-/*
- * 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();
-}