CbSerialPortLib.c

Go to the documentation of this file.

 
#include <Base.h>
#include <Coreboot.h>
 
#include <Library/BaseMemoryLib.h>
#include <Library/BlParseLib.h>
#include <Library/SerialPortLib.h>
 
// Upper nibble contains flags
#define CBMC_CURSOR_MASK  ((1 << 28) - 1)
#define CBMC_OVERFLOW     (1 << 31)
 
STATIC struct cbmem_console  *mCbConsole = NULL;
 
VOID *
FindCbTag (
  IN  UINT32  Tag
  );
 
RETURN_STATUS
EFIAPI
SerialPortInitialize (
  VOID
  )
{
  struct cb_cbmem_ref  *CbMemRef;
 
  // The coreboot table contains large structures as references
  CbMemRef = FindCbTag (CB_TAG_CBMEM_CONSOLE);
  if (CbMemRef == NULL) {
    return RETURN_DEVICE_ERROR;
  }
 
  mCbConsole = (VOID *)(UINTN)CbMemRef->cbmem_addr;  // Support PEI and DXE
  if (mCbConsole == NULL) {
    return RETURN_DEVICE_ERROR;
  }
 
  return RETURN_SUCCESS;
}
 
UINTN
EFIAPI
SerialPortWrite (
  IN UINT8  *Buffer,
  IN UINTN  NumberOfBytes
  )
{
  UINT32  Cursor;
  UINT32  Flags;
 
  if ((Buffer == NULL) || (NumberOfBytes == 0)) {
    return 0;
  }
 
  if (mCbConsole == NULL) {
    return 0;
  }
 
  Cursor = mCbConsole->cursor & CBMC_CURSOR_MASK;
  Flags  = mCbConsole->cursor & ~CBMC_CURSOR_MASK;
  if (Cursor >= mCbConsole->size) {
    // Already overflowed; bail out. TODO: Is this unnecessarily cautious?
    // - Supports old coreboot version with legacy overflow mechanism.
    return 0;
  }
 
  if (Cursor + NumberOfBytes > mCbConsole->size) {
    // Will overflow, zero cursor and set flag.
    Cursor = 0;
    Flags |= CBMC_OVERFLOW;
  }
 
  if (NumberOfBytes > mCbConsole->size) {
    // This one debug message is longer than the entire buffer. Truncate it.
    // - TODO: Is this unnecessarily cautious?
    NumberOfBytes = mCbConsole->size;
  }
 
  CopyMem (&mCbConsole->body[Cursor], Buffer, NumberOfBytes);
  Cursor += NumberOfBytes;
 
  if (Cursor == mCbConsole->size) {
    // Next message will overflow, zero cursor.
    // - Set flag preemptively. This could not be determined later.
    Cursor = 0;
    Flags |= CBMC_OVERFLOW;
  }
 
  mCbConsole->cursor = Flags | Cursor;
 
  return NumberOfBytes;
}
 
UINTN
EFIAPI
SerialPortRead (
  OUT UINT8  *Buffer,
  IN  UINTN  NumberOfBytes
  )
{
  return 0;
}
 
BOOLEAN
EFIAPI
SerialPortPoll (
  VOID
  )
{
  return FALSE;
}
 
RETURN_STATUS
EFIAPI
SerialPortSetControl (
  IN UINT32  Control
  )
{
  return RETURN_UNSUPPORTED;
}
 
RETURN_STATUS
EFIAPI
SerialPortGetControl (
  OUT UINT32  *Control
  )
{
  return RETURN_UNSUPPORTED;
}
 
RETURN_STATUS
EFIAPI
SerialPortSetAttributes (
  IN OUT UINT64              *BaudRate,
  IN OUT UINT32              *ReceiveFifoDepth,
  IN OUT UINT32              *Timeout,
  IN OUT EFI_PARITY_TYPE     *Parity,
  IN OUT UINT8               *DataBits,
  IN OUT EFI_STOP_BITS_TYPE  *StopBits
  )
{
  return RETURN_UNSUPPORTED;
}