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RIOT/cpu/efm32/cpu.c
2020-07-08 21:54:57 +02:00

197 lines
4.6 KiB
C

/*
* Copyright (C) 2015-2017 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_efm32
* @{
*
* @file
* @brief Implementation of the CPU initialization
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Bas Stottelaar <basstottelaar@gmail.com>
*
* @}
*/
#include "cpu.h"
#include "periph_conf.h"
#include "periph/init.h"
#include "stdio_base.h"
#include "em_chip.h"
#include "em_cmu.h"
#include "em_emu.h"
/**
* @brief Default settings for CMU initialization.
*/
#ifndef CMU_HFXOINIT
#define CMU_HFXOINIT CMU_HFXOINIT_DEFAULT
#endif
#ifndef CMU_LFXOINIT
#define CMU_LFXOINIT CMU_LFXOINIT_DEFAULT
#endif
/**
* @brief Default settings for EMU initialization
*/
#ifndef EMU_DCDCINIT
#define EMU_DCDCINIT EMU_DCDCINIT_DEFAULT
#endif
#ifndef EMU_EM23INIT
#define EMU_EM23INIT EMU_EM23INIT_DEFAULT
#endif
#ifndef EMU_EM4INIT
#define EMU_EM4INIT EMU_EM4INIT_DEFAULT
#endif
#ifndef RIOTBOOT
#if defined(DCDC_PRESENT) && DCDC_COUNT > 0
/**
* @brief Initialize integrated DC-DC regulator
*/
static void dcdc_init(void)
{
#ifdef EMU_DCDCINIT_OFF
EMU_DCDCPowerOff();
#else
EMU_DCDCInit_TypeDef init_dcdc = EMU_DCDCINIT;
EMU_DCDCInit(&init_dcdc);
#endif
}
#endif
/**
* @brief Configure clock sources and the CPU frequency
*
* On a EFM32 CPU, there are two options for selecting the main clock
* source, using an external clock source (HFXO), or using the internal RC
* oscillator (HFRCO, enabled by default).
*
* The clocks for the LFA, LFB, LFE and HFPER are also configured.
*
* When selecting the HFXO, the HFRCO is disabled. The same applies for the
* LFA, LFB and LFE branch, in case the LFXO is selected.
*/
static void clk_init(void)
{
/* initialize HFXO with board-specific parameters before switching */
if (CLOCK_HF == cmuSelect_HFXO) {
CMU_HFXOInit_TypeDef init_hfxo = CMU_HFXOINIT;
CMU_HFXOInit(&init_hfxo);
}
/* set (and enable) the HF clock source */
CMU_ClockSelectSet(cmuClock_HF, CLOCK_HF);
CMU_ClockDivSet(cmuClock_CORE, CLOCK_CORE_DIV);
/* disable the HFRCO if external crystal is used */
if (CLOCK_HF == cmuSelect_HFXO) {
CMU_OscillatorEnable(cmuOsc_HFRCO, false, false);
}
#if defined(_SILICON_LABS_32B_SERIES_1)
/* disable LFRCO comparator chopping and dynamic element matching
* else LFRCO has too much jitter for LEUART > 1800 baud */
CMU->LFRCOCTRL &= ~(CMU_LFRCOCTRL_ENCHOP | CMU_LFRCOCTRL_ENDEM);
#endif
/* initialize LFXO with board-specific parameters before switching */
if (CLOCK_LFA == cmuSelect_LFXO || CLOCK_LFB == cmuSelect_LFXO ||
#if defined(_SILICON_LABS_32B_SERIES_1)
CLOCK_LFE == cmuSelect_LFXO)
#else
false)
#endif
{
CMU_LFXOInit_TypeDef init_lfxo = CMU_LFXOINIT;
CMU_LFXOInit(&init_lfxo);
}
/* set (and enable) the LFA clock source */
CMU_ClockSelectSet(cmuClock_LFA, CLOCK_LFA);
/* set (and enable) the LFB clock source */
CMU_ClockSelectSet(cmuClock_LFB, CLOCK_LFB);
#if defined(_SILICON_LABS_32B_SERIES_1)
/* set (and enable) the LFE clock source */
CMU_ClockSelectSet(cmuClock_LFE, CLOCK_LFE);
#endif
/* disable the LFRCO if external crystal is used */
if (CLOCK_LFA == cmuSelect_LFXO && CLOCK_LFB == cmuSelect_LFXO &&
#if defined(_SILICON_LABS_32B_SERIES_1)
CLOCK_LFE == cmuSelect_LFXO)
#else
true)
#endif
{
CMU_OscillatorEnable(cmuOsc_LFRCO, false, false);
}
}
/**
* @brief Initialize sleep modes
*
* The EFM32 has several energy saving modes (EM0 - EM4), of which deeper
* modes save more energy.s
*/
static void pm_init(void)
{
/* initialize EM2 and EM3 */
EMU_EM23Init_TypeDef init_em23 = EMU_EM23INIT;
EMU_EM23Init(&init_em23);
#if defined(_SILICON_LABS_32B_SERIES_1)
/* initialize EM4 */
EMU_EM4Init_TypeDef init_em4 = EMU_EM4INIT;
EMU_EM4Init(&init_em4);
#endif
}
#endif
void cpu_init(void)
{
#ifndef RIOTBOOT
/* apply errata that may be applicable (see em_chip.h) */
CHIP_Init();
#endif
/* initialize the Cortex-M core */
cortexm_init();
#ifndef RIOTBOOT
#if defined(DCDC_PRESENT) && DCDC_COUNT > 0
/* initialize dc-dc */
dcdc_init();
#endif
/* initialize clock sources and generic clocks */
clk_init();
/* initialize power management interface */
pm_init();
/* initialize stdio prior to periph_init() to allow use of DEBUG() there */
stdio_init();
/* trigger static peripheral initialization */
periph_init();
#endif
}