115 lines
3.3 KiB
C
115 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* PCI-related functions used by the EFI stub on multiple
|
|
* architectures.
|
|
*
|
|
* Copyright 2019 Google, LLC
|
|
*/
|
|
|
|
#include <linux/efi.h>
|
|
#include <linux/pci.h>
|
|
|
|
#include <asm/efi.h>
|
|
|
|
#include "efistub.h"
|
|
|
|
void efi_pci_disable_bridge_busmaster(void)
|
|
{
|
|
efi_guid_t pci_proto = EFI_PCI_IO_PROTOCOL_GUID;
|
|
unsigned long pci_handle_size = 0;
|
|
efi_handle_t *pci_handle = NULL;
|
|
efi_handle_t handle;
|
|
efi_status_t status;
|
|
u16 class, command;
|
|
int i;
|
|
|
|
status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL, &pci_proto,
|
|
NULL, &pci_handle_size, NULL);
|
|
|
|
if (status != EFI_BUFFER_TOO_SMALL) {
|
|
if (status != EFI_SUCCESS && status != EFI_NOT_FOUND)
|
|
efi_err("Failed to locate PCI I/O handles'\n");
|
|
return;
|
|
}
|
|
|
|
status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, pci_handle_size,
|
|
(void **)&pci_handle);
|
|
if (status != EFI_SUCCESS) {
|
|
efi_err("Failed to allocate memory for 'pci_handle'\n");
|
|
return;
|
|
}
|
|
|
|
status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL, &pci_proto,
|
|
NULL, &pci_handle_size, pci_handle);
|
|
if (status != EFI_SUCCESS) {
|
|
efi_err("Failed to locate PCI I/O handles'\n");
|
|
goto free_handle;
|
|
}
|
|
|
|
for_each_efi_handle(handle, pci_handle, pci_handle_size, i) {
|
|
efi_pci_io_protocol_t *pci;
|
|
unsigned long segment_nr, bus_nr, device_nr, func_nr;
|
|
|
|
status = efi_bs_call(handle_protocol, handle, &pci_proto,
|
|
(void **)&pci);
|
|
if (status != EFI_SUCCESS)
|
|
continue;
|
|
|
|
/*
|
|
* Disregard devices living on bus 0 - these are not behind a
|
|
* bridge so no point in disconnecting them from their drivers.
|
|
*/
|
|
status = efi_call_proto(pci, get_location, &segment_nr, &bus_nr,
|
|
&device_nr, &func_nr);
|
|
if (status != EFI_SUCCESS || bus_nr == 0)
|
|
continue;
|
|
|
|
/*
|
|
* Don't disconnect VGA controllers so we don't risk losing
|
|
* access to the framebuffer. Drivers for true PCIe graphics
|
|
* controllers that are behind a PCIe root port do not use
|
|
* DMA to implement the GOP framebuffer anyway [although they
|
|
* may use it in their implementation of Gop->Blt()], and so
|
|
* disabling DMA in the PCI bridge should not interfere with
|
|
* normal operation of the device.
|
|
*/
|
|
status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,
|
|
PCI_CLASS_DEVICE, 1, &class);
|
|
if (status != EFI_SUCCESS || class == PCI_CLASS_DISPLAY_VGA)
|
|
continue;
|
|
|
|
/* Disconnect this handle from all its drivers */
|
|
efi_bs_call(disconnect_controller, handle, NULL, NULL);
|
|
}
|
|
|
|
for_each_efi_handle(handle, pci_handle, pci_handle_size, i) {
|
|
efi_pci_io_protocol_t *pci;
|
|
|
|
status = efi_bs_call(handle_protocol, handle, &pci_proto,
|
|
(void **)&pci);
|
|
if (status != EFI_SUCCESS || !pci)
|
|
continue;
|
|
|
|
status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,
|
|
PCI_CLASS_DEVICE, 1, &class);
|
|
|
|
if (status != EFI_SUCCESS || class != PCI_CLASS_BRIDGE_PCI)
|
|
continue;
|
|
|
|
/* Disable busmastering */
|
|
status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,
|
|
PCI_COMMAND, 1, &command);
|
|
if (status != EFI_SUCCESS || !(command & PCI_COMMAND_MASTER))
|
|
continue;
|
|
|
|
command &= ~PCI_COMMAND_MASTER;
|
|
status = efi_call_proto(pci, pci.write, EfiPciIoWidthUint16,
|
|
PCI_COMMAND, 1, &command);
|
|
if (status != EFI_SUCCESS)
|
|
efi_err("Failed to disable PCI busmastering\n");
|
|
}
|
|
|
|
free_handle:
|
|
efi_bs_call(free_pool, pci_handle);
|
|
}
|