mpu.c

基于TI公司Cortex-M3的uart超级通信开发

//*****************************************************************************
//
// mpu.c - Driver for the Cortex-M3 memory protection unit (MPU).
//
// Copyright (c) 2007-2009 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 5228 of the Stellaris Peripheral Driver Library.
//
//*****************************************************************************

//*****************************************************************************
//
//! \addtogroup mpu_api
//! @{
//
//*****************************************************************************

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

//*****************************************************************************
//
//! Enables and configures the MPU for use.
//!
//! \param ulMPUConfig is the logical OR of the possible configurations.
//!
//! This function enables the Cortex-M3 memory protection unit.  It also
//! configures the default behavior when in privileged mode and while
//! handling a hard fault or NMI.  Prior to enabling the MPU, at least one
//! region must be set by calling MPURegionSet() or else by enabling the
//! default region for privileged mode by passing the
//! \b MPU_CONFIG_PRIV_DEFAULT flag to MPUEnable().
//! Once the MPU is enabled, a memory management fault will be generated
//! for any memory access violations.
//!
//! The \e ulMPUConfig parameter should be the logical OR of any of the
//! following:
//!
//! - \b MPU_CONFIG_PRIV_DEFAULT enables the default memory map when in
//! privileged mode and when no other regions are defined.  If this option
//! is not enabled, then there must be at least one valid region already
//! defined when the MPU is enabled.
//! - \b MPU_CONFIG_HARDFLT_NMI enables the MPU while in a hard fault or NMI
//! exception handler.  If this option is not enabled, then the MPU is
//! disabled while in one of these exception handlers and the default
//! memory map is applied.
//! - \b MPU_CONFIG_NONE chooses none of the above options.  In this case,
//! no default memory map is provided in privileged mode, and the MPU will
//! not be enabled in the fault handlers.
//!
//! \return None.
//
//*****************************************************************************
void
MPUEnable(unsigned long ulMPUConfig)
{
    //
    // Check the arguments.
    //
    ASSERT(!(ulMPUConfig & ~(MPU_CONFIG_PRIV_DEFAULT |
                             MPU_CONFIG_HARDFLT_NMI)));

    //
    // Set the MPU control bits according to the flags passed by the user,
    // and also set the enable bit.
    //
    HWREG(NVIC_MPU_CTRL) = ulMPUConfig | NVIC_MPU_CTRL_ENABLE;
}

//*****************************************************************************
//
//! Disables the MPU for use.
//!
//! This function disables the Cortex-M3 memory protection unit.  When the
//! MPU is disabled, the default memory map is used and memory management
//! faults are not generated.
//!
//! \return None.
//
//*****************************************************************************
void
MPUDisable(void)
{
    //
    // Turn off the MPU enable bit.
    //
    HWREG(NVIC_MPU_CTRL) &= ~NVIC_MPU_CTRL_ENABLE;
}

//*****************************************************************************
//
//! Gets the count of regions supported by the MPU.
//!
//! This function is used to get the number of regions that are supported by
//! the MPU.  This is the total number that are supported, including regions
//! that are already programmed.
//!
//! \return The number of memory protection regions that are available
//! for programming using MPURegionSet().
//
//*****************************************************************************
unsigned long
MPURegionCountGet(void)
{
    //
    // Read the DREGION field of the MPU type register, and mask off
    // the bits of interest to get the count of regions.
    //
    return((HWREG(NVIC_MPU_TYPE) & NVIC_MPU_TYPE_DREGION_M)
            >> NVIC_MPU_TYPE_DREGION_S);
}

//*****************************************************************************
//
//! Enables a specific region.
//!
//! \param ulRegion is the region number to enable.
//!
//! This function is used to enable a memory protection region.  The region
//! should already be set up with the MPURegionSet() function.  Once enabled,
//! the memory protection rules of the region will be applied and access
//! violations will cause a memory management fault.
//!
//! \return None.
//
//*****************************************************************************
void
MPURegionEnable(unsigned long ulRegion)
{
    //
    // Check the arguments.
    //
    ASSERT(ulRegion < 8);

    //
    // Select the region to modify.
    //
    HWREG(NVIC_MPU_NUMBER) = ulRegion;

    //
    // Modify the enable bit in the region attributes.
    //
    HWREG(NVIC_MPU_ATTR) |= NVIC_MPU_ATTR_ENABLE;
}

//*****************************************************************************
//
//! Disables a specific region.
//!
//! \param ulRegion is the region number to disable.
//!
//! This function is used to disable a previously enabled memory protection
//! region.  The region will remain configured if it is not overwritten with
//! another call to MPURegionSet(), and can be enabled again by calling
//! MPURegionEnable().
//!
//! \return None.
//
//*****************************************************************************
void
MPURegionDisable(unsigned long ulRegion)
{
    //
    // Check the arguments.
    //
    ASSERT(ulRegion < 8);

    //
    // Select the region to modify.
    //
    HWREG(NVIC_MPU_NUMBER) = ulRegion;

    //
    // Modify the enable bit in the region attributes.
    //
    HWREG(NVIC_MPU_ATTR) &= ~NVIC_MPU_ATTR_ENABLE;
}

//*****************************************************************************
//
//! Sets up the access rules for a specific region.
//!
//! \param ulRegion is the region number to set up.
//! \param ulAddr is the base address of the region.  It must be aligned
//! according to the size of the region specified in ulFlags.
//! \param ulFlags is a set of flags to define the attributes of the region.
//!
//! This function sets up the protection rules for a region.  The region has
//! a base address and a set of attributes including the size, which must
//! be a power of 2.  The base address parameter, \e ulAddr, must be aligned
//! according to the size.
//!
//! The \e ulFlags parameter is the logical OR of all of the attributes
//! of the region.  It is a combination of choices for region size,
//! execute permission, read/write permissions, disabled sub-regions,
//! and a flag to determine if the region is enabled.
//!
//! The size flag determines the size of a region, and must be one of the
//! following:
//!
//! - \b MPU_RGN_SIZE_32B
//! - \b MPU_RGN_SIZE_64B
//! - \b MPU_RGN_SIZE_128B
//! - \b MPU_RGN_SIZE_256B