t
Fork of mbed-dev by
targets/TARGET_Maxim/TARGET_MAX32630/us_ticker.c
- Committer:
- amithy
- Date:
- 2017-11-09
- Revision:
- 178:c26431f84b0d
- Parent:
- 157:ff67d9f36b67
- Child:
- 165:e614a9f1c9e2
File content as of revision 178:c26431f84b0d:
/******************************************************************************* * Copyright (c) 2016 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 <stddef.h> #include "mbed_error.h" #include "us_ticker_api.h" #include "PeripheralNames.h" #include "tmr.h" #define US_TIMER MXC_TMR0 #define US_TIMER_IRQn TMR0_0_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 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 cmp = TMR32_GetCompare(US_TIMER); TMR32_SetCompare(US_TIMER, 0xFFFFFFFF); // reset to max value to prevent further interrupts TMR32_ClearFlag(US_TIMER); NVIC_ClearPendingIRQ(US_TIMER_IRQn); inc_current_cnt(cmp); if (event_passed(current_cnt + TMR32_GetCount(US_TIMER), 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 TMR32_SetCompare(US_TIMER, 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 (TMR32_GetCompare(US_TIMER) < TMR32_GetCount(US_TIMER)) { // the timestamp has expired TMR32_SetCompare(US_TIMER, 0xFFFFFFFF); // reset to max value to prevent further interrupts TMR32_ClearFlag(US_TIMER); 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 ticks_per_us = SystemCoreClock / 1000000; tick_win = SystemCoreClock / 100; // Set the tick window to 10ms int retval = TMR_Init(US_TIMER, TMR_PRESCALE_DIV_2_0, NULL); MBED_ASSERT(retval == E_NO_ERROR); tmr32_cfg_t cfg; cfg.mode = TMR32_MODE_CONTINUOUS; cfg.polarity = TMR_POLARITY_UNUSED; cfg.compareCount = 0xFFFFFFFF; TMR32_Config(US_TIMER, &cfg); NVIC_SetVector(US_TIMER_IRQn, tmr_handler); NVIC_EnableIRQ(US_TIMER_IRQn); TMR32_EnableINT(US_TIMER); TMR32_Start(US_TIMER); } //****************************************************************************** void us_ticker_deinit(void) { TMR32_Stop(US_TIMER); TMR32_DisableINT(US_TIMER); TMR32_ClearFlag(US_TIMER); us_ticker_inited = 0; } //****************************************************************************** uint32_t us_ticker_read(void) { uint64_t current_cnt1, current_cnt2; uint32_t cmp, cnt; uint32_t flag1, flag2; if (!us_ticker_inited) { us_ticker_init(); } // Ensure coherency between current_cnt and TMR32_GetCount() do { current_cnt1 = current_cnt; flag1 = TMR32_GetFlag(US_TIMER); cmp = TMR32_GetCompare(US_TIMER); cnt = TMR32_GetCount(US_TIMER); flag2 = TMR32_GetFlag(US_TIMER); current_cnt2 = current_cnt; } while ((current_cnt1 != current_cnt2) || (flag1 != flag2)); // Account for an unserviced interrupt if (flag1) { current_cnt1 += cmp; } current_cnt1 += cnt; return (current_cnt1 / ticks_per_us); } //****************************************************************************** void us_ticker_set_interrupt(timestamp_t timestamp) { // Note: interrupts are disabled before this function is called. TMR32_Stop(US_TIMER); if (TMR32_GetFlag(US_TIMER)) { TMR32_ClearFlag(US_TIMER); NVIC_ClearPendingIRQ(US_TIMER_IRQn); inc_current_cnt(TMR32_GetCompare(US_TIMER)); } // add and reset the current count value inc_current_cnt(TMR32_GetCount(US_TIMER)); TMR32_SetCount(US_TIMER, 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 TMR32_SetCompare(US_TIMER, diff); } else { // the event occurs after the next overflow TMR32_SetCompare(US_TIMER, 0xFFFFFFFF); // set to max } } else { // the requested timestamp occurs in the past // set the timer up to immediately expire TMR32_SetCompare(US_TIMER, 1); } TMR32_Start(US_TIMER); } //****************************************************************************** void us_ticker_disable_interrupt(void) { // There are no more events, set timer overflow to the max TMR32_SetCompare(US_TIMER, 0xFFFFFFFF); } //****************************************************************************** void us_ticker_clear_interrupt(void) { // cleared in the local handler } //****************************************************************************** void us_ticker_set(timestamp_t timestamp) { TMR32_Stop(US_TIMER); current_cnt = (uint64_t)timestamp * ticks_per_us; TMR32_SetCount(US_TIMER, 0); TMR32_SetCompare(US_TIMER, 0xFFFFFFFF); TMR32_Start(US_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); } }