Make PCI enumeration write more information

The PCI enumeration did, until now, only write a PCI device's address
into the device area. Now, it also writes the class and subclass.

i386/loader/src-asm/drivers/pci/enumerate.asm

@@ -58,9 +58,11 @@ pci_device_exists:
 
 ; Arguments:
 ;   [FURTHEST FROM EBP]
-;     3. U32            PCI Device Class & Subclass
+;     3. U16            PCI Device Class & Subclass
 ;                       (Higher byte: Class, lower byte: Subclass)
-;     2. U32            PCI Device Address
+;     2. U16            PCI Device Address
+;                       (Higher byte: Bus Address,
+;                       lower byte:  Device Address)
 ;     1. Ptr32          Pointer to PCI driver area of 65536 bytes
 ;   [NEAREST TO EBP]
 pci_append_device:
@@ -81,19 +83,21 @@ pci_append_device:
 
 .calculate_device_offset:
     ; Every device slot has 16 bytes, multiply index with 16
-    shl         cx,                     4
+    shl         ecx,                    4
     ; Point into driver device area (add device area start on top)
-    add         ecx,                    ebx
+    mov ebx, [ebp - 4]
-    add         ecx,                    PCI_DEVICE_COUNT_OFFSET
+    add         ebx,                    PCI_DEVICE_AREA_OFFSET
-    mov         ebx,                    ecx
+    add         ebx,                    ecx
 
 .set_device:
-    mov         ecx,                    [ebp - 8]
+    mov         cx,                     [ebp - 6]
-    mov         [ebx],                  ecx
+    mov         [ebx],                  cx
-    mov         ecx,                    [ebp - 12]
+    mov         cx,                     [ebp - 8]
-    mov         [ebx + 4],              ecx
+    mov         [ebx + 2],              cx
 
-increment_device_count:
+.increment_device_count:
+    mov ebx, [ebp - 4]
+    inc         word [ebx + PCI_DEVICE_COUNT_OFFSET]
 
 .epilog:
     mov         eax,                    [esi + (64 - 4)]
@@ -107,6 +111,68 @@ increment_device_count:
 
 
 
+; Arguments:
+;   [FURTHER FROM EBP]
+;     2.  U16           Device Number
+;     1.  U16           Bus Number
+;   [NEAREST TO EBP]
+;
+; Returns:
+;       ax             PCI Device Class & Subclass
+;                      (Higher byte: Class, lower byte: Subclass)
+pci_get_device_class_at_address:
+    push dword esi
+    sub esp, 64
+    mov esi, esp
+
+    mov [esi + (64 - 8)], ebx
+    mov [esi + (64 - 12)], ecx
+    mov [esi + (64 - 16)], edx
+    mov [esi + (64 - 20)], edi
+
+.create_address:
+    xor eax, eax
+    ; Enable Bit
+    or al, 1
+    ; Make space for 8 Reserved Bits and 8 Bytes of bus number.
+    shl eax, 15
+    ; Bus Number
+    mov al, [ebp - 2]
+    ; Device Number
+    shl eax, 5 ; Make space for device number
+    mov dl, [ebp - 4]
+    and dl, 0x1f
+    or al, dl
+    shl eax, 11
+
+    ; Include the register offset of the configuration space
+    ; register which contains the class and subclass
+    or eax, 8
+
+.input_output:
+
+    mov dx, PCI_CONFIG_ADDRESS_PORT
+    out dx, eax
+
+    mov dx, PCI_CONFIG_DATA_PORT
+    in eax, dx
+
+    ; Remove the parts of the register which aren't part of the
+    ; PCI class- and subclass-code
+    shr eax, 16
+
+.epilog:
+    mov ebx, [esi + (64 - 8)]
+    mov ecx, [esi + (64 - 12)]
+    mov edx, [esi + (64 - 16)]
+    mov edi, [esi + (64 - 20)]
+
+    add esp, 64
+    pop dword esi
+    ret
+
+
+
 ; Arguments:
 ;   [FURTHER FROM EBP]
 ;     2. U32            Bus Number          (0 .. 255)
@@ -130,6 +196,8 @@ pci_enumerate_bus:
     mov [esi + 4], dword 0
     mov eax, [ebp - 8]
     mov [esi + 8], eax
+    mov eax, [ebp - 4]
+    mov [esi + 12], eax
 .initialize_device_loop:
 
 .device_loop:
@@ -137,10 +205,12 @@ pci_enumerate_bus:
     jae .epilog
 
 .test_whether_device_exists:
-    push ebp
-    mov ebp, esp
     mov ah, [esi + 8]   ; Bus Number 
     mov al, [esi]       ; Device Number
+    mov [esi + 16], ax
+
+    push ebp
+    mov ebp, esp
     call pci_device_exists
     mov esp, ebp
     pop ebp
@@ -148,12 +218,32 @@ pci_enumerate_bus:
     cmp ax, 0
     je .no_device
 
-.call_append_device:
+.append_device:
+    mov al, [esi + 8]
+    mov ah, [esi]
+
+    ; Device Number in DX
+    xor dx, dx
+    mov dl, ah
+    xor ah, ah
+
+
     push ebp
     mov ebp, esp
-    push dword [esi + 8]
+    push ax
-    push dword 0xcafebabe
+    push dx
-    push dword 0xdeadbeef
+    call pci_get_device_class_at_address
+    mov esp, ebp
+    pop ebp
+
+    mov cx, ax
+    mov ax, [esi + 16]
+
+    push ebp
+    mov ebp, esp
+    push dword [esi + 12]
+    push ax
+    push cx
     call pci_append_device
     mov esp, ebp
     pop ebp
@@ -172,6 +262,7 @@ pci_enumerate_bus:
     mov ebx, [esi + (64 - 8)]
     mov ecx, [esi + (64 - 12)]
     mov edi, [esi + (64 - 20)]
+
     mov eax, [esi + 4]
 
     add esp, 64
@@ -203,6 +294,11 @@ pci_enumerate:
     mov edx, [ebp - 4]
     mov [esi + 4], edx
 
+    ; Set the device count to 0 explicitly, just for safety.
+    mov ebx, [ebp - 4]
+    add ebx, PCI_DEVICE_COUNT_OFFSET
+    mov [ebx], word 0
+
 .bus_loop:
     xor ecx, ecx
     mov [esi], dword 0