wavepdd.c

Lido PXA270平台开发板的最新BSP,包括源代码

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/*++

$Workfile: WAVEPDD.C $

$Date: 2/03/04 10:11a $

Abstract:
      The PDD (Platform Dependent Driver) is responsible for
      communicating with the audio circuit to start and stop playback
      and/or recording and initialize and deinitialize the circuits. The
      API between the PDD and the MDD is called the DDSI (see "Key Routines"
      for more info).

Warning:
      This driver is specifically written for the UCB 1400 Audio Codec.  It is
      not a general AC 97 CODEC device driver.

Key Routines:

  PDD_AudioGetInterruptType -- This routine is part of the Interrupt Service Thread managed
    by the wave MDD.  Here interrupts are processed and DMA buffers are returned to the driver.
    That is, the DMA buffers are protected to keep the DMAC from reading or writing the buffers
    while the driver is processing them.  If the DMAC attempts to work on a buffer that is has
    not been posted by the driver an Interrupt will occur indicating write overflow or read
    under flow.  The DMAC engine will stall until the buffer is ready.  The status of reads or
    writes is returned to the MDD.

  private_WaveInStart, private_WaveOutStart -- These routines setup the DMAC for receive or
    transmit.  They copy data from application buffers (sent from or to the OS) to DMA buffers.
    The inital DMA buffers are then "posted" or setup for the DMAC engine to read or write.
    
  private_WaveInContinue, private_WaveOutContinue -- These routines continue processing
    input or output by moving data from or to application buffers from or to the DMAC buffers.
    Buffers are "posted" (marked for handling) by these routines.  If the DMAC engine attempts
    to read a buffer before it is posted, it will generate an interrupt and stall.  If the DMAC
    has stalled this routine will restart DMA.  (See also PDD_AudioGetInterruptType,
    private_AudioFillBuffer, and private_AudioGetBuffer).

  private_AudioFillBuffer,private_AudioGetBuffer -- These routines perform the actual copy and
    formatting of application sound data.  They copy the data from or to the DMAC buffers from
    or to the application buffers.  The data is also converted from the format of the audio
    Codec (stereo 16 bit) to the format requested by the application (such as monoral 8 bit).

  private_WaveInStop, private_WaveOutStop -- These routines stop the processing of audio buffers
    by indicating that no more data is available and setting the DMAC registers to stop xmit or
    recv of application data.

  PDD_WaveProc -- This routine actually processes the messages of the Device Driver Service
    Interface (DDSI).  The MDD sends these messages to the PDD for handling.

  PDD_AudioMessage -- This routine exposes a private interface to applications.

Key Structures:


Function Hierarchy:

     PDD_AudioGetInterruptType      xx
     PDD_AudioMessage               xx
     PDD_AudioInitialize            xx
         AudioPowerOn()             xx
         AudioOutMute();            xx
     PDD_AudioDeinitialize          xx
         PddpAudioDeallocateVm();   xx
     PDD_AudioPowerHandler          xx
     PDD_WaveProc                   xx
         WPDM_OPEN,                 xx
            private_WaveOpen        xx
         WPDM_CLOSE                 xx                  
         WPDM_START                 xx
             private_WaveInStart    xx
               private_AudioGetBuffer xx
             private_WaveOutStart   xx
               private_AudioFillBuffer !!
         WPDM_RESTART               xx
             private_WaveOutRestart xx
         WPDM_STOP                  xx
             private_WaveInStop     xx
             private_WaveOutStop    xx
         WPDM_CONTINUE              xx
             private_WaveInContinue xx
             private_WaveOutContinue xx
         WPDM_ENDOFDATA             xx
             private_WaveOutEndOfData xx
         WPDM_STANDBY                xx
             private_WaveStandby     --
         WPDM_PAUSE                  xx
             private_WaveOutPause    xx
         WPDM_GETDEVCAPS             xx
             private_WaveGetDevCaps  xx
         WPDM_GETVOLUME
         WPDM_SETVOLUME

Notes:



--*/

static const char __copyright[]= "Copyright