mirror of https://github.com/ARMmbed/mbed-os.git
237 lines
9.0 KiB
C
237 lines
9.0 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2015-2016 Nuvoton
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "us_ticker_api.h"
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#include "sleep_api.h"
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#include "mbed_assert.h"
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#include "nu_modutil.h"
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#include "nu_miscutil.h"
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/* Micro seconds per second */
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#define NU_US_PER_SEC 1000000
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/* Timer clock per us_ticker tick */
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#define NU_TMRCLK_PER_TICK 1
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/* Timer clock per second */
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#define NU_TMRCLK_PER_SEC (1000 * 1000)
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/* Timer max counter bit size */
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#define NU_TMR_MAXCNT_BITSIZE 24
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/* Timer max counter */
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#define NU_TMR_MAXCNT ((1 << NU_TMR_MAXCNT_BITSIZE) - 1)
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static void tmr0_vec(void);
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static void tmr1_vec(void);
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/* Configure alarm exactly after scheduled clocks */
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static void arm_alarm(uint32_t cd_clk);
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static int ticker_inited = 0;
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static uint32_t ticker_last_read_clk = 0;
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/* NOTE: TIMER_0 for normal counting and TIMER_1 for scheduled alarm. */
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static const struct nu_modinit_s timer0hires_modinit = {TIMER_0, TMR0_MODULE, CLK_CLKSEL1_TMR0SEL_PCLK, 0, TMR0_RST, TMR0_IRQn, (void *) tmr0_vec};
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static const struct nu_modinit_s timer1hires_modinit = {TIMER_1, TMR1_MODULE, CLK_CLKSEL1_TMR1SEL_PCLK, 0, TMR1_RST, TMR1_IRQn, (void *) tmr1_vec};
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#define TMR_CMP_MIN 2
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#define TMR_CMP_MAX 0xFFFFFFu
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void us_ticker_init(void)
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{
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if (ticker_inited) {
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return;
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}
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ticker_inited = 1;
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ticker_last_read_clk = 0;
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// Reset IP
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SYS_ResetModule(timer0hires_modinit.rsetidx);
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SYS_ResetModule(timer1hires_modinit.rsetidx);
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// Select IP clock source
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CLK_SetModuleClock(timer0hires_modinit.clkidx, timer0hires_modinit.clksrc, timer0hires_modinit.clkdiv);
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CLK_SetModuleClock(timer1hires_modinit.clkidx, timer1hires_modinit.clksrc, timer1hires_modinit.clkdiv);
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// Enable IP clock
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CLK_EnableModuleClock(timer0hires_modinit.clkidx);
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CLK_EnableModuleClock(timer1hires_modinit.clkidx);
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// Timer for normal counter
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uint32_t clk_timer0 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
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uint32_t prescale_timer0 = clk_timer0 / NU_TMRCLK_PER_SEC - 1;
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MBED_ASSERT((prescale_timer0 != (uint32_t) -1) && prescale_timer0 <= 127);
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MBED_ASSERT((clk_timer0 % NU_TMRCLK_PER_SEC) == 0);
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uint32_t cmp_timer0 = TMR_CMP_MAX;
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MBED_ASSERT(cmp_timer0 >= TMR_CMP_MIN && cmp_timer0 <= TMR_CMP_MAX);
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((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname))->CTL = TIMER_PERIODIC_MODE | prescale_timer0 | TIMER_CTL_CNTDATEN_Msk;
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((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname))->CMP = cmp_timer0;
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NVIC_SetVector(timer0hires_modinit.irq_n, (uint32_t) timer0hires_modinit.var);
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NVIC_SetVector(timer1hires_modinit.irq_n, (uint32_t) timer1hires_modinit.var);
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NVIC_EnableIRQ(timer0hires_modinit.irq_n);
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NVIC_EnableIRQ(timer1hires_modinit.irq_n);
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TIMER_EnableInt((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
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TIMER_Start((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
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}
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uint32_t us_ticker_read()
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{
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if (! ticker_inited) {
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us_ticker_init();
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}
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TIMER_T * timer0_base = (TIMER_T *) NU_MODBASE(timer0hires_modinit.modname);
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ticker_last_read_clk = TIMER_GetCounter(timer0_base);
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return (ticker_last_read_clk / NU_TMRCLK_PER_TICK);
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}
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void us_ticker_set_interrupt(timestamp_t timestamp)
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{
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TIMER_Stop((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
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/* We need to get alarm interval from alarm timestamp `timestamp` to configure H/W timer.
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*
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* Because both `timestamp` and xx_ticker_read() would wrap around, we have difficulties in distinguishing
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* long future event and past event. To distinguish them, we need `tick_last_read` against which
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* `timestamp` is calculated out. In timeline, we would always have below after fixing wrap-around:
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* (1) tick_last_read <= present_clk
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* (2) tick_last_read <= alarm_ts_clk
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*
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*
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* 1. Future event case:
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*
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* tick_last_read present_clk alarm_ts_clk
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* | | |
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* --------------------------------------------------------
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* |-alarm_intvl1_clk-|
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* |-------------------alarm_intvl2_clk-------------------|
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*
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* 2. Past event case:
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*
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* tick_last_read alarm_ts_clk present_clk
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* | | |
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* --------------------------------------------------------
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* |-------------------alarm_intvl1_clk-------------------|
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* |-alarm_intvl2_clk-|
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*
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* Unfortunately, `tick_last_read` is not passed along the xx_ticker_set_interrupt() call. To solve it, we
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* assume that `tick_last_read` tick is exactly the one returned by the last xx_ticker_read() call before
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* xx_ticker_set_interrupt() is invoked. With this assumption, we can hold it via `xx_ticker_last_read_clk`
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* in xx_ticker_read().
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*/
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/* ticker_last_read_clk will update in us_ticker_read(). Keep it beforehand. */
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uint32_t last_read_clk = ticker_last_read_clk;
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uint32_t present_clk = us_ticker_read() * NU_TMRCLK_PER_TICK;
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uint32_t alarm_ts_clk = timestamp * NU_TMRCLK_PER_TICK;
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uint32_t alarm_intvl1_clk, alarm_intvl2_clk;
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/* alarm_intvl1_clk = present_clk - last_read_clk
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*
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* NOTE: Don't miss the `=` sign here. Otherwise, we would get the wrong result.
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*/
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if (present_clk >= last_read_clk) {
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alarm_intvl1_clk = present_clk - last_read_clk;
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} else {
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alarm_intvl1_clk = (uint32_t) (((uint64_t) NU_TMR_MAXCNT) + 1 + present_clk - last_read_clk);
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}
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/* alarm_intvl2_clk = alarm_ts_clk - last_read_clk
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*
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* NOTE: Don't miss the `=` sign here. Otherwise, we would get the wrong result.
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*/
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if (alarm_ts_clk >= last_read_clk) {
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alarm_intvl2_clk = alarm_ts_clk - last_read_clk;
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} else {
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alarm_intvl2_clk = (uint32_t) (((uint64_t) NU_TMR_MAXCNT) + 1 + alarm_ts_clk - last_read_clk);
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}
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/* Distinguish (long) future event and past event
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*
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* NOTE: No '=' sign here. Alarm should go off immediately in equal case.
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*/
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if (alarm_intvl2_clk > alarm_intvl1_clk) {
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/* Schedule for future event */
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arm_alarm(alarm_intvl2_clk - alarm_intvl1_clk);
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} else {
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/* Go off immediately for past event, including equal case */
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us_ticker_fire_interrupt();
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}
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}
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void us_ticker_disable_interrupt(void)
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{
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TIMER_DisableInt((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
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}
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void us_ticker_clear_interrupt(void)
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{
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TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
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}
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void us_ticker_fire_interrupt(void)
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{
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// NOTE: This event was in the past. Set the interrupt as pending, but don't process it here.
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// This prevents a recursive loop under heavy load which can lead to a stack overflow.
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NVIC_SetPendingIRQ(timer1hires_modinit.irq_n);
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}
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static void tmr0_vec(void)
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{
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TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
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}
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static void tmr1_vec(void)
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{
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TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
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// NOTE: us_ticker_set_interrupt() may get called in us_ticker_irq_handler();
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us_ticker_irq_handler();
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}
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static void arm_alarm(uint32_t cd_clk)
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{
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TIMER_T * timer1_base = (TIMER_T *) NU_MODBASE(timer1hires_modinit.modname);
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// Reset 8-bit PSC counter, 24-bit up counter value and CNTEN bit
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timer1_base->CTL |= TIMER_CTL_RSTCNT_Msk;
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// One-shot mode, Clock = 1 MHz
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uint32_t clk_timer1 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
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uint32_t prescale_timer1 = clk_timer1 / NU_TMRCLK_PER_SEC - 1;
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MBED_ASSERT((prescale_timer1 != (uint32_t) -1) && prescale_timer1 <= 127);
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MBED_ASSERT((clk_timer1 % NU_TMRCLK_PER_SEC) == 0);
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timer1_base->CTL &= ~(TIMER_CTL_OPMODE_Msk | TIMER_CTL_PSC_Msk | TIMER_CTL_CNTDATEN_Msk);
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timer1_base->CTL |= TIMER_ONESHOT_MODE | prescale_timer1 | TIMER_CTL_CNTDATEN_Msk;
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/* NOTE: Because H/W timer requests min compare value, our implementation would have alarm delay of
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* (TMR_CMP_MIN - interval_clk) clocks when interval_clk is between [1, TMR_CMP_MIN). */
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uint32_t cmp_timer1 = cd_clk;
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cmp_timer1 = NU_CLAMP(cmp_timer1, TMR_CMP_MIN, TMR_CMP_MAX);
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timer1_base->CMP = cmp_timer1;
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TIMER_EnableInt(timer1_base);
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TIMER_Start(timer1_base);
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}
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const ticker_info_t* us_ticker_get_info()
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{
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static const ticker_info_t info = {
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NU_TMRCLK_PER_SEC / NU_TMRCLK_PER_TICK,
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NU_TMR_MAXCNT_BITSIZE
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};
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return &info;
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}
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