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DEFINITIONS
This source file includes following definitions.
- disable_8259A_irq
- enable_8259A_irq
- i8259A_irq_pending
- make_8259A_irq
- i8259A_irq_real
- mask_and_ack_8259A
- restore_ELCR
- save_ELCR
- i8259A_resume
- i8259A_suspend
- i8259A_shutdown
- i8259A_init_sysfs
- mask_8259A
- unmask_8259A
- init_8259A
#include <linux/linkage.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/sysdev.h>
#include <linux/bitops.h>
#include <asm/acpi.h>
#include <asm/atomic.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/timer.h>
#include <asm/hw_irq.h>
#include <asm/pgtable.h>
#include <asm/delay.h>
#include <asm/desc.h>
#include <asm/apic.h>
#include <asm/arch_hooks.h>
#include <asm/i8259.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.
*/
static int i8259A_auto_eoi;
DEFINE_SPINLOCK(i8259A_lock);
static void mask_and_ack_8259A(unsigned int);
struct irq_chip i8259A_chip = {
.name = "XT-PIC",
.mask = disable_8259A_irq,
.disable = 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,
*/
unsigned int cached_irq_mask = 0xffff;
/*
* Not all IRQs can be routed through the IO-APIC, eg. on certain (older)
* boards the timer interrupt is not really connected to any IO-APIC pin,
* it's fed to the master 8259A's IR0 line only.
*
* Any '1' bit in this mask means the IRQ is routed through the IO-APIC.
* this 'mixed mode' IRQ handling costs nothing because it's only used
* at IRQ setup time.
*/
unsigned long io_apic_irqs;
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);
io_apic_irqs &= ~(1<<irq);
set_irq_chip_and_handler_name(irq, &i8259A_chip, handle_level_irq,
"XT");
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!
*/
static 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);
/* 'Specific EOI' to slave */
outb(0x60+(irq&7), PIC_SLAVE_CMD);
/* 'Specific EOI' to master-IRQ2 */
outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD);
} 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 */
}
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 char irq_trigger[2];
/**
* ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ
*/
static void restore_ELCR(char *trigger)
{
outb(trigger[0], 0x4d0);
outb(trigger[1], 0x4d1);
}
static void save_ELCR(char *trigger)
{
/* IRQ 0,1,2,8,13 are marked as reserved */
trigger[0] = inb(0x4d0) & 0xF8;
trigger[1] = inb(0x4d1) & 0xDE;
}
static int i8259A_resume(struct sys_device *dev)
{
init_8259A(i8259A_auto_eoi);
restore_ELCR(irq_trigger);
return 0;
}
static int i8259A_suspend(struct sys_device *dev, pm_message_t state)
{
save_ELCR(irq_trigger);
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 = {
.name = "i8259",
.suspend = i8259A_suspend,
.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 mask_8259A(void)
{
unsigned long flags;
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 */
spin_unlock_irqrestore(&i8259A_lock, flags);
}
void unmask_8259A(void)
{
unsigned long flags;
spin_lock_irqsave(&i8259A_lock, flags);
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);
}
void 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_pic - this has to work on a wide range of PC hardware.
*/
outb_pic(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */
/* ICW2: 8259A-1 IR0-7 mapped to 0x30-0x37 on x86-64,
to 0x20-0x27 on i386 */
outb_pic(IRQ0_VECTOR, PIC_MASTER_IMR);
/* 8259A-1 (the master) has a slave on IR2 */
outb_pic(1U << PIC_CASCADE_IR, PIC_MASTER_IMR);
if (auto_eoi) /* master does Auto EOI */
outb_pic(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
else /* master expects normal EOI */
outb_pic(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
outb_pic(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */
/* ICW2: 8259A-2 IR0-7 mapped to IRQ8_VECTOR */
outb_pic(IRQ8_VECTOR, PIC_SLAVE_IMR);
/* 8259A-2 is a slave on master's IR2 */
outb_pic(PIC_CASCADE_IR, PIC_SLAVE_IMR);
/* (slave's support for AEOI in flat mode is to be investigated) */
outb_pic(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR);
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);
}