EmbeddedPkg/Library/GdbSerialLib/GdbSerialLib.c

   1 /** @file
   2   Basic serial IO abstraction for GDB
   3
   4   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7
   8 **/
   9
  10 #include <Uefi.h>
  11 #include <Library/GdbSerialLib.h>
  12 #include <Library/PcdLib.h>
  13 #include <Library/IoLib.h>
  14 #include <Library/DebugLib.h>
  15
  16 // ---------------------------------------------
  17 // UART Register Offsets
  18 // ---------------------------------------------
  19 #define BAUD_LOW_OFFSET    0x00
  20 #define BAUD_HIGH_OFFSET   0x01
  21 #define IER_OFFSET         0x01
  22 #define LCR_SHADOW_OFFSET  0x01
  23 #define FCR_SHADOW_OFFSET  0x02
  24 #define IR_CONTROL_OFFSET  0x02
  25 #define FCR_OFFSET         0x02
  26 #define EIR_OFFSET         0x02
  27 #define BSR_OFFSET         0x03
  28 #define LCR_OFFSET         0x03
  29 #define MCR_OFFSET         0x04
  30 #define LSR_OFFSET         0x05
  31 #define MSR_OFFSET         0x06
  32
  33 // ---------------------------------------------
  34 // UART Register Bit Defines
  35 // ---------------------------------------------
  36 #define LSR_TXRDY    0x20U
  37 #define LSR_RXDA     0x01U
  38 #define DLAB         0x01U
  39 #define ENABLE_FIFO  0x01U
  40 #define CLEAR_FIFOS  0x06U
  41
  42 // IO Port Base for the UART
  43 UINTN  gPort;
  44
  45 /**
  46   The constructor function initializes the UART.
  47
  48   @param  ImageHandle   The firmware allocated handle for the EFI image.
  49   @param  SystemTable   A pointer to the EFI System Table.
  50
  51   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
  52
  53 **/
  54 RETURN_STATUS
  55 EFIAPI
  56 GdbSerialLibConstructor (
  57   IN EFI_HANDLE        ImageHandle,
  58   IN EFI_SYSTEM_TABLE  *SystemTable
  59   )
  60 {
  61   UINT64  BaudRate;
  62   UINT8   DataBits;
  63   UINT8   Parity;
  64   UINT8   StopBits;
  65
  66   gPort = (UINTN)PcdGet32 (PcdGdbUartPort);
  67
  68   BaudRate = PcdGet64 (PcdGdbBaudRate);
  69   Parity   = PcdGet8 (PcdGdbParity);
  70   DataBits = PcdGet8 (PcdGdbDataBits);
  71   StopBits = PcdGet8 (PcdGdbStopBits);
  72
  73   return GdbSerialInit (BaudRate, Parity, DataBits, StopBits);
  74 }
  75
  76 /**
  77   Sets the baud rate, receive FIFO depth, transmit/receive time out, parity,
  78   data buts, and stop bits on a serial device. This call is optional as the serial
  79   port will be set up with defaults base on PCD values.
  80
  81   @param  BaudRate         The requested baud rate. A BaudRate value of 0 will use the
  82                            device's default interface speed.
  83   @param  Parity           The type of parity to use on this serial device. A Parity value of
  84                            DefaultParity will use the device's default parity value.
  85   @param  DataBits         The number of data bits to use on the serial device. A DataBits
  86                            value of 0 will use the device's default data bit setting.
  87   @param  StopBits         The number of stop bits to use on this serial device. A StopBits
  88                            value of DefaultStopBits will use the device's default number of
  89                            stop bits.
  90
  91   @retval EFI_SUCCESS      The device was configured.
  92   @retval EFI_DEVICE_ERROR The serial device could not be configured.
  93
  94 **/
  95 RETURN_STATUS
  96 EFIAPI
  97 GdbSerialInit (
  98   IN UINT64  BaudRate,
  99   IN UINT8   Parity,
 100   IN UINT8   DataBits,
 101   IN UINT8   StopBits
 102   )
 103 {
 104   UINTN  Divisor;
 105   UINT8  OutputData;
 106   UINT8  Data;
 107   UINT8  BreakSet = 0;
 108
 109   //
 110   // We assume the UART has been turned on to decode gPort address range
 111   //
 112
 113   //
 114   // Map 5..8 to 0..3
 115   //
 116   Data = (UINT8)(DataBits - (UINT8)5);
 117
 118   //
 119   // Calculate divisor for baud generator
 120   //
 121   Divisor = 115200/(UINTN)BaudRate;
 122
 123   //
 124   // Set communications format
 125   //
 126   OutputData = (UINT8)((DLAB << 7) | ((BreakSet << 6) | ((Parity << 3) | ((StopBits << 2) | Data))));
 127   IoWrite8 (gPort + LCR_OFFSET, OutputData);
 128
 129   //
 130   // Configure baud rate
 131   //
 132   IoWrite8 (gPort + BAUD_HIGH_OFFSET, (UINT8)(Divisor >> 8));
 133   IoWrite8 (gPort + BAUD_LOW_OFFSET, (UINT8)(Divisor & 0xff));
 134
 135   //
 136   // Switch back to bank 0
 137   //
 138   OutputData = (UINT8)((~DLAB<<7)|((BreakSet<<6)|((Parity<<3)|((StopBits<<2)| Data))));
 139   IoWrite8 (gPort + LCR_OFFSET, OutputData);
 140
 141   // Not sure this is the right place to enable the FIFOs....
 142   // We probably need the FIFO enabled to not drop input
 143   IoWrite8 (gPort + FCR_SHADOW_OFFSET, ENABLE_FIFO);
 144
 145   // Configure the UART hardware here
 146   return RETURN_SUCCESS;
 147 }
 148
 149 /**
 150   Check to see if a character is available from GDB. Do not read the character as that is
 151   done via GdbGetChar().
 152
 153   @return TRUE  - Character available
 154   @return FALSE - Character not available
 155
 156 **/
 157 BOOLEAN
 158 EFIAPI
 159 GdbIsCharAvailable (
 160   VOID
 161   )
 162 {
 163   UINT8  Data;
 164
 165   Data = IoRead8 (gPort + LSR_OFFSET);
 166
 167   return ((Data & LSR_RXDA) == LSR_RXDA);
 168 }
 169
 170 /**
 171   Get a character from GDB. This function must be able to run in interrupt context.
 172
 173   @return A character from GDB
 174
 175 **/
 176 CHAR8
 177 EFIAPI
 178 GdbGetChar (
 179   VOID
 180   )
 181 {
 182   UINT8  Data;
 183   CHAR8  Char;
 184
 185   // Wait for the serial port to be ready
 186   do {
 187     Data = IoRead8 (gPort + LSR_OFFSET);
 188   } while ((Data & LSR_RXDA) == 0);
 189
 190   Char = IoRead8 (gPort);
 191
 192   // Make this an DEBUG_INFO after we get everything debugged.
 193   DEBUG ((DEBUG_ERROR, "<%c<", Char));
 194   return Char;
 195 }
 196
 197 /**
 198   Send a character to GDB. This function must be able to run in interrupt context.
 199
 200
 201   @param  Char    Send a character to GDB
 202
 203 **/
 204 VOID
 205 EFIAPI
 206 GdbPutChar (
 207   IN  CHAR8  Char
 208   )
 209 {
 210   UINT8  Data;
 211
 212   // Make this an DEBUG_INFO after we get everything debugged.
 213   DEBUG ((DEBUG_ERROR, ">%c>", Char));
 214
 215   // Wait for the serial port to be ready
 216   do {
 217     Data = IoRead8 (gPort + LSR_OFFSET);
 218   } while ((Data & LSR_TXRDY) == 0);
 219
 220   IoWrite8 (gPort, Char);
 221 }
 222
 223 /**
 224   Send an ASCII string to GDB. This function must be able to run in interrupt context.
 225
 226
 227   @param  String    Send a string to GDB
 228
 229 **/
 230 VOID
 231 GdbPutString (
 232   IN CHAR8  *String
 233   )
 234 {
 235   while (*String != '\0') {
 236     GdbPutChar (*String);
 237     String++;
 238   }
 239 }