interrupt.c

//*****************************************************************************
//
// interrupt.c - Driver for the NVIC Interrupt Controller.
//
// Copyright (c) 2005-2009 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 4694 of the Stellaris Peripheral Driver Library.
//
//*****************************************************************************

//*****************************************************************************
//
//! \addtogroup interrupt_api
//! @{
//
//*****************************************************************************

#include "inc/hw_ints.h"
#include "inc/hw_nvic.h"
#include "inc/hw_types.h"
#include "driverlib/cpu.h"
#include "driverlib/debug.h"
#include "driverlib/interrupt.h"

//*****************************************************************************
//
// This is a mapping between priority grouping encodings and the number of
// preemption priority bits.
//
//*****************************************************************************
static const unsigned long g_pulPriority[] =
{
    NVIC_APINT_PRIGROUP_0_8, NVIC_APINT_PRIGROUP_1_7, NVIC_APINT_PRIGROUP_2_6,
    NVIC_APINT_PRIGROUP_3_5, NVIC_APINT_PRIGROUP_4_4, NVIC_APINT_PRIGROUP_5_3,
    NVIC_APINT_PRIGROUP_6_2, NVIC_APINT_PRIGROUP_7_1
};

//*****************************************************************************
//
// This is a mapping between interrupt number and the register that contains
// the priority encoding for that interrupt.
//
//*****************************************************************************
static const unsigned long g_pulRegs[] =
{
    0, NVIC_SYS_PRI1, NVIC_SYS_PRI2, NVIC_SYS_PRI3, NVIC_PRI0, NVIC_PRI1,
    NVIC_PRI2, NVIC_PRI3, NVIC_PRI4, NVIC_PRI5, NVIC_PRI6, NVIC_PRI7,
    NVIC_PRI8, NVIC_PRI9, NVIC_PRI10, NVIC_PRI11, NVIC_PRI12, NVIC_PRI13
};

//*****************************************************************************
//
//! \internal
//! The default interrupt handler.
//!
//! This is the default interrupt handler for all interrupts.  It simply loops
//! forever so that the system state is preserved for observation by a
//! debugger.  Since interrupts should be disabled before unregistering the
//! corresponding handler, this should never be called.
//!
//! \return None.
//
//*****************************************************************************
static void
IntDefaultHandler(void)
{
    //
    // Go into an infinite loop.
    //
    while(1)
    {
    }
}

//*****************************************************************************
//
// The processor vector table.
//
// This contains a list of the handlers for the various interrupt sources in
// the system.  The layout of this list is defined by the hardware; assertion
// of an interrupt causes the processor to start executing directly at the
// address given in the corresponding location in this list.
//
//*****************************************************************************
#if defined(ewarm)
static __no_init void (*g_pfnRAMVectors[NUM_INTERRUPTS])(void) @ "VTABLE";
#elif defined(sourcerygxx)
static __attribute__((section(".cs3.region-head.ram")))
void (*g_pfnRAMVectors[NUM_INTERRUPTS])(void);
#else
static __attribute__((section("vtable")))
void (*g_pfnRAMVectors[NUM_INTERRUPTS])(void);
#endif

//*****************************************************************************
//
//! Enables the processor interrupt.
//!
//! Allows the processor to respond to interrupts.  This does not affect the
//! set of interrupts enabled in the interrupt controller; it just gates the
//! single interrupt from the controller to the processor.
//!
//! \note Previously, this function had no return value.  As such, it was
//! possible to include <tt>interrupt.h</tt> and call this function without
//! having included <tt>hw_types.h</tt>.  Now that the return is a
//! <tt>tBoolean</tt>, a compiler error will occur in this case.  The solution
//! is to include <tt>hw_types.h</tt> before including <tt>interrupt.h</tt>.
//!
//! \return Returns \b true if interrupts were disabled when the function was
//! called or \b false if they were initially enabled.
//
//*****************************************************************************
tBoolean
IntMasterEnable(void)
{
    //
    // Enable processor interrupts.
    //
    return(CPUcpsie());
}

//*****************************************************************************
//
//! Disables the processor interrupt.
//!
//! Prevents the processor from receiving interrupts.  This does not affect the
//! set of interrupts enabled in the interrupt controller; it just gates the
//! single interrupt from the controller to the processor.
//!
//! \note Previously, this function had no return value.  As such, it was
//! possible to include <tt>interrupt.h</tt> and call this function without
//! having included <tt>hw_types.h</tt>.  Now that the return is a
//! <tt>tBoolean</tt>, a compiler error will occur in this case.  The solution
//! is to include <tt>hw_types.h</tt> before including <tt>interrupt.h</tt>.
//!
//! \return Returns \b true if interrupts were already disabled when the
//! function was called or \b false if they were initially enabled.
//
//*****************************************************************************
tBoolean
IntMasterDisable(void)
{
    //
    // Disable processor interrupts.
    //
    return(CPUcpsid());
}

//*****************************************************************************
//
//! Registers a function to be called when an interrupt occurs.
//!
//! \param ulInterrupt specifies the interrupt in question.
//! \param pfnHandler is a pointer to the function to be called.
//!
//! This function is used to specify the handler function to be called when the
//! given interrupt is asserted to the processor.  When the interrupt occurs,
//! if it is enabled (via IntEnable()), the handler function will be called in
//! interrupt context.  Since the handler function can preempt other code, care
//! must be taken to protect memory or peripherals that are accessed by the
//! handler and other non-handler code.
//!
//! \note The use of this function (directly or indirectly via a peripheral
//! driver interrupt register function) moves the interrupt vector table from
//! flash to SRAM.  Therefore, care must be taken when linking the application
//! to ensure that the SRAM vector table is located at the beginning of SRAM;
//! otherwise NVIC will not look in the correct portion of memory for the
//! vector table (it requires the vector table be on a 1 kB memory alignment).
//! Normally, the SRAM vector table is so placed via the use of linker scripts;
//! some tool chains, such as the evaluation version of RV-MDK, do not support
//! linker scripts and therefore will not produce a valid executable.  See the
//! discussion of compile-time versus run-time interrupt handler registration
//! in the introduction to this chapter.
//!
//! \return None.
//
//*****************************************************************************
void
IntRegister(unsigned long ulInterrupt, void (*pfnHandler)(void))
{
    unsigned long ulIdx, ulValue;

    //
    // Check the arguments.
    //
    ASSERT(ulInterrupt < NUM_INTERRUPTS);

    //
    // Make sure that the RAM vector table is correctly aligned.
    //
    ASSERT(((unsigned long)g_pfnRAMVectors & 0x000003ff) == 0);

    //
    // See if the RAM vector table has been initialized.
    //
    if(HWREG(NVIC_VTABLE) != (unsigned long)g_pfnRAMVectors)
    {
        //
        // Copy the vector table from the beginning of FLASH to the RAM vector
        // table.
        //
        ulValue = HWREG(NVIC_VTABLE);
        for(ulIdx = 0; ulIdx < NUM_INTERRUPTS; ulIdx++)
        {
            g_pfnRAMVectors[ulIdx] = (void (*)(void))HWREG((ulIdx * 4) +
                                                     ulValue);
        }

        //
        // Point NVIC at the RAM vector table.
        //
        HWREG(NVIC_VTABLE) = (unsigned long)g_pfnRAMVectors;
    }

    //
    // Save the interrupt handler.
    //
    g_pfnRAMVectors[ulInterrupt] = pfnHandler;
}

//*****************************************************************************
//
//! Unregisters the function to be called when an interrupt occurs.
//!
//! \param ulInterrupt specifies the interrupt in question.
//!
//! This function is used to indicate that no handler should be called when the
//! given interrupt is asserted to the processor.  The interrupt source will be
//! automatically disabled (via IntDisable()) if necessary.
//!
//! \sa IntRegister() for important information about registering interrupt
//! handlers.
//!
//! \return None.
//
//*****************************************************************************
void
IntUnregister(unsigned long ulInterrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ulInterrupt < NUM_INTERRUPTS);

    //
    // Reset the interrupt handler.
    //
    g_pfnRAMVectors[ulInterrupt] = IntDefaultHandler;
}

//*****************************************************************************
//
//! Sets the priority grouping of the interrupt controller.
//!
//! \param ulBits specifies the number of bits of preemptable priority.
//!
//! This function specifies the split between preemptable priority levels and
//! subpriority levels in the interrupt priority specification.  The range of
//! the grouping values are dependent upon the hardware implementation; on
//! the Stellaris family, three bits are available for hardware interrupt
//! prioritization and therefore priority grouping values of three through
//! seven have the same effect.
//!
//! \return None.
//
//*****************************************************************************
void
IntPriorityGroupingSet(unsigned long ulBits)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBits < NUM_PRIORITY);

    //
    // Set the priority grouping.
    //
    HWREG(NVIC_APINT) = NVIC_APINT_VECTKEY | g_pulPriority[ulBits];
}

//*****************************************************************************
//
//! Gets the priority grouping of the interrupt controller.
//!
//! This function returns the split between preemptable priority levels and
//! subpriority levels in the interrupt priority specification.
//!
//! \return The number of bits of preemptable priority.
//
//*****************************************************************************
unsigned long
IntPriorityGroupingGet(void)
{
    unsigned long ulLoop, ulValue;

    //
    // Read the priority grouping.
    //
    ulValue = HWREG(NVIC_APINT) & NVIC_APINT_PRIGROUP_M;

    //
    // Loop through the priority grouping values.
    //
    for(ulLoop = 0; ulLoop < NUM_PRIORITY; ulLoop++)
    {
        //
        // Stop looping if this value matches.
        //
        if(ulValue == g_pulPriority[ulLoop])
        {
            break;
        }
    }

    //
    // Return the number of priority bits.
    //
    return(ulLoop);
}

//*****************************************************************************
//
//! Sets the priority of an interrupt.
//!
//! \param ulInterrupt specifies the interrupt in question.
//! \param ucPriority specifies the priority of the interrupt.
//!
//! This function is used to set the priority of an interrupt.  When multiple
//! interrupts are asserted simultaneously, the ones with the highest priority
//! are processed before the lower priority interrupts.  Smaller numbers
//! correspond to higher interrupt priorities; priority 0 is the highest
//! interrupt priority.
//!
//! The hardware priority mechanism will only look at the upper N bits of the
//! priority level (where N is 3 for the Stellaris family), so any
//! prioritization must be performed in those bits.  The remaining bits can be
//! used to sub-prioritize the interrupt sources, and may be used by the
//! hardware priority mechanism on a future part.  This arrangement allows
//! priorities to migrate to different NVIC implementations without changing
//! the gross prioritization of the interrupts.
//!
//! \return None.
//
//*****************************************************************************
void
IntPrioritySet(unsigned long ulInterrupt, unsigned char ucPriority)
{
    unsigned long ulTemp;

    //
    // Check the arguments.
    //
    ASSERT((ulInterrupt >= 4) && (ulInterrupt < NUM_INTERRUPTS));

    //
    // Set the interrupt priority.
    //
    ulTemp = HWREG(g_pulRegs[ulInterrupt >> 2]);
    ulTemp &= ~(0xFF << (8 * (ulInterrupt & 3)));
    ulTemp |= ucPriority << (8 * (ulInterrupt & 3));
    HWREG(g_pulRegs[ulInterrupt >> 2]) = ulTemp;
}

//*****************************************************************************
//
//! Gets the priority of an interrupt.
//!
//! \param ulInterrupt specifies the interrupt in question.
//!
//! This function gets the priority of an interrupt.  See IntPrioritySet() for
//! a definition of the priority value.
//!
//! \return Returns the interrupt priority, or -1 if an invalid interrupt was
//! specified.
//
//*****************************************************************************
long
IntPriorityGet(unsigned long ulInterrupt)
{
    //
    // Check the arguments.
    //
    ASSERT((ulInterrupt >= 4) && (ulInterrupt < NUM_INTERRUPTS));

    //
    // Return the interrupt priority.
    //
    return((HWREG(g_pulRegs[ulInterrupt >> 2]) >> (8 * (ulInterrupt & 3))) &
           0xFF);
}

//*****************************************************************************
//
//! Enables an interrupt.
//!
//! \param ulInterrupt specifies the interrupt to be enabled.
//!
//! The specified interrupt is enabled in the interrupt controller.  Other
//! enables for the interrupt (such as at the peripheral level) are unaffected
//! by this function.
//!
//! \return None.
//
//*****************************************************************************
void
IntEnable(unsigned long ulInterrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ulInterrupt < NUM_INTERRUPTS);

    //
    // Determine the interrupt to enable.
    //
    if(ulInterrupt == FAULT_MPU)
    {
        //
        // Enable the MemManage interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) |= NVIC_SYS_HND_CTRL_MEM;
    }
    else if(ulInterrupt == FAULT_BUS)
    {
        //
        // Enable the bus fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) |= NVIC_SYS_HND_CTRL_BUS;
    }
    else if(ulInterrupt == FAULT_USAGE)
    {
        //
        // Enable the usage fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) |= NVIC_SYS_HND_CTRL_USAGE;
    }
    else if(ulInterrupt == FAULT_SYSTICK)
    {
        //
        // Enable the System Tick interrupt.
        //
        HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN;
    }
    else if((ulInterrupt >= 16) && (ulInterrupt <= 47))
    {
        //
        // Enable the general interrupt.
        //
        HWREG(NVIC_EN0) = 1 << (ulInterrupt - 16);
    }
    else if(ulInterrupt >= 48)
    {
        //
        // Enable the general interrupt.
        //
        HWREG(NVIC_EN1) = 1 << (ulInterrupt - 48);
    }
}

//*****************************************************************************
//
//! Disables an interrupt.
//!
//! \param ulInterrupt specifies the interrupt to be disabled.
//!
//! The specified interrupt is disabled in the interrupt controller.  Other
//! enables for the interrupt (such as at the peripheral level) are unaffected
//! by this function.
//!
//! \return None.
//
//*****************************************************************************
void
IntDisable(unsigned long ulInterrupt)
{
    //
    // Check the arguments.
    //
    ASSERT(ulInterrupt < NUM_INTERRUPTS);

    //
    // Determine the interrupt to disable.
    //
    if(ulInterrupt == FAULT_MPU)
    {
        //
        // Disable the MemManage interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) &= ~(NVIC_SYS_HND_CTRL_MEM);
    }
    else if(ulInterrupt == FAULT_BUS)
    {
        //
        // Disable the bus fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) &= ~(NVIC_SYS_HND_CTRL_BUS);
    }
    else if(ulInterrupt == FAULT_USAGE)
    {
        //
        // Disable the usage fault interrupt.
        //
        HWREG(NVIC_SYS_HND_CTRL) &= ~(NVIC_SYS_HND_CTRL_USAGE);
    }
    else if(ulInterrupt == FAULT_SYSTICK)
    {
        //
        // Disable the System Tick interrupt.
        //
        HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN);
    }
    else if((ulInterrupt >= 16) && (ulInterrupt <= 47))
    {
        //
        // Disable the general interrupt.
        //
        HWREG(NVIC_DIS0) = 1 << (ulInterrupt - 16);
    }
    else if(ulInterrupt >= 48)
    {
        //
        // Disable the general interrupt.
        //
        HWREG(NVIC_DIS1) = 1 << (ulInterrupt - 48);
    }
}

//*****************************************************************************
//
// Close the Doxygen group.
//! @}
//
//*****************************************************************************