[PATCH 1/1] MdeModulePkg: BaseSerialPortLib16550: Add Mmio32 support

[tien.hock.loh@intel.com]

From: "Tien Hock, Loh" <tien.hock.loh@intel.com>

Some busses doesn't allow 8 bit MMIO read/write, this adds support for
32 bits read/write

Signed-off-by: "Tien Hock, Loh" <tien.hock.loh@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>

--
v2:
- Updates the Pcd name to PcdSerialMmio32BitAccess and access 32 bits
register if PcdSerialUseMmio and PcdSerialMmio32BitAccess is set
---
 .../BaseSerialPortLib16550/BaseSerialPortLib16550.c      | 16 ++++++++--------
 .../BaseSerialPortLib16550/BaseSerialPortLib16550.inf    |  2 +-
 MdeModulePkg/MdeModulePkg.dec                            | 12 +++++++-----
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.c b/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.c
index b242b23..f90fb55 100644
--- a/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.c
+++ b/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.c
@@ -76,10 +76,10 @@ SerialPortReadRegister (
   UINTN  Offset
   )
 {
-  if (PcdGetBool (PcdSerialUseMmio32)) {
-    return (UINT8) MmioRead32 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
-  }
-  else if (PcdGetBool (PcdSerialUseMmio)) {
+  if (PcdGetBool (PcdSerialUseMmio)) {
+    if (PcdGetBool (PcdSerialMmio32BitAccess)) {
+      return (UINT8) MmioRead32 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
+    }
     return MmioRead8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
   } else {
     return IoRead8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
@@ -106,10 +106,10 @@ SerialPortWriteRegister (
   UINT8  Value
   )
 {
-  if (PcdGetBool (PcdSerialUseMmio32)) {
-    return MmioWrite32 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), (UINT8)Value);
-  }
-  else if (PcdGetBool (PcdSerialUseMmio)) {
+  if (PcdGetBool (PcdSerialUseMmio)) {
+    if (PcdGetBool (PcdSerialMmio32BitAccess)) {
+      return (UINT8) MmioWrite32 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), (UINT8)Value);
+    }
     return MmioWrite8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), Value);
   } else {
     return IoWrite8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), Value);
diff --git a/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.inf b/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.inf
index 575728a..c03d90d 100644
--- a/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.inf
+++ b/MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.inf
@@ -29,7 +29,7 @@
   BaseSerialPortLib16550.c
 
 [Pcd]
-  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio32               ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialMmio32BitAccess         ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio                 ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseHardwareFlowControl  ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdSerialDetectCable             ## SOMETIMES_CONSUMES
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 4e53625..f868850 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -1170,11 +1170,13 @@
   # @Prompt Serial port registers use MMIO.
   gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio|FALSE|BOOLEAN|0x00020000
 
-  ## Indicates the 16550 serial port registers are in MMIO 32 bit space, or in I/O space. Default is I/O space.<BR><BR>
-  #   TRUE  - 16550 serial port registers are in MMIO 32 bit space.<BR>
-  #   FALSE - 16550 serial port registers are in I/O space.<BR>
-  # @Prompt Serial port registers use MMIO.
-  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio32|FALSE|BOOLEAN|0x00020007
+  ## Indicates the access mode for 16550 serial port registers when they are in MMIO space.
+  # The PCD is only valid if PcdSerialUseMmio is set to TRUE.
+  # Default is 8-bit access mode.<BR><BR>
+  #   TRUE  - 16550 serial port MMIO registers are accessed in 32-bit width.<BR>
+  #   FALSE - 16550 serial port MMIO registers are accessed in 8-bit width.<BR>
+  # @Prompt Serial port MMIO registers access mode.
+  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialMmio32BitAccess|FALSE|BOOLEAN|0x00020007
 
   ## Indicates if the 16550 serial port hardware flow control will be enabled. Default is FALSE.<BR><BR>
   #   TRUE  - 16550 serial port hardware flow control will be enabled.<BR>
-- 
2.2.2