mbed-os/rtos/TARGET_CORTEX/mbed_boot.c

/* mbed Microcontroller Library
 * Copyright (c) 2006-2016 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* mbed OS boot sequence
 *
 * Most of mbed supported targets use default ARM Cortex M boot approach, where the core starts executing reset vector
 * after power up. Reset ISR is defined for each target by the vendor (basing on CMSIS template). Reset vector is
 * responsible for low level platform init and then calling in libc (__main). Depending on compiler and version of C
 * library, predefined function will be called which is implemented by mbed OS.
 *
 * There's number of functions, vendor and users can provide to setup the platform and/or inject a code to be executed
 *  before main():
 *      * Reset vector and SystemInit: Reset vector should do low level core and board initialization.
 *      * mbed_sdk_init: Higher level board init and making sure the board is ready for the mbed OS.
 *      * mbed_main: User's code to be executed before main().
 *      * main: Standard application code.
 *
 * Other notes:
 *
 *    * In addition to the above, libc will use functions defined in mbed_boot.c: __rtos_malloc_lock/unlock,
 *      __rtos_env_lock/unlock.
 *
 *    * First step after the execution is passed to mbed, software_init_hook for GCC and __rt_entry for ARMC is to
 *      initialize heap.
 *
 * Memory layout notes:
 * ====================
 *
 * IAR Default Memory layout notes:
 * -Heap defined by "HEAP" region in .icf file
 * -Interrupt stack defined by "CSTACK" region in .icf file
 * -Value INITIAL_SP is ignored
 *
 * IAR Custom Memory layout notes:
 * -There is no custom layout available for IAR - everything must be defined in
 *      the .icf file and use the default layout
 *
 *
 * GCC Default Memory layout notes:
 * -Block of memory from symbol __end__ to define INITIAL_SP used to setup interrupt
 *      stack and heap in the function set_stack_heap()
 * -ISR_STACK_SIZE can be overridden to be larger or smaller
 *
 * GCC Custom Memory layout notes:
 * -Heap can be explicitly placed by defining both HEAP_START and HEAP_SIZE
 * -Interrupt stack can be explicitly placed by defining both ISR_STACK_START and ISR_STACK_SIZE
 *
 *
 * ARM Memory layout
 * -Block of memory from end of region "RW_IRAM1" to define INITIAL_SP used to setup interrupt
 *      stack and heap in the function set_stack_heap()
 * -ISR_STACK_SIZE can be overridden to be larger or smaller
 *
 * ARM Custom Memory layout notes:
 * -Heap can be explicitly placed by defining both HEAP_START and HEAP_SIZE
 * -Interrupt stack can be explicitly placed by defining both ISR_STACK_START and ISR_STACK_SIZE
 *
 */

#include <stdlib.h>

#include "cmsis.h"
#include "mbed_toolchain.h"
#include "mbed_boot.h"

int main(void);
static void mbed_cpy_nvic(void);

/* Stack limits */
unsigned char *mbed_stack_isr_start = 0;
uint32_t mbed_stack_isr_size = 0;

void mbed_init(void)
{
    mbed_cpy_nvic();
    mbed_sdk_init();
    mbed_rtos_init();
}

void mbed_start(void)
{
    mbed_toolchain_init();
    mbed_main();
    main();
}

MBED_WEAK void mbed_sdk_init(void)
{
    // Nothing by default
}

MBED_WEAK void software_init_hook_rtos()
{
    // Nothing by default
}

MBED_WEAK void mbed_main(void)
{
    // Nothing by default
}

static void mbed_cpy_nvic(void)
{
    /* If vector address in RAM is defined, copy and switch to dynamic vectors. Exceptions for M0 which doesn't have
    VTOR register and for A9 for which CMSIS doesn't define NVIC_SetVector; in both cases target code is
    responsible for correctly handling the vectors.
    */
#if !defined(__CORTEX_M0) && !defined(__CORTEX_A9)
#ifdef NVIC_RAM_VECTOR_ADDRESS
    uint32_t *old_vectors = (uint32_t *)SCB->VTOR;
    uint32_t *vectors = (uint32_t *)NVIC_RAM_VECTOR_ADDRESS;
    for (int i = 0; i < NVIC_NUM_VECTORS; i++) {
        vectors[i] = old_vectors[i];
    }
    SCB->VTOR = (uint32_t)NVIC_RAM_VECTOR_ADDRESS;
#endif /* NVIC_RAM_VECTOR_ADDRESS */
#endif /* !defined(__CORTEX_M0) && !defined(__CORTEX_A9) */
}