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* Copyright (c) 2013-2014 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
* @brief Full C support initialization
*
*
* Initialization of full C support: zero the .bss, copy the .data if XIP,
* call _Cstart().
*
* Stack is available in this module, but not the global data/bss until their
* initialization is performed.
*/
#include <kernel.h>
#include <zephyr/types.h>
#include <toolchain.h>
#include <linker/linker-defs.h>
#include <kernel_internal.h>
#include <arch/arm/cortex_m/cmsis.h>
#include <string.h>
#ifdef CONFIG_CPU_CORTEX_M_HAS_VTOR
#ifdef CONFIG_XIP
#define VECTOR_ADDRESS ((uintptr_t)_vector_start)
#else
#define VECTOR_ADDRESS CONFIG_SRAM_BASE_ADDRESS
#endif
static inline void relocate_vector_table(void)
{
SCB->VTOR = VECTOR_ADDRESS & SCB_VTOR_TBLOFF_Msk;
__DSB();
__ISB();
}
#else
#if defined(CONFIG_SW_VECTOR_RELAY)
_GENERIC_SECTION(.vt_pointer_section) void *_vector_table_pointer;
#endif
#define VECTOR_ADDRESS 0
void __weak relocate_vector_table(void)
{
#if defined(CONFIG_XIP) && (CONFIG_FLASH_BASE_ADDRESS != 0) || \
!defined(CONFIG_XIP) && (CONFIG_SRAM_BASE_ADDRESS != 0)
size_t vector_size = (size_t)_vector_end - (size_t)_vector_start;
memcpy(VECTOR_ADDRESS, _vector_start, vector_size);
#elif defined(CONFIG_SW_VECTOR_RELAY)
_vector_table_pointer = _vector_start;
#endif
}
#endif /* CONFIG_CPU_CORTEX_M_HAS_VTOR */
#ifdef CONFIG_FLOAT
static inline void enable_floating_point(void)
{
/*
* Upon reset, the Co-Processor Access Control Register is 0x00000000.
* Enable CP10 and CP11 coprocessors to enable floating point.
*/
SCB->CPACR |= CPACR_CP10_FULL_ACCESS | CPACR_CP11_FULL_ACCESS;
/*
* Upon reset, the FPU Context Control Register is 0xC0000000
* (both Automatic and Lazy state preservation is enabled).
* Disable lazy state preservation so the volatile FP registers are
* always saved on exception.
*/
FPU->FPCCR = FPU_FPCCR_ASPEN_Msk; /* FPU_FPCCR_LSPEN = 0 */
/*
* Although automatic state preservation is enabled, the processor
* does not automatically save the volatile FP registers until they
* have first been touched. Perform a dummy move operation so that
* the stack frames are created as expected before any thread
* context switching can occur. It has to be surrounded by instruction
* synchronisation barriers to ensure that the whole sequence is
* serialized.
*/
__asm__ volatile(
"isb;\n\t"
"vmov s0, s0;\n\t"
"isb;\n\t"
);
}
#else
static inline void enable_floating_point(void)
{
}
#endif
extern FUNC_NORETURN void _Cstart(void);
/**
*
* @brief Prepare to and run C code
*
* This routine prepares for the execution of and runs C code.
*
* @return N/A
*/
#ifdef CONFIG_BOOT_TIME_MEASUREMENT
extern u64_t __start_time_stamp;
#endif
void _PrepC(void)
{
relocate_vector_table();
enable_floating_point();
_bss_zero();
_data_copy();
#ifdef CONFIG_BOOT_TIME_MEASUREMENT
__start_time_stamp = 0;
#endif
_Cstart();
CODE_UNREACHABLE;
}
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