/*
 * Copyright © 2009 Keith Packard <keithp@keithp.com>
 *
 * 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 "ao.h"

static volatile __data uint16_t ao_tick_count;

uint16_t ao_time(void) __critical
{
	return ao_tick_count;
}

static __xdata uint8_t ao_forever;

void
ao_delay(uint16_t ticks)
{
	ao_alarm(ticks);
	ao_sleep(&ao_forever);
}

#define T1_CLOCK_DIVISOR	8	/* 24e6/8 = 3e6 */
#define T1_SAMPLE_TIME		30000	/* 3e6/30000 = 100 */

#if HAS_ADC
volatile __data uint8_t	ao_adc_interval = 1;
volatile __data uint8_t	ao_adc_count;
#endif

#ifdef AVR
ISR(TIMER1_COMPA_vect)
#else
void ao_timer_isr(void) __interrupt(9)
#endif
{
	++ao_tick_count;
#if HAS_ADC
	if (++ao_adc_count == ao_adc_interval) {
		ao_adc_count = 0;
		ao_adc_poll();
	}
#endif
}

#if HAS_ADC
void
ao_timer_set_adc_interval(uint8_t interval) __critical
{
	ao_adc_interval = interval;
	ao_adc_count = 0;
}
#endif

void
ao_timer_init(void)
{
#ifdef AVR
	TCCR1A = ((0 << WGM11) |	/* CTC mode, OCR1A */
		  (0 << WGM10));	/* CTC mode, OCR1A */
	TCCR1B = ((0 << ICNC1) |	/* no input capture noise canceler */
		  (0 << ICES1) |	/* input capture on falling edge (don't care) */
		  (0 << WGM13) |	/* CTC mode, OCR1A */
		  (1 << WGM12) |	/* CTC mode, OCR1A */
		  (3 << CS10));		/* clk/64 from prescaler */

#if TEENSY
	OCR1A = 2500;			/* 16MHz clock */
#else
	OCR1A = 1250;			/* 8MHz clock */
#endif

	TIMSK1 = (1 << OCIE1A);		/* Interrupt on compare match */
#else
	/* NOTE:  This uses a timer only present on cc1111 architecture. */

	/* disable timer 1 */
	T1CTL = 0;

	/* set the sample rate */
	T1CC0H = T1_SAMPLE_TIME >> 8;
	T1CC0L = (uint8_t) T1_SAMPLE_TIME;

	T1CCTL0 = T1CCTL_MODE_COMPARE;
	T1CCTL1 = 0;
	T1CCTL2 = 0;

	/* clear timer value */
	T1CNTL = 0;

	/* enable overflow interrupt */
	OVFIM = 1;
	/* enable timer 1 interrupt */
	T1IE = 1;

	/* enable timer 1 in module mode, dividing by 8 */
	T1CTL = T1CTL_MODE_MODULO | T1CTL_DIV_8;
#endif
}

/*
 * AltOS always cranks the clock to the max frequency
 */
void
ao_clock_init(void)
{
#ifdef AVR
	/* disable RC clock */
	CLKSEL0 &= ~(1 << RCE);

	/* Disable PLL */
	PLLCSR &= ~(1 << PLLE);

	/* Enable external clock */
	CLKSEL0 |= (1 << EXTE);

	/* wait for external clock to be ready */
	while ((CLKSTA & (1 << EXTON)) == 0)
		;

	/* select external clock */
	CLKSEL0 |= (1 << CLKS);

	/* Disable the clock prescaler */
	cli();
	CLKPR = (1 << CLKPCE);
	CLKPR = 0;
	sei();

	/* Set up the PLL to use the crystal */

	/* Use primary system clock as PLL source */
	PLLFRQ = ((0 << PINMUX) |	/* Use primary clock */
		  (0 << PLLUSB) |	/* No divide by 2 for USB */
		  (0 << PLLTM0) |	/* Disable high speed timer */
		  (0x4 << PDIV0));	/* 48MHz PLL clock */

	/* Set the frequency of the crystal */
#if TEENSY
	PLLCSR |= (1 << PINDIV);	/* For 16MHz crystal on Teensy board */
#else
	PLLCSR &= ~(1 << PINDIV);	/* For 8MHz crystal on TeleScience board */
#endif

	/* Enable the PLL */
	PLLCSR |= (1 << PLLE);
	while (!(PLLCSR & (1 << PLOCK)))
		;
#else
	/* Switch system clock to crystal oscilator */
	CLKCON = (CLKCON & ~CLKCON_OSC_MASK) | (CLKCON_OSC_XTAL);

	while (!(SLEEP & SLEEP_XOSC_STB))
		;

	/* Crank up the timer tick and system clock speed */
	CLKCON = ((CLKCON & ~(CLKCON_TICKSPD_MASK | CLKCON_CLKSPD_MASK)) |
		  (CLKCON_TICKSPD_1 | CLKCON_CLKSPD_1));

	while ((CLKCON & (CLKCON_TICKSPD_MASK|CLKCON_CLKSPD_MASK)) !=
	       (CLKCON_TICKSPD_1 | CLKCON_CLKSPD_1))
		;
#endif
}