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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; 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>
#include <ao_debounce.h>
static uint8_t ao_debounce_initialized;
static uint8_t ao_debounce_running;
static struct ao_debounce *ao_debounce;
static void
ao_debounce_on(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_debounce_off(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));
}
static void
_ao_debounce_set(struct ao_debounce *debounce, uint8_t value)
{
if (value != debounce->value) {
debounce->value = value;
debounce->_set(debounce, value);
}
_ao_debounce_stop(debounce);
}
/*
* Get the current value, set the result when we've
* reached the debounce count limit
*/
static void
_ao_debounce_check(struct ao_debounce *debounce)
{
if (debounce->_get(debounce)) {
if (debounce->count < 0)
debounce->count = 0;
if (debounce->count < debounce->hold) {
if (++debounce->count == debounce->hold)
_ao_debounce_set(debounce, 1);
}
} else {
if (debounce->count > 0)
debounce->count = 0;
if (debounce->count > -debounce->hold) {
if (--debounce->count == -debounce->hold)
_ao_debounce_set(debounce, 0);
}
}
}
/*
* Start monitoring one pin
*/
void
_ao_debounce_start(struct ao_debounce *debounce)
{
if (debounce->running)
return;
debounce->running = 1;
/* Reset the counter */
debounce->count = 0;
/* Link into list */
debounce->next = ao_debounce;
ao_debounce = debounce;
/* Make sure the timer is running */
if (!ao_debounce_running++)
ao_debounce_on();
/* And go check the current value */
_ao_debounce_check(debounce);
}
/*
* Stop monitoring one pin
*/
void
_ao_debounce_stop(struct ao_debounce *debounce)
{
struct ao_debounce **prev;
if (!debounce->running)
return;
debounce->running = 0;
/* Unlink */
for (prev = &ao_debounce; (*prev); prev = &((*prev)->next)) {
if (*prev == debounce) {
*prev = debounce->next;
break;
}
}
debounce->next = NULL;
/* Turn off the timer if possible */
if (!--ao_debounce_running)
ao_debounce_off();
}
void stm_tim6_isr(void)
{
struct ao_debounce *debounce, *next;
if (stm_tim6.sr & (1 << STM_TIM67_SR_UIF)) {
stm_tim6.sr = 0;
/* Walk the current list, allowing the current
* object to be removed from the list
*/
for (debounce = ao_debounce; debounce; debounce = next) {
next = debounce->next;
_ao_debounce_check(debounce);
}
}
}
/*
* 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
#define TIMER_100kHz ((AO_PCLK1 * TIMER_23467_SCALER) / 100000)
void
ao_debounce_init(void)
{
if (ao_debounce_initialized)
return;
ao_debounce_initialized = 1;
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_100kHz;
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);
/* And turn it off (for now) */
ao_debounce_off();
}
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