xuartns550_format.c

powerpc405下linux的串口驱动程序

/* $Id: xuartns550_format.c,v 1.1 2006/02/17 22:43:40 moleres Exp $ */
/*****************************************************************************
*
*       XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS"
*       AS A COURTESY TO YOU, SOLELY FOR USE IN DEVELOPING PROGRAMS AND
*       SOLUTIONS FOR XILINX DEVICES.  BY PROVIDING THIS DESIGN, CODE,
*       OR INFORMATION AS ONE POSSIBLE IMPLEMENTATION OF THIS FEATURE,
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*       INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
*       FOR A PARTICULAR PURPOSE.
*
*       (c) Copyright 2002 Xilinx Inc.
*       All rights reserved.
*
*****************************************************************************/
/****************************************************************************/
/**
*
* @file xuartns550_format.c
*
* This file contains the data format functions for the 16450/16550 UART driver.
* The data format functions allow the baud rate, number of data bits, number
* of stop bits and parity to be set and retrieved.
*
* <pre>
* MODIFICATION HISTORY:
*
* Ver   Who  Date     Changes
* ----- ---- -------- -----------------------------------------------
* 1.00b jhl  03/11/02 Repartitioned driver for smaller files.
* 1.00b rmm  05/15/03 Fixed diab compiler warnings.
* </pre>
*
*****************************************************************************/

/***************************** Include Files ********************************/

#include "xstatus.h"
#include "xuartns550.h"
#include "xuartns550_i.h"
#include "xio.h"

/************************** Constant Definitions ****************************/


/**************************** Type Definitions ******************************/


/***************** Macros (Inline Functions) Definitions ********************/


/************************** Variable Definitions ****************************/


/************************** Function Prototypes *****************************/


/****************************************************************************/
/**
*
* Sets the data format for the specified UART. The data format includes the
* baud rate, number of data bits, number of stop bits, and parity. It is the
* caller's responsibility to ensure that the UART is not sending or receiving
* data when this function is called.
*
* @param    InstancePtr is a pointer to the XUartNs550 instance to be worked on.
* @param    FormatPtr is a pointer to a format structure containing the data
*           format to be set.
*
* @return
*
* - XST_SUCCESS if the data format was successfully set.
* - XST_UART_BAUD_ERROR indicates the baud rate could not be set because
*   of the amount of error with the baud rate and the input clock frequency.
* - XST_INVALID_PARAM if one of the parameters was not valid.
*
* @note
*
* The data types in the format type, data bits and parity, are 32 bit fields
* to prevent a compiler warning that is a bug with the GNU PowerPC compiler.
* The asserts in this function will cause a warning if these fields are
* bytes.
* <br><br>
* The baud rates tested include: 1200, 2400, 4800, 9600, 19200, 38400, 57600
* and 115200.
*
*****************************************************************************/
XStatus XUartNs550_SetDataFormat(XUartNs550 *InstancePtr,
                                 XUartNs550Format *FormatPtr)
{
    XStatus Status;
    Xuint8 LcrRegister;

    XASSERT_NONVOID(InstancePtr != XNULL);
    XASSERT_NONVOID(FormatPtr != XNULL);

    /* Verify the inputs specified are valid and return an error if any
     * are not, without setting the data format
     */
    if ((FormatPtr->DataBits > XUN_FORMAT_8_BITS)       ||
        (FormatPtr->Parity > XUN_FORMAT_EVEN_PARITY)    ||

        ((FormatPtr->StopBits != XUN_FORMAT_2_STOP_BIT) &&
         (FormatPtr->StopBits != XUN_FORMAT_1_STOP_BIT)))
    {
        return XST_INVALID_PARAM;
    }

    /* Try to set the baud rate and if it's not successful then don't
     * continue altering the data format, this is done first to avoid the
     * format from being altered when an error occurs
     */
    Status = XUartNs550_SetBaudRate(InstancePtr, FormatPtr->BaudRate);
    if (Status != XST_SUCCESS)
    {
        return Status;
    }

    /* Read the line control register which contains the parity, length and
     * stop bits so they can be updated without affecting any other bits
     */
    LcrRegister = XIo_In8(InstancePtr->BaseAddress + XUN_LCR_OFFSET);

    /* Set the length of data (8,7,6,5) by first clearing out the bits
     * that control it in the register, then set the length in the register
     */
    LcrRegister &= ~XUN_LCR_LENGTH_MASK;
    LcrRegister |= FormatPtr->DataBits;

    /* Set the number of stop bits in the line control register, if the number
     * of stop bits is not 2, then it must be one which is the bit in the
     * register cleared
     */
    if (FormatPtr->StopBits == XUN_FORMAT_2_STOP_BIT)
    {
        LcrRegister |= XUN_LCR_2_STOP_BITS;
    }
    else
    {
        LcrRegister &= ~XUN_LCR_2_STOP_BITS;
    }

    /* Set the parity by first clearing out the bits that control it in the
     * register, then set the bits in the register, the default is no parity
     * after clearing the register bits
     */
    LcrRegister &= ~XUN_LCR_PARITY_MASK;
    if (FormatPtr->Parity != XUN_FORMAT_NO_PARITY)
    {
        /* Some form of parity is specified, set the bit indicating that
         * parity is enabled, then setup even or odd, the default is odd
         * after clearing the register bits
         */
        LcrRegister |= XUN_LCR_ENABLE_PARITY;
        if (FormatPtr->Parity == XUN_FORMAT_EVEN_PARITY)
        {
            LcrRegister |= XUN_LCR_EVEN_PARITY;
        }
    }

    /* Write the line control register out to save the new data format
     * that has been created
     */
    XIo_Out8(InstancePtr->BaseAddress + XUN_LCR_OFFSET, LcrRegister);

    return XST_SUCCESS;
}
/****************************************************************************/
/**
*
* Gets the data format for the specified UART. The data format includes the
* baud rate, number of data bits, number of stop bits, and parity.
*
* @param    InstancePtr is a pointer to the XUartNs550 instance to be worked on.
* @param    FormatPtr is a pointer to a format structure that will contain the
*           data format after this call completes.
*
* @return
*
* None.
*
* @note
*
* None.
*
* @internal
*
* This function gets the state of the hardware rather than returning a state
* that has been stored to ensure that the hardware is correct.
*
*****************************************************************************/
void XUartNs550_GetDataFormat(XUartNs550 *InstancePtr,
                              XUartNs550Format *FormatPtr)
{
    Xuint8 LcrRegister;

    XASSERT_VOID(InstancePtr != XNULL);
    XASSERT_VOID(FormatPtr != XNULL);

    /*
     * Assert validates the input arguments
     */
    XASSERT_VOID(InstancePtr != XNULL);
    XASSERT_VOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

    /* Get the baud rate from the instance, this is not retrieved from the
     * hardware because it is only kept as a divisor such that it is more
     * difficult to get back to the divisor
     */
    FormatPtr->BaudRate = InstancePtr->BaudRate;

    /* Read the line control register which contains the parity, length and
     * stop bits so they can be updated without affecting any other bits
     */
    LcrRegister = XIo_In8(InstancePtr->BaseAddress + XUN_LCR_OFFSET);

    /* Set the length of data (8,7,6,5) by first clearing out the bits
     * that control it in the register, then set the length in the register
     */
    FormatPtr->DataBits = LcrRegister & XUN_LCR_LENGTH_MASK;

    /* Set the number of stop bits by first clearing out the bits in that
     * control it in the register, then set the bits in the register, the
     * default is one stop bit after clearing the register bits
     */
    if (LcrRegister & XUN_LCR_2_STOP_BITS)
    {
        FormatPtr->StopBits = XUN_FORMAT_2_STOP_BIT;
    }
    else
    {
        FormatPtr->StopBits = XUN_FORMAT_1_STOP_BIT;
    }

    /* Determine what parity is set from the register and setup the format
     * to correspond
     */
    if ((LcrRegister & XUN_LCR_ENABLE_PARITY) == 0)
    {
        FormatPtr->Parity = XUN_FORMAT_NO_PARITY;
    }
    else
    {
        /* Parity is enables, so determine if it's even or odd and set the
         * format to correspond
         */
        if (LcrRegister & XUN_LCR_EVEN_PARITY)
        {
            FormatPtr->Parity = XUN_FORMAT_EVEN_PARITY;
        }
        else
        {
            FormatPtr->Parity = XUN_FORMAT_ODD_PARITY;
        }
    }
}