linux/arch/x86/kernel/i8259.c
Maciej W. Rozycki 60e684f0d6 x86/irq: Fix XT-PIC-XT-PIC in /proc/interrupts
Fix duplicate XT-PIC seen in /proc/interrupts on x86 systems
that make  use of 8259A Programmable Interrupt Controllers.
Specifically convert  output like this:

           CPU0
  0:      76573    XT-PIC-XT-PIC    timer
  1:         11    XT-PIC-XT-PIC    i8042
  2:          0    XT-PIC-XT-PIC    cascade
  4:          8    XT-PIC-XT-PIC    serial
  6:          3    XT-PIC-XT-PIC    floppy
  7:          0    XT-PIC-XT-PIC    parport0
  8:          1    XT-PIC-XT-PIC    rtc0
 10:        448    XT-PIC-XT-PIC    fddi0
 12:         23    XT-PIC-XT-PIC    eth0
 14:       2464    XT-PIC-XT-PIC    ide0
NMI:          0   Non-maskable interrupts
ERR:          0

to one like this:

           CPU0
  0:     122033    XT-PIC  timer
  1:         11    XT-PIC  i8042
  2:          0    XT-PIC  cascade
  4:          8    XT-PIC  serial
  6:          3    XT-PIC  floppy
  7:          0    XT-PIC  parport0
  8:          1    XT-PIC  rtc0
 10:        145    XT-PIC  fddi0
 12:         31    XT-PIC  eth0
 14:       2245    XT-PIC  ide0
NMI:          0   Non-maskable interrupts
ERR:          0

that is one like we used to have from ~2.2 till it was changed
sometime.

The rationale is there is no value in this duplicate
information, it  merely clutters output and looks ugly.  We only
have one handler for  8259A interrupts so there is no need to
give it a name separate from the  name already given to
irq_chip.

We could define meaningful names for handlers based on bits in
the ELCR  register on systems that have it or the value of the
LTIM bit we use in  ICW1 otherwise (hardcoded to 0 though with
MCA support gone), to tell  edge-triggered and level-triggered
inputs apart.  While that information  does not affect 8259A
interrupt handlers it could help people determine  which lines
are shareable and which are not.  That is material for a
separate change though.

Any tools that parse /proc/interrupts are supposed not to be
affected  since it was many years we used the format this change
converts back to.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.11.1410260147190.21390@eddie.linux-mips.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-28 12:01:08 +01:00

418 lines
11 KiB
C

#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/random.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/syscore_ops.h>
#include <linux/bitops.h>
#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/atomic.h>
#include <asm/timer.h>
#include <asm/hw_irq.h>
#include <asm/pgtable.h>
#include <asm/desc.h>
#include <asm/apic.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 void init_8259A(int auto_eoi);
static int i8259A_auto_eoi;
DEFINE_RAW_SPINLOCK(i8259A_lock);
/*
* 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;
static void mask_8259A_irq(unsigned int irq)
{
unsigned int mask = 1 << irq;
unsigned long flags;
raw_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);
raw_spin_unlock_irqrestore(&i8259A_lock, flags);
}
static void disable_8259A_irq(struct irq_data *data)
{
mask_8259A_irq(data->irq);
}
static void unmask_8259A_irq(unsigned int irq)
{
unsigned int mask = ~(1 << irq);
unsigned long flags;
raw_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);
raw_spin_unlock_irqrestore(&i8259A_lock, flags);
}
static void enable_8259A_irq(struct irq_data *data)
{
unmask_8259A_irq(data->irq);
}
static int i8259A_irq_pending(unsigned int irq)
{
unsigned int mask = 1<<irq;
unsigned long flags;
int ret;
raw_spin_lock_irqsave(&i8259A_lock, flags);
if (irq < 8)
ret = inb(PIC_MASTER_CMD) & mask;
else
ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
raw_spin_unlock_irqrestore(&i8259A_lock, flags);
return ret;
}
static void make_8259A_irq(unsigned int irq)
{
disable_irq_nosync(irq);
io_apic_irqs &= ~(1<<irq);
irq_set_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!
*/
static void mask_and_ack_8259A(struct irq_data *data)
{
unsigned int irq = data->irq;
unsigned int irqmask = 1 << irq;
unsigned long flags;
raw_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 */
}
raw_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;
}
}
struct irq_chip i8259A_chip = {
.name = "XT-PIC",
.irq_mask = disable_8259A_irq,
.irq_disable = disable_8259A_irq,
.irq_unmask = enable_8259A_irq,
.irq_mask_ack = mask_and_ack_8259A,
};
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 void i8259A_resume(void)
{
init_8259A(i8259A_auto_eoi);
restore_ELCR(irq_trigger);
}
static int i8259A_suspend(void)
{
save_ELCR(irq_trigger);
return 0;
}
static void i8259A_shutdown(void)
{
/* 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-2 */
}
static struct syscore_ops i8259_syscore_ops = {
.suspend = i8259A_suspend,
.resume = i8259A_resume,
.shutdown = i8259A_shutdown,
};
static void mask_8259A(void)
{
unsigned long flags;
raw_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 */
raw_spin_unlock_irqrestore(&i8259A_lock, flags);
}
static void unmask_8259A(void)
{
unsigned long flags;
raw_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 */
raw_spin_unlock_irqrestore(&i8259A_lock, flags);
}
static void init_8259A(int auto_eoi)
{
unsigned long flags;
unsigned char probe_val = ~(1 << PIC_CASCADE_IR);
unsigned char new_val;
i8259A_auto_eoi = auto_eoi;
raw_spin_lock_irqsave(&i8259A_lock, flags);
/*
* Check to see if we have a PIC.
* Mask all except the cascade and read
* back the value we just wrote. If we don't
* have a PIC, we will read 0xff as opposed to the
* value we wrote.
*/
outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */
outb(probe_val, PIC_MASTER_IMR);
new_val = inb(PIC_MASTER_IMR);
if (new_val != probe_val) {
printk(KERN_INFO "Using NULL legacy PIC\n");
legacy_pic = &null_legacy_pic;
raw_spin_unlock_irqrestore(&i8259A_lock, flags);
return;
}
outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
/*
* 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 */
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.irq_mask_ack = disable_8259A_irq;
else
i8259A_chip.irq_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 */
raw_spin_unlock_irqrestore(&i8259A_lock, flags);
}
/*
* make i8259 a driver so that we can select pic functions at run time. the goal
* is to make x86 binary compatible among pc compatible and non-pc compatible
* platforms, such as x86 MID.
*/
static void legacy_pic_noop(void) { };
static void legacy_pic_uint_noop(unsigned int unused) { };
static void legacy_pic_int_noop(int unused) { };
static int legacy_pic_irq_pending_noop(unsigned int irq)
{
return 0;
}
struct legacy_pic null_legacy_pic = {
.nr_legacy_irqs = 0,
.chip = &dummy_irq_chip,
.mask = legacy_pic_uint_noop,
.unmask = legacy_pic_uint_noop,
.mask_all = legacy_pic_noop,
.restore_mask = legacy_pic_noop,
.init = legacy_pic_int_noop,
.irq_pending = legacy_pic_irq_pending_noop,
.make_irq = legacy_pic_uint_noop,
};
struct legacy_pic default_legacy_pic = {
.nr_legacy_irqs = NR_IRQS_LEGACY,
.chip = &i8259A_chip,
.mask = mask_8259A_irq,
.unmask = unmask_8259A_irq,
.mask_all = mask_8259A,
.restore_mask = unmask_8259A,
.init = init_8259A,
.irq_pending = i8259A_irq_pending,
.make_irq = make_8259A_irq,
};
struct legacy_pic *legacy_pic = &default_legacy_pic;
static int __init i8259A_init_ops(void)
{
if (legacy_pic == &default_legacy_pic)
register_syscore_ops(&i8259_syscore_ops);
return 0;
}
device_initcall(i8259A_init_ops);