wm2wirelink.c

WM9713 audio codec driver for WinCE 5.0

/*-----------------------------------------------------------------------------
 * Copyright (c) Wolfson Microelectronics plc.  All rights reserved.
 *
 * This software as well as any related documentation is furnished under 
 * license and may only be used or copied in accordance with the terms of the 
 * license. The information in this file is furnished for informational use 
 * only, is subject to change without notice, and should not be construed as 
 * a commitment by Wolfson Microelectronics plc. Wolfson Microelectronics plc
 * assumes no responsibility or liability for any errors or inaccuracies that
 * may appear in this document or any software that may be provided in
 * association with this document. 
 *
 * Except as permitted by such license, no part of this document may be 
 * reproduced, stored in a retrieval system, or transmitted in any form or by 
 * any means without the express written consent of Wolfson Microelectronics plc. 
 *
 * $Id: WM2WireLink.c 2169 2005-09-20 14:14:47Z ib $
 *
 * This file encapsulates the 2-wire operations required by drivers for Wolfson 
 * chips.  It assumes the interface in WMPlatform2Wire.h is provided for the
 * specific platform/operating system.
 *
 * Warning:
 *  This driver is specifically written for Wolfson Codecs. It is not a 
 *  general CODEC device driver.
 *
 * -----------------------------------------------------------------------------*/

/*
 * IMPORTANT
 *
 * The functions in this file must obey two rules:
 *
 * 1. They do not use any memory other than stack space and parameters passed in.
 * 2. They do not make system calls, unless WMSystemCallsAllowed returns TRUE.
 *
 * All functions take a context parameter, which passes in pointers to the virtual
 * addresses of memory-mapped registers, and stores what type of device is being
 * accessed.
 * 
 * Some client functions provide shared memory via the v_pWMData member of the
 * context structure.  This cannot be relied on.
 */
 
/*
 * Include files
 */
#include "WMCommon.h"
#include "WMDevice.h"	
#include "WMControlLink.h"
#include "WMDeviceContext.h"
#include "WM2WireLink.h"
#include "WMPlatform2Wire.h"

#if WM_I2S

/*
 * Global definitions
 */
#define WRITE_ADDR(_addr)   (((_addr)<<1)|0)
#define READ_ADDR(_addr)    (((_addr)<<1)|1)

/*
 * Convert to/from network byte order (MSB first).
 */
#ifndef htons
#   define htons(_v)    ((_v & 0xFF00) >> 8) | ((_v & 0x00FF) << 8)
#   define ntohs(_v)    htons(_v)
#endif

/*
 * Private data
 */

/*
 * Function prototypes
 */

/*-----------------------------------------------------------------------------
 * Function:    WM2WireWrite
 *
 * Write the value to the given register.
 *
 * Parameters:
 *      hDevice     handle to the device (from WMOpenDevice)
 *      reg         register to write to
 *      value       value to write
 *
 * Returns:     WMSTATUS
 *      See WMStatus.h
 *---------------------------------------------------------------------------*/
WMSTATUS WM2WireWrite( WM_DEVICE_HANDLE hDevice,
                       WM_REGTYPE reg,
                       WM_REGVAL value
                     )
{
    WM_DEVICE_CONTEXT   *pDeviceContext = WMHANDLE_TO_DEVICE( hDevice );
    const WM_CHIPDEF    *pChipDef;
    WMSTATUS            status;
    unsigned short      data;

    WM_ASSERT( hDevice, pDeviceContext );

    /*
     * Look up our chipdef.
     */
    pChipDef = WMGetChipDef( hDevice );
    WM_ASSERT( hDevice, pChipDef );
    if ( !pChipDef )
    {
        status = WMS_NO_SUPPORTED_DEVICE;
    	goto error;
    }

    /* Make sure the fields have been set up */
    WM_ASSERT( hDevice, 0 != pChipDef->regAddrMask );
    WM_ASSERT( hDevice, 0 != pChipDef->regDataMask );

    /* Make sure the write fits in our 16-bit data variable */
    WM_ASSERT( hDevice, (reg << pChipDef->regAddrShift) <= 0xFFFF );

    /* At the moment we assume the address goes in the top */
    WM_ASSERT( hDevice, 0 != pChipDef->regAddrShift );
    WM_ASSERT( hDevice, pChipDef->regAddrMask > pChipDef->regDataMask );

    /*
     * Build up the register/data value.
     * It's made up of combined address and data - the widths of the two fields are
     * described in the chipdef.  For example a 7-bit address/9-bit data write would
     * be made up as follows:
     *      15     9 8      0
     *      +------+--------+
     *      | reg  |  data  |
     *      +------+--------+
     */
    data = ( (reg << pChipDef->regAddrShift) & pChipDef->regAddrMask ) | (value & pChipDef->regDataMask);

    /*
     * Now convert to network byte order (MSB first), since that's what
     * the 2-wire link uses.
     */
    data = htons( data );

    /*
     * And do the write.
     */
    status = WMPlatform2WireWrite( hDevice, 
                                   (unsigned char) WRITE_ADDR(pDeviceContext->codecAddress),
                                   (unsigned char *) &data,
                                   sizeof( data )
                                 );
    if ( WM_ERROR( status ) )
    {
        goto error;
    }

    /*
     * We're done.
     */    
    return WMS_SUCCESS;

error:
    return status;
}

/*-----------------------------------------------------------------------------
 * Function:    WM2WireReset
 *
 * Reset the registers to default settings.
 *
 * Parameters:
 *      hDevice             handle to the device (from WMOpenDevice)
 *
 * Returns:     WMSTATUS
 *      See WMStatus.h.
 *---------------------------------------------------------------------------*/
WMSTATUS WM2WireReset( WM_DEVICE_HANDLE hDevice )
{
    WMSTATUS            status;
    const WM_CHIPDEF    *pChipDef;
    WM_REGTYPE          resetReg;
    
    pChipDef = WMGetChipDef( hDevice );
    if ( !pChipDef )
    {
        status = WMS_NO_SUPPORTED_DEVICE;
        goto finish;
    }

    resetReg = pChipDef->resetReg;
    status = WMWrite( hDevice, resetReg, 0 );

finish:
    return status;
}

#endif /* WM_I2S */

/*------------------------------ END OF FILE ---------------------------------*/