--- /dev/null
+/*
+ * This is the device-driver interface to the interrupt system.
+ * Copyright (c) 2001,2003 David H. Hovemeyer <daveho@cs.umd.edu>
+ * $Revision: 1.4 $
+ *
+ * This is free software. You are permitted to use,
+ * redistribute, and modify it as specified in the file "COPYING".
+ */
+
+#include <geekos/kassert.h>
+#include <geekos/idt.h>
+#include <geekos/io.h>
+#include <geekos/irq.h>
+
+#include <geekos/debug.h>
+
+/* ----------------------------------------------------------------------
+ * Private functions and data
+ * ---------------------------------------------------------------------- */
+
+/*
+ * Current IRQ mask.
+ * This should be kept up to date with setup.asm
+ * (which does the initial programming of the PICs).
+ */
+static ushort_t s_irqMask = 0xfffb;
+
+/*
+ * Get the master and slave parts of an IRQ mask.
+ */
+#define MASTER(mask) ((mask) & 0xff)
+#define SLAVE(mask) (((mask)>>8) & 0xff)
+
+
+/* ----------------------------------------------------------------------
+ * Public functions
+ * ---------------------------------------------------------------------- */
+
+/*
+ * Install a handler for given IRQ.
+ * Note that we don't unmask the IRQ.
+ */
+void Install_IRQ(int irq, Interrupt_Handler handler)
+{
+ Install_Interrupt_Handler(irq + FIRST_EXTERNAL_INT, handler);
+}
+
+/*
+ * Get current IRQ mask. Each bit position represents
+ * one of the 16 IRQ lines.
+ */
+ushort_t Get_IRQ_Mask(void)
+{
+ return s_irqMask;
+}
+
+/*
+ * Set the IRQ mask.
+ */
+void Set_IRQ_Mask(ushort_t mask)
+{
+ uchar_t oldMask, newMask;
+
+ oldMask = MASTER(s_irqMask);
+ newMask = MASTER(mask);
+ if (newMask != oldMask) {
+ Out_Byte(0x21, newMask);
+ }
+
+ oldMask = SLAVE(s_irqMask);
+ newMask = SLAVE(mask);
+ if (newMask != oldMask) {
+ Out_Byte(0xA1, newMask);
+ }
+
+ s_irqMask = mask;
+}
+
+/*
+ * Enable given IRQ.
+ */
+void Enable_IRQ(int irq)
+{
+ bool iflag = Begin_Int_Atomic();
+
+ KASSERT(irq >= 0 && irq < 16);
+ ushort_t mask = Get_IRQ_Mask();
+ mask &= ~(1 << irq);
+ Set_IRQ_Mask(mask);
+
+ End_Int_Atomic(iflag);
+}
+
+/*
+ * Disable given IRQ.
+ */
+void Disable_IRQ(int irq)
+{
+ bool iflag = Begin_Int_Atomic();
+
+ KASSERT(irq >= 0 && irq < 16);
+ ushort_t mask = Get_IRQ_Mask();
+ mask |= (1 << irq);
+ Set_IRQ_Mask(mask);
+
+ End_Int_Atomic(iflag);
+}
+
+/*
+ * Called by an IRQ handler to begin the interrupt.
+ * Currently a no-op.
+ */
+void Begin_IRQ(struct Interrupt_State* state)
+{
+ // SerialPrint("Begin_IRQ for interrupt 0x%x\n",state->intNum);
+}
+
+/*
+ * Called by an IRQ handler to end the interrupt.
+ * Sends an EOI command to the appropriate PIC(s).
+ */
+void End_IRQ(struct Interrupt_State* state)
+{
+ int irq = state->intNum - FIRST_EXTERNAL_INT;
+ End_IRQ_num(irq);
+}
+
+
+void End_IRQ_num(int irq) {
+ uchar_t command = 0x60 | (irq & 0x7);
+
+ if (irq < 8) {
+ /* Specific EOI to master PIC */
+ Out_Byte(0x20, command);
+ }
+ else {
+ /* Specific EOI to slave PIC, then to master (cascade line) */
+ Out_Byte(0xA0, command);
+ Out_Byte(0x20, 0x62);
+ }
+}
