached_21 (__byte(0,cached_irq_mask))
#define cached_A1 (__byte(1,cached_irq_mask))
void disable_8259A_irq(unsigned int irq)
{
unsigned int mask = 1 << irq;
unsigned long flags;
spin_lock_irqsave(&i8259A_lock, flags);
cached_irq_mask |= mask;
if (irq & 8)
outb(cached_A1,0xA1);
else
outb(cached_21,0x21);
spin_unlock_irqrestore(&i8259A_lock, flags);
}
void enable_8259A_irq(unsigned int irq)
{
unsigned int mask = ~(1 << irq);
unsigned long flags;
spin_lock_irqsave(&i8259A_lock, flags);
cached_irq_mask &= mask;
if (irq & 8)
outb(cached_A1,0xA1);
else
outb(cached_21,0x21);
spin_unlock_irqrestore(&i8259A_lock, flags);
}
int i8259A_irq_pending(unsigned int irq)
{
unsigned int mask = 1 << irq;
unsigned long flags;
int ret;
spin_lock_irqsave(&i8259A_lock, flags);
if (irq < 8)
ret = inb(0x20) & mask;
else
ret = inb(0xA0) & (mask >> 8);
spin_unlock_irqrestore(&i8259A_lock, flags);
return ret;
}
void make_8259A_irq(unsigned int irq)
{
disable_irq_nosync(irq);
irq_desc[irq].handler = &i8259A_irq_type;
enable_irq(irq);
}
/*
* This function assumes to be called rarely. Switching between
* 8259A registers is slow.
* This has to be protected by the irq controller spinlock
* before being called.
*/
static inline int i8259A_irq_real(unsigned int irq)
{
int value;
int irqmask = 1 << irq;
if (irq < 8) {
outb(0x0B,0x20); /* ISR register */
value = inb(0x20) & irqmask;
outb(0x0A,0x20); /* back to the IRR register */
return value;
}
outb(0x0B,0xA0); /* ISR register */
value = inb(0xA0) & (irqmask >> 8);
outb(0x0A,0xA0); /* back to the IRR register */
return value;
}
/*
* Careful! The 8259A is a fragile beast, it pretty
* much _has_ to be done exactly like this (mask it
* first, _then_ send the EOI, and the order of EOI
* to the two 8259s is important!
*/
void mask_and_ack_8259A(unsigned int irq)
{
unsigned int irqmask = 1 << irq;
unsigned long flags;
spin_lock_irqsave(&i8259A_lock, flags);
/*
* Lightweight spurious IRQ detection. We do not want to overdo
* spurious IRQ handling - it's usually a sign of hardware problems, so
* we only do the checks we can do without slowing down good hardware
* nnecesserily.
*
* Note that IRQ7 and IRQ15 (the two spurious IRQs usually resulting
* rom the 8259A-1|2 PICs) occur even if the IRQ is masked in the 8259A.
* Thus we can check spurious 8259A IRQs without doing the quite slow
* i8259A_irq_real() call for every IRQ. This does not cover 100% of
* spurious interrupts, but should be enough to warn the user that
* there is something bad going on ...
*/
if (cached_irq_mask & irqmask)
goto spurious_8259A_irq;
cached_irq_mask |= irqmask;
handle_real_irq:
if (irq & 8) {
inb(0xA1); /* DUMMY - (do we need this?) */
outb(cached_A1,0xA1);
outb(0x60+(irq&7),0xA0);/* 'Specific EOI' to slave */
outb(0x62,0x20); /* 'Specific EOI' to master-IRQ2 */
} else {
inb(0x21); /* DUMMY - (do we need this?) */
outb(cached_21,0x21);
outb(0x60+irq,0x20); /* 'Specific EOI' to master */
}
spin_unlock_irqrestore(&i8259A_lock, flags);
return;
spurious_8259A_irq:
/*
* this is the slow path - should happen rarely.
*/
if (i8259A_irq_real(irq))
/*
* oops, the IRQ _is_ in service according to the
* 8259A - not spurious, go handle it.
*/
goto handle_real_irq;
{
static int spurious_irq_mask = 0;
/*
* At this point we can be sure the IRQ is spurious,
* lets ACK and report it. [once per IRQ]
*/
if (!(spurious_irq_mask & irqmask)) {
printk("spurious 8259A interrupt: IRQ%d.\n", irq);
spurious_irq_mask |= irqmask;
}
irq_err_count++;
/*
* Theoretically we do not have to handle this IRQ,
* but in Linux this does not cause problems and is
* simpler for us.
*/
goto handle_real_irq;
}
}
void __init init_8259A(int auto_eoi)
{
unsigned long flags;
spin_lock_irqsave(&i8259A_lock, flags);
outb(0xff, 0x21); /* mask all of 8259A-1 */
outb(0xff, 0xA1); /* mask all of 8259A-2 */
/*
* outb_p - this has to work on a wide range of PC hardware.
*/
outb_p(0x11, 0x20); /* ICW1: select 8259A-1 init */
outb_p(0x20 + 0, 0x21); /* ICW2: 8259A-1 IR0-7 mapped to 0x20-0x27 */
outb_p(0x04, 0x21); /* 8259A-1 (the master) has a slave on IR2 */
if (auto_eoi)
outb_p(0x03, 0x21); /* master does Auto EOI */
else
outb_p(0x01, 0x21); /* master expects normal EOI */
outb_p(0x11, 0xA0); /* ICW1: select 8259A-2 init */
outb_p(0x20 + 8, 0xA1); /* ICW2: 8259A-2 IR0-7 mapped to 0x28-0x2f */
outb_p(0x02, 0xA1); /* 8259A-2 is a slave on master's IR2 */
outb_p(0x01, 0xA1); /* (slave's support for AEOI in flat mode
is to be investigated) */
if (auto_eoi)
/*
* in AEOI mode we just have to mask the interrupt
* when acking.
*/
i8259A_irq_type.ack = disable_8259A_irq;
else
i8259A_irq_type.ack = mask_and_ack_8259A;
udelay(100); /* wait for 8259A to initialize */
outb(cached_21, 0x21); /* restore master IRQ mask */
outb(cached_A1, 0xA1); /* restore slave IRQ mask */
spin_unlock_irqrestore(&i8259A_lock, flags);
}
asmlinkage void i8259_do_irq(int irq, struct pt_regs regs)
{
panic("i8259_do_irq: I want to be implemented");
}
/*
* IRQ2 is cascade interrupt to second interrupt controller
*/
static struct irqaction irq2 = {
no_action, 0, 0, "cascade", NULL, NULL
};
static struct resource pic1_io_resource = {
"pic1", 0x20, 0x3f, IORESOURCE_BUSY
};
static struct resource pic2_io_resource = {
"pic2", 0xa0, 0xbf, IORESOURCE_BUSY
};
/*
* On systems with i8259-style interrupt controllers we assume for
* driver compatibility reasons interrupts 0 - 15 to be the i8295
* interrupts even if the hardware uses a different interrupt numbering.
*/
void __init init_i8259_irqs (void)
{
int i;
request_resource(&ioport_resource, &pic1_io_resource);
request_resource(&ioport_resource, &pic2_io_resource);
init_8259A(0);
for (i = 0; i < 16; i++) {
irq_desc[i].status = IRQ_DISABLED;
irq_desc[i].action = 0;
irq_desc[i].depth = 1;
irq_desc[i].handler = &i8259A_irq_type;
}
setup_irq(2, &irq2);
}
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