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/** \addtogroup rtng_module Working with RTNG
 * \ingroup peripherals_module
 * The TRNG driver provides the interface to configure and use the TRNG
 * peripheral.
 * \n
 *
 * The True Random Number Generator (TRNG) passes the American NIST Special
 * Publication 800-22 and Diehard Random Tests Suites. As soon as the TRNG is
 * enabled (trng_enable()), the generator provides one 32-bit value every 84
 * clock cycles.  TRNG Interrupt can be enabled through trng_enable_it()
 * (respectively disabled with trng_disable_it()).  When new random data is
 * ready, the interrupt will fire and the configured callback will be called.
 * Alternatively, the TRNG can also be used in polling mode using
 * trng_get_random_data().
 *
 * For more accurate information, please look at the TRNG section of the
 * datasheet.
 *
 * Related files :\n
 * \ref trng.c\n
 * \ref trng.h\n
 */
/*@{*/
/*@}*/

/**
 * \file
 *
 * Implementation of True Random Number Generator (TRNG)
 *
 */

/*----------------------------------------------------------------------------
 *        Headers
 *----------------------------------------------------------------------------*/

#include "chip.h"
#include "peripherals/aic.h"
#include "peripherals/pmc.h"
#include "peripherals/trng.h"

/*----------------------------------------------------------------------------
 *        Local Data
 *----------------------------------------------------------------------------*/

static trng_callback_t _trng_callback;
static void*           _trng_callback_arg;

/*------------------------------------------------------------------------------
 *         Local functions
 *------------------------------------------------------------------------------*/

static void _trng_handler(void)
{
	if (TRNG->TRNG_ISR & TRNG_ISR_DATRDY) {
		if (_trng_callback) {
			_trng_callback(TRNG->TRNG_ODATA, _trng_callback_arg);
		}
	}
}

/*------------------------------------------------------------------------------
 *         Exported functions
 *------------------------------------------------------------------------------*/

void trng_enable()
{
	pmc_enable_peripheral(ID_TRNG);
	TRNG->TRNG_CR = TRNG_CR_ENABLE | TRNG_CR_KEY_PASSWD;
}

void trng_disable()
{
	TRNG->TRNG_CR = TRNG_CR_KEY_PASSWD;
	pmc_disable_peripheral(ID_TRNG);
}

void trng_enable_it(trng_callback_t cb, void* user_arg)
{
	_trng_callback = cb;
	_trng_callback_arg = user_arg;
	aic_set_source_vector(ID_TRNG, _trng_handler);
	aic_enable(ID_TRNG);
	TRNG->TRNG_IER = TRNG_IER_DATRDY;
}

void trng_disable_it(void)
{
	TRNG->TRNG_IDR = TRNG_IDR_DATRDY;
	aic_disable(ID_TRNG);
	_trng_callback = NULL;
	_trng_callback_arg = NULL;
}

uint32_t trng_get_random_data(void)
{
	while (!(TRNG->TRNG_ISR & TRNG_ISR_DATRDY));
	return TRNG->TRNG_ODATA;
}