1 /** @file 2 3 Stateless fw_cfg library implementation. 4 5 Clients must call QemuFwCfgIsAvailable() first. 6 7 Copyright (C) 2013, Red Hat, Inc. 8 Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR> 9 10 This program and the accompanying materials are licensed and made available 11 under the terms and conditions of the BSD License which accompanies this 12 distribution. The full text of the license may be found at 13 http://opensource.org/licenses/bsd-license.php 14 15 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT 16 WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 17 **/ 18 19 #include <Library/DebugLib.h> 20 #include <Library/QemuFwCfgLib.h> 21 22 #include "QemuFwCfgLibInternal.h" 23 24 /** 25 Returns a boolean indicating if the firmware configuration interface 26 is available or not. 27 28 This function may change fw_cfg state. 29 30 @retval TRUE The interface is available 31 @retval FALSE The interface is not available 32 33 **/ 34 BOOLEAN 35 EFIAPI 36 QemuFwCfgIsAvailable ( 37 VOID 38 ) 39 { 40 UINT32 Signature; 41 UINT32 Revision; 42 43 QemuFwCfgSelectItem (QemuFwCfgItemSignature); 44 Signature = QemuFwCfgRead32 (); 45 DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature)); 46 QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion); 47 Revision = QemuFwCfgRead32 (); 48 DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision)); 49 if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) || 50 (Revision < 1) 51 ) { 52 DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n")); 53 return FALSE; 54 } 55 56 DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n")); 57 return TRUE; 58 } 59 60 61 /** 62 Returns a boolean indicating if the firmware configuration interface is 63 available for library-internal purposes. 64 65 This function never changes fw_cfg state. 66 67 @retval TRUE The interface is available internally. 68 @retval FALSE The interface is not available internally. 69 **/ 70 BOOLEAN 71 InternalQemuFwCfgIsAvailable ( 72 VOID 73 ) 74 { 75 // 76 // We always return TRUE, because the consumer of this library ought to have 77 // called QemuFwCfgIsAvailable before making other calls which would hit this 78 // path. 79 // 80 return TRUE; 81 } 82 83 /** 84 Returns a boolean indicating whether QEMU provides the DMA-like access method 85 for fw_cfg. 86 87 @retval TRUE The DMA-like access method is available. 88 @retval FALSE The DMA-like access method is unavailable. 89 **/ 90 BOOLEAN 91 InternalQemuFwCfgDmaIsAvailable ( 92 VOID 93 ) 94 { 95 return FALSE; 96 } 97
