/***************************************************************************
 *   Copyright (C) 01/2008 by Olaf Rempel                                  *
 *   razzor@kopf-tisch.de                                                  *
 *                                                                         *
 *   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; version 2 of the License                *
 *                                                                         *
 *   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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include <stdint.h>
#include <stdio.h>
#include "AT91SAM7S256.h"
#include "board.h"
#include "at91_tc1.h"

#define ROUND_DIV256(x) ((x >> 8) + ((x & 0x80) ? 1 : 0))

static uint32_t ppm_arr[MAX_CHANNELS];
static uint32_t ch, cnt, valid;

static void ppm_isr(void)
{
	/* RC Compare -> no TIOA1 edge for 2.5ms */
	uint32_t status = *AT91C_TC1_SR;
	if (status & AT91C_TC_CPCS) {

		/* average channel count */
		cnt = ((cnt * 7) + (ch << 8)) / 8;

		/* at least 4 channels and a stable channel count */
		valid = (ROUND_DIV256(cnt) == ch) && (ch >= 4);

		/* reset index */
		ch = 0;
	}

	/* edge on TIOA1 */
	if (status & AT91C_TC_LDRAS) {
		/* get impulse width */
		uint16_t ra = *AT91C_TC1_RA;

		/* valid range: 1 - 2ms */
		if (ra > 0x0500 && ra < 0x0D00) {
			if (ch < ARRAY_SIZE(ppm_arr))
				ppm_arr[ch] = ((ppm_arr[ch] * 3) + ra) / 4;

			ch++;
		}
	}
}

/*
struct cal_data {
	uint16_t min;
	uint16_t mid;
	uint16_t max;
};

int16_t getval(struct cal_data *cal, uint16_t input)
{
	int32_t x = (input - cal->mid) * 1024;
	uint32_t y = (x > 0) ? (cal->max - cal->mid) : (cal->mid - cal->min);

	return x / y;
}
*/

uint32_t rc_ppm_getvalues(struct rc_values *rc)
{
	uint32_t i;
	rc->count = MIN(ROUND_DIV256(cnt), ARRAY_SIZE(ppm_arr));
	for (i = 0; i < rc->count; i++)
		rc->ch[i] = (ppm_arr[i] - 0x8C0);

	return valid;
}

void at91_tc1_init(void)
{
	/* enable TC1 clock */
	*AT91C_PMC_PCER = (1 << AT91C_ID_TC1);

	/* MCK /32, trigger & capture on falling TIOA1 edge */
	*AT91C_TC1_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK | AT91C_TC_LDRA_FALLING |
			AT91C_TC_ETRGEDG_FALLING | AT91C_TC_ABETRG;

	/* enable RA load and RC compare interrupt */
	*AT91C_TC1_IER = AT91C_TC_LDRAS | AT91C_TC_CPCS;

	/* RC Compare Interrupt if no rising Edge on TIOA1 for 2.56ms */
	*AT91C_TC1_RC = 0x0F00;

	/* enable & trigger the clock */
	*AT91C_TC1_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;

	/* level triggered, own vector */
	AT91S_AIC *aic = AT91C_BASE_AIC;
	aic->AIC_SMR[AT91C_ID_TC1] = IRQPRIO_TC1 | AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL;
	aic->AIC_SVR[AT91C_ID_TC1] = (uint32_t)ppm_isr;
	aic->AIC_IECR = (1 << AT91C_ID_TC1);
}