initialize-hardware.c

Go to the documentation of this file.

/*
 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).
 * Copyright (c) 2015-2025 Liviu Ionescu. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software
 * for any purpose is hereby granted, under the terms of the MIT license.
 *
 * If a copy of the license was not distributed with this file, it can
 * be obtained from https://opensource.org/licenses/mit.
 */
 
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wempty-translation-unit"
#endif
 
// ----------------------------------------------------------------------------
 
#if defined(__ARM_EABI__)
 
// ----------------------------------------------------------------------------
 
#if defined(OS_USE_OS_APP_CONFIG_H)
#include <cmsis-plus/os-app-config.h>
#endif
 
#include <cmsis-plus/rtos/os-hooks.h>
#include <cmsis_device.h>
 
// ----------------------------------------------------------------------------
 
#if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
extern unsigned int __vectors_start;
#endif
 
// ----------------------------------------------------------------------------
 
void __attribute__ ((weak))
os_startup_initialize_hardware_early (void)
{
  // Call the CSMSIS system initialisation routine.
  SystemInit ();
 
#if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
 
  // Set VTOR to the actual address, provided by the linker script.
  // Override the manual, possibly wrong, SystemInit() setting.
  SCB->VTOR = (uint32_t)(&__vectors_start);
  // Ensure all subsequence instructions use the new configuration.
  __DSB ();
 
#endif /* defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__) */
 
  // The current version of SystemInit() leaves the value of the clock
  // in a RAM variable (SystemCoreClock), which will be cleared shortly,
  // so it needs to be recomputed after the RAM initialisations
  // are completed.
 
#if defined(OS_INCLUDE_STARTUP_INIT_FP) || defined(__ARM_FP)
 
  // Normally FP init is done by SystemInit(). In case this is not done
  // there, it is possible to force its inclusion by defining
  // OS_INCLUDE_STARTUP_INIT_FP.
 
  // Enable the Cortex-M4 FPU only when -mfloat-abi=hard or -mfloat-abi=softfp.
  // Code taken from Section 7.1, Cortex-M4 TRM (DDI0439C)
 
  // Set bits 20-23 to enable CP10 and CP11 coprocessor.
  SCB->CPACR |= (0xF << 20);
 
  // Lazy save.
  FPU->FPCCR |= FPU_FPCCR_ASPEN_Msk | FPU_FPCCR_LSPEN_Msk;
 
#endif /* defined(OS_INCLUDE_STARTUP_INIT_FP) || defined (__ARM_FP) */
 
#if defined(OS_DEBUG_SEMIHOSTING_FAULTS)
 
  SCB->SHCSR |= SCB_SHCSR_USGFAULTENA_Msk;
 
#endif
}
 
// Temporarily disabled, to help identify missing application inits.
#if 0 || defined(__DOXYGEN__)
void __attribute__((weak))
os_startup_initialize_hardware (void)
{
  // Call the CSMSIS system clock routine to store the clock frequency
  // in the SystemCoreClock global RAM location.
  SystemCoreClockUpdate ();
}
#endif /* 0 || defined(__DOXYGEN__) */
 
// ----------------------------------------------------------------------------
 
#endif /* defined(__ARM_EABI__) */