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Add PCI register read utility 

The newly added utility routine reads the content of a known PCI
device's register given the index assigned to the device during
enumeration and the index of the register (and the PCI driver area,
but that is implied).
This commit is contained in:
Eric-Paul Ickhorn 2024-07-23 01:01:20 +02:00
parent 1285994cbf
commit 18e5b049a4
Signed by: epickh
GPG Key ID: 1358818BAA38B104
1 changed files with 68 additions and 0 deletions
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68
i386/loader/src-asm/drivers/pci/utility.asm Normal file
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; Arguments:
; [FURTHER FROM EBP]
; 3. U16 Register Index
; 2. U16 Device Index in device list
; 1. Ptr32 Pointer to PCI driver area
; [NEAREST TO EBP]
pci_read_register:
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
.check_device_index:
; todo: Boundary checks
.get_device:
xor ebx, ebx
mov bx, [ebp - 6]
shl ebx, 4
; Point into the driver's device area
add ebx, [ebp - 4]
add ebx, PCI_DEVICE_AREA_OFFSET
mov [esi], ebx
xor eax, eax
mov ax, [ebx]
mov [esi + 4], ah
mov [esi + 5], al
.make_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, [esi + 5]
; Device Number
shl eax, 5 ; Make space for device number
mov dl, [esi + 4]
and dl, 0x1f
or al, dl
shl eax, 9
or al, [ebp - 8]
shl eax, 2
.input_output:
mov dx, PCI_CONFIG_ADDRESS_PORT
out dx, eax
mov dx, PCI_CONFIG_DATA_PORT
in eax, dx
.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