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/** @addtogroup rtc_file */

/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

/**@{*/

#include <libopencm3/stm32/rtc.h>

/*---------------------------------------------------------------------------*/
/** @brief Set RTC prescalars.

This sets the RTC synchronous and asynchronous prescalars.
*/

void rtc_set_prescaler(u32 sync, u32 async) {
	/*
	 * Even if only one of the two fields needs to be changed,
	 * 2 separate write accesses must be performed to the RTC_PRER register.
	 */
	RTC_PRER = (sync & RTC_PRER_PREDIV_S_MASK);
	RTC_PRER |= (async << RTC_PRER_PREDIV_A_SHIFT);
}

/*---------------------------------------------------------------------------*/
/** @brief Wait for RTC registers to be synchronised with the APB1 bus

 Time and Date are accessed through shadow registers which must be synchronized
*/

void rtc_wait_for_synchro(void) {
	/* Unlock RTC registers */
	RTC_WPR = 0xca;
	RTC_WPR = 0x53;

	RTC_ISR &= ~(RTC_ISR_RSF);

	while (!(RTC_ISR & RTC_ISR_RSF)) {
		;
	}
	/* disable write protection again */
	RTC_WPR = 0xff;
}

/*---------------------------------------------------------------------------*/
/** @brief Unlock write access to the RTC registers

*/
void rtc_unlock(void) {
	RTC_WPR = 0xca;
	RTC_WPR = 0x53;
}

/*---------------------------------------------------------------------------*/
/** @brief Lock write access to the RTC registers

*/
void rtc_lock(void) {
	RTC_WPR = 0xff;
}

/**@}*/