mpu.c
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/*
* Copyright (C) 2016 Loci Controls Inc.
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_cortexm_common
* @{
*
* @file mpu.c
* @brief Cortex-M Memory Protection Unit (MPU) Driver
*
* @author Ian Martin <ian@locicontrols.com>
*
* @}
*/
#include <assert.h>
#include "cpu.h"
#include "mpu.h"
int mpu_disable(void) {
#if __MPU_PRESENT
MPU->CTRL &= ~MPU_CTRL_ENABLE_Msk;
return 0;
#else
return -1;
#endif
}
int mpu_enable(void) {
#if __MPU_PRESENT
MPU->CTRL |= MPU_CTRL_PRIVDEFENA_Msk | MPU_CTRL_ENABLE_Msk;
/* Enable the memory fault exception */
SCB->SHCSR |= SCB_SHCSR_MEMFAULTENA_Msk;
return 0;
#else
return -1;
#endif
}
bool mpu_enabled(void) {
#if __MPU_PRESENT
return (MPU->CTRL & MPU_CTRL_ENABLE_Msk) != 0;
#else
return false;
#endif
}
int mpu_configure(uint_fast8_t region, uintptr_t base, uint_fast32_t attr) {
#if __MPU_PRESENT
assert(region < MPU_NUM_REGIONS);
MPU->RNR = region;
MPU->RBAR = base & MPU_RBAR_ADDR_Msk;
MPU->RASR = attr | MPU_RASR_ENABLE_Msk;
if (!mpu_enabled()) {
mpu_enable();
}
return 0;
#else
return -1;
#endif
}