From f0e6a35941ab9087a77db3a1bf4b291c2c0b1cb4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Fri, 23 Feb 2018 13:31:55 +0100
Subject: [PATCH] Find and read ACPI tables

---
 src/kernel/boot/kmain.c   |  3 ++
 src/kernel/drivers/acpi.c | 81 +++++++++++++++++++++++++++++++++++++++
 src/kernel/include/smp.h  |  3 ++
 3 files changed, 87 insertions(+)
 create mode 100644 src/kernel/drivers/acpi.c
 create mode 100644 src/kernel/include/smp.h

diff --git a/src/kernel/boot/kmain.c b/src/kernel/boot/kmain.c
index dbbd180..7d3bd0a 100644
--- a/src/kernel/boot/kmain.c
+++ b/src/kernel/boot/kmain.c
@@ -7,6 +7,7 @@
 #include <interrupts.h>
 #include <process.h>
 #include <scheduler.h>
+#include <smp.h>
 
 void thread_function()
 {
@@ -30,6 +31,8 @@ void kmain(uint64_t multiboot_magic, void *multiboot_data)
 
   cpu_init();
 
+  acpi_init();
+
   struct process *p1 = new_process((void (*)(void))0x10000);
   procmm_brk(p1, (void *)0x10100);
   memcpy_to_p4(p1->P4, (void *)0x10000, (void *)(uintptr_t)thread_function, 100);
diff --git a/src/kernel/drivers/acpi.c b/src/kernel/drivers/acpi.c
new file mode 100644
index 0000000..8ee5c0c
--- /dev/null
+++ b/src/kernel/drivers/acpi.c
@@ -0,0 +1,81 @@
+#include <smp.h>
+#include <memory.h>
+#include <debug.h>
+
+struct rsdp
+{
+  uint8_t signature[8];
+  uint8_t checksum;
+  uint8_t OEMID[6];
+  uint8_t revision;
+  uint32_t rsdt;
+  uint32_t length;
+  uint64_t xsdt;
+  uint8_t checksum2;
+  uint8_t _[3];
+}__attribute__((packed));
+
+struct sdt
+{
+  uint8_t signature[4];
+  uint32_t len;
+  uint8_t revision;
+  uint8_t checksum;
+  uint8_t OEMID[6];
+  uint8_t table_ID[8];
+  uint32_t OEM_revision;
+  uint32_t creator;
+  uint32_t creator_rev;
+  uint8_t data[];
+}__attribute__((packed));
+
+static struct rsdp *find_rsdp()
+{
+  uintptr_t ebda_start = *(uint16_t *)P2V(0x40e);
+  uintptr_t ebda_end = ebda_start + 1024;
+
+  void *p = P2V(ebda_start);
+  while(p < P2V(ebda_end))
+  {
+    if(!memcmp(p, "RSD PTR ", 8))
+    {
+      debug_info("RSDP found at:%x\n", p);
+      return p;
+    }
+    p = incptr(p, 16);
+  }
+
+  p = P2V(0xE0000);
+  while(p < P2V(0xFFFFF))
+  {
+    if(!memcmp(p, "RSD PTR ", 8))
+    {
+      debug_info("RSDP found at:%x\n", p);
+      return p;
+    }
+    p = incptr(p, 16);
+  }
+
+  return 0;
+}
+
+static void parse_sdt(struct sdt *sdt, uint8_t revision)
+{
+  uint32_t *p32 = (void *)sdt->data;
+  uint64_t *p64 = (void *)sdt->data;
+  int entries = (sdt->len - sizeof(struct sdt)) / (revision ? 8 : 4);
+  for(int i = 0; i < entries; i++)
+  {
+    struct sdt *table = P2V(revision ? p64[i] : p32[i]);
+    debug_info("Found table: ");
+    debug_putsn((char *)table->signature, 4);
+    debug_printf("\n");
+  }
+}
+
+void acpi_init()
+{
+  struct rsdp *rsdp = find_rsdp();
+  struct sdt *s = P2V(rsdp->revision ? rsdp->xsdt : rsdp->rsdt);
+  parse_sdt(s, rsdp->revision);
+}
diff --git a/src/kernel/include/smp.h b/src/kernel/include/smp.h
new file mode 100644
index 0000000..2ab42f7
--- /dev/null
+++ b/src/kernel/include/smp.h
@@ -0,0 +1,3 @@
+#pragma once
+
+void acpi_init();