[libopenstm32-devel] RTC functions

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/*
 * This file is part of the libopenstm32 project.
 *
 * Copyright (C) 2010 Uwe Hermann <uw...@he...>
 * Copyright (C) 2010 Lord James <lor...@y7...>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <libopenstm32/rcc.h>
#include <libopenstm32/rtc.h>
#include <libopenstm32/pwr.h>

void rtc_awake_from_off(osc_t clock_source)
{
	u32 reg32;

	/* Enable power and backup interface clocks. */
	RCC_APB1ENR |= (RCC_APB1ENR_PWREN | RCC_APB1ENR_BKPEN);

	/* Enable access to the backup registers and the RTC. */
	PWR_CR |= PWR_CR_DBP;

	/*
	 * Reset the backup domain, clears everything RTC related.
	 * If not wanted use the rtc_awake_from_standby() function.
	 */
	rcc_backupdomain_reset();

	switch (clock_source) {
	case LSE:
		/* Turn the LSE on and wait while it stabilises. */
		RCC_BDCR |= RCC_BDCR_LSEON;
		while ((reg32 = (RCC_BDCR & RCC_BDCR_LSERDY)) == 0);

		/* Choose LSE as the RTC clock source. */
		RCC_BDCR &= ~((1 << 8) | (1 << 9));
		RCC_BDCR |= (1 << 8);
		break;
	case LSI:
		/* Turn the LSI on and wait while it stabilises. */
		RCC_CSR |= RCC_CSR_LSION;
		while ((reg32 = (RCC_CSR & RCC_CSR_LSIRDY)) == 0);

		/* Choose LSI as the RTC clock source. */
		RCC_BDCR &= ~((1 << 8) | (1 << 9));
		RCC_BDCR |= (1 << 9);
		break;
	case HSE:
		/* Turn the HSE on and wait while it stabilises. */
		RCC_CR |= RCC_CR_HSEON;
		while ((reg32 = (RCC_CR & RCC_CR_HSERDY)) == 0);

		/* Choose HSE as the RTC clock source. */
		RCC_BDCR &= ~((1 << 8) | (1 << 9));
		RCC_BDCR |= (1 << 9) | (1 << 8);
		break;
	case PLL:
	case HSI:
		/* Unusable clock source, here to prevent warnings. */
		/* Turn off clock sources to RTC. */
		RCC_BDCR &= ~((1 << 8) | (1 << 9));
		break;
	}

	/* Enable the RTC. */
	RCC_BDCR |= RCC_BDCR_RTCEN;

	/* Wait for the RSF bit in RTC_CRL to be set by hardware. */
	RTC_CRL &= ~RTC_CRL_RSF;
	while ((reg32 = (RTC_CRL & RTC_CRL_RSF)) == 0);

	/* Wait for the last write operation to finish. */
	/* TODO: Necessary? */
	while ((reg32 = (RTC_CRL & RTC_CRL_RTOFF)) == 0);
}

void rtc_enter_config_mode(void)
{
	u32 reg32;

	/* Wait until the RTOFF bit is 1 (no RTC register writes ongoing). */
	while ((reg32 = (RTC_CRL & RTC_CRL_RTOFF)) == 0);

	/* Enter configuration mode. */
	RTC_CRL |= RTC_CRL_CNF;
}

void rtc_exit_config_mode(void)
{
	/* u32 reg32; */

	/* Exit configuration mode. */
	RTC_CRL &= ~RTC_CRL_CNF;

	/* Wait until the RTOFF bit is 1 (our RTC register write finished). */
	/* while ((reg32 = (RTC_CRL & RTC_CRL_RTOFF)) == 0); */
	/* TODO: Unnecessary since we poll the bit on config entry(?) */
}

void rtc_set_alarm_time(u32 alarm_time)
{
	rtc_enter_config_mode();
	RTC_ALRL = (alarm_time & 0x0000ffff);
	RTC_ALRH = (alarm_time & 0xffff0000) >> 16;
	rtc_exit_config_mode();
}

void rtc_enable_alarm(void)
{
	rtc_enter_config_mode();
	RTC_CRH |= RTC_CRH_ALRIE;
	rtc_exit_config_mode();
}

void rtc_disable_alarm(void)
{
	rtc_enter_config_mode();
	RTC_CRH &= ~RTC_CRH_ALRIE;
	rtc_exit_config_mode();
}

void rtc_set_prescale_val(u32 prescale_val)
{
	rtc_enter_config_mode();
	RTC_PRLL = prescale_val & 0x0000ffff;         /* PRL[15:0] */
	RTC_PRLH = (prescale_val & 0x000f0000) >> 16; /* PRL[19:16] */
	rtc_exit_config_mode();
}

u32 rtc_get_counter_val(void)
{
	return (RTC_CNTH << 16) | RTC_CNTL;
}

u32 rtc_get_prescale_div_val(void)
{
	return (RTC_DIVH << 16) | RTC_DIVL;
}

u32 rtc_get_alarm_val(void)
{
	return (RTC_ALRH << 16) | RTC_ALRL;
}

void rtc_set_counter_val(u32 counter_val)
{
	rtc_enter_config_mode();
	RTC_CNTH = (counter_val & 0xffff0000) >> 16; /* CNT[31:16] */
	RTC_CNTL = counter_val & 0x0000ffff;         /* CNT[15:0] */
	rtc_exit_config_mode();
}

void rtc_interrupt_enable(rtcflag_t flag_val)
{
	rtc_enter_config_mode();

	/* Set the correct interrupt enable. */
	switch(flag_val) {
	case RTC_SEC:
		RTC_CRH |= RTC_CRH_SECIE;
		break;
	case RTC_ALR:
		RTC_CRH |= RTC_CRH_ALRIE;
		break;
	case RTC_OW:
		RTC_CRH |= RTC_CRH_OWIE;
		break;
	}

	rtc_exit_config_mode();
}

void rtc_interrupt_disable(rtcflag_t flag_val)
{
	rtc_enter_config_mode();

	/* Disable the correct interrupt enable. */
	switch(flag_val) {
	case RTC_SEC:
		RTC_CRH &= ~RTC_CRH_SECIE;
		break;
	case RTC_ALR:
		RTC_CRH &= ~RTC_CRH_ALRIE;
		break;
	case RTC_OW:
		RTC_CRH &= ~RTC_CRH_OWIE;
		break;
	}

	rtc_exit_config_mode();
}

void rtc_clear_flag(rtcflag_t flag_val)
{
	/* Configuration mode not needed. */

	/* Clear the correct flag. */
	switch(flag_val) {
	case RTC_SEC:
		RTC_CRL &= ~RTC_CRL_SECF;
		break;
	case RTC_ALR:
		RTC_CRL &= ~RTC_CRL_ALRF;
		break;
	case RTC_OW:
		RTC_CRL &= ~RTC_CRL_OWF;
		break;
	}
}

u32 rtc_check_flag(rtcflag_t flag_val)
{
	u32 reg32;

	/* Read correct flag. */
	switch(flag_val) {
	case RTC_SEC:
		reg32 = RTC_CRL & RTC_CRL_SECF;
		break;
	case RTC_ALR:
		reg32 = RTC_CRL & RTC_CRL_ALRF;
		break;
	case RTC_OW:
		reg32 = RTC_CRL & RTC_CRL_OWF;
		break;
	default:
		reg32 = 0;
		break;
	}

	return reg32;
}

void rtc_awake_from_standby(void)
{
	u32 reg32;

	/* Enable power and backup interface clocks. */
	RCC_APB1ENR |= (RCC_APB1ENR_PWREN | RCC_APB1ENR_BKPEN);

	/* Enable access to the backup registers and the RTC. */
	PWR_CR |= PWR_CR_DBP;

	/* Wait for the RSF bit in RTC_CRL to be set by hardware. */
	RTC_CRL &= ~RTC_CRL_RSF;
	while ((reg32 = (RTC_CRL & RTC_CRL_RSF)) == 0);

	/* Wait for the last write operation to finish. */
	/* TODO: Necessary? */
	while ((reg32 = (RTC_CRL & RTC_CRL_RTOFF)) == 0);
}

void rtc_auto_awake(osc_t clock_source, u32 prescale_val)
{
	u32 reg32;

	/* Enable power and backup interface clocks. */
	RCC_APB1ENR |= (RCC_APB1ENR_PWREN | RCC_APB1ENR_BKPEN);

	/* Enable access to the backup registers and the RTC. */
	/* TODO: Not sure if this is necessary to just read the flag. */
	PWR_CR |= PWR_CR_DBP;

	if ((reg32 = RCC_BDCR & RCC_BDCR_RTCEN) != 0) {
		rtc_awake_from_standby();
	} else {
		rtc_awake_from_off(clock_source);
		rtc_set_prescale_val(prescale_val);
	}
}