ArmPkg/Library/SemiHostingSerialPortLib/SerialPortLib.c

   1 /** @file
   2   Serial I/O Port library functions with no library constructor/destructor
   3
   4   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   5   Copyright (c) 2021, Arm Limited. All rights reserved.<BR>
   6
   7   SPDX-License-Identifier: BSD-2-Clause-Patent
   8
   9 **/
  10
  11 #include <Uefi.h>
  12 #include <Library/DebugLib.h>
  13 #include <Library/SemihostLib.h>
  14 #include <Library/SerialPortLib.h>
  15
  16 /*
  17
  18   Programmed hardware of Serial port.
  19
  20   @return    Always return EFI_UNSUPPORTED.
  21
  22 **/
  23 RETURN_STATUS
  24 EFIAPI
  25 SerialPortInitialize (
  26   VOID
  27   )
  28 {
  29   if (SemihostConnectionSupported ()) {
  30     return RETURN_SUCCESS;
  31   } else {
  32     return RETURN_UNSUPPORTED;
  33   }
  34 }
  35
  36 /**
  37   Write data to serial device.
  38
  39   @param  Buffer           Point of data buffer which need to be written.
  40   @param  NumberOfBytes    Number of output bytes which are cached in Buffer.
  41
  42   @retval 0                Write data failed.
  43   @retval !0               Actual number of bytes written to serial device.
  44
  45 **/
  46
  47 #define PRINT_BUFFER_SIZE       512
  48 #define PRINT_BUFFER_THRESHOLD  (PRINT_BUFFER_SIZE - 4)
  49
  50 UINTN
  51 EFIAPI
  52 SerialPortWrite (
  53   IN UINT8  *Buffer,
  54   IN UINTN  NumberOfBytes
  55   )
  56 {
  57   UINT8  PrintBuffer[PRINT_BUFFER_SIZE];
  58   UINTN  SourceIndex;
  59   UINTN  DestinationIndex;
  60   UINT8  CurrentCharacter;
  61
  62   SourceIndex      = 0;
  63   DestinationIndex = 0;
  64
  65   while (SourceIndex < NumberOfBytes) {
  66     CurrentCharacter = Buffer[SourceIndex++];
  67
  68     switch (CurrentCharacter) {
  69       case '\r':
  70         continue;
  71
  72       case '\n':
  73         PrintBuffer[DestinationIndex++] = ' ';
  74       // fall through
  75
  76       default:
  77         PrintBuffer[DestinationIndex++] = CurrentCharacter;
  78         break;
  79     }
  80
  81     if (DestinationIndex > PRINT_BUFFER_THRESHOLD) {
  82       PrintBuffer[DestinationIndex] = '\0';
  83       SemihostWriteString ((CHAR8 *)PrintBuffer);
  84
  85       DestinationIndex = 0;
  86     }
  87   }
  88
  89   if (DestinationIndex > 0) {
  90     PrintBuffer[DestinationIndex] = '\0';
  91     SemihostWriteString ((CHAR8 *)PrintBuffer);
  92   }
  93
  94   return NumberOfBytes;
  95 }
  96
  97 /**
  98   Read data from serial device and save the datas in buffer.
  99
 100   @param  Buffer           Point of data buffer which need to be written.
 101   @param  NumberOfBytes    Number of output bytes which are cached in Buffer.
 102
 103   @retval 0                Read data failed.
 104   @retval !0               Actual number of bytes read from serial device.
 105
 106 **/
 107 UINTN
 108 EFIAPI
 109 SerialPortRead (
 110   OUT UINT8  *Buffer,
 111   IN  UINTN  NumberOfBytes
 112   )
 113 {
 114   *Buffer = SemihostReadCharacter ();
 115   return 1;
 116 }
 117
 118 /**
 119   Check to see if any data is available to be read from the debug device.
 120
 121   @retval TRUE       At least one byte of data is available to be read
 122   @retval FALSE      No data is available to be read
 123
 124 **/
 125 BOOLEAN
 126 EFIAPI
 127 SerialPortPoll (
 128   VOID
 129   )
 130 {
 131   // Since SemiHosting read character is blocking always say we have a char ready?
 132   return SemihostConnectionSupported ();
 133 }