//*****************************************************************************
//
// can.c - Driver for the CAN module.
//
// Copyright (c) 2006-2008 Luminary Micro, Inc.  All rights reserved.
// 
// Software License Agreement
// 
// Luminary Micro, Inc. (LMI) is supplying this software for use solely and
// exclusively on LMI's microcontroller products.
// 
// The software is owned by LMI and/or its suppliers, and is protected under
// applicable copyright laws.  All rights are reserved.  You may not combine
// this software with "viral" open-source software in order to form a larger
// program.  Any use in violation of the foregoing restrictions may subject
// the user to criminal sanctions under applicable laws, as well as to civil
// liability for the breach of the terms and conditions of this license.
// 
// THIS SOFTWARE IS PROVIDED "AS IS".  NO WARRANTIES, WHETHER EXPRESS, IMPLIED
// OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
// LMI SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR
// CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
// 
// This is part of revision 2752 of the Stellaris Peripheral Driver Library.
//
//*****************************************************************************

//*****************************************************************************
//
//! \addtogroup can_api
//! @{
//
//*****************************************************************************
#include "../hw_ints.h"
#include "../hw_memmap.h"
#include "../hw_types.h"
#include "../hw_nvic.h"
#include "../hw_can.h"
#include "debug.h"
#include "interrupt.h"
#include "sysctl.h"
#include "can.h"

//*****************************************************************************
//
// This is the maximum number that can be stored as an 11bit Message
// identifier.
//
//*****************************************************************************
#define CAN_MAX_11BIT_MSG_ID    (0x7ff)

//*****************************************************************************
//
// This is used as the loop delay for accessing the CAN controller registers.
//
//*****************************************************************************
#define CAN_RW_DELAY            (5)

//*****************************************************************************
//
//! \internal
//!
//! Returns the CAN controller interrupt number.
//!
//! \param ulBase is the base address of the selected CAN controller
//!
//! Given a CAN controller base address, returns the corresponding interrupt
//! number.
//!
//! This function replaces the original CANGetIntNumber() API and performs the
//! same actions.  A macro is provided in <tt>can.h</tt> to map the original
//! API to this API.
//!
//! \return Returns a CAN interrupt number, or -1 if \e ulPort is invalid.
//
//*****************************************************************************
static long
CANIntNumberGet(unsigned long ulBase)
{
    long lIntNumber;

    //
    // Return the interrupt number for the given CAN controller.
    //
    switch(ulBase)
    {
        //
        // Return the interrupt number for CAN 0
        //
        case CAN0_BASE:
        {
            lIntNumber = INT_CAN0;
            break;
        }

        //
        // Return the interrupt number for CAN 1
        //
        case CAN1_BASE:
        {
            lIntNumber = INT_CAN1;
            break;
        }

        //
        // Return the interrupt number for CAN 2
        //
        case CAN2_BASE:
        {
            lIntNumber = INT_CAN2;
            break;
        }

        //
        // Return -1 to indicate a bad address was passed in.
        //
        default:
        {
            lIntNumber = -1;
        }
    }
    return(lIntNumber);
}

//*****************************************************************************
//
//! \internal
//!
//! Reads a CAN controller register.
//!
//! \param ulRegAddress is the full address of the CAN register to be read.
//!
//! This function performs the necessary synchronization to read from a CAN
//! controller register.
//!
//! This function replaces the original CANReadReg() API and performs the same
//! actions.  A macro is provided in <tt>can.h</tt> to map the original API to
//! this API.
//!
//! \note This function provides the delay required to access CAN registers.
//! This delay is required when accessing CAN registers directly.
//!
//! \return Returns the value read from the register.
//
//*****************************************************************************
static unsigned long
CANRegRead(unsigned long ulRegAddress)
{
    volatile int iDelay;
    unsigned long ulRetVal;
    unsigned long ulIntNumber;
    unsigned long ulReenableInts;

    //
    // Get the CAN interrupt number from the register base address.
    //
    ulIntNumber = CANIntNumberGet(ulRegAddress & 0xfffff000);

    //
    // Make sure that the CAN base address was valid.
    //
    ASSERT(ulIntNumber != (unsigned long)-1);

    //
    // Remember current state so that CAN interrupts are only re-enabled if
    // they were already enabled.
    //
    ulReenableInts = HWREG(NVIC_EN1) & (1 << (ulIntNumber - 48));

    //
    // If the CAN interrupt was enabled then disable it.
    //
    if(ulReenableInts)
    {
        IntDisable(ulIntNumber);
    }

    //
    // Trigger the inital read to the CAN controller.  The value returned at
    // this point is not valid.
    //
    HWREG(ulRegAddress);

    //
    // This delay is necessary for the CAN have the correct data on the bus.
    //
    for(iDelay = 0; iDelay < CAN_RW_DELAY; iDelay++)
    {
    }

    //
    // Do the final read that has the valid value of the register.
    //
    ulRetVal = HWREG(ulRegAddress);

    //
    // Reenable CAN interrupts if they were enabled before this call.
    //
    if(ulReenableInts)
    {
        IntEnable(ulIntNumber);
    }

    return(ulRetVal);
}

//*****************************************************************************
//
//! \internal
//!
//! Writes a CAN controller register.
//!
//! \param ulRegAddress is the full address of the CAN register to be written.
//! \param ulRegValue is the value to write into the register specified by
//! \e ulRegAddress.
//!
//! This function takes care of the synchronization necessary to write to a
//! CAN controller register.
//!
//! This function replaces the original CANWriteReg() API and performs the same
//! actions.  A macro is provided in <tt>can.h</tt> to map the original API to
//! this API.
//!
//! \note The delays in this function are required when accessing CAN registers
//! directly.
//!
//! \return None.
//
//*****************************************************************************
static void
CANRegWrite(unsigned long ulRegAddress, unsigned long ulRegValue)
{
    volatile int iDelay;

    //
    // Trigger the inital write to the CAN controller.  The value will not make
    // it out to the CAN controller for CAN_RW_DELAY cycles.
    //
    HWREG(ulRegAddress) = ulRegValue;

    //
    // Delay to allow the CAN controller to receive the new data.
    //
    for(iDelay = 0; iDelay < CAN_RW_DELAY; iDelay++)
    {
    }
}

//*****************************************************************************
//
//! \internal
//!
//! Copies data from a buffer to the CAN Data registers.
//!
//! \param pucData is a pointer to the data to be written out to the CAN
//! controller's data registers.
//! \param pulRegister is an unsigned long pointer to the first register of the
//! CAN controller's data registers.  For example, in order to use the IF1
//! register set on CAN controller 0, the value would be: \b CAN0_BASE \b +
//! \b CAN_O_IF1DA1.
//! \param iSize is the number of bytes to copy into the CAN controller.
//!
//! This function takes the steps necessary to copy data from a contiguous
//! buffer in memory into the non-contiguous data registers used by the CAN
//! controller.  This function is rarely used outside of the CANMessageSet()
//! function.
//!
//! This function replaces the original CANWriteDataReg() API and performs the
//! same actions.  A macro is provided in <tt>can.h</tt> to map the original
//! API to this API.
//!
//! \return None.
//
//*****************************************************************************
static void
CANDataRegWrite(unsigned char *pucData, unsigned long *pulRegister, int iSize)
{
    int iIdx;
    unsigned long ulValue;

    //
    // Loop always copies 1 or 2 bytes per iteration.
    //
    for(iIdx = 0; iIdx < iSize; )
    {

        //
        // Write out the data 16 bits at a time since this is how the registers
        // are aligned in memory.
        //
        ulValue = pucData[iIdx++];

        //
        // Only write the second byte if needed otherwise it will be zero.
        //
        if(iIdx < iSize)
        {
            ulValue |= (pucData[iIdx++] << 8);
        }
        CANRegWrite((unsigned long)(pulRegister++), ulValue);
    }
}

//*****************************************************************************
//
//! \internal
//!
//! Copies data from a buffer to the CAN Data registers.
//!
//! \param pucData is a pointer to the location to store the data read from the
//! CAN controller's data registers.
//! \param pulRegister is an unsigned long pointer to the first register of the
//! CAN controller's data registers.  For example, in order to use the IF1
//! register set on CAN controller 1, the value would be: \b CAN0_BASE \b +
//! \b CAN_O_IF1DA1.
//! \param iSize is the number of bytes to copy from the CAN controller.
//!
//! This function takes the steps necessary to copy data to a contiguous buffer
//! in memory from the non-contiguous data registers used by the CAN
//! controller.  This function is rarely used outside of the CANMessageGet()
//! function.
//!
//! This function replaces the original CANReadDataReg() API and performs the
//! same actions.  A macro is provided in <tt>can.h</tt> to map the original
//! API to this API.
//!
//! \return None.
//
//*****************************************************************************
static void
CANDataRegRead(unsigned char *pucData, unsigned long *pulRegister, int iSize)
{
    int iIdx;
    unsigned long ulValue;

    //
    // Loop always copies 1 or 2 bytes per iteration.
    //
    for(iIdx = 0; iIdx < iSize; )
    {
        //
        // Read out the data 16 bits at a time since this is how the registers
        // are aligned in memory.
        //
        ulValue = CANRegRead((unsigned long)(pulRegister++));

        //
        // Store the first byte.
        //
        pucData[iIdx++] = (unsigned char)ulValue;

        //
        // Only read the second byte if needed.
        //
        if(iIdx < iSize)
        {
            pucData[iIdx++] = (unsigned char)(ulValue >> 8);
        }
    }
}

//*****************************************************************************
//
//! Initializes the CAN controller after reset.
//!
//! \param ulBase is the base address of the CAN controller.
//!
//! After reset, the CAN controller is left in the disabled state.  However,
//! the memory used for message objects contains undefined values and must be
//! cleared prior to enabling the CAN controller the first time.  This prevents
//! unwanted transmission or reception of data before the message objects are
//! configured.  This function must be called before enabling the controller
//! the first time.
//!
//! \return None.
//
//*****************************************************************************
void
CANInit(unsigned long ulBase)
{
    int iMsg;

    //
    // Make sure that the address passed in is valid.
    //
    ASSERT((ulBase == CAN0_BASE) ||
           (ulBase == CAN1_BASE) ||
           (ulBase == CAN2_BASE));

    //
    // Place CAN controller in init state, regardless of previous state.  This
    // will put controller in idle, and allow the message object RAM to be
    // programmed.
    //
    CANRegWrite(ulBase + CAN_O_CTL, CAN_CTL_INIT);