Some virtual machine managers like kvmtool emulate the PC AT
Serial Port UART in the MMIO space so that architectures that
do not support I/O Mapped I/O can use the UART.
This patch adds MMIO support to the PC AT SerialPortLib.
PcdSerialUseMmio is used to select I/O or MMIO support.
If PcdSerialUseMmio is
TRUE - The value is read/written from MMIO space.
FALSE - The value is read/written from I/O space.
The Default is I/O space.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Sami Mujawar <[email protected]>
---
The changes can be seen at
https://github.com/samimujawar/edk2/commit/84f908387d2031def5d374759e7ad4cf90786c91
Notes:
v1:
- Add support to read/write from UART registers using MMIO access [SAMI]
PcAtChipsetPkg/Library/SerialIoLib/SerialIoLib.inf | 4 +
PcAtChipsetPkg/Library/SerialIoLib/SerialPortLib.c | 98 ++++++++++++++++----
2 files changed, 84 insertions(+), 18 deletions(-)
diff --git a/PcAtChipsetPkg/Library/SerialIoLib/SerialIoLib.inf
b/PcAtChipsetPkg/Library/SerialIoLib/SerialIoLib.inf
index
959d6e27c9812d201d44d9249070ab7758cbfe00..d0689793040fd930701b02dae51ff59ea16a10c4
100644
--- a/PcAtChipsetPkg/Library/SerialIoLib/SerialIoLib.inf
+++ b/PcAtChipsetPkg/Library/SerialIoLib/SerialIoLib.inf
@@ -2,6 +2,7 @@
# Library instance for SerialIo library class
#
# Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
# This program and the accompanying materials
# are licensed and made available under the terms and conditions of the BSD
License
# which accompanies this distribution. The full text of the license may be
found at
@@ -23,6 +24,7 @@ [Defines]
[Packages]
MdePkg/MdePkg.dec
+ MdeModulePkg/MdeModulePkg.dec
[LibraryClasses]
BaseLib
@@ -31,3 +33,5 @@ [LibraryClasses]
[Sources]
SerialPortLib.c
+[FixedPcd]
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio ## CONSUMES
diff --git a/PcAtChipsetPkg/Library/SerialIoLib/SerialPortLib.c
b/PcAtChipsetPkg/Library/SerialIoLib/SerialPortLib.c
index
d1a1c6a03facad09e781b5605e22a24e5f51c618..898e5f957aae998624189c6b538912da0439dfe8
100644
--- a/PcAtChipsetPkg/Library/SerialIoLib/SerialPortLib.c
+++ b/PcAtChipsetPkg/Library/SerialIoLib/SerialPortLib.c
@@ -2,6 +2,8 @@
UART Serial Port library functions
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+ Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
+
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD
License
which accompanies this distribution. The full text of the license may be
found at
@@ -57,6 +59,66 @@ UINT8 gParity = 0;
UINT8 gBreakSet = 0;
/**
+ Reads an 8-bit value from the serial port.
+
+ This function checks PcdSerialUseMmio to determine if I/O
+ mapped IO or Memory Mapped IO operations must be performed on
+ the serial port. It then uses the appropriate interface to
+ read the Value from the serial port.
+
+ If PcdSerialUseMmio is TRUE, then the value is read from MMIO space.
+ If PcdSerialUseMmio is FALSE, then the value is read from I/O space.
+
+ @param Address The UART register to read from.
+
+ @return The value read from the serial port.
+
+**/
+STATIC
+UINT8
+SerialPortRead8 (
+ IN UINTN Address
+)
+{
+ if (FixedPcdGetBool (PcdSerialUseMmio)) {
+ return MmioRead8 (Address);
+ }
+
+ return IoRead8 (Address);
+}
+
+/**
+ Writes an 8-bit value to the serial port.
+
+ This function checks PcdSerialUseMmio to determine if I/O
+ mapped IO or Memory Mapped IO operations must be performed on
+ the serial port. It then uses the appropriate interface to
+ write the Value to the serial port.
+
+ If PcdSerialUseMmio is TRUE, then the value is written to MMIO space.
+ If PcdSerialUseMmio is FALSE, then the value is written to I/O space.
+
+ @param Address The UART register to write.
+ @param Value The value to write to the I/O port.
+
+ @return The value written to the serial port.
+
+**/
+STATIC
+UINT8
+SerialPortWrite8 (
+ IN UINTN Address,
+ IN UINT8 Value
+)
+{
+ if (FixedPcdGetBool (PcdSerialUseMmio)) {
+ return MmioWrite8 (Address, Value);
+ }
+
+ return IoWrite8 (Address, Value);
+}
+
+/**
Initialize the serial device hardware.
If no initialization is required, then return RETURN_SUCCESS.
@@ -91,19 +153,19 @@ SerialPortInitialize (
// Set communications format
//
OutputData = (UINT8) ((DLAB << 7) | (gBreakSet << 6) | (gParity << 3) |
(gStop << 2) | Data);
- IoWrite8 (gUartBase + LCR_OFFSET, OutputData);
+ SerialPortWrite8 (gUartBase + LCR_OFFSET, OutputData);
//
// Configure baud rate
//
- IoWrite8 (gUartBase + BAUD_HIGH_OFFSET, (UINT8) (Divisor >> 8));
- IoWrite8 (gUartBase + BAUD_LOW_OFFSET, (UINT8) (Divisor & 0xff));
+ SerialPortWrite8 (gUartBase + BAUD_HIGH_OFFSET, (UINT8) (Divisor >> 8));
+ SerialPortWrite8 (gUartBase + BAUD_LOW_OFFSET, (UINT8) (Divisor & 0xff));
//
// Switch back to bank 0
//
OutputData = (UINT8) ( (gBreakSet << 6) | (gParity << 3) | (gStop << 2) |
Data);
- IoWrite8 (gUartBase + LCR_OFFSET, OutputData);
+ SerialPortWrite8 (gUartBase + LCR_OFFSET, OutputData);
return RETURN_SUCCESS;
}
@@ -148,9 +210,9 @@ SerialPortWrite (
// Wait for the serail port to be ready.
//
do {
- Data = IoRead8 ((UINT16) gUartBase + LSR_OFFSET);
+ Data = SerialPortRead8 ((UINT16) gUartBase + LSR_OFFSET);
} while ((Data & LSR_TXRDY) == 0);
- IoWrite8 ((UINT16) gUartBase, *Buffer++);
+ SerialPortWrite8 ((UINT16) gUartBase, *Buffer++);
}
return Result;
@@ -189,10 +251,10 @@ SerialPortRead (
// Wait for the serail port to be ready.
//
do {
- Data = IoRead8 ((UINT16) gUartBase + LSR_OFFSET);
+ Data = SerialPortRead8 ((UINT16) gUartBase + LSR_OFFSET);
} while ((Data & LSR_RXDA) == 0);
- *Buffer++ = IoRead8 ((UINT16) gUartBase);
+ *Buffer++ = SerialPortRead8 ((UINT16) gUartBase);
}
return Result;
@@ -220,7 +282,7 @@ SerialPortPoll (
//
// Read the serial port status.
//
- Data = IoRead8 ((UINT16) gUartBase + LSR_OFFSET);
+ Data = SerialPortRead8 ((UINT16) gUartBase + LSR_OFFSET);
return (BOOLEAN) ((Data & LSR_RXDA) != 0);
}
@@ -253,7 +315,7 @@ SerialPortSetControl (
//
// Read the Modem Control Register.
//
- Mcr = IoRead8 ((UINT16) gUartBase + MCR_OFFSET);
+ Mcr = SerialPortRead8 ((UINT16) gUartBase + MCR_OFFSET);
Mcr &= (~(MCR_DTRC | MCR_RTS));
if ((Control & EFI_SERIAL_DATA_TERMINAL_READY) ==
EFI_SERIAL_DATA_TERMINAL_READY) {
@@ -267,7 +329,7 @@ SerialPortSetControl (
//
// Write the Modem Control Register.
//
- IoWrite8 ((UINT16) gUartBase + MCR_OFFSET, Mcr);
+ SerialPortWrite8 ((UINT16) gUartBase + MCR_OFFSET, Mcr);
return RETURN_SUCCESS;
}
@@ -297,7 +359,7 @@ SerialPortGetControl (
//
// Read the Modem Status Register.
//
- Msr = IoRead8 ((UINT16) gUartBase + MSR_OFFSET);
+ Msr = SerialPortRead8 ((UINT16) gUartBase + MSR_OFFSET);
if ((Msr & MSR_CTS) == MSR_CTS) {
*Control |= EFI_SERIAL_CLEAR_TO_SEND;
@@ -318,7 +380,7 @@ SerialPortGetControl (
//
// Read the Modem Control Register.
//
- Mcr = IoRead8 ((UINT16) gUartBase + MCR_OFFSET);
+ Mcr = SerialPortRead8 ((UINT16) gUartBase + MCR_OFFSET);
if ((Mcr & MCR_DTRC) == MCR_DTRC) {
*Control |= EFI_SERIAL_DATA_TERMINAL_READY;
@@ -331,7 +393,7 @@ SerialPortGetControl (
//
// Read the Line Status Register.
//
- Lsr = IoRead8 ((UINT16) gUartBase + LSR_OFFSET);
+ Lsr = SerialPortRead8 ((UINT16) gUartBase + LSR_OFFSET);
if ((Lsr & LSR_TXRDY) == LSR_TXRDY) {
*Control |= EFI_SERIAL_OUTPUT_BUFFER_EMPTY;
@@ -470,19 +532,19 @@ SerialPortSetAttributes (
// Set communications format
//
OutputData = (UINT8) ((DLAB << 7) | (gBreakSet << 6) | (LcrParity << 3) |
(LcrStop << 2) | LcrData);
- IoWrite8 (gUartBase + LCR_OFFSET, OutputData);
+ SerialPortWrite8 (gUartBase + LCR_OFFSET, OutputData);
//
// Configure baud rate
//
- IoWrite8 (gUartBase + BAUD_HIGH_OFFSET, (UINT8) (Divisor >> 8));
- IoWrite8 (gUartBase + BAUD_LOW_OFFSET, (UINT8) (Divisor & 0xff));
+ SerialPortWrite8 (gUartBase + BAUD_HIGH_OFFSET, (UINT8) (Divisor >> 8));
+ SerialPortWrite8 (gUartBase + BAUD_LOW_OFFSET, (UINT8) (Divisor & 0xff));
//
// Switch back to bank 0
//
OutputData = (UINT8) ((gBreakSet << 6) | (LcrParity << 3) | (LcrStop << 2) |
LcrData);
- IoWrite8 (gUartBase + LCR_OFFSET, OutputData);
+ SerialPortWrite8 (gUartBase + LCR_OFFSET, OutputData);
return RETURN_SUCCESS;
}
--
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
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