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Interrupts: Do a specific EOI when using the PIC

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Before this change, we did a non-specific EOI, which could lead to
problems with other IRQs that are handled in the PIC. Since the original
8259A datasheet permits such functionality and we are not losing any
functionality, this change is acceptable even though we don't experience
problems with the EOI currently.
This commit is contained in:
Liav A 2020-03-20 16:52:14 +02:00 committed by Andreas Kling
parent 06e7fc9dee
commit cb676f1211
Notes: sideshowbarker 2024-07-19 08:09:10 +09:00 
Author: https://github.com/supercomputer7
Commit: https://github.com/SerenityOS/serenity/commit/cb676f12111
Pull-request: https://github.com/SerenityOS/serenity/pull/1361
Reviewed-by: https://github.com/awesomekling
1 changed files with 24 additions and 15 deletions
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39
Kernel/Interrupts/PIC.cpp
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@ -66,9 +66,9 @@ void PIC::disable(const GenericInterruptHandler& handler)
ASSERT(handler.interrupt_number() >= gsi_base() && handler.interrupt_number() < interrupt_vectors_count());
u8 irq = handler.interrupt_number();
u8 imr;
if (irq >= 8) {
if (irq & 8) {
imr = IO::in8(PIC1_CMD);
imr |= 1 << (irq - 8);
imr |= 1 << (irq & 7);
IO::out8(PIC1_CMD, imr);
} else {
imr = IO::in8(PIC0_CMD);
@ -88,16 +88,20 @@ PIC::PIC()
void PIC::spurious_eoi(const GenericInterruptHandler& handler) const
{
ASSERT(handler.type() == HandlerType::SpuriousInterruptHandler);
if (handler.interrupt_number() == 15)
eoi_interrupt(7);
if (handler.interrupt_number() == 7)
return;
if (handler.interrupt_number() == 15) {
IO::in8(PIC1_CMD); /* dummy read */
IO::out8(PIC0_CTL, 0x60 | (2));
}
}
bool PIC::is_vector_enabled(u8 irq) const
{
u8 imr;
if (irq >= 8) {
if (irq & 8) {
imr = IO::in8(PIC1_CMD);
imr &= 1 << (irq - 8);
imr &= 1 << (irq & 7);
} else {
imr = IO::in8(PIC0_CMD);
imr &= 1 << irq;
@ -118,9 +122,9 @@ void PIC::enable_vector(u8 irq)
InterruptDisabler disabler;
ASSERT(!is_hard_disabled());
u8 imr;
if (irq >= 8) {
if (irq & 8) {
imr = IO::in8(PIC1_CMD);
imr &= ~(1 << (irq - 8));
imr &= ~(1 << (irq & 7));
IO::out8(PIC1_CMD, imr);
} else {
imr = IO::in8(PIC0_CMD);
@ -140,9 +144,14 @@ void PIC::eoi(const GenericInterruptHandler& handler) const
void PIC::eoi_interrupt(u8 irq) const
{
if (irq >= 8)
IO::out8(PIC1_CTL, 0x20);
IO::out8(PIC0_CTL, 0x20);
if (irq & 8) {
IO::in8(PIC1_CMD); /* dummy read */
IO::out8(PIC1_CTL, 0x60 | (irq & 7));
IO::out8(PIC0_CTL, 0x60 | (2));
return;
}
IO::in8(PIC0_CMD); /* dummy read */
IO::out8(PIC0_CTL, 0x60 | irq);
}
void PIC::complete_eoi() const
@ -175,8 +184,8 @@ void PIC::remap(u8 offset)
IO::out8(PIC1_CMD, SLAVE_INDEX);
/* ICW4 (set x86 mode) */
IO::out8(PIC0_CMD, 0x01);
IO::out8(PIC1_CMD, 0x01);
IO::out8(PIC0_CMD, ICW4_8086);
IO::out8(PIC1_CMD, ICW4_8086);
// Mask -- start out with all IRQs disabled.
IO::out8(PIC0_CMD, 0xff);
@ -201,8 +210,8 @@ void PIC::initialize()
IO::out8(PIC1_CMD, SLAVE_INDEX);
/* ICW4 (set x86 mode) */
IO::out8(PIC0_CMD, 0x01);
IO::out8(PIC1_CMD, 0x01);
IO::out8(PIC0_CMD, ICW4_8086);
IO::out8(PIC1_CMD, ICW4_8086);
// Mask -- start out with all IRQs disabled.
IO::out8(PIC0_CMD, 0xff);