147 lines
6.3 KiB
C
147 lines
6.3 KiB
C
/************************************************************************************//**
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* \file Source/ARMCM4_STM32L4/timer.c
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* \brief Bootloader timer driver source file.
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* \ingroup Target_ARMCM4_STM32L4
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* \internal
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*----------------------------------------------------------------------------------------
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* C O P Y R I G H T
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*----------------------------------------------------------------------------------------
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* Copyright (c) 2018 by Feaser http://www.feaser.com All rights reserved
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*
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*----------------------------------------------------------------------------------------
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* L I C E N S E
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*----------------------------------------------------------------------------------------
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* This file is part of OpenBLT. OpenBLT is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* OpenBLT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You have received a copy of the GNU General Public License along with OpenBLT. It
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* should be located in ".\Doc\license.html". If not, contact Feaser to obtain a copy.
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*
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* \endinternal
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****************************************************************************************/
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/****************************************************************************************
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* Include files
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****************************************************************************************/
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#include "boot.h" /* bootloader generic header */
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#include "stm32l4xx.h" /* STM32 CPU and HAL header */
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/****************************************************************************************
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* Local data declarations
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****************************************************************************************/
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/** \brief Local variable for storing the number of milliseconds that have elapsed since
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* startup.
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*/
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static blt_int32u millisecond_counter;
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/************************************************************************************//**
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** \brief Initializes the polling based millisecond timer driver.
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** \return none.
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**
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****************************************************************************************/
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void TimerInit(void)
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{
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/* Reset the timer configuration. */
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TimerReset();
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/* Configure the systick frequency as a 1 ms event generator. */
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SysTick->LOAD = BOOT_CPU_SYSTEM_SPEED_KHZ - 1;
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/* Reset the current counter value. */
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SysTick->VAL = 0;
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/* Select core clock as source and enable the timer. */
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SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk;
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/* Reset the millisecond counter value. */
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millisecond_counter = 0;
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} /*** end of TimerInit ***/
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/************************************************************************************//**
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** \brief Reset the timer by placing the timer back into it's default reset
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** configuration.
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** \return none.
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**
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****************************************************************************************/
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void TimerReset(void)
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{
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/* Set the systick's registers back into the default reset value. */
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SysTick->CTRL = 0;
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SysTick->LOAD = 0;
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SysTick->VAL = 0;
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} /* end of TimerReset */
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/************************************************************************************//**
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** \brief Updates the millisecond timer.
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** \return none.
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**
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****************************************************************************************/
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void TimerUpdate(void)
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{
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/* Check if the millisecond event occurred. */
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if ((SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk) != 0)
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{
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/* Increment the millisecond counter. */
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millisecond_counter++;
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}
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} /*** end of TimerUpdate ***/
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/************************************************************************************//**
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** \brief Obtains the counter value of the millisecond timer.
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** \return Current value of the millisecond timer.
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**
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****************************************************************************************/
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blt_int32u TimerGet(void)
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{
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/* Updating timer here allows this function to be called in a loop with timeout
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* detection.
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*/
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TimerUpdate();
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/* Read and return the amount of milliseconds that passed since initialization. */
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return millisecond_counter;
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} /*** end of TimerGet ***/
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/************************************************************************************//**
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** \brief Override for the HAL driver's GetTick() functionality. This is needed
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** because the bootloader doesn't use interrupts, but the HAL's tick
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** functionality assumes that it does. This will cause the HAL_Delay()
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** function to not work properly. As a result of this override, the HAL's
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** tick functionality works in polling mode.
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** \return Current value of the millisecond timer.
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**
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****************************************************************************************/
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uint32_t HAL_GetTick(void)
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{
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/* Link to the bootloader's 1ms timer. */
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return TimerGet();
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} /*** end of HAL_GetTick ***/
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/************************************************************************************//**
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** \brief This function handles the SysTick interrupt. The HAL driver is initialized
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** before this timer driver. The HAL driver configures the SysTick for
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** interrupt driven mode, which is afterwards disabled by the timer driver
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** initialization. It is theoretically possible that the SysTick interrupt
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** still fires before the timer driver disables it. Therefore the handler
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** is implemented here. If not, then the default handler from cstart.s is
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** used, which hangs the system.
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** \return none.
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**
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****************************************************************************************/
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void SysTick_Handler(void)
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{
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/* Nothing to do here. */
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} /*** end of SysTick_Handler ***/
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/*********************************** end of timer.c ************************************/
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