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/*
* Copyright © 2013 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; either version 2 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, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#include <ao.h>
#include <ao_fast_timer.h>
static void (*ao_fast_timer_callback[AO_FAST_TIMER_MAX])(void);
static uint8_t ao_fast_timer_count;
static uint8_t ao_fast_timer_users;
static void
ao_fast_timer_enable(void)
{
stm_tim6.cr1 = ((0 << STM_TIM67_CR1_ARPE) |
(0 << STM_TIM67_CR1_OPM) |
(1 << STM_TIM67_CR1_URS) |
(0 << STM_TIM67_CR1_UDIS) |
(1 << STM_TIM67_CR1_CEN));
}
static void
ao_fast_timer_disable(void)
{
stm_tim6.cr1 = ((0 << STM_TIM67_CR1_ARPE) |
(0 << STM_TIM67_CR1_OPM) |
(1 << STM_TIM67_CR1_URS) |
(0 << STM_TIM67_CR1_UDIS) |
(0 << STM_TIM67_CR1_CEN));
}
void
ao_fast_timer_on(void (*callback)(void))
{
ao_fast_timer_callback[ao_fast_timer_count] = callback;
if (!ao_fast_timer_count++)
ao_fast_timer_enable();
}
void
ao_fast_timer_off(void (*callback)(void))
{
uint8_t n;
for (n = 0; n < ao_fast_timer_count; n++)
if (ao_fast_timer_callback[n] == callback) {
for (; n < ao_fast_timer_count-1; n++) {
ao_fast_timer_callback[n] = ao_fast_timer_callback[n+1];
}
if (!--ao_fast_timer_count)
ao_fast_timer_disable();
break;
}
}
void stm_tim6_isr(void)
{
uint8_t i;
if (stm_tim6.sr & (1 << STM_TIM67_SR_UIF)) {
stm_tim6.sr = 0;
for (i = 0; i < ao_fast_timer_count; i++)
(*ao_fast_timer_callback[i])();
}
}
/*
* According to the STM clock-configuration, timers run
* twice as fast as the APB1 clock *if* the APB1 prescaler
* is greater than 1.
*/
#if AO_APB1_PRESCALER > 1
#define TIMER_23467_SCALER 2
#else
#define TIMER_23467_SCALER 1
#endif
#ifndef FAST_TIMER_FREQ
#define FAST_TIMER_FREQ 10000
#endif
#define TIMER_FAST ((AO_PCLK1 * TIMER_23467_SCALER) / FAST_TIMER_FREQ)
void
ao_fast_timer_init(void)
{
if (!ao_fast_timer_users) {
stm_nvic_set_enable(STM_ISR_TIM6_POS);
stm_nvic_set_priority(STM_ISR_TIM6_POS, AO_STM_NVIC_CLOCK_PRIORITY);
/* Turn on timer 6 */
stm_rcc.apb1enr |= (1 << STM_RCC_APB1ENR_TIM6EN);
stm_tim6.psc = TIMER_FAST;
stm_tim6.arr = 9;
stm_tim6.cnt = 0;
/* Enable update interrupt */
stm_tim6.dier = (1 << STM_TIM67_DIER_UIE);
/* Poke timer to reload values */
stm_tim6.egr |= (1 << STM_TIM67_EGR_UG);
stm_tim6.cr2 = (STM_TIM67_CR2_MMS_RESET << STM_TIM67_CR2_MMS);
ao_fast_timer_disable();
}
if (ao_fast_timer_users == AO_FAST_TIMER_MAX)
ao_panic(AO_PANIC_FAST_TIMER);
ao_fast_timer_users++;
}
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