How to multiplex the GPIO pins of the ADSP-BF706?

If it helps, Here is a function I wrote to provide the control I needed for GPIO or Peripherals connecting to the physical pin.

#define FOS_PORT_A_FER_REGISTER              0x20040000

#define FOS_PORT_A_MUX_REGISTER              0x20040030

#define FOS_PORT_B_FER_REGISTER              0x20040080

#define FOS_PORT_B_MUX_REGISTER              0x200400B0

#define FOS_PORT_C_FER_REGISTER              0x20040100

#define FOS_PORT_C_MUX_REGISTER              0x20040130

/*******************************************************************************
 *
 *  Function:       fosGpioPinControl
 *
 *  Inputs:         int gpio                 The Pin number to setup  0-47
 *                  int forceAsPeripheral    Flag that indicates GPIO or Peripheral  0 or 1
 *                  u32 peripheralMux        The mux value of the peripherail. 0,1,2 or 3
 *
 *  Outputs:        -1 for error, otherwise 0
 *
 *  Description:    This function will setup the pin to work as a GPIO or as
 *                  a peripheral.  If it is a peripheral, it will set the correct
 *                  mux value to get the correct peripheral out to the pin.
 *                  Pin number 0-15 portA 0:15, 16-31 portB 0:15, 32-47 portC 0:15
 *
 *  Cautions:       None
 *
 ******************************************************************************/
int fosGpioPinControl(int gpio, int forceAsPeripheral, u32 peripheralMux)
{
   u32              gpioMask;
   u32              gpioMuxMask;
   volatile u32*    gpioFerRegister;
   volatile u32*    gpioMuxRegister;
   u32              data;
   
   /* There is not any looping going on.  The while loop allows for
    * a convenient way to find the condition and then exit out.
    */
   do
   {
      if (gpio < 16)
      {  /* Port F is 0 to 15 */
         gpioFerRegister = (volatile u32*) FOS_PORT_A_FER_REGISTER;
         gpioMuxRegister = (volatile u32*) FOS_PORT_A_MUX_REGISTER;
         break;
      }
      if (gpio < 32)
      {/* Port G is 16 to 31 */
         gpioFerRegister = (volatile u32*) FOS_PORT_B_FER_REGISTER;
         gpioMuxRegister = (volatile u32*) FOS_PORT_B_MUX_REGISTER;
         gpio -= 16;
         break;
      }
      if (gpio < 48)
      {/* Port H is 32 to 47 */
         gpioFerRegister = (volatile u32*) FOS_PORT_C_FER_REGISTER;
         gpioMuxRegister = (volatile u32*) FOS_PORT_C_MUX_REGISTER;
         gpio -= 32;
         break;
      }
      return -1; /* The gpio value is out of range */
   } while(1); /* End fake while loop */
   
   gpioMask = (0x1 << gpio);
   gpioMuxMask = (0x3 << (gpio * 2));
   peripheralMux &= 0x3;  /* limit the mask to 2 bits */
   peripheralMux = (peripheralMux << (gpio * 2));
   
   if (forceAsPeripheral == 1)
   {
      /* Connect the peripherial to the external pin */
      data = *gpioFerRegister;
      data |= gpioMask;
      *gpioFerRegister =  data;
      asm("ssync;");
      
      /* Calculate and set the requested mux level */
      data = *gpioMuxRegister;
      /* Clear out old mux bits first */
      data &= ~(gpioMuxMask);
      /* Set GPIO pins for the requested mux function */
      data |= peripheralMux;
      *gpioMuxRegister =  data;
      asm("ssync;");
   }
   else
   {
      /* Connect the GPIO functionality to the external pin */
      data = *gpioFerRegister;
      data &= ~(gpioMask);
      *gpioFerRegister =  data;
      asm("ssync;");
   }
   return 0;
}

If it helps, Here is a function I wrote to provide the control I needed for GPIO or Peripherals connecting to the physical pin.

#define FOS_PORT_A_FER_REGISTER              0x20040000

#define FOS_PORT_A_MUX_REGISTER              0x20040030

#define FOS_PORT_B_FER_REGISTER              0x20040080

#define FOS_PORT_B_MUX_REGISTER              0x200400B0

#define FOS_PORT_C_FER_REGISTER              0x20040100

#define FOS_PORT_C_MUX_REGISTER              0x20040130

/*******************************************************************************
 *
 *  Function:       fosGpioPinControl
 *
 *  Inputs:         int gpio                 The Pin number to setup  0-47
 *                  int forceAsPeripheral    Flag that indicates GPIO or Peripheral  0 or 1
 *                  u32 peripheralMux        The mux value of the peripherail. 0,1,2 or 3
 *
 *  Outputs:        -1 for error, otherwise 0
 *
 *  Description:    This function will setup the pin to work as a GPIO or as
 *                  a peripheral.  If it is a peripheral, it will set the correct
 *                  mux value to get the correct peripheral out to the pin.
 *                  Pin number 0-15 portA 0:15, 16-31 portB 0:15, 32-47 portC 0:15
 *
 *  Cautions:       None
 *
 ******************************************************************************/
int fosGpioPinControl(int gpio, int forceAsPeripheral, u32 peripheralMux)
{
   u32              gpioMask;
   u32              gpioMuxMask;
   volatile u32*    gpioFerRegister;
   volatile u32*    gpioMuxRegister;
   u32              data;
   
   /* There is not any looping going on.  The while loop allows for
    * a convenient way to find the condition and then exit out.
    */
   do
   {
      if (gpio < 16)
      {  /* Port F is 0 to 15 */
         gpioFerRegister = (volatile u32*) FOS_PORT_A_FER_REGISTER;
         gpioMuxRegister = (volatile u32*) FOS_PORT_A_MUX_REGISTER;
         break;
      }
      if (gpio < 32)
      {/* Port G is 16 to 31 */
         gpioFerRegister = (volatile u32*) FOS_PORT_B_FER_REGISTER;
         gpioMuxRegister = (volatile u32*) FOS_PORT_B_MUX_REGISTER;
         gpio -= 16;
         break;
      }
      if (gpio < 48)
      {/* Port H is 32 to 47 */
         gpioFerRegister = (volatile u32*) FOS_PORT_C_FER_REGISTER;
         gpioMuxRegister = (volatile u32*) FOS_PORT_C_MUX_REGISTER;
         gpio -= 32;
         break;
      }
      return -1; /* The gpio value is out of range */
   } while(1); /* End fake while loop */
   
   gpioMask = (0x1 << gpio);
   gpioMuxMask = (0x3 << (gpio * 2));
   peripheralMux &= 0x3;  /* limit the mask to 2 bits */
   peripheralMux = (peripheralMux << (gpio * 2));
   
   if (forceAsPeripheral == 1)
   {
      /* Connect the peripherial to the external pin */
      data = *gpioFerRegister;
      data |= gpioMask;
      *gpioFerRegister =  data;
      asm("ssync;");
      
      /* Calculate and set the requested mux level */
      data = *gpioMuxRegister;
      /* Clear out old mux bits first */
      data &= ~(gpioMuxMask);
      /* Set GPIO pins for the requested mux function */
      data |= peripheralMux;
      *gpioMuxRegister =  data;
      asm("ssync;");
   }
   else
   {
      /* Connect the GPIO functionality to the external pin */
      data = *gpioFerRegister;
      data &= ~(gpioMask);
      *gpioFerRegister =  data;
      asm("ssync;");
   }
   return 0;
}