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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | // 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); } |