Home | History | Annotate | Download | only in QemuFwCfgLib 
      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 #include "QemuFwCfgLibInternal.h"
     21 
     22 STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
     23 STATIC BOOLEAN mQemuFwCfgDmaSupported;
     24 
     25 
     26 /**
     27   Returns a boolean indicating if the firmware configuration interface
     28   is available or not.
     29 
     30   This function may change fw_cfg state.
     31 
     32   @retval    TRUE   The interface is available
     33   @retval    FALSE  The interface is not available
     34 
     35 **/
     36 BOOLEAN
     37 EFIAPI
     38 QemuFwCfgIsAvailable (
     39   VOID
     40   )
     41 {
     42   return InternalQemuFwCfgIsAvailable ();
     43 }
     44 
     45 
     46 RETURN_STATUS
     47 EFIAPI
     48 QemuFwCfgInitialize (
     49   VOID
     50   )
     51 {
     52   UINT32 Signature;
     53   UINT32 Revision;
     54 
     55   //
     56   // Enable the access routines while probing to see if it is supported.
     57   // For probing we always use the IO Port (IoReadFifo8()) access method.
     58   //
     59   mQemuFwCfgSupported = TRUE;
     60   mQemuFwCfgDmaSupported = FALSE;
     61 
     62   QemuFwCfgSelectItem (QemuFwCfgItemSignature);
     63   Signature = QemuFwCfgRead32 ();
     64   DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
     65   QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
     66   Revision = QemuFwCfgRead32 ();
     67   DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
     68   if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
     69       (Revision < 1)
     70      ) {
     71     DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
     72     mQemuFwCfgSupported = FALSE;
     73     return RETURN_SUCCESS;
     74   }
     75 
     76   if ((Revision & FW_CFG_F_DMA) == 0) {
     77     DEBUG ((DEBUG_INFO, "QemuFwCfg interface (IO Port) is supported.\n"));
     78   } else {
     79     mQemuFwCfgDmaSupported = TRUE;
     80     DEBUG ((DEBUG_INFO, "QemuFwCfg interface (DMA) is supported.\n"));
     81   }
     82   return RETURN_SUCCESS;
     83 }
     84 
     85 
     86 /**
     87   Returns a boolean indicating if the firmware configuration interface is
     88   available for library-internal purposes.
     89 
     90   This function never changes fw_cfg state.
     91 
     92   @retval    TRUE   The interface is available internally.
     93   @retval    FALSE  The interface is not available internally.
     94 **/
     95 BOOLEAN
     96 InternalQemuFwCfgIsAvailable (
     97   VOID
     98   )
     99 {
    100   return mQemuFwCfgSupported;
    101 }
    102 
    103 /**
    104   Returns a boolean indicating whether QEMU provides the DMA-like access method
    105   for fw_cfg.
    106 
    107   @retval    TRUE   The DMA-like access method is available.
    108   @retval    FALSE  The DMA-like access method is unavailable.
    109 **/
    110 BOOLEAN
    111 InternalQemuFwCfgDmaIsAvailable (
    112   VOID
    113   )
    114 {
    115   return mQemuFwCfgDmaSupported;
    116 }
    117