handle IRQs

4 files changed, 132 insertions, 1 deletions

diff --git a/stage3/interrupts.c b/stage3/interrupts.c
index fa4e59d..e7b819e 100644
--- a/stage3/interrupts.c
+++ b/stage3/interrupts.c
@@ -2,6 +2,7 @@
 #include "halt.h"
 #include "font.h"
 #include "heap.h"
+#include "pic.h"
 
 extern u64 idt_entries[256]; // isr.asm
 
@@ -91,6 +92,10 @@ void interrupt_handler(interrupt_frame *frame)
 		dump_frame(frame);
 
 		halt();
+	} else if (frame->which-32 < 16) {
+		u64 irq = frame->which-32;
+		print("IRQ "); print_num(irq, 10, 0); print("\n");
+		ack_irq(irq);
 	} else {
 		print("Spurious Interrupt "); print_num(frame->which, 10, 0); print("\n");
 		dump_frame(frame);
diff --git a/stage3/main.c b/stage3/main.c
index 9ddcacf..630379b 100644
--- a/stage3/main.c
+++ b/stage3/main.c
@@ -6,6 +6,7 @@
 #include "font.h"
 #include "letters.h"
 #include "interrupts.h"
+#include "pic.h"
 
 void init()
 {
@@ -67,8 +68,10 @@ void init()
 	}
 
 	init_interrupts();
+	pic_init();
 
-	int a = 1/0;
+	unmask_irq(IRQ_PIT);
+	enable_irqs();
 
 	halt();
 }
diff --git a/stage3/pic.c b/stage3/pic.c
new file mode 100644
index 0000000..726a6da
--- /dev/null
+++ b/stage3/pic.c
@@ -0,0 +1,92 @@
+#include "pic.h"
+#include "io.h"
+
+void disable_irqs()
+{
+	asm volatile("cli");
+}
+
+void enable_irqs()
+{
+	asm volatile("sti");
+}
+
+void ack_irq(u8 lane)
+{
+	if (lane >= 8)
+		outb(IO_PIC2_CTRL, 1 << 5);
+
+	outb(IO_PIC1_CTRL, 1 << 5);
+}
+
+void unmask_irq(u8 lane)
+{
+	u8 port = IO_PIC1_DATA;
+
+	if (lane >= 8) {
+		port = IO_PIC2_DATA;
+		lane -= 8;
+	}
+
+	outb(port, inb(port) & ~(1 << lane));
+}
+
+void pic_init()
+{
+	typedef struct {
+		bool ic4 : 1;
+		bool single : 1;
+		bool addr_interval : 1;
+		bool level_triggered : 1;
+		bool init : 1;
+		unsigned int zeros : 3;
+	} __attribute__((packed)) pic_icw1;
+
+	u8 icw1 = BITCAST(((pic_icw1) {
+		.ic4 = true,
+		.single = false,
+		.addr_interval = false,
+		.level_triggered = false,
+		.init = true,
+		.zeros = 0,
+	}), pic_icw1, u8);
+
+	outb(IO_PIC1_CTRL, icw1);
+	outb(IO_PIC2_CTRL, icw1);
+
+	// map IRQs 0-15 to 0x20-0x2F
+	// 0x1F is the highest reserved interrupt
+	outb(IO_PIC1_DATA, 0x20);
+	outb(IO_PIC2_DATA, 0x28);
+
+	// pic2 is connected to IRQ2
+	outb(IO_PIC1_DATA, 1 << 2);
+	outb(IO_PIC2_DATA, 2);
+
+	typedef struct {
+		bool x86 : 1;
+		bool auto_eoi : 1;
+		bool primary_buffered : 1;
+		bool buffered : 1;
+		bool fully_nested : 1;
+		unsigned int zeros : 3;
+	} __attribute__((packed)) pic_icw4;
+
+	u8 icw4 = BITCAST(((pic_icw4) {
+		.x86 = true,
+		.auto_eoi = false,
+		.primary_buffered = false,
+		.buffered = false,
+		.fully_nested = false,
+		.zeros = 0,
+	}), pic_icw4, u8);
+
+	outb(IO_PIC1_DATA, icw4);
+	outb(IO_PIC2_DATA, icw4);
+
+	// mask all interrupts
+	outb(IO_PIC1_DATA, 0xff);
+	outb(IO_PIC2_DATA, 0xff);
+
+	disable_irqs();
+}
diff --git a/stage3/pic.h b/stage3/pic.h
new file mode 100644
index 0000000..eebe119
--- /dev/null
+++ b/stage3/pic.h
@@ -0,0 +1,31 @@
+#ifndef PIC_H
+#define PIC_H
+
+#include "def.h"
+
+typedef enum {
+	IRQ_PIT = 0,
+	IRQ_KEYBOARD,
+	IRQ_CASCADE,
+	IRQ_COM2,
+	IRQ_COM1,
+	IRQ_LPT2,
+	IRQ_FLOPPY,
+	IRQ_LPT1,
+	IRQ_CMOS_CLOCK,
+	IRQ_MOUSE,
+	IRQ_FREE1,
+	IRQ_FREE2,
+	IRQ_FREE3,
+	IRQ_FPU,
+	IRQ_ATA_HDD1,
+	IRQ_ATA_HDD2,
+} irq_lane;
+
+void disable_irqs();
+void enable_irqs();
+void unmask_irq(u8 lane);
+void ack_irq(u8 lane);
+void pic_init();
+
+#endif