--- /dev/null
+/*******************************************************************************
+ * Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+ * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Except as contained in this notice, the name of Maxim Integrated
+ * Products, Inc. shall not be used except as stated in the Maxim Integrated
+ * Products, Inc. Branding Policy.
+ *
+ * The mere transfer of this software does not imply any licenses
+ * of trade secrets, proprietary technology, copyrights, patents,
+ * trademarks, maskwork rights, or any other form of intellectual
+ * property whatsoever. Maxim Integrated Products, Inc. retains all
+ * ownership rights.
+ *******************************************************************************
+ */
+
+#include "mbed_error.h"
+#include "us_ticker_api.h"
+#include "PeripheralNames.h"
+#include "tmr_regs.h"
+
+#define US_TIMER MXC_TMR0
+#define US_TIMER_IRQn TMR0_IRQn
+
+static int us_ticker_inited = 0;
+static uint32_t ticks_per_us;
+static uint32_t tick_win;
+static volatile uint64_t current_cnt; // Hold the current ticks
+static volatile uint64_t event_cnt; // Holds the value of the next event
+
+#define ticks_to_us(ticks) ((ticks) / ticks_per_us);
+#define MAX_TICK_VAL ((uint64_t)0xFFFFFFFF * ticks_per_us)
+
+//******************************************************************************
+static inline void inc_current_cnt(uint32_t inc) {
+
+ // Overflow the ticker when the us ticker overflows
+ current_cnt += inc;
+ if(current_cnt > MAX_TICK_VAL) {
+ current_cnt -= (MAX_TICK_VAL + 1);
+ }
+}
+
+//******************************************************************************
+static inline int event_passed(uint64_t current, uint64_t event) {
+
+ // Determine if the event has already happened.
+ // If the event is behind the current ticker, within a window,
+ // then the event has already happened.
+ if(((current < tick_win) && ((event < current) ||
+ (event > (MAX_TICK_VAL - (tick_win - current))))) ||
+ ((event < current) && (event > (current - tick_win)))) {
+ return 1;
+ }
+
+ return 0;
+}
+
+//******************************************************************************
+static inline uint64_t event_diff(uint64_t current, uint64_t event) {
+
+ // Check to see if the ticker will overflow before the event
+ if(current <= event) {
+ return (event - current);
+ }
+
+ return ((MAX_TICK_VAL - current) + event);
+}
+
+//******************************************************************************
+static void tmr_handler(void)
+{
+ uint32_t term_cnt32 = US_TIMER->term_cnt32;
+ US_TIMER->term_cnt32 = 0xFFFFFFFF; // reset to max value to prevent further interrupts
+ US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt
+ NVIC_ClearPendingIRQ(US_TIMER_IRQn);
+
+ inc_current_cnt(term_cnt32);
+
+ if (event_passed(current_cnt + US_TIMER->count32, event_cnt )) {
+ // the timestamp has expired
+ event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value
+ us_ticker_irq_handler();
+ } else {
+
+ uint64_t diff = event_diff(current_cnt, event_cnt);
+ if (diff < (uint64_t)0xFFFFFFFF) {
+ // the event occurs before the next overflow
+ US_TIMER->term_cnt32 = diff;
+
+ // Since the timer keeps counting after the terminal value is reached, it is possible that the new
+ // terminal value is in the past.
+ if (US_TIMER->term_cnt32 < US_TIMER->count32) {
+ // the timestamp has expired
+ US_TIMER->term_cnt32 = 0xFFFFFFFF; // reset to max value to prevent further interrupts
+ US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt
+ NVIC_ClearPendingIRQ(US_TIMER_IRQn);
+ event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value
+ us_ticker_irq_handler();
+ }
+ }
+ }
+}
+
+//******************************************************************************
+void us_ticker_init(void)
+{
+ if (us_ticker_inited)
+ return;
+ us_ticker_inited = 1;
+
+ current_cnt = 0;
+ event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value
+
+ if (SystemCoreClock <= 1000000) {
+ error("us_ticker cannot operate at this SystemCoreClock");
+ return;
+ }
+
+ // Configure timer for 32-bit continuous mode with /1 prescaler
+ US_TIMER->ctrl = MXC_E_TMR_MODE_CONTINUOUS << MXC_F_TMR_CTRL_MODE_POS | (0 << MXC_F_TMR_CTRL_PRESCALE_POS);
+ ticks_per_us = SystemCoreClock / 1000000;
+
+ // Set the tick window to 10ms
+ tick_win = SystemCoreClock/100;
+
+ // Set timer overflow to the max
+ US_TIMER->term_cnt32 = 0xFFFFFFFF;
+ US_TIMER->pwm_cap32 = 0xFFFFFFFF;
+ US_TIMER->count32 = 0;
+
+ US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear pending interrupts
+
+ NVIC_SetVector(US_TIMER_IRQn, (uint32_t)tmr_handler);
+ NVIC_EnableIRQ(US_TIMER_IRQn);
+
+ US_TIMER->inten |= MXC_F_TMR_INTEN_TIMER0; // enable interrupts
+ US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer
+}
+
+//******************************************************************************
+void us_ticker_deinit(void)
+{
+ US_TIMER->ctrl = 0; // disable timer
+ US_TIMER->inten = 0; // disable interrupts
+ US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupts
+ us_ticker_inited = 0;
+}
+
+//******************************************************************************
+uint32_t us_ticker_read(void)
+{
+ uint64_t current_cnt1, current_cnt2;
+ uint32_t term_cnt, tmr_cnt;
+ int intfl1, intfl2;
+
+ if (!us_ticker_inited)
+ us_ticker_init();
+
+ // Ensure coherency between current_cnt and US_TIMER->count32
+ do {
+ current_cnt1 = current_cnt;
+ intfl1 = US_TIMER->intfl;
+ term_cnt = US_TIMER->term_cnt32;
+ tmr_cnt = US_TIMER->count32;
+ intfl2 = US_TIMER->intfl;
+ current_cnt2 = current_cnt;
+ } while ((current_cnt1 != current_cnt2) || (intfl1 != intfl2));
+
+ if (intfl1) {
+ current_cnt1 += term_cnt;
+ }
+
+ current_cnt1 += tmr_cnt;
+
+ return (current_cnt1 / ticks_per_us);
+}
+
+//******************************************************************************
+void us_ticker_set_interrupt(timestamp_t timestamp)
+{
+ // Note: interrupts are disabled before this function is called.
+ US_TIMER->ctrl &= ~MXC_F_TMR_CTRL_ENABLE0; // disable timer
+
+ if (US_TIMER->intfl) {
+ US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt
+ NVIC_ClearPendingIRQ(US_TIMER_IRQn);
+ inc_current_cnt(US_TIMER->term_cnt32);
+ }
+
+ // add and reset the current count value
+ inc_current_cnt(US_TIMER->count32);
+ US_TIMER->count32 = 0;
+
+ // add the number of cycles that the timer is disabled here for
+ inc_current_cnt(200);
+
+ event_cnt = (uint64_t)timestamp * ticks_per_us;
+
+ // Check to see if the event has already passed
+ if (!event_passed(current_cnt, event_cnt)) {
+ uint64_t diff = event_diff(current_cnt, event_cnt);
+ if (diff < (uint64_t)0xFFFFFFFF) {
+ // the event occurs before the next overflow
+ US_TIMER->term_cnt32 = diff;
+ } else {
+ // the event occurs after the next overflow
+ US_TIMER->term_cnt32 = 0xFFFFFFFF; // set to max
+ }
+ } else {
+ // the requested timestamp occurs in the past
+ // set the timer up to immediately expire
+ US_TIMER->term_cnt32 = 1;
+ }
+ US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer
+}
+
+//******************************************************************************
+void us_ticker_disable_interrupt(void)
+{
+ // There are no more events, set timer overflow to the max
+ US_TIMER->term_cnt32 = 0xFFFFFFFF;
+}
+
+//******************************************************************************
+void us_ticker_clear_interrupt(void)
+{
+ // cleared in the local handler
+}
+
+//******************************************************************************
+void us_ticker_set(timestamp_t timestamp)
+{
+ US_TIMER->ctrl &= ~MXC_F_TMR_CTRL_ENABLE0; // disable timer
+ current_cnt = (uint64_t)timestamp * ticks_per_us;
+ US_TIMER->count32 = 0;
+ US_TIMER->term_cnt32 = 0xFFFFFFFF;
+ US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer
+
+ if (((uint64_t)timestamp * ticks_per_us) >= event_cnt) {
+ // The next timestamp has elapsed. Trigger the interrupt to handle it.
+ NVIC_SetPendingIRQ(US_TIMER_IRQn);
+ }
+}
projects / qmk_firmware.git / blobdiff