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targets/TARGET_Maxim/TARGET_MAX32620/us_ticker.c
- Committer:
- amithy
- Date:
- 2017-11-09
- Revision:
- 178:c26431f84b0d
- Parent:
- 149:156823d33999
- Child:
- 174:b96e65c34a4d
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 "mbed_error.h" #include "us_ticker_api.h" #include "PeripheralNames.h" #include "tmr_regs.h" #include "clkman_regs.h" #define US_TIMER MXC_TMR0 #define US_TIMER_IRQn TMR0_0_IRQn /** * Defines timer modes for 16 and 32-bit timers */ typedef enum { /** 32-bit or 16-bit timer one-shot mode */ MXC_E_TMR_MODE_ONE_SHOT = 0, /** 32-bit or 16-bit timer one-shot mode */ MXC_E_TMR_MODE_CONTINUOUS, /** 32-bit timer counter mode */ MXC_E_TMR_MODE_COUNTER, /** 32-bit timer pulse width modulation mode */ MXC_E_TMR_MODE_PWM, /** 32-bit timer capture mode */ MXC_E_TMR_MODE_CAPTURE, /** 32-bit timer compare mode */ MXC_E_TMR_MODE_COMPARE, /** 32-bit timer gated mode */ MXC_E_TMR_MODE_GATED, /** 32-bit timer measure mode */ MXC_E_TMR_MODE_MEASURE } mxc_tmr_mode_t; 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; /* Ensure that the TIMER0 clock is enabled */ if (!(MXC_CLKMAN->clk_gate_ctrl1 & MXC_F_CLKMAN_CLK_GATE_CTRL1_TIMER0_CLK_GATER)) { MXC_CLKMAN->clk_gate_ctrl1 |= (2 << MXC_F_CLKMAN_CLK_GATE_CTRL1_TIMER0_CLK_GATER_POS); } 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; uint32_t 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)); // Account for an unserviced interrupt 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); } }