RIOT/cpu/saml1x/cpu.c

/*
 * Copyright (C) 2018 Mesotic SAS
 *
 * 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_saml1x
 * @{
 *
 * @file        cpu.c
 * @brief       Implementation of the CPU initialization for Microchip
 *              SAML10/SAML11 MCUs
 *
 * @author      Dylan Laduranty <dylan.laduranty@mesotic.com>
 * @}
 */

#include "cpu.h"
#include "kernel_init.h"
#include "periph/init.h"
#include "periph_conf.h"
#include "board.h"
#include "stdio_base.h"

#ifdef CPU_FAM_SAML11
#define _NVMCTRL NVMCTRL_SEC
#else
#define _NVMCTRL NVMCTRL
#endif

/* As long as FDPLL is not used, we can default to
 * always using the buck converter.
 *
 * An external inductor needs to be present on the board,
 * so the feature can only be enabled by the board configuration.
 */
#ifndef USE_VREG_BUCK
#define USE_VREG_BUCK (0)
#endif

static void _gclk_setup(int gclk, uint32_t reg)
{
    GCLK->GENCTRL[gclk].reg = reg;
    while (GCLK->SYNCBUSY.reg & GCLK_SYNCBUSY_GENCTRL(gclk)) {}
}

static void _osc32k_setup(void)
{
#if INTERNAL_OSC32_SOURCE
    uint32_t * pCalibrationArea;
    uint32_t osc32kcal;

    /* Read OSC32KCAL, calibration data for OSC32 !!! */
    pCalibrationArea = (uint32_t*) NVMCTRL_OTP5;
    osc32kcal = ( (*pCalibrationArea) & 0x1FC0 ) >> 6;

    /* RTC use Low Power Internal Oscillator at 32kHz */
    OSC32KCTRL->OSC32K.reg = OSC32KCTRL_OSC32K_RUNSTDBY
                           | OSC32KCTRL_OSC32K_EN32K
                           | OSC32KCTRL_OSC32K_CALIB(osc32kcal)
                           | OSC32KCTRL_OSC32K_ENABLE;

    /* Wait OSC32K Ready */
    while (!(OSC32KCTRL->STATUS.reg & OSC32KCTRL_STATUS_OSC32KRDY)) {}
#endif /* INTERNAL_OSC32_SOURCE */
}

static void _xosc32k_setup(void)
{
#if EXTERNAL_OSC32_SOURCE
    /* RTC uses External 32,768KHz Oscillator */
    OSC32KCTRL->XOSC32K.reg = OSC32KCTRL_XOSC32K_XTALEN
                            | OSC32KCTRL_XOSC32K_RUNSTDBY
                            | OSC32KCTRL_XOSC32K_EN32K
                            | OSC32KCTRL_XOSC32K_ENABLE;

    /* Wait XOSC32K Ready */
    while (!(OSC32KCTRL->STATUS.reg & OSC32KCTRL_STATUS_XOSC32KRDY)) {}
#endif
}

void sam0_gclk_enable(uint8_t id)
{
    (void) id;
    /* clocks are always running */
}

uint32_t sam0_gclk_freq(uint8_t id)
{
    switch (id) {
    case SAM0_GCLK_MAIN:
        return CLOCK_CORECLOCK;
    case SAM0_GCLK_32KHZ:
        return 32768;
    default:
        return 0;
    }
}

void cpu_pm_cb_enter(int deep)
{
    (void) deep;
    /* will be called before entering sleep */
}

void cpu_pm_cb_leave(int deep)
{
    (void) deep;
    /* will be called after wake-up */
}

/**
 * @brief Initialize the CPU, set IRQ priorities, clocks
 */
void cpu_init(void)
{
    /* initialize the Cortex-M core */
    cortexm_init();

    /* not compatible with 96 MHz FDPLL */
    if (USE_VREG_BUCK) {
        sam0_set_voltage_regulator(SAM0_VREG_BUCK);
    }

    /* turn on only needed APB peripherals */
    MCLK->APBAMASK.reg = MCLK_APBAMASK_MCLK
                         | MCLK_APBAMASK_OSCCTRL
                         | MCLK_APBAMASK_OSC32KCTRL
                         | MCLK_APBAMASK_GCLK
                         | MCLK_APBAMASK_PM
#ifdef MODULE_PERIPH_GPIO_IRQ
                         | MCLK_APBAMASK_EIC
#endif
#ifdef MODULE_PERIPH_GPIO
                         | MCLK_APBAMASK_PORT
#endif
#ifdef MODULE_PERIPH_RTC_RTT
                         | MCLK_APBAMASK_RTC
#endif
                         ;

    /* Disable the RTC module to prevent synchronization issues during CPU init
       if the RTC was running from a previous boot (e.g wakeup from backup)
       as the module will be re-init during the boot process */
    if ((RTC->MODE2.CTRLA.reg & RTC_MODE2_CTRLA_ENABLE) &&
        IS_ACTIVE(MODULE_PERIPH_RTC_RTT)) {
        while (RTC->MODE2.SYNCBUSY.reg) {}
        RTC->MODE2.CTRLA.reg &= ~ RTC_MODE2_CTRLA_ENABLE;
        while (RTC->MODE2.SYNCBUSY.reg) {}
    }
    /* Software reset the GCLK module to ensure it is re-initialized correctly */
    GCLK->CTRLA.reg = GCLK_CTRLA_SWRST;
    while (GCLK->CTRLA.reg & GCLK_CTRLA_SWRST) {}
    while (GCLK->SYNCBUSY.reg & GCLK_SYNCBUSY_SWRST) {}

    PM->PLCFG.reg = PM_PLCFG_PLSEL_PL2;
    while (!(PM->INTFLAG.reg & PM_INTFLAG_PLRDY)) {}

    MCLK->APBBMASK.reg |= MCLK_APBBMASK_NVMCTRL;
    _NVMCTRL->CTRLB.reg |= NVMCTRL_CTRLB_RWS(1);
    MCLK->APBBMASK.reg &= ~MCLK_APBBMASK_NVMCTRL;

    /* set OSC16M to 16MHz */
    OSCCTRL->OSC16MCTRL.reg = (OSCCTRL_OSC16MCTRL_FSEL_16 | OSCCTRL_OSC16MCTRL_ENABLE);

    _osc32k_setup();
    _xosc32k_setup();

    /* Setup GCLK generators */
    _gclk_setup(SAM0_GCLK_MAIN, GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSC16M);
#if EXTERNAL_OSC32_SOURCE
    _gclk_setup(SAM0_GCLK_32KHZ, GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_XOSC32K);
#else
    _gclk_setup(SAM0_GCLK_32KHZ, GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K);
#endif

#ifdef MODULE_PERIPH_DMA
    /*  initialize DMA streams */
    dma_init();
#endif

    /* initialize stdio prior to periph_init() to allow use of DEBUG() there */
    early_init();

    /* trigger static peripheral initialization */
    periph_init();
}