altos: Add fast-timer API. Use for quadrature and button drivers

[fw/altos] / src / stm / ao_fast_timer.c

diff --git a/src/stm/ao_fast_timer.c b/src/stm/ao_fast_timer.c
new file mode 100644 (file)
index 0000000..d61b40c
--- /dev/null
+++ b/src/stm/ao_fast_timer.c
@@ -0,0 +1,120 @@
+/*
+ * 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_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
+
+#define TIMER_10kHz    ((AO_PCLK1 * TIMER_23467_SCALER) / 10000)
+
+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_10kHz;
+               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++;
+}
+