From 29708067059985b545d96632fc8d85471b82308b Mon Sep 17 00:00:00 2001
From: Nigel <nigelbarink@hotmail.com>
Date: Mon, 11 Sep 2023 23:23:38 +0200
Subject: [PATCH] ACPI reading memory when mapped to higher half

---
 kernel/acpi/acpi.cpp | 37 +++++++++++++++++++++++++++++++------
 kernel/acpi/rsdp.cpp | 15 +++++++++++++--
 kernel/acpi/rsdp.h   |  5 ++---
 3 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/kernel/acpi/acpi.cpp b/kernel/acpi/acpi.cpp
index bc83d08..66d4c7a 100644
--- a/kernel/acpi/acpi.cpp
+++ b/kernel/acpi/acpi.cpp
@@ -1,20 +1,22 @@
 #include "acpi.h"
+#include "../../CoreLib/Memory.h"
+#include "../memory/VirtualMemoryManager.h"
+
 RSDPDescriptor* ACPI::rsd_ptr;
 RSCPDescriptor20* ACPI::rsd2_ptr;
 RSDT* ACPI::rsd_table;
 
-
+const int KERNEL_OFFSET = 0xC0000000;
 
 void ACPI::initialize(){
-
     // Find the Root System Description Pointer
     ACPI::rsd_ptr = FindRSD();
     printf("RSD address: 0x%x\n", ACPI::rsd_ptr);
-    //printRSD(rsd_ptr);
+    printRSD(rsd_ptr);
 
 
     if( rsd_ptr->Revision == 0 ){
-        // Using veriosn 1.0 of the ACPI specifiction
+        // Using version 1.0 of the ACPI specification
         int sum = rsd_ptr->Checksum;
         for (int i =0; i < sizeof(RSDPDescriptor) ; i++) {
             sum += ((char*)rsd_ptr)[i];
@@ -26,11 +28,34 @@ void ACPI::initialize(){
         else
             printf("invalid rsd\n");
 
+        printf("rsdp: 0x%x\n", rsd_ptr);
+
+        printf("0x%x address\n", (rsd_ptr->RsdtAddress));
+        Immediate_Map(rsd_ptr->RsdtAddress + KERNEL_OFFSET, rsd_ptr->RsdtAddress);
+
+        RSDT* rootSystemDescriptionTable = (RSDT*)(rsd_ptr->RsdtAddress + KERNEL_OFFSET);
+        //printf("0x%x Root System Descriptor address\n", rootSystemDescriptionTable);
+        // checksum it, but we'll ignore it for now
+        printf("signature ");
+        for (int i = 0; i < 4; i++) {
+            kterm_put( rootSystemDescriptionTable->h.Signature[i]);
+        }
+        kterm_put('\n');
+
+
+        int entries = (rootSystemDescriptionTable->h.Length - sizeof (rootSystemDescriptionTable->h)) /4;
+        printf("%d num entries\n", entries);
+        for( int i = 0; i < entries; i++){
+            ACPISDTHeader* h = (ACPISDTHeader*) rootSystemDescriptionTable->PointerToSDT + i ;
+            if(strncmp(h->Signature, "FACP", 4)){
+                printf("Found FACP Entry!\n");
+            }
+        }
+
 
-        //  Get the Root System Description Table NOTE: might need memory mapping
-        //RSDT* rootSystemDescriptionTable = (RSDT*) (rsd_ptr->RsdtAddress + 0xC0000000);
     } else{
         // parse it as of version2.0
+        printf("rsd2_ptr\n");
         ACPI::rsd2_ptr = (RSCPDescriptor20*)rsd_ptr;
     }
 
diff --git a/kernel/acpi/rsdp.cpp b/kernel/acpi/rsdp.cpp
index 3ed66e9..8882f7f 100644
--- a/kernel/acpi/rsdp.cpp
+++ b/kernel/acpi/rsdp.cpp
@@ -23,11 +23,22 @@ RSDPDescriptor* FindRSD(){
     char* memory_byte = (char*) 0x000f2e14;
     const void* string = "RSD PTR ";
 
-    for( ; (uint32_t) memory_byte < 0x00100000; memory_byte+=10){
+
+    for( ; (uint32_t) memory_byte < 0x0100000; memory_byte+=10){
         if( memcmp(memory_byte , string , 8 ) ==  0 ) {
         printf("RSD PTR found at 0x%x !\n", memory_byte);
+        return (RSDPDescriptor*) memory_byte;
         break;
         }
     }
-    return (RSDPDescriptor*) memory_byte;
+
+    memory_byte = (char*) 0x000E0000;
+    for ( ;(uint32_t) memory_byte < 0x000FFFFF; memory_byte += 1)
+    {
+        if( memcmp(memory_byte , string , 8 ) ==  0 ) {
+            printf("RSD PTR found at 0x%x !\n", memory_byte);
+            return (RSDPDescriptor*) memory_byte;
+            break;
+        }
+    }
 }
diff --git a/kernel/acpi/rsdp.h b/kernel/acpi/rsdp.h
index aef9445..77014fc 100644
--- a/kernel/acpi/rsdp.h
+++ b/kernel/acpi/rsdp.h
@@ -16,10 +16,9 @@ struct ACPISDTHeader{
     uint32_t CreatorRevision;
 };
 
-
 struct RSDT{
     struct ACPISDTHeader h;
-    uint32_t PointerToSDT[]; // Length of array : (header.Length - sizeof(header))/ 4
+    uint32_t *PointerToSDT; // Length of array : (header.Length - sizeof(header))/ 4
 }__attribute__((packed));
 
 
@@ -28,7 +27,7 @@ struct RSDPDescriptor {
     uint8_t Checksum ;
     char OEMID [6];
     uint8_t Revision;
-    RSDT* RsdtAddress;
+    uint32_t RsdtAddress;
 }__attribute__((packed));
 
 struct RSCPDescriptor20{