/*
* 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/interrupt.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/sysdev.h>
#include <asm/i8259.h>
#include <asm/io.h>
/*
* 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
*/
static int i8259A_auto_eoi;
DEFINE_SPINLOCK(i8259A_lock);
/* some platforms call this... */
void mask_and_ack_8259A(unsigned int);
static struct irq_chip i8259A_chip = {
.name = "XT-PIC",
.mask = disable_8259A_irq,
.unmask = enable_8259A_irq,
.mask_ack = mask_and_ack_8259A,
};
/*
* 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 cached_master_mask (cached_irq_mask)
#define cached_slave_mask (cached_irq_mask >> 8)
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_slave_mask, PIC_SLAVE_IMR);
else
outb(cached_master_mask, PIC_MASTER_IMR);
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_slave_mask, PIC_SLAVE_IMR);
else
outb(cached_master_mask, PIC_MASTER_IMR);
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(PIC_MASTER_CMD) & mask;
else
ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
spin_unlock_irqrestore(&i8259A_lock, flags);
return ret;
}
void make_8259A_irq(unsigned int irq)
{
disable_irq_nosync(irq);
set_irq_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
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,PIC_MASTER_CMD); /* ISR register */
value = inb(PIC_MASTER_CMD) & irqmask;
outb(0x0A,PIC_MASTER_CMD); /* back to the IRR register */
return value;
}
outb(0x0B,PIC_SLAVE_CMD); /* ISR register */
value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
outb(0x0A,PIC_SLAVE_CMD); /* 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 unnecessarily.
*
* Note that IRQ7 and IRQ15 (the two spurious IRQs
* usually resulting from 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(PIC_SLAVE_IMR); /* DUMMY - (do we need this?) */
outb(cached_slave_mask, PIC_SLAVE_IMR);
outb(0x60+(irq&7),PIC_SLAVE_CMD);/* 'Specific EOI' to slave */
outb(0x60+PIC_CASCADE_IR,PIC_MASTER_CMD); /* 'Specific EOI' to master-IRQ2 */
} else {
inb(PIC_MASTER_IMR); /* DUMMY - (do we need this?) */
outb(cached_master_mask, PIC_MASTER_IMR);
outb(0x60+irq,PIC_MASTER_CMD); /* 'Specific EOI to master */
}
#ifdef CONFIG_MIPS_MT_SMTC
if (irq_hwmask[irq] & ST0_IM)
set_c0_status(irq_hwmask[irq] & ST0_IM);
#endif /* CONFIG_MIPS_MT_SMTC */
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;
/*
* 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(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
spurious_irq_mask |= irqmask;
}
atomic_inc(&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;
}
}
static int i8259A_resume(struct sys_device *dev)
{
init_8259A(i8259A_auto_eoi);
return 0;
}
static int i8259A_shutdown(struct sys_device *dev)
{
/* Put the i8259A into a quiescent state that
* the kernel initialization code can get it
* out of.
*/
outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-1 */
return 0;
}
static struct sysdev_class i8259_sysdev_class = {
set_kset_name("i8259"),
.resume = i8259A_resume,
.shutdown = i8259A_shutdown,
};
static struct sys_device device_i8259A = {
.id = 0,
.cls = &i8259_sysdev_class,
};
static int __init i8259A_init_sysfs(void)
{
int error = sysdev_class_register(&i8259_sysdev_class);
if (!error)
error = sysdev_register(&device_i8259A);
return error;
}
device_initcall(i8259A_init_sysfs);
void __init init_8259A(int auto_eoi)
{
unsigned long flags;
i8259A_auto_eoi = auto_eoi;
spin_lock_irqsave(&i8259A_lock, flags);
outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */
/*
* outb_p - this has to work on a wide range of PC hardware.
*/
outb_p(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */
outb_p(I8259A_IRQ_BASE + 0, PIC_MASTER_IMR); /* ICW2: 8259A-1 IR0 mapped to I8259A_IRQ_BASE + 0x00 */
outb_p(1U << PIC_CASCADE_IR, PIC_MASTER_IMR); /* 8259A-1 (the master) has a slave on IR2 */
if (auto_eoi) /* master does Auto EOI */
outb_p(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
else /* master expects normal EOI */
outb_p(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
outb_p(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */
outb_p(I8259A_IRQ_BASE + 8, PIC_SLAVE_IMR); /* ICW2: 8259A-2 IR0 mapped to I8259A_IRQ_BASE + 0x08 */
outb_p(PIC_CASCADE_IR, PIC_SLAVE_IMR); /* 8259A-2 is a slave on master's IR2 */
outb_p(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); /* (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_chip.mask_ack = disable_8259A_irq;
else
i8259A_chip.mask_ack = mask_and_ack_8259A;
udelay(100); /* wait for 8259A to initialize */
outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */
spin_unlock_irqrestore(&i8259A_lock, flags);
}
/*
* IRQ2 is cascade interrupt to second interrupt controller
*/
static struct irqaction irq2 = {
no_action, 0, CPU_MASK_NONE, "cascade", NULL, NULL
};
static struct resource pic1_io_resource = {
.name = "pic1",
.start = PIC_MASTER_CMD,
.end = PIC_MASTER_IMR,
.flags = IORESOURCE_BUSY
};
static struct resource pic2_io_resource = {
.name = "pic2",
.start = PIC_SLAVE_CMD,
.end = PIC_SLAVE_IMR,
.flags = IORESOURCE_BUSY
};
/*
* On systems with i8259-style interrupt controllers we assume for
* driver compatibility reasons interrupts 0 - 15 to be the i8259
* 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++)
set_irq_chip_and_handler(i, &i8259A_chip, handle_level_irq);
setup_irq(PIC_CASCADE_IR, &irq2);
}
