mirror of https://github.com/ARMmbed/mbed-os.git
121 lines
4.0 KiB
C
121 lines
4.0 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2006-2016 ARM Limited
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* mbed OS boot sequence
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*
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* Most of mbed supported targets use default ARM Cortex M boot approach, where the core starts executing reset vector
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* after power up. Reset ISR is defined for each target by the vendor (basing on CMSIS template). Reset vector is
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* responsible for low level platform init and then calling in libc (__main). Depending on compiler and version of C
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* library, predefined function will be called which is implemented by mbed OS.
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*
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* There's number of functions, vendor and users can provide to setup the platform and/or inject a code to be executed
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* before main():
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* * Reset vector and SystemInit: Reset vector should do low level core and board initialization.
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* * mbed_sdk_init: Higher level board init and making sure the board is ready for the mbed OS.
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* * mbed_main: User's code to be executed before main().
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* * main: Standard application code.
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*
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* Other notes:
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*
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* * In addition to the above, libc will use functions defined in mbed_boot.c: __rtos_malloc_lock/unlock,
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* __rtos_env_lock/unlock.
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*
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* * First step after the execution is passed to mbed, software_init_hook for GCC and __rt_entry for ARMC is to
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* initialize heap.
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*
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* Memory layout notes:
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* ====================
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*
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* IAR Memory layout :
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* - Heap defined by "HEAP" region in .icf file
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* - Interrupt stack defined by "CSTACK" region in .icf file
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* - Value INITIAL_SP is ignored
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*
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* GCC Memory layout :
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* - Heap explicitly placed in linker script (*.ld file) and heap start (__end___) and heap end (__HeapLimit) should be defined in linker script
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* - Interrupt stack placed in linker script **.ld file) and stack start (__StackTop) and stack end (__StackLimit) should be defined in linker script
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*
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* ARM Memory layout :
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* - Heap can be explicitly placed by adding ARM_LIB_HEAP section in scatter file and defining both HEAP_START and HEAP_SIZE
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* - Interrupt stack placed in scatter files (*.sct) by adding ARM_LIB_STACK section
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*
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*/
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#include <stdlib.h>
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#include "cmsis.h"
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#include "mbed_toolchain.h"
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#include "mbed_boot.h"
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#include "mbed_error.h"
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#include "mbed_mpu_mgmt.h"
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int main(void);
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static void mbed_cpy_nvic(void);
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/* Stack limits */
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unsigned char *mbed_stack_isr_start = 0;
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uint32_t mbed_stack_isr_size = 0;
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void mbed_init(void)
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{
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mbed_mpu_manager_init();
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mbed_cpy_nvic();
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mbed_sdk_init();
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mbed_rtos_init();
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}
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void mbed_start(void)
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{
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mbed_toolchain_init();
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mbed_main();
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mbed_error_initialize();
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main();
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}
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MBED_WEAK void mbed_sdk_init(void)
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{
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// Nothing by default
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}
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MBED_WEAK void software_init_hook_rtos()
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{
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// Nothing by default
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}
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MBED_WEAK void mbed_main(void)
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{
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// Nothing by default
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}
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static void mbed_cpy_nvic(void)
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{
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/* If vector address in RAM is defined, copy and switch to dynamic vectors. Exceptions for M0 which doesn't have
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VTOR register and for A9 for which CMSIS doesn't define NVIC_SetVector; in both cases target code is
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responsible for correctly handling the vectors.
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*/
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#if !defined(__CORTEX_M0) && !defined(__CORTEX_A9)
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#ifdef NVIC_RAM_VECTOR_ADDRESS
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uint32_t *old_vectors = (uint32_t *)SCB->VTOR;
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uint32_t *vectors = (uint32_t *)NVIC_RAM_VECTOR_ADDRESS;
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for (int i = 0; i < NVIC_NUM_VECTORS; i++) {
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vectors[i] = old_vectors[i];
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}
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SCB->VTOR = (uint32_t)NVIC_RAM_VECTOR_ADDRESS;
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#endif /* NVIC_RAM_VECTOR_ADDRESS */
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#endif /* !defined(__CORTEX_M0) && !defined(__CORTEX_A9) */
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}
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