From f62fbefe5448fd90281e0c76378861e289ab669c Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@devjustinian.com>
Date: Mon, 16 Apr 2018 23:56:03 -0700
Subject: [PATCH] Parse APIC addresses out of ACPI tables.

---
 src/modules/main/acpi_tables.h      | 22 ++++++++----
 src/modules/main/device_manager.cpp | 53 ++++++++++++++++++++++++++++-
 src/modules/main/device_manager.h   | 10 ++++++
 3 files changed, 77 insertions(+), 8 deletions(-)

diff --git a/src/modules/main/acpi_tables.h b/src/modules/main/acpi_tables.h
index 64e094b..d50fa88 100644
--- a/src/modules/main/acpi_tables.h
+++ b/src/modules/main/acpi_tables.h
@@ -25,13 +25,6 @@ struct acpi_table_header
 	acpi_table_header header;
 
 
-struct acpi_xsdt
-{
-	TABLE_HEADER('XSDT');
-	acpi_table_header *headers[0];
-} __attribute__ ((packed));
-
-
 template <typename T>
 bool acpi_validate(const T *t) { return t->header.validate(T::type_id); }
 
@@ -41,3 +34,18 @@ size_t acpi_table_entries(const T *t, size_t size)
 	return (t->header.length - sizeof(T)) / size;
 }
 
+
+struct acpi_xsdt
+{
+	TABLE_HEADER('XSDT');
+	acpi_table_header *headers[0];
+} __attribute__ ((packed));
+
+struct acpi_apic
+{
+	TABLE_HEADER('APIC');
+	uint32_t local_address;
+	uint32_t flags;
+	uint8_t controller_data[0];
+} __attribute__ ((packed));
+
diff --git a/src/modules/main/device_manager.cpp b/src/modules/main/device_manager.cpp
index cdcdf85..1d95f42 100644
--- a/src/modules/main/device_manager.cpp
+++ b/src/modules/main/device_manager.cpp
@@ -47,7 +47,8 @@ acpi_table_header::validate(uint32_t expected_type) const
 	return !expected_type || (expected_type == type);
 }
 
-device_manager::device_manager(const void *root_table)
+device_manager::device_manager(const void *root_table) :
+	m_local_apic(nullptr)
 {
 	console *cons = console::get();
 
@@ -98,8 +99,58 @@ device_manager::load_xsdt(const acpi_xsdt *xsdt)
 
 		cons->puts(" ");
 		put_sig(cons, header->type);
+
 		kassert(header->validate(), "Table failed validation.");
+
+		switch (header->type) {
+		case acpi_apic::type_id:
+			load_apic(reinterpret_cast<const acpi_apic *>(header));
+			break;
+
+		default:
+			break;
+		}
 	}
 
 	cons->puts("\n");
 }
+
+template <typename T>
+T read_from(const uint8_t *p) { return *reinterpret_cast<const T *>(p); }
+
+void
+device_manager::load_apic(const acpi_apic *apic)
+{
+	console *cons = console::get();
+
+	m_local_apic = reinterpret_cast<uint8_t *>(apic->local_address);
+	cons->puts(" ");
+	cons->put_hex(apic->local_address);
+
+	uint8_t const *p = apic->controller_data;
+	uint8_t const *end = p + acpi_table_entries(apic, 1);
+
+	while (p < end) {
+		const uint8_t type = p[0];
+		const uint8_t length = p[1];
+
+		cons->puts(" ");
+		cons->put_hex(type);
+
+		switch (type) {
+		case 0: // Local APIC
+			break;
+
+		case 1: // I/O APIC
+			m_io_apic = reinterpret_cast<uint8_t *>(read_from<uint32_t>(p+4));
+			m_global_interrupt_base = read_from<uint32_t>(p+8);
+			cons->puts(" ");
+			cons->put_hex((uint64_t)m_io_apic);
+			cons->puts(" ");
+			cons->put_hex(m_global_interrupt_base);
+			break;
+		}
+
+		p += length;
+	}
+}
diff --git a/src/modules/main/device_manager.h b/src/modules/main/device_manager.h
index d8d9b62..5477ae4 100644
--- a/src/modules/main/device_manager.h
+++ b/src/modules/main/device_manager.h
@@ -1,6 +1,7 @@
 #pragma once
 
 struct acpi_xsdt;
+struct acpi_apic;
 
 class device_manager
 {
@@ -10,6 +11,15 @@ public:
 	device_manager() = delete;
 	device_manager(const device_manager &) = delete;
 
+	uint8_t * local_apic() const;
+	uint8_t * io_apic() const;
+
 private:
+	uint8_t *m_local_apic;
+	uint8_t *m_io_apic;
+
+	uint32_t m_global_interrupt_base;
+
 	void load_xsdt(const acpi_xsdt *xsdt);
+	void load_apic(const acpi_apic *apic);
 };