idt: add interruption handling

The Interruption Descriptor Table (IDT) is implemented in idt.{c,h} as
part of the core, but the setup and activation of the IDT and the
registration of specific interruption request handlers is part of
arch.{c,h}.  The request handlers are implemented in idt.s and
delegate to kernel_handle_interrupt.

2 files changed, 88 insertions, 3 deletions

diff --git a/core/idt.c b/core/idt.c
new file mode 100644
index 0000000..a20eb69
--- /dev/null
+++ b/core/idt.c
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2017 Robin Krahl <robin.krahl@ireas.org>
+ * 
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <garmos/arch.h>
+#include <garmos/gdt.h>
+#include <garmos/idt.h>
+#include <garmos/kernel.h>
+#include <garmos/types.h>
+
+#define IDT_GATE_COUNT 256
+
+struct idt_gate {
+	uint16_t handler_lo;
+	uint16_t gdt_offset;
+	uint8_t reserved;
+	uint8_t access;
+	uint16_t handler_hi;
+} __attribute__((packed));
+
+struct idt_gate idt[IDT_GATE_COUNT];
+
+struct idtp idtp = {
+	.limit = IDT_GATE_COUNT * sizeof(*idt) - 1,
+	.pointer = idt,
+};
+
+static void idt_set(uint8_t no, uint16_t offset, uint32_t handler,
+		uint8_t access, uint8_t flags);
+
+void idt_init(void)
+{
+	uint32_t offset = gdt_get_code_offset();
+	uint32_t i;
+	uint8_t *no = irqnos;
+	uint32_t *addr = irqhdls;
+
+	ker_dbg("Initializing IDT ...");
+
+	for (i = 0; i < IDT_GATE_COUNT; i++)
+		idt_set(i, offset, (uint32_t) &irqign, 0, 0xE);
+
+	for (; *no; no++, addr++) {
+		if (!*addr)
+			continue;
+		ker_dbg("Registerung IRQ handler ...");
+		idt_set(*no, offset, *addr, 0, 0xE);
+	}
+
+	idtset(idtp);
+}
+
+void idt_activate(void)
+{
+	idtact();
+}
+
+static void idt_set(uint8_t no, uint16_t offset, uint32_t handler,
+		uint8_t access, uint8_t flags)
+{
+	idt[no].handler_lo = handler & 0xFFFF;
+	idt[no].handler_hi = (handler >> 16) & 0xFFFF;
+	idt[no].gdt_offset = offset;
+	idt[no].reserved = 0;
+	idt[no].access = 0x80 | flags | ((access & 0x3) << 5);
+}
diff --git a/core/kernel.c b/core/kernel.c
index c159aef..098db12 100644
--- a/core/kernel.c
+++ b/core/kernel.c
@@ -12,24 +12,33 @@
  * more details.
  */
 
+#include <garmos/idt.h>
 #include <garmos/gdt.h>
 #include <garmos/kernel.h>
 #include <garmos/term.h>
 #include <garmos/types.h>
 
-
 void ker_dbg(char *s)
 {
 	term_print(s);
 	term_print("\n");
 }
 
+uint32_t kernel_handle_interrupt(uint8_t no, uint32_t esp)
+{
+	return esp;
+}
+
 void kernel_main(uint32_t multiboot, unsigned int *magicno)
 {
+	term_clear();
+
 	gdt_init();
+	idt_init();
+
+	idt_activate();
 
-	term_clear();
 	term_print("garmos 0.1.0\n\n");
 
-	while(1);
+	while (1);
 }