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